Improvements in quench factor modelling

In this contribution, the validity of a number of key quench factor analysis (QFA) assumptions is discussed. It is shown that the incorporation of a square root dependency of yield strength on precipitate volume fraction provides a sounder physical basis for quench factor modelling. Peak-aged strength/hardness prediction accuracies are not affected, but C-curve positions are. It is also demonstrated that transformation kinetics are described more correctly by a modified Starink–Zahra equation than by a Johnson–Mehl–Avrami–Kolmogorov type equation, yielding better prediction accuracies when a physically realistic Avrami exponent of 1.5 or greater is used. Finally, a regular solution model is introduced to quantify the influence of the solute solubility temperature-dependency on the minimum strength. These improvements are all implemented within the framework of classical QFA.