Microstructural characterization of plasma nitrided austenitic stainless steel

The microstructure of the layers produced by plasma nitriding austenitic st ainless steel at different treatment temperatures (400 and 500 degreesC) we re studied by transmission electron microscopy (TEM) together with X-ray di ffraction (XRD) and scanning electron microscopy (SEM). The results show th at the microstructures were composed of 'expanded austenite' (gamma (N)) an d or(ferrite) + CrN following plasma nitriding at lower and higher treatmen t temperatures, respectively. The former contains stacking faults and defor med twin substructures, while the latter is made up of colonies displaying a lamellar structure. Kurdjumov-Sachs or Nishiyama-Wassermann orientation r elationships between the ct and CrN layer were observed. (C) 2000 Elsevier Science S.A. All rights reserved.