Prediction of quenching-induced stress distribution in 7XXX aluminium alloy thick plates using Gleeble interrupted quench tests

In the fabrication of heat treatable aluminum parts for the aeronautic industry, quenching is a key step to obtain the required mechanical characteristics after aging. For thick plates, thermal gradients cause non-homogeneous plastic strain resulting in residual stresses (RS) after quenching. In 7xxx alloys, precipitation phenomena may affect these RS. Quenching RS are extensively reduced by stress relief. However, RS at final temper could lead to some distortions during machining of large and complex parts. For their prediction, it is thus important to be able to model the full process and particularly the quenching. In this work a simple but realistic approach is presented to predict as-quenched RS. Instead of modeling precipitation, yield strength is characterized with a few Gleeble interrupted quench tests. The results are introduced in a finite element model and predictions are compared to residual stress measurements in plates of different thicknesses for two different 7xxx alloys.