Effect of Adding Machining Swarf of Brass Alloy on the Microstructure and Toughness of Gray Cast Iron

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The addition of 1 wt.% swarf contributed to the finer characteristics of the graphites categorized as types A and E while simultaneously increasing the quantity of pearlite grains present. When the amount of swarfs was increased to 3 and 5 wt.%, the graphite became finer due to rapid solidification, and a transitional interface of pearlite was also observed. The addition of 1 wt.% swarf to the cast iron led to an increase in hardness from 200 HB to 212 HB. However, as the swarf content increased, a reduction in hardness was observed, with the composites containing 3 wt.% and 5 wt.% swarf achieving hardness values of 197 HB and 185 HB, respectively. This phenomenon is linked to the presence of the softer brass phase in the composite structure. The microhardness of these swarfs was measured at approximately 99 Vickers, which was the minimum value. The soft phase of the swarf had a positive effect on increasing the impact energy due to ductile fracture, whereas the absence of the swarf led to brittle fracture in gray cast iron and the 1 wt.% composite. The impact energies of graycast iron and the 1 wt.%, 3 wt.% and 5 wt.% composites were measured to be 3, 4.2, 5.7, and 10.6 Joules, respectively. Physical sciences/Engineering Physical sciences/Materials science Physical sciences/Materials science/Structural materials Gray cast iron copper alloy cast iron composite fracture energy Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1- Introduction Currently, the rapid evolution of scientific advancements has created a pressing need for the development of new engineering alloys with unique characteristics. Moreover, gray cast iron, owing to its good mechanical properties, excellent wear properties, high hardness, and low production cost in heavy industries, transportation, and engineering machinery, is still the most popular and widely utilized material. Nevertheless, there is a need to enhance its engineering properties. The fundamental difference between cast iron and steel is the special structure of carbon in the matrix. In cast iron, carbon is mainly found as graphite, which is a critical factor in dictating the material's properties [ 1 ]. Silicon, as a strong graphitizing element in cast iron plays a vital role in dictating the quality and amount of graphite produced within the alloy [ 2 ] [ 3 ]. Flake graphites in gray cast irons are stress concentration sites and affect mechanical properties, especially toughness, and reduce the ductility of gray cast iron [ 4 ] [ 5 ]. The high degree of brittleness found in gray cast iron is a key limitation in its extensive use, making it the foremost negative attribute of this material. Modern methods for increasing the mechanical properties of cast iron include heat treatment, surface modification, composites, and alloying. The addition of alloying elements, due to the sensitivity of cast iron, significantly improves the mechanical properties and wear behavior. In addition to carbon and silicon, which are the most important alloying elements in cast iron [ 6 ]، [ 7 ]; however, other elements like tin (Sn) can significantly improve the pearlitic matrix and enhance wear resistance [ 8 ]. Furthermore, the incorporation of niobium (Nb) and molybdenum (Mo) effectively reduces both the length of graphite and the interlayer distance of pearlite [ 9 ] [ 10 ]. Chromium is a strong carbide-forming element that has a good effect on gray cast irons in improving wear and hardness [ 11 ] .Nickel also acts as a graphitizer and refines pearlite in cast iron [ 12 ]. Among the various alloying elements, copper has recently attracted significant interest for its important effects on the properties of cast irons. Copper can increase the formation of graphite in the eutectic transformation, but it reduces the formation of graphite in the eutectoid transformation and consequently increases the amount of pearlite [ 13 ]. Furthermore, copper is beneficial in augmenting wear resistance, corrosion resistance in acidic environments, and the mechanical properties of tensile strength and hardness [ 14 ] [ 15 ] [ 16 ]. The presence of copper facilitates an increase in graphitization, which is accompanied by a decrease in the size of the graphite [ 17 ] [ 18 ] [ 19 ]. The decrease in the size of graphite contributes positively to strength enhancement upon the addition of copper [ 20 ]. Copper as a nano-modifying additive can significantly reduce the friction coefficient of cast iron [ 21 ]. In addition, the addition of copper at a rate of 1.18 wt% has a positive effect on the elongation of gray cast iron [ 22 ].Akinyemi et al. reported an increase in the UTS of gray cast iron to 740 MPa by adding alloying elements of copper and nickel (0.5wt% Cu 5.2wt% N) [ 23 ]. Similarly, Agunsoye et al. emphasized the role of copper addition as a crucial factor in augmenting the fracture energy of gray cast iron [ 24 ]. Simultaneous addition of molybdenum and copper increases hardness and tensile strength but has a negative effect on fractur energy [ 25 ]. The combination of chromium and copper results in a significant enhancement of hardness and strength, attributed to the refinement of the pearlite structure and an increase in wear resistance [ 26 ]. Hejazi et al. considered the presence of copper wire as a factor in changing the graphite distribution from type A to a wider distribution of types E, D, and B [ 27 ]. Brass alloys are extensively utilized across various industrial applications, including bushings, bearings, and valve fittings, owing to their excellent corrosion resistance, significant ductility, and satisfactory strength[ 28 ] [ 29 ]. Machining is the most important processing operation in the production of brass parts due to the excellent machinability properties of brass alloys [ 30 ]. This leads to the production of many machining chips from this valuable alloy. The existence of key elements, including copper and zinc, within these chips provides a valuable resource for improving the mechanical characteristics of cast iron. Zinc alloys are mostly used as coatings for cast iron; however, they also demonstrate beneficial properties when applied to ferritic substrates [ 31 ]. Following the successful integration of superalloy machining swarfs into gray cast iron, which led to improvements in wear resistance and toughness [ 32 ], this research investigated the effects of adding brass alloy machining swarfs on the toughness and microstructure of hypoeutectic gray cast iron. 2- Materials and methods To begin with, swarfs generated from the continuous machining of a brass alloy were prepared, as outlined in Table 1. These swarfs were then placed into a polystyrene foam model that has a density of 20 kg/m³. The amount of swarfs in weight percentages of 0 wt.%, 1 wt.%, 3 wt.% and 5 wt.% were placed inside the foam models with dimensions of 70×70×100 mm. The chips were assessed to be longer than the foam models, which ensures that during the incineration of the foam model (Lost foam casting), the chips do not shift and are securely held in place by the molding sand on both sides. Figure 1 a shows the image of the foam model filled with machining chips. After preparing the model and the runner system, silica sand was mixed with 4 wt.% sodium silicate adhesives in a mixer for 10 minutes. The models and the runner were molded inside the mold with the silica sand and sodium silicate adhesive mixture which was subsequently toughed by the injection of CO2 gas. Table 1 gives the chemical composition of the GG20 ingot used for casting. After preparing the melt in the induction furnace, it was transferred to a preheated ladle, and after slag removal, the melt was cast at a temperature of 1280 c. Figure 1 -b shows the casting mold, which was fixed with two 30 kg cast iron weights to prevent the melt from penetrating the mold. After a complete solidification time of 24 hours at the workshop's temperature, the components were cleaned through shot blasting, and the runner system was subsequently removed with the aid of a bandsaw. Metallographic samples were delineated from the casting samples through the use of a micro cutter, and their preparation adhered to the ASTM E3 standard. For etching the samples, 2% Nital (5ml HNO3, 95–96 ml methanol or ethanol) compound was used for 4 seconds and immediately washed with water and 100% ethanol and dried under a hair dryer. Optical microscope images were obtained using HUVITZ HR3-TRF-P both before and after etching. For further analysis of the sample structure and fracture surfaces, a Field Emission Scanning Electron Microscope (FESEM) equipped with X-ray diffraction (EDS) model TESCAN: MIRA 2 made in the Czech Republic was used. The fracture energy was assessed using the ASTM E 23 standard. Five samples, each measuring 10×10×55 mm, were extracted from each specimen using a wire-cutting machine. Following surface treatment, these samples were evaluated using the Charpy impact test without the introduction of a notch. The hardness of the samples was measured using the INSTRON Universal machine on the Brinell scale and according to the ASTM E10 standard. The applied load was 187.5 kg and the application time was 40 seconds. The microhardness of the Wicker was also measured using the Micro Hardness Shaab M5 model machine with an applied load of 100 g and a time of 20 seconds. Table-1 Chemical composition of gray cast iron and brass alloy. element Fe C Si Mn Ni P Al Sn Pb Zn Cu GCI 94.2 3.1 2 0.1 0.04 0.03 - 0.01 - - 0.05 brass 0.1 - 0.002 0.002 0. 