AZ31镁合金焊缝基于超声搅拌的晶粒细化方法探究

Study on grain refining of AZ31 Mg alloys weld with ultrasonic stirring

细小晶粒可以优化焊缝的力学性能,降低凝固裂纹的敏感性。该研究利用一个基于外加超声能量的全新晶粒细化方法,将超声能量直接导入焊接熔池,改变了焊接熔池的凝固过程,促进焊接熔池凝固过程中的形核,即将1根超声探针(钨丝)在电弧后面一定距离插入焊接熔池并进行超声频率搅拌,并且利用该方法在AZ31镁合金焊缝中得到了非常理想的晶粒细化效果。同时,根据试验结果及超声搅拌理论分析了AZ31镁合金焊缝晶粒细化的理论机制及超声振幅对晶粒细化效果的影响规律等。

Grain refining could improve the mechanical properties and solidification-cracking resistance of the weld. A new grain refining method of AZ31 Mg alloys weld with external ultrasonic energy was put forward. The ultrasonic energy was transferred into the weld pool with dipping an ultrasonic probe in the weld pool to stir it at a distance behind the arc. The solidification process was changed and the nucleation increased, therefore, refined grains were achieved in the weld of AZ31 Mg alloys. According to the ultrasonic stirring theories and the experimental results, the grain refining mechanism was most likely dendrite fragmentation.