中文摘要：

针对铝合金三元气体保护焊力学性能提升原因分析的需求,使用测温系统采集铝合金纯氩气体保护、三元气体保护焊接的热循环曲线,分析焊接温度场特征的差异.研究发现三元气体保护焊温度场更加集中,峰值温度更高,降温速率更快.对纯氩气体保护、三元气体保护焊接头进行染色法观察发现,三元气体保护堆焊时晶粒更大,气孔率更低;对接焊时,三元气体保护焊接头的半熔化区存在晶界液化现象,三元气体保护焊的晶界液化现象更加严重,半熔化区宽度更窄.结果表明,焊接温度场是引起焊接接头力学性能提升的根本原因.

英文摘要：

In arc welding of aluminum,a mixture gas,with argon,helium and N2,can improve the welding process. In comparison to the pure argon MIG welding,the arc is more concentrated and allows a higher application of energy,which increases the microstructure of weld bead. Welding thermal cycle curve of Ar-He-N2 gas shielding metal arc welding and argon metal arc welding are measured,which the peak temperature is higher,the cooling rate is faster than the former. A staining method is used for the microstructure analysis. In comparison to argon metal arc welding,the grain size is larger and porosity is lower in build up welding. In comparison to argon metal arc welding,the partially melted zone is narrower in butt welding.The results of experiment show that the characteristic of welding temperature field is the basic reason for promotion of welded joint mechanical properties.