Effect of Post-Weld Heat Treatment on Microstructure and Properties of Al-Mg Alloy Welded Joints

The 5083 aluminum alloy sheet was welded by metal inert gas welding with zirconium-containing Al-Mg alloy welding wire as filling material. Then the post-weld heat treatment was carried out at 130 degrees C for 3 hours and 320 degrees C for 1 hour, respectively. The results show that the effects of two annealing treatments on the MIG-welded Al-Mg joints are basically equivalent. After heat treatment, a large number of Al3Zr particles are precipitated in the weld zone of joints. These particles are coordinated with the matrix, which greatly improves the mechanical properties of the joint. The tensile strength, yield strength and elongation of the joints are increased by about 40MPa, 25MPa and 4.5%, compared with that of the joints without heat treatment. However, the intergranular corrosion resistance of the joint held at 320 degrees C for 1 hour is better than that of the welded joint held at 130 degrees C for 3 hours.