Internal friction studies on dynamic strain aging in P91 ferritic steel

Abstract

The temperature of dynamic strain aging (DSA) regime in P91 steel is between 523K and 773K. The activation energy (Q) for onset of DSA is 73kJ/mol, while that for finale of DSA is 202kJ/mol. Two main Internal friction (IF) speaks were observed, Snoek and SKK with the activation energy of 67.9kJ/mol and 121kJ/mol, respectively. IF shows that activation energy of 73kJ/mol is equal to that of C atom body diffusion in α-Fe, and 202kJ/mol is equal to binding energy between C atoms and moving dislocations. These results confirm that the mechanism of DSA can be explained by the diffusion of C atoms and pinning between C and moving dislocation. These investigations indicate that DSA in P91 steel is resulted from C atom diffusion, instead of Cr or Mo atoms.