5B70铝合金变极性等离子焊接接头组织与性能的研究  

Microstructures and mechanical properties of Al-Mg-Sc alloy 5B70 welded joints by variable polarity plasma arc welding

作　　者：苏志强[1] 刘娟[1] 李延民[1] 王金亮[1] 白华屹 张勤练[2] 蔡玉博 林三宝[2] 

机构地区：[1]首都航天机械公司,北京100076 [2]哈尔滨工业大学先进焊接与连接国家重点实验室,黑龙江哈尔滨150001

出　　处：《机械制造文摘（焊接分册）》2014年第4期12-16,共5页Welding Digest of Machinery Manufacturing

摘　　要：以5B71合金焊丝为填充材料,采用变极性等离子弧焊法对6 mm厚5B70合金板材进行焊接,并对焊接接头进行显微组织和力学性能的研究。结果表明:接头的抗拉强度达到370.13 MPa,强度系数为0.89,断后伸长率为10.35%;断裂发生在靠近熔合区的热影响区处,断口形貌为韧窝,属于塑性断裂;焊缝中心的硬度是整个焊接接头最低的区域;焊缝组织由大量树枝晶和少量等轴晶组成,熔合区界限明显,形成了等轴晶层,热影响区范围很窄,保留了与母材类似的纤维状组织。Al-Mg-Sc alloy 5B70 plates whose thickness is 6 mm was welded by variable polarity plasma arc welding and the microstructures and mechanical properties of the joints were investigated. Results indicated that the joints with excellent mechanical properties can be obtained. The tensile strength could reach up to370.13 MPa which was the 89% of that of the parent metal and the maximum elongation at fracture was10.35%. This is comparable with that of the parent metal. The microstructures in the weld zone was composed by equiaxed crystals and little dendrite crystals. A fine equiaxed crystals cladding emerged in the fusion zone and the columnar crystals were not found out. The microstructures coarsening phenomena did not occur in the heat affected zone. The fine microstructures of the welding joints contributed to the enhancement of its mechanical properties. The analysis concluded that the microstructures and mechanical properties features of the welding joint benefited from the addition of the microelement Sc.

关 键 词：铝镁钪合金 变极性等离子 焊缝组织 力学性能 

分 类 号：TG407[金属学及工艺—焊接] TG457.14