Constitutive modelling and microstructure evolution of 40Cr alloy steel during hot compression deformation.

Hot deformation behaviour of 40Cr was investigated by conducting hot compression tests at the temperature range of 750–1050°C and the strain rate range of 0·01–10 s⁻¹ on a Gleeble 1500 thermal mechanics simulator. Most true stress–strain curves show that the flow stress increases until a peak value and then decreases with the increasing of the strain, which ends up with a stationary stage. Further microstructural observation confirms the occurrence of dynamic recrystallisation behaviour of 40Cr. The experimental data were used to develop a constitutive equation on the basis of the Arrhenius equation. In the constitutive equation, the effect of strain on deformation behaviour is incorporated, and the flow stress correction parameters p₁, p₂, p₃, p₄ and p₅ are represented by the Zener–Holloman parameter. The flow stresses predicted by the constitutive equation show good agreement with the experimental stresses, with the mean error <4·86%. [ABSTRACT FROM AUTHOR]