5A90铝锂合金激光焊焊缝微观组织特征  

Microstructure investigation of Nd:YAG laser welded 5A90 aluminium-lithium alloys

作　　者：崔丽[1] 李晓延[1] 贺定勇[1] 陈俐[2] 巩水利[2] 

机构地区：[1]北京工业大学材料学院,北京100124 [2]北京航空制造工程研究所高能束流加工技术研究室,北京100024

出　　处：《焊接学报》2010年第9期77-80,84,共5页Transactions of The China Welding Institution

基　　金：航空科学基金资助项目(20085475003);重点实验室基金资助项目(9140C4051030802)

摘　　要：采用Nd:YAG激光焊进行了5A90铝锂合金薄板的对接试验,测试了接头横截面不同位置沿水平方向的显微硬度.利用光学显微镜、扫描电镜(SEM)和透射电镜(TEM)分析了焊缝金属不同位置的显微组织变化.结果表明,焊缝区不同位置的显微硬度低于母材;焊缝熔合线附近出现了等轴晶粒细晶区(EQZ);5A90合金主要的析出强化相是δ’相,在焊缝金属不同位置都有LI2超点阵衍射斑点的出现,证实焊缝中有δ’相析出,但数量很少,这解释了焊缝显微硬度降低的原因.Nd:YAG laser welding of 5A90 aluminium-lithium(Al-Li) alloy thin sheets has been carried out.Microhardness tests across the transverse section of the weld were performed.The influence of laser welding on the microstructure of 5A90 aluminium-lithium alloy at different sections has been evaluated by optical microscope,SEM and TEM.Microhardness tests revealed that the laser weld had lower microhardness than that of base metal.Laser welds revealed the formation and presence of a zone of equiaxed grains (EQZ) along the fusion boundary.The major strengthening phase in 5A90 aluminium-lithium alloy was δ' phase particles.The presence of the δ' precipitates in the welds was proved by the LI2 superlattice reflections in diffraction patterns,but the volume of the δ' precipitates in the weld zone was very little,which attributed to the decrease in the microhardness of the weld compared with the base metal.

关 键 词：铝锂合金 激光焊 显微组织 析出相 

分 类 号：TG456.7[金属学及工艺—焊接]