Hot Deformation Behavior of Modified CNS-II F/M Steel

Modified CNS-II F/M steel was designed for in-core components of supercritical water cooled reactor. Study on the hot deformation behavior of modified CNS-II F/M steel is of great importance for processing parameter planning and microstructure controlling during hot deformation. The hot deformation behavior of modified CNS-II F/M steel was investigated through isothermal hot compression test at temperature ranging from 1223 to 1373 K and strain rate 0.01 to 10 s−1. The true stress-true strain data gained from compression tests were used to built constitutive equation of modified CNS-II F/M steel. The influence of strain on the accuracy of constitutive analysis was incorporated, assuming strain has a influence on material constants. A 5th order polynominal equation with very good accuracy was used to represent the influence of strain on material constant. The flow stresses calculated from the constitutive equation were compared with test values in the whole experiment range and the absolute average error for the constitutive equation in predicting flow stress is 4.728%. At last, the recrystallization behavior of modified CNS-II F/M steel was investigated. The relationship of critical strain and peak strain with Zener-Hollomon parameter were given by an experimental equation.