Characterization of 316L Stainless Steel Surface-Modified with Laser Cladded Co-9Al-12W Alloy Coatings

The surfaces of 316 L stainless steel,an automobile material,were modified with Co-9 Al-12 W alloy coatings deposited by laser cladding.The influence of the laser cladding conditions,including the feed-rate of alloy powder,power/energy-density/scanning-speed of laser beam,on the microstructures,tribological behavior and interfacial adhesion was investigated with X-ray diffraction,scanning electron microscopy,energy dispersive spectroscopy and electrochemical analysis.The results show that the Co-9 Al-12 W alloy coatings,synthesized under the optimized conditions,significantly improved the tribological properties of 316 L stainless steel.For example,the dense and compact Co-9 Al-12 W cladding zone(CZ),comprising the columnar,cellular,columnar dendritic,and interdendritic eutectic grains,mainly in γ-Co and Al23 C6 phases,had an average micro-hardness of 586.5 HV 0.3,2.8 times higher than that of the substrate.The corrosion resistance against salt-haze was also considerably increased.We found that as the dilution rate decreased,the micro-hardness increased.