镁-铝异种金属冷金属过渡连接焊接性分析

Analysis of weldability of Mg-Al dissimilar metal cold metal transfer welding

通过CMT(Cold Metal Transfer)冷金属过渡焊接的工艺对镁(AZ31B)-铝(6061)异种金属焊接性进行了研究,试验中选用AZ61,4043焊丝、采用热镀锌钢板HDG60作为过渡金属,分别用于镁-钢、铝-钢侧焊接,选取合适的焊接工艺参数,使其间接实现了镁-铝异种金属连接的目的。研究得出:使用这种方法可以形成镁-钢熔钎焊焊接接头,铝-钢熔钎焊焊接接头组成的复合接头;同时冷金属过渡焊接可以通过保持较低焊接热输入从而降低界面反应层的厚度;而且镀锌钢板中间过渡层的使用也避免了镁-铝直接焊接时形成的脆性金属间化合物,如Al_3Mg_2,Mg_(17)Al_(12)等。采用该方法连接的镁-铝异种金属焊接接头的抗拉强度超过180 MPa,并且有较好的断后伸长率,相比铝镁异种金属CMT直接焊接,性能得到很大的改善,因此使用镀锌钢板中间过渡层的使用实现铝镁异种金属之间的连接是一种行之有效的方法。

An investigation of dissimilar metal joining between AZ31 B Mg and 6061 Al by CMT( Cold Metal Transfer) welding was conducted. To achieve successful welding of Mg-Al dissimilar metals,hot-dip galvanized steelplate of HDG60 was selected as transition metal,AZ61 and 4043 welding wires were utilized in welding process of Mg-steel and Al-steel,respectively,and different welding parameters were used on each side. It is shown that the heat input is controlled effectively and the interface reaction layer is thin via CMT welding. The vacancy of brittle Al3Mg2 and Mg17Al12 intermetallic compounds during the direct welding of Mg to Al can be attributed to the appropriate selection of transition metal. The mechanical properties of the welded joint were optimized because MgZn,FeAl3 and Fe2Al5 phases with smaller thickness are mainly formed on the welded joint interface. For example,the tensile strength is higher than 180 MPa and the elongation is good with regard to the CMT welded joint of Mg-Al dissimilar metals,which indicates that the Mg-Al dissimilar metal can be joined effectively by means of the transition metal.