What is it?
This is a crease-like defect that is aligned in a transverse or rolling direction. It might be confined to the edges, but can also appear across the width of the coil. This defect is also known as edge strain, luder lines, or fluting. The name of the defect changes based on its location – if on the coil edge, the defect is called an edge break, and if across the width of the coil – it is called a coil break. The defect is caused by an uneven deformation during processing, which results in the steel being stretched beyond its yield point.