铁素体不锈钢激光熔覆层组织和性能研究

采用无碳合金粉末和低碳合金粉末对铁素体不锈钢进行激光表面熔覆处理,借助光学显微镜(Optical microscope,OM)、扫描电子显微镜(Scanning electron microscopy,SEM)、能谱分析仪(Energy dispersive spectrometry,EDS)、X射线衍射仪(X-ray diffractometry,XRD)、显微硬度仪、摩擦磨损试验仪、电化学工作站对熔覆层显微组织、化学成分、硬度、耐磨性和耐蚀性进行评价。结果表明,两种激光熔覆层均无裂纹、气孔等宏观缺陷,显微组织主要由等轴晶、包状晶、树枝晶和枝间共晶组成。无碳熔覆层与低碳熔覆层均含有α-Fe、Fe-Cr合金相、Cr单质相以及Cr_(9.1)Si_(0.9)、Fe_(9.7)Mo_(0.3)、Fe_(10.8)Ni、Fe_(19)Mn等金属间化合物。此外,低碳熔覆层还产生了间隙化合物Cr_7C_3以及马氏体相C_(0.055)Fe_(1.945)。低碳熔覆层硬度为750 HV0.5,显著高于母材硬度250 HV0.5;无碳熔覆层硬度为650 HV0.5,其热影响区发生软化。激光熔覆层相对于母材具有更为稳定的摩擦特性以及优异的耐磨性和耐蚀性,其中低碳熔覆层耐磨性和耐蚀性均优于无碳熔覆层。

Microstructure and Properties of Laser Cladding Layer on Ferritic Stainless Steel

Cladding coatings are fabricated on the surface of 0Cr13 ferritic stainless steel by laser cladding with no-carbon and low-carbon alloy powder respectively. The microstructure, phases and properties including micro-hardness, abrasive resistance and corrosion resistance of the cladding layers are investigated by optical microscope(OM), scanning electron microscopy(SEM), energy dispersive spectrometry (EDS), X-ray diffractometry(XRD), friction and wear tester and electrochemical workstation. The results show that these two kinds of alloy powder form good cladding layers without defects such as cracks and pores. The microstructures of the cladding layers mainly consist of equiaxed grain, cellular crystal, dentrite and interdendritic eutectic. The common phases of the two cladding layers areα-Fe、Fe-C、Cr、Cr9.1Si0.9、Fe9.7Mo0.3、Fe10.8Ni and Fe19Mn. Besides, interstitial compound phase Cr7C3 and martensite phase C0.055Fe1.945 are observed in the low-carbon cladding layer. The low-carbon cladding layer with a hardness of 750 HV0.5 shows the highest wear resistance and electrolytic corrosion resistance in comparison with the 0Cr13 matrix with a hardness of 250 HV0.5 and the no-carbon cladding layer with a hardness of 650 HV0.5. Softening occurred at the heat affect zone (HAZ) of no-carbon cladding layer. Both of the two cladding layers show a more stable frictional characteristic compared with matrix.