磁场对AZ31镁合金焊接接头疲劳性能的影响

为了研究外加磁场对焊接接头疲劳行为的影响规律，在对5 mm厚的AZ31镁合金板进行钨极氩弧焊过程中，外加纵向交流变频磁场.对不同磁场参数下镁合金焊接接头进行应变控制疲劳实验，采用光学金相和扫描电镜对焊接接头的显微组织和疲劳断口进行分析.实验结果表明：当磁场电流为2 A，频率为20 Hz时，焊缝的疲劳性能达到最佳值.合适的外加纵向磁场可以促使电弧旋转对熔池进行搅拌，改变晶粒结晶过程，使焊缝中晶粒组织得到细化，进而使焊缝的疲劳性能得到改善.

Influence of magnetic field on fatigue performance of AZ31 magnesium alloy welded joint

In order to study the influence of imposed magnetic field on the fatigue performance of welded joints,the longitudinal alternating magnetic field was introduced in the GTAW process of AZ31 magnesium alloy plate with a thickness of 5 mm.The strain controlled fatigue tests were carried out for the magnesium alloy welded joints obtained under different magnetic field parameters.The microstructures and fatigue fracture surfaces of the welded joints were analyzed by optical microscope and scanning electronic microscope(SEM),respectively.The results show that when the magnetic field current is 2 A and the frequency is 20 Hz,the fatigue performance of the welded joints reaches the optimal value.The suitable external longitudinal magnetic field can promote the arc rotation to stir the welding pool,change the crystallizing process to refine the microstructures of the welded joints,and thus improve the fatigue performance of the welded joints.