Monitoring Recovery and Recrystallization in Interstitial Free (IF) Steel by Magnetic Hysteresis Loop Measurements

In this paper, how structure-sensitive parameters derived from the hysteresis loop, like coercive field, remanent induction, and hysteresis losses, can be used to characterise recovery and recrystallization in cold rolled Ti-Nb stabilised interstitial free ultra low carbon steel is shown. The effect on hysteresis measurements of isothermal annealing treatments applied to industrially cold rolled samples at different temperatures is related to the microstructural changes which take place during the annealing as a consequence of the metallurgical recovery and recrystallization processes. It has been observed that the remanent magnetic field, the coercive field and the hysteresis losses can be used to monitor recovery. Furthermore, recrystallization can be characterised by coercive field and hysteresis loss measurements. Additionally, the effect on magnetic parameters of hardness indentations made after the annealing is studied. It has been shown that remanent magnetic field measurements are affected by hardness indentations present in the samples, while coercive field and hysteresis losses do not change.