深冷处理对440C马氏体不锈钢组织和耐蚀性的影响

Effect of deep cryogenic treatment on microstructure and corrosion resistance of 440C martensitic stainless steel

研究了深冷处理对440C马氏体不锈钢组织和耐蚀性的影响。研究表明,液氮深冷处理后440C不锈钢硬度可提高2.3 HRC,残留奥氏体含量降低了11.7%,72 h中性盐雾试验表面无明显点蚀。440C不锈钢淬火后室温停留2 h以上残留奥氏体含量明显增加,硬度值、耐蚀性下降。实际生产中,淬火与液氮深冷处理时间间隔应不超过2 h。

Effect of deep cryogenic treatment on microstructure and corrosion resistance of 440 C martensitic stainless steel was investigated. The results show that the hardness of the 440 C stainless steel can be increased by 2.3 HRC after liquid nitrogen cryogenic treatment, the retained austenite content is reduced by 11.7%, and there is no obvious pitting on the surface after 72 h neutral salt spray test. The retained austenite content of the 440 C stainless steel increases significantly when the room temperature retention time is more than 2 h after quenching, and the hardness and corrosion resistance decrease. It is suggested that the retention time at room temperature after quenching is less than 2 h if the 440 C steel is subjected to liquid nitrogen cryogenic treatment.