Preparation, Inspection, and Optimization of Rotary Friction Welding Parameters for 2017aa Aluminum Alloy Specimens.

Preparation, Inspection, and Optimization of Rotary Friction Welding Parameters for 2017aa Aluminum Alloy Specimens. | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Preparation, Inspection, and Optimization of Rotary Friction Welding Parameters for 2017aa Aluminum Alloy Specimens. Tahar Nateche, Nabil Chakroune, Mouna Amara, Habib Boudaa, Ibrahim Ayad, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3989261/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract The qualification of the FSW process in aerospace requires the production of high-quality joints with long tool lifespan. This necessitates fine-tuning process parameters such as tool geometry (shoulder and pin dimensions, threading) and feed and rotation speeds. The experimental part involves characterizing the FSW weld joint through the study of mechanical properties and microstructural changes. The analyses and control observations performed on the obtained weld beads have, on one hand, enabled the correlation of joint quality with operational parameters. To achieve this, a local fabrication procedure aimed at producing defect-free joints was devised. Microstructural analysis revealed that the tool's rotation speed influences recrystallization conditions; the higher the rotation speed, the greater the welding energy and the more pronounced the softening of the material in the Heat Affected Zone (HAZ). FSW Microstructure Weld joint HAZ mechanical properties Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 I. INTRODUCTION AND OVERVIEW ON THE BACKGROUD In aeronautics, the weight factor is crucial. The welding process known as Friction Stir Welding (FSW), developed by Thomas Wayne at the British welding institute, The Welding Institute (TWI) [1], has a significant advantage in terms of reducing the weight of structures, which directly influences the fuel consumption of aircraft. This technique enables a solid-state assembly that facilitates the welding of alloys known for poor weldability using conventional fusion processes (TIG, GMAW, etc.), making its use highly valuable [2-6]. The base materials to be welded are never melted during the welding operation. The principle of this welding technology is based on the physical principle of friction welding in rotation. The major difference is the use of a rotating tool whose role is to stir and mix the material at the interface of the parts to be joined. The welding is done in the solid state (in a "pasty" state). More generally, FSW welding is particularly suitable for alloys with low melting points and high hot ductility, such as aluminum, magnesium, and even copper alloys [7-11]. The FSW welding process offers an alternative to the systematic riveting of various assemblies. Furthermore, it allows for a reduction in assembly time compared to automated riveting. An application has already emerged in the production of wing and fuselage parts. Indeed, the American company Eclipse Aviation Corporation has integrated the FSW process into the manufacturing of a jet, the Eclipse 500, thereby eliminating 60% of rivets [12]. Several parameters influence the movement of material and the microstructural and mechanical characteristics of the weld. The most influential parameters are the rotation and feed rates of the welding tool. Additionally, the tool itself, its geometry, the material it's made of, and its hardness also play a crucial role. Other parameters include the force applied to the tool, the angle of tool tilt, and the depth of the tool plunge into the material to be welded. The tool serves two main functions. Firstly, it generates friction against the workpiece, resulting in heat concentration that softens the material, and it facilitates the movement of material from the advancing side of the weld to the retreating side. The design of the tool significantly impacts the microstructure uniformity and, consequently, the mechanical properties of the joint. Threaded pins and concave shoulders are commonly used as they better knead the material and prevent overflow and burrs. Three distinct tool configurations are distinguished for Friction Stir Welding (FSW): the conventional tool, the retractable pin tool, and the double-shoulder tool, also known as the "Bobbin tool" or "Self tool». Rotation and feed rates are two critical parameters in Friction Stir Welding, as they determine the weld quality. The tool rotation rate, ω, is expressed in rotations per minute (rpm), while the tool feed rate, γ, is expressed in millimeters per minute (mm/min). In this process, unlike conventional continuous processes, the welding occurs "blindly," meaning that the shoulder and pin completely conceal the underlying phenomena of the weld. The lack of direct visual observation poses challenges in parameter determination and real-time monitoring of the ongoing welding. Consequently, the necessity for a monitoring and control system for real-time parameter management arises. Furthermore, at the end of the weld bead, the tool withdrawal leaves a hole that cannot be simply filled through FSW. For open linear welds, this requires the implementation of plugs that need to be removed at the beginning and end of the weld bead [13]. The mechanical and thermal phenomena in all fusion welding processes lead to a modification of the microstructure of the base material and its mechanical properties. This drawback arises from the metallurgical phenomena that occur during welding and which represent the location of stress concentration in the case of external stresses. The first metallurgical phenomenon is the modification of the material's precipitation state. The second is the recrystallization of the material. In contrast, the Friction Stir Welding (FSW) process allows obtaining less significant metallurgical modifications compared to other processes, caused by the various phase changes during welding. A cross-sectional cut of the welded joint reveals different zones in which the material is thermally affected (Heat Affected Zone HAZ) or thermomechanically affected (Thermo Mechanical Affected Zone TMAZ). Each zone depends on the attained temperature, metallurgical changes, and deformations undergone during the welding process. The exothermic and endothermic peaks present in this figure correspond to the precipitation reactions illustrated in the equilibrium phase diagram of stable and metastable phases within the Al-Cu system region, and they are evenly distributed across the spectrum. These precipitation phenomena are clearly revealed by the Differential Scanning Calorimetry (DSC) thermogram obtained from the base metal. The microstructure is similar to that observed in the base metal. It should be noted that the different precipitates identified in this study are the same as those reported in other research works for the Al-Cu system. In this section, studies of the FSW process carried out by the research group at the Algerian Research and Development Center (CRD / FA) were subjected to in-depth analysis: Mimouni et al. [14] conducted a comparative study between FSW and LAFSW (Laser Friction Stir Welding) using the FLUENT software. They concluded that the flow velocity around the pin increases when the number of stirring parts (agitation pieces) rises. Additionally, preheating before the tool pass plays a beneficial role in the welding quality. Chekroun et al. [15] performed an experimental study on the friction stir welding of the 2017AT451 aluminum alloy, varying the tool rotation speed from 950 to 1250 rpm. The results showed that the increase in tool rotation speed leads to significant growth of grains in the Heat-Affected Zone (ZAT) and enhances recrystallization of the Near-Zone (NZ) microstructure. In the same context, the experimental thermal cycles indicate that the temperature peak reached during the welding process is entirely sufficient to trigger precipitation phenomena for 2017AA. Mimouni et al. [16] studied the flow behavior around a tool used in the FSW process. The heat generated during FSW must be sufficiently ample to soften, mix, and blend the material. A reasonable agreement between the temperature values obtained from the model and those measured in the experiment is observed. Friction Stir Welding (FSW) is a solid-state welding process that was invented in 1991 by The Welding Institute (TWI), United Kingdom [17]. While dead weight processing is often used as a technique for welding aluminum alloys [18,19], it has also been employed for welding numerous other metals such as magnesium alloys [20,21], titanium alloys [22,23], and matrix composite metals [24,25]. Furthermore, similar or different materials of varying thicknesses can be welded using this method. This section summarizes the recent experimental and numerical research on the FSW process. Motivated with the above recent reported technologies in the field FSW of aluminum, we are addressing in this work the development of a local design of a FSE tool that are characterized by smooth operations and better control of the process parameters. II. EXPERIMENTAL STUDIES In this section, the various experimental and numerical methods are described in the present study. Firstly, the mechanical tests conducted and the procedures followed to determine, in particular, the mechanical behaviors under tensile, flexural, and fatigue loading conditions are presented. Secondly, the methodology adopted for the numerical simulation of this type of Friction Stir Welding (FSW) to determine the heat flow behavior is discussed. II.1 Materials studied During the course of this study, a base material was investigated: an alloy from the 2000 series (Aluminum-Copper). The alloy used for welding exhibits a structural hardening process known as "Age-hardening" (AU4G-1). In the context of this work, the alloy was examined in a metallurgical T6 condition, which corresponds to the as-received state of the sheet. Chemical analyses were conducted at the Materials Laboratory of the Air Force Research and Development Center "CRD-FA" - Dar El Beida. X-ray fluorescence spectrometry was employed using a mass spectrometer designed for light alloys, branded as "SPETRO." The chemical composition of the 2017AA alloy is indicated in Table 1. Table1. Chemical composition of the base metal (2017AA) determined by X-rays. Elements Si Fe Cu Mn Mg Zn Ti Cr Al % (Weight) 0.38 0.52 1.36 0.27 2.23 5.74 0.19 0.22 89.09 Energy Dispersive X-Ray Fluorescence (EDX) analysis enables the qualitative and quantitative elemental composition determination of a sample by measuring the energies of X-ray photons emitted from the region of the sample bombarded by an electron beam using a detector. Metallic elements emit X-rays at characteristic energies when subjected to high-energy X-ray irradiation. The X-ray spectrum emitted by the material is indicative of the sample's composition. By analyzing this spectrum, one can deduce the elemental composition, i.e., the mass concentrations of the elements. One of the samples took the form of 6 mm thick rolled sheets, while another sample comprised 10 mm thick rolled sheets that were used for creating welded joints through Friction Stir Welding (FSW). II.2 Preparation of the welding plates Plates measuring 100 mm in width and 250 mm in length were cut from a sheet of 2017AA aluminum of thicknesses 6 mm and 10 mm using an industrial saw. In order to eliminate the deformations caused by the cutting process, the plates underwent a second stage of machining on a milling machine, treating both sides. These steps ensured that the plates were free from distortions at the edges, thereby achieving uniform joints. II.3 welding tools All the tools are made of H11 steel (tool steel Z38CDV5.1), which has a higher melting temperature and hardness compared to aluminum. Table 2 displays the chemical composition of this steel. Table 2. Chemical composition of tool steel Z38CDV5.1. elements C Si V Cr Mn Fe Ni Cu Mo % weight 0.393 0.110 0.293 4.567 0.926 92.054 0.165 0.076 1.016 II.3.1 Realization of the FSW tool Tools were manufactured to perform the butt welding of plates. These tools have the same shoulder and pin geometry. The pin lengths are 5.80 mm and 9.80 mm, respectively, in order to weld plates of different thicknesses (6 mm and 10 mm). The characteristics of the welding tools are shown in Table 3, and Figure 1 displays the tools before and after heat treatment. The FSW welding tool undergoes heat treatment (heated up to 1010°C, held for 20 minutes, and then rapidly cooled in oil) [26]. The hardness before and after quenching is 30 and 54 HRc, respectively. Table 3. Characteristics and dimensions of FSW welding tools used to weld alloy 2017AA. Alloy 2017AA Seal type Shoulder Pawn Diameter (mm) Type Diameter (mm) Type Length (mm) Plates 6 mm Butt welding 25 Concave 6 With thread 5.80 Plates 10 mm 8 9.80 II.3.2 Welding machines Currently, the main machines used for Friction Stir Welding (FSW) are modified milling machines, machines designed specifically for FSW, and robots. In this study, welding was performed on a conventional milling machine with a maximum rotation speed of 2000 RPM and a feed rate of 900 mm/min. This machine is located in the workshops of the Aeronautical Equipment Renovation and Maintenance Company (ERMA-Aéro). Modifications were necessary to adapt the table for setting up a test bed to carry out the welds. II.3.3 Implementation phase of the welding technique The welding was carried out at the ERMA-Aero level. Before welding, the sheets need to be cut to the same dimensions. The first one is positioned so that the edge to be welded is parallel to the advance of the pin during welding. Then, the two sheets are clamped. Figure 3 shows a 5 cm thick steel plate placed beneath the material to thermally isolate it from the support and verify flatness. Subsequently, the welding parameters, rotation speed, and welding speed are programmed, and the head's inclination is adjusted. The main steps used during welding are as follows:(i) Position the tool above the plates at the beginning of the joint and tilt the tool by 2 degrees; therefore, it is necessary to clamp the pieces laterally and vertically to prevent them from lifting or separating during welding. Figure 4.a presents the possible clamping configuration used to prevent any movement of the pieces during the welding operation.