शब्दावली


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Galling
A condition whereby excessive friction between high spots results in
localized welding with subsequent spalling and a further roughening of the
rubbing surfaces of one or both of two mating parts.
Galvanneal Coatings (A Coatings)
Coatings on hot-dipped galvanized steels processed to convert the coating
completely to zinc-iron alloys; dull gray in appearance, have no spangle,
and after proper preparation, are well suited for painting without
additional surface preparation, can withstand moderate forming and are more
weldable than galvanized coatings.
Galvanize
A sheet product substrate to which free zinc is applied either by
hot-dipping or electro-plating.
Galvanize Coatings (G Coatings)
Free zinc coatings applied to a hot rolled or cold rolled steel to produce
galvanized steel. The coating can be applied by the hot-dip or
electro-deposition process.
Galvanneal Furnace
A furnace (gas-fired or induction) which is placed over the strips as it
exits the zinc bath for the purpose of producing fully alloyed iron zinc
coating.
Galvanizing
Coating steel with a thin layer of zinc to increase its corrosion
resistance. Most galvanizing is done on a hot-dip operation, but
electro-galvalizing is becoming more important today. Electro-galvanizing
is a cold-coating electroplating process that, unlike the hot-dip process,
does not influence the mechanical properties of the sheet steel.
Electro-galvanizing provides a more uniform coating.
Galvanizing Pot
Holds the molten free zinc coatings applied to a hot rolled or cold rolled
steel to produce Hot-dip Galvanized steel.
Galvannealed
An extra tight coat of galvanizing metal (zinc) applied to a soft steel
sheet, after which the sheet is passed through an oven at about 1200
degrees F. The resulting coat is dull gray without spangle especially
suited for subsequent painting.
Gangue
art of an ore, which has to be either removed during benefication of the
ore, or slagged during smelting.
Ganister
A siliceous refractory material used in acid furnace.
Gardner Impact Test
In this test, a projectile is dropped from a particular distance to dent
the steel to various depths. The impact is measured in inch-pounds, and the
coating adherence is determined by assessing flaking or crazing on the
convex side of the cup.
Gas Carburising
Carburising carried-out by heating the steel in direct contact with
carburizing gases.
Gas Knife
It consists of a stream of gas, usually air or stream, directed at both
sides of the strip being galvanized, as it emerges from the coating bath.
The pressure of the gas and the positioning of the knife relative to the
strip surface are controlled to give the desired weight of coating for the
speed used. In special cases, nitrogen gas is used to produce a smoother
finish.
Gate
The clearance cut in the front of a die to accommodate the bar undergoing
forging and to retain a connection between the bar & the forging.
Gathering
Increasing the cross section of the stock beyond the original size.
Gauge
1. An instrument that measures pressure, temperature, level or flow
depending on the purpose.
2. The thickness of the steel strip. Better-quality steel has a consistent
gauge to prevent weak spots or deformation.
Gauge Code
Industry-standard code that indicates quality tolerance of the thickness of
the steel.
Gauge Tolerance
A range by which a product's gauge can deviate from those ordered and still
meet the order's requirements.
Gel Spotting
A coating defect consisting of the uniform circular spots or droplets of
higher film thickness on the coated sheet. Gel spotting, while appearing
similar to slinging, is much more uniform in appearance and caused by a
different mechanism. Gel spotting occurs when a partially gelled coating is
applied to the substrate.
Geometric Marking
Unusual design put on one side (lite coating) of a coil to identify a
different coating weight.
Ghost
A segregated streak, usually containing a concentration of sulphide, oxide,
etc. which have become elongated during rolling or forging. This looks
different in colour than the rest of the sheet when sheet is tarnished.
Goethic Section 
A rolled or forged product having approximately square section. The
dimensions are specific with specified radius or chamfer at corners without
any concavity on the sides.
Gouges
A gross type of scratch.
Grade
The term grade designates divisions within different types based on carbon
content or mechanical properties; for example, 'This is a high tensile
(grade) structural steel'.
