Prediction of mechanical properties of heavy forgings

This paper deals with the problem of forging of heavy parts. The stock material for this process has the microstructure of the casted material, which is characterised by strong inhomogeneity of grains and the presence of pores. This structure is altered during forging by subsequent processes of plastic deformation and recrystallization. Therefore, the problem of penetration of plastic deformation inside the forging becomes essential. The general objective of the work is an evaluation of the minimum reduction of the cross-section of the forging, which still allows the required mechanical properties to be obtained. The research included both experimental tests and finite-element simulation of the forging process. The tested material was middle carbon steel containing 0.4% C and 1.3% Mn. The experiments consisted of the measurement of yield stress, tensile strength and hardness for samples cut from various parts of the forging. The results were compared with the local values of strains and temperatures during the forging process predicted by the finite-element program. The microstructure evolution models were implemented into the finite-element code, which allowed the prediction of distributions of grain size in the volume of the forging. Analysis of all the results allowed conclusions to be drawn regarding a design of forging technology that will guarantee required properties of forging. (C) 1998 Elsevier Science S.A. All rights reserved.