(ii) Initiate and adjust the rotation of the machine's head, as shown in Figure 4.b (three rotation speeds for each thickness);(iii) Submerge the tool and wait for 2 seconds [27]. This delay is necessary to achieve thermal balance (Figure 4.c);(iv) Start moving the tool at a feed rate of 0.6 mm/s (Figure 4a.c), and(v) Raise the tool at the end of the joint and stop the machine. The length of the plates was oriented in the rolling direction so that the welded joint is also in the rolling direction (Figure 4.d). The plates were welded with the parameters mentioned in Table 4. For both thicknesses, the tool feed rate and the tilt angle were fixed, and the rotation speed was varied to study its effect on FSW welding. The choice of rotation speeds was made based on a multitude of preliminary tests. There are two types of welds: cold welds, where the rotation speed/feed rate ratio is less than 1 rev/mm, and hot welds, where this ratio is greater than 1 tr/mm [28]. In our case, the ratio ranges from 26 to 40 tr/mm, thus referring to a hot weld. Table 4. Welding parameters and sizes of welded plates. Alloy 2017A Length x length Tests Rotation speed (rpm) Feed rate (mm/min) Tilt angle (°) Report N/Va (tr/mm) Plates 6 mm 250 x 100 Test 950 36 2 26 test 1050 29 test 1250 35 Plates 10 mm 250 x 100 test 1050 29 test 1250 35 test 1450 40 II.3 Means of quality control of welds The welds were inspected using three non-destructive methods: visual inspection, radiography, and ultrasonic testing. The examination focused on the weld beads and the imprint (crevice) left by the tool at the end of welding. These examinations serve to ascertain the potential presence of surface or internal defects. II.3.1 Rayons X analysis The generator used for radiographic inspection employs an X-ray tube with a copper (Cu) cathode, manufactured by SEIFERT, with a maximum power of 900 kW (Figure 5), using settings specific to aluminum. The 6 mm thick FSW (Friction Stir Welding) joint inspected through radiography is the one achieved at a rotational speed of 1250 rpm. A 200 mm longitudinal weld is located at the center of the two plates. The joint undergoes radiographic testing to detect potential defects. These defects are identified through observation of the digitized radiographic image. The other two configurations (welded joint at 950 rpm and welded joint at 1050 rpm) are not subjected to radiographic examination due to a lack of radiographic films at the CRD-FA level. The same applies to the joint made on 10 mm thick plates; only the joint welded at a rotational speed of 1250 rpm is inspected using radiography. The other two configurations are not inspected via radiography (welded joint at 1050 rpm and welded joint at 1450 rpm). II.3.2 Ultrasonic inspection. Ultrasonic inspection of FSW welds was conducted at the Aeronautical Structures Fatigue and Reliability Laboratory (CRD-FA). Two types of testing methods were employed. The first involved immersion testing using a tank designed for laboratory characterization. The second method utilized contact testing. II.3.3 Exam by echography-Ultrasonore(E/R). Two ultrasonic devices of the brand KRAUTKRAMER-Branson USD 15 (Figure 5.b.1) and USD-100B type (Figure 5.b.2) are used for defect detection in emission/reception mode. For the surface wave survey, two probes were used: one as the transmitter (Harisonic ABM 0506 90° ST 5.0 MHz) and the other as the receiver (Panametrics NDT 5 MHz-0.5’). They are intended for transmission surveys. For internal defect detection, two angle probes were employed, both used in contact mode: the MWB-70 probe (f = 4 MHz) and the MWB-45 probe (f = 4 MHz). Additionally, two transducers were used: one for longitudinal wave transmission, a Panametrics A120R (62654) with a frequency of 7.5/0.5’, and the other for shear wave transmission, a Panametrics V155 (174913) with a frequency of 5.0/0.5’. Following the calibration of the ultrasonic equipment, the applied ultrasonic scanning is carried out in a manner that covers the entire surface potentially containing any defects. To achieve this, a "ZIG-ZAG" scanning approach was chosen (Figure 6). The scanning is performed on both sides of the weld in order to locate the maximum of defects. The area of the scanning zone is traversed using two types of movements. (i) A Zig-Zag motion parallel to the axis of the weld with a step that does not exceed the width of the probe, and (ii) A pivoting motion: While approaching and moving away from the welded joint, the probe must oscillate at an angle of 10 to 15° on each side of the normal to the axis of the joint [30-31]. With this type of movement, it is possible to distinguish between volumetric defects and linear defects. II.4. Observations and analyzes This paragraph aims to present the various experimental techniques that were applied during this study in order to characterize the microstructure of welded joints at different scales. The description of the methods will be carried out considering observation scales that become increasingly finer. II.4.1 Optical Microscopy The friction stir welding process results in the formation of different zones, with sizes on the order of a few millimeters. Optical microscopy is employed to conduct initial examinations of the various microstructures in the obtained joints. These observations were carried out using a “Leica DM 2500 M” optical microscope connected to a microcomputer equipped with “Leica Application Suite LAS” image acquisition software for image transfer and processing (Figure 7.a). To characterize the microstructure of the welded joints and identify the different zones, a Keller’s reagent etching was performed. Prior to etching, the sample must be mechanically polished using 240-grit paper to achieve a mirror finish with 3μm diamond paste. The metallographic etching involves immersing the sample in Keller’s reagent (2.5 ml nitric acid HNO 3 , 1 ml hydrofluoric acid HF, 1.5 ml hydrochloric acid HCl, and 95 ml distilled water) for 10 seconds, followed by rinsing with distilled water. II.4.2 Measurement of grain size To measure the grain size, we employed the three-circle method. Images captured by the optical microscope are digitized and subsequently analyzed using an image acquisition software, "Leica Application Suite LAS." Figure 7b illustrates an example of the analysis of these images. II.4.3 Scanning Electron Microscopy (SEM) Scanning electron microscopy observations were performed to complement the optical microscopy observations and to analyze fracture features after tensile and fatigue tests. These observations were conducted to evaluate the mechanical behavior of the tested materials. Additionally, due to the attainable magnifications, scanning electron microscopy allowed for a more precise examination of the microstructure of welded joints during the various tests conducted in this study. Sample polishing was carried out when a flat surface was required. In the case of fracture feature analysis, samples were observed without specific preparation. Micrographic examinations of the sample surfaces were conducted using a QUANTA 600FEI scanning electron microscope available at the Laboratory of Materials Engineering (LGM) at the Polytechnic Military School of Bordj El Bahri (EMP) (Figure 8). The microscope was equipped with an infrared camera capable of producing digital images. II.4.4 X-ray Diffraction (XRD) X-ray diffraction was utilized to obtain qualitative information about the different phases under investigation. This method provides insights into the crystalline structure and enables the evaluation of lattice parameters or the relative proportions of each phase. The complete set of diffraction spectra was obtained using an "X'PERT-PRO" diffractometer (Figure 8b). Monochromatic X-ray radiation was generated using a copper anticathode, and the Kα1 (1.5406 Å) and Kα2 (1.54443 Å) lines were isolated through absorption discontinuity with the use of a germanium filter. The tube operated with the following power settings: V = 45 kV, I = 40 mA. Table 5 summarizes the measured mechanical characteristics of the 2017AA alloy. Table 5. Mechanical characteristics of the 2017AA alloy. 2017AA ρ (kg/m3) Ν E (GPa) λ (GPa) μ (GPa) 2741.94 0.34 72.88 58.78 27.15 III. RESULTS AND DISCUSSION III.1 Welding of 6mm and 10mm Thick Sheets Three welding operations were performed on the 6mm thick plates, with rotation speeds of 950, 1050, and 1250 RPM, and a constant feed rate of 0.6 mm/s. The inclination angle is 2°, as shown in Figure 9. Symbols (a, face) represent the side of the weld bead, and (a, side) represents the opposite side. In Figure (a), the welding was conducted at a rotation speed of N = 950 RPM, and an acceptable joint quality was achieved with striations on the joint surface Figure 9.b illustrates the weld bead obtained at a rotational speed of 1050 rpm. A relatively smooth and defect-free bead is observed, with a width equal to the diameter of the shoulder. This bead exhibits good visual quality. Two experiments were conducted using a rotational speed of 1250 rpm on 6 mm plates. Figure 9.c depicts a smooth bead surface with a well-distributed pattern of ridges resulting from the increased rotational speed, which generates a significant amount of heat, facilitating material mixing. As is the case for the 6 mm thick plates, three welding operations were performed on the 10 mm thick plates, with rotation speeds of 1050, 1250, and 1450 rpm and a constant feed rate of 0.6 mm/s. The tilt angle is 2° (Figure 10). Referring to Figure 10.a, for the welding of the 10 mm thick plates with a rotation speed of 1050 rpm, a lack of material mixing is observed due to a low rotation speed in relation to the plate thickness. The joint was formed, but with tunnel-type defects on the surface. This defect occurs when the operating conditions are cold, leading to insufficient material mixing. Two tests were conducted with a rotation speed of 1250 rpm on the 10 mm plates. It can be seen that for this configuration, the quality of the joint obtained is better compared to that obtained with a rotation speed of 1050 rpm (Figure 10.b). Figure 10.c shows the weld bead obtained with a rotation speed of 1450 rpm on the 10 mm plates, revealing an acceptable bead width equal to the diameter of the shoulder. Note that in some cases, the hole left by the tool during the upward phase is filled by the breakage of the tool pin at the end of the welding operation, as shown in Figure 10.c. Therefore, the operation concluded with a burnt tool and without a pin. The weld beads obtained after welding on the used aluminum alloy 2017AA demonstrated that the rotation speed and thickness influence the quality of the weld. It is observed that the welds on the 6 mm thick plates are better compared to those on the 10 mm thick plates, and as the rotation speed increases, the weld quality improves. Once the welds are completed, it is necessary to evaluate the different joints obtained. III.2 Analysis of Defect Generation Based on Operating Parameters The encountered defects align with those described in Chapter I of the literature review for other aluminum alloy compositions. The identified defects for each welding configuration are presented below. III.2.1 Defects identified by visual inspection For all welds, the width of the imprint left by the tool during the penetration phase is the same as that of the weld bead. If the tool retracts slightly, the mixing beneath the pin becomes inadequate, leading to the occurrence of the partial penetration defect (Figure 11.a). During welding, the tool penetrates into the material, resulting in excessive tool penetration. This leads to the formation of excessive burrs (Figure 11.b), consequently causing a reduction in the weld section. This burr corresponds to the surplus material displaced by the tool as it penetrates. This type of defect is referred to as "Ribbon flash". Surface defects such as insufficient marking of the shoulder and scratches, left on the surface by the passage of the shoulder over the weld bead, are shown in Figure 11.c. For 10 mm thick plates, with a low rotational speed of 1050 rpm, a groove-type defect is observed on the joint surface, originating from insufficient heat input provided by the tool (Figure 11.d). III.2.2. identified through radiographic examination The 6 mm thick plates do not contain internal defects. Figure 12.a shows an example of a radiographic examination of the weld joint of the plates at 1250 rpm. Only the streaks left by the passage of the tool are observed in this radiographic image. For a thickness of 10mm, this configuration exhibits an internal tunnel defect. This corresponds to a lack of material consolidation at the shoulder passage. The radiograph of a bead (Figure 12.b) shows this defect. It can appear at the beginning or in the middle of the weld after a few millimeters of welding. In our study, its origin is attributed to a mixing flaw. The weld bead presents a good surface condition, but internally, upon radiographic examination, an internal tunnel defect is observed along the joint, visible to the naked eye in the digitized image. III.2.3 Defects identified through ultrasonic examination To detect potential defects, it is necessary to examine the weld over its entire cross-section and along its entire length. III.2.3.1 Surface defect detection. All welds are examined using ultrasonic testing to detect surface defects. Only two configurations contained defects: lack of penetration defects on 10 mm thick plates welded at a rotation speed of 1450 rpm, and lack of marking defects on the shoulder, also in 10 mm thick plates welded at 1250 rpm. III.2.3.2 Internal defect scanning using straight E/R probe. Among the techniques employed for detecting internal defects in weld joints, a straight probe with an emitter-receiver relay for longitudinal wave transmission at 10MHz/25 was used. Figure 13.a illustrates an example of examination on 10 mm thick welded plates. In this configuration, the opposite side was examined due to its good surface condition. For 10 mm thick plates welded at 1250 RPM, the presence of a defect is observed (Figure 13.a). The depth of this defect is 5.59 mm relative to the opposite surface of the joint. Figure 13.b displays an oscillogram received by the probe in a non-welded area on 6 mm thick plates. According to Figure 14, there is no change in the oscillogram provided by the ultrasonic E/R probe compared to the reference oscillogram. This demonstrates the absence of internal defects in the 6 mm thick sample joint. III.2.3.3. Internal defect assessment through oblique incidence contact. The previous result from section V.3.3.2 is corroborated by an oblique incidence examination using a 70° angle probe and a Krautkramer Branson USD 15 ultrasonic device, after its adjustment. Following a Zig-Zag type scanning, the defect is localized along the joint. Its depth is directly displayed on the device (Figure 15), measuring approximately 5.18 mm relative to the joint surface. Figure 16 illustrates an example of defect localization within the 10 mm thick joint welded at a speed of 1250 RPM. The presence of two defect echoes is noted due to the complex geometry of the internal defect. Table 6 summarizes the synthesis of non-destructive examinations conducted on the weld joints for the two thicknesses used. Table 6. Types of defects present at the FSW joint level. Plates Rotational speed N (rpm)) Type of defect Surface defect Défaut interne 6mm 950 No defects No defects 1050 Lack of shoulder marking No defects 1250 No defects No defects 10mm 1050 Uncontrolled configuration 1250 Lack of shoulder marking Tunnel interne 1450 Lack of penetration No defects Figure 17 illustrates the attenuation of longitudinal waves during the inspections of the sound joint and the base metal. Contact inspections on the 6 mm thick piece conducted under the same setting parameters show an attenuation of approximately 27%. III.3 Analysis of Micrography In this section, the different types of microstructures composing several welded joints are also presented. Indeed, depending on the conditions obtained during welding, such as temperature and deformation rate, the weld can be decomposed into several zones, each having its own characteristics. These observations provide insights into the mechanisms occurring during welding and allow for the comparison of results from different microstructures. The metallography of the majority of welds was conducted to study the microstructure of the four constituent zones of the joint in relation to the tool's rotation speed. The micrographs of the joint reveal the presence of four distinct zones (weld core denoted as NS, heat-affected zone denoted as ZAT, thermo-mechanically affected zone denoted as ZATM, and the base metal denoted as MB). These zones are the result of the thermal and thermomechanical history of the joint. Presented below is a study aimed at determining the variation of welding zones (ZAT, ZATM, Core) based on the tool's rotation speeds for 6 mm thick 2017AA aluminum plates welded end-to-end. The provided photos below illustrate the different microstructures of the welded samples. In these images, the advancing side is identified as "AS," while the retreating side is labeled "RS." Welds produced by FSW exhibit a highly heterogeneous macrostructure along the weld. Four zones with different microstructures are distinguished in the FSW-welded joint: base metal, weld core, thermo-mechanically affected zones ZATM (AS and RS), and heat-affected zones ZAT (AS and RS). III.3.1 Welded Plates at a Rotation Speed of 950 rpm The main difference between the zones is the grain size in each zone. Figure 18 illustrates optical microscope observations of each zone in the FSW-welded joint using 2017AA aluminum alloy at a rotation speed of 950 rpm. The ZAT is the zone where the temperature is sufficiently high to cause overaging of the base metal. It is situated between the base metal and ZATM. In this zone, the grain morphology is nearly the same as that of the base metal (Figure 18.b, e). The ZATM is the zone located between the core and ZAT. In this zone, grain deformation