高低温循环试验下磁脉冲焊接接头性能研究

Properties of magnetic pulse welded joints at high and low temperature cycling experiments

磁脉冲焊接是一种高效的固相焊接工艺,对异种金属材料在汽车轻量化中的运用具有积极意义.通过对5052Al/HC420LA板件磁脉冲焊接接头进行不同条件下的高低温循环试验,对比焊接接头在高低温循环试验前后的力学性能变化,研究了高低温循环冷却方式、循环次数对焊接接头性能的影响.利用扫描电子显微镜(SEM)研究了焊接接头微观形貌特征,分析了高低温循环试验前后焊缝微观界面的特征及其变化.研究表明:不同高低温循环试验条件下5052Al-HC420LA铝-钢磁脉冲焊接接头的连接强度相比于5052铝合金的母材强度下降了5%～25%;冷却速度越快,高低温循环次数越多,接头力学性能下降越明显;接头在高低温循环试验前后出现了母材失效与焊缝失效两种剪切失效模式;水冷冷却的接头比空冷冷却更易产生微观裂纹.

Magnetic pulse welding is a kind of efficient solid-state welding process, which is positive for the application of dissimilar metal materials in automobile lightening. In this paper, high and low temperature cycling experiments were carried out under different conditions for 5052AI/HC420LA plate magnetic pulse welding joints. Comparing with the mechanical properties of welded joints before and after high and low temperature cycling experiments, the effects of cooling modes and cyclic numbers on the properties of welding joints were studied. The micro-structure of welded joints was studied by SEM, and characteristics and changes of micro-interface features before and after high and low temperature cycling experiments were compared. The results show that the connection strength of the 5052A1-HC420LA magnetic pulse welded joints were reduced by 5% - 25% under different conditions compared to the strength of 5052 aluminum alloy base metal. Moreover, the mechanical property of the joint decreased with the increase of cooling rate and cycling numbers. Two shearing failure modes （failure of base metal and failure of welding seam） were obtained before and after high and low temperature cycling experiments. Water-cooled cooling joints were more likely to produce microscopic cracks than air-cooled cooling.