Fluting
1) Visible line markings that sometimes appear on the surface of flat rolled products during forming; associated with non uniform yielding of the metal; occurs when the steel is formed into cylindrical or arc shaped parts. 2) The kinking, or breaking of a sheet generally caused by curing the sheet on two small a diameter. Fluting, or paneling as it is often called, can be avoided by working the steel before bending. Steel with a definite yield point (a visible break in the stress strain curve) will generally tend to flute.