Abstract
The influence of total finishing strain (from 2.1 to 3.2) and first finishing pass temperature (from 990 to 930°C) was investigated by means of multi-pass torsion tests on three interstitial free (IF) steels containing Ti and/or Nb. All the tests were carried out at a strain rate of 2 s–1. Under strip rolling conditions, static recrystallization is responsible for the high degree of interpass softening in the early passes of rolling. During the final passes, dynamic recrystallization occurs to a degree that depends on the composition of the steel, the total finishing strain and the temperature. The critical temperatures of the IF steels were defined by using a simulated plate rolling schedule. Subjected to the same strip rolling schedule, the niobium stabilized steel had the finest, whereas the titanium stabilized grade had the largest ferrite grain size. The present IF steels exhibit higher no-recrystallization temperatures (Tnr's) during strip rolling 1-2 sec interpass times) than under plate rolling conditions (30 sec interpass times).
