A novel plasma oxynitriding by using plain air for AISI 1045 steel

Mixed gas source of plain air, nitrogen and hydrogen was primarily used for plasma oxynitriding for AISI 1045 steel, and the effect of air flow on the treating efficiency and corrosion resistance was investigated. The results showed that the amount of air flow was crucial in plasma oxynitriding, and higher efficiency and better corrosion resistance than those for traditional plasma nitriding could be obtained when air flow was appropriately selected. The maximum compound layer thickness of 23 μm was obtained at air flow of 0.2 L/min, almost two times as high as that obtained in traditional plasma nitriding, and corrosion resistance was improved as well. XRD results showed that the oxide formed during plasma oxynitriding was mainly composed of Fe3O4 at suitable air flow, which turned to be Fe2O3 with the increase of air flow, which was the key reason why air flow was crucial in plasma oxynitriding.