Constitutive equations for high temperature flow stress of aluminium alloys

Constitutive equations for the relationship between stress, strain, strain rate, and temperature are an essential input for modelling thermomechanical processing. Hot plane strain compression testing was used to deform commercial purity aluminium, Al-1Mn, and Al-1Mg alloys at temperatures of 300, 400, and 500 degrees C and equivalent strain rates of 0.25, 2.5, and 25 s(-1), to an equivalent strain of 2. Flow stress data obtained from these tests were analysed using the Sah et al, and hyperbolic sine forms of relationships. Values of constants in the constitutive equations were obtained and were shown to provide an accurate description of the experimental stress-strain curves, including the effect of temperature rise due to deformational healing and the effect of changing strain rate. The application and limitations of the relationships are discussed. (C) 1997 The Institute of Materials.