The comparison of multi-layer narrow-gap laser and arc welding of S32101 duplex stainless steel

Multi-layer narrow-gap welding of thick S32101 duplex stainless steel was conducted using laser welding with beam wobble process. The phase transition, grain size, phase proportion and crystal texture of welded joint were also studied and compared with gas metal arc welding process. The microhardness and tensile strength were measured and fracture surface was analyzed to evaluate the mechanical properties of welded joints. The results showed that beam wobble technology improved the misalignment of laser beam and filler wire in narrow groove and helped to avoid incomplete fusion defects. Compared to arc welding process, the groove size and heat input were reduced, while welding efficiency was increased. The faster cooling rate and lower temperature gradient of laser wobble welding favored grain refinement, while the austenite content in weld zone decreased. Both the beam wobble and swing arc were conducive to stir weld pool, optimizing the weld microstructure and joint formation. The microstructural variance in various weld passes was caused by the heat input and heat dissipation ability. The microhardness of laser welded joint was lower, while the tensile strength and elongation percentage were higher. The fracture surface of arc welded joint was featured with shallower dimples and cleavage steps.