磁场参数对镁合金焊接接头力学性能的影响

在对5 mm厚的AZ31镁合金板进行TIG焊过程中,施加纵向交流变频磁场.试验过程中调节磁场参数对试样进行抗拉和硬度试验,采用扫描电子显微镜及光学金相显微镜对试样的焊缝进行显微组织和断口分析,研究磁场参数对AZ31镁合金接头组织和力学性能的影响规律,并对磁场作用机理进行研究.结果表明,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,进而使焊接接头的抗拉强度和硬度等性能得到改善;当磁场电流为2 A,频率为20 Hz时,焊缝的力学性能达到最佳值,此时硬度为76.2 HV,抗拉强度为231 MPa.

Effect of magnetic field parameters on properties of magnesium alloy welded joint

During the welding of AZ31 magnesium alloy plate(5 mm), AC longitudinal and variable frequency magnetic field was used, and the tensile strength and microhardness of welded joint at different magnetic field parameters were tested.With scanning electronic microscope and metallographic microscope, the microstructure of welded joint was analyzed.The effect of magnetic field on the mechanical properties and microstructure of welded joint were studied, and the function mechanism of magnetic field was explored.The results show that the AC longitudinal magnetic field stirs welding pool through the rotating arc, changes the crystallizing process of crystal grains to refine them, which makes the hardness and tensile strength of welded joint improved.Under the proper magnetic field parameter, the electromagnetic stirring achieves the best effect.When magnetic field current I_c=2 A, frequency f=20 Hz, the mechanical properties of welded joint will reach the best value.The hardness is HV 76.2, and the tensile strength is 231 MPa, which is 90% of base metal.