Influence of TiN Particle Precipitation State on Static Recrystallisation in Structural Steels

This paper studies the influence of different Ti and N contents, which give rise to different precipitation states at the reheating temperatures, on the static recrystallisation of austenite in structural steels. The influence of the precipitation state has been quantified by the changes in the activation energy value (Qx), which measures the greater or lesser facility for grain boundary self-diffusion, the mechanism that is responsible for recrystallisation. A maximum has been obtained for the activation energy which corresponds to the finest precipitate distribution and a Ti/N ratio close to unity, although the excess Ti content in solution also contributes to a considerable increase in Qx. The values obtained for the driving forces of recrystallisation have always been greater than the pinning forces, allowing static recrystallisation to take place irrespective of the chemical composition of the steel and the strain applied.