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Q195 steel was treated with titanizing followed plasma nitriding by glow plasma alloying technology using single pulse power supply. The corrosion resistances of titanizing sample and titanizing + ion nitrided sample were studied. The results show that the alloying layer is 200 μm in depth and organization is α-Fe solid solution containing Ti by plasma titanizing technology using single pulse power supply. An obvious reactive diffusion dividing line formed between alloying layer and the substrate. It shows that diffusion phenomenon happened in process of titanizing. The morphology of Ti alloy layer was columnar crystals. The content of Ti on the surface is up to 5 wt%. And the Ti content of alloying layer is in a decreasing from the surface to the inner on a gradient distribution. The phase structure of titanizing layer is composed of Fe2Ti, Fe-Ti and TiC phases. The phase structure of titanizing + ion nitrided sample was obviously TiN phase and a few Fe-Ti phase. The surface hardness of untreated carbon steel is 110 HV and that of the alloying layer of titanizing is 310HV. The surface hardness of titanizing + ion nitrided sample is 1800HV. The corrosion resistance of titanizing sample is increased 12.15 times compared with the untreated sample and 1.42 times compared with 18-8 stainless steel in H2SO4solution; The corrosion resistance of titanizing + ion nitrided sample is increased 7.444 times compared with the untreated sample and as well as 18-8 stainless steel in H2SO4solution.

Q235 steel was processed by solid carburizing and quenching after conducted by W-Mo-Y double glow-discharge plasma surface alloying process. Finally carbon contents, the morphologies and phases of the samples' surface were analyzed. The results show as follows: Carbon contents of the samples' surface are 1.28 wt%, 1.36 wt%, 1.51 wt% respectively after W-Mo-Y alloying layer (also called co-penetrated layer) was processed by solid carburizing at 960 °C, 980 °C, 1020 °C respectively; The amount of the carbides in W-Mo-Y alloying layer is obviously more than that of the carbides in W-Mo alloying layer; The granular carbides distribute dispersively and uniformly in alloying layer, and the sizes of carbide particle are less than 1 μm; There is no eutectic carbide at the grain boundaries; With temperatures of carburizing and quenching process rising, the carbides increases in number; After W-Mo-Y alloying layer was carburized and quenched at 1020 °C, the phases of alloying layer are Fe2C, W2C, Fe2MoC, MoC, Fe3C, Mo2C and Y2C3; and the types of their carbides are M3C, M2C, and MC, which are different from the types of W-Mo carbides in general metallurgy high-speed steel (HSS). It can be seen from the available, the morphologies, the sizes and the amount of surface HSS's carbides can be adjusted by heat treatment.

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In this study, TiN coatings were deposited on 201 stainless steel by multi-arc ion plating (MAIP). The effect of negative bias voltage on the surface microstructure, hardness, phase structure and the corrosion resistance of the coatings were investigated by SEM, hardness instrument, XRD and electrochemical measurement. The number and size of droplets decreased when the negative bias voltage increased from -100 V to -300 V. But when the substrate bias increased to a certain value, there were some pits appeared. The hardness increased at first and decreased later with the increasing of the negative bias voltage. When the negative bias voltage was -200 V, the hardness was the highest. The intrinsic hardness of TiN film was 2195HV. In 3.5% NaCl solution, the corrosion resistance of TiN coatings samples were improved slightly compared with 201 stainless steel. In l mol/L H2SO4 solution, the corrosion resistance of -100V sample was the best, the corrosion resistance of -100V coating sample was increased 486 times compared with untreated 201 stainless steel.