基于23MnNiMoCr54钢复杂显微组织和表面脱碳演变规律的退火条件控制  

Annealing Condition Control Based on the Evolution of Complex Microstructure and Surface Decarburization in 23MnNiMoCr54 Steel

作　　者：赵帆 胡昊[1,2] 刘雅政 张志豪[1,2] 谢建新 ZHAO Fan;HU Hao;LIU Yazheng;ZHANG Zhihao;XIE Jianxin(Institute for Advanced Materials and Technology,University of Science and Technology Beijing,Beijing 100083,China;Key Laboratory for Advanced Materials Processing(MOE),University of Science and Technology Beijing,Beijing 100083,China;School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学新材料技术研究院,北京100083 [2]北京科技大学材料先进制备技术教育部重点实验室,北京100083 [3]北京科技大学材料科学与工程学院,北京100083

出　　处：《材料导报》2022年第1期126-131,共6页Materials Reports

基　　金：中国博士后科学基金(2019TQ0031);中央高校基本科研业务费(FRF-TP-20-030A1)。

摘　　要：轧材显微组织特征和表面脱碳是高强度矿用圆环链钢质量控制的关键,对矿用圆环链的编链、焊接、热处理、预拉伸工序乃至服役性能有着重要影响。本实验研究了退火温度和气氛对矿用高强度圆环链钢23MnNiMoCr54轧材硬度、显微组织和表面脱碳的影响。研究结果表明,在660~710℃退火后,退火前的马氏体、贝氏体分别转变为回火索氏体、退火态贝氏体,碳化物球化程度提高,轧材硬度较退火前显著降低,并且随退火温度升高,硬度也逐渐降低。在720~730℃退火后,出现由粗大马氏体、铁素体、少量碳化物组成的异常组织,轧材硬度较高。另一方面,随着退火温度由660℃升高至730℃,表面脱碳层深度逐渐增加;退火温度升高至700℃以后,表面脱碳层深度随温度升高增加较快。在710℃退火时,随着氧气体积浓度由21%降低至约0%,表面脱碳层深度逐渐减小;当氧气浓度降低至5.25%以下后,直边位置不再产生表面脱碳。23MnNiMoCr54轧材的退火温度应控制在680~700℃,为尽量减少表面脱碳,可考虑将退火炉内的氧气体积浓度控制在5%以下。The microstructure characteristics and surface decarburization are crucial to the quality control of high strength mining round-link chain steel 23MnNiMoCr54 and have an important effect on the subsequent bending,welding,heat treatment,prestretching processes and service performance of mining round-link chains.This paper reported the effect of annealing temperature and atmosphere on harndess,microstructure and surface decarburization of 23MnNiMoCr54 rolled bars.After annealing in temperature range of 660—710℃,the martensite and bainite transform into tempered sorbite and annealed bainite,respectively.The spheroidization degree of carbide is improved,and the hardness of rolled bar decreases significantly.In addition,with the increase of annealing temperature,the hardness of rolled bar also decreases.After annealing in temperature range of 720—730℃,the abnormal microstructure is composed of coarse martensite,ferrite and a small amount of carbides,resulting in a relatively high hardness of rolled bar.In the meanwhile,with the annealing temperature increasing from 660℃to 730℃,the surface decarburization depth increases with a sudden increasing at 700℃.With the oxygen concentration decreasing from 21%to about 0%,the surface decarburization depth after annealed at 710℃decreases significantly.When the oxygen concentration is below 5.25%,the surface decarburization at straight edge is eliminated.The annealing temperature of 23MnNiMoCr54 rolled bars should be controlled in the temperature range of 680—700℃.In order to reduce the surface decarburization as much as possible,the oxygen concentration should be controlled below 5%.

关 键 词：矿用圆环链钢 退火 硬度 显微组织 表面脱碳 

分 类 号：TG161[金属学及工艺—热处理]