There are number of defects occur during rolling process but all these defects are mainly classified into two types which are following
- Surface defects
- Structural defects
Those defects which can be seen physically by naked eye are known as surface defects. Surface defects occur due to number of reasons like scaling, rusting, dirt, marks of roll etc.
Structural defects are those defects which occur at microscopic level of the work piece. Main drawback of this defect is on the life of the roll product.
The structural defects are following
- Wavy edges
- Zipper cracks and edge cracks
Wavy edges occur when our roll bend. Due to this reason, the edges of the roll product become thinner as compare to center part of the product. The crack appear in the center of the product is known as zipper cracks and the crack appear due to low ductility and barreling of the product is known as edge cracks. The last type of structural defect is alligatoring which occurs due to inhomogeneous deformation of the roll product during rolling process.