保温工艺对G20CrNi2Mo轴承钢带状组织的影响  

Effect of heat preservation process on banded structure of G20CrNi2Mo bearing steel

作　　者：韩东 战东平[1] 张洋鹏 姜海昌 戎利建[2] HAN Dong;ZHAN Dong-ping;ZHANG Yang-peng;JIANG Hai-chang;RONG Li-jian(School of Metallurgy,Northeastern University,Shenyang 110819,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]东北大学冶金学院,辽宁沈阳110819 [2]中国科学院金属研究所,辽宁沈阳110016

出　　处：《材料热处理学报》2023年第9期140-149,共10页Transactions of Materials and Heat Treatment

基　　金：中国科学院战略性先导科技专项资助(XDC04010500)。

摘　　要：G20CrNi2Mo轴承钢工件易出现带状组织,降低其疲劳性能和服役寿命。为掌握带状组织的形成原因和消除方法,采用光学显微镜(OM)、扫描电镜(SEM)、电子探针(EPMA)和电子背散射衍射(EBSD)等表征分析了保温工艺对G20CrNi2Mo轴承钢带状组织成分和结构的影响。结果表明:G20CrNi2Mo轴承钢形成带状组织的原因是C元素的偏析,部分区域贫C导致其马氏体相变所需的临界冷却速率增加,随后在锻造冷却时此区域先共析形成了铁素体带;通过高温长时保温可以促进C元素的扩散,进而消除带状组织。对于渗碳/氮热处理过程,当处理温度≥820℃时,带状组织可完全消除。而当处理温度≤820℃时,可通过940℃保温3 h的正火预处理将带状组织提前消除,其在后续的渗碳/氮热处理过程中不再出现。G20CrNi2Mo bearing steel workpieces are prone to form banded structure,reducing their fatigue performance and service life.In order to understand the formation causes and elimination methods of banded structure,the effect of heat preservation process on the composition and structure of the banded structure of the G20CrNi2Mo bearing steel was characterized and analyzed by means of optical microscope(OM),scanning electron microscopy(SEM),electron probe microanalysis(EPMA)and electron backscatter diffraction(EBSD)technique.The results show that the reason for the formation of banded structure in the G20CrNi2Mo bearing steel is due to the segregation of C element.The critical cooling rate required for martensite transformation is increased due to the lack of C in some areas,and then the ferrite band is formed by eutectoid in this area during forging cooling.High temperature and long term holding can promote the diffusion of C element,thereby eliminating banded structure.For the carburizing/nitriding heat treatment process,when the treatment temperature is≥820℃,the banded structure can be completely eliminated.When the treatment temperature is≤820℃,the banded structure can be eliminated in advance by normalizing pretreatment at 940℃for 3 h,and will no longer appear in the subsequent carburizing/nitriding heat treatment process.

关 键 词：G20CrNi2Mo轴承钢 带状组织 保温时间 保温温度 碳氮共渗 

分 类 号：TG142.4[一般工业技术—材料科学与工程]