Austenitization and carbide dissolution of high speed tool steel AISI-M2 in short time heating

Recently, induction heating treatments have been applied to high alloy tool steels, for example AISI-M2. In rapid and short time heating, however, the influence of heating time and temperature on carbide dissolution and hardness is not fully clarified. The purpose of this study is to make clear the influence of these two factors on carbide dissolution and hardening behavior of AISI-M2 after quenching and tempering. Results obtained are as follows; 1) The initial stage of the holding at austenitizing temperature is characterized by the dissolution of small M6C carbides. 2) Increasing of carbon and alloy elements in matrix before induction heating contributes to the increase in hardness in short time heating. 3) Finally, we applied induction hardening to two sizes of AISI-M2 forming rolls using the fundamental knowledge obtained in this study. Surface hardness is higher than 65HRC and satisfied hardened depth for each sized rolls are obtained.