Microstructure Evolution and Mechanical Properties of 6061/7075 Al Alloy Stir-friction Welded Joint

TANG Zhengwei; SHENG Yijia; ZHANG Yu; ZHOU Dongshuai; WANG Jian; BAI Zhihao

doi:10.3969/j.issn.1674-6457.2026.09.009

PDF(30523 KB)

Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (9) : 80-89. DOI: 10.3969/j.issn.1674-6457.2026.09.009

Advanced Joining Technology

Microstructure Evolution and Mechanical Properties of 6061/7075 Al Alloy Stir-friction Welded Joint

TANG Zhengwei, SHENG Yijia, ZHANG Yu, ZHOU Dongshuai, WANG Jian, BAI Zhihao^*

Author information +

History +

Abstract

The work aims to investigate the effects of tool rotation speed (750-1 550 r/min) on the microstructural evolution and mechanical properties of stir-friction welded joints of 6061-T6/7075-T6 dissimilar aluminum alloys. The FSW-LM-BM16 welding machine was used at a fixed feed rate of 80 mm/min and a plunge depth of 4.9 mm. Five sets of process parameters (750, 950, 1 150, 1 350, 1 550 r/min) were designed. Microstructural analysis was conducted through metallographic microscopy and backscatter electron diffraction to examine grain size, grain boundary distribution, and texture evolution in the welding zone (NZ), heat-machined zone (TMAZ), and heat-affected zone (HAZ). Hardness distribution and tensile strength were measured with a Vickers hardness tester and a tensile testing machine, respectively. Fracture morphology was observed by scanning electron microscopy (SEM). At a rotation speed of 1 350 r/min, the heat and mechanical inputs achieved optimal equilibrium, resulting in a regular “onion ring” structure without defects. The highest tensile strength of the joint reached 278.75 MPa (91.4% of the base material strength of 6061-T6). Dynamic recrystallization in the NZ zone was complete, with grain refinement to an average size of 23.04 μm² and the proportion of large-angle grain boundaries increasing to 59.9%. The texture transitioned from the copper-type {112}<111> and brass-type {110}<112> of the base material to the recrystallized cubic texture {001}<110> in the HAZ zone. The hardness distribution exhibited a “W”-shaped asymmetry, with the lowest point located in the AS-HAZ (approximately 65 HV). The optimum process parameters are 1 350 r/min, the thermomechanical coupling effect promotes grain refinement and texture transformation, and the joint strength is significantly improved. The softening of AS-HAZ is the fracture dominant region, and the small size of the fracture dimple proves the plasticity decline.

Key words

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

TANG Zhengwei, SHENG Yijia, ZHANG Yu, ZHOU Dongshuai, WANG Jian, BAI Zhihao. Microstructure Evolution and Mechanical Properties of 6061/7075 Al Alloy Stir-friction Welded Joint[J]. Journal of Netshape Forming Engineering. 2026, 18(9): 80-89 https://doi.org/10.3969/j.issn.1674-6457.2026.09.009

