Influence of Deformability of Retained Austenite on Martensitic Transformation in Tension for Low Alloy Steel at Low Temperatures

Strain Distribution and Deformation-induced Martensitic Transformation in Tension for a TRIP Steel Plate

“…A sheet-type specimen with a gauge length of 30 mm, width of 4 mm, and thickness of 2.5 mm was cut, so that the longitudinal direction was parallel to the rolling direction (RD). 5) The tensile tests were carried out with an initial strain rate of 2.8 × 10 − 4 s − 1 using a mortar-driven tensile test machine at 293 K (in the air) and 193 K (immersed in a cooling alcohol). The stability of retained austenite depends on test temperature, and we clarified that the decrease of retained austenite with increasing strain was different between these temperatures.…”

“…The stability of retained austenite depends on test temperature, and we clarified that the decrease of retained austenite with increasing strain was different between these temperatures. 5) The effect of the amount of martensitic transformation on strain distribution was discussed through strain distribution analysis was carried out at 293 K and 193 K. The detail tensile properties were reported in our previous study. 5) The cyclically unloaded tests were carried out in steps from 0.04 nominal strain (measured with an extensometer) up to a total of 0.12 nominal strain at 293 K and 193 K. The most of retained austenite transformed to martensite until 0.12 nominal strain.…”

“…5) The effect of the amount of martensitic transformation on strain distribution was discussed through strain distribution analysis was carried out at 293 K and 193 K. The detail tensile properties were reported in our previous study. 5) The cyclically unloaded tests were carried out in steps from 0.04 nominal strain (measured with an extensometer) up to a total of 0.12 nominal strain at 293 K and 193 K. The most of retained austenite transformed to martensite until 0.12 nominal strain. 5) Furthermore, it is difficult to apply DIC analysis to a high strained specimen.…”

“…5) The cyclically unloaded tests were carried out in steps from 0.04 nominal strain (measured with an extensometer) up to a total of 0.12 nominal strain at 293 K and 193 K. The most of retained austenite transformed to martensite until 0.12 nominal strain. 5) Furthermore, it is difficult to apply DIC analysis to a high strained specimen. Therefore, we analyzed strain distribution until the 0.12 nominal strain.…”

“…Furthermore, we have previously demonstrated that the retained austenite near the zone normal to < 111 > along the tensile direction was mechanically stable. 5) Digital image correlation (DIC) has been developed as a conventional strain analysis method, calculating strain from the difference of images before and after deformation. [6][7][8][9] It demonstrates an advantage in application to any strain modes or materials, as long as there is a significant contrast in the digital images.…”