Hair Line Cracks (Hair Cracks)
Internal ruptures in steel caused by stresses which arise from the
combination of several factors, such as volume changes due to
transformation, brittleness due to the presence of hydrogen, and the
arrangement of the micro-structure, resulting from hot working. The size of
such ruptures may vary considerably but they are usually comparatively
short in length when viewed on a surface cut at right angles to the plane
of defect and generally are so fine that they cannot be discerned other
than after etching or by magnetic crack detection.
Half-Hard Temper
Cold Rolled steel produced to a Rockwell hardness range of 70 to 85 on the
B scale. Product of this temper is intended for limited cold forming and
will only withstand 90-degree bends made across the rolling direction.
Hangar Crack
A transverse ingot crack caused by obstruction to normal contraction of an
ingot during cooling in mould, and is associated with incorrect feeder head
setting. Also occurs from overfilling.
See Slips.
The relative ability of a ferrous alloy to form martensite when quenched
from a temperature above the upper critical temperature. Hardenability is
commonly measured as a distance below a quenched surface at which the metal
exhibits a specific hardness– 50 HRC, for example- or a specific
percentage of martensite in the micro-structure.
Increasing hardness by suitable treatment, usually involving heating and
cooling. See also age hardening, case hardening, induction hardening,
precipitation hardening, and quench hardening.
A measure of the resistance of a material to surface indentation or
abrasion; may be thought of as a function of the stress required to produce
some specified type of surface deformation. There is no absolute scale for
hardness; therefore, to express hardness quantitatively, each type of test
has its own scale of arbitrarily defined hardness. Indentation hardness can
be measured as Brinell, Rockwell, Vickers, Knoop, and Scleroscope hardness
Hardness Value
Degree to which a material resists deformation, indentation or scratching.
There are many numerical scales (and thus methods) to measure the hardness
value (example: Brinell, Rockwell, Vickers, etc.)
Heat (of Steel)
A batch of refined steel. A basic oxygen or electric furnace full of steel.
One heat of steel will be used to cast several slabs, blooms or billets.
Heat Affected Zone
That portion of the base metal that was not melted during brazing, cutting,
or welding, but whose microstructure and mechanical properties were altered
by the heat.
Heat Cover
A cylindrical or rectangular inner cover placed over the coils prior to
placing the furnace on the base in the Batch Anneal.
Heat Exchanger
Removes heat from oil with water.
Heat Exchanger Tubes
Tubes used in a unit for the purpose of transferring heat from one medium
to another.
Heat Number
In the Batch Anneal, this is the computerized annealing sequence number
used by the Firing Model to associate target values to the Heat Sequence.
It is required to run the Firing Model. In the BOP a sequential number
assigned to each batch of steel.
Heat Tinting
Coloration of a metal surface through thermal oxidation by heating to
reveal details of structure.
Heat Treatment
What Altering the properties of steel by subjecting it to a series of
temperature changes. 
Why To achieve the desired microstructural / mechanical properties like the
hardness, strength, or ductility of steel or alloys so that it is suitable
for additional applications. 
How The steel is heated and then cooled as necessary to provide changes in
the structural form that will impart the desired characteristics. The time
spent at each temperature and the rates of cooling have significant impact
on the effect of the treatment.
Heat Waste (Fire Waste)
The loss of material by scaling in a reheating or hot working process.
Heavy Coating
A condition caused by too much coating being applied to the strip.
Heavy Gauge 
Product with a thickness above the customer's maximum gauge tolerance.
Heavy/Light Gauge
Steel plate not meeting customer gauge specifications.
Heavy Structural Shapes
A general term given to rolled flanged sections that have at least one
dimension of their cross sections three inches or greater. The category
includes beams, channels, tees and zees if the depth dimension is three
inches or greater, and angles if the length of the leg is three inches or
Term used to describe the frequency in an AC circuit. Essentially the same
as cycles. If a circuit is 60 Hz or 60 cycles, that means that the AC wave
has gone through 60 complete waves in one second.
A coating defect consisting of a randomly oriented small speckled
appearance on coated plate after inks are applied.
High Hot-Blast Temperatures
Use of better stove-firing techniques, better stove-changing equipment,
improvements in burden materials, the use of tuyere-injected fuels and the
control of blast moisture make it possible for the blast furnace to accept
the higher hot-blast temperatures (upto 1250o C). This results in reduction
in coke rate as well as improvement in blast furnace efficiency.
High Rockwell
A condition that occurs when the hardness of the steel is above the maximum
limit as specified by the customer.
High Speed Steel
A special variety of tool steel which, by virtue of its composition,
retains its cutting hardness at a low red heat.
High Strength Low Alloy (HSLA)
A specific group of steel in which higher strength, and in some cases
additional resistance to atmospheric corrosion or improved formability, are
obtained by moderate amounts of one or more alloying elements such as
columbium, vanadium, titanium, used alone or in combination.
A mixture of hydrogen and nitrogen gas used to prevent oxidation and to
clean the strip during the annealing process.
Coil type indicating that a produced coil or lift has problems that need to
be resolved by the Quality Assurance department.
Hollow Forging
Forging a tube, ring or drum on a becking bar or mandrel.
Home Scrap
Also called 'revert scrap', it includes such items as pit scrap ; ingots
too short to roll; rejected ingots; crop ends from slabs, blooms and
billets; shear cuttings from trimming flat-rolled products to specified
size; products irrevocably damaged in handling or finishing; ends cut from
structural shapes, rails, bars, pipe or tubing to bring them to standard or
exact ordered lengths; turnings from machining operations, broken moulds;
obsolete machinery, dismantled buildings, steel shot recovered from slag,
and so on. Bloom and slab crops constitute the largest single item of home
Holding at high temperature to eliminate or decrease chemical segregation
by diffusion.