References

[1] WANG Y Q, HUANG R, SHENG Y J, et al.Influence of Heat Input on Microstructure and Mechanical Properties of AA2A12 and AA7075 FSW Joints with Their Temperature Field Model[J]. Transactions of the Indian Institute of Metals, 2026, 79(3): 38.
[2] 邓清洪, 刘晓东, 杨升平. 6005-T6铝合金静止轴肩搅拌摩擦焊工艺研究[J]. 电焊机, 2025, 55(8): 47-52.
DENG Q H, LIU X D, YANG S P.Researched on the Process of Stationary Shoulder Friction Stir Welding of 6005-T6 Aluminum Alloy[J]. Electric Welding Machine, 2025, 55(8): 47-52.
[3] 张亚, 赵云峰, 戴忠晨, 等. 6061-T6铝合金静止轴肩搅拌摩擦焊角接接头焊接工艺研究[J]. 电焊机, 2025, 55(4): 64-72.
ZHANG Y, ZHAO Y F, DAI Z C, et al.Research on the Welding Process of Corner Joint of 6061-T6 Aluminum Alloy with Stationary Shoulder Friction Stir Welding[J]. Electric Welding Machine, 2025, 55(4): 64-72.
[4] 张香云, 刘通, 耿家源. 7075铝合金搅拌摩擦焊工艺及性能研究[J]. 特种铸造及有色合金, 2024, 44(8): 1114-1118.
ZHANG X Y, LIU T, GENG J Y.Process and Performance of 7075 Aluminum Alloy Friction Stir Welding[J]. Special Casting & Nonferrous Alloys, 2024, 44(8): 1114-1118.
[5] 曲来鹏, 马宁, 肖笑, 等. 6061铝合金搅拌摩擦焊曲线接头的组织与性能[J]. 材料热处理学报, 2023, 44(12): 176-184.
QU L P, MA N, XIAO X, et al.Microstructure and Properties of 6061 Aluminum Alloy Friction Stir Welding Curved Joints[J]. Transactions of Materials and Heat Treatment, 2023, 44(12): 176-184.
[6] 庞秋, 詹博异. 7075铝合金高速搅拌摩擦焊材料流动行为及性能研究[J]. 精密成形工程, 2023, 15(3): 72-80.
PANG Q, ZHAN B Y.Material Flow Behaviors and Properties of 7075 Aluminum Alloy under High Speed Friction Stir Welding[J]. Journal of Netshape Forming Engineering, 2023, 15(3): 72-80.
[7] 朱海, 张峰, 张剑, 等. 7075-T6铝合金无减薄搅拌摩擦焊接头组织与性能研究[J/OL]. 兵器材料科学与工程, 1-11[2026-01-09]. https://doi.org/10.14024/j.cnki.1004-244x.20250922.001.
ZHU H, ZHANG F, ZHANG J, et al. Study on Microstructure and Properties of7075-T6 Aluminum Alloy Welded Joint Without Reduction by Stir-Friction Welding[J/OL]. Materials Science and Engineering of Ordnance, 1-11 [2026-01-09]. https://doi.org/10.14024/j.cnki.1004-244x.20250922.001.
[8] 王立刚, 刘莹, 王复栋, 等. 搅拌速度对6082/AZ31合金搅拌摩擦焊焊接接头力学性能的影响[J]. 焊接技术, 2026, 55(7): 48-52.
WANG L G, LIU Y, WANG F D, et al.Effect of Stirring Speed on the Mechanical Properties of Friction Stir Welded Joints of 6082/AZ31 Alloys[J]. Welding Technology, 2026, 55(7): 48-52.
[9] 黄相山, 孟宇驰, 赵岩, 等. 新能源电池托盘用5083/6061异种铝合金搅拌摩擦焊接工艺研究[J]. 精密成形工程, 2025, 17(9): 103-114.
HUANG X S, MENG Y C, ZHAO Y, et al.Friction Stir Welding Process of 5083/6061 Dissimilar Aluminum Alloys for New Energy Battery Trays[J]. Journal of Netshape Forming Engineering, 2025, 17(9): 103-114.
[10] 王建洲. 6061-T6 Al/ZK61M Mg异材搅拌摩擦焊机理及双道次工艺研究[D]. 大连: 大连交通大学, 2025.
WANG J Z.Study on the Friction Welding Mechanism and Two-pass Process of 6061-T6 Al/ZK61M Mg Alloy [D]. Dalian: Dalian Jiaotong University, 2025.
[11] 吴璇, 王鹏, 钱志杰, 等. 异种铝合金搅拌摩擦焊显微组织与性能研究[J]. 兵器材料科学与工程, 2025, 48(6): 53-57.
WU X, WANG P, QIAN Z J, et al.Study on Microstructure and Properties of Dissimilar Aluminum Alloy Friction Stir Welding[J]. Ordnance Material Science and Engineering, 2025, 48(6): 53-57.
