Microstructure and mechanical properties of magnesium alloy AZ31B solder joint using Zn-Mg filler metal

In order to join wrought magnesium alloy AZ31B sheet high-frequency induction soldering of wrought magnesium alloy AZ31B using Zn-Mg filler metal was investigated. The microstructure of the Zn-Mg filler metal was evaluated. Both the interface microstructure and the mechanical properties of the solder joint were studied. The interface microstructure and formation phases of the soldering seam were investigated by X-ray diffractometer, scanning electron microscopy and X-ray energy dispersive spectrometer. The strength of the solder joint and the microhardness of the interface microstructure were tested. The results show that Zn-Mg filler metal reacts with the base metal AZ31B, and α-Mg matrix and α-Mg +γ-MgZn eutectoid structure are formed in soldering seam, and the microstructure in the original Zn-Mg filler metal disappearing after the soldering process. The average tensile strength of the butt joint is 51 MPa and the average shear strength of the overlap joint is 36 MPa. The microhardness of the α-Mg +γ-MgZn eutectoid structure is the maximum in the solder joint. The fracture morphology of the solder joint exhibits intergranular fracture mode and the fracture comes from α-Mg +γ-MgZn eutectoid structure.