Thermal spraying of a nitrogen alloyed austenitic steel

Stainless steel coatings provide an alternative to protect steel surfaces against corrosive attack. The 316 L stainless steel coatings have been conventionally produced by different spraying processes for such applications. Because the nitrogen alloyed stainless steels exhibit not only superior mechanical properties, but also better corrosion behaviour than conventional stainless steels, in this study the coatings of a nitrogen alloyed austenitic steel were produced using a high velocity oxy-fuel (HVOF) spraying process and an atmospheric plasma spraying (APS) process. Due to much stronger deformation strengthening, the coatings deposited by the HVOF spraying process presented a much higher microhardness than the coatings deposited by the APS process. Moreover, the coatings deposited by the HVOF spraying process were also more corrosion resistant than the coatings deposited by the APS process, because the oxidation of the powder material during HVOF spraying was much lower than that during APS. Compared with the coatings of the conventional stainless steel 316 L, the nitrogen alloyed steel coating deposited by the HVOF spraying process showed a much better corrosion performance.