05 0.002 0.5 0.09 0.1 28 69.9 Formula 1, which is the formula for calculating equivalent carbon, was used to analyze the chemical composition of cast iron [ 33 ]. $$\:CE=\:\%C+0.28\:\:\%Si+0.007\:\:\%Mn+0.092\:\:\%Cu+0.303\:\:\%P\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:(1$$ 3- Results and discussion Based on Formula 1, cast iron exhibits a carbon equivalent of 3.8, classifying it as hypoeutectic cast iron. Type A graphites have appeared in the microstructure due to equilibrium solidification, which can be seen in the OM picture in Fig. 2 -a. The matrix of the cast iron sample after etching shows a pearlitic matrix with a small amount of ferrite. This matrix is ​​very desirable for having good strength in cast iron. By adding 1 wt.% of swarf, this additive dissolves completely in the matrix, and E-type graphites are observed alongside A-type graphites. Figure 2 -b shows an optical microscope image of this sample. The incorporation of brass swarf into the matrix has led to the development of a finer pearlite matrix, with a considerable amount of fine ferrite also observable in the structure. The presence of Zn in the composition of the brass is an important factor in increasing the amount of ferrite in the matrix. In the sample with 3 wt.% composites (Fig. 3 -a), the presence of machining chips in the matrix is ​​observed, which are distributed as dots inside the matrix. The incomplete dissolution of these chips has significantly influenced the distribution of graphite, and thinner graphite layers are observed near the chips, resulting in a fundamentally altered distribution of the graphites throughout the sample. Type A, B, and D graphites with different classes (5 and 6) are seen - according to the ASTM A48 standard. In the sample with 5 wt.%, the amount of non-dissolved chips in the matrix has increased. Close to the interface of the matrix and the swarf, there is a considerable presence of type C graphite, while as one moves further from the swarf, whereas at a distance from the swarf, its distribution resembles that of the composite sample containing 3 wt.%. By etching the 3 wt.% sample in Fig. 3 , a circular ferrite region is formed near the swarf, which is distinct from the matrix. Observations indicate that swarf is found adjacent to the same ferritic region. Moreover, the mold matrix represented in this image features a pearlite-ferrite matrix. In the etched sample of 5 wt.%, Fig. 3 -b, the amount of pearlite is higher near the swarf, which indicates the presence of the pearlite-reinforcing element, namely copper. At a distance further from the swarf, the amount of ferrite is higher than in the control sample. It can be concluded that the matrix develops through two distinct mechanisms: pearlite formation adjacent to the interface and a ferrite-pearlite mixture in regions further from the interface. Figure 3 -b illustrates the melting of the chip throughout the casting process, followed by its solidification within the pearlite matrix, which lacked sufficient time for complete dissolution. The interesting point in the image is the diffusion of graphite towards the brass swarfs, this penetration has reached the interior of the swarfs to some extent. Pearlite is a eutectoid product that is composed of layers of ferrite and cementite, like a fingerprint. The dissolution of copper in the cast iron matrix facilitates the eutectoid transformation, resulting in an increase in the amount of pearlite near the interface where the diffusion rate is highest. Alongside elemental diffusion, a thermodynamic aspect is also present: the existence of swarfs contributes to the formation of new solidification fronts. This elevated cooling rate diminishes the spacing between the layers of pearlite. Both the cementite and ferrite layers are white, but corrosion caused by 2% Nital leads to grain boundary corrosion, and the grain boundaries appear as dark lines. This layer gap is an important factor in the formation of pearlite. When the gap is minimized, the carbon element can diffuse more readily, which promotes the transformation of pearlite. The rate of pearlite formation is controlled by the diffusion of carbon to form a low-carbon ferrite layer and a high-carbon cementite layer, where the presence of brass swarf acts as a feed and shifts the temperature of pearlite formation by heat transfer. In Fig. 4 a, the electron microscope images illustrate the distribution of type A graphite in the GCI matrix. When juxtaposed with Fig. 4 b, which reveals the microstructure of the 1 wt.% Swarf composite, it becomes apparent that the graphite structures are finer in the latter. Figure 4 -c presents a sample with a composition of 3 wt.% swarf. This image reveals the interface between the brass swarf and the cast iron matrix. The composite sample shown in Fig. 4 -d contains 5 wt.% of swarf. This image provides a clear representation of the structural differences observed in the various regions of the cast iron. In the upper part of the swarf, the E and D type distribution is dominant, while near the swarf, the A distribution is more visible. The shape of the swarf in Fig. 4 -d is seen as a curve. It is very likely that a significant portion of the swarf melted during casting under high temperatures and created this existing shape. The temperature at which brass melts is between 910°C and 940°C, and at elevated temperatures of 1300°C, the risk of zinc vapor formation becomes markedly high [ 34 ]. In the two images of Fig. 4 c and d, two lines are drawn from the matrix region to the swarf region. Figure 5 shows the distribution of elements along these lines. As illustrated in Fig. 5 a, the diffusion of zinc and copper elements in the cast iron matrix starts at a distance of 18 µm and continues to a significant extent up to 22 µm. After that, the diffusion rate inside the cast iron matrix decreases, indicating that the diffusion time during the melting and solidification processes was sufficiently appropriate. As illustrated in Fig. 5 -b, the diffusion rate was notably absent, recorded at around 5 µm. This can be explained by the considerable amount of brass swarf incorporated into the melt, which acted as a chill and led to the formation of new solidification fronts at these lower temperature zones. This rapid solidification, due to the drop in temperature and the strong dependence of diffusion on temperature, significantly reduced the diffusion rate. In both linear distributions of elements within the cast iron matrix, the amount of carbon element sometimes increases greatly, which is fundamentally linked to the presence of the pure graphite phase. The comparison of the two lines within the cast iron matrix demonstrates that the diffusion rates of copper and zinc in the 3 wt. % sample are more effective at longer distances than in the 5 wt.% composites. One important factor for the low diffusion of zinc and nickel elements is the high cooling rate in the 5 wt.% composites. Cooling rates play a crucial role in determining how quickly the elements diffuse. On the other hand, the increased quantity of swarf has facilitated the development of localized zones rich in alloying elements. This situation has led to a reduction rate of diffusion in the sample, primarily due to the occurrence of supersaturation. The map image presented in Fig. 6 details the elemental distribution in the 5wt.% composite sample. Analysis of the image indicates that carbon has not diffused into the brass, and its presence is noted at several specific points. However, the extent of silicon diffusion observed in the swarf is minimal. In addition, there are two points in the image where the silicon concentration is at its highest, indicated by a deep blue color in the swarf. Iron, like carbon, is only found in the cast iron matrix. In this image, copper has the highest diffusion and has moved from the swarf side to the cast iron. The swarf interface has the highest copper content compared to the matrix further away, which can be better understood from Fig. 3 -b. Near the swarf, the distinct pearlitic zone, marked by the small size of the pearlitic grains and the close arrangement of the pearlitic layers, reveals the same copper trace that is clearly depicted in this image. Zinc elements, which are heavier than other elements, behave in a similar way to copper, but the diffusion rate of this element is low compared to copper, and its maximum amount is seen in the swarf. However, zinc has a significant diffusion rate compared to other elements. The behavior of alloying elements varies significantly in the presence of a concentration gradient. The diffusion of these elements is inversely proportional to their melting points; thus, elements with lower melting points are associated with higher diffusion coefficients. In the presented image, the diffusion of the two elements zinc and copper was also indicative of this issue. Alongside diffusion, an additional vital process contributes to the dissolution of elements embedded in the matrix. Such as local melting and convection created inside the melt due to the contact of two dissimilar melts. The movement of molten brass and cast iron occurs as a result of the concentration gradient and variations in density, allowing the two melts to interpenetrate through convective processes. This action creates several brass spots inside the cast iron, which creates a larger contact surface for these melts, facilitating diffusion and dissolution. This convection can also cause some casting defects. These casting defects undoubtedly require both substantial and rapid convection. However, the closely matched densities of the two materials hinder this process, resulting in a slower movement of the melts together. The bar graph presented in Fig. 7 illustrates the variations in hardness resulting from the incorporation of the swarf. The addition of 1wt.% of swarf resulted in a hardness increase from 200HB to 212HB. Copper is important factor in reducing the gap of the pearlite layers (ferrite and cementite), which is the same factor that enhances the hardness in samples containing 1wt.% brass [ 35 ]. In samples with 3wt.% swarf, the hardness is slightly lower than the GCI sample and 197HB, in samples containing 5wt.