Controlled Quenching of Aluminum Alloys In Flexible Nozzle Fields for the Reduction of Distortion

During heat treatment of age hardenable aluminum alloys the resulting mechanical properties can be particularly influenced by the quenching process. To achieve the required strength, a high efficient cooling rate after solution annealing is necessary. In order to avoid distortion, a homogeneous distribution of quenching intensity should be realized. Controlled quenching within heat treatment process of aluminum components can be realized by flexible nozzle fields. Suitable heat transfer conditions of the aluminum components are realized by flexible flow fields (local and/or temporal) based on simulation of flow field by CFD. By the use of gas-(air), spray-(water/air) or jet-(water) flow fields it is possible to adapt the quenching intensity to the component geometry thereby controlling the mechanical properties as well as the workpiece distortion after heat treatment. For this purpose a flexible nozzle field quenching process was integrated into heat treatment for age hardening of different wrought-, cast-, and spray-formed aluminum alloys. In this contribution the process outline for spray quenching of aluminum specimen will be introduced. Results for aluminum specimen quenching in spray fields will be discussed. The effect of quenching process parameter of the aqueous and air phase will be determined through hardness measurements on the aluminum specimen. Furthermore, the distortion of asymmetrically quenched specimen through the usage of flexible nozzle fields will be discussed. A spray characterization as well as measurements through infrared thermography were performed on aluminum specimen to provide experimental data for the implementation of specific local heat transfer conditions into the CFD heat transfer simulations.