Effect of Cyclic Heat Treatment on the Hardness and Microstructures of High Carbon Tool Steel

For any tool, abrasion or friction is obvious that causes high wear and ultimately determines its service life. As a result, special focus on the wear resistance of the tool steel is essential. The high wear resistance of tool steel is mostly due to its high hardness achieved by proper heat treatment. In this regard, there is no doubt that alloying elements like Cr, Mn, W, Ni, V, Mo, etc. also play vital roles. However, like alloying elements, final microstructures of tool steels are also very important to ensure the hardness as well as wear resistance. In the case of traditional heat treatment, the steel is heated to a proper austenitizing temperature, soaking there for a predetermined time and quench it into a suitable media. In contrast, in cyclic heating steel is cooled from austenitizing temperature in several steps for modified microstructures. In this study, high carbon tool steel was heat treated by conventional as well as modified cyclic method. After heat treatment, the resulted microstructure and hardness of the heat-treated steel was studied. Experiment results suggest that cyclic heat treatment has a synergistic action in modifying microstructures hence the hardness.