The transformation behavior of retained austenite in M2 steel was examined under varying tempering conditions. The steel was initially subjected to interrupted quenching at 105 °C (225 °F), a process that elevated the retained austenite content to approximately 55 vol %, compared to the typical 25 vol % observed after direct quenching to room temperature. This was followed by tempering at 565 °C (1050 °F), without intermediate cooling. Results indicated that double tempering was significantly more effective than single tempering at transforming retained austenite under these conditions. Furthermore, repeated tempering cycles accelerated the complete transformation of retained austenite, achieving full conversion in a shorter total processing time than single-stage tempering.

For more information, click on the link below (subscription required). Then scroll to Figure 5.Jon L. Dossett; George E. Totten, Control of Distortion in Tool Steels, ASM International, 2014 https://doi.org/10.31399/asm.hb.v04d.9781627081689