不同铝热剂对镁/钢点焊接头组织和性能的影响  

Effect of Thermite on Microstructure and Mechanical Properties of Mg/Steel Resistance Spot Welds

作　　者：袁涛[1] 张禹[1] 李洋[1] 罗震[1,2] 王证茗 谈辉 

机构地区：[1]天津大学材料科学与工程学院,天津300072 [2]高新船舶与深海开发装备协同创新中心,上海200240

出　　处：《上海交通大学学报》2016年第S1期106-109,共4页Journal of Shanghai Jiaotong University

基　　金：高等学校博士学科点专项科研基金(20130032110004);国家自然科学基金面上项目(51275342);国家自然科学基金面上项目(51275338);国家自然科学基金青年项目(51405335)

摘　　要：采用粉末铝热剂介入型电阻点焊技术,研究了不同铝热剂粉末(Al+Fe_2O_3,Al+Cr_2O_3和Al+CuO)对电阻点焊显微组织和力学性能的影响.结果表明,镁/钢点焊接头主要由熔核区(FZ),热影响区(HAZ)和母材(BM)组成.镁合金一侧熔核主要由胞状树枝晶和等轴晶/等轴树枝晶组成,在熔核边缘具有明显的联生结晶特点,且晶体生长方向近似垂直于熔合线.由于铝热剂降低了熔核中心周围区域温度梯度,并可以作为异质形核点,从而促进等轴树枝晶的形核和长大.添加铝热剂Al+Fe_2O_3,Al+Cr_2O_3和Al+CuO后,点焊接头的拉剪强度分别比直接点焊接头提高了16.4%,34.6%和31.3%.This paper applies interventional powder thermite on the resistance spot welding(RSW)process.The effects of the interventional powder thermite(Al+Fe_2O_3,Al+Cr_2O_3,and Al+CuO)on the microstructure and the mechanical properties of Mg/Steel resistance spot welds were investigated.The results showed that the weld joint consists of fusion zone(FZ),heat affected zone(HAZ)and base metal(BM).The nugget in the Mg side is composed of cellular dendritic grains and equiaxed dendritic grains.Epitaxial solidification was observed in the edge of nugget,and the growth direction of grains is perpendicular to the fusion line.The reaction of thermite reduces the temperature gradient in the weld nugget.The thermite powders as heterogeneous nucleation sites promote the formation and growth of equiaxed dendritic grains.Under the action of thermite Al+Fe_2O_3,Al+Cr_2O_3,and Al+CuO,the tensile shear force can be enhanced by 16.4%,34.6% and 31.3%,respectively.

关 键 词：电阻点焊 镁钢异种连接 铝热剂 显微组织 力学性能 

分 类 号：TG453.9[金属学及工艺—焊接]