A short bend or curvature caused either by improperly adjusted delivery
guides or by any obstruction which may halt momentarily the forward motion
of the bar from one roll stand to another.
Horse Shoe Quality
A quality of wrought iron specifically manufactured for horse shoes.
Hot Band (Hot-Rolled Steel)
A coil of steel rolled on a hot-strip mill (hot-rolled steel). It can be
sold in this form to customers or further processed into other finished
Hot-Dip Galvanizing After Fabrication
A batch process used to produce a zinc coating on manufactured steel
products by total immersion of structural or fabricated steel in a bath of
molten zinc. The process provides a metallurgically bonded coating,
generally 100 um (4 mils) thick, consisting of iron-zinc alloy layers
covered with zinc.
Hot Drawn
Tubes which have been reduced in diameter, or diameter and thickness both,
by drawing hot on a mandrel through a die.
Hot End
The section of a steel making complex from the furnace up to, but not
including, the hot-strip mill.
Hot Etching
Development and stabilization of the micro-structure at elevated
temperature in etchants or gases.
Hot Forming
Operations such as bending and pressing, after heating the material to
appropriate temperature.
Hot Metal
The name for the molten iron produced in a blast furnace. It proceeds to
the basic oxygen furnace in molten form or is cast as pig iron.
Hot Metal Process
A steel making process using molten metal from blast furnace mixer or
cupola as major portion of the charge.
Hot Mill
The rolling mill that reduces a hot slab into a coil of specified
thickness; the whole processing is done at a relatively high temperature
(when the steel is still 'red').
Hot Quenching
An imprecise term for serious quenching procedures in which a quenching
medium is maintained at a prescribed temperature above 70o C.
Hot Roll
Product that is sold in its "as produced state" off the Hot Mill with no
further reduction or processing steps aside from being pickled and oiled
(if specified).
Hot Roll Base
Hot rolled coils which have been pickled in an acid solution to remove
surface oxidation, then is oiled to prevent rust. Coils that come directly
off the Pickling Line and are not cold roll reduced on the tandem mill.
Hot Roll, P and O
Hot Roll Pickle and Oil that does not go to a in-house Tandem Mill. It may
not necessarily be shipped out; it could go to the Temper Mill.
Hot Rolled Sheets
Manufactured by hot rolling slabs to the required thickness.
Hot Sawing
Cutting hot iron to length during or immediately following hot rolling, by
a circular saw.
Hot-Strip Mill
A rolling mill of several stands of rolls that converts slabs into
hot-rolled coils. The hot-strip mill squeezes slabs, which can range in
thickness from 2-10 inches, depending on the type of continuous caster,
between horizontal rolls with a progressively smaller space between them
(while vertical rolls govern the width) to produce a coil of flat-rolled
steel about a quarter-inch in thickness and a quarter mile in length.
Hot Working
Plastic deformation of metal at temperatures higher than recrystallization
temperature. The forces required to deform the metal are very insensitive
to the rate of application of loads and to temperature variations, but the
basic strength of the metal after the deformation is essentially unchanged.
A forming process in which a tube is placed into a forming die. The tube is
then formed to the shape of the die through the application of internal
water pressure. The hydroforming process allows for severe shape
deformation, making it ideal for automotive structural parts such as engine
cradles, radiator supports and body rails. Various shaped and sized holes
can be punched in the tube almost anywhere during the process.
Hydrogen Damage
A general term for the embrittlement, cracking, blistering, and hydride
formation that can occur when hydrogen is present in some metals.
Haematite (Hematite)
Iron oxide, having a composition Fe2O3, corresponding to 69.94% of iron and
30.06% of oxygen, specific gravity 5.26, occurring in nature in igneous,
metamorphic, and sedimentary rocks as a product of the weathering of
magnetite and associated with varying amounts of impurities.
Hard Drawn Wire
Wire drawn with a relatively large reduction(over 10%) from the rod without
heat treatment.
Hardness Index
A property of metallurgical coke to withstand abrasion. It is expressed as
the percentage of coke remaining on ¼-inch screen when the coke of
selected size is screened after it has been tumbled in a standard drum
which is rotated for a specific time at a specific rate.
High Carbon Steel
Carbon steel containing generally more than 0.6% carbon. The more carbon
that is dissolved in the iron, the less formable and the tougher the steel
becomes. High-carbon steel's hardness makes it suitable for plow blades,
shovels, bedsprings, cutting edges, or other high-wear applications.
The membrane-type construction (alongwith the stacks) above the basic
oxygen furnaces leading to the gas cleaning and dust collecting facilities
are called hoods. These are cooled by water flowing in 1 ½ inch dia steel
tubes separated on 2 inch centres.
Hot Briquetted Iron (HBI)
Direct reduced iron that has been processed into briquettes. Instead of
using a blast furnace, the oxygen is removed from the ore using natural gas
and results in a substance that is 90%-92% iron. Because DRI may
spontaneously combust during transportation, HBI is preferred when the
metallic material must be stored or moved.
Hydraulic Lap-weld Process (Water-Gas Lapweld Process)
A process for making large diameter welded tubes in which a steel plate is
bent into cylindrical shape in bending rolls. The overlapping edges are
heated for short distances to welding temperature and subsequently welded
by pressing them together by hydraulic power. The heating and pressing is
repeated until the length is welded. The tube is then heated all over and
passed through rounding rolls. For certain sizes, two plates may be
required to make the necessary circumference.
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