2195-T8铝锂合金搅拌摩擦焊接头组织与力学性能

对8 mm厚度2195铝锂合金进行了搅拌摩擦焊平板对接焊试验,利用光学显微镜和扫描电镜观察分析了焊接接头的显微组织和断口形貌特征,并对接头常温、低温拉伸性能和显微硬度进行了测试。结果表明,接头整体上宽下窄,呈V字形,由焊核区、热力影响区、热影响区和轴肩影响区组成;-196℃条件下,接头抗拉强度及断后伸长率分别达到母材的71. 8%,53. 8%;焊件的硬度分布形貌均呈W状,其中焊核区微观硬度最高,热影响区微观硬度最低;接头断裂位置均位于热影响区附近,断裂特征属于典型的韧性断裂。

Microstructure and properties of 2195 Al-Li alloy welded joints by friction stir welding

2195 Al-Li alloy-plates with 8 mm in thickness were welded by friction stir welding. The microstructures and fracture morphology of the welded joints were observed by optical microscopy and SEM, the mechanical properties at both room temperature and low temperature were studied. The results showed that the top of the joint was wide and the bottom was narrow, which looks like the shape of the letter V, and there are four zones in the joint which are weld nugget zone, thermo-mechanically affected zone, heat-affected zone and shoulder-affected zone. At the temperature of -196 ℃, the tensile strength and the elongation rate of welded joint are 71.8% and 53.8% of that of the base metal, respectively. The microhardness distribution of the cross section of the joint is W shape, the maximum and minimum hardness appears in the heat affected zone and the nugget zone, respectively. The tensile fracture location of the specimens is the heat-affected zone, the fracture mode is the form of ductile fracture.