2.25Cr-1Mo-0.25V钢中黑色组织的形成机制及消除  

Formation mechanism and elimination of black structure in 2.25Cr-1Mo-0.25V steel

作　　者：杜军毅 朱永有 蒋中华[2] 段红玲 Du Junyi;Zhu Yongyou;Jiang Zhonghua;Duan Hongling(Erzhong(Deyang)Heavy Equipment Co.,Ltd.,Deyang Sichuan 618000,China;Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang Liaoning 110016,China)

机构地区：[1]二重(德阳)重型装备有限公司,四川德阳618000 [2]中国科学院金属研究所沈阳材料科学国家研究中心,辽宁沈阳110016

出　　处：《金属热处理》2023年第9期271-278,共8页Heat Treatment of Metals

摘　　要：通过对大型2.25Cr-1Mo-0.25V钢锻件黑色组织的微区化学成分、光学和SEM显微组织分析研究,确定了“黑色组织”为M_(23)C_(6)“碳化物聚集区”。通过“黑色组织”演化规律的验证,找到了其形成机制和锻件低温冲击性能偏低和离散的根本原因。其形成机制与锻态钢中晶界处富集的M_(23)C_(6)碳化物有关;淬火后,在晶界上形成大尺寸的M-A岛,高温回火后,M-A岛分解、转变成聚集M_(23)C_(6)碳化物。基于形成机制并通过工艺试验,进一步发现实施≥940℃退火预处理可以消除“黑色组织”,重新热处理后锻件的各项力学性能指标均显著提高。Through analyzing the micro-area chemical composition,optical and SEM microstructure,the “black structure” of large 2.25 Cr-1Mo-0.25V steel forgings was studied.The results show that it is “M_(23)C_(6) carbide accumulation area”.By verifying its evolution law,it is found that the “black structure” is the root cause of relative low and scattered low temperature impact property of the forgings,and its formation mechanism is related to the formation of large block M-A islands at grain boundary during quenching and then decomposing and transforming into carbide accumulation during tempering at high temperature tempering,while the formation of large block M-A islands is caused by the accumulated M_(23)C_(6) carbides existed in the as-forged steel.Through the process test and based on its formation mechanism,it is further found that the “black structure” can be eliminated by annealing pretreatment above 940 ℃,and the mechanical properties of the forgings after reheat treatment are significantly improved.

关 键 词：2.25CR-1MO-0.25V钢 黑色组织 碳化物 M-A岛 

分 类 号：TG157[金属学及工艺—热处理]