Relation between formability and precipitates in Ti-IF enamelling steels

The influence of steel composition and processing conditions on the nature of precipitates in Ti interstitial free (IF) steels for enamelling were investigated in detail. Steels designed for enamelling applications require a higher amount of precipitates than conventional deep drawing IF steels, e.g. for automotive applications. Formable IF grades for enamelling applications have high Ti, S and C contents and the properties have hitherto not been investigated in detail. This work focused on the correlation between precipitate nature, texture development and deep drawability. It was found that a low reheating temperature, a high coiling temperature and a C/S ratio in the range of 0.4–0.5, favoured the beneficial precipitation of Ti₄C₂S₂. Furthermore, it is shown that for a steel with a given C/S ratio, a high Ti₄C₂S₂/Ti₄S₅-ratio resulted in improved deep drawability. The deep drawability decreases with increasing C/S ratio. This is due to the decrease in γ-fibre intensity, caused by an increased amount of TiC-precipitates.