喷丸对镁/钢焊接接头微观组织和力学性能的影响

Effects of Shot Peening on Microstructure and Mechanical Properties of Mg/Steel Welded Joints

采用TIG电弧为热源,AZ31B镁合金焊丝为填充材料,对AZ31B镁合金和镀锌双相钢进行熔钎焊连接。焊后采用高能喷丸工艺对镁/钢焊接接头进行强化处理,结合BSE、XRD、光学显微镜以及万能拉伸试验机等检测方法对AZ31B镁合金和镀锌双相钢的TIG熔钎焊接头微观组织和力学性能进行研究。结果表明:当喷丸强度为0.10 MPa时,镁/钢接头具有最大抗拉强度242 MPa,接头熔焊区的平均晶粒尺寸减小至34μm,且接头最大残余压应力达到81MPa;接头断裂位置位于镁合金母材,断面呈现良好的塑性断裂特征。

The AZ31B magnesium alloy and galvanized dual phase steel were welding-brazed with TIG arc as heat source and AZ31B wire as filler metal. After welding-brazing process, the high energy shot peening treatment was applied to strengthen the Mg/steel joint. The microstructure and mechanical properties of Mg/Steel joints were studied by BSE, XRD, optical microscope and electronic tensile testing machine. The results show that when the shot peening pressure is 0.10 MPa, the Mg/steel joint has the maximum tensile strength of 242 MPa, the average grain size of Mg/steel joint fusion zone decreases to 34 μm, and the maximum residual stress increases to 81 MPa. The fracture position of Mg/steel joint is located at magnesium alloy, and the fracture surface shows plastic fracture characteristics.