冷金属过渡条件下镁-钢的润湿动力学特征及界面结构

研究了冷金属过渡条件下AZ61镁合金分别在Q235钢板和镀锌钢板表面润湿的动力学特征，同时利用扫描电镜观察和能谱分析考察了界面微观结构.结果表明，镁合金在钢表面的最终润湿性随送丝速度的增加而变好，其中镀锌层蒸发带走热量进而相对降低了界面上的热输入，导致界面反应变弱，润湿性变差；在镁-镀锌钢界面上形成了Al-Fe金属间化合物层和脆性的Mg-Zn共晶层，导致界面结合较弱；在不同送丝速度下，镁在裸钢表面的熔滴过渡更为有效，镁-镀锌钢中镀锌层对润湿的动力学特征影响较小，两者的动力学特征都与温度依赖的毛细力相关.

Wetting dynamic characteristics and interfacial structures in CMT welding process of Mg-steel

The wetting characteristics of Mg AZ61 alloy on the surfaces of Q235 steel and galvanized steel were studied, respectively. The interfacial microstructures were also studied by using SEM and EDS. The results show that the final wettability is improved with the increase of wire feeding speed, and the wettability is worsened due to the weakened interfacial reactivity which is caused by the reducing of heat on interface.Two layers (Al-Fe intermetallic layer beneath the brittle Mg-Zn eutectic) are formed which induced the weak bonding.The transition of metal for Mg-Q235 steel is more effective and the effect of Zn coating on wetting dynamics can be negligible under different wire feeding speeds, and the dynamic characteristics both of Mg-Q235 steel and Mg-galvanized steel are related to the temperature depended capillarity.