Hot deformation behavior and processing map of a 9Cr ferritic/martensitic ODS steel

The hot deformation behavior of 9Cr oxide-dispersion-strengthened (ODS) steel fabricated through the process of mechanical alloying and hot isostatic pressing (HIP) as investigated through hot compression deformation tests on the Gleeble-1500D simulator in the temperature range of 1050-1200 degrees C and strain rate range of 0.001 s(-1)-1 s(-1). The relationship between the rheological stress and the strain rate was also studied. The activation energy and the stress and material parameters of the hyperbolic-sine equation were resolved according to the data obtained. The processing map was also proposed. The results show that the flow stress decreases as the temperature increases, and that decreasing of the strain rate of the 9Cr ODS steel results in a positive strain rate sensitivity. It is clear that dynamic recrystallization is influenced by both temperature and strain rate. The results of this study may provide a good reference for the selection of hot working parameters for 9Cr ODS steel. The optimum processing domains are at 1200 degrees C with a strain rate of 1 s(-1) and in the range of 1080-1100 degrees C with a strain rate between 0.018 s(-1) and 0.05 s(-1). (C) 2014 Elsevier B.V. All rights reserved.