Abstract: In response to the need for repair and remanufacturing of nuclear equipment parts, the laser cladding technology was used to prepare the clad layer of high-strength and tough martensitic stainless steel for improving the surface properties of nuclear equipment parts, and then the clad layer specimens were tempered at 300 ℃ and 500 ℃ for 2 h. The microstructure and properties of the specimens were tested by means of OM, SEM, microhardness tester, universal tensile testing machine and other equipment. The results show that the original specimen has the tensile strength of 1719 MPa, percentage elongation after fracture of about 15% and the hardness of 550 HV0.2, the wear resistance of which is poor. When the tempering temperature is 300 ℃, the reverse transformed austenite appears, resulting in the decrease of hardness and the tensile strength to 500 HV0.2 and 1662 MPa, respectively, while the elongation after fracture exceeds 15%, the wear resistance of parts is improved. When the tempering temperature increases to 500 ℃, the content of reverse transformed austenite decreases and the carbides gradually precipitate, the secondary hardening occurrs, the hardness increases to 530 HV0.2, the tensile strength decreases to 1582 MPa, the elongation after fracture decreases to 14%, and the wear resistance of parts is equivalent to the original specimen. The overall corrosion resistance of the clad layer of high-strength and tough martensitic stainless steel is better than that of the 1Cr13 steel, and has good corrosion resistance.

Key words: laser cladding, nuclear equipment, high strength stainless steel, microstructure and properties