Laser Welding of T91 Martensite Heat-resistant Steel with Feeding Wire

The research on laser welding 5-mm thick T91 martensite heat-resistant steel with filler wires is conducted, and the effects on weld appearance, microstructures, and porosity are studied, also the weld mechanical properties of the optimal parameter are tested. The results show that when welding heat input increased by using same material wire to weld T91 steel, weld seam width, porosity decreased, and grain size changed a little, microstructure of weld zone and HAZ are tempered martensite. The weld seam can be pore-free with the parameter of power 5 600 w, speed 1.2 m/min, feeding speed 1.2 m/min, its microhardness is 300 HV, tensile strength is 697 Mpa, no cracks appear by 180° bending and back bending, and the impact properties are better than base metal at 20/0/–20 °C.