Effects of Alternating Cusp-Shaped Magnetic Field on Penetration Behavior, Microstructure, and Mechanical Properties in TIG Welding

Effects of Alternating Cusp-Shaped Magnetic Field on Penetration Behavior, Microstructure, and Mechanical Properties in TIG Welding | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effects of Alternating Cusp-Shaped Magnetic Field on Penetration Behavior, Microstructure, and Mechanical Properties in TIG Welding Hui Huang, Yi Luo, Xiaojun Deng, Junxiao Deng, Zhang Ma This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8519968/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study investigates the effects of an alternating cusp-shaped magnetic field on the penetration behavior, microstructure, and mechanical properties of TIG-welded 304 stainless steel. Experimental results demonstrate that the applied magnetic field dynamically alters arc morphology through Lorentz forces, cyclically compressing or expanding the arc. This alteration leads to a reduced effective arc area on the workpiece, significantly enhancing penetration depth. At optimal parameters (25A excitation current, 200Hz frequency), the penetration depth increased to 3.55 mm, doubling compared to non-magnetic welding. Microstructural analysis revealed substantial grain refinement, with an average grain size reduction of 41% under the 25A magnetic field, alongside a weakened {001}-cube texture, where the maximum pole density decreased from 8.10 to 3.13. The suppression of this texture, which is detrimental to tensile strength, is attributed to disrupted heat flow alignment and continuous oscillation-induced variations in the temperature field during solidification. Consequently, the tensile strength of welded joint improved to 777 MPa (99% of the base metal), primarily due to grain boundary strengthening and randomized grain orientation. These findings highlight the alternating cusp-shaped magnetic field as an effective method to enhance TIG welding efficiency by optimizing penetration and microstructure, providing insights into texture control and mechanical property enhancement in welded joints. Magnetic field Arc shape Penetration depth Microstructure Texture Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1 Introduction The application of a magnetic field in arc welding can adjust the morphology of the arc, enhance arc stability, regulate the transfer of molten droplets, improve the solidification of the molten pool, and optimize the appearance of the weld. This method is recognized as an efficient welding technique. Consequently, the magnetically controlled arc welding process has been employed to enhance both weld quality and productivity [ 1 , 2 ]. The introduction of an external magnetic field during the welding process was first proposed by Brown in 1962 [ 3 ]. Subsequent literature has confirmed that the morphology of the arc plasma can be significantly influenced by an external magnetic field. Currently, researchers have explored various configurations of magnetic fields, including axial, transverse, rotating, and DC cusp-shaped magnetic fields, in the welding process. For instance, Chang et al. [ 4 ] employed a high-frequency axial magnetic field in short-circuit gas metal arc welding (GMAW) and observed that it enhanced weld shaping, reduced the spatter rate, and improved weld quality by affecting the transition of arc plasma and molten droplets. Nomura et al. [ 5 ] demonstrated that a constant cusp-shaped magnetic field can modify the motion of charged particles within the arc plasma, resulting in a compressed cross-section that takes on an elliptical shape. Liu et al. [ 6 ] utilized a permanent magnet to generate a cusp-shaped magnetic field, which improved the penetration behavior in tungsten inert gas (TIG) welding; their results indicated that a cusp-shaped magnetic field with a small polar angle further enhanced the penetration capability of the K-TIG arc. Additionally, Baskoro et al. [ 7 ] examined the effects of a rotating magnetic field, produced by eight sequentially activated induction coils, on the arc shape and weld seam. Wang et al. [ 8 ] and Sun et al. [ 9 ] implemented a transverse magnetic field to improve the distribution of arc pressure on both the bottom and sidewalls, thereby preventing insufficient fusion on the sidewalls and enhancing the efficiency and quality of the weld. Currently, regarding the aforementioned types of magnetic fields commonly utilized in magnetron arc welding, most studies have concentrated on the effects of these magnetic fields on penetration depth, arc morphology, droplet transitions, and so forth. However, there is a notable lack of comprehensive analysis concerning the weld microstructure, particularly in relation to the correlation between microstructure and mechanical properties. This paper presents a designed experimental system capable of generating an alternating cusp-shaped magnetic field, and it investigates the arc morphology, penetration depth, microstructure, and mechanical property characteristics produced under various excitation currents of the alternating cusp-shaped magnetic field. This study lays a theoretical foundation for systematically optimizing the process of magnetically controlled arc welding technology to achieve high-quality welds. 2 Experimental details The magnetically controlled welding experiment system is illustrated in Fig. 1 . The welding power source utilized is a direct current (DC) tungsten inert gas (TIG) welding device. An alternating cusp-shaped magnetic field is generated by four evenly distributed magnetic poles. The workpiece consists of 304 stainless steel with dimensions of 140 mm × 20 mm × 5 mm. The experimental parameters are detailed in Table 1 . The tungsten electrode has a diameter of 2.4 mm and a top angle of 50°. During the welding experiment, the welding current is set at 150 A, the arc length is maintained at 4 mm, and pure argon is employed as the shielding gas with a flow rate of 10 L/min. The excitation power supply is a multifunctional high-frequency unit capable of providing both alternating current (AC) and direct current (DC) pulses. In this study, AC current pulses are utilized as the excitation current. To ensure comparability of the experimental