UHSLC制备M2涂层微观组织与界面应力  

Microstructure and interfacial stress of M2 coating prepared by UHSLC

作　　者：张楠 徐一斐 杜博睿 王淼辉 ZHANG Nan;XU Yifei;DU Borui;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：《焊接学报》2024年第10期88-96,共9页Transactions of The China Welding Institution

基　　金：国家重点研发计划资助项目(2021YFB3702003);国家自然科学基金资助项目(51975240);北京市自然科学基金资助项目(2222093)。

摘　　要：利用超高速激光熔覆(ultra-high speed laser cladding,UHSLC)技术在42CrMo钢基体表面制备了M2高速钢涂层.采用扫描电子显微镜(scanning electron microscopy,SEM)、电子背散射衍射(electron backscatter diffraction,EBSD)、能谱仪(energy dispersive spectrometer,EDS)、X射线衍射仪(X-ray diffraction,XRD)和透射电子显微镜(transmission electron microscopy,TEM)对M2涂层的微观组织结构进行了研究.结合原子力显微镜(atomic force microscopy,AFM)对纳米玻氏压痕的投影接触面积进行了测量和修正计算,并获得了M2涂层沿截面厚度方向的残余应力分布.结果表明,UHSLC制备的M2涂层稀释率较低,与42CrMo钢基体形成了宽度约为1^(2)μm的熔覆界面,界面冶金结合良好.靠近熔覆界面的M2组织形貌以等轴状为主,中间区呈现大量片状马氏体组织,浅表区由晶内纳米级针状马氏体+晶界“篮网”状晶界碳化物组成.“篮网”状碳化物主要为非稳态V_(4)C_(3)和非稳态Cr_(3)(W_(10)C_(3))_(2),且相互符合[5 15 3]_(V_(4)C_(3))‖[110]_(Cr_(3)(W_(10C_(3)))_(2))和(015)_(V_(4)C_(3))‖[1 15]_(Cr_(3)(W_(10C_(3)))_(2))的平行位相关系.修正计算了pile-up引入的压头接触投影面积,所获得的M2熔覆界面残余应力信息与G&S(Giannakopoulos&Suresh)能量法吻合度较高.当M2熔覆界面位置的残余拉应力达到约300 MPa的峰值后,在42CrMo钢热影响区内呈现应力陡降并随后进入压应力状态.The M2 HSS coating was prepared on the surface of 42CrMo steel substrate using ultra-high speed laser cladding(UHSLC).The microstructure and characteristics of the M2 coating were investigated by scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),energy dispersive spectrometer(EDS),X-ray diffraction(XRD)and transmission electron microscopy(TEM).The projected contact area of Bohrer-nanoindentation was measured and corrected to calculate in combination with atomic force microscopy(AFM),and the residual stress distribution of the M2 coating in the direction of thickness was obtained.The results showed that the M2 coating prepared by UHSLC had a low dilution rate and formed a cladding interface with a width of about 1^(2)μm,and the interface metallurgy was well bonded.The M2 microstructure near the interface was predominantlv equiaxial,with a large amount of lamellar martensite in the intermediate zone,and the subsurface zone consisted of intracrystalline nano scale acicular martensite+grain boundary"basket net"-like carbides.The"basket net"-like carbides were composed of unstable V_(4)C_(3) and unstable Cr_(3)(W_(10)C_(3))_(2),in accordance with parallel orientation relationships of[5 15 3]_(V_(4)C_(3))‖[110]_(Cr_(3)(W_(10C_(3)))_(2))and(015)_(V_(4)C_(3))‖[1 15]_(Cr_(3)(W_(10C_(3)))_(2)),The projected contact area of Bohrer-nanoindentation introduced by pile-up was corrected and the obtained information on residual stresses at the M2 cladding interface was in good agreement with the G&S(Giannakopoulos&Suresh)energy method.After the residual tensile stress near the M2 cladding interface reached a peak value of about 300 MPa,it showed a steep decrease in stress within the heat affected zone(HAZ)of the 42CrMo steel and subsequently entered the compressive stress state.

关 键 词：超高速激光熔覆 显微组织 残余应力 纳米压痕 

分 类 号：TG456.7[金属学及工艺—焊接]