超高速激光原位熔覆Ti(C,B)/Ni60A复合涂层的界面特征与表面磨损机理  

Interfacial Characterization and Surface Wear Mechanism of Ti(C,B)/Ni60A Composite Coating Prepared by In Situ Extra High-Speed Laser Cladding

作　　者：徐一斐 张楠 许培鑫 杜博睿 史华 王淼辉 XU Yifei;ZHANG Nan;XU Peixin;DU Borui;SHI Hua;WANG Miaohui(Beijing National Innovation Institute of Lightweight Ltd.,Beijing 100083,China;China Machinery Institute of Advanced Materials Co.Ltd.,Zhengzhou 450001,China)

机构地区：[1]北京机科国创轻量化科学研究院有限公司,北京100083 [2]中机新材料研究院(郑州)有限公司,郑州450001

出　　处：《金属学报》2024年第12期1721-1730,共10页Acta Metallurgica Sinica

基　　金：国家重点研发计划项目No.2021YFB3702003;国家自然科学基金项目No.51975240;北京市自然科学基金项目No.2222093;中国机械科学研究总院集团技术发展基金项目No.812201Q9。

摘　　要：为缓解H13钢表面超高速激光熔覆(EHLA)再制造Ni60A涂层的界面应力梯度,改善涂层的可熔覆性,提升涂层表面的耐磨性,本工作将超高速激光熔覆技术与直接反应合成(DRS)技术相耦合,在H13钢表面成功原位制备出组织均匀、无缺陷的Ti(C,B)/Ni60A复合涂层,并与EHLA制备的Ni60A涂层进行了对比分析。基于纳米压痕的Giannakopoulos&Suresh(G&S)能量法获得了熔覆界面的残余应力分布;利用SEM、EDS、EBSD研究了涂层显微组织、相组成和熔覆界面特征;利用聚焦离子束(FIB)获取了带有涂层表面磨损信息的样品,并采用双球差透射电镜(DSA-TEM)分析了涂层浅表区磨损特征,通过对比显微硬度变化,揭示了Ti(C,B)/Ni60A复合涂层浅表区的磨损机理。结果表明:由于Ti和B4C发生原位反应放出约670 kJ的Joule热影响,Ti(C,B)/Ni60A复合涂层熔覆界面宽度达到22μm,是EHLA制备Ni60A涂层熔覆界面(2μm)的11倍,有效降低了Ti(C,B)/Ni60A复合涂层界面区的应力梯度,缓解了界面两侧的应力失配。然而,获得的Ti(C,B)/Ni60A复合涂层表面硬度仅为360~400 HV0.2,不足Ni60A涂层表面硬度的1/2,而其磨损失重却处于同一量级,这一方面归因于原位自生的大量TiCB相及少量Ti3B4相等支撑Ti(C,B)/Ni60A复合涂层基体,实现减摩耐磨作用;另一方面归因于磨损浅表区180 nm范围内涂层材料在滑擦塑性流变-热-力三场耦合作用下形成了等轴化超细晶粒组织,从而动态强化了磨损表面。H13 die steel easily fails under friction and wear due to its low purity,poor homogeneity,and unreasonable matching between strength and toughness.The preparation of wear-reducing and wear-resistant coatings through extra high-speed laser cladding(EHLA)is important for the restoration and remanufacturing of metallurgical spare parts.This method provides an solution for the in-service life extension of H13 die steel.However,cracking at the EHLA interfaces induced by residual stresses due to low substrate dilution rates,remarkable cooling rates,and differences in thermal expansion between dissimilar metals acts as a limitation to the application of EHLA.This work aimed to alleviate stress mutation at the fusion interface of EHLA coatings,improve the fusibility of EHLA coatings on H13 die steel,and obtain wear-reducing and abrasion-resistant features on the surfaces of EHLA coatings.In this study,a Ti(C,B)/Ni60A composite coating was prepared with almost defect-free microstructures on an H13 die steel substrate by coupling EHLA with direct reaction synthesis to introduce an in situ exothermic reaction into EHLA cladding to achieve the above aims.The obtained material was compared with the pure Ni60A coating prepared through EHLA alone.Residual stress distribution at the fusion interface of the Ti(C,B)/Ni60A composite and Ni60A coatings was determined using the Giannakopoulos&Suresh(G&S)energy method based on nanoindentation.SEM,EDS,and EBSD were performed to investigate the microstructures,phase compositions,and characteristics of the two coatings and cladding interfaces.A focused ion beam setup was used to obtain information on the superficial wear of the two samples,and double spherical aberration TEM was conducted to analyze the superficial wear characteristics of the two coatings.The superficial wear mechanism of the Ti(C,B)/Ni60A composite coating was determined along with the changes in the surface microhardness of the two coatings.Results revealed that the Ti(C,B)/Ni60A composite coating interface was affecte

关 键 词：超高速激光熔覆 复合涂层 残余应力 磨损 原位反应 

分 类 号：TG456.7[金属学及工艺—焊接]