Hot workability of as-cast Fe₃Al-2.5%Cr intermetallic alloy

Abstract

Processing characteristics of as-cast Fe₃Al-2.5%Cr alloy have been studied using constant strain rate isothermal compression tests in the temperature range 1023-1323 K and strain rate range 0.001-10 s⁻¹. At strain rates ≤0.1 s⁻¹, the stress–strain curves are of steady-state type while at higher strain rates the flow stress reaches a peak before falling into either a steady-state or continuous flow softening with strain. The processing map of the alloy revealed a domain of dynamic recrystallization (DRX) at temperatures greater than 1123 K and the optimum conditions for processing occur at 1273 K and at strain rate of 0.001 s⁻¹. However, at higher temperatures, due to dynamic grain growth, the optimum condition for processing has moved to higher strain rates. Flow instabilities occur in the form of adiabatic shear bands when deformed at strain rates greater than 0.1 s⁻¹ and at temperatures ≤1123 K. A constitutive relationship for hot working is developed to describe the relationship between flow stress, strain rate and temperature.