Constitutive Modeling for Al-Cu-Mg Alloy in Creep Aging Process

The aim of this paper is to develop a set of creep aging constitutive equations for Al-Cu-Mg alloys containing plate- or rod-like precipitates. Average length, aspect ratio and relative volume fraction are introduced to quantitatively analyze the effect of the precipitates of such alloy on creep aging process. The strong interaction between creep deformation and aging treatment is considered by the intermediate state variables of dislocation density and precipitate characteristic dimension. A unified creep aging constitutive equation is derived, in which the correlations between microscopic characteristics and macroperformances of material are linked by the yield strength of the material. Using AA2124 alloy, a series of uniaxial tensile creep tests are carried out at 185A degrees C for 12 h with different stresses. The material constants within constitutive models are determined from the experimental data. A good agreement between experimental and computed values confirms that the established constitutive equations can well characterize the creep behavior.