At present, magnesium alloys are extensively used in numerous applications due to their light weight and better characteristics. Welding of magnesium alloys is regarded as one of the most complex phenomena in various industries. The friction stir welding of magnesium alloys has encouraged abundant scientific and industrial interest as it has the potency to form a good quality joint. Post welding heat treatment is an appropriate process to further improve the properties or performance of FSW joints. Therefore, the present work aims to join AZ31 Mg alloy plates by friction stir welding, and microstructural and mechanical properties of the joint have been examined. Furthermore, the consequence of post welding heat treatment on the microstructure and mechanical properties of FSW joint has been evaluated. Tensile strength and elongation of FSW joint were about 145.4 ± 4.9 MPa and 9.5 ± 0.9%, respectively. It was found that post welding heat treatment was beneficial in homogenizing grains and to enhance mechanical properties. Tensile strength and elongation of the joint were improved by 4.74% and 15.78% respectively after PWHT. The highest microhardness of stir zone decreased about 6.84% (73 Hv to 68 Hv) after heat treatment and hardness pattern of weld became relatively smooth. Toughness of PWHT joint was 4.5 ± 0.17 Joules. The mode of tensile failure of as-welded and PWHT joint was ductile.

目前，镁合金由于其重量轻和性能更好而被广泛用于许多应用中。镁合金的焊接被认为是各个行业中最复杂的现象之一。镁合金的搅拌摩擦焊具有形成优质接头的潜力，因此激发了广泛的科学和工业兴趣。焊后热处理是进一步改善FSW接头的性能或性能的合适方法。因此，目前的工作旨在通过摩擦搅拌焊接来连接AZ31 Mg合金板，并研究了该接头的组织和力学性能。此外，已经评估了焊后热处理对FSW接头的组织和力学性能的影响。FSW接头的拉伸强度和伸长率分别约为145.4±4.9 MPa和9.5±0.9％。已经发现，焊接后热处理有利于使晶粒均质化并增强机械性能。PWHT后，关节的抗张强度和伸长率分别提高了4.74％和15.78％。热处理后，搅拌区的最高显微硬度降低了约6.84％（73 Hv至68 Hv），并且焊缝的硬度模式变得相对平滑。PWHT接头的韧性为4.5±0.17焦耳。焊接和PWHT接头的拉伸破坏方式是延性的。PWHT后分别达到78％。热处理后，搅拌区的最高显微硬度降低了约6.84％（73 Hv至68 Hv），并且焊缝的硬度模式变得相对平滑。PWHT接头的韧性为4.5±0.17焦耳。焊接和PWHT接头的拉伸破坏方式是延性的。PWHT后分别达到78％。热处理后，搅拌区的最高显微硬度降低了约6.84％（73 Hv至68 Hv），并且焊缝的硬度模式变得相对平滑。PWHT接头的韧性为4.5±0.17焦耳。焊接和PWHT接头的拉伸破坏方式是延性的。