Microstructural Evolution of X۴۵CrNiW۱۸۹ Valve Steel During Hot Deformation

The hot compression tests were carried on X۴۵CrNiW۱۸۹ valve steel (X۴۵) in the temperature range of ۱۰۰۰– ۱۲۰۰ °C and the strain rate range of ۰.۰۰۴ – ۰.۵ s-۱ in order to study the high temperature softening behavior of this steel. For the exact prediction of flow stress, the effective stress-effective strain curves were obtained from experiments under various conditions. On the basis of experimental results, the dynamic recrystallization fraction (DRX), austenite grain size (AGS), hot deformation and activation energy behavior were investigated. It was found that the calculated results were in a good agreement with the experimental flow stress and the microstructure of the steel for different conditions of hot deformation.