Mechanical Property Improvement in Dissimilar Friction Stir Welded Al5083/Al6061 Joints: Effects of Post-Weld Heat Treatment and Abnormal Grain Growth

Abstract

The 5083 and 6061(T6) aluminum (Al) alloys are widely used in transportation industries and the development of structural designs because of their high toughness and high corrosion resistance. Friction stir welding (FSW) was performed to produce the dissimilar welded joint of Al5083-Al 6061(T6) under different welding parameters. However, softening behavior occurred in the friction stir welded (FSWed) samples because of grain coarsening or the dissolution of precipitation-hardening phases in the welding zone. Consequently, this research intended to investigate the effect of the post-weld heat treatment (PWHT) method on the mechanical property improvement of the dissimilar FSWed Al5083-Al6061(T6) and governing abnormal grain growth (AGG) through different welding parameters. The results showed PWHT enhanced the mechanical properties of dissimilar joints of Al5083-Al6061(T6). AGG was obtained in the microstructure of PWHTed joints, but appropriate PWHT could recover the dissolved precipitation-hardening particle in the heat-affected zone of the as-welded joint. Further, the tensile strength of the dissimilar joint increased from 181 MPa in the as-welded joint to 270 MPa in the PWHTed joint, showing 93% welding efficacy.

Effect of the Anodizing Temperature on Microstructure and Tribological Properties of 6061 Aluminum Alloy Anodic Oxide Films

“…Aluminum is the most abundant metallic element in the earth's crust. The low density, high specific strength, excellent thermal conductivity, and corrosion resistance of aluminum and its alloys (Al-Cu, Al-Mg, Al-Mg-Si and Al-Zn) are promoting the development of aerospace, construction, automobile, shipbuilding, controllable fusion technology and chemical industries [1][2][3][4]. The Mg and Si elements in 6061 aluminum alloy (Al-Mg-Si) improve the plasticity, weldability, and processability of the material, making the 6061 aluminum alloy widely used in electrical fixtures and electronic precision instruments, aerospace, and automotive structural parts [5][6][7].…”

The Evolution of Abnormal Grains during the Heating Stage of a Post-Weld Solution Treatment in a Friction-Stir-Welded 2519 Aluminium Alloy

“…This has frequently been seen to lead to abnormal grain growth (AGG) in the stir zone, a phenomenon involving a significant coarsening of some grains, which tend to consume a considerable portion of the microstructure . This undesirable phenomenon has been reported for almost all heat-treatable aluminium alloys, including the 2xxx [7][8][9][10][11][12][13][14][15][16], 6xxx [17][18][19][20][21][22], and 7xxx [11,[24][25][26][27][28][29][30][31][32] series as well as their dissimilar combinations [30][31][32][33][34][35][36][37] that show similar characteristics.…”

Improvement of Mechanical Behavior of FSW Dissimilar Aluminum Alloys by Postweld Heat Treatments

“…Furthermore, according to their observations, the primary particles frequently generated in the SZ of AA7475 were MgZn2, Al2Cu, and Al2CuMg. Under various welding conditions, creation of the dissimilar welded junction of Al5083-Al 6061(T6) was done; however, due to the dissolution of precipitation-hardening segments in the weld zone as well as the impact of the postweld heat treatment technique on the improvement of the mechanical properties of the dissimilar welded Al5083-Al6061 and leading abnormal grain evolution through various factors, softening behavior developed in the weld samples [14]. Baghdadi et al directed to enhance the mechanical characteristics of Al-Mg-Si alloy through postweld heat treatment, the potential for regulating aberrant grain growth by adjusting welding conditions.…”