Model for commercial 6XXX series aluminium alloys age-hardening simulation

The aim of the paper is to present a quantitative physically based model for age-hardening behavior simulation of Al-Mg-Si alloys with major alloying elements content in practically interesting range: 0.7 wt. %< Si, Mg < 1.2 wt. %. Aging alloy microstructure evolution due to precipitate particles nucleation, growth and coarsening is described with the help of numerical approach based on classical nucleation-growth equations. Concurrent formation of two types of precipitate particles (Guinier-Preston zones and beta"-phase particles) is taken into account. Calibration of the model was performed mainly on the basis of a broad experimental data on quenched alloys isothermal aging kinetics investigation by Young's modulus, yield stress and electrical resistance measurements. At the first step of model calibration self-consistent sets of physical parameters that control nucleation and growth processes for both types of precipitate particles (activation energies of diffusion, specific energies of particle-matrix interfaces, precipitate solvent temperatures and others) were obtained using experimental data on Young's modulus increment. Quantitative evaluation of these parameters was performed using original procedure specially developed for this purpose. At the second step additional parameters of age-hardening response sub-model were determined. At the final step the model parameters, which appeared to be dependant on chemical composition, are presented as simple empirical functions of the composition. The developed model is capable to predict with reasonable accuracy solution treated Al-Mg-Si alloys age-hardening behavior under simple isothermal and different multi-step (non-isothermal) aging treatments, including initial natural pre-aging of the material, in practically interesting range of the main alloying elements content.