镁和钛异种金属冷金属过渡焊接接头微观组织及力学性能的分析

Analysis of Microstructure and Mechanical Properties for Welding Joints of Dissimilar Metals between Magnesium and Titanium by Cold Metal Transfer Method

采用冷金属过渡焊接技术,对AZ31B镁合金、工业纯钛TA2异种金属熔钎焊焊接性进行探索研究,从焊接接头的微观组织、元素分布状况研究其连接机理。结果表明:冷金属过渡焊接技术是一种适用于镁、钛异种金属连接的有效方法。通过在过渡区和结合面形成新相可以实现镁、钛的有效连接。焊接接头的焊缝区主要由镁的固溶体?-Mg,骨架状的镁铝金属间化合物Mg17Al12,以及颗粒状分布的Mg17Al(Zn)12组成。镁钛结合面主要靠钛和铝的金属间化合物Ti3Al,以及镁铝金属间化合物Mg17Al12和Mg17Zn12连接。同时,焊接过程中Ti原子以及Al原子的扩散对其结合也有一定的影响。因此,焊接过程中必须保证足够的热输入量,以确保钛母材的熔化及钛、铝原子的扩散,从而提高其结合强度。

Welding-brazing joining of Dissimilar metals between AZ31B Mg alloy and industrial pure titanium TA2 is studied by cold metal transfer （CMT） welding technology. The microstructure, element distribution of the welding joints were analyzed to show joining mechanism. The results show that, cold metal transfer welding technology is a feasible method for dissimilar metals Mg and Ti joining. The gagnesium and titanium sheets can be joined by forming new phases in the transition joining zones. The weld metal zone is constituted by ct-Mg solid solution ,skeleton shaped Mg17A112 intermetallic compound, and granular distributed Mgl7Al（Zn）12 The joining of magnesium and titanium mainly depends on the Ti3A1, and Mg17A112 intermetallic compounds. At the same time, diffusions of Ti atoms and A1 atoms also affect the formation of the joints during welding process. Therefore, enough quantity of heat input must be ensured to make the local titanium parent metal to melt and titanium atomic diffuse, so as to improve the joining strength during the welding process.