準安定オーステナイト系ステンレス鋼SUS301LのTRIP効果におよぼすひずみ速度の影響

概要

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In order to investigate the effect of strain rate on TRIP effect in metastable austenitic steels, tensile deformation behavior of a JIS-SUS301L steel was examined at wide range of strain rates between 103/s and 10−3/s, in addition of the comparison with data of stable austenitic steel (JIS-SUS310S). Concerning of the SUS301L steel, the 0.2% proof stress increased and the uniform elongation decreased with increasing of strain rate. The tensile strength decreased with an increase in strain rate between 10−3/s and 101/s and then increased again at strain rate more than 101/s. The significant difference between the strain rate dependences on tensile strength and uniform elongation of SUS301L and SUS310S was clarified especially at strain rates between 10−3/s and 100/s. As far as the effect of strain rate on stress-induced martensitic transformation behaviors is concerned, the volume fraction of stress-induced martensite at the same true strain decreased with increasing of strain rate. These stress-induced transformation behaviors were associated with the tensile strength and uniform elongation of SUS301L steel between 10−3/s and 100/s. The conditions of stress-induced martensitic transformation in order to obtain better uniform elongation at a high strain rate of 100/s were discussed by the calculations using the Weng secant method.