What are the common flatness issues in cold-rolled coils?

2025-09-15 10:04:47

Various sheet form defects may occur during cold-rolled coil production, primarily including: - Waviness (centre wave, edge wave, double-rib wave, etc.), manifesting as periodic undulations on the steel surface; - Sickle bend, referring to lateral curvature along the coil's length; - Buckling, denoting irregular convex-concave deformation within the plane of the steel sheet; Thickness non-uniformity, where thickness variations within a single coil or sheet exceed tolerance limits. These flatness issues primarily stem from uneven pressure distribution during rolling, roller wear, improper tension control, and inconsistent annealing temperatures. Poor plate form compromises subsequent processing precision and reduces product yield rates. Therefore, production must control these issues through measures such as adjusting rolling parameters, replacing rollers, and optimising annealing processes.