压铸态镁/铝异种金属搅拌摩擦焊接接头组织及性能

Microstructure and properties of high-pressure die casting Mg/Al dissimilar friction stir welded joints

摘要:

对3mm厚压铸态AZ91D镁合金和压铸态ADC12铝合金进行了搅拌摩擦焊，采用金相显微镜、扫描电镜、X射线衍射、万能拉伸试验机等分析了的接头的微观组织和力学性能。主要结论为：1）铝合金置于前进侧，前进速度为40mm/min，转速为900-1300r/min时，可获得成型良好的焊接接头；2）接头焊核区域镁铝合金相互混合，发生机械互锁，组织呈现条带状特征；母材中粗大铸态枝晶明显细化，非镁/铝基体相主要有Si、Mg2Al3、Mg17Al12和Mg2Si，颗粒状尺寸随转速的增加呈先降后增趋势； 3）接头平均抗拉强度随转速增加呈现先增大后减小的趋势；断裂均发生在前进侧热机影响区和焊核的交界处。

Abstract:

The high-pressure die castings of AZ91 Mg and ADC12 Al alloys of 3 mm were welded by frciton stir welding. OM、SEM/EDS、XRD and universal tensile testing machine were used to analyze the microstructure and tensile property of the joint. The main conclusins are: 1). Defect-free welded joints were obtained when ADC12 die-casting aluminum alloy was placed in advancing side with a welding speed of 40mm/min and the rotational speeds of 900-1300r/min. 2). Mg and Al alloys are mixed with each other in the nugget zone, and mechanical interlocking occurs. In the parent material, the thick and large casting dendrites are obviously refined, and the non-Mg/Al matrix phases mainly include Si, Mg2Al3, Mg17Al12 and Mg2Si. 3) The average tensile strength of the joints increased first and then decreased with the increase of rotating speed. Fracture occurred at the interface of the thermal affceted zone and the nugget zone in advancing side.