摘要
中锰马氏体耐磨钢具有低成本、高强度、高硬度和高耐磨性等特点,在煤炭采运、水泥搅拌和轨道交通等领域具有广阔的应用前景。利用金相显微镜、扫描电子显微镜和透射电子显微镜等设备,以中锰马氏体NM500钢为研究对象,研究了终轧温度对其热处理后组织和力学性能的影响。研究结果表明,与热轧态试样相比,经850℃保温1 h热处理后,试验钢的原始奥氏体晶粒明显细化,相变后的马氏体组织更加细小,低温冲击韧性大幅提升,且较低的终轧温度使得基体中缺陷密度增加,V(C,N)的数量增大,粒径减小,更有利于再加热过程中奥氏体晶粒的细化。当终轧温度由900℃降低至700℃时,经再加热后,试验钢的原始奥氏体晶粒尺寸由10.50μm细化至5.02μm,马氏体的板条块尺寸由1.37μm减小至1.06μm,位错密度由1.05×10^(15)m^(-2)增加至1.51×10^(15)m^(-2)。马氏体多级组织的细化以及位错密度的增加,显著提升了细晶强化增量和位错强化增量,使得试验钢的抗拉强度、屈服强度和硬度分别增加至1 860 MPa、1 084 MPa和540HB。同时,组织的细化使得基体中大角度晶界密度增加,裂纹扩展的阻碍增多,冲击断口上的韧窝增多且尺寸增大,韧性提升,-40℃下的冲击吸收能量达到25.5 J。
Medium manganese martensitic wear-resistant steel has broad prospect of application in the fields of coal mining,cement mixing and rail transportation with the characteristics of low cost,high strength,high hardness and high wear resistance.The effect of finish rolling temperature on the microstructure and mechanical properties of medium manganese martensitic NM500steel after heat treatment was investigated using metallographic microscope,scanning electron microscope and transmission electron microscope.The results showed that compared with the hotrolled specimens,the prior austenite grain size of the experimental steel was significantly refined after the heat treatment of holding at 850℃for 1h.The martensite microstructure after phase transformation was finer and the lowtemperature impact toughness was greatly improved.The lower finish rolling temperature increased the defect density in the matrix and the amount of V(C,N)with reducing the grain size,which had more benefits for the refinement of austenite grains during the reheating process.When the finish rolling temperature deceased from 900℃to 700℃,the prior austenite grain size of experimental steel was refined from 10.50μm to 5.02μm and the block width decreased from 1.37μm to 1.06μm.The dislocation density increased from 1.05×10^(15)m^(-2) to 1.51×10^(15)m^(-2).It was found that the refining martensite and increasing dislocation density significantly enhanced the grain refinement strengthening and dislocation strengthening,resulting in the tensile strength,yield strength and Brinell hardness of the experimental steel increasing to 1860MPa,1084MPa and 540HB,respectively.Meanwhile,the microstructure refinement led to a significant increase in the density of high angle grain boundaries in the matrix,which effectively inhibited crack propagation.The number and the size of dimples present at the fracture surface increased,and the toughness of experimental steel was improved.The impact absorption energy at-40℃reached 25.5J.
作者
李书成
杨庚蔚
韩汝洋
徐耀文
付至祥
朱晓翔
LI Shucheng;YANG Gengwei;HAN Ruyang;XU Yaowen;FU Zhixiang;ZHU Xiaoxiang(The State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China)
出处
《钢铁》
CAS
CSCD
北大核心
2023年第8期178-185,211,共9页
Iron and Steel
基金
国家自然科学基金资助项目(52204398)
国家重点研发计划资助项目(2017YFB0305100)
湖北省重点研发计划资助项目(2020BAB057)。
关键词
中锰马氏体钢
耐磨钢
终轧温度
晶粒细化
强韧化机制
medium manganese martensite steel
wear-resistant steel
finish rolling temperature
grain refinement
strengthening and toughening mechanism
