Abstract
The stress-strain curves of 12 mass% Nickel added steel are investigated at the two temperatures of room temperature and –196 ºC. The stress-strain curves at room temperature after pre-straining at –196 ºC are also compared. The pre-strain at –196 ºC doesn’t induce the strain hardening effect on the yield strength in reloading at room temperature, but increases the flow stress at room temperature. The retained austenite is also measured using XRD and EBSD in the specimens subjected to the different temperature and the straining histories. The flow stress at room temperature after pre-straining at –196 ºC proportionally goes up with an increase of the stress induced martensite. Stability of the retained austenite and hardness of the stress induced martensite are discussed from the viewpoint of local concentration of the austenite former elements.
