电梯用含氮节镍奥氏体不锈钢QN1701的组织和性能

借助Thermo-Calc热力学相图计算软件,开发了用于电梯的含氮节镍奥氏体不锈钢QN1701(12Cr17Mn7Ni2Cu2N),以代替443(019Cr21CuTi)超纯铁素体不锈钢。通过OM、SEM和电化学工作站等方法研究了QN1701和443不锈钢的组织及性能。N原子起着间隙固溶和细晶强化的作用,使QN1701不锈钢的屈服强度提高至400 MPa以上,达到443不锈钢的1.32倍。QN1701不锈钢的点蚀电位为241 mV,低于443不锈钢的289 mV,但其点蚀速率为9.10 g/(m2·h),低于443不锈钢的14.58 g/(m2·h)。在电梯用研磨拉丝表面状态下,QN1701不锈钢在质量分数为10%NaCl中性盐雾和干湿循环盐雾等加速腐蚀试验中的耐蚀性能均优于443不锈钢。分析发现,443不锈钢添加一定量的Nb、Ti稳定化元素所生成的(Nb,Ti)(C,N)析出相经研磨拉丝处理后,暴露于表面或被拖拽后留下微坑,导致其耐蚀能力急剧下降。综上所述,相较443不锈钢,QN1701不锈钢具有强度更高、伸长率更大和在研磨拉丝表面状态下耐蚀性更好等特点,这对于电梯轻量化设计和长寿命具有重要价值。

Microstructure and properties of nitrogen contained low nickel austenitic stainless steel QN1701 for elevator

Nitrogen contained low nickel austenitic stainless steel QN1701(12Cr17Mn7Ni2Cu2N)was designed by Thermo-Calc software to replace 443(019Cr21CuTi) ultra pure ferritic stainless steel for elevator. Microstructure and properties of QN1701 and 443 stainless steel were investigated by means of OM, SEM, Electrochemical workstation and other methods. It was shown that yield strength of QN1701 stainless steel was increased to more than 400 MPa and was 1.32 times of that of 443 stainless steel for nitrogen playing a role of grains refining and solution strengthening. The pitting potential of QN1701 stainless steel was 241 mV, which was lower than 289 mV of 443 stainless steel, but its pitting rate was 9.10 g/(m2·h), which was lower than 14.58 g/(m2·h) of 443 stainless steel. The corrosion resistance of QN1701 stainless steel was significantly better than that of 443 stainless steel in the accelerated corrosion tests with environment of 10%NaCl neutral salt spray and cyclic exposure of wet and dry salt spray under the condition of grinding and wire drawing surface for elevator plate. The analysis found that (Nb,Ti) (C,N) precipitations generated by adding a certain amount of Nb and Ti to 443 stainless steel after grinding and wire drawing process, exposed to the surface or left a small pit after being dragged, which led its corrosion resistance to be reduced. In conclusion, QN1701 stainless steel has the characteristics of higher strength, elongation and better corrosion resistance on wire drawing surface, which is of great value for the light-weight design and longer service life of elevator.