Effect of static magnetic field on microstructures and mechanical properties of laser-MIG hybrid welding for 304 stainless steel

In this study, a method combining magnetic, MIG, and laser was applied to weld the 304 stainless steel with a thickness of 4 mm. The effect of magnetic field on the weld microstructures and mechanical properties was investigated. The weld geometry and microstructure were characterized by optical microscope (OM) and scanning electric microscopy. Electron back scattered diffraction (EBSD) was used to determine the grain sizes and crystallographic orientations. Residual stress and tensile stress of welds were measured and compared with the laser-arc hybrid welds without an external magnetic field. The results showed that with an appropriate magnetic field intensity, an optimal joint was obtained with tensile strength enhanced by nearly 12% and tensile residual stresses reduced. In addition, the grain refining and promotion of the phase transformation with the magnetic field were analyzed.