Vickers Hardness Properties of Austenitic Stainless Steels from Cryogenic Temperatures to Room Temperatures

In this study, hardnesses measurements were carried out for austenitic stainless steels (JN1, JN2, SUS304 and SUS316L) from 4K in liquid helium to 293K in room temperature. Hardness increases with a decrease in temperature to around 70K. After peaking, the hardness increases again below 70K. Applying the Arrhenius equation to the hardness properties, two different deformation processes are suggested: slip dislocation at higher temperatures and deformation twinning at lower temperatures. The temperature of the peak hardness changes with loading rate. This temperature change corresponds to the change in the intersection between twin stress and slip stress with the loading rate. As a result, it is clear that a change in the deformation mechanism from slip dislocation to deformation twinning occurs.