results, the frequency of the excitation current pulse is kept constant at 200 Hz. The variability of the excitation effect is achieved by adjusting the excitation current values, with three specific currents of 5 A, 25 A, and 35 A being employed. The experiments analyze the characteristics of weld macro-forming, microstructure, and mechanical properties to assess the impact of the alternating cusp-shaped magnetic field on the quality of TIG welding. Table 1 Main welding process parameters Parameter items Value Welding current I/A 150 Arc length L/mm 4 Excitation current I e /A 0, 5, 25, 35 Excitation frequency f /Hz 200 3 Results and discussions 3.1 Arc morphology and weld macro-forming In the absence of an alternating cusp-shaped magnetic field, the TIG welding arc typically exhibits a bell jar shape, with a circular cross-section as shown in Fig. 2 . However, when an alternating cusp-shaped magnetic field is applied, the arc plasma undergoes significant changes due to the influence of the Lorentz force. During the positive cycle, the arc behaves as a charged conductor, where the Lorentz forces acting on the two sides direct towards the center of the arc, while the forces on the opposite sides act in opposing directions. This results in the arc being compressed into a sheet. Conversely, during the negative cycle, the direction of the arc force reverses. The continual alteration in the force direction leads to periodic expansion and compression, causing the base of the arc to become sharp. The shape of the molten pool is influenced by the configuration of the arc. The molten pool undergoes three distinct stages of transformation. During the positive cycle, the shape of the molten pool transitions from a circular form to an elliptical one, while in the recovery stage, it returns to a circular shape. Conversely, in the negative cycle, the forces exerted are opposite to those during the positive half-cycle. In the alternating cusp-shaped magnetic field, the arc is compressed, indicating that although the molten pool retains a circular shape, the area interacting with the workpiece is reduced. As shown in Fig. 3 , when the alternating cusp-shaped magnetic field is not applied, the arc burns normally with a shallow penetration depth of only 1.68 mm. When the frequency of the alternating cusp-shaped magnetic field is fixed at 200 Hz, the penetration depth initially increases and then decreases with the rise in excitation current, reaching a maximum of 3.55 mm at 25 A. The study results from Wu et al. demonstrated that the arc pressure increases and subsequently decreases with the excitation current within a certain range, indicating a process of expansion, contraction, and final expansion of the arc [ 3 ]. When the alternating cusp-shaped magnetic field is applied, the penetration depth also increases and then decreases in response to the arc pressure. The asymmetry of the weld pool may arise from the fact that the oscillation center is not aligned with the center of the weld pool, a condition caused by the arc swing. The alternating cusp-shaped magnetic field induces a Lorentz force on both the arc and the liquid metal within the molten pool, leading to a rotational motion of the molten pool. When the magnetic field reverses, the direction of the arc's movement follows suit; however, the molten pool cannot immediately reverse due to its significant inertia, continuing to move in the original direction until the reversing torque is sufficient to overcome this inertia. This issue can be mitigated by optimizing the frequency and magnetic field strength. As the excitation current increases, a stronger magnetic field influences the molten pool through the arc, resulting in a smaller shift in the oscillation center and a tighter constraint on the arc, thereby improving the asymmetry of the pool. 3.2 Microstructure Figure 4 illustrates the IPF coloring diagram under conditions both without a magnetic field and with an alternating cusp-shaped magnetic field characterized by varying parameters. In this diagram, a green color bias denotes a grain orientation preferentially aligned with the direction, a red color bias indicates a grain orientation favoring the direction, and a blue color bias signifies a grain alignment biased towards the direction. In the absence of the alternating cusp-shaped magnetic field, the grain color predominantly appears red, suggesting a strong alignment towards the direction. However, the introduction of the alternating cusp-shaped magnetic field results in a weakening of this orientation tendency. This is further evidenced by the pole figure, which shows a decrease in maximum pole density from 8.10 to 3.13. A lower pole density reflects a more uniform distribution across the spherical surface, indicating that grain growth and orientation become increasingly random, leading to a reduction in the preferred grain orientation. Without the application of an alternating cusp-shaped magnetic field, the EBSD results indicate that the grains are coarse, with an average grain size of 80.06 µm. When an alternating cusp-shaped magnetic field is applied, with a 5A excitation current and a frequency of 200Hz, grain refinement is not significant, yielding an average grain size of 72.49 µm. This limited refinement is primarily attributed to the insufficient electromagnetic force, which does not provide enough stirring effect to disrupt the columnar crystals, resulting in relatively large grains. However, when the alternating cusp-shaped magnetic field is applied at a higher excitation current of 25A and the same frequency of 200Hz, the average grain size decreases to 46.91 µm, representing a reduction of approximately 41%. This reduction is due to the alternating changes in the Lorentz force acting on the arc, which stirs the molten pool. The oscillation of the arc leads to the breaking or bending of pre-nucleated dendrites, thereby disrupting their normal growth direction. The stirring of the molten pool by the arc facilitates the breaking of growing dendrites, promoting new heterogeneous nucleation and increasing the nucleation rate. Consequently, the emergence of numerous fine columnar crystals is observed, resulting in a decrease in average grain size. As illustrated in Fig. 5 , following the application of the alternating cusp-shaped magnetic field, there is a notable increase in both the number and length of grain boundaries, along with a significant rise in the proportion of smaller grains. 