Precipitation of chromium nitride nano-rods on lamellar carbides along austenite-ferrite boundaries in super duplex stainless steel

In super duplex stainless steel, austenite-ferrite boundaries are preferential sites for the precipitation of chromium nitride (Cr2N) during heat treatment. In this study, we observed a large number of Cr2N rods were continuously lined up on a thin lamella of M23C6 of 20 nm width along an austenite-ferrite boundary. This observation indicates that M23C6 carbides at the boundary play a significant role in promoting the formation of Cr2N rods. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.