球阀表面渗碳凹坑及黑斑产生原因  

Causes of carburized pits and black spots on the surface of ball valve

作　　者：于艳敏 车鹏程 刘青 YU Yanmin;CHE Pengcheng;LIU Qing(Harbin Songlin Power Station Equipment Co.,Ltd.,Harbin 150046,China;Harbin Energy Innovation Digital Technology Co.,Ltd.,Harbin 150028,China;Academy of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China;Harbin Boiler Co.,Ltd.,Harbin 150036,China)

机构地区：[1]哈尔滨松林电站设备有限公司,哈尔滨150046 [2]哈尔滨能创数字科技有限公司,哈尔滨150028 [3]哈尔滨工业大学材料科学与工程学院,哈尔滨150001 [4]哈尔滨锅炉厂有限责任公司,哈尔滨150036

出　　处：《理化检验（物理分册）》2023年第3期45-49,共5页Physical Testing and Chemical Analysis(Part A:Physical Testing)

摘　　要：某火电厂用316L钢球阀在表面渗碳热处理后产生凹坑及黑斑现象,严重影响了球阀使用过程中的密封效果。采用宏观观察、扫描电镜及能谱分析等方法,分析了该凹坑及黑斑的产生原因。结果表明:球阀在渗碳过程中,温度和热处理时间控制不当,导致表面碳元素形成局部偏聚,形成了局部黑色区域;Cr元素在表层区域形成短程扩散,并覆盖于表层,渗碳后以M_(23)C_6和Fe-Cr-C化合物相形式析出,M_(23)C_6以球状形式偏聚,随着运行过程发生脱落,并形成凹坑,元素在凹坑边缘偏聚并析出有害相,析出和脱落交替作用,最终导致凹坑加速形成。The surface of 316L steel ball valve used in a thermal power plant produced pits and black spots after carburizing heat treatment,which seriously affected the sealing effect of the ball valve during use.The causes of the pits and black spots were analyzed by means of macroscopic observation,scanning electron microscopy and energy spectrum analysis.The results show that the improper control of temperature and heat treatment time in the carburizing process of ball valve results in the formation of local segregation of surface carbon elements and the formation of local black areas.The Cr element formed a short-range diffusion in the surface area and coverd the surface layer.After carburization,it precipitated in the form of M_(23)C_6 and Fe-Cr-C compound phase.M_(23)C_6 segregated in spherical form and fell off with the operation process,and formed pits.The elements segregated at the edge of the pits and precipitated harmful phases.The precipitation and falling off alternate,and eventually led to the accelerated formation of pits.

关 键 词：球阀 渗碳热处理 凹坑 黑斑 元素偏聚 

分 类 号：TB31[一般工业技术—材料科学与工程]