Heat Transfer Coefficient Determination of Quenching Process

Abstract

Quenching is a widely-known industrial process where a piece at very high temperature is rapidly cooled. Internal modifications of the material and its properties occur during it. The analysis of quenching is relevant in order to characterize the process and, therefore, to tailor the final properties of the treated pieces. Thermal evolution will dictate the type of metallurgical transformations developed and the level of residual stresses and geometrical distortions that the piece will suffer.
Quenching tests are usually performed by instrumenting a probe and quenching it under controlled conditions. As a result, records of temperature evolution inside the probe are obtained. The determination of the total heat transfer coefficient during the quenching test is an ill-posed problem which is usually analyzed through inverse techniques.
In this work, heat transfer coefficient (HTC) is numerically determined for a set of quenching tests. This novel method comprises the use of analytical solutions of a similar problem, direct numerical resolution of the thermal evolution and an iterative algorithm of correction. The conditions of the tests were varied in order to assess the effect of different quenching conditions on the HTC. The physical modeling of different boiling mechanisms is briefly discussed.