Stainless steels are used in various environments due to their excellent corrosion resistance. However, their poor tribological properties limit their range of applications. To overcome these limitations, the low-temperature surface hardening process S³P feat. Kolsterising® can applied. The principle of this treatment is based on the diffusion and interstitial embedding of large quantities of carbon and/or nitrogen into the stainless steel surfaces at temperatures below 500°C. As a result, wear resistance is improved while corrosion performance is maintained. This follow-up study, focused on determining the corrosion resistance limits of Kolsterised samples in chloride media. Initial ASTM G150 tests showed that for several treated materials no breakdown potential could be reached within the standard concentration ranges. Therefore, the chloride concentration was varied to identify the actual corrosion limits of the hardened surfaces, enabling a clearer distinction between the untreated and treated material conditions. The investigated materials include the austenitic S31603, the super-austenitic S31254, the duplex grades S32202 and S32750, and the nickel alloy N08825. The results confirm a significant increase in surface hardness and the formation of a homogeneous diffusion zone (“S-Phase”). The adapted corrosion tests now provide further insights into the corrosion behavior of Kolsterised materials by revealing their performance boundaries in high-chloride environments. To summarize, S³P feat. Kolsterising® significantly improves the surface hardness and abrasion resistance of stainless steels without impairing their corrosion properties. This enables the use of stainless steels in applications where both corrosion and wear resistance are required.
