Expansion scab - Casting defects

Expansion scab - Casting defects

Figure 1: Expansion scab.

Defect name: Expansion scab
Record No.: 46
Type of defect (Internal/Surface): Surface
Defect classification: Casting defects
Steel name: Cast iron
Steel composition in weight %: No data.
Note: Your iron casting shows local accumulations of coarse graphite. The graphite has moved into the shrinkage cavities.
Expansion Scab—Another defect caused by the expansion of molding or core sand, expansion scabs can occur in ferrous or copper-based castings. The thin metallic projections with sharp edges are generally parallel to the surface of the casting and have very rough surfaces. They are usually attached to the casting at only a few points.
Reference: Not shown in this demonstration version.