Hardening and tempering of engineering steels is performed to provide components with mechanical properties suitable for their intended service. Steels are heated to their appropriate hardening temperature (800~900 celsius), held at temperature, then quenched often in oil.
This is followed by tempering which develops the final mechanical properties and relieves stresses. The actual conditions used for all three steps are determined by steel composition, component size and the properties required.
Hardening and tempering develops the optimum of hardness, strength and toughness in an engineering steel and offers the component designer a route to savings in weight and material. Components can be machined or formed in a soft state and then hardened and tempered to a high level of mechanical properties.
