What is it?

This defect looks like a folded-over area that runs diagonally to the rolling direction of the steel. It can also known as pinchers or pinch marks. This defect can happen when material, which is usually very light in gauge (under 0.070 inches), forms loops on the runout table, due to the coiler mandrel not turning fast enough to pull the loops out. The loops are then pulled through the pinch rolls and the crease is created.

Crease