9%Ni钢配套焊条熔覆金属的组织和性能研究

Study on Microstructure and Properties of Deposited Metal of 9%Ni Steel Electrode

针对9%Ni钢使用温度低,抗拉强度高和焊条工艺性不好等问题,研制了以CaO-CaF_2-TiO_2为主的渣系和Ni-Cr-Mo-Mn-W-Nb合金系的焊条。测试了熔敷金属的力学性能,借助光学显微镜、扫描电镜和光谱分析仪对接头组织和化学成分行了分析。结果表明,研制的焊条脱渣性能良好。熔敷金属抗拉强度为648 MPa,屈服强度为442 MPa,断后伸长率为36%,满足9%Ni钢使用要求。焊缝组织为奥氏体基体+析出物,奥氏体塑性好,析出相强化基体,-196℃下平均冲击吸收功为135 J,断口为典型的韧性断裂。

For the issues of the 9% Ni steel working at low temperature, high tensile strength and bad performance of the electrode, the CaO-CaF2-TiO2 slag system and electrode with Ni-Cr-Mo-Mn-W-Nb alloy system were developed. The mechanical properties of the deposited metal were tested, and the microstructure and chemical compositon of the joint were studied by optical microscope, SEM and spectroanalysis instrument. The results show that the detachability of the developed electrode is good. The tensile strength of deposited metal is 648 MPa, the yield strength is 442 MPa and the elongation is 36%. The mechanical properties meet the requirement of 9%Ni steel. The weld microstructure is austenite matrix and precipitates. The plastic ofaustenite is good, and the precipitates strengthen the matrix. The average impact energy at -196 ℃ is 135 J, and the fracture is typical ductile fracture.