% swarf, the hardness measures a mere 185HB. This phenomenon is primarily due to the presence of a soft brass phase embedded in the cast iron matrix. Moreover, the D-type graphites incorporated into the 5wt.% composite matrix further reduce the chances of pearlite formation in comparison to other samples. The presence of ferrite is also another reason for reducing hardness due to the softness of this structure. The influence of the pearlitization of copper is recognized as a means of increasing hardness; however, during deformation under load, the existence of soft zones within the cast iron matrix greatly reduces hardness. The presence of these soft zones complicates the behavior of the 5wt.% composite. The Brinell ball serves as an excellent tool for evaluating the hardness of materials characterized by various phases. When force is exerted, it not only impacts the material being tested but also influences the neighboring surfaces and their phases. Furthermore, the presence of the soft zone suggests plastic behavior and leads to an increase in the area of ​​impact and ball depression. The microhardness graph depicted in Fig. 8 , corresponding to the sample with 5wt.%, is provided to facilitate a deeper understanding of the hardness behavior and its alterations in distinct areas of the sample structure. This graph starts from the cast iron matrix and enters the brass region by passing through the interface. Analyzing the graph closely indicates that the microhardness adjacent to the interface is elevated compared to the matrix situated further away. In particular, the maximum microhardness in the cast iron matrix is ​​near the interface. The process of diffusion of the pearlite reinforcing element into the matrix near the interface results in an increased presence of pearlite in that specific region. In contrast, the diffusion of copper in the more distant regions of the matrix is reduced, leading to a decrease in pearlite content, which subsequently enhances the hardness in the areas close to the interface. As the graph enters the brass region, the microhardness decreases significantly and reaches 109 Vickers. In the inner parts of the brass chip, this number becomes even lower and reaches 99 HV. This observation illustrates the non-uniform distribution of hardness throughout the composite sample. The graph in Fig. 9 shows the changes in the impact energy of the samples with increasing amounts of brass swarf. The GCI sample demonstrates an impact energy of 3J, a notably low figure. This low value can be attributed to the presence of flaky graphite within the gray cast iron matrix, identified as a site of stress concentration. Consequently, the control sample exhibits brittle characteristics. By adding 1wt.% brass swarf, the impact energy increases by 40% and reaches 4.2J. One of the factors in increasing the impact energy is the finer grain size of the pearlite matrix. The enhancement of pearlite grain quantity plays a crucial role in augmenting impact energy [ 36 ]. In addition, finer graphite was also an important factor in this. In the composite samples with a concentration of 3wt.%, there was a significant increase in impact energy, which peaked at 5.7J. Conversely, the samples with a concentration of 5wt.% exhibited the highest impact energy, attaining a value of 10.6J. Increasing the impact energy level, in addition to the structure of the cast iron matrix (fine pearlites and fine graphites), has another very important parameter, which is the presence of an undissolved swarf in the cast iron matrix. These swarfs are a major obstacle during crack growth. Figure 10 shows scanning electron microscopy (SEM) images of the fractured samples resulting from the impact test. Images labeled a and b depict the fracture surfaces of the GCI samples and the 1wt.% swarf composite sample, respectively. Deep dimples in the images indicate a weak interface between the matrix and graphite and indicate a brittle fracture of the samples. Although this test was performed without creating notches in the fractured samples, the presence of flake dendritic graphite acts like a crack. The tips of these flake graphite act as stress concentration points, highlighting the fact that the graphites themselves are vulnerable areas [ 37 ]. In Fig. 10 c, the fracture surface of the sample with 3wt.% of swarf is observed. A distinct and heterogeneous region, marked by a cast iron matrix, is visible in the middle of the image. This area has developed due to the presence of a brass swarf, which was not adequately eliminated during the melting process. The central area of Fig. 10 -d illustrates the region influenced by the swarf. The images depict the varying behaviors of the phases present within the swarf as crack growth occurs, and these behaviors are considered to be key factors in the rise of impact energy. The crack exhibits a crucial shift in its direction as it expands in interaction with the swarf, which itself undergoes a morphological change, and this change is observed at the interface and center of the sample. The presence of a substantial depression and bulge signifies a modification in the fracture direction during the progression of crack growth. In fact, this phenomenon stops the growth of the crack, and when the crack enters the brass zone, the deep depressions and peaks become less pronounced, and replaced by more gradual depressions and peaks, along with the formation of microvoids. In Fig. 10 -d, the same issue is repeated, but the amount of swarf in this image is higher and in addition, the interface between the matrix fracture surface and the swarf has formed a larger ring. The interface region in the 3 and 5 wt.% samples exhibit a more distinct contrast from both the matrix and the swarf. In addition to the presence of a swarf, the cast iron area around the swarf has slightly finer dimples compared to the GCI matrix. This could be due to the fine grain size created by the high cooling rate caused by the presence of a brass swarf. The interface observations in the image confirm that the deep dimples resulting from the weak interface of graphite with the iron matrix have been replaced by finer microvoids and depressions. Although the amount of swarf in the image is low, the effect of this parameter is much higher in the fractured image. The analysis of the GCI and 1wt.% composite samples indicates a consistent brittle fracture mechanism. In contrast, the samples containing swarf at 3 and 5wt.% show more complex behavior and mechanism due to the presence of swarf in the matrix. Upon hammer impact, the crack within the cast iron matrix propagated in a brittle manner, altering its path when it encountered the interface. In the brass swarf region, the fracture behavior transitioned to a softer, more ductile mode. Indeed, the mechanism of fracture involves both ductile and brittle characteristics. Furthermore, the brass swarf layer serves as a shock-absorbing medium during impacts, thereby mitigating the initial effects of such impacts. 4- Conclusion The present research focuses on the effects of adding brass alloy machining swarf to hypoeutectic gray cast iron, and the significant findings are summarized as follows: The addition of 1wt.% brass swarf modified the graphite distribution, shifting it from type A to types E and A, while also resulting in a finer graphite and an enhanced quantity of fine pearlite grains. Increasing the amount of swarf to 3 and 5wt.%, in addition, to type A, E graphites, type D, and C graphites also increased the amount of pearlite grains due to the presence of undissolved swarf in the field due to the penetration of the copper element and also the high solidification rate. By analyzing the distribution line and map, researchers observed a substantial diffusion of copper in the matrix located near the swarf. Zinc element was also observed in abundance in areas near the swarf. By adding 1wt.% of swarf to cast iron, the hardness changed from 200HB to 212HB, which was influenced by factors such as fine grain size and pearlitic matrix. By increasing the swarf content to 3 and 5 wt.%, the hardness decreased to 197HB and 185HB, respectively. Analysis of the microhardness graph illustrated the hardness of the cast iron matrix located near the maximum swarf. This region exhibited a pronounced pearlitic structure, significantly influenced by the presence of nickel. In contrast, The hardness in the swarf was minimal and the hardness of the swarf was measured to be 99 HV. The impact energy of the swarf increased by 40% with the addition of 1wt.% swarf and reached 4.2 Joules. Increasing the amount of swarf to 3 and 5 wt.% by weight, this value increased to 5.7J and 10.2J, which was very high compared to the control sample. The analysis of the fracture mechanism revealed that the gray cast iron exhibited brittleness attributed to the presence of flake graphite. Conversely, samples with 5 and 3wt.% of swarf exhibited cracks that initiated and propagated within the cast iron matrix. The interface between the swarf and the matrix presented a challenge to the propagation of these cracks. After the crack direction was altered at this interface, the brass soft zone revealed a ductile fracture characteristic. This led to the creation of a complex fracture mechanism and a mixture of brittle and ductile fracture in the composite samples with 3 and 5 wt.% by weight of the swarf. Declarations Competing interests: The authors have no relevant financial or non-financial interests to disclose. The authors have no competing interests to declare that are relevant to the content of this article. All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. The authors have no financial or proprietary interests in any material discussed in this article. funding statement: The authors did not receive support from any organization for the submitted work. No funding was received to assist with the preparation of this manuscript. No funding was received for conducting this study. No funds, grants, or other support was received. data availability statement : The data is available on reasonable request from the corresponding author. Author Contribution Mahdi Ranjbar: Draft writer, executive activitiesZahra Sadat Seyed Raoofi: Supervisor - ReviewSeyed Hossein Razavi: Consultant - ReviewYazdan Shajari: Consultant - Methodologist - ReviewAhad Nasimi: Executive activities - Characterization testsMilad Shadi: Executive activities - Casting repetition - Sample preparation References Zhang, S., Ran, Y., Murphy, A., Zhang, G. & Wang, W. Residual stress analysis of gray cast iron manufacturing processes. Mater. Manuf. Processes 35 , 15. 