One of three directions typically measured in a metal product. The long itudinal direction is parallel with the working of the metal product. It is easily identified in bar and billet products as parallel to the length of the product. More difficult to determine in sheet and plate products, many specifications require stenciling to be administered in the longitudinal direction to eliminate uncertainties. When viewing a product's microstructure, it is the direction parallel with the elongated grain in worked metal products.

The principal direction of flow in a worked metal.