occurs, but the temperature is below critical values to activate dynamic recrystallization mechanisms. Figure 18.c, d show that the transition between the core and ZATM is much sharper on the AS side than on the RS side. This is caused by the deformation gradient. It also shows grains elongated in the direction of metal flow during welding. The joint's core is the zone where temperature and plastic deformation are sufficiently high to induce grain recrystallization. In this zone, the grain size is approximately 5 microns, significantly smaller than the grain size of the base metal (Figure 18.h). The base metal zone is where the temperature remains below the aging temperature. The metal undergoes no transformation. The micrograph shown in Figure 18.h displays elongated grains due to cold sheet rolling. The figure also indicates the presence of inclusions. III.3.2. Welds at a Rotational Speed of 1050 RPM Figure 19a illustrates the weld core obtained at a speed of 1050 rpm. A fine microstructure is observed, consisting of grains ranging from 8 to 12 μm. The thermal and mechanical loads experienced during the welding process have led to the complete recrystallization of this region. According to Figure 19d, the thermal and mechanical loads applied result in significant plastic deformation and grain orientation in the direction of the tool's rotation. The grain size in this region ranges from 50 to 80 μm. It is notable that the grain elongation in the Heat-Affected Zone on the Retreating Side (Figure 19f) is less pronounced than on the Advancing Side (Figure 19e).In the Heat-Affected Zone (HAZ) (Figures 19b, c), both the granular structure and grain size remain consistent with the base material. Thus, the grain size in this zone is similar to that of the base material, ranging from approximately 100 to 130 μm. III.3.3 Welds at a Rotation Speed of 1250 rpm The microscopic analysis of the weld joint at 1250 rpm (Figure 20) allows for a clear distinction of the HAZ, HAZM, and Core zones. The effect of the tool's movement is observed in the kneaded portion due to the change in orientation of deformation planes within the Core and HAZM. The HAZM lies on either side of the Core and undergoes a complex thermal history and plastic deformation induced by the movement of the tool's pin and its threading. This threading can initiate recrystallization and precipitation phenomena. In the Core, grains become significantly smaller due to intense thermomechanical deformation and dynamic recrystallization effects. Furthermore, the grain size in the Core is always finer than that in the HAZM due to partial recrystallization in the latter, while it is complete in the Core. In the transition zone between the Core and the AS HAZM (Figure 20.d), the boundary between these two zones is clearly marked by the grain size variation—Core grains are finer than those in the HAZM. Both the HAZ and HAZM are wider in cases of higher rotation speeds. However, the width of the Core remains constant for all welds as it corresponds to the geometry of the tool's pin. In conclusion, during the friction-kneading process, the increase in temperature and material deformation caused by the rotation and advancement of the pin result in modifications to the initial microstructure of the plate (the base metal) within the joint. III.4. X-ray Diffraction X-ray diffraction (XRD) is the most suitable method for revealing the phases present in materials; it is highly sensitive to any disruption of the periodicity of the crystalline lattice. The XRD spectra obtained from two samples, welded and non-welded (base metal), as shown in Figure 21(a) and (b), appear nearly identical but with a greater intensity than in the base metal. Table 7. Position of the XRD peaks obtained for a welded sample. α(Al) 2 Theta (°) 38.22 44.48 64.92 78.12 112.11 116.51 (hkl) 111 200 220 311 331 420 d (hkl) 2.35 2.03 1.43 1.22 0.92 0.90 η (Al-Zn-Mg-Cu) 2 Theta (°) 82.39 99.16 137.50 - - - (hkl) 222 400 422 - - - d (hkl) 1.17 1.01 0.82 - - - Table 8. Position of the XRD peaks obtained for an unwelded sample (base metal). α(Al) 2 Theta (°) 38.49 44.71 65.18 78.34 116.74 (hkl) 111 200 220 311 420 d (hkl) 2.33 2.02 1.43 1.22 0.90 η (Al-Zn-Mg-Cu) 2 Theta (°) 82.50 99.24 112.25 137.50 - (hkl) 222 400 331 422 - d (hkl) 1.16 1.01 0.92 0.82 - We observe that there is a difference in peak intensity, which is due to the residual stresses existing at the welded joints and the degree of crystallinity. For the two studied samples, the identification of the lines that appear corresponds well to the α phase (Al) of aluminum and the intermetallic phase η (Al-Zn-Mg-Cu). It can be noted that the peaks of the α phase (Al) along the (111) and (200) planes are the most intense. Tables V.2 and V.3 compile the XRD characteristics for the two studied samples. IV. DISCUSSION OF RESULTS, CONCLUSION, AND RECOMMENDATIONS The friction stir welding (FSW) process proves to be advantageous for the welding of aluminum alloys, and it holds a highly promising future across various application domains. Most studies aimed at improving the welding process are still conducted experimentally, necessitating further refinement of welding tools and utilization parameters. Several focal points characterizing the friction stir welding process have been emphasized and studied. Subsequently, a two-fold approach has been pursued: firstly, a study of microstructural characterization, aiming to comprehend the effect of welding parameters on the mechanical properties of the welded joint. In the experimental segment, the FSW joint was characterized through the investigation of mechanical properties and microstructural changes. Analyses performed on the obtained weld beads enabled the correlation of joint quality with operating parameters. To achieve this, a fabrication procedure was developed to produce defect-free joints. It was demonstrated that welds executed on 6 mm thick plates outperform those obtained on 10 mm plates. These results are corroborated by non-destructive inspection and evaluation methods. Through microhardness testing and macroscopic observations, microstructures within different zones of the FSW bead were correlated with hardness evolution. The hardness curve profile in the heat-affected zone (HAZ) was also explained. In fact, the temperature gradient experienced by this zone leads to the observed hardness gradient. In the center of the bead, hardness increases, eventually reaching the base metal hardness. The microhardness within the heat-affected zone for the studied alloy is lower compared to other zones (nugget zone, thermo-mechanically affected zone, and the base metal). The joint obtained using the following parameters: thickness = 6mm, N = 1250 rpm, Va = 0.6 mm/min exhibited optimized mechanical characteristics. The fracture surfaces of the tensile specimens were analyzed using a Scanning Electron Microscope. Based on various observations, a mixed fracture mode was identified: a ductile rupture zone, where SEM observations revealed the presence of dimples, and another abrupt rupture zone. The presence of cavities was noted in precipitate-rich regions across the ductile rupture zone for different combinations of welding parameters. Microstructure analysis demonstrated that the tool's rotation speed influences recrystallization conditions. Higher rotation speeds lead to greater welding energy and significant softening of the material in the HAZ. Metallographic characterization techniques highlighted the extent, grain size, and microstructural morphology of different zones within the weld bead (nugget zone, HAZ, thermo-mechanically affected zone, and base metal). In light of the findings of this study, future research avenues are conceivable. From an experimental standpoint, it would be interesting to investigate the effects of other FSW process parameters, such as traverse speed and tilt angle, on the mechanical properties of welded joints, and establish a correlation between microscopic phenomena and the macroscopic response of the welded structure. Additionally, post-welding heat treatments are necessary to study the influence of these treatments on the mechanical and microstructural properties of FSW-welded joints. Furthermore, expanding the scope of studied weldability, such as employing alternative tool geometries for varying thicknesses and welding the 2017AA alloy with a dissimilar natured alloy, is proposed. Declarations Conflicts of Interest The authors declare no conflict of interest. Contributions T.N, N.C., M.A., H.B., I.A., S.M., and M.H.M. conceived and designed the experiments; R.K.S., S.L., and A.G. carried out the experiments; M.H.M., R.K.S., and G.P. analyzed the experimental data and wrote the manuscript. All authors have read and agreed to the published version of the manuscript. References Thomas WM Temple-Smith P (TWI, rights transferred to Lead Sheet Association): 'Friction welding sheet material'. UK Patent Application GB 2 319 977 A Nasution AK, Gustami H, Suprastio S, Fadillah MA, Octavia J, Saidin S (2022) Potential use of Friction Welding for Fabricating Semi-Biodegradable Bone Screws. Int J Automot Mech Eng 19:9660–9667 Rhodes CG, Mahoney MW, Bingel WH (1997) Effects of friction stir welding on microstructure of 7075 aluminum. ScriptaMaterialia 36(1):69–75 Hagstrom J, Sandstrom R (1998) Static and dynamic properties of joints in thin-walled aluminum extrusions, welded with different methods. Proceedings of 6th International Conference on Aluminum Alloys, Toyohashi, Japan, pp.1447–1452 Hashimoto T, Nishikawa N, Tazaki S, Enomoto M (1998) Mechanical properties of joints for aluminum alloys with friction stir welding process. 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Engineering Manufacturing Sun Y, Voyiadjis GZ, Hu W, Shen F, Meng Q (2017) Fatigue and fretting fatigue life prediction of double-lap bolted joints using continuum damage mechanics-based approach. Int J Damage Mech 6:162–188 Shanjeevi C, Arputhabalan J, Pavithran E, Raju B (2019) Prediction of Optimized Friction Welding Parameter for Joining of Dissimilar Material using Friction Welding. Mater. Today Proc. 16, 838–842.Proc. 2022, 57, 687–692 Paventhan R, Lakshminarayanan PR, Balasubramanian V (2012) Optimization of Friction Welding Process Parameters for Joining Carbon Steel and Stainless Steel. J. Iron Steel Res. Int. 19, 66–71. Compd. 2017, 695, 3267–3277 Mimouni O, Badji R, Kouadri-David [22] A, Gassaa R, Chekroun N, Hadji M (2019) Microstructure and Mechanical Behavior of Friction-Stir-Welded 2017A-T451 Aluminum Alloy. Trans Indian Inst Met. pp. 1–16 Chekroun N, Mimouni O, Badji R, Gassaa R, Hadji M (2016) January. 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Sci Technol Weldingand Join 9:345–351 Cerri E, Leo P, Wang X, Embury J (2011) Mechanical properties and microstructural Evolution of friction-stir-welded thin sheet aluminum alloys. Metall Mater Trans 42:1283–1295 Cerri E, Leo P, Wang X, Embury J (2011) Mechanical properties and microstructural Evolution of friction-stir-welded thin sheet aluminum alloys. Metall Mater Trans 42:1283–1295 Silva AC, Braga DF, de Figueiredo M, Moreira P (2015) Ultimate tensile strength optimization of different FSW aluminium alloy joints. Int J Adv Manuf Technol 79:805–814 Sonne MR, Tutum CC, Hattel JH, Simar A, De Meester B (2013) The effect of hardening laws and thermal softening on modeling residual stresses in FSW of aluminum alloy 2024-T3. J Mater Process Technol 213:477–486 Cao X, Jahazi M (2011) Effect of tool rotational speed and probe length on lap joint quality of a friction stir welded magnesium alloy. Mater Des 32:1–11 Nandan, Nandan R, DebRoy T, Bhadeshia H et al (2008) Recent advances in friction-stir welding-process, weldment structure and properties. Prog. Mater. Sci. 2008, 53, 980–1023 Prasanna Nagasai B, Malarvizhi S, Balasubramanian V (2022) Mechanical properties and microstructural characteristics of AA5356 aluminum alloy cylindrical components made by wire arc additive manufacturing process. Mater Per Cha 11(1):1–26 [30] S, Raja A, Sachin Adithyaa V, Sai Yaswanth R, Saranya U, Sabarivasan (2020) Establishing an empirical relationship to predict strength of dissimilar friction welded steel joints. Paideuma J 13(7):68–82 [31] G, Vairamani T, Senthil kumar S, Malarvizhi V, Balasubramanian (2013) Predicting tensile strength and interface hardness of friction welded dissimilar joints of austenitic stainless steel and aluminium alloy by empirical relationships. 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J Mech Beha Mat 30:188–198 Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major Revisions Needed 01 Jun, 2024 Reviewers agreed at journal 05 Apr, 2024 Reviewers invited by journal 08 Mar, 2024 Editor assigned by journal 07 Mar, 2024 First submitted to journal 05 Mar, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3989261","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":277480203,"identity":"673a07d6-ed28-4920-92b9-d8f75ec5b62d","order_by":0,"name":"Tahar Nateche","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Tahar","middleName":"","lastName":"Nateche","suffix":""},{"id":277480204,"identity":"93f57df8-dc8e-4929-9abc-51538cd8ba33","order_by":1,"name":"Nabil Chakroune","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Nabil","middleName":"","lastName":"Chakroune","suffix":""},{"id":277480205,"identity":"e4b6f816-a5d6-4065-9d79-c6aace938dde","order_by":2,"name":"Mouna Amara","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Mouna","middleName":"","lastName":"Amara","suffix":""},{"id":277480206,"identity":"c14a7ca2-e638-45ef-abf3-c8ee0fd3e0e6","order_by":3,"name":"Habib Boudaa","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Habib","middleName":"","lastName":"Boudaa","suffix":""},{"id":277480207,"identity":"92ac81ce-31b8-467d-a878-f3fea2956884","order_by":4,"name":"Ibrahim Ayad","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Ibrahim","middleName":"","lastName":"Ayad","suffix":""},{"id":277480208,"identity":"107c18c7-8d3e-46c7-92ff-2831c6e5d063","order_by":5,"name":"Souad Mekhfi","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Souad","middleName":"","lastName":"Mekhfi","suffix":""},{"id":277480209,"identity":"581c2929-6f2b-48fd-bcc7-99c2f9254f77","order_by":6,"name":"Rami K. 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23:32:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3989261/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3989261/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":52499772,"identity":"bdd4c822-7c9f-44c9-9e5f-4223b71251c4","added_by":"auto","created_at":"2024-03-12 09:34:22","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":340728,"visible":true,"origin":"","legend":"\u003cp\u003eThe FSW tools before and after heat treatment.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/1c2544baadce1bb172a14ce1.png"},{"id":52499448,"identity":"00592080-f905-4f2d-95ae-8c723899acb6","added_by":"auto","created_at":"2024-03-12 09:26:22","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":283653,"visible":true,"origin":"","legend":"\u003cp\u003eExample of conventional milling machines for friction stir welding.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/e24cb654711d6faced53e11f.png"},{"id":52499443,"identity":"84039daf-ce45-4808-b068-78b0c030550d","added_by":"auto","created_at":"2024-03-12 09:26:22","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":426342,"visible":true,"origin":"","legend":"\u003cp\u003eMounting on the milling machine with a view of the tool above the joint line.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/04360838847dd408adbb19f3.png"},{"id":52500308,"identity":"10ca6836-fbc1-4283-aa6e-8354811149d1","added_by":"auto","created_at":"2024-03-12 09:42:22","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":539833,"visible":true,"origin":"","legend":"\u003cp\u003eClamping configuration used to prevent any movement of the pieces during the welding operation.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/90dafe8f9a316536f8f406ba.png"},{"id":52499444,"identity":"4c5d5bea-8a00-4a16-a229-5dd187b811e7","added_by":"auto","created_at":"2024-03-12 09:26:22","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":815641,"visible":true,"origin":"","legend":"\u003cp\u003e(a) SEIFERT X-ray Generator belonging to the CRD-FA, and (b) Ultrasonic Device with (b.1) Krautkramer Branson USD 15 Type and (b.2) USD-100B Type.