1781–1788. https://doi.org/10.1080/10426914.2020.1802035 ;(2020). Sudiyanto, A., Kartikasari, R., Setiawan, A. & Sufi Rizki Lillah. and. The effect of silicon content on microstructure and mechanical properties of gray cast iron. In AIP Conference Proceedings, 2598. 1; (2023). https://doi.org/10.1063/5.0130605 Singhal, P. & Saxena, K. K. Effect of silicon addition on microstructure and mechanical properties of grey cast Iron: An overview. Mater. 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Sci. Heat. Treat. 45 , 7: 254–258. https://doi.org/10.1023/A:1027320116132 (2003). Abdou, S., Elkaseer, A., Kouta, H. & Jaber Abu Qudeiri. Wear behaviour of grey cast iron with the presence of copper addition. Adv. Mech. Eng. 10 . 101687814018804741. https://doi.org/10.1177/1687814018804741 (2018). Mishra, H., Shekhar, R., Sahu & Padan, D. S. Effect of copper as an alloying element on microstructure and mechanical properties of grey cast iron. Trans. Indian Inst. Met. 76 , 7: 1875–1883. https://doi.org/10.1007/s12666-023-02894-5 (2023). Kutelu, B. J., Ogundeji, O. O. & Oluyori, R. T. Microstructure Characteristic and Mechanical Properties of Copper Influenced Grey Cast Iron. Saudi J. Civ. Eng. 8 , 5.65–75. 10.36348/sjce.2024.v08i05.001 (2024). Drozdov, V. O., Cherepanov, A. N., Filippov, A. A. & Shevtsova, L. I. Nanomodification of the properties of gray cast iron alloyed with copper. AIP Conf. 2504. https://doi.org/10.1063/5.0133100 (2023). Kutelu, B., Johnson, Oke Olugbenga, O. G. U. N. D. E. J. I. & Francis Oladapo. Microstructure Characteristics, Mechanical and Corrosion Properties of Copper Alloyed Hypo-Eutectic Grey Cast Iron. Saudi J. Civ. Eng. 7 , 10: 252–259. 10.36348/sjce.2023.v07i10.002 (2023). Akinyemi, O. O., Adeboje, T. B. & Aremu, A. A. Composite Effect of Nickel and Copper on the Characteristics of Grey Cast Iron. InProceedings of Canadian-American Conference for Academic Disciplines. 4, 357–362; (2015). Agunsoye, J. O., Bello, S. A., Hassan, S. B. & Adeyemo, R. G. Odii. The effect of copper addition on the mechanical and wear properties of grey cast iron. JMMCE 2 (470), 05. 10.4236/jmmce.2014.25048 (2014). Upadhyay, S., Kuldeep, K. & Saxena Effect of Cu and Mo addition on mechanical properties and microstructure of grey cast iron: An overview. Mater. Today Proc. 26. 2462–2470; (2020). https://doi.org/10.1016/j.matpr.2020.02.524 Habireche, M. et al. Effect of copper and chromium addition on the mechanical and wear resistance of tempered hypoeutectic grey cast iron used in crusher application. Int. J. Metalcast. 16 (4), 1869–1884. https://doi.org/10.1007/s40962-021-00727-z (2022). Hejazi, M., Mehdi, M., Divandari & Taghaddos, E. Effect of copper insert on the microstructure of gray iron produced via lost foam casting. Mater. Des. 30 , 4: 1085–1092. https://doi.org/10.1016/j.matdes.2008.06.032 (2009). Afshar, F. J. & Gholam Reza Khayati. The application of superhydrophobic coatings to brass alloy substrates: A review. J. Alloys Compd. 960 , 170634. https://doi.org/10.1016/j.jallcom.2023.170634 (2023). Moussa, M. E., Amin, M. & Khaled, M. Ibrahim. Effect of ultrasonic vibration treatment on microstructure, tensile properties, hardness and wear behaviour of brass alloy. Int. J. Metalcast. 17 , 1: 305–313. https://doi.org/10.1007/s40962-021-00748-8 (2023). Semih, Ö. & Recep, A. Investigation of microstructure, machinability, and mechanical properties of new-generation hybrid lead-free brass alloys. High. Temp. Mater. Processes . 42 , 1: 20220263. https://doi.org/10.1515/htmp-2022-0263 (2023). Yoneda, H. & Asano, K. Effects of zinc on the microstructure and mechanical properties of cast iron. Foundryman 96 , 10 247–249 (2003). Mehdi Ranjbar, S. H., Razavi, Z. S., Seyedraoufi, Y. & Shajari Investigating the effect of optimal addition of Inconel 718 machining swarfs on the wear behavior of gray cast iron,Journal of Materials Research and Technology, ISSN 2238–7854, (2025). https://doi.org/10.1016/j.jmrt.2025.01.199 de La Torre, U., Lacaze, J. & Sertucha, J. Chunky graphite formation in ductile cast irons: effect of silicon, carbon and rare earths. Int. J. Mater. Res. 10 (11), 1041–1050. https://doi.org/10.3139/146.111434 (2016). Li, C., Liu, Y. & Liu, J. Effect of process parameters on surface quality and bonding quality of brass cladding copper stranded wire prepared by continuous pouring process for clad. J. Mater. Res. Technol. 26 , 8. https://doi.org/10.1016/j.jmrt.2023.09.140 (2023). Razumakov, A. A., Stepanova, N. V., Bataev, I. A., Lenivtseva, O. G. & Riapolova, I. I. Emurlaev. The structure and properties of cast iron alloyed with copper. IOP Conf. Ser. : Mater. Sci. Eng. 124 . 1 , 01213. 10.1088/1757-899X/124/1/012136 (2016). Collini, L., Nicoletto, G. & Konečná, R. J. M. S. Microstructure and mechanical properties of pearlitic gray cast iron. Mater. Sci. Eng. A . 488 (1–2), 529–539. https://doi.org/10.1016/j.msea.2007.11.070 (2008). Z. G. S. A. Ş. P. Ş. H. A. a. E. T. Taşliçukur, Characterization of microstructure and fracture behavior of GG20 and GG25 cast iron materials used in valves. In Proceedings of the 21st International Conference on Metallurgy and Materials, Brno, Czech Republic,. 23–25. (2012). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 20 Feb, 2026 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 20 Mar, 2025 Reviews received at journal 09 Mar, 2025 Reviews received at journal 25 Feb, 2025 Reviewers agreed at journal 17 Feb, 2025 Reviewers agreed at journal 17 Feb, 2025 Reviewers invited by journal 17 Feb, 2025 Editor assigned by journal 17 Feb, 2025 Editor invited by journal 13 Feb, 2025 Submission checks completed at journal 11 Feb, 2025 First submitted to journal 08 Feb, 2025 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. 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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-5988603","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":414204995,"identity":"e7350186-1e18-4efa-8dbb-a43341c568ae","order_by":0,"name":"Mehdi Ranjbar","email":"","orcid":"","institution":"Iran University of Science and Technology (IUST)","correspondingAuthor":false,"prefix":"","firstName":"Mehdi","middleName":"","lastName":"Ranjbar","suffix":""},{"id":414204996,"identity":"f3d0fae6-6772-4acb-9b2e-95baa0fa5583","order_by":1,"name":"Zahra-Sadat 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(IUST)","correspondingAuthor":false,"prefix":"","firstName":"Seyed","middleName":"Hossein","lastName":"Razavi","suffix":""},{"id":414204998,"identity":"6e362234-f0f2-4666-8e34-006aaa87f6c5","order_by":3,"name":"Yazdan Shajari","email":"","orcid":"","institution":"Materials and Energy Research Center","correspondingAuthor":false,"prefix":"","firstName":"Yazdan","middleName":"","lastName":"Shajari","suffix":""},{"id":414204999,"identity":"4f4ac7c6-38f7-4e83-a692-8a0401f0d83b","order_by":4,"name":"Ahad Nasimi","email":"","orcid":"","institution":"Iran University of Science and Technology (IUST)","correspondingAuthor":false,"prefix":"","firstName":"Ahad","middleName":"","lastName":"Nasimi","suffix":""},{"id":414205000,"identity":"4e6b407b-e543-492d-9fe7-518777b45292","order_by":5,"name":"Milad Shadi","email":"","orcid":"","institution":"Iran University of Science and Technology (IUST)","correspondingAuthor":false,"prefix":"","firstName":"Milad","middleName":"","lastName":"Shadi","suffix":""}],"badges":[],"createdAt":"2025-02-08 15:23:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5988603/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5988603/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-026-40916-6","type":"published","date":"2026-02-20T15:57:50+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":76204664,"identity":"357b4aa7-d12b-40a0-ba22-d0b99ae6d640","added_by":"auto","created_at":"2025-02-13 12:22:55","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":657140,"visible":true,"origin":"","legend":"\u003cp\u003ea) Schematic of four foam models with a runner system. b) Mold filled with melt.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/26f39609972da569da2fa93e.png"},{"id":76204668,"identity":"68ad052c-0988-4e16-bef0-ae2a88b63ea1","added_by":"auto","created_at":"2025-02-13 12:22:55","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1589581,"visible":true,"origin":"","legend":"\u003cp\u003ea) OM images of a cast iron sample b) OM images of a composite sample with 1 wt.%\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/1b6a823eb93700659d684abe.png"},{"id":76206934,"identity":"58cbbb7e-7f57-42b7-998b-70204a22cbf4","added_by":"auto","created_at":"2025-02-13 12:46:55","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1259236,"visible":true,"origin":"","legend":"\u003cp\u003ea) OM images of composite sample 3 wt.% b) OM images of composite sample 5 wt.%\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/26a69bf9687258fcde421b6b.png"},{"id":76205646,"identity":"8104ffd9-3a9a-417b-b23d-41a6ebaf24a4","added_by":"auto","created_at":"2025-02-13 12:30:55","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1169369,"visible":true,"origin":"","legend":"\u003cp\u003eBSE images of the matrix a) GCI sample b) Composite sample with 1 wt.% swarf, c) Composite sample with 3 wt.% swarf, and d) Composite sample with 5 wt.% swarf.