淬火、回火对连铸QTNi4MoV球墨铸铁组织和硬度的影响  

Effect of quenching and tempering on microstructure and hardness of QTNi4MoV ductile iron prepared by continuous-casting

作　　者：颜国君[1] 张欣昱 美小煜 王锦涛 王文城 薛琦 刘保建 蒋百铃 YAN Guo-jun;ZHANG Xin-yu;MEI Xiao-yu;WANG Jin-tao;WANG Wen-cheng;XUE Qi;LIU Bao-jian;JIANG Bai-ling(School of Materials Science and Engineering,Xi’an University of Technology,Xi’an 710048,China;Equipment and Project Management Center,Army Equipment Department of PLA,Beijing 100072,China)

机构地区：[1]西安理工大学材料科学与工程学院,陕西西安710048 [2]陆军装备部装备项目管理中心,北京100072

出　　处：《材料热处理学报》2024年第4期140-151,共12页Transactions of Materials and Heat Treatment

摘　　要：采用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)和硬度计等对QTNi4MoV球墨铸铁在淬火和回火过程中的组织及硬度变化规律进行了研究。结果表明:经1323 K保温4 h的石墨化退火处理后,QTNi4MoV球墨铸铁的组织由石墨球+残留奥氏体+针状贝氏体组成,硬度约为40 HRC;再经1223 K保温1 h油淬后,QTNi4MoV球墨铸铁的组织由石墨球、马氏体和残留奥氏体组成,硬度为48.5 HRC;淬火后QTNi4MoV球墨铸铁的组织具有良好的回火抗力,回火温度达到773 K时,其淬火马氏体才开始分解;经773 K保温3 h的一次和二次回火后,QTNi4MoV球墨铸铁的组织为石墨球、回火马氏体和少量残留奥氏体,硬度值分别为47.5和46 HRC,抗拉强度高于900 MPa,满足铝合金压铸模具服役时对其制造材料在力学性能方面的要求。Microstructure and hardness changes of QTNi4MoV ductile iron during quenching and tempering were studied by means of optical microscope(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and hardness tester.The results show that after graphitizing annealing treatment at 1323 K for 4 h,the microstructure of the QTNi4MoV ductile iron consists of graphite balls,retained austenite and acicular bainite,with a hardness of about 40 HRC.After holding at 1223 K for 1 h and oil quenching,the microstructure of the QTNi4MoV ductile iron is composed of graphite balls,martensite and retained austenite,with a hardness of 48.5 HRC.After quenching,the microstructure of the QTNi4MoV ductile iron has good tempering resistance,and when the tempering temperature reaches 773 K,the quenched martensite begins to decompose.After primary and secondary tempering at 773 K for 3 h,the microstructure of the QTNi4MoV ductile iron is composed of graphite,tempered martensite and a small amount of retained austenite,the hardness values are 47.5 and 46 HRC,respectively,and the tensile strength is higher than 900 MPa,meeting the mechanical performance requirements for the manufacturing materials of aluminum alloy die-casting molds during service.

关 键 词：QTNi4MoV球墨铸铁 淬火 回火 显微组织 硬度 

分 类 号：TG143.5[一般工业技术—材料科学与工程]