Constitutive modeling for creep age forming of heat-treatable strengthening aluminum alloys containing plate or rod shaped precipitates

According to recent researches on the strengthening response of aged aluminum alloys, a unified constitutive model has been developed for creep age forming of heat-treatable strengthening aluminum alloys containing plate or rod shaped precipitates. The description of the microstructure evolution has been introduced into this model, including the dislocation density, the size, volume fraction and aspect ratio of precipitates, which correlate with the strengthening response in the creep aging process. Then the yield strength, which could reflect the comprehensive strengthening response of the material, the applied stress and the creep strain constitute the constitutive relation. The introduction of the temperature variable renders this model suitable for different aging temperature. The static aging part of this model was proved to be in good agreement with the evolving character of precipitation and strengthening response. Furthermore, a multi-step fitting process has been applied to determine the material constants in the constitutive equations for an aluminum alloy by experimental results, meanwhile, the computed results tally well with the experimental data. (C) 2012 Elsevier B.V. All rights reserved.