A New Constitutive Model for Hot Forging of Steels Taking Into Account the Thermal and Mechanical History

The paper presents a new constitutive model which accurately describes the rheological behaviour of steels in hot bulk metal forming operations both in single- and multi-step deformation conditions. In the proposed formulation the effects on the flow curve of all the significant phenomena accompanying the deformation process are accommodated and the previous thermo-mechanical history is represented through the average austenitic grain size measured immediately before the deformation. The number of coefficients to be evaluated is reasonably restricted and the testing required to this aim not too complex.