3.3 Mechanical properties Figure 6 shows the tensile stress-deformation curve of the welded joint. After the magnetic field is applied, the tensile strength of the welded joint is 777 MPa, which is about 99% of the base metal, ensuring good strength. In general, metal is strengthened in four main ways: work hardening, solid solution strengthening, precipitation strengthening, and fine-grain strengthening. Texture, grain boundary, grain size, and fracture mode play an important role in the improvement of tensile properties for the present experimental magnetron welding process [ 10 , 11 ]. From the Hall-Petch formula, it can be concluded that grain refinement directly leads to an increase in grain boundary strengthening increments. $$\:{\Delta\:}{\sigma\:}\text{G}\text{B}=\text{K}\text{y}\sqrt{\frac{1}{d}}$$ ΔσGB represents the increment in crystal boundary enhancement, Ky is the Hall-Petch coefficient, and d denotes the grain size. Substituting the average grain size into the formula reveals that the contribution rate of grain boundaries to strength is 5%, 30%, and 11% when the external magnetic field is set to 5A, 25A, and 35A, respectively. According to dislocation theory, a smaller grain size results in a higher number of grain boundaries within the same volume, which hinders dislocation slip. Consequently, finer grain sizes exhibit a more pronounced hindrance effect on dislocation slip, thereby enhancing the tensile strength of the structure. Notably, there is little variation in strength and elongation between excitation currents of 25A and 35A. This paper posits that the uneven grain size at an excitation current of 25A mitigates some of the benefits associated with fine grain strengthening. Figure 7 shows the orientation and quantity of grains are influenced by varying excitation currents and frequencies. It is believed that the {001}-cube texture is unfavorable to the tensile strength, but the initial fiber texture (IFT) is favorable to the crystal slip, which can improve the tensile properties and anisotropy [ 12 , 13 ]. For the without magnetic welding and the welding process with the addition of a weaker magnetic field, the volume of the molten pool is relatively small, and the columnar grains grow almost parallel to the direction due to the high solidification rate. And the heat is concentrated in the middle region and forms the temperature field direction which is highly consistent with the heat flow. Therefore, the {001}-cube texture is mainly formed. For the strong magnetic field welding process, both the oscillating heat flux and the direction of the temperature field vary continuously. The formation of the {001}-cube texture occurs only at a specific time, not during the entire solidification process [ 14 ]. Therefore, the {001}-cube texture content of the sample is the lowest for the stronger magnetic field welding process, the tensile strength is high. 4 Conclusion In the welding process, an alternating cusp-shaped magnetic field used in TIG welding can significantly influence the arc shape, penetration, microstructure, and mechanical properties. (1) When the alternating cusp-shaped magnetic field is applied, the arc can be significantly compressed or expanded compared to the absence of a magnetic field. The penetration depth increases, reaching a maximum value of 3.55 mm at a magnetic field strength of 25A and a frequency of 200Hz. (2) Microscopic analysis results indicate that the application of the alternating cusp-shaped magnetic field can refine the grains, alter the maximum heat dissipation direction, and enhance the random distribution of grains. At a magnetic field strength of 25A and a frequency of 200Hz, the average grain size is reduced by approximately 41%, while the area of the grain boundary increases, resulting in the weakest preferred orientation of the grains. (3) The improvement in tensile strength is explained in terms of texture and grain size reduction. It is posited that the {001}-cube texture is detrimental to tensile strength. In the absence of a magnetic field and during the welding process with the addition of a weaker alternating cusp magnetic field, the {001}-cube texture is predominantly formed. In contrast, during the strong alternating cusp-shaped magnetic field welding process, the temperature field direction is no longer aligned with the heat flow due to continuous oscillations affecting both parameters. Consequently, the formation of the {001}-cube texture occurs only at specific times, leading to the lowest content of this texture in the samples. (4) The application of the alternating cusp-shaped magnetic field can address the limitations of traditional TIG welding penetration and refine the grain structure, thereby facilitating the realization of efficient welding. Declarations Acknowledgements This work was supported by Natural Science Foundation Project of Chongqing Science and Technology Bureau of China (Grant No. cstc2021jcyj-msxmX0189). Funding This work was supported by Natural Science Foundation Project of Chongqing Science and Technology Bureau of China (Grant No. cstc2021jcyj-msxmX0189). Conflicts of interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled “Effects of Alternating Cusp-Shaped Magnetic Field on Penetration Behavior, Microstructure, and Mechanical Properties in TIG Welding”. Availability of data and material The datasets used and analyzed during the current study are available from the corresponding author on reasonable request. Code availability Not applicable Authors' contributions Huang and Luo carried out the experiment analysis and writing. Deng participated in the design of the experiment. Deng and Ma participated in the data validation. Ethics approval Not applicable Consent to participate We declare that all authors consent to participate in the work in this paper. Consent for publication We declare that all authors consent to publish the work and research results in this paper. References Jiang SY, Wang XW, Chen HM, Liu P. The impact of adscititious longitudinal magnetic field on CO 2 welding process, Adv Mater Res., 2012, 538-541: 1447–1450. Chen Y, Sui FF, Cong KL, Yan XQ, Zhang GY, Guan SK. Effects of shielding gas and magnetic field on characteristics of AZ31 magnesium alloy by TIG welding. Mater Sci Forum, 2012, 704-705: 1186–1196. Wu H, Chang YL, Lu L, Bai J. Review on magnetically controlled arc welding process. Int. J. Adv. Manuf. Technol., 2017, 91: 4263–4273. Chang YL, Liu XL, Lu L, Babkin AS, Lee BY, Gao F. Impacts of external longitudinal magnetic field on arc plasma and droplet during short-circuit GMAW. Int. J. Adv. Manuf. Technol., 2014, 70: 1543–1553. Nomura K, Ogino Y, Hirata Y. 