Steel sheet with a unique coating of 55% aluminium and 45% zinc that resists corrosion. The coating is applied in a continuous hot-dipped process, which improves the steel's weather resistance. Galbanum® is a trademark of BHP Steel, and the product is popular in the metal building market.

Galvanized Steel
Steel coated with a thin layer of zinc to provide corrosion resistance in underbody auto parts, garbage cans, storage tanks, or fencing wire. Sheet steel normally must be cold-rolled prior to the galvanizing stage.

Steel is run through a molten zinc coating bath, followed by an air stream "wipe" that controls the thickness of the zinc finish.

Electro galvanized
Zinc plating process whereby the molecules on the positively charged zinc anode attach to the negatively charged sheet steel. The thickness of the zinc coating is readily controlled. By increasing the electric charge or slowing the speed of the steel through the plating area, the coating will thicken.

Developing a condition on the rubbing surface of one or both mating parts where excessive friction between high spots results in localized welding with substantial spalling and a further roughening of the surface.

Galvanic Corrosion
Accelerated corrosion of a metal because of an electrical contact with a more noble metal or nonmetallic conductor in a corrosive electrolyte.

Coating steel with zinc and tin (principally zinc) for rust proofing purposes. Formerly for the purpose of galvanizing, cut length steel sheets were passed singly through a bath of the molten metal. Today's galvanizing processing method consists of uncoiling and passing the continuous length of successive coils either through a molten bath of the metal termed Hot Dipped Galvanizing or by continuously zinc coating the uncoiled sheet electrolytically- termed Electro-Galvanizing.

Galvanneal Furnace
A furnace which is placed over the strip as it exits the zinc bath for the purpose of producing a fully alloyed iron-zinc coating. The furnace can be gas fired or induction.

Gamma Iron
The form of iron stable between 1670 (degrees) F., and 2550 (degrees) F., and characterized by a face-centered cubic crystal structure.

Gas economizer
 An auxiliary device designed for temporarily cutting off the supply of gas to the welding equipment except the supply to a pilot jet where fitted

Gas envelope
The gas surrounding the inner cone of an oxy-gas flame.

Gas pore
A cavity generally under 1.6 mm in diameter, formed by entrapped gas during solidification of molten metal.

Gas regulator
A device for attachment to a gas cylinder or pipeline for reducing and regulating the gas pressure to the working pressure required.

The thickness of sheet steel. Better-quality steel has a consistent gauge to prevent weak spots or deformation.

GFM - Gyratory Forging Machine
A machine designed to hot forge a cylindrical bar shape while it is turning at speed.

The property of a surface related to its ability to reflect light. The most common type of gloss of interest to appearance attributes is specular gloss. The parameters which must be specified for the determination of this property are the angles of incidence of the light source, the angle of viewing of the gloss and the angular dispersions of the measuring beams.

A solid polyhedral (or many sided crystal) consisting of groups of atoms bound together in a regular geometric pattern. In mill practice grains are usually studied only as they appear in one plane.
(1) (Direction of) Refers to grain fiber following the direction of rolling and parallel to edges of strip or sheets.
(2) To bend across the grain is to bend at right angles to the direction of rolling.
(3) To bend with the grain is to bend parallel to the direction of rolling. In steel, the ductility in the direction of rolling is almost twice that at right angles to the direction of rolling.
Grain Boundary
Bounding surface between crystals. When alloys yield new phases (as in cooling), grain boundaries are the preferred location for the appearance of the new phase. Certain deterioration, such as season cracking and caustic embrittlement, occur almost exclusively at grain boundaries.
Grain Coarsening
A heat treatment that produces excessively large austenitic grains.

Grain Flow
Fiber like lines appearing on polished and etched sections of forgings, caused by orientation of the constituents of the metal in the direction of working during forging.

Grain Growth
An increase in the average size of the grains in polycrystalline metal or alloy, usually a result of heating at elevated temperature.

Grain Size
Average diameter of grains in the metal under consideration, or alternatively, the number of grains per unit area. Since increase in grain size is paralleled by lower ductility and impact resistance, the question of general grain size is of great significance. The addition of certain metals affects grain size, for example vanadium and aluminum ten to give steel a fine grain. The ASTM has set up a grain size standard for steels, and the McQuaid-Ehn Test has been developed as a method of measurement.

Grain Size number
An arbitrary number calculated from the average number of individual crystals, or grains, that appear on the etched surface of a specimen

Granular Fracture

A type of irregular surface produced when metal fractures, characterized by a rough, grain like appearance as differentiated from a smooth silky, or fibrous, type. It can be sub classified into trans-granular and inter-granular forms.. This type of fracture is frequently called crystalline fracture, but the implication that the metal has crystallized is completely misleading.

The formation of grains immediately upon solidification.

The polymorph of carbon with a hexagonal crystal structure.

Gray Cast Iron
A cast iron that gives a gray fracture due to the presence of flake graphite. Often called gray iron.

Greenfield Steel Mill
New mill that is built "from scratch," presumably on a green field.

Removing material from from a work piece with a grinding wheel or abrasive belt.

Grinding Cracks
Shallow cracks formed in the surface of relatively hard materials because of excessive grinding heat or the high sensitivity of the material.

Ground Flat Stock
Annealed and pre-ground (to close tolerances) tool steel flats in standard sizes ready for tool room use. These are three common grades; water hardening, oil hardening, and air hardening quality.

Device for holding the metal in the proper position, during rolling, or slitting.

Guided bend test
A bend test made by bending the specimen round a specified former. 

Guide Scratch
Scratches or marks appearing parallel to edges of cold rolled strip caused by scale or other particles which have become imbedded in or have adhered to the rolling mill guide. Also applies to similar scratches appearing as a result of slitting.

Gun Drill
A drill, usually with one or more flutes and with coolant passages through the drill body, used for deep hole drilling.