高强不锈钢激光熔覆层的组织与性能

针对核装备零部件维修再制造的需要,采用激光熔覆技术制备高强韧马氏体不锈钢熔覆层,以改善核装备零部件的表面性能,随后对熔覆层试样分别进行300 ℃和500 ℃保温2 h的回火处理。采用OM、SEM、显微硬度计、万能拉伸试验机等设备测试了试样的组织和性能。结果表明,原始试样的抗拉强度为1719 MPa,断后伸长率在15%左右,硬度为550 HV0.2,耐磨性较差;当回火温度为300 ℃时,出现逆转变奥氏体,硬度降至500 HV0.2,抗拉强度降为1662 MPa,断后伸长率超过15%,耐磨性提高;当回火温度上升到500 ℃时,逆转变奥氏体减少,碳化物逐渐析出,出现二次硬化,硬度又上升至530 HV0.2,抗拉强度降至1582 MPa,断后伸长率降至14%左右,耐磨性与原始试样相当。该高强马氏体不锈钢熔覆层整体耐腐蚀性均优于1Cr13钢,具有良好的耐腐蚀能力。

Microstructure and properties of laser clad layer on high strength stainless steel

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.