Powder metallurgy is one of the promising techniques for producing different metals and their alloys. The uniqueness of this technique owes to its processing parameters that can be optimized to produce a desired material with tailored physical and mechanical properties. Among the available biomaterials, the austenitic stainless steel 316L has been used for some time for manufacturing implants and other surgical devices. However, this material is prone to localized corrosion attacks. It corrodes in human physiological conditions in long-term applications and releases metal ions. The corrosion products include ions of nickel, chromium and iron that accumulate in the tissues surrounding the implant limiting its usage as a biomaterial. This research work aims diffusing a sintering gas (nitrogen) into the matrix of stainless steel by increasing the dwell time. The results of the study show that the increased dwell time not only diffuses nitrogen into the matrix but also forms a protective layer of nitrogen onto the samples surface. There is also a notable effect of increased dwell time on the densification and microhardness of the sintered samples. The results indicate that this surface layer can prevent the leaching of metal ions from the stainless steel matrix. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2020.