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/75bde02f17b2b91b547a0b99.png"},{"id":52500307,"identity":"f81090ad-a2b9-43b2-bc16-faa0b51511d0","added_by":"auto","created_at":"2024-03-12 09:42:22","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":297015,"visible":true,"origin":"","legend":"\u003cp\u003e« ZIG-ZAG» sounding.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/891564f8ba275df1c6c085d1.png"},{"id":52499774,"identity":"98fd0061-3272-41dc-8aa7-da769dae4253","added_by":"auto","created_at":"2024-03-12 09:34:22","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":311921,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Optical microscope \"LEICA DM 2500 M\" and (b) Grain size measurement using the three-circle method.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/f0949a06da7cbc60756aeb1b.png"},{"id":52500563,"identity":"4495d914-544a-41b8-9d3a-7d66caa99467","added_by":"auto","created_at":"2024-03-12 09:50:42","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":306475,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a) \u003c/strong\u003e\"QUANTA 600FEI\" Scanning Electron Microscope and (b) \"X'PERT-PRO\" X-Ray Diffractometer.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/fa2390a2bc171862ecbe580b.png"},{"id":52500558,"identity":"131c900b-f6f1-4a95-8567-631a358cbeca","added_by":"auto","created_at":"2024-03-12 09:50:40","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":460427,"visible":true,"origin":"","legend":"\u003cp\u003eThe 2017AA aluminum plates (6 mm thickness)welded by FSW with the parameters (a) N=950\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/697ac8cbe1f9cb8446c0b81f.png"},{"id":52499779,"identity":"2393d1c3-26ef-495f-af31-2415dae1cadb","added_by":"auto","created_at":"2024-03-12 09:34:22","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":592373,"visible":true,"origin":"","legend":"\u003cp\u003e2017AA aluminum plates (10 mm thickness)welded by FSW using Va=0.6 m/s and θ=2° parameters: (a) N=1050 rpm, (b) N=1250 rpm, and (c) N=1450 rpm.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/75ffa1c405c82d1d81fff8da.png"},{"id":52500561,"identity":"42e717a1-5a1f-42ac-9e26-9212cefb700b","added_by":"auto","created_at":"2024-03-12 09:50:41","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":395655,"visible":true,"origin":"","legend":"\u003cp\u003eVisual identification of different forms of defects during welding with Va=0.6 mm/s, θ=2°.\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/f672963ac1268a271b364f97.png"},{"id":52499780,"identity":"72c0c90d-6dfb-410d-b021-0e38a44b97f3","added_by":"auto","created_at":"2024-03-12 09:34:22","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":501485,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Radiograph of a 6 mm thick sample and (b) 10 mm thick sample, N=1250 RPM, Va=0.6 mm/s, θ=2°.\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/423aef382345dde505754e4e.png"},{"id":52499784,"identity":"fc3bb385-5bc3-4714-afa3-ffb00e0d52a0","added_by":"auto","created_at":"2024-03-12 09:34:22","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":590441,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Examination by right-hand E/R longitudinal wave probe of a 10 mm thick sample welded at 1250 RPM.\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/9dda454ccbf966f80e3c0b56.png"},{"id":52499461,"identity":"2a94186f-52da-4e1b-8cf8-4b2a828097bc","added_by":"auto","created_at":"2024-03-12 09:26:22","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":490671,"visible":true,"origin":"","legend":"\u003cp\u003eExamination by normal incidence contact of a 6 mm thick sample welded at 1250 RPM.\u003c/p\u003e","description":"","filename":"14.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/fac177dabb1945a6547b7855.png"},{"id":52500557,"identity":"4d332a43-7f3e-42b2-b0fa-959f3f8a4f56","added_by":"auto","created_at":"2024-03-12 09:50:39","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":847795,"visible":true,"origin":"","legend":"\u003cp\u003eAngle 70° probe examination of a 10 mm thick sample welded at 1250 RPM.\u003c/p\u003e","description":"","filename":"15.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/fb65b3b1e32279e94c2f79b0.png"},{"id":52499457,"identity":"e1d58d95-d16a-4331-b8bd-d435f69e75f8","added_by":"auto","created_at":"2024-03-12 09:26:22","extension":"png","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":160205,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Illustration of signals corresponding to an internal defect such as an internal tunnel defect in the 10 mm thick piece welded at a speed of 1250 RPM. (b) Defect echo signal.\u003c/p\u003e","description":"","filename":"16.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/469cf6f94c6e1eef71223582.png"},{"id":52499454,"identity":"1035558d-ffe1-49bd-84c4-adeefcc663c4","added_by":"auto","created_at":"2024-03-12 09:26:22","extension":"png","order_by":17,"title":"Figure 17","display":"","copyAsset":false,"role":"figure","size":107528,"visible":true,"origin":"","legend":"\u003cp\u003eAttenuation of the ultrasonic longitudinal wave signal in the FSW welded joint compared to that of the base metal.\u003c/p\u003e","description":"","filename":"17.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/e8448df81fc686f0c1294e06.png"},{"id":52499462,"identity":"4facc517-e978-41b8-a7f7-d12881e6d275","added_by":"auto","created_at":"2024-03-12 09:26:22","extension":"png","order_by":18,"title":"Figure 18","display":"","copyAsset":false,"role":"figure","size":322128,"visible":true,"origin":"","legend":"\u003cp\u003eMicrograph of the FSW welded joint areas at a rotational speed of 950 rpm: (a) Core, (b) ZAT AS, (c) NS-ZATM AS transition, (d) NS-ZATM RS transition,(e) ZAT RS, (f) ZATM RS and (g) ZATM AS and (h) Base Metal.\u003c/p\u003e","description":"","filename":"18.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/29baba86b4e02f71c4be7857.png"},{"id":52500312,"identity":"f8510ae3-de1c-433d-aa86-880b5bc892fc","added_by":"auto","created_at":"2024-03-12 09:42:22","extension":"png","order_by":19,"title":"Figure 19","display":"","copyAsset":false,"role":"figure","size":341887,"visible":true,"origin":"","legend":"\u003cp\u003eMicrograph of the joint areas welded by FSW at a speed of 1050 rpm: (a) Core, (b) ZAT AS, (c) ZAT RS, (d) Transition NS-ZATM AS, (e) ZATM AS and (f) ZATM RS.\u003c/p\u003e","description":"","filename":"19.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/b65d9a6890654cd6c6521aae.png"},{"id":52499463,"identity":"a2d62bf6-ccf6-4d57-b281-fb4e267cab05","added_by":"auto","created_at":"2024-03-12 09:26:22","extension":"png","order_by":20,"title":"Figure 20","display":"","copyAsset":false,"role":"figure","size":400639,"visible":true,"origin":"","legend":"\u003cp\u003eMicrograph of the FSW welded joint areas at a rotational speed of 1250 rpm: (a) Core, (b) ZAT AS, (c) ZAT RS, (d) Transition NS-ZATM AS, (e) ZATM AS and (f) ZATM RS.\u003c/p\u003e","description":"","filename":"20.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/092a92d6e737245fd45ea35d.png"},{"id":52500559,"identity":"e92abd8e-05f9-42fa-9be6-deea8b48ec3b","added_by":"auto","created_at":"2024-03-12 09:50:40","extension":"png","order_by":21,"title":"Figure 21","display":"","copyAsset":false,"role":"figure","size":71377,"visible":true,"origin":"","legend":"\u003cp\u003eResults of the XRD analysis on: (a) welded joint, (b) base metal.\u003c/p\u003e","description":"","filename":"21.png","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/d2806f4dab1e0399d4a7b397.png"},{"id":52500637,"identity":"1d5eab3a-c831-45b2-ab11-35c65f84fc65","added_by":"auto","created_at":"2024-03-12 09:50:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8323162,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3989261/v1/bde0d11a-f0c4-4273-bc3f-f6bf71653b93.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003ePreparation, Inspection, and Optimization of Rotary Friction Welding Parameters for 2017aa Aluminum Alloy Specimens.\u003c/p\u003e","fulltext":[{"header":"I. INTRODUCTION AND OVERVIEW ON THE BACKGROUD","content":"\u003cp\u003eIn aeronautics, the weight factor is crucial. The welding process known as Friction Stir Welding (FSW), developed by Thomas Wayne at the British welding institute, The Welding Institute (TWI) [1], has a significant advantage in terms of reducing the weight of structures, which directly influences the fuel consumption of aircraft. This technique enables a solid-state assembly that facilitates the welding of alloys known for poor weldability using conventional fusion processes (TIG, GMAW, etc.), making its use highly valuable [2-6]. The base materials to be welded are never melted during the welding operation. The principle of this welding technology is based on the physical principle of friction welding in rotation. The major difference is the use of a rotating tool whose role is to stir and mix the material at the interface of the parts to be joined. The welding is done in the solid state (in a \u0026quot;pasty\u0026quot; state). More generally, FSW welding is particularly suitable for alloys with low melting points and high hot ductility, such as aluminum, magnesium, and even copper alloys [7-11].\u003c/p\u003e\n\u003cp\u003eThe FSW welding process offers an alternative to the systematic riveting of various assemblies. Furthermore, it allows for a reduction in assembly time compared to automated riveting. An application has already emerged in the production of wing and fuselage parts. Indeed, the American company Eclipse Aviation Corporation has integrated the FSW process into the manufacturing of a jet, the Eclipse 500, thereby eliminating 60% of rivets [12].\u003c/p\u003e\n\u003cp\u003eSeveral parameters influence the movement of material and the microstructural and mechanical characteristics of the weld. The most influential parameters are the rotation and feed rates of the welding tool. Additionally, the tool itself, its geometry, the material it\u0026apos;s made of, and its hardness also play a crucial role. Other parameters include the force applied to the tool, the angle of tool tilt, and the depth of the tool plunge into the material to be welded. The tool serves two main functions. Firstly, it generates friction against the workpiece, resulting in heat concentration that softens the material, and it facilitates the movement of material from the advancing side of the weld to the retreating side. The design of the tool significantly impacts the microstructure uniformity and, consequently, the mechanical properties of the joint. Threaded pins and concave shoulders are commonly used as they better knead the material and prevent overflow and burrs. Three distinct tool configurations are distinguished for Friction Stir Welding (FSW): the conventional tool, the retractable pin tool, and the double-shoulder tool, also known as the \u0026quot;Bobbin tool\u0026quot; or \u0026quot;Self tool\u0026raquo;. Rotation and feed rates are two critical parameters in Friction Stir Welding, as they determine the weld quality. The tool rotation rate, \u0026omega;, is expressed in rotations per minute (rpm), while the tool feed rate, \u0026gamma;, is expressed in millimeters per minute (mm/min). In this process, unlike conventional continuous processes, the welding occurs \u0026quot;blindly,\u0026quot; meaning that the shoulder and pin completely conceal the underlying phenomena of the weld. The lack of direct visual observation poses challenges in parameter determination and real-time monitoring of the ongoing welding. Consequently, the necessity for a monitoring and control system for real-time parameter management arises. Furthermore, at the end of the weld bead, the tool withdrawal leaves a hole that cannot be simply filled through FSW. For open linear welds, this requires the implementation of plugs that need to be removed at the beginning and end of the weld bead [13].\u003c/p\u003e\n\u003cp\u003eThe mechanical and thermal phenomena in all fusion welding processes lead to a modification of the microstructure of the base material and its mechanical properties. This drawback arises from the metallurgical phenomena that occur during welding and which represent the location of stress concentration in the case of external stresses. The first metallurgical phenomenon is the modification of the material\u0026apos;s precipitation state. The second is the recrystallization of the material. In contrast, the Friction Stir Welding (FSW) process allows obtaining less significant metallurgical modifications compared to other processes, caused by the various phase changes during welding. A cross-sectional cut of the welded joint reveals different zones in which the material is thermally affected (Heat Affected Zone HAZ) or thermomechanically affected (Thermo Mechanical Affected Zone TMAZ). Each zone depends on the attained temperature, metallurgical changes, and deformations undergone during the welding process.\u003c/p\u003e\n\u003cp\u003eThe exothermic and endothermic peaks present in this figure correspond to the precipitation reactions illustrated in the equilibrium phase diagram of stable and metastable phases within the Al-Cu system region, and they are evenly distributed across the spectrum. These precipitation phenomena are clearly revealed by the Differential Scanning Calorimetry (DSC) thermogram obtained from the base metal. The microstructure is similar to that observed in the base metal. It should be noted that the different precipitates identified in this study are the same as those reported in other research works for the Al-Cu system.\u003c/p\u003e\n\u003cp\u003eIn this section, studies of the FSW process carried out by the research group at the Algerian Research and Development Center (CRD / FA) were subjected to in-depth analysis: Mimouni et al. [14] conducted a comparative study between FSW and LAFSW (Laser Friction Stir Welding) using the FLUENT software. They concluded that the flow velocity around the pin increases when the number of stirring parts (agitation pieces) rises. Additionally, preheating before the tool pass plays a beneficial role in the welding quality. Chekroun et al. [15] performed an experimental study on the friction stir welding of the 2017AT451 aluminum alloy, varying the tool rotation speed from 950 to 1250 rpm. The results showed that the increase in tool rotation speed leads to significant growth of grains in the Heat-Affected Zone (ZAT) and enhances recrystallization of the Near-Zone (NZ) microstructure.\u003c/p\u003e\n\u003cp\u003eIn the same context, the experimental thermal cycles indicate that the temperature peak reached during the welding process is entirely sufficient to trigger precipitation phenomena for 2017AA. Mimouni et al. [16] studied the flow behavior around a tool used in the FSW process. The heat generated during FSW must be sufficiently ample to soften, mix, and blend the material. A reasonable agreement between the temperature values obtained from the model and those measured in the experiment is observed. Friction Stir Welding (FSW) is a solid-state welding process that was invented in 1991 by The Welding Institute (TWI), United Kingdom [17]. While dead weight processing is often used as a technique for welding aluminum alloys [18,19], it has also been employed for welding numerous other metals such as magnesium alloys [20,21], titanium alloys [22,23], and matrix composite metals [24,25]. Furthermore, similar or different materials of varying thicknesses can be welded using this method. This section summarizes the recent experimental and numerical research on the FSW process.\u003c/p\u003e\n\u003cp\u003eMotivated with the above recent reported technologies in the field FSW of aluminum, we are addressing in this work the development of a local design of a FSE tool that are characterized by smooth operations and better control of the process parameters.\u003c/p\u003e"},{"header":"II. EXPERIMENTAL STUDIES","content":"\u003cp\u003eIn this section, the various experimental and numerical methods are described in the present study. Firstly, the mechanical tests conducted and the procedures followed to determine, in particular, the mechanical behaviors under tensile, flexural, and fatigue loading conditions are presented. Secondly, the methodology adopted for the numerical simulation of this type of Friction Stir Welding (FSW) to determine the heat flow behavior is discussed.