Tribological properties of stainless steels treated by colossal carbon supersaturation

A promising, alternative surface treatment to traditional case carburizing was recently developed. It enables extremely high ('colossal') supersaturation of carbon (up to 12 at.%) in austenitic stainless steel surfaces. This new treatment offers the advantage of hardening the surface while still retaining the corrosion resistance of stainless steels. In this study, the tribological properties of the colossal supersaturation carburized Type 316 stainless steel were investigated and benchmarked against non-treated steel. The carburized surfaces exhibited higher hardness, higher elastic modulus, and higher resistance to acid etching than non-treated surfaces. Hot hardness measurements were conducted and linear relations between the hardness and temperature were observed for both treated and non-treated specimens. The friction and wear characteristics were evaluated at both room and elevated temperatures (200 and 400 °C) under non-lubricated sliding conditions (pin-on-disk). Additional room-temperature tests were performed in salt water. Improved wear-resistance was observed on the treated surfaces at all test conditions, though less benefit was observed at elevated temperatures or in salt water.