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T

Tack Welds
Small scattered welds made to hold parts of a weld in proper alignment while the final welds are being made.

Tandem Mill
Arrangement of rolling mills, in direct line, allowing the metal to pass from one set of rolls into the next.

Taper Section
A section made at an acute angle to a surface of interest, thereby achieving a geometrical magnification of depth. A sectioning angle 5(degrees) 43 achieves a depth magnification of 10: 1.

Tapping
Transferring molten metal from melting furnace to ladle.

Tarnish
Surface discoloration on a metal, usually from a thin film of oxide or sulfide.

Teeming
Pouring metal into ingot molds.

(2) Pouring molten metal from a ladle into ingot molds. The term applies particularly to the specific operation of pouring either iron or steel into ingot molds.

Telescoping
Transverse slipping of successive layers of a coil so that the edge of the coil is conical rather than flat.

Temper
(1) In heat treatment, re-heating hardened steel or hardened steel or hardened cast iron to some temperature below the eutectoid temperature for the purpose of decreasing the hardness and increasing the toughness. The process also is sometimes applied to normalized steel. (2) In tool steels, temper is sometimes used, but inadvisedly, to denote the carbon content. (3) In nonferrous alloys and in some ferrous alloys (steels that cannot be hardened by heat treatment), the hardness and strength produced by mechanical or thermal treatment, or both, and characterized by a certain structure, mechanical properties, or reduction in area during cold working.

Temper (Met.)
The state of or condition of a metal as to its hardness or toughness produced by either thermal treatment or heat treatment and quench or cold working or a combination of same in order to bring the metal to its specified consistency. Each branch of the metal producing industry has developed its own system of temper designations. In flat-rolled products including sheet and strip steel, tin mill products, stainless strip, aluminum sheet and copper base alloy strip they are shown as follows

Temper Brittleness
A reversible increase in the ductile-brittle transition temperature in steels heated in, or slowly cooled through, the temperature range from about 700 to 1100 F (375 to 575 C).

(2) Brittleness that results when certain steels are held within, or are cooled slowly through, a certain range of temperature below the transformation range. The brittleness is revealed by notched-bar impact tests at or below room temperature.

Temper Rolling
Subjecting metal sheet or strip to a slight amount of cold rolling following annealing (usually 1/2 to 1 1/2%) to forestall stretcher strains. Also termed Pinch Pass or Skin Rolled.

(2) Light cold rolling of sheet steel. The operation is performed to improve flatness, to minimize the formation of stretcher strains, and to obtain a specified hardness or temper.

Tempered and Polished Spring Steel Strip
90/1.03 carbon range (Also known as clock spring steel.) This product, while similar to general description under heading of Tempered Spring Steel Strip, is manufactured and processed with great and extreme care exercised in each step of its production. Manufactured from carbon range of .90/1.03 with Rockwell range C 48/51. Clock spring quality has been ground and polished with edges dressed. It is usually supplied hard blue in color and has a wide range of uses, such as coiled and flat mechanical springs, ignition vibrator springs, springs for timing devices, springs for the electric and electonic fields, steel tapes, rules, etc.

Tempered Spring Steel Strip
Any medium or high carbon (excluding clock spring) strip steel of spring quality which has been hardened and tempered to meet specifications. Where specification calls for blue or straw color, same is accomplished by passing through heat prepared at proper temperature depending on color required. Blue is developed at approximately 600 (degrees) F.

Tempering
Re-heating a quench-hardened or normalized ferrous alloy to a temperature below the transformation range and then cooling at any rate desired.

(2) In heat treatment, re-heating hardened steel to some temperature below the A1 temperature for the purpose of decreasing hardness and/or increasing toughness. The process also is sometimes applied to normalized steel.

Tempering (Also termed 'drawing.')
A process of re-heating quench-hardened or normalized steel to a temperature below the transformation range and then cooling at any rate desired. The primary purpose of tempering is to impart a degree of plasticity or toughness to the steel to alleviate the brittleness of its martensite.

Tensile Strength
In tensile testing, the ratio of the maximum force sustained to the original cross-sectional area.