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19:37:45","extension":"png","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":262184,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/c34f79ee53b0b562b23b1089.png"},{"id":100919096,"identity":"b71f331e-d277-42a4-9239-ce467132202c","added_by":"auto","created_at":"2026-01-22 19:37:45","extension":"png","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":464856,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/575c6024e7c95e04129acb13.png"},{"id":100951049,"identity":"d9a0fb3c-4e64-4648-9aa9-e03b0381f97f","added_by":"auto","created_at":"2026-01-23 07:09:54","extension":"png","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":35810,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/da8a037a9b462f133c4c1f23.png"},{"id":100919103,"identity":"a99a2ae2-fd56-4d40-99b5-d49435edd73b","added_by":"auto","created_at":"2026-01-22 19:37:45","extension":"png","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":308451,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/fb92204bc03c21da7b43a9b3.png"},{"id":100950856,"identity":"795d6c12-01df-4928-9fc3-4f3d69781c04","added_by":"auto","created_at":"2026-01-23 07:09:23","extension":"xml","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":50968,"visible":true,"origin":"","legend":"","description":"","filename":"WITWD26000090structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/eb7a5abda4c9bb0506bae104.xml"},{"id":100919100,"identity":"7149967b-b545-4cbc-b840-368fb1d5701e","added_by":"auto","created_at":"2026-01-22 19:37:45","extension":"html","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":56715,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/a773f997443730e11758fd8b.html"},{"id":100919078,"identity":"0336901d-1107-4126-a8c0-1177b045b297","added_by":"auto","created_at":"2026-01-22 19:37:45","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":62151,"visible":true,"origin":"","legend":"\u003cp\u003eMagnetic Control TIG Welding Experimental System.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/577ce2af804d63931200c960.jpeg"},{"id":100919079,"identity":"ca6d0c98-53ab-4b07-b320-6162ae96d869","added_by":"auto","created_at":"2026-01-22 19:37:45","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":241818,"visible":true,"origin":"","legend":"\u003cp\u003eEffects of alternating cusp-shaped magnetic field on arc and molten pool morphology.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/80f67335c0b5782ff1923d6a.jpeg"},{"id":100919080,"identity":"7f8cd364-c33f-42a8-8c8c-730ab20d3aa5","added_by":"auto","created_at":"2026-01-22 19:37:45","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":65204,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of excitation current on the weld penetration depth of the sample.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/8d75639921d5c1bd8d013119.jpeg"},{"id":100951502,"identity":"99b465ae-e95b-438d-a322-1589935eb135","added_by":"auto","created_at":"2026-01-23 07:10:43","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":358937,"visible":true,"origin":"","legend":"\u003cp\u003eIPF coloring map, ​Polar and antipodal plots under conditions both without a magnetic field and with an alternating cusp-shaped magnetic field characterized by varying excitation current and frequency, (a) Without magnetic, (b) 5A, 200Hz, (c) 25A, 200Hz, (d) 35A, 200Hz.\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/e7974f9ab52278d077004da0.jpeg"},{"id":100919087,"identity":"b6d68e10-e74d-4201-9359-41ee2e84d49d","added_by":"auto","created_at":"2026-01-22 19:37:45","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":709699,"visible":true,"origin":"","legend":"\u003cp\u003eGrain boundary and grain size distribution charts are presented for the following conditions: (a) without magnetic influence and (b) at 5A excitation current, 200Hz frequency, (c) at 25A excitation current, 200Hz frequency, and (d) at 35A excitation current, 200Hz frequency.\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/7c73251dd217ab5f36cf284d.jpeg"},{"id":100951211,"identity":"97d4dbfb-7d4b-4224-babe-7e98f31ed2bd","added_by":"auto","created_at":"2026-01-23 07:10:14","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":106095,"visible":true,"origin":"","legend":"\u003cp\u003eStress-deformation curve.\u003c/p\u003e","description":"","filename":"floatimage6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/3730b9182ec1eb6e90f43f77.jpeg"},{"id":100919090,"identity":"f5affd81-d69d-4366-b3de-60e2b38b2120","added_by":"auto","created_at":"2026-01-22 19:37:45","extension":"jpeg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":341115,"visible":true,"origin":"","legend":"\u003cp\u003eThe orientation and quantity of \u0026lt;100\u0026gt; grains are influenced by varying excitation currents and frequencies, (a) Without magnetic, (b) 5A, 200Hz, (c) 25A, 200Hz, (d) 35A,200Hz\u003c/p\u003e","description":"","filename":"floatimage7.