Formability of ultrafine-grained interstitial-free steel fabricated by accumulative roll-bonding and subsequent annealing

The miniaturized Erichsen test was successfully developed for evaluating the stretch formability of the ARB and annealed IF steel sheets. The Erichsen value tends to decrease as the average grain size becomes small. However, it should be emphasized that even in the specimen with ultrafine grain, a high Erichsen value is obtained. This result indicates that the ultrafine grained IF steel sheet could be highly deformed under multiaxial stress.