High corrosion resistance performance of 304 stainless steel after liquid nitrocarburization

304 stainless steel is widely used in many industrial fields, however, poor wear resistance of H2S limited its applications. In this study, novel composites coatings were deposited onto stainless steel surface by a liquid nitrocarburization technique. XRD, EMPA, SEM were conducted to investigate the surface modification of 304 Austenitic Stainless Steel after liquid nitrocarburization for 8 h at 703 K (430 °C). Wear test results showed that the wear resistance of nitrocarburized 304 stainless steel was increased in comparison with the non-nitrocarburized one. The corrosion potential was investigated by standard saturated hydrogen sulfide gas. And the results indicated that the austenite transformed into the S phase after forming supersaturated solid solution of N on the surface and kept intact after corrosion test. The corrosion current density was clearly reduced. Low diffusion coefficient of hydrogen atoms in S-phase reduced the possibility of environmental cracking of H2S and improved the H2S corrosion resistance of after liquid nitrocarburization.