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/8c3a4a76ec639332d8ba616e.png"},{"id":76204672,"identity":"cba3e143-cf43-417b-b4fb-439f21ad1539","added_by":"auto","created_at":"2025-02-13 12:22:55","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":179475,"visible":true,"origin":"","legend":"\u003cp\u003eElement distribution line a) Mark 1 b) Mark 2\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/f04217b5917de4a7c500812f.png"},{"id":76205649,"identity":"cef10a97-06f4-49da-b939-add18969168d","added_by":"auto","created_at":"2025-02-13 12:30:55","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1061260,"visible":true,"origin":"","legend":"\u003cp\u003eElemental distribution map of the composite consisting of 5 wt.% composite.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/38135b05ce042356729492eb.png"},{"id":76205648,"identity":"ccbf415a-bd19-4e13-a9d4-5b0ff68f52b3","added_by":"auto","created_at":"2025-02-13 12:30:55","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":21684,"visible":true,"origin":"","legend":"\u003cp\u003eBar chart of Brinell hardness of the samples.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/7fc9df818745a2358920eb90.png"},{"id":76204673,"identity":"dbfb2610-e73b-497e-a261-1470adc35f2b","added_by":"auto","created_at":"2025-02-13 12:22:55","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":29607,"visible":true,"origin":"","legend":"\u003cp\u003eLinear microhardness diagram of a sample containing 5wt.% of swarf.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/0a0388af9c763bdf19363e56.png"},{"id":76204675,"identity":"bd8a5355-cc5b-4926-974b-1ffcf7525a5f","added_by":"auto","created_at":"2025-02-13 12:22:55","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":18966,"visible":true,"origin":"","legend":"\u003cp\u003eBar chart of fracture energy of samples.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/c4bcab7cc0eb615e1d13f7a0.png"},{"id":76205654,"identity":"6e9b5c72-43c7-468c-b22a-a5c6c40ee329","added_by":"auto","created_at":"2025-02-13 12:30:55","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":1340783,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of fracture surfaces of samples a) GCI sample b) Composite with 1 wt.% swarf c) Composite with 3 wt.% swarf d) Composite with 5 wt.% swarf\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/2bae82a2698e64f31bf4c961.png"},{"id":103251396,"identity":"b765439e-185a-41fc-862a-11a36d505e13","added_by":"auto","created_at":"2026-02-23 16:08:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8144147,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5988603/v1/cc7ebc75-9ce7-47a0-b44e-38c4c08e93de.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of Adding Machining Swarf of Brass Alloy on the Microstructure and Toughness of Gray Cast Iron","fulltext":[{"header":"1- Introduction","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eCurrently, the rapid evolution of scientific advancements has created a pressing need for the development of new engineering alloys with unique characteristics. Moreover, gray cast iron, owing to its good mechanical properties, excellent wear properties, high hardness, and low production cost in heavy industries, transportation, and engineering machinery, is still the most popular and widely utilized material. Nevertheless, there is a need to enhance its engineering properties.\u003c/p\u003e \u003cp\u003eThe fundamental difference between cast iron and steel is the special structure of carbon in the matrix. In cast iron, carbon is mainly found as graphite, which is a critical factor in dictating the material's properties [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Silicon, as a strong graphitizing element in cast iron plays a vital role in dictating the quality and amount of graphite produced within the alloy [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Flake graphites in gray cast irons are stress concentration sites and affect mechanical properties, especially toughness, and reduce the ductility of gray cast iron [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The high degree of brittleness found in gray cast iron is a key limitation in its extensive use, making it the foremost negative attribute of this material. Modern methods for increasing the mechanical properties of cast iron include heat treatment, surface modification, composites, and alloying. The addition of alloying elements, due to the sensitivity of cast iron, significantly improves the mechanical properties and wear behavior. In addition to carbon and silicon, which are the most important alloying elements in cast iron [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]، [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]; however, other elements like tin (Sn) can significantly improve the pearlitic matrix and enhance wear resistance [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Furthermore, the incorporation of niobium (Nb) and molybdenum (Mo) effectively reduces both the length of graphite and the interlayer distance of pearlite [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Chromium is a strong carbide-forming element that has a good effect on gray cast irons in improving wear and hardness [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] .Nickel also acts as a graphitizer and refines pearlite in cast iron [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAmong the various alloying elements, copper has recently attracted significant interest for its important effects on the properties of cast irons. Copper can increase the formation of graphite in the eutectic transformation, but it reduces the formation of graphite in the eutectoid transformation and consequently increases the amount of pearlite [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Furthermore, copper is beneficial in augmenting wear resistance, corrosion resistance in acidic environments, and the mechanical properties of tensile strength and hardness [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The presence of copper facilitates an increase in graphitization, which is accompanied by a decrease in the size of the graphite [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The decrease in the size of graphite contributes positively to strength enhancement upon the addition of copper [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Copper as a nano-modifying additive can significantly reduce the friction coefficient of cast iron [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In addition, the addition of copper at a rate of 1.18 wt% has a positive effect on the elongation of gray cast iron [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].Akinyemi et al. reported an increase in the UTS of gray cast iron to 740 MPa by adding alloying elements of copper and nickel (0.5wt% Cu 5.2wt% N) [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Similarly, Agunsoye et al. emphasized the role of copper addition as a crucial factor in augmenting the fracture energy of gray cast iron [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Simultaneous addition of molybdenum and copper increases hardness and tensile strength but has a negative effect on fractur energy [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The combination of chromium and copper results in a significant enhancement of hardness and strength, attributed to the refinement of the pearlite structure and an increase in wear resistance [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Hejazi et al. considered the presence of copper wire as a factor in changing the graphite distribution from type A to a wider distribution of types E, D, and B [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBrass alloys are extensively utilized across various industrial applications, including bushings, bearings, and valve fittings, owing to their excellent corrosion resistance, significant ductility, and satisfactory strength[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Machining is the most important processing operation in the production of brass parts due to the excellent machinability properties of brass alloys [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. This leads to the production of many machining chips from this valuable alloy. The existence of key elements, including copper and zinc, within these chips provides a valuable resource for improving the mechanical characteristics of cast iron. Zinc alloys are mostly used as coatings for cast iron; however, they also demonstrate beneficial properties when applied to ferritic substrates [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Following the successful integration of superalloy machining swarfs into gray cast iron, which led to improvements in wear resistance and toughness [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], this research investigated the effects of adding brass alloy machining swarfs on the toughness and microstructure of hypoeutectic gray cast iron.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"2- Materials and methods","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eTo begin with, swarfs generated from the continuous machining of a brass alloy were prepared, as outlined in Table\u0026nbsp;1. These swarfs were then placed into a polystyrene foam model that has a density of 20 kg/m\u0026sup3;. The amount of swarfs in weight percentages of 0 wt.%, 1 wt.%, 3 wt.% and 5 wt.% were placed inside the foam models with dimensions of 70\u0026times;70\u0026times;100 mm. The chips were assessed to be longer than the foam models, which ensures that during the incineration of the foam model (Lost foam casting), the chips do not shift and are securely held in place by the molding sand on both sides. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea shows the image of the foam model filled with machining chips. After preparing the model and the runner system, silica sand was mixed with 4 wt.