不同热处理状态2219铝合金TIG焊接头组织性能分析

Microstructure and property of TIG welded 2219 aluminum alloy by different heat treatment

采用"直流氦弧打底+交流氩弧盖面"的两层TIG自动焊进行了2219CYS与2219C10S的焊接,分析了不同热处理状态焊接接头的组织及成分,进行了接头常温及低温(-196℃)拉伸试验及断裂行为研究.结果表明,2219C10S和2219CYS母材组织均为α(Al)基体上分布着Al2Cu强化相,但母材显微组织形态存在较大差异.焊缝和部分熔化区晶界上分布着条网状α+θ共晶,内部为颗粒状α+θ共晶,固溶到基体中的Cu元素含量分布不均匀.接头断裂起源于CYS侧紧邻打底焊熔合线的部分熔化区,之所以在CYS侧启裂与母材强度、晶粒尺度、晶粒取向及晶界偏析有关.

Two heat-treated 2219 aluminum alloys were welded by two-pass TIG welding. DC TIG was used for first pass,AC TIG for cover pass. The micro-structure,phase composition and mechanical properties under room and cryogenictemperaturesof welded joint were tested. The results show that the micro-structures of base metals are α( Al) with Al2 Cu strengthening phase,while 2219 C10 S has a lath-like micro-structure along the rolling direction,2219 CYS has a coarse irregular polygon micro-structure. α + θ eutectic phases distribute on grain boundary and matrix in weld and partial meltedzone. Solid solution of Cu in the matrix is in-homogeneous. Coarse grain,grain orientation and grain boundary segregation could be the causes of fracture initiation from partial melted zone of 2219 CYS.