Mechanical Properties of Nitrogen Alloyed Metastable Austenitic Stainless Steels

摘要

Strain induced matensitic transformation and its effect on mechanical properties of low nickel austenitic stainless steels during deformation was investigated. Such phase transformation were measured by ferritescope and X-ray diffraction (XRD). The data on strain induced matensite transformation can be fitted by Olson-Cohen formula very well. The transformation is in the sequence of austenite(γ)→mechanical twin(γ')→-α'-martensite when a cold rolling is adapted as the deformation method. The tensile stress-strain curves is sigmoid due to formation of ot'-martensite after a critical strain. Strain induced martensitic transformation during the tensile test can lead to an increase in the ultimate tensile strength, ductility and toughness, particularly the working hardening rate. Moreover, yield strength is linearly dependent on by strain-induced martensite fraction.