\u003c/p\u003e\n\u003ch2\u003eII.1 Materials studied\u003c/h2\u003e\n\u003cp\u003eDuring the course of this study, a base material was investigated: an alloy from the 2000 series (Aluminum-Copper). The alloy used for welding exhibits a structural hardening process known as \u0026quot;Age-hardening\u0026quot; (AU4G-1). In the context of this work, the alloy was examined in a metallurgical T6 condition, which corresponds to the as-received state of the sheet. Chemical analyses were conducted at the Materials Laboratory of the Air Force Research and Development Center \u0026quot;CRD-FA\u0026quot; - Dar El Beida. X-ray fluorescence spectrometry was employed using a mass spectrometer designed for light alloys, branded as \u0026quot;SPETRO.\u0026quot; The chemical composition of the 2017AA alloy is indicated in Table 1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable1.\u003c/strong\u003eChemical composition of the base metal (2017AA) determined by X-rays.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"564\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.283185840707965%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eElements\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSi\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.31858407079646%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFe\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCu\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.31858407079646%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.31858407079646%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMg\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.31858407079646%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eZn\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTi\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCr\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAl\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.283185840707965%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;% (Weight)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.31858407079646%\" valign=\"top\"\u003e\n \u003cp\u003e0.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.31858407079646%\" valign=\"top\"\u003e\n \u003cp\u003e0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.31858407079646%\" valign=\"top\"\u003e\n \u003cp\u003e2.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.31858407079646%\" valign=\"top\"\u003e\n \u003cp\u003e5.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.08849557522124%\" valign=\"top\"\u003e\n \u003cp\u003e89.09\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eEnergy Dispersive X-Ray Fluorescence (EDX) analysis enables the qualitative and quantitative elemental composition determination of a sample by measuring the energies of X-ray photons emitted from the region of the sample bombarded by an electron beam using a detector. Metallic elements emit X-rays at characteristic energies when subjected to high-energy X-ray irradiation. The X-ray spectrum emitted by the material is indicative of the sample\u0026apos;s composition. By analyzing this spectrum, one can deduce the elemental composition, i.e., the mass concentrations of the elements. One of the samples took the form of 6 mm thick rolled sheets, while another sample comprised 10 mm thick rolled sheets that were used for creating welded joints through Friction Stir Welding (FSW).\u003c/p\u003e\n\u003ch2\u003eII.2 Preparation of the welding plates\u003c/h2\u003e\n\u003cp\u003ePlates measuring 100 mm in width and 250 mm in length were cut from a sheet of 2017AA aluminum of thicknesses 6 mm and 10 mm using an industrial saw. In order to eliminate the deformations caused by the cutting process, the plates underwent a second stage of machining on a milling machine, treating both sides. These steps ensured that the plates were free from distortions at the edges, thereby achieving uniform joints.\u003c/p\u003e\n\u003ch2\u003eII.3 welding tools\u003c/h2\u003e\n\u003cp\u003eAll the tools are made of H11 steel (tool steel Z38CDV5.1), which has a higher melting temperature and hardness compared to aluminum. Table 2 displays the chemical composition of this steel.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003eChemical composition of tool steel Z38CDV5.1.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"617\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.857605177993527%\"\u003e\n \u003cp\u003e\u003cstrong\u003eelements\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.605177993527508%\"\u003e\n \u003cp\u003e\u003cstrong\u003eC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.223300970873787%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSi\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.605177993527508%\"\u003e\n \u003cp\u003e\u003cstrong\u003eV\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.223300970873787%\"\u003e\n \u003cp\u003e\u003cstrong\u003eCr\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.679611650485437%\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.679611650485437%\"\u003e\n \u003cp\u003e\u003cstrong\u003eFe\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.223300970873787%\"\u003e\n \u003cp\u003e\u003cstrong\u003eNi\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.223300970873787%\"\u003e\n \u003cp\u003e\u003cstrong\u003eCu\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.679611650485437%\"\u003e\n \u003cp\u003e\u003cstrong\u003eMo\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.857605177993527%\"\u003e\n \u003cp\u003e% weight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.605177993527508%\"\u003e\n \u003cp\u003e0.393\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.223300970873787%\"\u003e\n \u003cp\u003e0.110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.605177993527508%\"\u003e\n \u003cp\u003e0.293\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.223300970873787%\"\u003e\n \u003cp\u003e4.567\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.679611650485437%\"\u003e\n \u003cp\u003e0.926\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.679611650485437%\"\u003e\n \u003cp\u003e92.054\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.223300970873787%\"\u003e\n \u003cp\u003e0.165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.223300970873787%\"\u003e\n \u003cp\u003e0.076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.679611650485437%\"\u003e\n \u003cp\u003e1.016\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eII.3.1 Realization of the FSW tool\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTools were manufactured to perform the butt welding of plates. These tools have the same shoulder and pin geometry. The pin lengths are 5.80 mm and 9.80 mm, respectively, in order to weld plates of different thicknesses (6 mm and 10 mm).\u003c/p\u003e\n\u003cp\u003eThe characteristics of the welding tools are shown in Table 3, and Figure 1 displays the tools before and after heat treatment. The FSW welding tool undergoes heat treatment (heated up to 1010\u0026deg;C, held for 20 minutes, and then rapidly cooled in oil) [26]. The hardness before and after quenching is 30 and 54 HRc, respectively.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3.\u003c/strong\u003e Characteristics and dimensions of FSW welding tools used to weld alloy 2017AA.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"614\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.723577235772357%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eAlloy\u003c/p\u003e\n \u003cp\u003e2017AA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.268292682926829%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eSeal type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"26.178861788617887%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eShoulder\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"46.829268292682926%\" colspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003ePawn\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"20.982142857142858%\" valign=\"top\"\u003e\n \u003cp\u003eDiameter (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.732142857142858%\" valign=\"top\"\u003e\n \u003cp\u003eType\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.982142857142858%\" valign=\"top\"\u003e\n \u003cp\u003eDiameter (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.964285714285715%\" valign=\"top\"\u003e\n \u003cp\u003eType\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"26.339285714285715%\" valign=\"top\"\u003e\n \u003cp\u003eLength (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.752442996742673%\" valign=\"top\"\u003e\n \u003cp\u003ePlates 6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.283387622149837%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eButt welding\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.309446254071661%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.749185667752442%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eConcave\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.309446254071661%\" valign=\"top\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.37785016286645%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eWith thread\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.218241042345277%\" valign=\"top\"\u003e\n \u003cp\u003e5.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"33.95638629283489%\" valign=\"top\"\u003e\n \u003cp\u003ePlates 10 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"29.28348909657321%\" valign=\"top\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"36.7601246105919%\" valign=\"top\"\u003e\n \u003cp\u003e9.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003ch2\u003e\u003cem\u003eII.3.2 Welding machines\u003c/em\u003e\u003c/h2\u003e\n\u003cp\u003eCurrently, the main machines used for Friction Stir Welding (FSW) are modified milling machines, machines designed specifically for FSW, and robots. In this study, welding was performed on a conventional milling machine with a maximum rotation speed of 2000 RPM and a feed rate of 900 mm/min. This machine is located in the workshops of the Aeronautical Equipment Renovation and Maintenance Company (ERMA-A\u0026eacute;ro). Modifications were necessary to adapt the table for setting up a test bed to carry out the welds.\u003c/p\u003e\n\u003ch2\u003e\u003cem\u003eII.3.3 Implementation phase of the welding technique\u003c/em\u003e\u003c/h2\u003e\n\u003cp\u003eThe welding was carried out at the ERMA-Aero level. Before welding, the sheets need to be cut to the same dimensions. The first one is positioned so that the edge to be welded is parallel to the advance of the pin during welding. Then, the two sheets are clamped. Figure 3 shows a 5 cm thick steel plate placed beneath the material to thermally isolate it from the support and verify flatness. Subsequently, the welding parameters, rotation speed, and welding speed are programmed, and the head\u0026apos;s inclination is adjusted. The main steps used during welding are as follows:(i) Position the tool above the plates at the beginning of the joint and tilt the tool by 2 degrees; therefore, it is necessary to clamp the pieces laterally and vertically to prevent them from lifting or separating during welding. Figure 4.a presents the possible clamping configuration used to prevent any movement of the pieces during the welding operation.(ii) Initiate and adjust the rotation of the machine\u0026apos;s head, as shown in Figure 4.b (three rotation speeds for each thickness);(iii) Submerge the tool and wait for 2 seconds [27]. This delay is necessary to achieve thermal balance (Figure 4.c);(iv) Start moving the tool at a feed rate of 0.6 mm/s (Figure 4a.c), and(v) Raise the tool at the end of the joint and stop the machine. The length of the plates was oriented in the rolling direction so that the welded joint is also in the rolling direction (Figure 4.d).\u003c/p\u003e\n\u003cp\u003eThe plates were welded with the parameters mentioned in Table 4. For both thicknesses, the tool feed rate and the tilt angle were fixed, and the rotation speed was varied to study its effect on FSW welding. The choice of rotation speeds was made based on a multitude of preliminary tests. There are two types of welds: cold welds, where the rotation speed/feed rate ratio is less than 1 rev/mm, and hot welds, where this ratio is greater than 1 tr/mm [28]. In our case, the ratio ranges from 26 to 40 tr/mm, thus referring to a hot weld.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4.\u0026nbsp;\u003c/strong\u003eWelding parameters and sizes of welded plates.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"638\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"12.539184952978056%\"\u003e\n \u003cp\u003eAlloy 2017A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.203761755485893%\"\u003e\n \u003cp\u003eLength x length\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.344827586206897%\" valign=\"top\"\u003e\n \u003cp\u003eTests\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.771159874608152%\" valign=\"top\"\u003e\n \u003cp\u003eRotation speed (rpm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.830721003134796%\" valign=\"top\"\u003e\n \u003cp\u003eFeed rate (mm/min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.912225705329154%\"\u003e\n \u003cp\u003eTilt angle (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.398119122257054%\" valign=\"top\"\u003e\n \u003cp\u003eReport N/Va (tr/mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"12.539184952978056%\" rowspan=\"3\"\u003e\n \u003cp\u003ePlates 6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.203761755485893%\" rowspan=\"3\"\u003e\n \u003cp\u003e250 x 100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.344827586206897%\" valign=\"top\"\u003e\n \u003cp\u003eTest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.771159874608152%\"\u003e\n \u003cp\u003e950\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.830721003134796%\" rowspan=\"6\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.912225705329154%\" rowspan=\"6\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.398119122257054%\" valign=\"bottom\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.239436619718308%\" valign=\"top\"\u003e\n \u003cp\u003etest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"37.67605633802817%\"\u003e\n \u003cp\u003e1050\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.08450704225352%\" valign=\"bottom\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.239436619718308%\" valign=\"top\"\u003e\n \u003cp\u003etest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"37.67605633802817%\"\u003e\n \u003cp\u003e1250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.08450704225352%\" valign=\"bottom\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.35357917570499%\" rowspan=\"3\"\u003e\n \u003cp\u003ePlates 10 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.0412147505423%\" rowspan=\"3\"\u003e\n \u003cp\u003e250 x 100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.316702819956616%\" valign=\"top\"\u003e\n \u003cp\u003etest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.210412147505423%\"\u003e\n \u003cp\u003e1050\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.07809110629067%\" valign=\"bottom\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.239436619718308%\" valign=\"top\"\u003e\n \u003cp\u003etest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"37.67605633802817%\"\u003e\n \u003cp\u003e1250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.08450704225352%\" valign=\"bottom\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.239436619718308%\" valign=\"top\"\u003e\n \u003cp\u003etest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"37.67605633802817%\"\u003e\n \u003cp\u003e1450\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.08450704225352%\" valign=\"bottom\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003ch2\u003eII.3 Means of quality control of welds\u003c/h2\u003e\n\u003cp\u003eThe welds were inspected using three non-destructive methods: visual inspection, radiography, and ultrasonic testing. The examination focused on the weld beads and the imprint (crevice) left by the tool at the end of welding. These examinations serve to ascertain the potential presence of surface or internal defects.