Effect of water quenching process on the microstructure and magnetic property of cold rolled dual phase steel

The effects of water quenching process on the microstructure and magnetic property of cold rolled dual phase steel are investigated. Correlations of microstructure, magnetic properties and water quenching parameters are established. The results show that the microstructure of the dual phase steels mainly consists of the ferrite and martensite phase, the martensite volume fraction increases gradually on increasing the holding and quenching temperature. It is found that magnetic properties of dual phase steel are very sensitive to the quenching process. Based on the minor hysteresis loop results, the coercivity and hysteresis loss increase obviously with the increase of quenching temperature, while the remanent induction and the maximum permeability tend to decrease. Furthermore, the magnetic domain structure of the ferrite phase in the presented dual phase steel is observed by magnetic force microscopy. The mechanism of the magnetic property varying with the quenching process is also discussed.