Effect of texture formation on formability of cold rolled and annealed extra deep drawing and inerstitial free steel sheets

Abstract

The extra low and ultra low carbon cold rolled steel sheets are increasingly being used in autobody fabrication to meet the new challenges of weight reduction. The formability of cold rolled and annealed sheet is a critical parameter to decide its performance. The extra deep drawing (EDD) annealed steel is not likely to give consistent forming performance while ultra low carbon interstitial free (IF) cold rolled annealed steel ensures such performance with increased productivity. Formability and texture are interrelated. The aim of texture control is to maximize the tendency for {111} planes in the ferrite grains to lie parallel to the plane of sheet. A sharp {1111 texture in the final annealed product is promoted by fine hot band grain size and high amount of reduction during cold rolling. The effect of texture formation on formability of 80% cold rolled and annealed EDD and IF steel sheets has been discussed in detail. The findings show that the average r bar values of IF steel sheets are much higher than that of EDD steel sheets and the intensity of y-fiber is stronger for IF steel compared to EDD steel both in cold rolled as well as annealed conditions.