The goal of this project is to improve the fatigue properties of metastable austenitic CrNi steels from the low cycle fatigue (LCF) to the very high cycle fatigue (VHCF) range. The improvement is achieved by a transformation from austenite to deformation-induced martensite through near surface machining processes. Besides surface hardening and the residual stress state, the project examines in detail the microstructural dimensions of the martensite, such as volume fraction, thickness, and distribution. The project quantifies the microstructural parameters through light and electron microscopy as well as X-ray methods, and evaluates their effects by electrical and magnetic in situ measurements.