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eII.3.1 Rayons X analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe generator used for radiographic inspection employs an X-ray tube with a copper (Cu) cathode, manufactured by SEIFERT, with a maximum power of 900 kW (Figure 5), using settings specific to aluminum. The 6 mm thick FSW (Friction Stir Welding) joint inspected through radiography is the one achieved at a rotational speed of 1250 rpm. A 200 mm longitudinal weld is located at the center of the two plates. The joint undergoes radiographic testing to detect potential defects. These defects are identified through observation of the digitized radiographic image. The other two configurations (welded joint at 950 rpm and welded joint at 1050 rpm) are not subjected to radiographic examination due to a lack of radiographic films at the CRD-FA level. The same applies to the joint made on 10 mm thick plates; only the joint welded at a rotational speed of 1250 rpm is inspected using radiography. The other two configurations are not inspected via radiography (welded joint at 1050 rpm and welded joint at 1450 rpm).\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eII.3.2 Ultrasonic inspection.\u0026nbsp;\u003c/strong\u003eUltrasonic inspection of FSW welds was conducted at the Aeronautical Structures Fatigue and Reliability Laboratory (CRD-FA). Two types of testing methods were employed. The first involved immersion testing using a tank designed for laboratory characterization. The second method utilized contact testing.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eII.3.3 Exam by echography-Ultrasonore(E/R).\u003c/strong\u003eTwo ultrasonic devices of the brand KRAUTKRAMER-Branson USD 15 (Figure 5.b.1) and USD-100B type (Figure 5.b.2) are used for defect detection in emission/reception mode.\u003c/p\u003e\n\u003cp\u003eFor the surface wave survey, two probes were used: one as the transmitter (Harisonic ABM 0506 90\u0026deg; ST 5.0 MHz) and the other as the receiver (Panametrics NDT 5 MHz-0.5\u0026rsquo;). They are intended for transmission surveys. For internal defect detection, two angle probes were employed, both used in contact mode: the MWB-70 probe (f = 4 MHz) and the MWB-45 probe (f = 4 MHz). Additionally, two transducers were used: one for longitudinal wave transmission, a Panametrics A120R (62654) with a frequency of 7.5/0.5\u0026rsquo;, and the other for shear wave transmission, a Panametrics V155 (174913) with a frequency of 5.0/0.5\u0026rsquo;. Following the calibration of the ultrasonic equipment, the applied ultrasonic scanning is carried out in a manner that covers the entire surface potentially containing any defects. To achieve this, a \u0026quot;ZIG-ZAG\u0026quot; scanning approach was chosen (Figure 6).\u003c/p\u003e\n\u003cp\u003eThe scanning is performed on both sides of the weld in order to locate the maximum of defects. The area of the scanning zone is traversed using two types of movements. (i) A Zig-Zag motion parallel to the axis of the weld with a step that does not exceed the width of the probe, and (ii) A pivoting motion: While approaching and moving away from the welded joint, the probe must oscillate at an angle of 10 to 15\u0026deg; on each side of the normal to the axis of the joint [30-31]. With this type of movement, it is possible to distinguish between volumetric defects and linear defects.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eII.4. Observations and analyzes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis paragraph aims to present the various experimental techniques that were applied during this study in order to characterize the microstructure of welded joints at different scales. The description of the methods will be carried out considering observation scales that become increasingly finer.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eII.4.1 Optical Microscopy\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe friction stir welding process results in the formation of different zones, with sizes on the order of a few millimeters. Optical microscopy is employed to conduct initial examinations of the various microstructures in the obtained joints. These observations were carried out using a \u0026ldquo;Leica DM 2500 M\u0026rdquo; optical microscope connected to a microcomputer equipped with \u0026ldquo;Leica Application Suite LAS\u0026rdquo; image acquisition software for image transfer and processing (Figure 7.a). To characterize the microstructure of the welded joints and identify the different zones, a Keller\u0026rsquo;s reagent etching was performed. Prior to etching, the sample must be mechanically polished using 240-grit paper to achieve a mirror finish with 3\u0026mu;m diamond paste. The metallographic etching involves immersing the sample in Keller\u0026rsquo;s reagent (2.5 ml nitric acid HNO\u003csub\u003e3\u003c/sub\u003e, 1 ml hydrofluoric acid HF, 1.5 ml hydrochloric acid HCl, and 95 ml distilled water) for 10 seconds, followed by rinsing with distilled water.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eII.4.2 Measurement of grain size\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo measure the grain size, we employed the three-circle method. Images captured by the optical microscope are digitized and subsequently analyzed using an image acquisition software, \u0026quot;Leica Application Suite LAS.\u0026quot; Figure 7b illustrates an example of the analysis of these images.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eII.4.3 Scanning Electron Microscopy (SEM)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eScanning electron microscopy observations were performed to complement the optical microscopy observations and to analyze fracture features after tensile and fatigue tests. These observations were conducted to evaluate the mechanical behavior of the tested materials. Additionally, due to the attainable magnifications, scanning electron microscopy allowed for a more precise examination of the microstructure of welded joints during the various tests conducted in this study. Sample polishing was carried out when a flat surface was required. In the case of fracture feature analysis, samples were observed without specific preparation. Micrographic examinations of the sample surfaces were conducted using a QUANTA 600FEI scanning electron microscope available at the Laboratory of Materials Engineering (LGM) at the Polytechnic Military School of Bordj El Bahri (EMP) (Figure 8). The microscope was equipped with an infrared camera capable of producing digital images.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eII.4.4 X-ray Diffraction (XRD)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eX-ray diffraction was utilized to obtain qualitative information about the different phases under investigation. This method provides insights into the crystalline structure and enables the evaluation of lattice parameters or the relative proportions of each phase. The complete set of diffraction spectra was obtained using an \u0026quot;X\u0026apos;PERT-PRO\u0026quot; diffractometer (Figure 8b). Monochromatic X-ray radiation was generated using a copper anticathode, and the K\u0026alpha;1 (1.5406 \u0026Aring;) and K\u0026alpha;2 (1.54443 \u0026Aring;) lines were isolated through absorption discontinuity with the use of a germanium filter. The tube operated with the following power settings: V = 45 kV, I = 40 mA. Table 5 summarizes the measured mechanical characteristics of the 2017AA alloy.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5.\u003c/strong\u003e Mechanical characteristics of the 2017AA alloy.\u003c/p\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"609\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.098360655737704%\" rowspan=\"2\"\u003e\n \u003cp\u003e2017AA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.049180327868854%\"\u003e\n \u003cp\u003e\u0026rho; (kg/m3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.98360655737705%\"\u003e\n \u003cp\u003e\u0026Nu;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.40983606557377%\"\u003e\n \u003cp\u003eE (GPa)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.40983606557377%\"\u003e\n \u003cp\u003e\u0026lambda; (GPa)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.049180327868854%\"\u003e\n \u003cp\u003e\u0026mu; (GPa)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.4622030237581%\"\u003e\n \u003cp\u003e2741.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.47084233261339%\"\u003e\n \u003cp\u003e0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.302375809935207%\"\u003e\n \u003cp\u003e72.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.302375809935207%\"\u003e\n \u003cp\u003e58.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.4622030237581%\"\u003e\n \u003cp\u003e27.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"III. RESULTS AND DISCUSSION","content":"\u003cp\u003e\u003cstrong\u003eIII.1 Welding of 6mm and 10mm Thick Sheets\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThree welding operations were performed on the 6mm thick plates, with rotation speeds of 950, 1050, and 1250 RPM, and a constant feed rate of 0.6 mm/s. The inclination angle is 2\u0026deg;, as shown in Figure 9. Symbols (a, face) represent the side of the weld bead, and (a, side) represents the opposite side. In Figure (a), the welding was conducted at a rotation speed of N = 950 RPM, and an acceptable joint quality was achieved with striations on the joint surface\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFigure 9.b illustrates the weld bead obtained at a rotational speed of 1050 rpm. A relatively smooth and defect-free bead is observed, with a width equal to the diameter of the shoulder. This bead exhibits good visual quality. Two experiments were conducted using a rotational speed of 1250 rpm on 6 mm plates. Figure 9.c depicts a smooth bead surface with a well-distributed pattern of ridges resulting from the increased rotational speed, which generates a significant amount of heat, facilitating material mixing.\u003c/p\u003e\n\u003cp\u003eAs is the case for the 6 mm thick plates, three welding operations were performed on the 10 mm thick plates, with rotation speeds of 1050, 1250, and 1450 rpm and a constant feed rate of 0.6 mm/s. The tilt angle is 2\u0026deg; (Figure 10). Referring to Figure 10.a, for the welding of the 10 mm thick plates with a rotation speed of 1050 rpm, a lack of material mixing is observed due to a low rotation speed in relation to the plate thickness. The joint was formed, but with tunnel-type defects on the surface. This defect occurs when the operating conditions are cold, leading to insufficient material mixing. Two tests were conducted with a rotation speed of 1250 rpm on the 10 mm plates. It can be seen that for this configuration, the quality of the joint obtained is better compared to that obtained with a rotation speed of 1050 rpm (Figure 10.b). Figure 10.c shows the weld bead obtained with a rotation speed of 1450 rpm on the 10 mm plates, revealing an acceptable bead width equal to the diameter of the shoulder. Note that in some cases, the hole left by the tool during the upward phase is filled by the breakage of the tool pin at the end of the welding operation, as shown in Figure 10.c. Therefore, the operation concluded with a burnt tool and without a pin. The weld beads obtained after welding on the used aluminum alloy 2017AA demonstrated that the rotation speed and thickness influence the quality of the weld. It is observed that the welds on the 6 mm thick plates are better compared to those on the 10 mm thick plates, and as the rotation speed increases, the weld quality improves. Once the welds are completed, it is necessary to evaluate the different joints obtained.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.2 Analysis of Defect Generation Based on Operating Parameters\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe encountered defects align with those described in Chapter I of the literature review for other aluminum alloy compositions. The identified defects for each welding configuration are presented below.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.2.1 Defects identified by visual inspection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor all welds, the width of the imprint left by the tool during the penetration phase is the same as that of the weld bead. If the tool retracts slightly, the mixing beneath the pin becomes inadequate, leading to the occurrence of the partial penetration defect (Figure 11.a).\u003c/p\u003e\n\u003cp\u003eDuring welding, the tool penetrates into the material, resulting in excessive tool penetration. This leads to the formation of excessive burrs (Figure 11.b), consequently causing a reduction in the weld section. This burr corresponds to the surplus material displaced by the tool as it penetrates. This type of defect is referred to as \u0026quot;Ribbon flash\u0026quot;. Surface defects such as insufficient marking of the shoulder and scratches, left on the surface by the passage of the shoulder over the weld bead, are shown in Figure 11.c. For 10 mm thick plates, with a low rotational speed of 1050 rpm, a groove-type defect is observed on the joint surface, originating from insufficient heat input provided by the tool (Figure 11.d).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.2.2. identified through radiographic examination\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe 6 mm thick plates do not contain internal defects. Figure 12.a shows an example of a radiographic examination of the weld joint of the plates at 1250 rpm. Only the streaks left by the passage of the tool are observed in this radiographic image.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor a thickness of 10mm, this configuration exhibits an internal tunnel defect. This corresponds to a lack of material consolidation at the shoulder passage. The radiograph of a bead (Figure 12.b) shows this defect. It can appear at the beginning or in the middle of the weld after a few millimeters of welding. In our study, its origin is attributed to a mixing flaw. The weld bead presents a good surface condition, but internally, upon radiographic examination, an internal tunnel defect is observed along the joint, visible to the naked eye in the digitized image.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.2.3 Defects identified through ultrasonic examination\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo detect potential defects, it is necessary to examine the weld over its entire cross-section and along its entire length.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.2.3.1 Surface defect detection.\u003c/strong\u003e All welds are examined using ultrasonic testing to detect surface defects. Only two configurations contained defects: lack of penetration defects on 10 mm thick plates welded at a rotation speed of 1450 rpm, and lack of marking defects on the shoulder, also in 10 mm thick plates welded at 1250 rpm.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.2.3.2 Internal defect scanning using straight E/R probe.\u003c/strong\u003e Among the techniques employed for detecting internal defects in weld joints, a straight probe with an emitter-receiver relay for longitudinal wave transmission at 10MHz/25 was used. Figure 13.a illustrates an example of examination on 10 mm thick welded plates. In this configuration, the opposite side was examined due to its good surface condition.\u003c/p\u003e\n\u003cp\u003eFor 10 mm thick plates welded at 1250 RPM, the presence of a defect is observed (Figure 13.a). The depth of this defect is 5.59 mm relative to the opposite surface of the joint. Figure 13.b displays an oscillogram received by the probe in a non-welded area on 6 mm thick plates. According to Figure 14, there is no change in the oscillogram provided by the ultrasonic E/R probe compared to the reference oscillogram. This demonstrates the absence of internal defects in the 6 mm thick sample joint.