What are the common surface defects in cold-rolled coils?

2025-09-15 10:19:11

Various surface defects may occur during cold-rolled coil production, primarily including: Scratches, caused by damage from rollers or guide devices; Pitting, resulting from rough surfaces of pickling rolls; oxidation discolouration, surface colour changes arising from inadequate protective atmosphere during annealing; roller marks, periodic imprints on the steel sheet caused by surface defects on the rolling mill rollers; pitting, localised surface depressions potentially caused by foreign object indentation or excessive pickling; edge cracks, fissures appearing along the sheet edges, often related to raw material quality or rolling process; inclusions, defects formed by the exposure of non-metallic inclusions within or on the surface of the steel sheet. These defects compromise product appearance and functional performance, necessitating control through process optimisation and enhanced inspection during production.