Characteristic study and comparison of different hardening methods on low-alloy medium-carbon spring steel

Heat treatment is an operation or combination of different operations involving heating and cooling of solid metal to alter its properties. In addition to other properties, the mechanical properties of steel decide its applicability for a particular condition. Heat treatment processes are commonly used to enhance the required properties of steel. The required property enhancement may be due to change in existing room temperature phase or chemical composition change with or without the phase changes or controlled phase transformation coupled with strain hardening induced by intentional mechanical deformation. The present work aims at experimentally investigating the effects of Conventional Hardening, Austempering and Martempering on AISI 4137 steel. AISI 4137 steel is low alloy, medium carbon spring steel. Experimental investigation shows that as bought steel is least hard, martempered and conventionally hardened steels are hardest. An increase in brittleness is observed with the increase in hardness, with the conventionally hardened specimen displaying the least impact strength.