Normal ability to produce steel in a given time period. This
rating should include maintenance requirements, but because
such service is scheduled to match the needs of the machinery
(not those of the calendar), a mill might run at more than
100% of capacity one month and then fall well below rated
capacity as maintenance is performed.
ENGINEERED CAPACITY The theoretical
volume of a mill, given its constraints of raw material supply
and normal working speed.
"TRUE" CAPACITY Volume at full
utilization, allowing for the maintenance of equipment and
reflecting current material constraints. (Bottlenecks of supply
and distribution can change over time--capacity will expand
Steel that has properties made up mostly of the element carbon
and which relies on the carbon content for structure. Most
of the steel produced in the world is carbon steel.
Casing is the structural retainer for the walls of oil and
gas wells, and accounts for 75% (by weight) of OCTG shipments.
Casing is used to prevent contamination of both the surrounding
water table and the well itself. Casing lasts the life of
a well and is not usually removed when a well is closed.
The act of loading material into a vessel. For example, iron
ore, coke and limestone are charged into a Blast Furnace;
a Basic Oxygen Furnace is charged with scrap and hot metal.
An alloying element that is the essential stainless steel
raw material for conferring corrosion resistance. A film that
naturally forms on the surface of stainless steel self-repairs
in the presence of oxygen if the steel is damaged mechanically
or chemically, and thus prevents corrosion from occurring.
WHAT A gas-based process developed
by Lurgi Metallurgie in Germany to produce DRI or HBI (see
Direct Reduced Iron and Hot Briquetted Iron).
HOW The two-stage method yields
fines with a 93% iron content. Iron ore fines pass first through
a circulating fluidized-bed reactor, and subsequently through
a bubbling fluidized-bed reactor.
WHAT Method of applying a stainless
steel coating to carbon steel or lower-alloy steel (i.e.,
steel with alloying element content below 5%).
WHY To increase corrosion resistance
at lower initial cost than exclusive use of stainless steel.
HOW By (1) welding stainless
steel onto carbon steel, (2) pouring melted stainless steel
around a solid carbon steel slab in a mold, or (3) placing
a slab of carbon steel between two plates of stainless steel
and bonding them by rolling at high temperature on a plate
Steel sheet that has been wound. A slab, once rolled in a
hot-strip mill, is more than one-quarter mile long; coils
are the most efficient way to store and transport sheet steel.
WHAT The basic fuel consumed in
blast furnaces in the smelting of iron. Coke is a processed
form of coal. About 1,000 pounds of coke are needed to process
a ton of pig iron, an amount which represents more than 50%
of an integrated steel mill's total energy use.
WHY Metallurgical coal burns
sporadically and reduces into a sticky mass. Processed coke,
however, burns steadily inside and out, and is not crushed
by the weight of the iron ore in the blast furnace.
HOW Inside the narrow confines
of the coke oven, coal is heated without oxygen for 18 hours
to drive off gases and impurities.
Coke Oven Battery
A set of ovens that process coal into coke. Coke ovens are
constructed in batteries of 10--100 ovens that are 20 feet
tall, 40 feet long, and less than two feet wide. Coke batteries,
because of the exhaust fumes emitted when coke is pushed from
the ovens, often are the dirtiest area of a steel mill complex.
WHAT Finishing mills roll cold
coils of pickled hot-rolled sheet to make the steel thinner,
smoother, and stronger, by applying pressure, rather heat.
HOW Stands of rolls in a cold-reduction
mill are set very close together and press a sheet of steel
from one-quarter inch thick into less than an eighth of an
inch, while more than doubling its length.
Cold-Rolled Strip (Sheet)
Sheet steel that has been pickled and run through a cold-reduction
mill. Strip has a final product width of approximately 12
inches, while sheet may be more than 80 inches wide. Cold-rolled
sheet is considerably thinner and stronger than hot-rolled
sheet, so it will sell for a premium (see Sheet Steel).
Cold Working (Rolling)
WHAT Changes in the structure
and shape of steel achieved through rolling, hammering, or
stretching the steel at a low temperature (often room temperature).
WHY To create a permanent increase
in the hardness and strength of the steel.
HOW The application of forces
to the steel causes changes in the composition that enhance
certain properties. In order for these improvements to be
sustained, the temperature must be below a certain range,
because the structural changes are eliminated by higher temperatures.
Measures the physical use of steel by end users. Steel consumption
estimates, unlike steel demand figures, account for changes
APPARENT SUPPLY. Derived demand
for steel using AISI reported steel mill shipments plus Census
Bureau reported imports, less Census Bureau reported exports.
Domestic market share percentages are based on this figure,
which does not take into account any changes in inventory.
WHAT A method of pouring steel
directly from the furnace into a billet, bloom, or slab directly
from its molten form.
WHY Continuous casting avoids
the need for large, expensive mills for rolling ingots into
slabs. Continuous cast slabs also solidify in a few minutes
versus several hours for an ingot. Because of this, the chemical
composition and mechanical properties are more uniform.
HOW Steel from the BOF or electric
furnace is poured into a tundish (a shallow vessel that looks
like a bathtub) atop the continuous caster. As steel carefully
flows from the tundish down into the water-cooled copper mold
of the caster, it solidifies into a ribbon of red-hot steel.
At the bottom of the caster, torches cut the continuously
flowing steel to form slabs or blooms.
Continuous Sheet Galvanizing
A continuous process used to produce a zinc coating on steel
sheet by immersion in a bath of molten zinc. Controlled wiping
of the coating after galvanizing produces thin uniform coatings
of zinc (with no alloy layers), usually 15 to 20 um (0.6 -
0.8 mils) thick. The coating is sufficiently ductile to withstand
deep drawing or bending.
Steel products committed to customers through price agreements
extending 3-12 months. About one-half of all flat-rolled steel
is sold on this basis, primarily because the auto companies
sign agreements to cover at least one year's model. Price
increases that the steel mills might announce during the year
do not generally affect the revenues from the contract side
of the business.
Resources spent to process material in a single stage, from
one type to another. The costs of converting iron ore to hot
metal or pickling hot-rolled coil can be isolated for analysis.
Demand from steel customers such as rerollers and tube makers,
which process steel into a more finished state, such as pipe,
tubing and cold-rolled strip, before selling it to end users.
Such steel generally is not sold on contract, making the converter
segment of the mills' revenues more price sensitive than their
supply contracts to the auto manufacturers.
WHAT COREX is a coal-based smelting
process that yields hot metal or pig iron. The output can
be used by integrated mills or EAF mills.
HOW The process gasifies non-coking
coal in a smelting reactor, which also produces liquid iron.
The gasified coal is fed into a shaft furnace, where it removes
oxygen from iron ore lumps, pellets or sinter; the reduced
iron is then fed to the smelting reactor.
The gradual degradation or alteration of steel caused by atmosphere,
moisture, or other agents.
Heavy gauge, galvanized steel that is spiral-formed or riveted
into corrugated pipe, which is used for highway drainage applications.
Process to uncoil sections of flat-rolled steel and cut them
into a desired length. Product that is cut to length is normally