ABSTRACT
Quench heat treatment is a technologically important process in the manufacturing of metal components. The process involves heating of a metal alloy to an elevated temperature at which microstructurally a single phase is formed and holding at this temperature to obtain a uniform phase throughout the component followed by controlled cooling. The cooling rate or behavior during the quench must be controlled in order to obtain superior mechanical properties with minimal distortion or other ill effects that are inevitable during the quench process. Generally, a liquid quench medium is commonly used to facilitate/control the heat transfer during quenching. The most commonly used quenchants in industries worldwide is water followed by oils. On immersion quenching in these liquids, the metal experiences three typical stages of quenching: vapor stage, nucleate boiling stage, and the convective cooling stage. However, the severity of cooling and the duration of the stages in both classes are very much different. Water, because of its severe nature of cooling, provides ample, or exceeds, mechanical properties over that which is required. Moreover, in many circumstances, such as cooling of complex objects or high-alloyed steels, it causes undue distortion, residual stresses, and, in the most severe case, crack formation. Oils, by their very viscous nature, deliver lower cooling performance and reduces is the propensity towards distortion and cracking. The low quench severity of oils results in reduced properties. These limitations compelled the quenchant suppliers to develop polymer quench media that offer the benefit of both water and oils.