% sodium silicate adhesives in a mixer for 10 minutes. The models and the runner were molded inside the mold with the silica sand and sodium silicate adhesive mixture which was subsequently toughed by the injection of CO2 gas. Table\u0026nbsp;1 gives the chemical composition of the GG20 ingot used for casting. After preparing the melt in the induction furnace, it was transferred to a preheated ladle, and after slag removal, the melt was cast at a temperature of 1280 c. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e-b shows the casting mold, which was fixed with two 30 kg cast iron weights to prevent the melt from penetrating the mold. After a complete solidification time of 24 hours at the workshop's temperature, the components were cleaned through shot blasting, and the runner system was subsequently removed with the aid of a bandsaw.\u003c/p\u003e \u003cp\u003eMetallographic samples were delineated from the casting samples through the use of a micro cutter, and their preparation adhered to the ASTM E3 standard. For etching the samples, 2% Nital (5ml HNO3, 95\u0026ndash;96 ml methanol or ethanol) compound was used for 4 seconds and immediately washed with water and 100% ethanol and dried under a hair dryer. Optical microscope images were obtained using HUVITZ HR3-TRF-P both before and after etching. For further analysis of the sample structure and fracture surfaces, a Field Emission Scanning Electron Microscope (FESEM) equipped with X-ray diffraction (EDS) model TESCAN: MIRA 2 made in the Czech Republic was used.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe fracture energy was assessed using the ASTM E 23 standard. Five samples, each measuring 10\u0026times;10\u0026times;55 mm, were extracted from each specimen using a wire-cutting machine. Following surface treatment, these samples were evaluated using the Charpy impact test without the introduction of a notch. The hardness of the samples was measured using the INSTRON Universal machine on the Brinell scale and according to the ASTM E10 standard. The applied load was 187.5 kg and the application time was 40 seconds. The microhardness of the Wicker was also measured using the Micro Hardness Shaab M5 model machine with an applied load of 100 g and a time of 20 seconds.\u003c/p\u003e \u003cp\u003eTable-1 Chemical composition of gray cast iron and brass alloy.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"12\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eelement\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFe\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSi\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMn\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNi\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eAl\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eSn\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eZn\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGCI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e94.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ebrass\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0. 05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e69.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFormula 1, which is the formula for calculating equivalent carbon, was used to analyze the chemical composition of cast iron [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:CE=\\:\\%C+0.28\\:\\:\\%Si+0.007\\:\\:\\%Mn+0.092\\:\\:\\%Cu+0.303\\:\\:\\%P\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:(1$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"3- Results and discussion","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eBased on Formula 1, cast iron exhibits a carbon equivalent of 3.8, classifying it as hypoeutectic cast iron. Type A graphites have appeared in the microstructure due to equilibrium solidification, which can be seen in the OM picture in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e-a. The matrix of the cast iron sample after etching shows a pearlitic matrix with a small amount of ferrite. This matrix is ​​very desirable for having good strength in cast iron. By adding 1 wt.% of swarf, this additive dissolves completely in the matrix, and E-type graphites are observed alongside A-type graphites. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e-b shows an optical microscope image of this sample. The incorporation of brass swarf into the matrix has led to the development of a finer pearlite matrix, with a considerable amount of fine ferrite also observable in the structure. The presence of Zn in the composition of the brass is an important factor in increasing the amount of ferrite in the matrix. In the sample with 3 wt.% composites (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e-a), the presence of machining chips in the matrix is ​​observed, which are distributed as dots inside the matrix. The incomplete dissolution of these chips has significantly influenced the distribution of graphite, and thinner graphite layers are observed near the chips, resulting in a fundamentally altered distribution of the graphites throughout the sample. Type A, B, and D graphites with different classes (5 and 6) are seen - according to the ASTM A48 standard. In the sample with 5 wt.%, the amount of non-dissolved chips in the matrix has increased. Close to the interface of the matrix and the swarf, there is a considerable presence of type C graphite, while as one moves further from the swarf, whereas at a distance from the swarf, its distribution resembles that of the composite sample containing 3 wt.%. By etching the 3 wt.% sample in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, a circular ferrite region is formed near the swarf, which is distinct from the matrix. Observations indicate that swarf is found adjacent to the same ferritic region. Moreover, the mold matrix represented in this image features a pearlite-ferrite matrix. In the etched sample of 5 wt.%, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e-b, the amount of pearlite is higher near the swarf, which indicates the presence of the pearlite-reinforcing element, namely copper. At a distance further from the swarf, the amount of ferrite is higher than in the control sample. It can be concluded that the matrix develops through two distinct mechanisms: pearlite formation adjacent to the interface and a ferrite-pearlite mixture in regions further from the interface. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e-b illustrates the melting of the chip throughout the casting process, followed by its solidification within the pearlite matrix, which lacked sufficient time for complete dissolution. The interesting point in the image is the diffusion of graphite towards the brass swarfs, this penetration has reached the interior of the swarfs to some extent. Pearlite is a eutectoid product that is composed of layers of ferrite and cementite, like a fingerprint. The dissolution of copper in the cast iron matrix facilitates the eutectoid transformation, resulting in an increase in the amount of pearlite near the interface where the diffusion rate is highest. Alongside elemental diffusion, a thermodynamic aspect is also present: the existence of swarfs contributes to the formation of new solidification fronts. This elevated cooling rate diminishes the spacing between the layers of pearlite. Both the cementite and ferrite layers are white, but corrosion caused by 2% Nital leads to grain boundary corrosion, and the grain boundaries appear as dark lines. This layer gap is an important factor in the formation of pearlite. When the gap is minimized, the carbon element can diffuse more readily, which promotes the transformation of pearlite. The rate of pearlite formation is controlled by the diffusion of carbon to form a low-carbon ferrite layer and a high-carbon cementite layer, where the presence of brass swarf acts as a feed and shifts the temperature of pearlite formation by heat transfer.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eIn Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, the electron microscope images illustrate the distribution of type A graphite in the GCI matrix. When juxtaposed with Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, which reveals the microstructure of the 1 wt.% Swarf composite, it becomes apparent that the graphite structures are finer in the latter. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e-c presents a sample with a composition of 3 wt.% swarf. This image reveals the interface between the brass swarf and the cast iron matrix. The composite sample shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e-d contains 5 wt.% of swarf. This image provides a clear representation of the structural differences observed in the various regions of the cast iron. In the upper part of the swarf, the E and D type distribution is dominant, while near the swarf, the A distribution is more visible. The shape of the swarf in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e-d is seen as a curve. It is very likely that a significant portion of the swarf melted during casting under high temperatures and created this existing shape. The temperature at which brass melts is between 910\u0026deg;C and 940\u0026deg;C, and at elevated temperatures of 1300\u0026deg;C, the risk of zinc vapor formation becomes markedly high [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. In the two images of Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec and d, two lines are drawn from the matrix region to the swarf region. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows the distribution of elements along these lines. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, the diffusion of zinc and copper elements in the cast iron matrix starts at a distance of 18 \u0026micro;m and continues to a significant extent up to 22 \u0026micro;m. After that, the diffusion rate inside the cast iron matrix decreases, indicating that the diffusion time during the melting and solidification processes was sufficiently appropriate. