Comparison between Microstructures and Properties of Weldox960 Steel Welded Joints by Laser-MAG Welding and MAG Welding

Weldox960 steel plates were welded by laser-metal active gas arc welding (Laser-MAG welding) and MAG welding, and then the microstructures and properties of the welded joints by two processes were compared and analyzed. The results show that the average grain size in coarse-grained heat affected zone of the Laser-MAG welded joint was relatively small, which was 48 μm, while that of the MAG welded joint was 95 μm. The microstructures of the two welded joints were basically the same; the weld metal was composed of fine granular bainite, the fine grained zone consisted of fine lath martensite and granular bainite, and the partial phase transition zone consisted of ferrite and granular bainite. The heat affected zone of the Laser-MAG welded joint was narrower than that of the MAG welded joint and had a relatively narrow softening band. The tensile performance and impact performance were better than those of the MAG welded joint, and the conditional fatigue limit was 320 MPa, higher than that of the MAG welded joint.