汽车齿轮渗碳钢热处理过程中的晶粒长大和不均匀性原位观察  

In-situ investigation on grain growth and inhomogeneity in automobile carburized gear steel during heat treatment

作　　者：钟正根[1,2] 莫家璇 刘红亮 张瑞 胡海江 张志成[4] 袁清 Zhong Zhenggen;Mo Jiaxuan;Liu Hongliang;Zhang Rui;Hu Haijiang;Zhang Zhicheng;Yuan Qing(Zhejiang Industry&Trade Vocational College,Wenzhou Zhejiang 325000,China;State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan Hubei 430081,China;Natural Steel Group Co.,Ltd.,Wenzhou Zhejiang 325000,China;Daye Special Steel Co.,Ltd.,Huangshi Hubei 435001,China)

机构地区：[1]浙江工贸职业技术学院,浙江温州325000 [2]武汉科技大学省部共建耐火材料与冶金国家重点实验室,湖北武汉430081 [3]大自然钢业集团有限公司,浙江温州325000 [4]大冶特殊钢有限公司,湖北黄石435001

出　　处：《金属热处理》2025年第4期55-64,共10页Heat Treatment of Metals

基　　金：湖北省自然科学基金联合基金(2024AFD009);湖北省自然科学基金(2024AFB900);国家自然科学基金(52004193)。

摘　　要：采用高温激光共聚焦显微镜对两种不同成分汽车齿轮渗碳钢20CrMnTi在正火-伪渗碳过程中的奥氏体晶粒长大进行原位观察研究,从奥氏体晶粒长大和晶粒不均匀性因子以及第二相颗粒分布来揭示正火-渗碳工艺下的组织演变规律。结果表明,正火-伪渗碳热处理过程中,Nb-Ti-Mo钢奥氏体晶粒尺寸始终要小于Ti-Mo钢,且奥氏体晶粒尺寸不均匀性因子也始终小于Ti-Mo钢,这与其中的(Nb,Ti,Mo)(C,N)颗粒具有较好的抗熟化作用有关。另外,两种钢的奥氏体晶粒尺寸不均匀性因子均随着正火和伪渗碳保温时间的延长而逐渐增大,但伪渗碳过程的奥氏体晶粒尺寸不均匀性因子要略大于正火过程。此外,在伪渗碳阶段,Nb-Ti-Mo钢奥氏体晶粒尺寸不均匀性因子发生急剧增大的情况要晚于Ti-Mo钢。相比于保温时间,奥氏体晶粒尺寸对温度具有更高敏感性,温度的波动容易造成晶粒的明显长大。In-situ observation of austenite grain growth of two automotive gear carburized steels 20CrMnTi with different compositions was studied by using high temperature laser confocal microscope.The austenite grain growth,inhomogeneity factor and second phase particle distribution were discussed to reveal the microstructure evolution during normalizing and pseudo-carburizing.The results show that the austenite grain size of the Nb-Ti-Mo steel is always smaller than that of the Ti-Mo steel during normalizing and pseudo-carburizing,and the austenite inhomogeneity factor of the Nb-Ti-Mo steel is also always smaller than that of the Ti-Mo steel,which is related to the better aging resistance of(Nb,Ti,Mo)(C,N)particles.In addition,the austenite inhomogeneity factor increases gradually with the extension of normalizing time and pseudo-carburizing time,and the inhomogeneity factor during the pseudo-carburizing is slightly larger than that during the normalizing.Moreover,in the pseudo-carburizing stage,the occurrence of the sharp increase in austenite grain size inhomogeneity factor of the Nb-Ti-Mo steel is later than that of Ti-Mo steel.Austenite grain size is more sensitive to temperature than time,and the temperature fluctuation is easy to cause obvious grain growth.

关 键 词：原位观察 微合金化 奥氏体晶粒 析出物 不均匀性因子 

分 类 号：TG142.1[一般工业技术—材料科学与工程]