0.2C-1.5Si-1.2Mn鋼のTRIP効果におよぼすひずみ速度の影響

Abstract

Effect of strain rate on tensile properties and stress-induced martensitic transformation behavior in a 0.2C-1.5Si-1.2Mn (0.2C TRIP) steel was investigated at strain rates between 3.3×10–6 s–1 and 103 s–1. The 0.2% proof stress and tensile strength increased and uniform elongation decreased with an increase in strain rate in the 0.2C TRIP steel. At low strain rates below 10–4 s–1, the 0.2C TRIP steel was obtained good uniform elongation. In the strain-rate dependence on stress-induced martensitic transformation behavior, the volume fraction of stress-induced martensite decreased at strain rates higher than about 10–2 s–1 due to the temperature rise caused by adiabatic deformation. The difference of stress-induced transformation behavior between the 0.2C and 0.4C TRIP steels seems to be associated with the stress partitioning to retained austenite. Furthermore, the stress partitioning is affected by the volume fraction of not only retained austenite but also ferrite and bainite.