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/8f669639225fd853de8d6de5.jpeg"},{"id":107480340,"identity":"92c05915-d0a8-4e79-9560-2f756250a769","added_by":"auto","created_at":"2026-04-22 02:08:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2050298,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8519968/v1/c12dee55-312e-4895-9cb2-168c58a1b49e.pdf"}],"financialInterests":"","formattedTitle":"Effects of Alternating Cusp-Shaped Magnetic Field on Penetration Behavior, Microstructure, and Mechanical Properties in TIG Welding","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eThe application of a magnetic field in arc welding can adjust the morphology of the arc, enhance arc stability, regulate the transfer of molten droplets, improve the solidification of the molten pool, and optimize the appearance of the weld. This method is recognized as an efficient welding technique. Consequently, the magnetically controlled arc welding process has been employed to enhance both weld quality and productivity [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe introduction of an external magnetic field during the welding process was first proposed by Brown in 1962 [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Subsequent literature has confirmed that the morphology of the arc plasma can be significantly influenced by an external magnetic field. Currently, researchers have explored various configurations of magnetic fields, including axial, transverse, rotating, and DC cusp-shaped magnetic fields, in the welding process. For instance, Chang et al. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] employed a high-frequency axial magnetic field in short-circuit gas metal arc welding (GMAW) and observed that it enhanced weld shaping, reduced the spatter rate, and improved weld quality by affecting the transition of arc plasma and molten droplets. Nomura et al. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] demonstrated that a constant cusp-shaped magnetic field can modify the motion of charged particles within the arc plasma, resulting in a compressed cross-section that takes on an elliptical shape. Liu et al. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] utilized a permanent magnet to generate a cusp-shaped magnetic field, which improved the penetration behavior in tungsten inert gas (TIG) welding; their results indicated that a cusp-shaped magnetic field with a small polar angle further enhanced the penetration capability of the K-TIG arc. Additionally, Baskoro et al. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] examined the effects of a rotating magnetic field, produced by eight sequentially activated induction coils, on the arc shape and weld seam. Wang et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] and Sun et al. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] implemented a transverse magnetic field to improve the distribution of arc pressure on both the bottom and sidewalls, thereby preventing insufficient fusion on the sidewalls and enhancing the efficiency and quality of the weld.\u003c/p\u003e \u003cp\u003eCurrently, regarding the aforementioned types of magnetic fields commonly utilized in magnetron arc welding, most studies have concentrated on the effects of these magnetic fields on penetration depth, arc morphology, droplet transitions, and so forth. However, there is a notable lack of comprehensive analysis concerning the weld microstructure, particularly in relation to the correlation between microstructure and mechanical properties. This paper presents a designed experimental system capable of generating an alternating cusp-shaped magnetic field, and it investigates the arc morphology, penetration depth, microstructure, and mechanical property characteristics produced under various excitation currents of the alternating cusp-shaped magnetic field. This study lays a theoretical foundation for systematically optimizing the process of magnetically controlled arc welding technology to achieve high-quality welds.\u003c/p\u003e"},{"header":"2 Experimental details","content":"\u003cp\u003eThe magnetically controlled welding experiment system is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The welding power source utilized is a direct current (DC) tungsten inert gas (TIG) welding device. An alternating cusp-shaped magnetic field is generated by four evenly distributed magnetic poles. The workpiece consists of 304 stainless steel with dimensions of 140 mm \u0026times; 20 mm \u0026times; 5 mm. The experimental parameters are detailed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The tungsten electrode has a diameter of 2.4 mm and a top angle of 50\u0026deg;. During the welding experiment, the welding current is set at 150 A, the arc length is maintained at 4 mm, and pure argon is employed as the shielding gas with a flow rate of 10 L/min. The excitation power supply is a multifunctional high-frequency unit capable of providing both alternating current (AC) and direct current (DC) pulses. In this study, AC current pulses are utilized as the excitation current. To ensure comparability of the experimental results, the frequency of the excitation current pulse is kept constant at 200 Hz. The variability of the excitation effect is achieved by adjusting the excitation current values, with three specific currents of 5 A, 25 A, and 35 A being employed. The experiments analyze the characteristics of weld macro-forming, microstructure, and mechanical properties to assess the impact of the alternating cusp-shaped magnetic field on the quality of TIG welding.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMain welding process parameters\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter items\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWelding current I/A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArc length L/mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExcitation current I\u003csub\u003ee\u003c/sub\u003e/A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0, 5, 25, 35\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExcitation frequency \u003cem\u003ef\u003c/em\u003e/Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e200\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"3 Results and discussions","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Arc morphology and weld macro-forming\u003c/h2\u003e \u003cp\u003eIn the absence of an alternating cusp-shaped magnetic field, the TIG welding arc typically exhibits a bell jar shape, with a circular cross-section as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. However, when an alternating cusp-shaped magnetic field is applied, the arc plasma undergoes significant changes due to the influence of the Lorentz force. During the positive cycle, the arc behaves as a charged conductor, where the Lorentz forces acting on the two sides direct towards the center of the arc, while the forces on the opposite sides act in opposing directions. This results in the arc being compressed into a sheet. Conversely, during the negative cycle, the direction of the arc force reverses. The continual alteration in the force direction leads to periodic expansion and compression, causing the base of the arc to become sharp.