microstructural evolution of x45crniw189 valve steel during hot deformation

the hot compression tests were carried on x45crniw189 valve steel (x45) in the temperature rangeof 1000– 1200 °c and the strain rate range of 0.004 – 0.5 s-1 in order to study the high temperaturesoftening behavior of this steel. for the exact prediction of flow stress, the effective stress-effectivestrain curves were obtained from experiments under various conditions. on the basis of experimentalresults, the dynamic recrystallization fraction (drx), austenite grain size (ags), hot deformation andactivation energy behavior were investigated. it was found that the calculated results were in a goodagreement with the experimental flow stress and the microstructure of the steel for different conditionsof hot deformation.