Influence of γ‐α′‐Phase Transformation in Metastable Austenitic Steels on the Mechanical Behavior During Tensile and Fatigue Loading at Ambient and Lower Temperatures

Abstract The present investigation is concerned with the three metastable austenitic steels AISI 304 (X5CrNi1810), 321 (X6CrNiTi1810), and 348 (X10CrNiNb189). In the temperature range −60 °C ≤ T ≤ 25 °C tensile and fatigue tests were performed to characterize the mechanical and phase transformation behavior using stress‐elongation, stress–strain hysteresis, and magnetic measurements. The mechanical properties are significantly influenced by the temperature dependent deformation induced phase transformation from austenite to α′‐martensite which are combined with pronounced hardening processes. Furthermore microhardness measurements after fracture could be correlated with the results of the fatigue tests.