High Temperature Deformation Constitutive Equation of Metal Materials Based on Deformation Eigenvalues and Characteristic State Parameters

A constitutive equation for high temperature deformation of metal materials, including high temperature deformation process equation and characteristic parameter equation, was established based on the deformation eigenvalues (σ_ss,σ_p,ε_p,ε_r) and characteristic state parameters (LM, Z, erf, MTS). By the high temperature compression test of commercial pure aluminum, oxygen free copper and ultra-low carbon steel, the calculation accuracy of the constitutive equation was verified. The results show that the high temperature deformation results of pure aluminum and ultra-low carbon steel calculated by the constitutive equation were in agreement with the test results. The relative error between the calculated values and the test values of the peak stress of pure aluminum and ultra-low carbon steel was less than 10%, while that of oxygen free copper was up to 15%, indicating that the calculation accuracy of oxygen free copper was slightly lower. The constitutive equation can be used to predict the flow stress of pure aluminum and ultra-low carbon steel under the condition of hot working deformation.