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e-b, the diffusion rate was notably absent, recorded at around 5 \u0026micro;m. This can be explained by the considerable amount of brass swarf incorporated into the melt, which acted as a chill and led to the formation of new solidification fronts at these lower temperature zones. This rapid solidification, due to the drop in temperature and the strong dependence of diffusion on temperature, significantly reduced the diffusion rate. In both linear distributions of elements within the cast iron matrix, the amount of carbon element sometimes increases greatly, which is fundamentally linked to the presence of the pure graphite phase. The comparison of the two lines within the cast iron matrix demonstrates that the diffusion rates of copper and zinc in the 3 wt. % sample are more effective at longer distances than in the 5 wt.% composites. One important factor for the low diffusion of zinc and nickel elements is the high cooling rate in the 5 wt.% composites. Cooling rates play a crucial role in determining how quickly the elements diffuse. On the other hand, the increased quantity of swarf has facilitated the development of localized zones rich in alloying elements. This situation has led to a reduction rate of diffusion in the sample, primarily due to the occurrence of supersaturation.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe map image presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e details the elemental distribution in the 5wt.% composite sample. Analysis of the image indicates that carbon has not diffused into the brass, and its presence is noted at several specific points. However, the extent of silicon diffusion observed in the swarf is minimal. In addition, there are two points in the image where the silicon concentration is at its highest, indicated by a deep blue color in the swarf. Iron, like carbon, is only found in the cast iron matrix. In this image, copper has the highest diffusion and has moved from the swarf side to the cast iron. The swarf interface has the highest copper content compared to the matrix further away, which can be better understood from Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e-b. Near the swarf, the distinct pearlitic zone, marked by the small size of the pearlitic grains and the close arrangement of the pearlitic layers, reveals the same copper trace that is clearly depicted in this image. Zinc elements, which are heavier than other elements, behave in a similar way to copper, but the diffusion rate of this element is low compared to copper, and its maximum amount is seen in the swarf. However, zinc has a significant diffusion rate compared to other elements. The behavior of alloying elements varies significantly in the presence of a concentration gradient. The diffusion of these elements is inversely proportional to their melting points; thus, elements with lower melting points are associated with higher diffusion coefficients. In the presented image, the diffusion of the two elements zinc and copper was also indicative of this issue. Alongside diffusion, an additional vital process contributes to the dissolution of elements embedded in the matrix. Such as local melting and convection created inside the melt due to the contact of two dissimilar melts. The movement of molten brass and cast iron occurs as a result of the concentration gradient and variations in density, allowing the two melts to interpenetrate through convective processes. This action creates several brass spots inside the cast iron, which creates a larger contact surface for these melts, facilitating diffusion and dissolution. This convection can also cause some casting defects. These casting defects undoubtedly require both substantial and rapid convection. However, the closely matched densities of the two materials hinder this process, resulting in a slower movement of the melts together.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe bar graph presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e illustrates the variations in hardness resulting from the incorporation of the swarf. The addition of 1wt.% of swarf resulted in a hardness increase from 200HB to 212HB. Copper is important factor in reducing the gap of the pearlite layers (ferrite and cementite), which is the same factor that enhances the hardness in samples containing 1wt.% brass [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. In samples with 3wt.% swarf, the hardness is slightly lower than the GCI sample and 197HB, in samples containing 5wt.% swarf, the hardness measures a mere 185HB. This phenomenon is primarily due to the presence of a soft brass phase embedded in the cast iron matrix. Moreover, the D-type graphites incorporated into the 5wt.% composite matrix further reduce the chances of pearlite formation in comparison to other samples. The presence of ferrite is also another reason for reducing hardness due to the softness of this structure. The influence of the pearlitization of copper is recognized as a means of increasing hardness; however, during deformation under load, the existence of soft zones within the cast iron matrix greatly reduces hardness. The presence of these soft zones complicates the behavior of the 5wt.% composite. The Brinell ball serves as an excellent tool for evaluating the hardness of materials characterized by various phases. When force is exerted, it not only impacts the material being tested but also influences the neighboring surfaces and their phases. Furthermore, the presence of the soft zone suggests plastic behavior and leads to an increase in the area of ​​impact and ball depression. The microhardness graph depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, corresponding to the sample with 5wt.%, is provided to facilitate a deeper understanding of the hardness behavior and its alterations in distinct areas of the sample structure. This graph starts from the cast iron matrix and enters the brass region by passing through the interface. Analyzing the graph closely indicates that the microhardness adjacent to the interface is elevated compared to the matrix situated further away. In particular, the maximum microhardness in the cast iron matrix is ​​near the interface. The process of diffusion of the pearlite reinforcing element into the matrix near the interface results in an increased presence of pearlite in that specific region. In contrast, the diffusion of copper in the more distant regions of the matrix is reduced, leading to a decrease in pearlite content, which subsequently enhances the hardness in the areas close to the interface. As the graph enters the brass region, the microhardness decreases significantly and reaches 109 Vickers. In the inner parts of the brass chip, this number becomes even lower and reaches 99 HV. This observation illustrates the non-uniform distribution of hardness throughout the composite sample.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe graph in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e shows the changes in the impact energy of the samples with increasing amounts of brass swarf. The GCI sample demonstrates an impact energy of 3J, a notably low figure. This low value can be attributed to the presence of flaky graphite within the gray cast iron matrix, identified as a site of stress concentration. Consequently, the control sample exhibits brittle characteristics. By adding 1wt.% brass swarf, the impact energy increases by 40% and reaches 4.2J. One of the factors in increasing the impact energy is the finer grain size of the pearlite matrix. The enhancement of pearlite grain quantity plays a crucial role in augmenting impact energy [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. In addition, finer graphite was also an important factor in this. In the composite samples with a concentration of 3wt.%, there was a significant increase in impact energy, which peaked at 5.7J. Conversely, the samples with a concentration of 5wt.% exhibited the highest impact energy, attaining a value of 10.6J. Increasing the impact energy level, in addition to the structure of the cast iron matrix (fine pearlites and fine graphites), has another very important parameter, which is the presence of an undissolved swarf in the cast iron matrix. These swarfs are a major obstacle during crack growth.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e shows scanning electron microscopy (SEM) images of the fractured samples resulting from the impact test. Images labeled a and b depict the fracture surfaces of the GCI samples and the 1wt.% swarf composite sample, respectively. Deep dimples in the images indicate a weak interface between the matrix and graphite and indicate a brittle fracture of the samples. Although this test was performed without creating notches in the fractured samples, the presence of flake dendritic graphite acts like a crack. The tips of these flake graphite act as stress concentration points, highlighting the fact that the graphites themselves are vulnerable areas [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. In Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ec, the fracture surface of the sample with 3wt.% of swarf is observed. A distinct and heterogeneous region, marked by a cast iron matrix, is visible in the middle of the image. This area has developed due to the presence of a brass swarf, which was not adequately eliminated during the melting process. The central area of Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e-d illustrates the region influenced by the swarf. The images depict the varying behaviors of the phases present within the swarf as crack growth occurs, and these behaviors are considered to be key factors in the rise of impact energy. The crack exhibits a crucial shift in its direction as it expands in interaction with the swarf, which itself undergoes a morphological change, and this change is observed at the interface and center of the sample. The presence of a substantial depression and bulge signifies a modification in the fracture direction during the progression of crack growth. In fact, this phenomenon stops the growth of the crack, and when the crack enters the brass zone, the deep depressions and peaks become less pronounced, and replaced by more gradual depressions and peaks, along with the formation of microvoids. In Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e-d, the same issue is repeated, but the amount of swarf in this image is higher and in addition, the interface between the matrix fracture surface and the swarf has formed a larger ring. The interface region in the 3 and 5 wt.