Tool Steels: Forging Simulation and Microstructure Evolution of Large Scale Ingot

The aim of this paper is to analyze the hot working behavior of two different steels based on 3% and 5% Cr steel chemistry, respectively. Hot deformation is studied by hot torsion tests in the range of temperatures 1000-1200°C and strain rates 0.01, 0.10, 1.00 $s^{-1}$. At given temperatures and strain rates flow curves exhibit a peak followed by a decline towards a steady state which is indicative of dynamic recrystallization. At constant strain, flow stress increases with increasing strain rate and decreasing temperature. The analysis of the constitutive equation relating peak flow stress, strain rate and temperature shows high activation energy values for both steels. Recrystallized volume fraction of steels after hot deformation is estimated based on the grain orientation spread as measured by electron backscattered diffraction technique, on the hot deformed and quenched materials.