Abstract
Constitutive equations which relate the flow stress to the strain, strain rate, and temperature are useful in metal forming problems and more attractive than experimental data to designers. These equations may be valid only for the range of parameters where actual measurements were made and be inadequate for extrapolation since it is impossible to generalise the validity of these equations for every material. An interpolation scheme (cubic spline fit) used in this study is more satisfactory than the existing constitutive relations used to describe the hot deformation of 99·9% pure aluminium.