Mo和Ni对低合金耐磨钢连续冷却转变的影响

Effect of Mo and Ni on continuous cooling transformation of low alloy wear-resistant steel

用热力模拟实验机测定了不含Mo和Ni、含Mo不含Ni、含Mo和Ni 3种成分低合金耐磨钢的连续冷却转变(CCT)曲线,用光学显微镜、透射电镜观察了连续冷却过程中的显微组织,研究了连续冷却条件下的组织演变规律,分析了Mo和Ni元素对显微组织和硬度的影响。结果表明:随冷速的增加,试验钢的转变组织主要有铁素体、粒状贝氏体、板条贝氏体以及板条马氏体。Mo、Ni的添加使耐磨钢在低冷却速率下抑制了铁素体相变,促进了贝氏体相变;在高冷却速率下促进了马氏体相变,提高了临界冷却速率。Ni的添加对显微硬度的增加作用更明显。

Continuous cooling transformation diagrams were determined for three low alloy wear-resistant steels with different composition（without Mo/Ni,with Mo,with Mo and Ni） by a thermal simulator.Continuous cooled microstructure was observed by means of optical microscope and transmission electron microscopy.Microstructure evolution behavior of the wear-resistant steels was investigated and the influences of addition of Mo/Ni on microstructure and hardness of the steels were analyzed.The results show that microstructure in continuous cooled specimens are composed of ferrite,granular bainite,lath bainite and lath martensite.Mo and Ni addition effectively suppresses ferrite formation and promotes bainite formation at lower cooling rate,and promotes formation of martensite at higher cooling rate and lowers the critical cooling rate of martensite.Hardness of the specimen is more effectively increased by adding Ni.