焊后涂装工艺对6063-T6铝合金MIG焊T型接头组织和性能的影响

采用金属熔化极惰性气体保护(MIG)焊制备6063-T6铝合金T型接头,之后对T型接头进行涂装,研究了焊后涂装工艺对接头组织与性能的影响。结果表明:涂装工艺对接头各区域晶粒形态和尺寸没有影响,涂装后热影响区中针状β″相析出量明显增加;焊后涂装可以显著提高接头的力学性能,抗拉强度较涂装前的提高了13%,热影响区的显微硬度较涂装前的提高了18.8%;涂装完成前,接头最薄弱区域为热影响区,而涂装完成后,最薄弱区域为焊缝处;涂装后镁、硅原子在热影响区富集形成溶质原子富集区(GP区),同时针状β″相析出量的增加干扰位错运动,导致热影响区的硬度大幅提高,而使焊缝处成为接头的最薄弱区域。

Effect of Post-Weld Coating Process on Microstructure and Properties of 6063-T6 Aluminum Alloy MIG Welded T-Joint

T-joint of 6063-T6 aluminum alloy was prepared by metal inert gas(MIG)welding and then coated.The influence of the post-weld coating process on the structure and properties of the joint was studied.The results show that the coating process had no effect on the grain morphology and size of each region of the joint.The amount of acicularβ″phase precipitation in heat affected zone increased significantly after coating.The mechanical properties of the joint were significantly improved after post-weld coating;the tensile strength was 13%higher than that before coating;the microhardness of the heat-affected zone was 18.8%higher than that before coating.The weakest area of the joint was the heat affected zone before coating,and was the weld zone after coating.Magnesium and silicon atoms were enriched in the heat affected zone to form a solute atoms-rich zone,the GP(Guinier&Preston)zone;meanwhile,the increase of acicularβ″phase precipitation disturbed the movement of dislocations,resulting in the significant increase of the hardness of the heat affected zone,and making the weld seam the weakest area of the joint.