NbC含量对激光熔覆不锈钢涂层组织和性能影响

Effect of NbC Content on Microstructure and Properties of Laser Clad Stainless Steel Coatings

本文采用激光熔覆技术在EA1T车轴钢表面制备了添加不同碳化铌(Nb C)含量的不锈钢涂层。利用X射线衍射仪(XRD)、扫描电镜(SEM)和能量色散光谱(EDS)分析了复合涂层的相结构和显微组织演变,并测定了涂层的硬度和摩擦学性能。结果表明,Nb C的加入起到了细化晶粒的作用,同时在晶间析出Fe(Nb,C)类硬质相。但Nb C的加入会导致涂层中树枝晶的方向性被破坏,但涂层性能增强,且随着Nb C质量分数的增加而提高。特别是当Nb C质量分数为20%时,添加的Nb C全部熔解,然后在晶间析出岛状硬质相。由于Nb C的添加引起细晶强化和弥散强化,显著提高了涂层的硬度和耐磨性。与未加Nb C涂层相比,加入质量分数20%NbC,硬度提高了15%,最高硬度为60HRC。磨损系数显著降低,强化效果最好。20%NbC的复合涂层磨损表面犁沟较浅,磨损机制为磨粒磨损。

In this paper,stainless steel coatings with different NbC contents were prepared on the surface of EA1T axle steel using laser cladding technology.The phase structure and microstructure evolution of the composite coatings were analysed using X-ray diffractometry(XRD),scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS),and the hardness and tribological properties of the coatings were determined.The results show that the addition of NbC plays a role in grain refinement,while Fe(Nb,C)type hard phases are precipitated between the grains.However,the addition of NbC resulted in the disruption of the directionality of the dendrites in the coating,but the coating properties were enhanced and increased with the addition of NbC.In particular,when the mass fraction of NbC is 20%,all of the added NbC melts and then precipitates islands of hard phase between the grains.The hardness and wear resistance of the coating is significantly improved by the fine grain strengthening and diffusion strengthening caused by the NbC addition.The addition of 20%NbC increased the hardness by 15%compared to the uncoated NbC,reaching a maximum hardness of 60HRC;The wear coefficient was significantly reduced to 0.75,with the best reinforcement effect.The wear surface plough furrows of the composite coating with 20%NbC were shallow,and the wear mechanism was abrasive wear.