% samples exhibit a more distinct contrast from both the matrix and the swarf. In addition to the presence of a swarf, the cast iron area around the swarf has slightly finer dimples compared to the GCI matrix. This could be due to the fine grain size created by the high cooling rate caused by the presence of a brass swarf. The interface observations in the image confirm that the deep dimples resulting from the weak interface of graphite with the iron matrix have been replaced by finer microvoids and depressions. Although the amount of swarf in the image is low, the effect of this parameter is much higher in the fractured image. The analysis of the GCI and 1wt.% composite samples indicates a consistent brittle fracture mechanism. In contrast, the samples containing swarf at 3 and 5wt.% show more complex behavior and mechanism due to the presence of swarf in the matrix. Upon hammer impact, the crack within the cast iron matrix propagated in a brittle manner, altering its path when it encountered the interface. In the brass swarf region, the fracture behavior transitioned to a softer, more ductile mode. Indeed, the mechanism of fracture involves both ductile and brittle characteristics. Furthermore, the brass swarf layer serves as a shock-absorbing medium during impacts, thereby mitigating the initial effects of such impacts.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"4- Conclusion","content":"\u003cp\u003eThe present research focuses on the effects of adding brass alloy machining swarf to hypoeutectic gray cast iron, and the significant findings are summarized as follows:\u003c/p\u003e\n\u003col\u003e\n \u003cli\u003eThe addition of 1wt.% brass swarf modified the graphite distribution, shifting it from type A to types E and A, while also resulting in a finer graphite and an enhanced quantity of fine pearlite grains. Increasing the amount of swarf to 3 and 5wt.%, in addition, to type A, E graphites, type D, and C graphites also increased the amount of pearlite grains due to the presence of undissolved swarf in the field due to the penetration of the copper element and also the high solidification rate. By analyzing the distribution line and map, researchers observed a substantial diffusion of copper in the matrix located near the swarf. Zinc element was also observed in abundance in areas near the swarf.\u003c/li\u003e\n \u003cli\u003eBy adding 1wt.% of swarf to cast iron, the hardness changed from 200HB to 212HB, which was influenced by factors such as fine grain size and pearlitic matrix. By increasing the swarf content to 3 and 5 wt.%, the hardness decreased to 197HB and 185HB, respectively. Analysis of the microhardness graph illustrated the hardness of the cast iron matrix located near the maximum swarf. This region exhibited a pronounced pearlitic structure, significantly influenced by the presence of nickel. In contrast, The hardness in the swarf was minimal and the hardness of the swarf was measured to be 99 HV.\u003c/li\u003e\n \u003cli\u003eThe impact energy of the swarf increased by 40% with the addition of 1wt.% swarf and reached 4.2 Joules. Increasing the amount of swarf to 3 and 5 wt.% by weight, this value increased to 5.7J and 10.2J, which was very high compared to the control sample. The analysis of the fracture mechanism revealed that the gray cast iron exhibited brittleness attributed to the presence of flake graphite. Conversely, samples with 5 and 3wt.% of swarf exhibited cracks that initiated and propagated within the cast iron matrix. The interface between the swarf and the matrix presented a challenge to the propagation of these cracks. After the crack direction was altered at this interface, the brass soft zone revealed a ductile fracture characteristic. This led to the creation of a complex fracture mechanism and a mixture of brittle and ductile fracture in the composite samples with 3 and 5 wt.% by weight of the swarf.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/li\u003e\n \u003cli\u003eThe authors have no competing interests to declare that are relevant to the content of this article.\u003c/li\u003e\n \u003cli\u003eAll authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.\u003c/li\u003e\n \u003cli\u003eThe authors have no financial or proprietary interests in any material discussed in this article.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003efunding statement:\u003c/strong\u003e\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eThe authors did not receive support from any organization for the submitted work.\u003c/li\u003e\n \u003cli\u003eNo funding was received to assist with the preparation of this manuscript.\u003c/li\u003e\n \u003cli\u003eNo funding was received for conducting this study.\u003c/li\u003e\n \u003cli\u003eNo funds, grants, or other support was received.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003edata availability statement\u003cspan dir=\"RTL\"\u003e:\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data is available on reasonable request from the corresponding author.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eMahdi Ranjbar: Draft writer, executive activitiesZahra Sadat Seyed Raoofi: Supervisor - ReviewSeyed Hossein Razavi: Consultant - ReviewYazdan Shajari: Consultant - Methodologist - ReviewAhad Nasimi: Executive activities - Characterization testsMilad Shadi: Executive activities - Casting repetition - Sample preparation\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eZhang, S., Ran, Y., Murphy, A., Zhang, G. \u0026amp; Wang, W. 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H. A. a. E. T. Taşli\u0026ccedil;ukur, Characterization of microstructure and fracture behavior of GG20 and GG25 cast iron materials used in valves. In Proceedings of the 21st International Conference on Metallurgy and Materials, Brno, Czech Republic,. 23\u0026ndash;25. (2012).\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":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Gray cast iron, copper alloy, cast iron composite, fracture energy","lastPublishedDoi":"10.21203/rs.3.rs-5988603/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5988603/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this study, the effects of brass machining swarfs with different weight percentages on cast iron were investigated. The addition of 1 wt.% swarf contributed to the finer characteristics of the graphites categorized as types A and E while simultaneously increasing the quantity of pearlite grains present. When the amount of swarfs was increased to 3 and 5 wt.%, the graphite became finer due to rapid solidification, and a transitional interface of pearlite was also observed. The addition of 1 wt.% swarf to the cast iron led to an increase in hardness from 200 HB to 212 HB. However, as the swarf content increased, a reduction in hardness was observed, with the composites containing 3 wt.% and 5 wt.% swarf achieving hardness values of 197 HB and 185 HB, respectively. This phenomenon is linked to the presence of the softer brass phase in the composite structure. The microhardness of these swarfs was measured at approximately 99 Vickers, which was the minimum value. The soft phase of the swarf had a positive effect on increasing the impact energy due to ductile fracture, whereas the absence of the swarf led to brittle fracture in gray cast iron and the 1 wt.% composite. The impact energies of graycast iron and the 1 wt.%, 3 wt.% and 5 wt.% composites were measured to be 3, 4.2, 5.7, and 10.6 Joules, respectively.\u003c/p\u003e","manuscriptTitle":"Effect of Adding Machining Swarf of Brass Alloy on the Microstructure and Toughness of Gray Cast Iron","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-13 12:22:50","doi":"10.21203/rs.3.rs-5988603/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-03-20T05:43:29+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-03-09T23:22:21+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-25T10:03:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"25176720028784192608868009594397747239","date":"2025-02-18T00:26:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"333337395039206410703214524688740277405","date":"2025-02-17T18:24:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-02-17T17:55:59+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-02-17T16:23:30+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-02-13T05:27:55+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-02-11T11:57:01+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-02-08T15:10:56+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"05db6bdd-f5d6-46c2-90a5-7ee2db3763f3","owner":[],"postedDate":"February 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":44168231,"name":"Physical sciences/Engineering"},{"id":44168232,"name":"Physical sciences/Materials science"},{"id":44168233,"name":"Physical sciences/Materials science/Structural materials"}],"tags":[],"updatedAt":"2026-02-23T16:05:47+00:00","versionOfRecord":{"articleIdentity":"rs-5988603","link":"https://doi.org/10.1038/s41598-026-40916-6","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2026-02-20 15:57:50","publishedOnDateReadable":"February 20th, 2026"},"versionCreatedAt":"2025-02-13 12:22:50","video":"","vorDoi":"10.1038/s41598-026-40916-6","vorDoiUrl":"https://doi.org/10.1038/s41598-026-40916-6","workflowStages":[]},"version":"v1","identity":"rs-5988603","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5988603","identity":"rs-5988603","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}