Abstract: Laser welding and solution treatment faging were performed on A286 alloy sheet. The effects of laser welding and solution treatment+aging on the microstructure and high temperature durability of welded joint were studied. The results show that the durability of the A286 alloy at 500 ℃ follows the superiority order of laser welding+solution treatment+aging, base material, and laser welding. The specimens of the A286 alloy base metal, laser welding part and laser welding+solution and aging part shows no obvious grain elongation and obvious persistent creep. The weld of the laser welding part has obvious dendrite structure, the heat affected zone is equiaxed crystal structure, and the transition zone between the weld and the heat affected zone is narrow, which makes the weld and the heat affected zone become the weak area of durability. Solution treatment and aging can reduce segregation, eliminate residual stress, and widen the transition zone between weld and heat affected zone. The frcture of the laser welded joint durability specimen has shallow dimples and cleavage surface, while the fracture of the laser welded and solution treated+aged specimen is uniform and fine, showing the characteristics of microporous aggregation. In order to improve the high temperature durability of laser welded part, solid solution and aging treatment should be carried out after laser welding to improve the structure of welded joints.

Key words: A286 alloy, laser welding, solution and aging, high temperature durability, microstructure