Dislocation density based model for Al-Cu-Mg alloy during quenching with considering the quench-induced precipitates

The accurate prediction of residual stress for as-quenched Al-Cu-Mg alloy requires profound knowledge on the materials' constitutive behavior. In present work, the flow stress of as-quenched Al-Cu-Mg alloy is modelled using a dislocation density based model which considers the influences of precipitation, solid solution and forest dislocation. The radii and volume fractions of precipitates at different cooling rates and temperatures are predicted by a multi-class precipitation kinetics model. Parameters of the constitutive model are obtained by calibration using isothermal tensile tests. The model predictions are in good agreement with experimental data in terms of the flow stress and volume fraction evolution. The results show that volume fraction of precipitates decreases with the increasing temperature and cooling rate, in contrast to the increasing trend for radius of precipitates. The quench-induced precipitates have an influence only on the magnitudes of flow stress at low temperatures. However, for the large precipitates, the dislocation loops, i.e. geometrically necessary dislocations (GND's), can influence both the strain hardening rates and magnitudes of flow stress.