Electronic impact of concentrated interstitial carbon on physical properties of AISI-316 austenitic stainless steel

Abstract

Applying low-temperature carburization to foils of AISI-316 austenitic stainless steel, we obtained precipitate-free solid solutions of interstitial carbon in austenite with uniform, constant carbon levels ≈0.1, orders of magnitude above the equilibrium solubility limit. In this study, we report the impact of such concentrated interstitial carbon on the mass density, electrical conductivity, thermal conductivity, conduction electron concentration, and electron mobility. Compared to the as-received state, the carburized material only has 0.9 of the mass density, 0.8 of the electrical conductivity, and 0.7 of the thermal conductivity. Hall-effect data indicate that the reduced conductivity is not caused by reduced electron mobility, but exclusively by reduced conduction electron concentration. These observations suggest that the interstitial carbon atoms form covalent bonds with the transition metal atoms. With their unique combination of properties, free-standing uniform concentrated solid solutions of interstitial carbon in austenite, realized here in the form of fully low-temperature-carburized foils, can be regarded as a new material that warrants further studies.