Lacquer

Occasionally used to describe oil stain.

Lamellar Tear

A system of cracks or discontinuities aligned generally parallel to the worked surface of a plate. Usually associated with a fusion weld in thick plate.

Laminant

The bonding agent used in joining two or more sheet or films.

Lamination

An abnormal structure resulting in a separation or weakness aligned generally parallel to the worked surface of the metal.

Lap

A surface defect, appearing as a seam, caused by fording over hot metal, fins, or sharp corners and then rolling or forging them into the surface, but not welding them.

Lap-Weld

A term applied to a weld formed by lapping two pieces of metal and then pressing or hammering, and applied particularly to the longitudinal joint produced by a welding process for tubes or pipe, in which the edges of the skelp are beveled or scarfed so that when they are overlapped they can be welded together.

Lateral Bow

Deviation of a longitudinal edge from straight (sometimes called camber).

Lattice

Space lattice. Lattice lines and lattice planes are lines and planes chosen so as to pass through collinear lattice points, and non-collinear lattice points, respectively.

Leveling

Flattening rolled metal sheet or strip.

Leveling, Roller

Leveling carried out by bending.

Leveling, Stretcher

Leveling carried out by uniaxial tension.

Leveling, Tension

Leveling continuously carried out by uniaxial stretching usually with the assistance of bending.

Leveling, Thermal

Leveling carried out at an elevated temperature under an applied load normal to the surface to be flattened.

Leveller, Chatter

Numerous intermittent lines or grooves that are usually full width and perpendicular to the rolling or extrusion direction.

Leveller, Streak

A streak on the sheet surface in the rolling direction caused by transfer from the leveler rolls.

Light Metals

Metal and alloys that have a low specific gravity, such as beryllium, magnesium and aluminum.

Line, Flow

The line pattern which shows the direction of flow on the surface.

Line, Looper

Closely spaced symmetrical lines on the surface of metal which has undergone non-uniform deformation, usually in a drawing operation.

Line, Luders

Elongated surface markings or depressions appearing in patterns caused by localized plastic deformation that results from non-uniform yielding.

Liner

The slab of coating metal that is placed on the core alloy and is subsequently rolled down to clad sheet as composite.

Liquated Edge

Surface condition remaining after portions of a side of an as-cast rolling ingot deforms enough during hot rolling to become top and/or bottom surface(s) of the rolled product at an edge.

Liquation

Partial melting of an alloy.

Liquidus

In a constitutional diagram, the locus of points representing the temperatures at which various components commence freezing on cooling or finish melting on heating.

Lithographic Sheet Aluminum

Sheet having a superior surface on one side with respect to freedom from surface imperfections and supplied with a maximum degree of flatness, for use as a plate in offset printing.

Long Transverse Direction

For plate, sheet and forgings, the direction perpendicular to the longitudinal direction which is also at right angles to the thickness of the product.

Longitudinal Bow

A longitudinal curvature in the plane of a sheet.

Longitudinal Direction

The principal direction of flow in a worked metal.

Loose Wrap

A condition in a coil due to insufficient tension which creates a small void between adjacent wraps.

Lot, Heat Treat

Material of the same mill form, alloy, temper, section and size traceable to one heat-treat furnace load (or extrusion charge or billet in the case of press heat-treated extrusions) or, if heat treated in a continuous furnace, charged consecutively during an 8-hour period.

Lot, Inspection

Lube, High

Lubricant limit exceeds the maximum agreed upon limit measured in weight per unit area.

Lube, Low

Failure of the lubricant to meet the agreed upon minimum limit measured in weight per unit area.

Lubricant Residue

The carbonaceous residue resulting from lubricant burned on the surface of a forged part.

Luders Lines

Surface markings resulting from localized flow which appear on some alloys after light straining. They lie approximately parallel to the direction of the applied maximum shear stress (about 45 degrees to the direction of the applied stress), and appear as depressions when forming is in tension and as elevations when in compression.