Study Of Fabrication Processes, Structure And Properties Of Chromized Layer On Stainless Steel Surface By Cathodic Arc

Plasma chromizing technology can effectively improve the surface hardness andwear resistance of stainless steel while the corrosion resistance is not decreased, butthe study of cathodic arc plasma chromizing process on austenitic stainless steelsurface has not be reported yet. In this work, the chromized layers were obtained bycathodic arc plasma alloying on the surface of AISI316L stainless steel. Themorphology, compositions, phase structure, microhardness, friction, and wearresistance of the samples were investigated using scanning electron microscope,3Dsurface profilometer, X-ray diffraction equipment, auger electron spectroscope,microhardness tester, the ball-plate friction and wear testing machine. The influenceof diffusion period, duty ratio, and bias voltage on the structure and properties of thechromized layer was investigated. The results are as follows:（1） The surface hardness of the316L stainless steel sample is increased due tothe precipitation of Cr₇C₃in the chromized layer. With increasing diffusion period,the depth, surface chromium content, and surface roughness of the chromized layerare increased. The depth of chromized layers obtained by chromizing for2h and4hwere57nm and150nm respectively. The friction coefficients and wear rates aredecreased as the diffusion period is increased.（2） With the increase in duty ratio, the depth of the chromized layer, the contentof Fe-Cr intermetal compound in the chromized layer as well as the hardness of thesamples are increased, while the friction coefficients and wear rates are decreased.When the unipolar pulse bias voltage with a duty ratio of70%or direct current bias isused, the depth of the chromized layer and the surface hardness of the sample areapproximately18μm, and320³40HV, respectively. The wear rate of the sampleprepared under the duty ratio of70%is the lowest, which is about1.3×10^-14m³.N^-1m^-1.（3） With the rise of bias voltage, the depth of chromized layer, the content ofFe-Cr intermetal compound, the surface roughness of the chromized layer areincreased. When the bias voltage is800V,900V and1000V, the depth of the chromized layer is about15μm,18μm and42μm respectively. When the biasvoltage is increased from700V to1000V, the surface microhardness is increasedfrom180HV increased to370HV, and the wear rate of the samples is decreasedfrom1.91×10^-14m³.N^-1.m^-1down to1.35×10^-14m³.N^-1.m^-1. The friction coefficient ofthe samples prepared with bias voltage of900V and1000V, is about0.19.