Grain Structure 
Microstructure consisting of grains (crystals) and phases in metals;
generally requires examination under a microscope of an etched, polished
specimen for observation.
Granular Fracture
A type of irregular surface produced when metal is broken that is
characterized by a rough, grain-like appearance, rather than a smooth or
fibrous one. It can be sub-classified into trans-granular and
inter-granular forms. The fracture is frequently called crystalline
fracture, but the implication that the metal failed because it crystallized
is misleading, because all metals are crystalline in the solid state.
Granulated Slag
Molten blast-furnace slag is quenched quickly in water to form a product
called ‘granulated slag’. No crystallization occurs in this
process. Depending upon chemical composition of the slag, its temperature
at the time of quenching in water, and the method of production utilized,
the physical structure of the granulated grains may vary from a friable
popcorn-like structure to grains resembling dense glass.
Graphite Electrodes
Made from petroleum coke at high heat to form artificial crystalline
carbon, graphite electrodes are used in electric steel-making furnaces.
Graphitization
The decomposition of iron oxide or, in any event, the rejection of
elemental carbon in a casting after solidification has taken place, the
carbon being liberated in the form of graphite which is usually found
existing as minute, flaky particles disseminated throughout the casting.
Graphitizing
Annealing a ferrous alloy such that some or all the carbon precipitates as
graphite.
Greenfield Steel Mill
New mill that is built 'from scratch,' presumably on a green field.
Grinding
Removing material from a workpiece using a grinding wheel or abrasive belt.
Grit Size
Nominal size of abrasive particles in a grinding wheel, corresponding to
the number of openings per linear inch in a screen through which the
particles can pass.
Grit
1. Texture of the surface of a roll; applied through sand-blasting and
grinding; the lower the number, the higher the grit and the rougher the
surface; 50, 90, 150, 200, and 220 grit. Temper Mills may run grit. Grit
also refers to the finish on the surface of the steel.
2. The size of the shot blast used to mechanically texture a roll for
producing a grit finish product. Grit can be classified as either night or
heavy. Light grit is a non-metallic inorganic material with excellent
abrasive characteristics, such as aluminum oxide. Heavy grit is principally
of the metallic type such as cast-iron shot. Metallic grit is the type most
generally used on a bar product.
Grit Blasting
Or blast-cleaning, is a mechanical process used for removing scale and rust
from bar products. It consists of eroding or abrading away the scale from
the surface of the bar impinging an abrasive substance like sand, aluminum
oxide, or a metallic substance like cast iron or steel shot.
Ground Roll Finish
The bright or smooth microfinish on the last stand of a tandem mill or
temper mill; produced by grinding; determines the surface finish of the
product where brightness is desired.
Guides
In order to prevent collaring and to ensure that the steel piece being
rolled enters and leaves the pass in the correct position, guides are
employed. These guides vary in form and size to fit the conditions. Guides
may be employed on both sides of the pass, in which case they are
designated as entering guides and delivery guides.
Guards
Devices employed mainly on the delivery side of the mill to control the
direction of the piece being rolled after it leaves the pass. Reversing and
three-high mills are provided with guards on both sides of the mill.
Gutter
A recess surrounding the impression in the die face , to receive access
metal beyond the fash proper.
Galvalume®
Steel sheet with a unique coating of 55% aluminum and 45% zinc that resists
corrosion. The coating is applied in a continuous hot-dipped process, which
improves the steel's weather resistance. Galvalume® 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. 
Hot-dipped. 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. 
Differences. Electro-galvanizing equipment is more expensive to build and
to operate than hot dipped, but it gives the steel maker more precise
control over the weight of the zinc coating. The automotive manufacturers,
because they need the superior welding, forming and painting ability of
electro-galvanized steel, purchase 90% of all tonnage produced.
Guide Mark (Guide Scratch, Guide Score, Guide Shearing)
A surface defect resulting from abrasion between the steel / iron and a
guide used for ensuring location in rolling.
Go to Top
Copyright © 2012 SAIL, all rights reserved
Designed & Developed by Cyfuture