焊接方法对C24S铝锂合金组织和性能的影响

Effect of different welding method on the microstructure and mechanical properties of C24S Al-Li alloy

对2 mm C24S铝锂合金薄板进行TIG焊和FSW焊接试验,焊后利用光学显微镜(OM)和扫描电镜(SEM)观察分析两种焊接方法所得接头的显微组织,并测试其室温拉伸性能和显微硬度。结果表明:TIG焊所得接头组织粗大,焊缝气孔缺陷严重,焊缝区强化相大量溶解,接头抗拉强度仅为母材的47.9%,焊缝显微硬度为92 HV,且拉伸接头塑性较差;FSW焊焊缝成形良好,接头组织细小,且焊缝强化相并未溶解,接头拉伸强度达到母材的82.6%,焊缝显微硬度高达115 HV,接头塑性良好。

C24S Al-Li plates with 2 mm thickness were successfully joined by FSW and TIG welding methods. The microstructure and fracture morphology of welding joints with the two welding methods were observed and analyzed by optical microscopy and scanning electron microscopy,the room temperature tensile properties and micro-hardness were also tested. The results show that TIG welding joint is composed of coarse microstructure,the serious porosity defects and the dissolution of strengthening phases in the weld zone all lead to the decrease of mechanical properties and plasticity, the tensile strength of joint is only 47.9% of the base metal and the micro- hardness is 92 HV. The welding joint with FSW welding has good formation and small microstructure,the strengthening phase does not dissolve,which leads to the tensile strength of weld joint reach 82.6% of the base metal and micro-hardness is up to 115 HV,and the joint exhibits good plasticity.