Abstract: The constitutive equation of semi-solid thixoforming is modeled on the basis of combining analysis of deformation mechanism with experimental investigation. The undetermined coefficients in constitutive equation can be achieved by analyzing experimental data and act as the initial value of optimization design. An optimization method for this constitutive equation is discussed. The constitutive equation with optimized coefficients is imported to numerical simulation of isothermal compression of semi-solid Al-4Cu-Mg alloy as a subroutine, thereby obtaining the numerical data of flow stress under several processing conditions. By the aid of this method, geometric effect of deformation can be removed and nature of semi-solid thixoforming described accurately. As a result, the new optimization method of constitutive equation can improve the validity of numerical simulation significantly, which is presented by means of comparing the results of the numerical data with experimental data.

Key words: Constitutive equation, Optimization, Semi-solid, Thixoforming