Mechanical behavior and fatigue performance of austenitic stainless steel under consideration of martensitic phase transformation

The martensitic phase transformation of the metastable austenitic steel increases yield strength and ultimate stress, but decreases ductility. Evolution of the martensite depends on both plastic strain and stress triaxiality. Experiments at room temperature reveal that the martensitic phase transformation in the austenitic stainless steel 06Cr19Ni10 becomes obvious only for large strains, e.g. >30%. Increasing the material temperature may diminish the phase transformation significantly. By testing specially fabricated specimens, the cold hardening of the material was decomposed into a plastic strain related part and a martensitic phase part. Comparison with experiments confirms that the mechanical behavior of the austenitic-martensitic material can be described by J2 plasticity, combining with the Santacreu model for the phase transformation. Furthermore, the stress-controlled fatigue experiments on the distorted stainless steel display that in the high cycle fatigue regime the plastic strain improves the material's fatigue resistance, while the martensitic phase transformation increases the fatigue property in the finite life regime. However, in the ε-N diagram the benefits from the martensitic phase transformation decrease with loading amplitude and the plastic deformation may reduce fatigue performance. In the LCF region the distorted material shows generally worse fatigue property than the base material.