Microstructure and microtexture changes during solution nitriding to produce austenitic case on ferritic-austenitic duplex stainless steel

The present paper reports an investigation into the microstructural changes occurring in a ferritic-austenitic duplex stainless steel during solution nitriding. Both microstructure and microtexture modifications as a result o f nitrogenation have been studied, in addition to the interaction between s olution nitriding, grain growth, and texture. Three microstructural zones w ere identified. a duplex ferrite-austenite region overlayed by a transition zone overlayed again at the surface by an austenitic zone. The solution ni triding led to nitrogen enrichment at the specimen surface, which in turn e nlarged the austenitic field in this region. The ferrite dissolution here t riggered secondary recrystallisation, accompanied by a texture change. Henc e, the texture of the austenite in this region was different from that in t he duplex region. MST/4297.