43 Lamination and Delamination

A lamination is a discontinuity or defect that is aligned parallel to the working direction of a metal. Typically, a lamination is the result of ingot steel production. As a steel ingot cools, it may develop a cavity called a pipe. When the ingot is rolled, the pipe becomes elongated and forms a lamination in the steel.

Delamination is the separation of a lamination under stress. The stress could be caused by welding or bending. The applied stress causes the lamination to open up or separate.

The primary difference between the two is that a lamination is a base metal discontinuity that occurs during steel making, whereas delamination occurs when the base metal is worked.