Experimental identification and validation of the plastic wave approach in hot forging of steels

The accuracy of forging simulations depends on a lot of parameters. Among them, the tool/workpiece behaviour has a crucial importance. The present paper deals with the processing of experimental data from a versatile friction test device which allows the recording of experimental normal and drag forces on the actual workpiece surface. Tests can be carried out for various sliding velocities, tool and workpiece temperatures, contact pressure, etc. The processing procedure is described and the corresponding new theoretical developments are presented. Three friction laws are identified: Tresca, Coulomb and plastic wave model. Comparisons for hot forging of steels are made with both analytical models and numerical 2D finite element modelling. Analytical models are based on the same theoretical tools as those used for the plastic wave friction model. Two descriptions of the tool/workpiece interface are considered: a macroscopic and a mesoscopic one.