Scale pits/scabs - Cold rolled uncoated sheet

Scale pits/scabs - Cold rolled uncoated sheet - Rolling defects

Figure 1: Scale pits/scabs.

Defect name: Scale pits/scabs
Record No.: 3509
Type of defect (Internal/Surface): Surface
Defect classification: Cold rolling, rolling defects
Steel name: Steel
Steel composition in weight %: No data.
Note:
Definition and appearance: Scale pits / scabs are caused by scale being embedded into the surface of the material during hot rolling. The scale may be removed again by pickling. but the defect may not be completely eradicated during the cold rolling process. The appearance of these flaws ranges from punctiform and linear to wide-area defects.
Occurrence: Scale pits / scabs arise as a result of insufficient pressurised water spraying (descaling) of the hot strip. This leads to scale being rolled in during the hot rolling process.
Identification: Scale pits / scabs are immediately identifiable from their external appearance. Mctallographic examination, particularly of flat microsections, shows that Rolled-in scale only very rarely leads to recognisable structural changes in the surrounding material.
Possibility of mistaken identity: Scale pits / scabs may be confused with hot strip scratches and pickling pits.
Reference: Not shown in this demonstration version.