(2) In tensile testing, the ratio of maximum load to original cross-sectional area. Also called ultimate strength.

Tensile Strength (Also called ultimate strength)
Breaking strength of a material when subjected to a tensile (stretching) force. Usually measured by placing a standard test piece in the jaws of a tensile machine, gradually separating the jaws, and measuring the stretching force necessary to break the test piece. Tensile strength is commonly expressed as pounds (or tons) per square inch of original cross section.

Ternary Alloy
An alloy that contains three principal elements.

Terne Plate
Sheet steel, coated with a lead-tin alloy. The percentage of tin is usually kept as low as possible because of its high cost; however, about 15% is normally necessary in order to obtain proper coating of the steel, since pure lead does not alloy with iron and some surface alloying is necessary for proper adhesion.

Texture
In a polycrystalline aggregate, the state of distribution of crystal orientations. In the usual sense, it is synonymous with preferred orientation, in which the distribution is not random.

Thermal Analysis
A method of studying transformations in metal by measuring the temperatures at which thermal arrests occur.

Thermocouple
A device for measuring temperatures by the use of two dissimilar metals in contact; the junction of these metals gives rise to a measurable electrical potential with changes in temperature.

Thickness Gage or Feeler Stock
A hardened and tempered, edged, ground, and polished thin section, high carbon strip steel. Usually 1/2 in width and in thicknesses from .001 to .050 manufactured to extremely close tolerances. It is used primarily for determining measurement of openings by tool and die makers, machinists, and automobile technicians. It is prepared in handy pocket size knife-like holders containing an assembly of various thicknesses. Also prepared in standard 12 lengths with rounded ends and in 10 ' and 25' coils. Universally used in the metal industry.

Three-Quarter Hard Temper
(A) In stainless steel strip tempers are based on a minimum tensile or yield strength. For Chromium-Nickel grades three-quarter hard temper is 175,000 T.S., 135,000 Y.S. min. (B) In Brass mill terminology, this temper is three B&S numbers hard or 29.4% thickness reduction.

Tin
Chemical symbol Sn. Element No. 50 of the periodic system; atomic weight 118.70. Soft silvery white metal of high malleability and ductility, but low tensile strength; melting point 449 (degrees) F., boiling point 4384 (degrees) F., yielding the longest molten-state range for any common metal; specific gravity 7.28. Principal use as a coating on steel in tin plate; also as a constituent in alloys.

Tin Plate Base Box
A Tin Plate Base Box is measured in terms of pounds per Base Box (112 sheets 14 x 20) a unit peculiar to the tin industry. This corresponds to it's area of sheet totaling to 31.360 square inches of any gage and is applied to tin plate weighing from 55 to 275 pounds per base box. To convert to decimal thickness multiply weight per base box by .00011.

Tin Plating
Electroplating metal objects with tin; the object to be coated is made cathode (negative electrode) in an electrolytic bath containing a decomposable tin salt.

Tinning
Coating with tin, commonly either by immersion into molten tin or by electro-deposition; also by spraying.

Titanium
Chemical symbol Ti. Element No. 22 of the periodic system; atomic weight 47.90; melting point about 3270 (degrees) F.; boiling point over 5430 (degrees) F.; specific gravity 4.5. Bright white metal, very malleable and ductile when exceedingly pure. Its principal functions as an alloy in the making of steel. (1) Fixes carbon in inert particles (a) reduces martensitic hardness and hardnability in medium chromium steels. (b) prevents formation of austenite in high-chromium steels. (c) prevents localized depletion of chromium in stainless steel during long heating. Now finding application in its own right because of its high strength and good corrosion resistance.

Tolerance Limit
The permissible deviation from the desired value.

Tong Hold
The portion of a forging billet, usually on one end, that is gripped by the operator's tongs. It is removed from the part at the end of the forging operation. Common to drop-hammer and press-type forging.

Tool Steel
Any high carbon or alloy steel capable of being suitably tempered for use in the manufacture of tools.

Torsion
A twisting action resulting in shear stresses and strains.

Toughness
Property of resisting fracture or distortion. Usually measured by impact test, high impact values indicating high toughness.

