Stress state and strain rate dependence of the strain-induced martensitic transformation in a metastable austenitic stainless steel

The strain-induced martensitic transformation in a metastable austenitic stainless steel is investigated by high-energy x-ray diffraction and material modeling. Two different deformation modes are used (cold rolling and uniaxial tensile loading) and the effect on the strain-induced martensitic transformation behavior is investigated. Moreover, three different strain rates during the uniaxial tensile loading are evaluated. The results show a sigmoidal transformation behavior of the strain-induced martensite in respect to true strain, for tensile loading. The effect of different strain rates is also clearly seen and it alters both the amount of transformed martensite and the transformation behavior. The martensite transformation is drastically decreased already at moderate strain rates such as 10-2 s-1, due to adiabatic heating of the sample. The material model used gives an accurate prediction of the strain-induced martensitic transformation behavior during tensile loading. This is valuable for further implementation of the current material model in industrial forming mulations of real components.Godkänd; 2007; 20071212 (pethed)