G30Cr15Mo1N高氮马氏体钢的连续冷却相变与强化机制  

Continuous cooling transformation and strengthening mechanism of G30Cr15Mo1N high nitrogen martensite steel

作　　者：李波[1] 陈豪 胡忠会[1] 贾忠宁 陈泽军[2] 曹文全[3] LI Bo;CHEN Hao;HU Zhonghui;JIA Zhongning;CHEN Zejun;CAO Wenquan(The First Aircraft Design and Research Institute of Aviation Industry Corporation of China,Xi’an 710089,Shaanxi,China;School of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;Institute for Special Steels,Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China)

机构地区：[1]中国航空工业集团公司第一飞机设计研究院,陕西西安710089 [2]重庆大学材料科学与工程学院,重庆400044 [3]钢铁研究总院有限公司特殊钢研究院,北京100081

出　　处：《钢铁》2024年第5期116-124,152,共10页Iron and Steel

基　　金：国家重点研发计划资助项目(2016YFB0300101);国家自然科学基金面上资助项目(51871062)。

摘　　要：利用Formastor-F2全自动相变仪测量G30Cr15Mo1N钢的CCT曲线,分析在连续冷却转变过程中高氮钢的组织变化和相转变规律,以指导热处理工艺的制定。另外,还通过XRD、SEM、EDS和TEM等分析方法研究了G30Cr15Mo1N钢在不同回火工艺下组织和力学性能演变,分析细晶强化、固溶强化、位错强化和析出强化对G30Cr15Mo1N钢屈服强度的贡献情况。结果表明,试验钢在实际升温中的Ac1和Ac3温度分别为840和870℃,片层珠光体的转变温度区间为600~700℃,珠光体形成的最快冷速为1℃/s。试验钢在较低温度(≤500℃)回火后微观组织为碳氮化物+回火马氏体+残余奥氏体,整体上保持较高的屈服强度和抗拉强度,分别大于1750和2050 MPa,而伸长率低于3%;在600℃回火后马氏体发生回复再结晶,马氏体板条形貌基本消失,并在TEM试验中观察到尺寸在20~80 nm的短棒状Cr_2(C,N)析出物,这导致高氮钢的强度大幅度下降而塑性得到充分恢复。在150℃回火时,G30Cr15Mo1N钢的屈服强度主要来源于很高的固溶强化和位错强化,其中固溶强化占主要作用;在500℃回火后,位错强化和固溶强化分别降低83.7和249.3 MPa,而析出强化显著增强并产生二次硬化,其主要来源是较高比例尺寸小于10 nm析出相。而当回火温度高达600℃时,固溶强化、位错强化、第二相强化均大幅度下降,且对屈服强度的贡献较为均衡,共同起到了重要的强化作用。The CCT curve of G30Cr15Mo1N steel was measured by Formastor-F2 automatic phase transformation instrument,and the microstructure change and phase transformation of high nitrogen steel in the process of continuous cooling transformation were analyzed to guide the formulation of heat treatment process.In addition,the microstructure and mechanical properties of G30Cr15Mo1N steel at different tempering temperatures were studied by XRD,SEM,EDS and TEM characterization methods,and the strength contributions of grain size,solid solution,dislocation and precipitation to the yield strength of G30Cr15Mo1N steel was analyzed.The results show that the Ac1 and Ac3 temperatures of the experimental steel are 840 and 870°C respectively,the temperature range of lamellar pearlite transformation is 600-700°C,and the fastest cooling rate of pearlite formation is 1°C/s;After tempering at a lower temperature(≤500℃),the microstructure of the experimental steel is composed of carbon nitride,tempered martensite,and remained austenite,and maintains high yield strength and tensile strength,exceeding 1750 and 2050 MPa,respectively,while the elongation is less than 3%;after tempering at 600℃,the martensite recovers and recrystallizes,and the strip shape of martensite plate basically disappears.A short rod like Cr2(C,N)precipitate with the size of 20-80 nm was observed in the TEM,which led to a significant decrease in the strength of high nitrogen steel and a full recovery of plasticity.When tempered at 150°C,the yield strength of G30Cr15Mo1N steel mainly comes from high solid solution and dislocation strengthening,among which solid solution strengthening plays a major role;after tempering at 500°C,the strength contributions of dislocation and solid solution respectively decrease 83.7 and 249.3 MPa,the main source of the significant secondary hardening effect is a higher proportion of precipitates with a size smaller than 10 nm.When the tempering temperature is as high as 600°C,the solid solution,dislocation,and second phase stren

关 键 词：高氮马氏体钢 连续冷却转变 回火 显微组织 强化机制 

分 类 号：TG142.24[一般工业技术—材料科学与工程]