奥氏体化温度对51CrVNb弹簧钢组织与力学性能的影响  

Effect of austenitizing temperature on microstructure and mechanical properties of 51CrVNb spring steel

作　　者：曹宇[1] 宋新莉[1] 黄昌虎 贾涓[1] 范丽霞[1] 刘中柱 CAO Yu;SONG Xin-li;HUANG Chang-hu;JIA Juan;FAN Li-xia;LIU Zhong-zhu(State Key Laboratory of Refractory Materials and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,China;CITIC-CBMM Microalloying Center,Beijing 100004,China)

机构地区：[1]武汉科技大学耐火材料与冶金国家重点实验室,湖北武汉430081 [2]中信微合金化技术中心,北京100004

出　　处：《材料热处理学报》2020年第12期97-103,共7页Transactions of Materials and Heat Treatment

基　　金：中信-CBMM基金(2017FWNB-3082)。

摘　　要：为了研究奥氏体化温度与Nb含量对51CrV弹簧钢组织与力学性能的影响,本文以3种不同Nb含量的51CrV弹簧钢为研究对象,并对其进行了800、830、860和900℃奥氏体化1 h后淬火及450℃回火热处理。采用扫描电镜(SEM)、透射电镜(TEM)、能谱仪(EDS)以及万能拉伸试验机等研究了实验钢经不同热处理后的组织、析出相及力学性能。结果表明:3种不同Nb含量的实验钢在800℃奥氏体化,渗碳体没有完全溶入奥氏体。随着奥氏体化温度升高到900℃,不含Nb的实验钢淬火马氏体板条更粗大。淬火实验钢在450℃回火后的组织是回火屈氏体,添加Nb实验钢回火后铁素体基体仍呈板条状,合金碳化物更细小。3种实验钢经不同温度淬火及450℃回火后的屈服强度均大于1300 MPa,但是不含Nb实验钢伸长率小于10%,而添加0.02 mass%Nb实验钢伸长率大于11%。其中含Nb为0.02 mass%的实验钢在860℃淬火及450℃回火后综合力学性能最佳:屈服强度1394 MPa,抗拉强度1452 MPa,伸长率11.38%。In order to study the effect of austenitizing temperature and niobium content on microstructure and mechanical properties of 51 CrV spring steel,three kinds of the 51 CrV spring steel with different niobium contents were studied in this paper,and the steels were subjected to 800℃,830℃,860℃and 900℃austenitizing quenching and 450℃tempering heat treatment.Microstructure,precipitated phase and mechanical properties of the experimental steels after different heat treatment were studied by means of scanning electron microscopy(SEM),transmission electron microscopy(TEM),energy dispersive spectrometer(EDS)analysis and universal tensile testing machine.The results show that the cementite is not completely dissolved into the austenite of three kinds of the 51 CrV spring steel after quenching at 800℃.With the austenitizing temperature increasing to 900℃,the martensite lath sizes of the steel without niobium are coarse.The microstructure of the quenched experimental steel after tempering at 450℃for 50 min is tempered troostite,the ferrite matrix of the experimental steel with Nb addition after tempering is still lath-like,and the carbide precipitates is fine.The yield strength of the three kinds of experimental steel after quenching at different temperatures and tempering at 450℃is more than 1300 MPa,but the elongation of the experimental steel without Nb is less than 10%,while the elongation of the experimental steel with 0.02 mass%Nb added is more than 11%.The experimental steel containing 0.02 mass%Nb has the best comprehensive mechanical properties after quenching at 860℃and tempering at 450℃,and the yield strength is 1394 MPa,the tensile strength is 1452 MPa,and the elongation is 11.38%.

关 键 词：弹簧钢 铌微合金化 奥氏体化温度 力学性能 

分 类 号：TG142.4[一般工业技术—材料科学与工程]