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.2.3.3. Internal defect assessment through oblique incidence contact.\u003c/strong\u003e The previous result from section V.3.3.2 is corroborated by an oblique incidence examination using a 70\u0026deg; angle probe and a Krautkramer Branson USD 15 ultrasonic device, after its adjustment. Following a Zig-Zag type scanning, the defect is localized along the joint. Its depth is directly displayed on the device (Figure 15), measuring approximately 5.18 mm relative to the joint surface. Figure 16 illustrates an example of defect localization within the 10 mm thick joint welded at a speed of 1250 RPM. The presence of two defect echoes is noted due to the complex geometry of the internal defect.\u003c/p\u003e\n\u003cp\u003eTable 6 summarizes the synthesis of non-destructive examinations conducted on the weld joints for the two thicknesses used.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 6.\u0026nbsp;\u003c/strong\u003eTypes of defects present at the FSW joint level.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"10.749185667752442%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003ePlates\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.592833876221498%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eRotational speed\u003c/p\u003e\n \u003cp\u003eN (rpm))\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"64.65798045602605%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eType of defect\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"64.23173803526448%\" valign=\"top\" style=\"width: 35.8535%;\"\u003e\n \u003cp\u003eSurface defect\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"35.768261964735515%\" valign=\"top\" style=\"width: 27.5215%;\"\u003e\n \u003cp\u003eD\u0026eacute;faut interne\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"10.749185667752442%\" rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e6mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.592833876221498%\" valign=\"top\"\u003e\n \u003cp\u003e950\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"41.530944625407166%\" valign=\"top\" style=\"width: 35.8535%;\"\u003e\n \u003cp\u003eNo defects\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.127035830618894%\" valign=\"top\" style=\"width: 27.5215%;\"\u003e\n \u003cp\u003eNo defects\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.554744525547445%\" valign=\"top\"\u003e\n \u003cp\u003e1050\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"46.53284671532847%\" valign=\"top\" style=\"width: 35.8535%;\"\u003e\n \u003cp\u003eLack of shoulder marking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.912408759124087%\" valign=\"top\" style=\"width: 27.5215%;\"\u003e\n \u003cp\u003eNo defects\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.554744525547445%\" valign=\"top\"\u003e\n \u003cp\u003e1250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"46.53284671532847%\" valign=\"top\" style=\"width: 35.8535%;\"\u003e\n \u003cp\u003eNo defects\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.912408759124087%\" valign=\"top\" style=\"width: 27.5215%;\"\u003e\n \u003cp\u003eNo defects\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"10.749185667752442%\" rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e10mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.592833876221498%\" valign=\"top\"\u003e\n \u003cp\u003e1050\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"64.65798045602605%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eUncontrolled configuration\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.554744525547445%\" valign=\"top\"\u003e\n \u003cp\u003e1250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"46.53284671532847%\" valign=\"top\" style=\"width: 35.8535%;\"\u003e\n \u003cp\u003eLack of shoulder marking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.912408759124087%\" valign=\"top\" style=\"width: 27.5215%;\"\u003e\n \u003cp\u003eTunnel interne\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.554744525547445%\" valign=\"top\"\u003e\n \u003cp\u003e1450\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"46.53284671532847%\" valign=\"top\" style=\"width: 35.8535%;\"\u003e\n \u003cp\u003eLack of penetration\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.912408759124087%\" valign=\"top\" style=\"width: 27.5215%;\"\u003e\n \u003cp\u003eNo defects\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eFigure 17 illustrates the attenuation of longitudinal waves during the inspections of the sound joint and the base metal. Contact inspections on the 6 mm thick piece conducted under the same setting parameters show an attenuation of approximately 27%.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.3 Analysis of Micrography\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this section, the different types of microstructures composing several welded joints are also presented. Indeed, depending on the conditions obtained during welding, such as temperature and deformation rate, the weld can be decomposed into several zones, each having its own characteristics. These observations provide insights into the mechanisms occurring during welding and allow for the comparison of results from different microstructures. The metallography of the majority of welds was conducted to study the microstructure of the four constituent zones of the joint in relation to the tool\u0026apos;s rotation speed. The micrographs of the joint reveal the presence of four distinct zones (weld core denoted as NS, heat-affected zone denoted as ZAT, thermo-mechanically affected zone denoted as ZATM, and the base metal denoted as MB). These zones are the result of the thermal and thermomechanical history of the joint. Presented below is a study aimed at determining the variation of welding zones (ZAT, ZATM, Core) based on the tool\u0026apos;s rotation speeds for 6 mm thick 2017AA aluminum plates welded end-to-end. The provided photos below illustrate the different microstructures of the welded samples. In these images, the advancing side is identified as \u0026quot;AS,\u0026quot; while the retreating side is labeled \u0026quot;RS.\u0026quot; Welds produced by FSW exhibit a highly heterogeneous macrostructure along the weld. Four zones with different microstructures are distinguished in the FSW-welded joint: base metal, weld core, thermo-mechanically affected zones ZATM (AS and RS), and heat-affected zones ZAT (AS and RS).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.3.1 Welded Plates at a Rotation Speed of 950 rpm\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe main difference between the zones is the grain size in each zone. Figure 18 illustrates optical microscope observations of each zone in the FSW-welded joint using 2017AA aluminum alloy at a rotation speed of 950 rpm. The ZAT is the zone where the temperature is sufficiently high to cause overaging of the base metal. It is situated between the base metal and ZATM. In this zone, the grain morphology is nearly the same as that of the base metal (Figure 18.b, e). The ZATM is the zone located between the core and ZAT. In this zone, grain deformation occurs, but the temperature is below critical values to activate dynamic recrystallization mechanisms. Figure 18.c, d show that the transition between the core and ZATM is much sharper on the AS side than on the RS side. This is caused by the deformation gradient. It also shows grains elongated in the direction of metal flow during welding. The joint\u0026apos;s core is the zone where temperature and plastic deformation are sufficiently high to induce grain recrystallization. In this zone, the grain size is approximately 5 microns, significantly smaller than the grain size of the base metal (Figure 18.h). The base metal zone is where the temperature remains below the aging temperature. The metal undergoes no transformation. The micrograph shown in Figure 18.h displays elongated grains due to cold sheet rolling. The figure also indicates the presence of inclusions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.3.2. Welds at a Rotational Speed of 1050 RPM\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFigure 19a illustrates the weld core obtained at a speed of 1050 rpm. A fine microstructure is observed, consisting of grains ranging from 8 to 12 \u0026mu;m. The thermal and mechanical loads experienced during the welding process have led to the complete recrystallization of this region. According to Figure 19d, the thermal and mechanical loads applied result in significant plastic deformation and grain orientation in the direction of the tool\u0026apos;s rotation. The grain size in this region ranges from 50 to 80 \u0026mu;m. It is notable that the grain elongation in the Heat-Affected Zone on the Retreating Side (Figure 19f) is less pronounced than on the Advancing Side (Figure 19e).In the Heat-Affected Zone (HAZ) (Figures 19b, c), both the granular structure and grain size remain consistent with the base material. Thus, the grain size in this zone is similar to that of the base material, ranging from approximately 100 to 130 \u0026mu;m.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.3.3 Welds at a Rotation Speed of 1250 rpm\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe microscopic analysis of the weld joint at 1250 rpm (Figure 20) allows for a clear distinction of the HAZ, HAZM, and Core zones. The effect of the tool\u0026apos;s movement is observed in the kneaded portion due to the change in orientation of deformation planes within the Core and HAZM. The HAZM lies on either side of the Core and undergoes a complex thermal history and plastic deformation induced by the movement of the tool\u0026apos;s pin and its threading. This threading can initiate recrystallization and precipitation phenomena. In the Core, grains become significantly smaller due to intense thermomechanical deformation and dynamic recrystallization effects. Furthermore, the grain size in the Core is always finer than that in the HAZM due to partial recrystallization in the latter, while it is complete in the Core. In the transition zone between the Core and the AS HAZM (Figure 20.d), the boundary between these two zones is clearly marked by the grain size variation\u0026mdash;Core grains are finer than those in the HAZM. Both the HAZ and HAZM are wider in cases of higher rotation speeds. However, the width of the Core remains constant for all welds as it corresponds to the geometry of the tool\u0026apos;s pin.\u003c/p\u003e\n\u003cp\u003eIn conclusion, during the friction-kneading process, the increase in temperature and material deformation caused by the rotation and advancement of the pin result in modifications to the initial microstructure of the plate (the base metal) within the joint.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIII.4. X-ray Diffraction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eX-ray diffraction (XRD) is the most suitable method for revealing the phases present in materials; it is highly sensitive to any disruption of the periodicity of the crystalline lattice. The XRD spectra obtained from two samples, welded and non-welded (base metal), as shown in Figure 21(a) and (b), appear nearly identical but with a greater intensity than in the base metal.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 7.\u0026nbsp;\u003c/strong\u003ePosition of the XRD peaks obtained for a welded sample.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.917491749174918%\" rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026alpha;(Al)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.521452145214521%\" valign=\"top\"\u003e\n \u003cp\u003e2 Theta (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.910891089108912%\" valign=\"top\"\u003e\n \u003cp\u003e38.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.066006600660065%\" valign=\"top\"\u003e\n \u003cp\u003e44.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.561056105610561%\" valign=\"top\"\u003e\n \u003cp\u003e64.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.900990099009901%\" valign=\"top\"\u003e\n \u003cp\u003e78.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.561056105610561%\" valign=\"top\"\u003e\n \u003cp\u003e112.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.561056105610561%\" valign=\"top\"\u003e\n \u003cp\u003e116.51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.34065934065934%\" valign=\"top\"\u003e\n \u003cp\u003e(hkl)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.868131868131869%\" valign=\"top\"\u003e\n \u003cp\u003e111\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.406593406593407%\" valign=\"top\"\u003e\n \u003cp\u003e200\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e220\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.186813186813186%\" valign=\"top\"\u003e\n \u003cp\u003e311\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e331\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e420\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.34065934065934%\" valign=\"top\"\u003e\n \u003cp\u003ed (hkl)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.868131868131869%\" valign=\"top\"\u003e\n \u003cp\u003e2.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.406593406593407%\" valign=\"top\"\u003e\n \u003cp\u003e2.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.186813186813186%\" valign=\"top\"\u003e\n \u003cp\u003e1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e0.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.917491749174918%\" rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026eta; (Al-Zn-Mg-Cu)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.521452145214521%\" valign=\"top\"\u003e\n \u003cp\u003e2 Theta (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.910891089108912%\" valign=\"top\"\u003e\n \u003cp\u003e82.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.066006600660065%\" valign=\"top\"\u003e\n \u003cp\u003e99.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.561056105610561%\" valign=\"top\"\u003e\n \u003cp\u003e137.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.900990099009901%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.561056105610561%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.561056105610561%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.34065934065934%\" valign=\"top\"\u003e\n \u003cp\u003e(hkl)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.868131868131869%\" valign=\"top\"\u003e\n \u003cp\u003e222\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.406593406593407%\" valign=\"top\"\u003e\n \u003cp\u003e400\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e422\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.186813186813186%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.34065934065934%\" valign=\"top\"\u003e\n \u003cp\u003ed (hkl)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.868131868131869%\" valign=\"top\"\u003e\n \u003cp\u003e1.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.406593406593407%\" valign=\"top\"\u003e\n \u003cp\u003e1.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e0.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.186813186813186%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.065934065934066%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 8. \u0026nbsp;\u003c/strong\u003ePosition of the XRD peaks obtained for an unwelded sample (base metal).\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.964664310954063%\" rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026alpha;(Al)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.371024734982333%\" valign=\"top\"\u003e\n \u003cp\u003e2 Theta (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.36749116607774%\" valign=\"top\"\u003e\n \u003cp\u003e38.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.54416961130742%\" valign=\"top\"\u003e\n \u003cp\u003e44.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.250883392226148%\" valign=\"top\"\u003e\n \u003cp\u003e65.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.250883392226148%\" valign=\"top\"\u003e\n \u003cp\u003e78.