激光表面强化对40CrNiMo钢组织及性能的影响  

Effect of Laser Surface Strengthening Technology on Properties and Microstructure of 40CrNiMo Steel

作　　者：廖金雄 陈金友 LIAO Jin-xiong;CHEN Jin-you(Hunan Financial and Industrial Vocational-Technical College,Hengyang Hunan 421002,China;Tianjin University of Technology and Education,Tianjin 300222,China)

机构地区：[1]湖南财经工业职业技术学院,湖南衡阳421002 [2]天津职业技术师范大学,天津300222

出　　处：《材料保护》2021年第5期144-149,共6页Materials Protection

基　　金：湖南省自然科学基金项目(2017JJ5006)资助。

摘　　要：为了提高常见汽车传动轴的耐磨性及力学性能,分别采用激光淬火及激光熔覆技术对40CrNiMo钢表面进行了激光强化处理。利用金相显微镜、扫描电子显微镜(SEM)观察了试样的微观形貌;利用显微硬度计测试了淬火试样的硬度;利用高低温摩擦磨损试验机测试了淬火试样的摩擦磨损性能;利用万能力学试验机对熔覆层的力学性能进行了评估。结果表明:40CrNiMo钢经激光淬火后,表面出现一层相变硬化区,深度约为300μm,硬度值最高可达815.6 HVH_(2N),约为基体的3.2倍;平均摩擦系数0.391,与传统淬火工艺相比下降了42.8%,磨损量1.4 mg,降低了56.3%;主要磨损机制由疲劳磨损和黏着磨损转变为磨粒磨损,耐磨性得到较大改善。40CrNiMoA钢经激光熔覆后,表面光滑平整,合金熔覆层与基体能够形成冶金结合,其抗拉强度、屈服强度、延伸率分别为981 MPa、716 MPa、19.1%,断裂机制以韧性断裂为主,材料的强度和塑性均得到改善。In order to improve the wear resistance and mechanical properties of common automobile transmission shafts,laser quenching and cladding technology were used respectively to strengthen the surface of 40 CrNiMo steel.The microscopic morphology of the sample was observed by metallographic microscope and scanning electron microscope(SEM).The hardness of the quenched layer was measured by microhardness tester.The friction and wear properties of quenched samples were tested by high and low temperature friction and wear testing machine.The mechanical properties of the cladding layer were evaluated by universal mechanical testing machine.Results showed that after laser quenching of 40 CrNiMo steel,a transformation hardened zone appeared on the surface with a depth of about 300μm and a maximum hardness of 815.6 HVH_(2N),which was about 3.2 times that of the matrix.The average friction coefficient was 0.391,which was 42.8%lower than the traditional quenching process,and the wear amount was 1.4 mg,which was reduced by 56.3%.The main wear mechanism changed from fatigue wear and adhesive wear to abrasive wear,and the wear resistance was greatly improved.After laser cladding treatment of 40 CrNiMoA steel,the surface was smooth and flat,and the alloy cladding layer formed a metallurgical bond with the substrate.Its tensile strength,yield strength and elongation were 981 MPa,716 MPa and 19.1%,respectively,the fracture mechanism was dominated by ductile fracture,and both strength and plasticity of the material were improved.

关 键 词：40CRNIMO钢 激光表面强化 激光淬火 激光熔覆 组织 性能 

分 类 号：TG142.1[一般工业技术—材料科学与工程]