Effect of Static Recrystallization on the Growth of Nb(CN) in A 0.07% Nb HSLA Steel

Constant strain rate hot compression tests were carried out on a 0.07 % C-1.18 % Mn-0.07 % Nb steel at 815 and 930° C. The material was deformed to a strain of 0.25 and then held at temperature for times from 10 to 2.8 × 103s. The interruption strain was chosen to be well below the critical strain for dynamic recrystallization. The size distributions of the Nb(CN) precipitates were determined by the method of extraction replication. The effect of the static recrystallization which occurred during holding on the rate of coarsening of the particles was established. It was found that the fifth power of the mean particle radius, r5, increased linearly with ageing time, t, in keeping with a model for coarsening controlled by the rate of pipe diffusion. It was also observed that r5 increased about three times as fast in the presence of static recrystallization as it does in the absence of recrystallization. The particle number density decreased during recrystallization, apparently as a result of the dis...