Influence of Strain Rate on TRIP Effect in SUS301L Metastable Austenite Steel

Abstract

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 10 3 /s and 10 Ϫ3 /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 Ϫ3 /s and 10 1 /s and then increased again at strain rate more than 10 1 /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 Ϫ3 /s and 10 0 /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 Ϫ3 /s and 10 0 /s. The conditions of stress-induced martensitic transformation in order to obtain better uniform elongation at a high strain rate of 10 0 /s were discussed by the calculations using the Weng secant method.

Effects of Temperature and Strain Rate on TRIP Effect in SUS301L Metastable Austenitic Stainless Steel

“…As can be seen, the stress-strain curves and mechanical properties are much more dependent on the temperature than on the strain rate. 1,19,20) Figure 3 shows the true stress and work-hardening rate as a function of the true strain at various temperatures in the SUS301L. The work-hardening rate stopped decreasing and began to increase again below 323 K. Such behavior seems to have led to the changes in the flow curve and tensile properties, as seen in Fig.…”

“…19,20,27) at 296 K. Details of the experimental procedures for tensile tests are described in the references. [18][19][20][21][22]27) In order to investigate the effects of temperature and strain rate on the stressinduced martensitic transformation kinetics, test samples deformed by various amounts of ε were also prepared for xray diffraction analysis. Details of the quantitative estimation of the austenite and martensite phases by x-ray diffraction are also summarized in our previous papers.…”

“…Details of the quantitative estimation of the austenite and martensite phases by x-ray diffraction are also summarized in our previous papers. 19,20) …”

“…Thus far, metastable austenitic stainless steels, 1−14) 9% Ni steels, 15) and TRIP-aided multi-microstructure steels 16−18) have been investigated for TRIP steels. In our previous studies, we investigated the effects of temperature, 19) strain rate 20) and Ni equivalent 21,22) on the TRIP effect and stress-strain curve 22,23) in metastable austenitic stainless steels. In terms of the temperature dependence on the TRIP effect in the SUS304 (Ni equivalent (Nieq.)…”

Effects of Temperature and Strain Rate on Tensile Properties of a Lean Duplex Stainless Steel

“…The XRD experiment procedures are the same as those in previous reports. 11,12) The volume fractions were deduced from the assumption that the sum of the integrated intensities of the diffraction peaks from each phase is proportional to the volume fraction. The volume fraction of stress-induced martensite for the fractured specimens was also calculated in a similar manner.…”