Study of Deformation Behavior of Simulated Inter-Critical Heat-Affected Zones of Modified 9Cr-1Mo Steel

Deformation behavior of Gleeble-simulated inter-critical heat affected zone (ICHAZ) of modified 9Cr-1Mo steel has been studied using instrumented microhardness testing. The strain rate sensitivity exponent and activation volume of ICHAZs produced from steels with different prior austenite grain sizes (PAGS) have been estimated. In the simulated ICHAZ, the strain rate sensitivity exponent is lower for larger PAGS (100-120 mu m) than for smaller PAGS (20-30 mu m), while the activation volume is higher for larger PAGS. The slope of the loading line at any given point was higher in the simulated ICHAZ of the steel with larger PAGS, indicating that the ICHAZ in the steel with larger PAGS is more resistant to deformation than in the steel with smaller PAGS.