0.4C-1.5Si-1.2Mn鋼のTRIP効果におよぼすひずみ速度の影響

概要

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Effect of strain rate on mechanical properties and TRIP effect on TRIP-aided multi-phase steel obtained by 0.4C-1.5Si-1.2Mn steel (0.4C TRIP steel) was investigated by tensile tests with strain rates between 3.3×10−6 s−1 and 103 s−1 at room temperature. The 0.4C TRIP steel showed good uniform elongation at low strain rates below 10−3 s−1 due to TRIP effect and tensile strength increased with an increase in strain rate. The strain rate dependence on stress-induced martensitic transformation was also investigated by x-ray diffraction experiments at strain rates between 3.3×10−5 s−1 and 100 s−1. These results clearly show the stress-induced transformation should be induced momentarily by straining at the latter stage of deformation in order to obtain larger uniform elongation. By comparing the experimental results between the 0.4C TRIP and the metastable austenitic steels, it is found that the volume fraction of retained austenite and the stability of ausutenite are associated with the difference of the strain rate dependence on TRIP effect.