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe shape of the molten pool is influenced by the configuration of the arc. The molten pool undergoes three distinct stages of transformation. During the positive cycle, the shape of the molten pool transitions from a circular form to an elliptical one, while in the recovery stage, it returns to a circular shape. Conversely, in the negative cycle, the forces exerted are opposite to those during the positive half-cycle. In the alternating cusp-shaped magnetic field, the arc is compressed, indicating that although the molten pool retains a circular shape, the area interacting with the workpiece is reduced.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, when the alternating cusp-shaped magnetic field is not applied, the arc burns normally with a shallow penetration depth of only 1.68 mm. When the frequency of the alternating cusp-shaped magnetic field is fixed at 200 Hz, the penetration depth initially increases and then decreases with the rise in excitation current, reaching a maximum of 3.55 mm at 25 A. The study results from Wu et al. demonstrated that the arc pressure increases and subsequently decreases with the excitation current within a certain range, indicating a process of expansion, contraction, and final expansion of the arc [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. When the alternating cusp-shaped magnetic field is applied, the penetration depth also increases and then decreases in response to the arc pressure.\u003c/p\u003e \u003cp\u003eThe asymmetry of the weld pool may arise from the fact that the oscillation center is not aligned with the center of the weld pool, a condition caused by the arc swing. The alternating cusp-shaped magnetic field induces a Lorentz force on both the arc and the liquid metal within the molten pool, leading to a rotational motion of the molten pool. When the magnetic field reverses, the direction of the arc's movement follows suit; however, the molten pool cannot immediately reverse due to its significant inertia, continuing to move in the original direction until the reversing torque is sufficient to overcome this inertia. This issue can be mitigated by optimizing the frequency and magnetic field strength. As the excitation current increases, a stronger magnetic field influences the molten pool through the arc, resulting in a smaller shift in the oscillation center and a tighter constraint on the arc, thereby improving the asymmetry of the pool.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Microstructure\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e illustrates the IPF coloring diagram under conditions both without a magnetic field and with an alternating cusp-shaped magnetic field characterized by varying parameters. In this diagram, a green color bias denotes a grain orientation preferentially aligned with the \u0026lt;\u0026thinsp;101\u0026thinsp;\u0026gt;\u0026thinsp;direction, a red color bias indicates a grain orientation favoring the \u0026lt;\u0026thinsp;001\u0026thinsp;\u0026gt;\u0026thinsp;direction, and a blue color bias signifies a grain alignment biased towards the \u0026lt;\u0026thinsp;111\u0026thinsp;\u0026gt;\u0026thinsp;direction. In the absence of the alternating cusp-shaped magnetic field, the grain color predominantly appears red, suggesting a strong alignment towards the \u0026lt;\u0026thinsp;001\u0026thinsp;\u0026gt;\u0026thinsp;direction. However, the introduction of the alternating cusp-shaped magnetic field results in a weakening of this\u0026thinsp;\u0026lt;\u0026thinsp;001\u0026thinsp;\u0026gt;\u0026thinsp;orientation tendency. This is further evidenced by the pole figure, which shows a decrease in maximum pole density from 8.10 to 3.13. A lower pole density reflects a more uniform distribution across the spherical surface, indicating that grain growth and orientation become increasingly random, leading to a reduction in the preferred grain orientation.\u003c/p\u003e \u003cp\u003eWithout the application of an alternating cusp-shaped magnetic field, the EBSD results indicate that the grains are coarse, with an average grain size of 80.06 \u0026micro;m. When an alternating cusp-shaped magnetic field is applied, with a 5A excitation current and a frequency of 200Hz, grain refinement is not significant, yielding an average grain size of 72.49 \u0026micro;m. This limited refinement is primarily attributed to the insufficient electromagnetic force, which does not provide enough stirring effect to disrupt the columnar crystals, resulting in relatively large grains. However, when the alternating cusp-shaped magnetic field is applied at a higher excitation current of 25A and the same frequency of 200Hz, the average grain size decreases to 46.91 \u0026micro;m, representing a reduction of approximately 41%. This reduction is due to the alternating changes in the Lorentz force acting on the arc, which stirs the molten pool. The oscillation of the arc leads to the breaking or bending of pre-nucleated dendrites, thereby disrupting their normal growth direction. The stirring of the molten pool by the arc facilitates the breaking of growing dendrites, promoting new heterogeneous nucleation and increasing the nucleation rate. Consequently, the emergence of numerous fine columnar crystals is observed, resulting in a decrease in average grain size. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, following the application of the alternating cusp-shaped magnetic field, there is a notable increase in both the number and length of grain boundaries, along with a significant rise in the proportion of smaller grains.