Resisting stress for constitutive analysis of hot deformation in modified 9Cr–1Mo (P91) steel

An Incremental Physically-Based Model of P91 Steel Flow Behaviour for the Numerical Analysis of Hot-Working Processes

“…This procedure is illustrated in Figure 3, giving as a result a confident Q value of approximately 431.7 kJ•mol −1 . The magnitude determined is slightly higher than the previous values reported by Samantaray et al for the P91 steel, who observed a maximum value of 391 kJ•mol −1 [12], whereas in a later study reported an optimum magnitude of about 400 kJ•mol −1 [16]. However, this is in good agreement with the reported values of Krishnan et al [13], which varied between 395 kJ•mol −1 and 465 kJ•mol −1 .…”

“…Finally, it is important to define correctly the DRX kinetics, through the determination of all the parameters involved in Equation (16), relative to the description of the time required for 50% DRX. The kinetics description is accomplished by the evaluation of all the material parameters under different deformation conditions as illustrated in Figure 5.…”

“…Further research on the constitutive formulation of the P91 alloy under hot-working conditions led Samantaray and co-workers [15] to the development of a strain-dependent rate equation for the evaluation of processing conditions on the hot-deformation behaviour of this alloy. More recent work conducted by the same research group [16] involved the analysis of the flow-stress data of the P91 steel on the basis of the Dorn power-law equation and by introducing the concept of resisting stress to dislocation motion. In this analysis, the authors also evaluated the different parameters involved in the rate equation employed for the computation of the stress, at different applied strains.…”