外加磁场电流对镁合金焊接接头力学性能的影响

在对5mm厚的AZ31镁板进行TIG焊过程中，需要外加横向交流磁场.针对外加横向磁场电流对镁合金焊接接头力学性能的影响进行抗拉强度和布氏硬度试验，并采用扫描电子显微镜对试样的焊缝进行组织分析.研究了磁场参数对AZ31镁合金接头组织和性能的影响规律以及磁场作用的机理.研究发现，外加横向磁场可以促使电弧摆动对熔池进行作用，改变晶粒结晶过程，使焊缝中晶粒组织得到细化，进而使焊接接头的抗拉强度和硬度等性能得到改善.在适当的磁场参数作用下电磁搅拌达到最佳效果，此时焊接接头的综合力学性能最好.

Effect of imposed magnetic field current on mechanical properties of magnesium alloy welded joint

In the TIG welding process of AZ31 magnesium alloy plate with a thickness of 5mm,an external transverse alternating current(AC) magnetic field needs to be imposed.In order to determine the effect of external transverse magnetic field current on the mechanical properties of magnesium alloy welded joint,the ultimate tensile strength and Brinell hardness tests were performed,and the scanning electronic microscope(SEM) was used to characterize the microstructure of welded joint.The effect rule of magnetic parameters such as magnetic field current Im on the microstructure and properties of AZ31 magnesium alloy welded joint was studied,and the action mechanism of magnetic field was also investigated.The results show that the external transverse magnetic field can prompt the action of arc swinging on welding pool and change the crystallization process of grains,which will refine the microstructure of welded joint.Furthermore,such properties as the ultimate tensile strength and hardness of welded joint are improved.The optimal electromagnetic stirring effect can be achieved with adopting the appropriate magnetic field parameters,and thus the comprehensive mechanical properties of welded joint are the best.