Identification of Hot Working Conditions and No-Recrystallization Temperature for a Cr-Mo-V Reactor Pressure Vessel Steel

Abstract

Abstract Specimens of chromium-molybdenum-vanadium steel, commonly used as reactor pressure vessel material, were hot deformed under uniaxial compression in the temperature range of 700°C–1,200°C and strain rate range of 0.001–10 s−1 in a Gleeble thermomechanical simulator. The strain rate sensitivity (m) map was generated using the flow curves data. The maximum m value of 0.22 was obtained in the temperature range of 1,100°C–1,200°C and strain rate range of 0.01–0.1 s−1. Optical micrographs were used to correlate the deformed microstructures with the hot compression parameters. Kinetics analysis within the high m domain yielded the activation energy as 275 kJ mole−1 and the stress exponent as 4.46. Further, a multistep deformation (at constant strain rate with varying temperature) technique, widely used to identify the temperature of no-recrystallization (inhibition of recrystallization), was performed at 0.001, 0.01, 0.1, and 1 s−1, with temperatures varying from 1,150°C–800°C. The determined value of the temperature of no-recrystallization was approximately 920°C, meaning below this value of temperature dynamic recrystallization would be inhibited.