Cincinnati Steel Treating

Hardening-Quench and Tempering Applications

Steel is considered hardened when it undergoes the austenite-to-martensite solid state phase transformation. This is accomplished by heating the steel part above the austenite transformation temperature and then quenching it in a fast cooling medium such as water, oil, or air. The strengthening

occurs when the microstructure changes from austenite to martensite. Martensite is a meta-stable phase that has a greater strength and hardness compared to either room temperature ferrite or high temperature austenite. The degree of strengthening in the martensite is dependent upon the carbon content of the steel. The hardening/quench and tempering operation is finished when the part is heated to an intermediate .