CFD Investigation of Quench Media and Orientation Effects on Structural Stress Induced in the Intense Quenching Processes for Aluminum Cylinder Heads

Heat treatment is a common manufacturing process in automotive industries to produce high performance components such as cylinder heads and cylinder blocks. Although heat treatment incorporating a quenching process, either by high velocity air flow or water, can produce parts with durable mechanical properties, an unwanted effect of intense quenching processes is that they also induce thermal residual stress, which often is a leading cause for quality issues associated with high cycle fatigues. During product development cycle, it is not uncommon to switch between air and water quench media and change quench orientation in order to minimize residual stress. However, the choice of quench media and quench orientation is often determined by intuitive engineering judgement at the best and trial-and-error iterative method at the worst. With the advancement of CFD technologies, the temperature profile and history of quenching processes now can be accurately calculated. Since thermal residual stress is directly linked to non-uniform temperature distribution in the metal, spatial temperature gradient of each quenching process is evaluated to study and compare the performance of different quench media and configuration. The conclusion of this study can be used to establish engineering guidelines for future product development.