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.250883392226148%\" valign=\"top\"\u003e\n \u003cp\u003e116.74\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.205298013245034%\" valign=\"top\"\u003e\n \u003cp\u003e(hkl)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.45253863134658%\" valign=\"top\"\u003e\n \u003cp\u003e111\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.673289183222957%\" valign=\"top\"\u003e\n \u003cp\u003e200\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e220\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e311\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e420\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.205298013245034%\" valign=\"top\"\u003e\n \u003cp\u003ed (hkl)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.45253863134658%\" valign=\"top\"\u003e\n \u003cp\u003e2.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.673289183222957%\" valign=\"top\"\u003e\n \u003cp\u003e2.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e0.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.964664310954063%\" rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026eta; (Al-Zn-Mg-Cu)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.371024734982333%\" valign=\"top\"\u003e\n \u003cp\u003e2 Theta (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.36749116607774%\" valign=\"top\"\u003e\n \u003cp\u003e82.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.54416961130742%\" valign=\"top\"\u003e\n \u003cp\u003e99.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.250883392226148%\" valign=\"top\"\u003e\n \u003cp\u003e112.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.250883392226148%\" valign=\"top\"\u003e\n \u003cp\u003e137.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.250883392226148%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.205298013245034%\" valign=\"top\"\u003e\n \u003cp\u003e(hkl)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.45253863134658%\" valign=\"top\"\u003e\n \u003cp\u003e222\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.673289183222957%\" valign=\"top\"\u003e\n \u003cp\u003e400\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e331\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e422\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.205298013245034%\" valign=\"top\"\u003e\n \u003cp\u003ed (hkl)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.45253863134658%\" valign=\"top\"\u003e\n \u003cp\u003e1.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.673289183222957%\" valign=\"top\"\u003e\n \u003cp\u003e1.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e0.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.556291390728475%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eWe observe that there is a difference in peak intensity, which is due to the residual stresses existing at the welded joints and the degree of crystallinity. For the two studied samples, the identification of the lines that appear corresponds well to the \u0026alpha; phase (Al) of aluminum and the intermetallic phase \u0026eta; (Al-Zn-Mg-Cu). It can be noted that the peaks of the \u0026alpha; phase (Al) along the (111) and (200) planes are the most intense. Tables V.2 and V.3 compile the XRD characteristics for the two studied samples.\u003c/p\u003e"},{"header":"IV. DISCUSSION OF RESULTS, CONCLUSION, AND RECOMMENDATIONS","content":"\u003cp\u003eThe friction stir welding (FSW) process proves to be advantageous for the welding of aluminum alloys, and it holds a highly promising future across various application domains. Most studies aimed at improving the welding process are still conducted experimentally, necessitating further refinement of welding tools and utilization parameters. Several focal points characterizing the friction stir welding process have been emphasized and studied. Subsequently, a two-fold approach has been pursued: firstly, a study of microstructural characterization, aiming to comprehend the effect of welding parameters on the mechanical properties of the welded joint.\u003c/p\u003e\n\u003cp\u003eIn the experimental segment, the FSW joint was characterized through the investigation of mechanical properties and microstructural changes. Analyses performed on the obtained weld beads enabled the correlation of joint quality with operating parameters. To achieve this, a fabrication procedure was developed to produce defect-free joints.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIt was demonstrated that welds executed on 6 mm thick plates outperform those obtained on 10 mm plates. These results are corroborated by non-destructive inspection and evaluation methods. Through microhardness testing and macroscopic observations, microstructures within different zones of the FSW bead were correlated with hardness evolution. The hardness curve profile in the heat-affected zone (HAZ) was also explained. In fact, the temperature gradient experienced by this zone leads to the observed hardness gradient. In the center of the bead, hardness increases, eventually reaching the base metal hardness. The microhardness within the heat-affected zone for the studied alloy is lower compared to other zones (nugget zone, thermo-mechanically affected zone, and the base metal). The joint obtained using the following parameters: thickness = 6mm, N = 1250 rpm, Va = 0.6 mm/min exhibited optimized mechanical characteristics. The fracture surfaces of the tensile specimens were analyzed using a Scanning Electron Microscope. Based on various observations, a mixed fracture mode was identified: a ductile rupture zone, where SEM observations revealed the presence of dimples, and another abrupt rupture zone. The presence of cavities was noted in precipitate-rich regions across the ductile rupture zone for different combinations of welding parameters.\u003c/p\u003e\n\u003cp\u003eMicrostructure analysis demonstrated that the tool\u0026apos;s rotation speed influences recrystallization conditions. Higher rotation speeds lead to greater welding energy and significant softening of the material in the HAZ. Metallographic characterization techniques highlighted the extent, grain size, and microstructural morphology of different zones within the weld bead (nugget zone, HAZ, thermo-mechanically affected zone, and base metal).\u003c/p\u003e\n\u003cp\u003eIn light of the findings of this study, future research avenues are conceivable. From an experimental standpoint, it would be interesting to investigate the effects of other FSW process parameters, such as traverse speed and tilt angle, on the mechanical properties of welded joints, and establish a correlation between microscopic phenomena and the macroscopic response of the welded structure. Additionally, post-welding heat treatments are necessary to study the influence of these treatments on the mechanical and microstructural properties of FSW-welded joints. Furthermore, expanding the scope of studied weldability, such as employing alternative tool geometries for varying thicknesses and welding the 2017AA alloy with a dissimilar natured alloy, is proposed.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflicts of Interest\u003c/h2\u003e \u003cp\u003eThe authors declare no conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003cp\u003eContributions\u003c/p\u003e\n\u003cp\u003eT.N, \u0026nbsp;N.C., M.A., H.B., I.A., S.M., and M.H.M. conceived and designed the experiments; R.K.S., S.L., and A.G. carried out the experiments; M.H.M., R.K.S., and G.P. analyzed the experimental data and wrote the manuscript. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eThomas WM Temple-Smith P (TWI, rights transferred to Lead Sheet Association): 'Friction welding sheet material'. UK Patent Application GB 2 319 977 A\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNasution AK, Gustami H, Suprastio S, Fadillah MA, Octavia J, Saidin S (2022) Potential use of Friction Welding for Fabricating Semi-Biodegradable Bone Screws. Int J Automot Mech Eng 19:9660\u0026ndash;9667\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRhodes CG, Mahoney MW, Bingel WH (1997) Effects of friction stir welding on microstructure of 7075 aluminum. ScriptaMaterialia 36(1):69\u0026ndash;75\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHagstrom J, Sandstrom R (1998) Static and dynamic properties of joints in thin-walled aluminum extrusions, welded with different methods. Proceedings of 6th International Conference on Aluminum Alloys, Toyohashi, Japan, pp.1447\u0026ndash;1452\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHashimoto T, Nishikawa N, Tazaki S, Enomoto M (1998) Mechanical properties of joints for aluminum alloys with friction stir welding process. Proceedings of 7th International Conference on Joints in Aluminum, Cambridge, UK, 15\u0026ndash;17 April 1998\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTozaki Y, Uematsu Y, Tokaji K (2007) Effect of processing parameters on static strength of dissimilar friction stir spot welds between different aluminium alloys. Fatigue Fract Eng Mater Struct 30:143\u0026ndash;148\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZulu MC, Mashinini PM (2018) Process optimization of rotary friction welding of Ti-6Al-4V alloy rods. IOP Conf Ser Mater Sci Eng 430:012012\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRamesh AP, Subramaniyan M, Eswaran P (2019) Review on Friction Welding of Similar/Dissimilar Metals. J Phys Conf Ser 1362:012032\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGuo W, You G, Yuan G, Zhang X Microstructure and mechanical properties of dissimilar inertia friction welding of 7A04 aluminum alloy to AZ31 magnesium alloy. J. Alloys\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFratini L, Barcellona A, Buffa G, Palmeri D Proc. 1 Mech. Eng. Vol.221 Part B. J. Engineering Manufacturing\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSun Y, Voyiadjis GZ, Hu W, Shen F, Meng Q (2017) Fatigue and fretting fatigue life prediction of double-lap bolted joints using continuum damage mechanics-based approach. Int J Damage Mech 6:162\u0026ndash;188\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShanjeevi C, Arputhabalan J, Pavithran E, Raju B (2019) Prediction of Optimized Friction Welding Parameter for Joining of Dissimilar Material using Friction Welding. Mater. Today Proc. 16, 838\u0026ndash;842.Proc. 2022, 57, 687\u0026ndash;692\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePaventhan R, Lakshminarayanan PR, Balasubramanian V (2012) Optimization of Friction Welding Process Parameters for Joining Carbon Steel and Stainless Steel. J. Iron Steel Res. Int. 19, 66\u0026ndash;71. Compd. 2017, 695, 3267\u0026ndash;3277\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMimouni O, Badji R, Kouadri-David [22] A, Gassaa R, Chekroun N, Hadji M (2019) Microstructure and Mechanical Behavior of Friction-Stir-Welded 2017A-T451 Aluminum Alloy. Trans Indian Inst Met. pp. 1\u0026ndash;16\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChekroun N, Mimouni O, Badji R, Gassaa R, Hadji M (2016) January. Numerical Simulation of Temperature Distribution and Material Flow During Friction Stir Welding 2017A Aluminum Alloys, MATEC Web of Conferences 80:12002\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAtharifar H, Lin DC, Kovacevic R (2009) Numerical and Experimental Investigations on the Loads Carried by the Tool During Friction Stir Welding. J Mater Eng Perform 18(4):339\u0026ndash;350\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrasanna P, Rao BS, Rao GK (2010) Finite Element Modeling for Maximum Temperature in Friction Stir Welding and its Validation. 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J Mater Process Technol 213:477\u0026ndash;486\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCao X, Jahazi M (2011) Effect of tool rotational speed and probe length on lap joint quality of a friction stir welded magnesium alloy. Mater Des 32:1\u0026ndash;11\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNandan, Nandan R, DebRoy T, Bhadeshia H et al (2008) Recent advances in friction-stir welding-process, weldment structure and properties. Prog. Mater. Sci. 2008, 53, 980\u0026ndash;1023\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrasanna Nagasai B, Malarvizhi S, Balasubramanian V (2022) Mechanical properties and microstructural characteristics of AA5356 aluminum alloy cylindrical components made by wire arc additive manufacturing process. Mater Per Cha 11(1):1\u0026ndash;26\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003e[30] S, Raja A, Sachin Adithyaa V, Sai Yaswanth R, Saranya U, Sabarivasan (2020) Establishing an empirical relationship to predict strength of dissimilar friction welded steel joints. Paideuma J 13(7):68\u0026ndash;82\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003e[31] G, Vairamani T, Senthil kumar S, Malarvizhi V, Balasubramanian (2013) Predicting tensile strength and interface hardness of friction welded dissimilar joints of austenitic stainless steel and aluminium alloy by empirical relationships. Ind Ins Wel 46(2):67\u0026ndash;75\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVairamani G, Senthil kumar T, Malarvizhi S, Balasubramanian V (2013) Developing empirical relationships to predict tensile strength and interface hardness of friction welded Medium carbon steel - Austenitic stainless steel joints. IWS J 21\u0026ndash;27\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVairamani G, Senthilkumar T, Malarvizhi S, Balasubramanian V (2013) Application of response surface methodology to maximize tensile strength and minimize interface hardness of friction welded dissimilar joints of austenitic stainless steel and copper alloy. Tran Nonferrous Met Soc Chi 23(8):2250\u0026ndash;2259\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrasanna Nagasai B, Malarvizhi S, Balasubramanian V (2021) Mechanical properties of wire arc additive manufactured carbon steel cylindrical component made by gas metal arc welding process. J Mech Beha Mat 30:188\u0026ndash;198\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"FSW, Microstructure, Weld joint, HAZ, mechanical properties","lastPublishedDoi":"10.21203/rs.3.rs-3989261/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3989261/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe qualification of the FSW process in aerospace requires the production of high-quality joints with long tool lifespan. This necessitates fine-tuning process parameters such as tool geometry (shoulder and pin dimensions, threading) and feed and rotation speeds. The experimental part involves characterizing the FSW weld joint through the study of mechanical properties and microstructural changes. The analyses and control observations performed on the obtained weld beads have, on one hand, enabled the correlation of joint quality with operational parameters. To achieve this, a local fabrication procedure aimed at producing defect-free joints was devised. Microstructural analysis revealed that the tool's rotation speed influences recrystallization conditions; the higher the rotation speed, the greater the welding energy and the more pronounced the softening of the material in the Heat Affected Zone (HAZ).\u003c/p\u003e","manuscriptTitle":"Preparation, Inspection, and Optimization of Rotary Friction Welding Parameters for 2017aa Aluminum Alloy Specimens.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-12 09:26:17","doi":"10.21203/rs.3.rs-3989261/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revisions Needed","date":"2024-06-01T12:39:26+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-04-05T20:49:37+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-03-08T17:11:09+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-03-08T00:25:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"The International Journal of Advanced Manufacturing Technology","date":"2024-03-06T03:01:06+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"7575e84f-c824-4477-96c7-3e2757da3f90","owner":[],"postedDate":"March 12th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-07-12T18:02:11+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-12 09:26:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3989261","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3989261","identity":"rs-3989261","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}