Abstract：The friction stir welding stirring head structure and welding process parameters lead to different welding heat inputs and material flow behaviors that result in different types of weld defects. This study simulated friction stir welding of A7N01 material using the Deform software. The model was verified by comparing with measured temperatures and observed defects in welding tests. The model was then used to investigate the influence of three kinds of stirring heads on the weld defect formation. The material particle tangential filling speeds varied with depth for different stiring heads. The circular stirring head mostly created tunnel-type and furrow-type defects, while the plane stirring heads mostly caused half-tunnel-and-half-furrow-type defects. Different process parameters for the same stirring head resulted in different types of defects in the advancing side of the weld. A two-dimensional process parameter selection window was then developed to select conditions that would prevent typical welding defects for each stirring head. The process parameter range is wider for the plane stirring head than for the circular stirring head for friction stir welding.
杨智勇, 李武鹏, 张宇, 李志强, 李卫京. 搅拌头结构对搅拌摩擦焊缺陷形成机制的影响[J]. 清华大学学报（自然科学版）, 2022, 62(2): 374-384.
YANG Zhiyong, LI Wupeng, ZHANG Yu, LI Zhiqiang, LI Weijing. Influence of stirring head structure on the defect formation mechanism in friction stir welding. Journal of Tsinghua University(Science and Technology), 2022, 62(2): 374-384.
[1] KIM Y G, FUJⅡ H, TSUMURA T, et al. Three defect types in friction stir welding of aluminum die casting alloy[J]. Materials Science and Engineering:A, 2006, 415(1-2):250-254. [2] ARBEGAST W J. A flow-partitioned deformation zone model for defect formation during friction stir welding[J]. Scripta Materialia, 2008, 58(5):372-376. [3] AL-BADOUR F, MERAH N, SHUAIB A, et al. Coupled Eulerian Lagrangian finite element modeling of friction stir welding processes[J]. Journal of Materials Processing Technology, 2013, 213(8):1433-1439. [4] DEHGHANI M, AMADEH A, MOUSAVI S A A A. Investigations on the effects of friction stir welding parameters on intermetallic and defect formation in joining aluminum alloy to mild steel[J]. Materials & Design, 2013, 49:433-441. [5] CHEN H B, YAN K, LIN T, et al. The investigation of typical welding defects for 5456 aluminum alloy friction stir welds[J]. Materials Science and Engineering:A, 2006, 433(1-2):64-69. [6] BHATTACHARYAT K, DAS H, JANA S S, et al. Numerical and experimental investigation of thermal history, material flow and mechanical properties of friction stir welded aluminium alloy to DHP copper dissimilar joint[J]. The International Journal of Advanced Manufacturing Technology, 2017, 88(1-4):847-861. [7] AKBARI M, ASADI P, BEHNAGH R A. Modeling of material flow in dissimilar friction stir lap welding of aluminum and brass using coupled Eulerian and Lagrangian method[J]. The International Journal of Advanced Manufacturing Technology, 2021, 113(3-4):721-734. [8] LI J Z, ZHAO H X, LUAN G H. 3D numerical simulation of physical fields of friction stir welding for aluminum alloy[J]. Transactions of the China Welding Institution, 2016, 37(5):15-18. (in Chinese)李继忠, 赵华夏, 栾国红. 铝合金搅拌摩擦焊物理场三维数值模拟[J]. 焊接学报, 2016, 37(5):15-18. [9] MAHTO R P, KUMAR R, PAL S K. Characterizations of weld defects, intermetallic compounds and mechanical properties of friction stir lap welded dissimilar alloys[J]. Materials Characterization, 2020, 160:110115. [10] NI Y, FU L, SHEN Z, et al. Role of tool design on thermal cycling and mechanical properties of a high-speed micro friction stir welded 7075-T6 aluminum alloy[J]. Journal of Manufacturing Processes, 2019, 48:145-153. [11] SADOUNA M, WAGIH A, FATHY A, et al. Effect of tool pin side area ratio on temperature distribution in friction stir welding[J]. Results in Physics, 2019, 15:102814. [12] BAYAZID S M, FARHANGI H, GHAHRAMANI A. Effect of pin profile on defects of friction stir welded 7075 aluminum alloy[J]. Procedia Materials Science, 2015, 11:12-16. [13] ZHAO Y X, HAN J M, DOMBLESKY J P, et al. Investigation of void formation in friction stir welding of 7N01 aluminum alloy[J]. Journal of Manufacturing Processes, 2019, 37:139-149. [14] KUMAR K, KAILAS S V. The role of friction stir welding tool on material flow and weld formation[J]. Materials Science and Engineering:A, 2008, 485(1-2):367-374. [15] COLLIGAN K. Material flow behavior during friction stir welding of aluminum[J]. Welding Journal, 1999, 78(7):229-237. [16] MORISADA Y, FUJⅡ H, KAWAHITO Y, et al. Three-dimensional visualization of material flow during friction stir welding by two pairs of X-ray transmission systems[J]. Scripta Materialia, 2011, 65(12):1085-1088. [17] TIAN W H, SU H, WU C S. Effect of ultrasonic vibration on thermal and material flow behavior, microstructure and mechanical properties of friction stir welded Al/Cu joints[J]. The International Journal of Advanced Manufacturing Technology, 2020, 107(1-2):59-71. [18] TUTUNCHILAR S, HAGHPANAHI M, GIVI M K B, et al. Simulation of material flow in friction stir processing of a cast Al-Si alloy[J]. Materials & Design, 2012, 40:415-426. [19] SHI Q Y, WANG X B, KANG X, et al. Temperature fields during friction stir welding[J]. Journal of Tsinghua University (Science & Technology), 2010, 50(7):980-983, 988. (in Chinese)史清宇, 王细波, 康旭, 等. 搅拌摩擦焊温度场[J]. 清华大学学报(自然科学版), 2010, 50(7):980-983, 988. [20] SHEPPARD T, JACKSON A. Constitutive equations for use in prediction of flow stress during extrusion of aluminium alloys[J]. Materials Science and Technology, 1997, 13(3):203-209. [21] TANG J M, SHEN Y F. Numerical simulation and experimental investigation of friction stir lap welding between aluminum alloys AA2024 and AA7075[J]. Journal of Alloys and Compounds, 2016, 666:493-500. [22] WAN Z Y, ZHANG Z, ZHOU X. Finite element modeling of grain growth by point tracking method in friction stir welding of AA6082-T6[J]. The International Journal of Advanced Manufacturing Technology, 2017, 90(9-12):3567-3574. [23] SUN Z, WU C S. A numerical model of pin thread effect on material flow and heat generation in shear layer during friction stir welding[J]. Journal of Manufacturing Processes, 2018, 36:10-21. [24] WANG Y L. Study on the design of multi-flat FSW tool and its effect on joint structure and properties[D]. Beijing:Beijing Jiaotong University, 2020. (in Chinese)汪玉琳. 多平面搅拌头设计及其对接头组织性能的影响研究[D]. 北京:北京交通大学, 2020.
2022, Vol. 62 
