金属间化合物对AZ31B镁/6061铝异种金属激光焊接性的影响

对AZ31B镁合金和6061铝合金进行了异种金属激光搭接焊接,并着重分析了焊缝中金属间化合物对焊接性的影响.研究表明,中心搭接接头易在铝板内的焊缝近缝区和镁、铝板界面的焊缝部位出现凝固裂纹.边缘搭接接头中不同Mg-Al系金属间化合物在焊缝中弥散分布,并非以简单的金属间化合物层的形式存在.随镁元素在焊缝中浓度梯度的变化,焊缝各局部区域形成的Mg-Al系金属间化合物类型亦因之不同.在本试验条件下,采用适当的激光加工参数可以得到无裂纹的镁/铝异种金属搭接焊缝.但由于焊缝中Mg-Al系金属间化合物不可避免,焊缝脆化现象依然存在.多种金属间化合物分布的焊缝近缝区是焊接接头的薄弱部位.

The effect of intermetallic compounds on laser weldability of dissimilar metal joint between magnesium alloy AZ31B and aluminum ahoy 6061

Laser overlap welding of dissimilar metals was performed between magnesium alloy AZ31B and aluminum alloy 6061,and the effect of intermetallic compounds(IMCs) in weld on weldability was investigated.It was found that solidification cracking was liable to occur in weld fusion region of the aluminum plate and in the weld region of the interface between plates of magnesium and aluminum for the center-line overlapped joint.Various Mg-Al series of IMCs were dispersed,rather than simply existed in form of IMC layers,in the weld of edge-line overlapped joint.The type of IMC in local regions of the weld varied according to the variation of magnesium content gradient in the weld.Non-crack welds of dissimilar metal overlapped joint of magnesium and aluminum could be achieved with appropriate laser processing parameters in the test condition.However,weld brittleness existed because of unavoidable Mg-AI series of IMCs in weld.The weld fusion region where multiple IMCs formed was the weakest part of the weld joint.