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Mechanical properties\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e shows the tensile stress-deformation curve of the welded joint. After the magnetic field is applied, the tensile strength of the welded joint is 777 MPa, which is about 99% of the base metal, ensuring good strength. In general, metal is strengthened in four main ways: work hardening, solid solution strengthening, precipitation strengthening, and fine-grain strengthening. Texture, grain boundary, grain size, and fracture mode play an important role in the improvement of tensile properties for the present experimental magnetron welding process [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFrom the Hall-Petch formula, it can be concluded that grain refinement directly leads to an increase in grain boundary strengthening increments.\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:{\\Delta\\:}{\\sigma\\:}\\text{G}\\text{B}=\\text{K}\\text{y}\\sqrt{\\frac{1}{d}}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eΔσGB represents the increment in crystal boundary enhancement, Ky is the Hall-Petch coefficient, and d denotes the grain size. Substituting the average grain size into the formula reveals that the contribution rate of grain boundaries to strength is 5%, 30%, and 11% when the external magnetic field is set to 5A, 25A, and 35A, respectively. According to dislocation theory, a smaller grain size results in a higher number of grain boundaries within the same volume, which hinders dislocation slip. Consequently, finer grain sizes exhibit a more pronounced hindrance effect on dislocation slip, thereby enhancing the tensile strength of the structure. Notably, there is little variation in strength and elongation between excitation currents of 25A and 35A. This paper posits that the uneven grain size at an excitation current of 25A mitigates some of the benefits associated with fine grain strengthening.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e shows the orientation and quantity of \u0026lt;\u0026thinsp;100\u0026thinsp;\u0026gt;\u0026thinsp;grains are influenced by varying excitation currents and frequencies. It is believed that the {001}\u0026lt;100\u0026gt;-cube texture is unfavorable to the tensile strength, but the initial fiber texture (IFT) is favorable to the crystal slip, which can improve the tensile properties and anisotropy [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. For the without magnetic welding and the welding process with the addition of a weaker magnetic field, the volume of the molten pool is relatively small, and the columnar grains grow almost parallel to the \u0026lt;\u0026thinsp;100\u0026thinsp;\u0026gt;\u0026thinsp;direction due to the high solidification rate. And the heat is concentrated in the middle region and forms the temperature field direction which is highly consistent with the heat flow. Therefore, the {001}\u0026lt;100\u0026gt;-cube texture is mainly formed. For the strong magnetic field welding process, both the oscillating heat flux and the direction of the temperature field vary continuously. The formation of the {001}\u0026lt;100\u0026gt;-cube texture occurs only at a specific time, not during the entire solidification process [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Therefore, the {001}\u0026lt;100\u0026gt;-cube texture content of the sample is the lowest for the stronger magnetic field welding process, the tensile strength is high.\u003c/p\u003e \u003c/div\u003e"},{"header":"4 Conclusion","content":"\u003cp\u003eIn the welding process, an alternating cusp-shaped magnetic field used in TIG welding can significantly influence the arc shape, penetration, microstructure, and mechanical properties.\u003c/p\u003e \u003cp\u003e(1) When the alternating cusp-shaped magnetic field is applied, the arc can be significantly compressed or expanded compared to the absence of a magnetic field. The penetration depth increases, reaching a maximum value of 3.55 mm at a magnetic field strength of 25A and a frequency of 200Hz.\u003c/p\u003e \u003cp\u003e(2) Microscopic analysis results indicate that the application of the alternating cusp-shaped magnetic field can refine the grains, alter the maximum heat dissipation direction, and enhance the random distribution of grains. At a magnetic field strength of 25A and a frequency of 200Hz, the average grain size is reduced by approximately 41%, while the area of the grain boundary increases, resulting in the weakest preferred orientation of the grains.\u003c/p\u003e \u003cp\u003e(3) The improvement in tensile strength is explained in terms of texture and grain size reduction. It is posited that the {001}\u0026lt;100\u0026gt;-cube texture is detrimental to tensile strength. In the absence of a magnetic field and during the welding process with the addition of a weaker alternating cusp magnetic field, the {001}\u0026lt;100\u0026gt;-cube texture is predominantly formed. In contrast, during the strong alternating cusp-shaped magnetic field welding process, the temperature field direction is no longer aligned with the heat flow due to continuous oscillations affecting both parameters. Consequently, the formation of the {001}\u0026lt;100\u0026gt;-cube texture occurs only at specific times, leading to the lowest content of this texture in the samples.\u003c/p\u003e \u003cp\u003e(4) The application of the alternating cusp-shaped magnetic field can address the limitations of traditional TIG welding penetration and refine the grain structure, thereby facilitating the realization of efficient welding.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eThis work was supported by Natural Science Foundation Project of Chongqing Science and Technology Bureau of China (Grant No. cstc2021jcyj-msxmX0189).\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eThis work was supported by Natural Science Foundation Project of Chongqing Science and Technology Bureau of China (Grant No. cstc2021jcyj-msxmX0189).\u003c/p\u003e\n\u003cp\u003eConflicts of interest\u003c/p\u003e\n\u003cp\u003eWe declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled \u0026ldquo;Effects of Alternating Cusp-Shaped Magnetic Field on Penetration Behavior, Microstructure, and Mechanical Properties in TIG Welding\u0026rdquo;.\u003c/p\u003e\n\u003cp\u003eAvailability of data and material\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eCode availability\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003eAuthors\u0026apos; contributions\u003c/p\u003e\n\u003cp\u003eHuang and Luo carried out the experiment analysis and writing. Deng participated in the design of the experiment. Deng and Ma participated in the data validation.