含钪Al-Zn-Mg-Zr合金薄板材MIG焊接接头的组织与性能  

Microstructures and properties of MIG welded joint of Al-Zn-Mg-Zr aluminum alloy sheet containing Sc

作　　者：李波[1] 潘清林[2] 陈从平[1] 吴海华[1] 尹志民[2] 

机构地区：[1]三峡大学机械与动力学院,宜昌443002 [2]中南大学材料科学与工程学院,长沙410083

出　　处：《粉末冶金材料科学与工程》2016年第5期767-774,共8页Materials Science and Engineering of Powder Metallurgy

基　　金：湖北省教育厅科学技术研究计划优秀中青年人才项目(Q20161202);水电机械设备设计与维护湖北省重点实验室开放基金(2016KJX04);国家自然科学基金资助项目(51475266)

摘　　要：采用新型Al-Mg-Sc-Zr焊丝对含钪Al-Zn-Mg-Zr合金薄板材进行MIG焊,借助显微硬度及拉伸性能测试、OM,SEM,TEM等检测手段对焊接接头的微观组织和性能进行研究。结果表明:焊缝区为典型的铸态组织;热影响区靠近焊缝一侧呈现大量细小等轴晶组织,靠近基材区为纤维状组织和少量再结晶组织;基材区为纤维状组织。焊接接头的显微硬度以焊缝为中心呈近似对称,且中心处硬度值最低;抗拉强度为481 MPa,屈服强度为320MPa,伸长率为10.1%,焊接系数约0.83。同时,焊丝和基材中微量的Sc和Zr元素在合金中形成大量细小且与基体共格的Al3(Sc,Zr)粒子,能显著细化晶粒组织,有效抑制再结晶发生,大大改善焊缝区的力学性能。Al-Zn-Mg-Sc-Zr alloy sheet was welded using novel Al-Mg-Sc-Zr welding wire by the method of metal inert gas（MIG） welding. Microstructures and mechanical properties of the welded joint were investigated by OM, SEM, TEM, microhardness test and tensile test. The results show that the weld zone exhibits typical cast structures consisting of dendritic α-Al. Besides, a large number of fine equiaxed grains form in the fusion zone on one side of the welding line as well as a small amount of recrystallization and fibrous structure on the other side. The fibrous organization is obviously found in the base metal. The hardness curve in the cross-section presents symmetrical distribution along weld centerline, and the minimum hardness appears in the region of fusion zone. The tensile strength, yield strength, elongation and welding coefficient of the welded joint are 481 MPa, 320 MPa, 10.1% and 0.83, respectively. Meanwhile, trace amount of Sc and Zr elements in welding wire and alloy sheet form fine, coherent Al3（Sc,Zr） particles with L12 structure, which can refine grain, inhibit recrystallization and improve mechanical properties.

关 键 词：钪 Al-Zn-Mg-Zr合金 MIG焊 显微组织 力学性能 

分 类 号：TG40[金属学及工艺—焊接]