Taconite
What Natural mineral containing less than 30% iron. It is the primary ore used in blast furnaces in USA.
Why In USA, domestic supplies of iron-rich ores (greater than 50% iron) were largely depleted in the 1940s, so integrated steel companies now process the lower-grade taconite to make it useful.

Tailored Blanks
A section of sheet or strip that is cut-to-length and trimmed to match specifications for the manufacturer's stamping design for a particular part. Because excess steel is cut away (to save shipping costs), all that remains for the stamper is to impart the three-dimensional shape with a die press (see Blanking).

Tail Scale (Trickle Scale)
Loose scale which flakes off from the ends during hot-rolling or packs of pairs of sheets, and finds its way in between the sheets, and is rolled in during further pack-rolling.

Talbot Process
A modified basic open hearth steel making process adopted for phosphoric iron, and is claimed to give greater output and speed. It consists in tapping only a part of the refined steel, from a large tilting furnace, and then adding a fresh charge to fill up the furnace. The resulting charge gets refined quickly, when a portion is tapped out followed by refilling the furnace.

Tandem Mill
A cluster of rolling mills where mill stands are in tandem. The tandem mill imparts greater strength, a uniform and smoother surface, and reduced thickness to the steel sheet. Unlike the original single-stand mills, a tandem mill rolls steel through a series of rolls (generally three to five in a row) to achieve a desired thickness and surface quality.

Tapping
Taking out refined steel from the furnace into a ladle.

Teeming (Casting, Pouring)
Filling of moulds with finished molten steel from the ladles.

Telescoping Coil
A coil that has not wound properly whose sidewall protrudes out. Tension problems or a bad start on the exit reel causes this condition.

Temper
A condition produced in a metal or alloy by mechanical or thermal treatment and having characteristics structure and mechanical properties. A given alloy may be in the fully softened or annealed temper, or it may be cold worked to the hard temper, or further to spring temper. Intermediate tempers produced by cold working (rolling or drawing) are called "quarter-hard", "half-hard" and "three quarters hard", and are determined by the amount of cold reduction and the resulting tensile properties. In addition to the annealed temper, conditions produced by thermal treatment are the solution heat-treated temper and the heat-treated and artificially aged temper. Other tempers involve a combination of mechanical and thermal treatments and include that temper produced by cold working after heat treating, and that produced by artificial aging of alloys that are as-cast, as-extruded, as-forged and heat treated, and worked.

Temper Code
Industry-standard code that indicates the hardness of the steel.

Tempering
Reheating the quenched steel for a short time to a relatively low temperature to make it less brittle without too drastically lessening the hardness obtained by quenching.

Tempered Layer
A surface or subsurface layer in a steel specimen that has been tempered by heating during some stage of the preparation sequence. When observed in a section after etching, the layer appears darker than the base material.

Temper Mill
A relatively light cold rolling operation in a cold-rolling mill, usually with only one or two stands, that may be used on hot rolled, cold rolled and some coated steel such as galvanized. Temper rolling hot rolled sheet helps to improve flatness, minimize coil breaks and fluting and alter mechanical properties. Temper rolling cold reduced and coated sheet steel improves surface finish (shiny, dull or grooved surface) alters mechanical properties and reduces the tendency of the steel to flute during fabrication.

Temper Rolling
A light cold-rolling process that develops the proper stiffness temper in steel, improves flatness, and imparts a desired surface finish by preventing stretcher strains.

Tensile (Tension) Test
A destructive mechanical test whereby strength and ductility properties are measured.

Tensile Strength
The greatest longitudinal stress steel can sustain without breaking.

Tension Bridle
Or Drag Bridle, is a dynamic tension device used in rolling mills whose function is to produce sufficient drag on the strip to maintain a positive strip tension throughout the line. It consists of a series of rolls, some of which may be pinch rolls, through which the strip passes out of the looper.

Terne Coated Sheet
Sheet steel coated by immersion in a bath of molten terne, an alloy of lead and tin. Terne (meaning dull) principally is used in the manufacture of gasoline tanks, although it also can be found in chemical containers, oil filters and television chassis. Sheet steel coated with terne metal is duller in appearance than sheet steel coated with tin alone.

Thermo-mechanical Treating (TMT)
Permanent deformation of metal with the objective usually of improvement of certain physical properties of the metal.

Thomas Process
A basic steel making process in which pig iron is refined in a basic refractory lined converter by blowing air or a mixture of air, carbon dioxide and oxygen or steam through the molten metal.

Three-Piece Can
Three-piece cans consist of a body and two ends. The body side seam can be accomplished by soldering, cementing or welding. The two ends are attached using a double-rolled seam. The curl on the end, containing the seal compound and its flange on the can body are indexed and rolled flat. The sealing compound between fold gives a hermetic seal.

Tin/Chrome Plating
A plating process whereby the molecules from the positively charged tin or chromium anode attach to the negatively charged sheet steel. The thickness of the coating is readily controlled through regulation of the voltage and speed of the sheet through the plating area.

Tin Coated Steel
See Tin Plate.

