采用Al-Mg-Sc-Zr焊丝为填充材料对Al-Mg-Sc合金薄板进行手工非熔化极惰性气体保护焊(TIG焊), 并对焊接接头进行350 ℃下保温1 h的焊后热处理.通过拉伸实验、显微硬度测试、SEM及TEM观察对热处理前、后的Al--Mg--Sc合金焊接接头的力学性能及微观组织进行了对比研究.结果表明:热处理前焊接接头强度为 332 MPa; 经350 ℃/1 h热处理后,焊接接头强度增至410 MPa, 焊接接头强度系数达到0.98, 焊接接头延伸率由5.6%增加至14.4%, 并且焊缝区的显微硬度得到大幅度提高, 拉伸时断裂位置由焊缝区转移到了熔合区. 焊后热处理使焊缝区析出大量弥散分布的Al3(Sc, Zr)粒子, 这些粒子与基体共格, 使焊缝区的硬度、抗拉强度和屈服强 度大幅度提高.
In this research, Al-Mg-Sc alloy sheets were welded by manual TIG(tungsten inert gas) welding method with Al-Mg-Sc-Zr welding wire as filling material, and the welded joints were processed heat treatment after welding under 350℃for 1h. Mechanical properties and microstructures of welded joints without and with heat treatment were studied comparatively using tensile test, micro-hardness measurement, SEM and TEM analysis methods. The results show that：as the result of 350℃/1h heat treatment, tensile strength and elongation percentage of welded joints increased to 410Mpa and 14.4%from 332 MPa and 5.6% correspondingly, which were that of without heat treatment, and welded joint coefficient reached to 0.98. After heat treatment, micro-hardness of welded zone was raised greatly, and failure position was fusion zone instead of welded zone. On the process of heat treatment, large amounts of Al3(Sc, Zr) particles, which are coherent with matrix, precipitated and deposited uniformly in the welded zone, leading to great improvement of hardness, tensile strength and yield strength of welded zone.
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