Deciphering the genesis of ridge defects in steel strips: a multifaceted approach

The ridge buckle defect is a perennial challenge in the Steel Industries. Its sporadic appearance at the cold rolling mill (CRM) precipitates the degradation of cold-rolled products. It is unequivocally established that the genesis of this defect lies within the hot strip mill (HSM), manifesting during the cold rolling process subsequent to annealing and skin-pass rolling. In spite of several research attempts, conclusive evidence to definitively resolve this issue remains elusive. This study endeavours to analyse the effect of ramifications of thickness variation in the transfer bar (TB) from the roughing mill, directly fed into the finishing stands of the HSM, on roll wear and strip profile. We hypothesize that this variation may predispose the TB to ridge buckle defects. To investigate this, the study conducts a meticulous statistical and experimental inquiry into the impact of thickness variation in the TB from the roughing mill on the wear of work rolls, which could be a catalyst for ridge buckle defects. The analysis unequivocally corroborates that the incidence of ridge defects is intricately intertwined with the wear profile of the work rolls of last roughing stand (i.e., R5), aligning with the prevailing production conditions within actual plant operations.