铝锂合金激光填丝焊接接头组织性能研究

利用激光填丝焊接方法对5A90铝锂合金薄板焊接头的组织性能进行了研究。结果表明:激光填丝焊接头的主要组织特征为细晶层和焊缝区大范围等轴晶,与激光焊接头类似,而不同之处表现为激光填丝焊接头的显微组织相对细化,柱状晶区范围相对减小。激光填丝焊缝区硬度HV0.2(925.7MPa)略低于激光焊缝区硬度(956.5MPa),但前者硬度分布更加均匀。激光填丝焊接头的抗拉强度稍低于激光焊接头,分别达母材的79.22%和73.03%,但其断后延伸率却显著高于后者,分别达母材的38.65%和20.38%。综上所述,5A90铝锂合金激光填丝焊接头的组织性能略优于激光焊接头,若使激光填丝焊接头的综合力学性能达到使用要求,不仅需要焊后热处理强化,还需要与母材匹配性更好的焊丝。

Microstructure and Mechanical Properties of Al-Li Alloy by Laser Welding with Filler Wire

The microstructure and mechanical properties of 5A90 Al-Li alloy sheet joint by laser welding with filler wire (LWFW) have been studied. The results indicate that the major microstructure characteristics of the joint by LWFW are fine-grained layer and equiaxed grains in most of the welded seam, which are also the major characteristics of the joint by laser beam welding (LBW). However, compared with the joint by LBW, the microstructure of the joint by LWFW is finer, and the range of the columnar crystals zone is prone to decrease. The microhardness HV0.2 of welded seam by LWFW (925.7 MPa) is lower than that by LBW (956.5 MPa), but the uniformity of the former is better than that of the latter. The ultimate strength of the joint by LWFW is lower than that by LBW slightly, which reach to 73.03 % and 79.22% of the base metal, respectively, whereas the elongations after fracture of the former joint is higher than that of the latter joint significantly, which reach to 38.65 % and 20.38 % of the base metal, respectively. Form those results, the microstructure and mechanical properties of 5A90 Al-Li alloy by LWFW are better than that by LBW slightly. If the combined mechanical properties of the joint by LWFW meet the operation requirements, it should be improved by heat treatment after welding, and it also should develop a better filler wire matched with the base metal.