Tin-Free Steel
Single or double reduced black plate having a thin coating of chromium and chromium oxide applied electrolytically. Because it is used in food cans just like tin plate, it ironically is classified as a tin mill product. Tin-free steel is easier to recycle because tin will contaminate scrap steel in even small concentrations.

Tin Mill
Continuous tin-plating facility to produce tin mill steel sheet to be used in food and beverage cans and other containers.

Tin Mill Product
Tin Plate, Tin-Free Steel, or Black Plate.

Tin Plate
Thin sheet steel with a very thin coating of metallic tin. Tin plate is used primarily in canmaking.

Tolerances
A customer's specifications can refer to dimensions or to the chemical properties of steel ordered. The tolerance measures the allowable difference in product specifications between what a customer orders and what the steel company delivers. There is no standard tolerance because each customer maintains its own variance objective. Tolerances are given as the specification, plus or minus an error factor; the smaller the range, the higher the cost.

Toll Processing
The act of processing steel for a fee ("toll"). Owners of the steel sheet may not possess the facilities to perform needed operations on the material (or may not have the open capacity). Therefore, another steel mill or service center will slit, roll, coat, anneal, or plate the metal for a fee.

Ton
Unit of measure for steel scrap and iron ore.
Gross Ton 2,240 pounds (1,016.05 kg).
Long (Net) Ton 2,240 pounds (1,016.05 kg).
Short (Net) Ton 2,000 pounds (907.185 kg). Normal unit of statistical raw material input and steel output in the United States.
Metric Ton 1,000 kilograms (2,204.6 pounds or 1.102 short tons).

Tongs
Long-handled pliers used to remove scrap pieces from the welder or other sections of the line.

Tool Steels
Steels that are hardened for the use in the manufacture of tools and dies.

Top Blowing
Injection of oxygen from the top through a water-cooled lance into the liquid bath during oxygen steelmaking. The blowing end of this lance features three to five special nozzles that deliver the gas jets at supersonic velocities. The stirring created by these focused, supersonic jets cause the necessary slag emulsion to form and keeps the vigorous bath flows to sustain the rapid reactions.

Top Dross
Skimmings for the continuous galvanize pot. Composition consists of approximately 87% zinc, 5% aluminum, and 6% to 8% iron.

Torpedo Car (or Ladle)
The refractory-lined hot metal railcar used to carry molten iron from the blast furnace to steel making units.

Toughness
The ability of a metal to absorb energy and deform plastically before fracture.

Tramlines
An overall or lap usually occurring in parallel pairs of lines. Long straight marks due to drawn out inclusions on rolled sheet are also called tramlines.

Transverse
Literally, ‘across’, usually signifying a direction or plane perpendicular to the direction of working. In rolled plate or sheet, the direction across the width is often called long transverse, and the direction through the thickness, short transverse.

Trepanning (Hollow Punching)
Removing a core from a piece of steel either by machining with tubular cutter or by hollow punching that is by pressing a hollow punch through the hot steel.

Tribology
A science that deals with the design, friction, wear and lubrication of interacting surfaces in relative motion.

Triple Spot Test
See Minimum Triple Spot Average Coating.

Trough Castings (Tundish Castings)
Casting or pouring effected through a refractory basin or trough, placed between the ladle and the mould, with the object of minimizing the force of impact of the liquid steel on the bottom plate and thus counteract violent splashings resulting from direct teeming from the ladle into the mould.

Tubing
When referring to OCTG, tubing is a separate pipe used within the casing to conduct the oil or gas to the surface. Depending on conditions and well life, tubing may have to be replaced during the operational life of a well.

Tundish
The shallow refractory-lined basin on top of the copper mould continuous caster. It is an intermediate vessel between the ladle and the mould. It receives the liquid steel from the ladle prior to the cast, allowing the operator to precisely regulate the flow of metal into the mould.

Tundish Nozzle
It is a critical link in the continuous-casting system because it must deliver a constant and controlled flow of steel to the mould with minimum stream flare to minimize splatter, spray, and atmospheric oxidation. Because the ferro-static head remains substantially constant in the tundish throughout casting of much of each heat, the bore of the nozzle must remain at a constant diameter throughout the cast. High purity, stabilized zirconia, having low thermal conductivity and good erosion resistance, has demonstrated the most desirable overall properties of any type of nozzle used to date.

Tunnel Furnace
Type of furnace whereby stock to be heated is placed upon cars which are then pushed or pulled slowly through the furnace.

Turbo-Blower
A steam-turbine-driven centrifugal blower used to provide air blast for blowing the blast furnace.

Tuyeres
The inlets for air to the blast furnace are water-cooled openings called tuyeres and are located at the top of the hearth.

Twist
A bar defect wherein the ends of a bar have been forced to rotate in relatively opposite directions about its longitudinal axis.

Twisting
Torsional displacement of parts of a forging as in the manufacture of a crankshaft.

Type D
Base-metal steel, aluminum killed; sometimes required to minimize severe fluting and stretcher strain hazards for severe drawing applications.