The surface defects which exist on the coating substrate can be easily magnified in the galvanized coating process. Identified defects of the strip related to Steel Making Process are :
>Sliver/Shell : Such defects appear in fish-scale shape or blurred stripes
>Hole : An thorough opening on the strip surface >Blow Hole : Tiny hole appearance
>Skin lamination: Such defects may look like scratch defects
>Line Defect: For IF Steel,there are two kind of line defect, Giant line defect causing massive coil rejection and Traditional line defect that damaging only the first coil.
Rolled in scale defect in Hot Strip Mill Product are :Mountain-shaped Scale, Work Roll, Degenaration Scale, Rolled –In Roll Scrap, High Temperature Scale, Red Scale, Insufficient De-scalling Scale.
Appearance defect in galvanized product are Spot Shape Defect : Repeating with fixed distance or Random, Linear Defect, Edge Crack, Edge wave
Source: Cheng Ming Chih , China Steel Corporation, Taiwan