45钢激光氮合金化涂层的组织性能及工艺优化  

Microstructure,properties and process optimization of laser nitrogen alloyed coating on 45 steel

作　　者：李海涛 樊帅奇 张蕾涛 戴姣燕[2] 徐金富 Li Haitao;Fan Shuaiqi;Zhang Leitao;Dai Jiaoyan;Xu Jinfu(School of Materials Science and Engineering,Chang'an University,Xi'an Shaanxi 710061,China;School of Materials and Chemical Engineering,Ningbo Institute of Engineering,Ningbo Zhejiang 315211,China)

机构地区：[1]长安大学材料科学与工程学院,陕西西安710061 [2]宁波工程学院材料与化学工程学院,浙江宁波315211

出　　处：《金属热处理》2021年第8期209-214,共6页Heat Treatment of Metals

基　　金：宁波市2025重大专项(2019B10084);宁波市科技计划(2016B10023)。

摘　　要：利用激光合金化技术在45钢表面制备了氮合金化层,并采用正交试验法优化了合金化工艺参数,采用OM、XRD、显微硬度计和摩擦磨损试验机等手段研究了优化工艺处理后的合金化层的组织及性能。结果表明,随激光功率和扫描速度增大,合金化层硬度呈先增后降的趋势,在1.0 kW和500 mm·min^(-1)时硬度分别达到最大值782 HV0.3和725 HV0.3,随着搭接率的增加,合金化层硬度逐渐下降,其最优工艺为:激光功率1.0 kW、扫描速度500 mm/min和搭接率30%;经最优工艺处理后的合金化区组织由γ-(Fe,N)、γ-(Fe,C)、针状马氏体、γ'(Fe_(4)N)、ε(Fe_(2)N)以及Fe_(3)C等固溶体和化合物组成,以柱状晶和胞状晶为主,厚度约为120μm,平均硬度约为816 HV0.3,热影响区组织由少量针状马氏体以及残留奥氏体等组成,厚度约为200μm,硬度由768 HV0.3到242 HV0.3呈梯度分布;合金化层的摩擦因数约为0.4827,磨损率为8.218×10^(-1)5 m^(3)·N^(-1)·m^(-1)。Nitrogen alloyed layer was prepared on the surface of 45 steel by using laser alloying technology,and the alloying process parameters were optimized by orthogonal test,then the microstructure and properties of the alloyed layer obtained by the optimized process treatment were studied by means of OM,XRD,microhardness tester and friction-abrasion testing machine.The results show that with the increase of laser power and scanning speed,the hardness of alloyed layer increases at first and then decreases,reaching the maximum values of 782 HV0.3 and 725 HV0.3 at 1.0 kW and 500 mm·min^(-1),respectively.With the increase of overlap ratio,the hardness of alloyed layer decreases gradually,and the optimal process is as follows:laser power of 1.0 kW,scanning speed of 500 mm·min^(-1)and overlap ratio of 30%.The microstructure of the alloyed zone after optimized process treatment is composed of solid solution phases and compounds such asγ-(Fe,N),γ-(Fe,C),acicular martensite,γ'(Fe_(4)N),ε(Fe_(2)N)and Fe_(3)C,mainly consisting of columnar and cellular crystals,with a thickness of about 120μm and an average hardness of about 816 HV0.3.The microstructure of the heat affected zone is composed of a small amount of acicular martensite and retained austenite.The thickness is about 200μm,and the hardness is graded from 768 HV0.3 to 242 HV0.3.The friction coefficient of the alloyed layer is about 0.4827,and the wear rate is 8.218×10^(-1)5 m^(3)·N^(-1)·m^(-1).

关 键 词：激光合金化 渗氮 显微硬度 耐磨性 合金化层 

分 类 号：TG174.4[金属学及工艺—金属表面处理]