Significant progress has been achieved in recent years in the mathematical modelling of hot working processes, especially with the application of finite element modelling to the heterogeneous deformation of steel. The project aims to develop constitutive equations which relate morphological and constitutional features of the transformed microstructures to the state of the prior austenite and the cooling rate. The programme will entail carrying out detailed metallography on a series of controlled-rolled C-Mn and HSLA steels, and relating the microstructural observations to the prediction of the improved finite element model.