High nitrogen alloying of AISI 316 L stainless steel powder by nitriding

Abstract

Production of bulk high-nitrogen stainless steel components by the powder metallurgy route has gained significant attention lately. This requires the ability to alloy stainless steel powders with significant amounts of nitrogen. This work reports a novel powder nitriding approach to achieve the same. The response of 316 L stainless steel powders to low temperature(425–500 °C) nitriding treatments has been investigated. The nitrided powders have been characterized by Scanning Electron microscopy, X-ray diffraction and Vickers micro hardness measurements. The low temperature nitriding treatments resulted in the formation of a significant nitrided layer, consisting of a Cr-nitride free, expanded austenite phase with large quantities of dissolved nitrogen. The amounts of dissolved nitrogen introduced into the powders have been estimated from XRD based lattice parameter measurements. A maximum nitrogen uptake of 31 at. % could be achieved with an attended hardness of 1750VHN. © 2021 Elsevier B.V.