[12] 田洋, 张元好. 异种铝合金搅拌摩擦焊工艺研究[J]. 特种铸造及有色合金, 2024, 44(2): 216-222.
TIAN Y, ZHANG Y H.Friction Stir Welding Process of Dissimilar Aluminum Alloys[J]. Special Casting & Nonferrous Alloys, 2024, 44(2): 216-222.
[13] 王钟德, 王瑞杰, 刘国寿, 等. 7075/2A12异种铝合金搅拌摩擦焊搭接接头疲劳寿命预测研究[J]. 现代制造工程, 2023(10): 135-144.
WANG Z D, WANG R J, LIU G S, et al. Fatigue Life Prediction of7075/2A12 Dissimilar Aluminum Alloys Friction Stir Welding Lap Joints[J]. Modern Manufacturing Engineering, 2023(10): 135-144.
[14] 刘晓超, 王江华. 搅拌头转速对6061和7075异种铝合金搅拌摩擦焊接头性能的影响[J]. 宇航材料工艺, 2022, 52(5): 90-95.
LIU X C, WANG J H.Effect of Stirring Head’s Totation Speed on Properties of 6061 and 7075 Dissimilar Aluminum Alloy FSW Joints[J]. Aerospace Materials & Technology, 2022, 52(5): 90-95.
[15] WANG Y Q, BAI Z H, WANG P Y, et al.Study of Anisotropy Impact of 2A12 and 7075 Dissimilar Aluminum Alloys FSW Joints[J]. Vacuum, 2025, 236: 114173.
[16] HAN B, HUANG Y X, LV S X, et al.AA7075 Bit for Repairing AA2219 Keyhole by Filling Friction Stir Welding[J]. Materials & Design, 2013, 51: 25-33.
[17] 付宁宁, 孟宪伟, 曹兴华, 等. 搅拌摩擦焊接头“洋葱环”层状结构形成机制探索[J]. 焊接, 2016(2): 28-31.
FU N N, MENG X W, CAO X H, et al.Formation of Onion Rings in Friction Stir Welded Joint[J]. Welding & Joining, 2016(2): 28-31.
[18] 邓舒浩, 邓运来, 张臻, 等. 焊接工艺对6082-T6铝合金FSW接头微观组织与力学性能的影响[J]. 中南大学学报(自然科学版), 2018, 49(10): 2413-2422.
DENG S H, DENG Y L, ZHANG Z, et al.Effect of Welding Parameters on Microstructure and Mechanical Properties of 6082-T6 Aluminum Alloy FSW Joint[J]. Journal of Central South University (Science and Technology), 2018, 49(10): 2413-2422.
[19] ZHANG Y, LIU G C, SUN P.Effect of Friction- Stir-Welding Parameters on the Welding Microstructure and Properties of 5083 and 7075 Aluminum Alloys[J]. Materiali in Tehnologije, 2025, 59(3): 461-468.
[20] YANG H F, HUANG R S, ZHANG Y L, et al.Effect of Rolling Deformation and Passes on Microstructure and Mechanical Properties of 7075 Aluminum Alloy[J]. Ceramics International, 2023, 49(1): 1165-1177.
[21] 李波. 预变形对7075铝合金时效成形微观组织及力学性能的影响[D]. 南昌: 南昌航空大学, 2017.
LI B.Effect of Pre-deformation on Microstructure and Mechanical Properties of 7075 Aluminum Alloy during Aging Forming[D]. Nanchang: Nanchang Hangkong University, 2017.
[22] HUMPHREYS F J.Recrystallization Mechanisms in Two-Phase Alloys[J]. Metal Science, 1979, 13(3/4): 136-145.
[23] 李惠曲, 邢清源, 张景亮, 等. 固溶工艺对7075铝合金薄板组织与损伤容限性能的影响[J]. 机械工程材料, 2025, 49(5): 91-97.
LI H Q, XING Q Y, ZHANG J L, et al.Effect of Solution Process on Microstructure and Damage Tolerance Properties of 7075 Aluminum Alloy Sheet[J]. Materials for Mechanical Engineering, 2025, 49(5): 91-97.
[24] ENGLER O, ZAEFFERER S, RANDLE V.Introduction to Texture Analysis: Macrotexture, Microtexture, and Orientation Mapping[M]. 3rd Ed. Boca Raton: CRC Press, 2023.
[25] CALLISTER W D Jr, RETHWISCH D G. Materials Science and Engineering: An Introduction[M]. 8th ed. John Wiley & Sons, 2020.