EBSD texture analysis of a high temperature gas nitrided duplex stainless steel

An electron back scattering diffraction characterization analysis of a high temperature gas nitrided UNS S31803 duplex stainless steel was performed. Nitriding treatments were carried out between 1423 and 1473 K, for times varying between 0.18 and 86.4 ks, under nitrogen partial pressures varying between 0.03 and 0.15 MPa. Upon investigation, these samples displayed a fully austenitic surface layer on a ferritic–austenitic duplex core. The grain boundary character distribution of surface austenitic layers strongly varied as the nitriding parameters were varied; low-ΣCSL grain boundary fractions between 0.35 and 0.65 were obtained. Conversely, the microtexture mainly depended on nitriding time, being only slightly affected by nitrogen partial pressure or temperature changes. At the earliest stages of nitriding, austenitic cases displayed an intense microtexture with two major texture components, {0 0 1}〈1 0 0〉 and {0 1 1}〈2 1 1〉, which weakened as nitriding time was increased.