深冷处理对NM500耐磨钢性能与磨损行为的影响

以一种自行设计的NM500级别耐磨钢为研究对象,利用冲击磨损试验,分析了深冷处理对其组织性能和磨损行为的影响。结果表明,NM500耐磨钢经深冷处理后,抗拉强度、硬度和冲击韧性均有提高,在淬火+深冷+回火处理后,最佳的综合力学性能可达抗拉强度1 910 MPa、硬度523HB、冲击韧性24.3 J/cm2,此时试验钢组织主要为马氏体,有Nb和Ti的碳化物析出。深冷处理通过残余奥氏体向马氏体转变,减少了不稳定相的含量,提升了试验钢的力学性能,从而使淬火+深冷+回火处理后的试验钢具有更高的耐磨性,此时的磨损机制以磨粒磨损为主,磨损形貌主要为犁沟、犁皱。而未经深冷处理的淬火+回火处理试验钢磨损机制以黏着磨损为主,磨损形貌主要为剥落坑和切削。

Effect of cryogenic treatment on mechanical properties and wear behavior of NM500 wear resistant steel

A self-designed NM500 wear-resistant steel was investigated by impact abrasive wear test. The effect of cryogenic treatment on microstructure, mechanical properties and wear behavior of the experimental steel was analyzed. The results showed that the tensile strength, hardness and impact toughness of the experimental steel were improved after cryogenic treatment. After quenching, cryogenic treatment and tempering treatment, the obtained optimal mechanical properties were that the tensile strength was 1 910 MPa, the hardness was 523HB and the impact toughness was 24.3 J/cm2. The microstructure of this sample was martensite with Nb and Ti carbides. Through the transformation of retained austenite to martensite, cryogenic treatment reduced the content of the unstable phase and improved the mechanical properties. Thus, after quenching, cryogenic treatment and tempering treatment, the test steel had better wear resistance, whose wear mechanism was mainly abrasive wear and wear morphology was mainly furrows. Without cryogenic treatment, for the sample after quenching and tempering treatment, the wear mechanism was abrasive and the wear morphology was peeling pits and cutting.