\u003c/p\u003e\n\u003cp\u003eEthics approval\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003eConsent to participate\u003c/p\u003e\n\u003cp\u003eWe declare that all authors consent to participate in the work in this paper.\u003c/p\u003e\n\u003cp\u003eConsent for publication\u003c/p\u003e\n\u003cp\u003eWe declare that all authors consent to publish the work and research results in this paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eJiang SY, Wang XW, Chen HM, Liu P. The impact of adscititious longitudinal magnetic field on CO\u003csub\u003e2 \u003c/sub\u003ewelding process, Adv Mater Res., 2012, 538-541: 1447\u0026ndash;1450.\u003c/li\u003e\n\u003cli\u003eChen Y, Sui FF, Cong KL, Yan XQ, Zhang GY, Guan SK. Effects of shielding gas and magnetic field on characteristics of AZ31 magnesium alloy by TIG welding. Mater Sci Forum, 2012, 704-705: 1186\u0026ndash;1196.\u003c/li\u003e\n\u003cli\u003eWu H, Chang YL, Lu L, Bai J. Review on magnetically controlled arc welding process. Int. J. Adv. Manuf. Technol., 2017, 91: 4263\u0026ndash;4273.\u003c/li\u003e\n\u003cli\u003eChang YL, Liu XL, Lu L, Babkin AS, Lee BY, Gao F. Impacts of external longitudinal magnetic field on arc plasma and droplet during short-circuit GMAW. Int. J. Adv. Manuf. Technol., 2014, 70: 1543\u0026ndash;1553.\u003c/li\u003e\n\u003cli\u003eNomura K, Ogino Y, Hirata Y. Shape control of TIG arc plasma by cusp-type magnetic field with permanent magnets. Weld Int., 2012, 26(10): 759\u0026ndash;764.\u003c/li\u003e\n\u003cli\u003eLiu S, Liu ZM, Zhao XC, Fan XG. Influence of cusp magnetic field configuration on K-TIG welding arc penetration behavior. Journal of Manufacturing Processes, 2014, 53: 229\u0026ndash;237.\u003c/li\u003e\n\u003cli\u003eBaskoro AS, Tuparjono, Erwanto, Frisman S, Yogi A, Winarto. Improvement of tungsten inert gas (TIG) welding penetration using the effect of electromagnetic field. Appl Mech Mater, 2014, 493: 558\u0026ndash;563.\u003c/li\u003e\n\u003cli\u003eWang J, Qingjie S, Jicai F, Wang S, Huanyao Z. Characteristics of welding and arc pressure in TIG narrow gap welding using novel magnetic arc oscillation. Int J Adv Manuf Technol, 2016, 86: 1\u0026ndash;8.\u003c/li\u003e\n\u003cli\u003eSun QJ, Wang J, Cai CW, Li Q, Feng JC. Optimization of magnetic arc oscillation system by using double magnetic pole to TIG narrow gap welding. Int J Adv Manuf Technol, 2016, 86: 761\u0026ndash;767.\u003c/li\u003e\n\u003cli\u003eCarroll BE, Palmer TA, Beese AM. Anisotropic tensile behavior of Ti\u0026ndash;6Al\u0026ndash;4V components fabricated with directed energy deposition additive manufacturing. Acta Mater, 2015, 87: 309\u0026ndash;320.\u003c/li\u003e\n\u003cli\u003eKok Y, Tan XP, Wang P, Nai MLS, Loh NH, Liu E, Tor SB. Anisotropy and heterogeneity of microstructure and mechanical properties in metal additive manufacturing: a critical review. Mater Design, 2018, 139: 565\u0026ndash;586.\u003c/li\u003e\n\u003cli\u003eKweon S, Raja DS. Comparison of anisotropy evolution in BCC and FCC metals using crystal plasticity and texture analysis. Eur. J. Mech. A-Solid, 2017, 62: 22\u0026ndash;38.\u003c/li\u003e\n\u003cli\u003eR\u0026ouml;ttger A, Geenen K, Windmann M, Binner F, Theisen W. Comparison of microstructure and mechanical properties of 316 L austenitic steel processed by selective laser melting with hot-isostatic pressed and cast material. Mater. Sci. Eng. A, 2016, 678: 365\u0026ndash;376.\u003c/li\u003e\n\u003cli\u003eGong MC, Meng YF, Zhang S, Zhang YZ, Zeng XY, Gao M. Laser-arc hybrid additive manufacturing of stainless steel with beam oscillation. Additive Manufacturing, 2020, 33: 101180.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Magnetic field, Arc shape, Penetration depth, Microstructure, Texture","lastPublishedDoi":"10.21203/rs.3.rs-8519968/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8519968/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigates the effects of an alternating cusp-shaped magnetic field on the penetration behavior, microstructure, and mechanical properties of TIG-welded 304 stainless steel. Experimental results demonstrate that the applied magnetic field dynamically alters arc morphology through Lorentz forces, cyclically compressing or expanding the arc. This alteration leads to a reduced effective arc area on the workpiece, significantly enhancing penetration depth. At optimal parameters (25A excitation current, 200Hz frequency), the penetration depth increased to 3.55 mm, doubling compared to non-magnetic welding. Microstructural analysis revealed substantial grain refinement, with an average grain size reduction of 41% under the 25A magnetic field, alongside a weakened {001}\u0026lt;100\u0026gt;-cube texture, where the maximum pole density decreased from 8.10 to 3.13. The suppression of this texture, which is detrimental to tensile strength, is attributed to disrupted heat flow alignment and continuous oscillation-induced variations in the temperature field during solidification. Consequently, the tensile strength of welded joint improved to 777 MPa (99% of the base metal), primarily due to grain boundary strengthening and randomized grain orientation. These findings highlight the alternating cusp-shaped magnetic field as an effective method to enhance TIG welding efficiency by optimizing penetration and microstructure, providing insights into texture control and mechanical property enhancement in welded joints.\u003c/p\u003e","manuscriptTitle":"Effects of Alternating Cusp-Shaped Magnetic Field on Penetration Behavior, Microstructure, and Mechanical Properties in TIG Welding","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-22 19:37:40","doi":"10.21203/rs.3.rs-8519968/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2d0b4eb3-93d1-4eea-9a25-f6909385be05","owner":[],"postedDate":"January 22nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-15T16:16:15+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-22 19:37:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8519968","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8519968","identity":"rs-8519968","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}