工程机械用超高强钢的直接淬火-回火工艺及组织性能  

Direct-quenching and tempering process and microstructure-property of ultra-high strength steel for construction machinery

作　　者：郑东升 范才河[1] 周顺志 董跃 夏毅 Zheng Dongsheng;Fan Caihe;Zhou Shunzhi;Dong Yue;Xia Yi(College of Materials and Advanced Manufacturing,Hunan University of Technology,Zhuzhou Hunan 412007,China;Teaching Affairs Office,Hunan University of Technology,Zhuzhou Hunan 412007,China)

机构地区：[1]湖南工业大学材料与先进制造学院,湖南株洲412007 [2]湖南工业大学教务处,湖南株洲412007

出　　处：《金属热处理》2025年第3期51-57,共7页Heat Treatment of Metals

基　　金：国家自然科学基金(52271177);湖南省科技创新领军人才项目(2021RC4036);国家级大学生创新创业训练计划(S202311535033);湖南省自然科学基金(2025JJ70040,2025JJ70063)。

摘　　要：借助MMS-200热模拟试验机、光学显微镜(OM)、扫描电镜(SEM)和维氏硬度计研究了830℃热变形后的冷速(2~20℃/s)、回火温度(150~600℃)对直接淬火工程机械用超高强钢微观组织和硬度的影响,并对比了直接淬火-回火工艺和再加热淬火-回火工艺下的微观组织和硬度。结果表明,随着热变形后冷速的增大,粒状贝氏体、上贝氏体消失,自回火马氏体的含量降低,冷速超过5℃/s时,微观组织为板条马氏体和自回火马氏体的混合组织;试验钢的硬度逐渐增加,冷速为20℃/s时,硬度最大,为509 HV。试验钢直接淬火-回火后,随着回火温度的升高,碳化物的析出位置从马氏体板条内过渡到原始奥氏体晶界和马氏体板条界上,并不断聚集、粗化;试验钢的硬度逐渐减小,当回火温度为150℃时,硬度最大,为510 HV。相同回火工艺下,相较于再加热淬火-回火试验钢,直接淬火-回火试验钢中的马氏体板条宽度更小,基体的硬度更高。Effects of cooling rate(2-20℃/s)after hot deformation at 830℃and tempering temperature(150-600℃)on the microstructure and hardness of direct-quenched ultra-high strength steel for construction machinery were studied by MMS-200 thermomechanical simulator,optical microscope(OM),scanning electron microscope(SEM)and Vickers hardness tester,and the microstructure and hardness of the steel under direct quenching and tempering process were compared with that under reheated quenching and tempering process.The results show that granular bainite and upper bainite disappear and the content of auto-tempered martensite decreases with the increase of cooling rate after hot deformation,and the microstructure is a mixture of lath martensite and auto-tempered martensite when the cooling rate exceeds 5℃/s.As the cooling rate increases,the hardness of the tested steel gradually increases,and the maximum hardness is 509 HV at the cooling rate of 20℃/s.When the tested steel is directly quenched and tempered,with the increase of tempering temperature,the precipitation position of carbides transits from the inside of martensite lath to the prior austenite grain and martensite lath boundaries,and the carbides continuously aggregate and coarsen.The hardness of the tested steel decreases with the increase of tempering temperature,and the maximum hardness is 510 HV at the tempering temperature of 150℃.Compared with reheated quenched and tempered steel,the width of martensite lath in direct quenched and tempered steel is smaller,and the hardness of matrix is higher under the same tempering process.

关 键 词：工程机械用超高强钢 冷却速度 直接淬火 回火温度 微观组织 

分 类 号：TG113.251[金属学及工艺—物理冶金]