Solid State Phase Transformation Mechanism in High Carbon Steel Under Compressive Load and with Varying Cr Percent

Low alloyed High carbon steels with duplex (DHCS)s structure of martensite and retained austenite (RA) have considerable potential for industrial application in high abrasion environments due to their hardness, strength and low cost. Using standard compression testing, XRD, nano-indentation, EBSD and TEM, we determined the mechanical stability of RA in DHCS under compressive stress and recognized the phase transformation mechanism, from the macro to the nano level. We found that at the initial stage of plastic deformation both BCT and HCP martensite formation takes place, whereas higher compression loads trigger BCT martensite formation. The combination of this phase transformation and strain hardening is able to increase the hardness significantly. We also investigated the effect of Cr on the transformation behaviour, hardness and mechanical stability of RA with varying Cr contents. Increasing Cr% increased the stability of retained austenite, consequently, increased the critical pressure for martensitic transformation.