变形及合金元素对NM400连续冷却转变的影响
Effects of Deformation and Alloy Elements on Continuous Cooling Transformation of NM400 Steel
曹 艺, 王昭东, 吴 迪, 王国栋
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作者单位：东北大学 轧制技术及连轧自动化国家重点实验室, 辽宁 沈阳 110819
中文关键字：NM400； 连续冷却； 合金元素； 变形； 临界冷却速率
英文关键字：NM400; continuous cooling; alloy elements; deformation; critical cooling rate
中文摘要：用MMS-200热力模拟试验机研究了低合金耐磨钢NM400在连续冷却条件下的组织演变规律，测定了不同化学成分钢的静态CCT曲线和动态CCT曲线，分析了变形及合金元素对组织转变的影响。结果表明：奥氏体区的变形促进铁素体相变，贝氏体相变温度降低，形成马氏体临界冷却速率提高。Mo抑制碳的扩散，细化晶粒，Ni的添加更加降低马氏体的临界冷却速率。冷速在10 ℃/s以上时，硬度超过400 HV，传统离线淬火及轧后在线超快冷工艺生产NM400钢均具有可行性。
英文摘要：The continuous cooling transformation behavior of low alloy wear-resistant steel NM400 was investigated by MMS-200 thermal simulator. The static CCT and dynamic CCT diagrams of different content steels were investigated. The influences of deformation and alloy elements on the microstructure transformation of the steels were analyzed. The results show that the hot deformation slightly promotes the formation of ferrite. The temperature of bainite transformation decreases. The critical cooling rate of martensite transformation increases. Addition of Mo depresses the diffusion of carbon and refines the grains. The critical cooling rate of martensite formation is decreased more effectively by adding Ni. The hardness of the steels is over 400 HV at the cooling rates above 10 ℃/s, and it is feasible to produce NM400 steel by traditional quenching or ultra fast cooling (UFC).