Nb添加和热处理对异质结构高碳钢组织与性能的影响  

Effect of Nb addition and heat treatment on microstructure and properties of heterogeneous high carbon steel

作　　者：赵伟男 卢超 王浩云 曹建春[1] 张永青 周晓龙[1] Zhao Weinan;Lu Chao;Wang Haoyun;Cao Jianchun;Zhang Yongqing;Zhou Xiaolong(Faculty of Materials Science and Engineering,Kunming University of Science and Technology,Kunming Yunnan 650093,China;CITIC Metal Co.,Ltd,Beijing 100004,China)

机构地区：[1]昆明理工大学材料科学与工程学院,云南昆明650093 [2]中信金属股份有限公司,北京100004

出　　处：《金属热处理》2025年第2期133-141,共9页Heat Treatment of Metals

基　　金：国家自然科学基金(52364052);中信金属-CBMM铌技术推广合作项目(2022FWNB-30123(M1162));中信-CBMM铌钢研究与开发项目(2017FWNB-3079)。

摘　　要：针对Fe-0.86%C-0.04%Nb(质量分数)高碳钢进行1150℃淬火和不同温度回火处理,通过OM、SEM、EPMA对不同热处理状态下试样由表及里的组织进行表征,利用维氏硬度计和纳米压痕仪分别进行宏观和微观的硬度测试,并与相同C含量的高碳钢进行对比,研究了Nb对高碳钢组织与性能的影响。结果表明,在高碳钢中加入Nb能减缓淬火加热过程中试样表层C的散逸,同时改变心部C的分布,使表层组织为马氏体和残留奥氏体,心部组织由珠光体、先共析铁素体及少量马氏体构成,由表及里获得异质结构;在回火过程中,Nb促进了细小粒状碳化物的析出。在300℃回火后,含Nb高碳钢试样表层组织为回火马氏体,心部组织为珠光体+铁素体+少量回火马氏体,维氏硬度分别为506 HV0.2和240 HV0.2,表层马氏体和心部珠光体的纳米压痕硬度分别为4.20 GPa和2.42 GPa,表层具有较高的硬度,心部韧性较强,表现出表硬里韧的特征。High carbon steel Fe-0.86%C-0.04%Nb(mass fraction)was quenched at 1150℃and tempered at different temperatures.The microstructure of the high carbon steel specimens under different heat treatment conditions was characterized by means of OM,SEM and EPMA.The macro and micro hardness tests were carried out by using Vickers hardness tester and nanoindentation tester,respectively,and compared with high carbon steel with the same C content.The effect of Nb on the microstructure and properties of high carbon steel was studied.The results show that the addition of Nb in high carbon steel can slow down the dissipation of C at the surface of specimen during quenching,and change the distribution of C at the core.The microstructure at the surface is martensite and retained austenite,and the microstructure at the core is composed of pearlite,proeutectoid ferrite and a small amount of martensite,and the heterostructure is obtained from the surface to the core.During tempering,Nb promotes the precipitation of fine granular carbides.After tempering at 300℃,the microstructure at surface of the high carbon steel specimen containing Nb is tempered martensite,and the microstructure of core is pearlite+ferrite+a small amount of tempered martensite,the Vickers hardness is 506 HV0.2 and 240 HV0.2,respectively,and the nanoindentation hardness of surface martensite and core pearlite is 4.20 GPa and 2.42 GPa,respectively.The surface has higher hardness,and the core has stronger toughness,showing the characteristics of hard surface and tough core.

关 键 词：NB微合金化 异质结构 高碳钢 淬火+回火 表硬里韧 

分 类 号：TG142[一般工业技术—材料科学与工程]