Recrystallization Behavior During Annealing and Its Effect onCorrosion Resistance of Interstitial Free Steel

A interstitial free (IF) steel was annealed at different temperatures (630-780℃) for different time intervals (0-140 min). The microstructure of the annealed steel was observed. The recrystallization behavior was studied, and the recrystallization dynamic model was established. The recrystallization activation energy at different annealing temperatures was obtained. The influence of recrystallization degree on the corrosion resistance was studied. The results show that the higher the annealing temperature, the shorter the time required for the recrystallization, and the larger the recrystallization kinetics parameter n value. The recrystallization activation energy was 221.7 kJ·mol^-1 when annealing at 630-670℃, and was 109.2 kJ·mol^-1 when annealing at 750-780℃. When the volume fraction of recrystallization increased from 18% to 82%, the free-corrosion potential of the test steel in 3.5wt% NaCl solution shifted negatively and the free-corrosion current density increased. When the volume fraction of recrystallization increased to 97%, the free-corrosion potential shifted positively and the free-corrosion current density decreased. With increasing degree of recrystallization, the corrosion resistance of the test steel was first weakened and then strengthened.