Effect of laser heat treatment on microstructure and properties of S32101 repair zone

S32101 dual-phase stainless steel plate was repaired by laser wire filling welding method. Under technological parameters of laser power 5 kW, spot diameter 5 mm, welding speed 8 mm/s, wire feeding speed 260 cm/min, shielding gas flow rate 30 L/min, well-formed welds were obtained. The influence of laser heat treatment under different power on microstructure, mechanical properties and corrosion resistance of repair zone was studied. The results showed that austenite grain was refined and content of austenite increased after laser heat treatment. The microhardness of repair zone decreased, but was still higher than that of base metal. When laser power of heat treatment was 0～3 kW, tensile strength increased with increase of laser power. When laser power reached 4 kW, the tensile strength decreased, and tensile fracture morphology of repair zone was typical ductile fracture. By measuring TAFEL polarization curve of repaire zone, it was found that self-corrosion potential of repair zone increased and self-corrosion current density decreased after laser heat treatment,which ineicated that corrosion resistance of repair zone was improved.Highlights: (1) Method of laser heat treatment was used for postweld treatment of laser welding repair zone of S32101.(2) Effects of laser heat treatment with different power (0～4 kW) on microstructure, mechanical properties and corrosion resistance of repair zone were analyzed.(3) After laser heat treatment, austenite content of S32101 repair zone was improved to a certain extent, and mechanical properties and corrosion resistance were improved to a certain extent.