Experimental identification of flow properties of a S355 structural steel for hot deformation processes

Abstract

A major issue in modeling the dynamics of hot deformation processes is the proper definition of the constitutive law and, therewith, the identification of material parameters. Popular approaches in relating the stress and strain rate values are equations for the power-law and the power-law breakdown regimes. The material parameters of these two models are basically described by a temperature-dependent absolute value, for example, a flow stress, and a strain rate sensitivity being often referred to as power-law exponent or ductility of the material. The current contribution addresses the experimental identification of these two parameters of a S355 structural steel by an innovative testing program on a Gleeble 3500 testing environment. This allows the identification of the hot deformation parameters for a range of temperatures by only one test with varying temperatures. Furthermore, an extrapolation technique is proposed to capture higher strain rate regimes, as occurring in hot deformation processes. A specific application of the material data on basis of a simulated friction welding process demonstrates the scope of the acquired material parameters and concludes the findings of this article.