Microstructural characterization of plasma nitrided austenitic stainless steel

The microstructure of the layers produced by plasma nitriding austenitic stainless steel at different treatment temperatures (400 and 500°C) were studied by transmission electron microscopy (TEM) together with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the microstructures were composed of ‘expanded austenite’ (γN) and α(ferrite)+CrN following plasma nitriding at lower and higher treatment temperatures, respectively. The former contains stacking faults and deformed twin substructures, while the latter is made up of colonies displaying a lamellar structure. Kurdjumov–Sachs or Nishiyama–Wassermann orientation relationships between the α and CrN layer were observed.