CrWMn钢金相磨制面显微裂纹原因分析  

Analysis of the microscopic crack on the metallographic ground surface of CrWMn steel

作　　者：李平平 刘柯军 LI Pingping;LIU Kejun(CRRC Qishuyan Research Institute Co.,Ltd.,Changzhou,Jiangsu 213011,China;FAW Group Co.,Ltd.,Changchun,Jilin 130000,China)

机构地区：[1]中车戚墅堰机车车辆工艺研究所有限公司,江苏常州213011 [2]中国第一汽车集团有限公司,吉林长春130000

出　　处：《轨道交通材料》2023年第5期7-10,共4页MATERIALS FOR RAIL TRANSPORTATION SYSTEM

摘　　要：对CrWMn钢进行淬、回火处理后磨制金相试样,不同状态下磨制面均可见显微裂纹,通过光学显微镜和扫描电子显微镜观察抛光状态和侵蚀状态下的裂纹形貌,得出以下结论:高碳淬火马氏体尤其在过热淬火状态下,金相磨制面极易产生显微裂纹,随着淬火烈度和过热程度的增加,显微裂纹的数量显著增加;由于放大倍数和衬度等因素,抛光状态下显微裂纹在光学显微镜中不易被发现,须借助扫描电镜在更高倍数下观察;侵蚀状态下显微裂纹易于辨别,其长度与奥氏体晶粒尺寸为同一级别;大多数显微裂纹产生于试样磨制阶段,主要与马氏体的组织敏感性和磨制表面不平衡的收缩有关,但不排除部分裂纹由马氏体针叶相撞所致;淬火试样经中、高温回火后,磨制裂纹数量大幅下降。When grinding CrWMn metallographic specimen after quenching and tempering treatment,microscopic cracks always can be found on the polished surface under different conditions.The following conclusions are drawn after observations of the polished state and the crack morphology under eroded condition with optical microscope and SEM:microscopic cracks can be easily produced on the metallographic ground surface of quenched high-carbon martensitic steel,especially in the overheated quenching state,and with the increase of quenching intensity and the degree of superheat,the quantity of microscopic crack would remarkably increase;the microscopic cracks in polished state could go undetected under optical microscope due to the factors of magnification and contrast,and it should be observed with high power SEM;the microscopic crack in eroded state can be easily identified,and its length is at the same level as that of austenite grain size;the majority of the microscopic cracks occur in the specimen grinding process,which is mainly related to the sensitivity of martensitic structure and the unbalanced shrink of ground surface,of course,some of the cracks could be caused by the collision of martensitic needles;medium and high temperature tempering of the quenched specimen could bring about a sharp decrease in the quantity of ground cracks.

关 键 词：CRWMN钢 高碳马氏体 显微裂纹 过热淬火 组织敏感性 

分 类 号：U270.41[机械工程—车辆工程] TB332[交通运输工程—载运工具运用工程]