Asymmetric Rolling of Interstitial-Free Steel Using One Idle Roll

The effect of additional shear on the asymmetric rolling (ASR) of an interstitial-free (IF) steel was studied by modeling and experiments. The asymmetry was introduced by making one roll idle. A 66 pct of total thickness reduction was performed in 6 passes with less than 16 pct reduction per pass. ASR was performed in two ways: monotonically and by rotating the sheet between passes by 180 deg around the rolling direction (RD). Better grain fragmentation was obtained in the near surface layers. The results of monotonic asymmetric rolling are similar to symmetric rolling in terms of misorientation and cell size with the difference that the volume fraction of grains containing shear bands (SB) is larger for monotonic ASR. ASR with the sheet rotated 180 deg around the RD direction between passes showed the most promising results in terms of grain refinement, depth of the highly deformed layer, texture, and properties. The grain fragmentation process was also simulated with a recent grain refinement polycrystal model for strain hardening, texture development, grain size distribution, and grain misorientation distribution. The obtained simulation results showed strong agreement with the experiments.