Fernandes, Frederico Augusto Pires1; Christiansen, Thomas Lundin1; Somers, Marcel A. J.3
1 Department of Mechanical Engineering, Technical University of Denmark2 Materials and Surface Engineering, Department of Mechanical Engineering, Technical University of Denmark3 Centre for oil and gas – DTU, Center, Technical University of Denmark
Low temperature thermochemical surface hardening of the precipitation hardening austenitic stainless steel A286 in solution treated state was investigated. A286 contains, besides high amounts of Cr, also substantial amounts of strong nitride formers as Ti, Al and V. It is shown that simultaneous surface hardening and bulk hardening is possible and that high treatment temperatures can be applied, provided that the nitrogen activity in the imposed gas phase is low. Expanded austenite is shown to be stable even at temperatures as high as 500°C; this is ascribed to the presence of Ti.