Effects of local material properties on the deformation behaviour of austenitic steels in the context of hydrogen environment embrittlement

In this work, the formation and properties of microsegregations, as well as the influences of segregation-induced variations of material properties on the deformation behaviour and hydrogen-induced damage of austenitic CrNi steels were investigated. It was shown that segregations have a significant influence on local austenite stability and local variations of austenite stability control the formation of deformation-induced α-martensite. The resulting α-martensite provides favourable conditions for the formation and growth of hydrogen-induced cracks, thereby increasing susceptibility to embrittlement. Investigations into the hydrogen embrittlement of austenitic CrMnCN steels showed that they have a high susceptibility to embrittlement despite a stable austenitic microstructure. This could be explained by the deformation behaviour of these steels, which is based on planar dislocation sliding and the formation of twins.