(2) Capacity of a metal to absorb energy and deform plastically before fracturing.

(3) Ability of a metal to absorb energy and deform plastically before fracturing. It is usually measured by the energy absorbed in a notch impact test, but the area under the stress-strain curve in tensile testing is also a measure of toughness.

(4) Extremely small quantity of an element, usually too small to determine quantitatively.

Transformation
A constitutional change in a solid metal, e.g., the change from gamma to alpha iron, or the formation of pearlite from austenite.

Transformation Range
Temperature range over which a chemical or metallurgical change takes place.

Transformation Ranges (transformation temperature ranges)
Those ranges of temperature within which austenite forms during heating and transforms during cooling. The two ranges are distinct, sometimes overlapping but never coinciding. The limiting temperatures of these ranges depend on the composition of the alloy and on the rate of change of temperature, particularly during cooling.

Transformation Temperature
The temperature at which a change in phase occurs. The term is sometimes used to denote the limiting temperature of a transformation range. The following symbols are used for iron and steels: . Ac(cm) In hypereutectoid steel, the temperature at which the solution of cementite in austentite is completed during heating. . Ac1 The temperature at which austenite begins to form during heating. . Ac3 The temperature at which transformation of ferrite to austenite is completed during heating. . Ac4 The temperature at which austenite transforms to delta ferrite during heating. . Ae(cm) Ae1 Ae3 Ae4 The temperatures of phase changes at equilibrium. . Ar(cm) In hypereutectoid steel, the temperature at which precipitation of cementite starts during cooling. . Ar1 The temperature at which transformation of austenite to ferrite or to ferrite plus cementite is completed during cooling. . Ar3 The temperature at which austenite begins to transform to ferrite during cooling. . Ar4 The temperature at which delta ferrite transforms to austentie during cooling. . M(s) (or Ar) The temperature at which transformation of austenite to martensite starts during cooling. . M(f) The temperature at which martensite formation finishes during cooling. . NOTE: All these changes except the formation of martensite occur at lower temperatures during cooling than during heating, and depend on the rate of change of temperature.

Transition Temperature
(1) An arbitrarily defined temperature within the temperature range in which metal fracture characteristics determined usually by notched tests are changing rapidly such as from primarily fibrous (shear) to promarily crystalline (cleavage) fracture. Commonly used definitions are transition temperature for 50% cleavage fracture, 10-ft-lb transition temperature, and transition temperature for half maximum energy. (2) Sometimes also used to denote the arbitrarily defined temperature in a range in which the ductility changes rapidly with temperature.

Transition Temperature (ductile-brittle transition temperature
An arbitrarily defined temperature that lies within the temperature range in which metal fracture characteristics (as usually determined by tests of notched specimens) change rapidly, such as from primarily fibrous (shear) to primarily cleavage.

Transverse
Literally, 'across', usually signifying a direction or plane perpendicular to the direction of working.

Trepanning
A type of boring where an annular cut is made into a solid material with the coincidental formation of a plug or solid cylinder.

Triple Point
The intersection of the boundaries of three adjoining grains, as observed in a section.

Troosite
Tempered martensite that etches rapidly, usually appears dark, and is not resolved by the microscope.

Troosite (obsolete)
A previously unresolvable rapidly etching fine aggregate of carbide and ferrite produced either by tempering martensite at low temperature or by quenching a steel at a rate slower than the critical cooling rate. Preferred terminology for the first product is tempered martensite; for the latter, fine pearlite.

Trowel Steel
Hardened and tempered spring steel. .90 to 1.05 carbon content. Ordinary tolerances, but rolled extra flat -- Rockwell C 50. Used in the manufacture of plastering trowels.

Truss Spring Steel
Supplied cold rolled and bright annealed. Carbon content about .70 -- Manganese .74. Must be formed very severely and must be as free as possible from decarburization.

Tukon Hardness Test
A method for determining microhardness by using a Knoop diamond indenter or Vickers square-base pyramid indenter.

Tumbling
Cleaning articles by rotating them in a cylinder with cleaning materials.

Tungsten
Chemical symbol W. Element No. 74 of the periodic system; atomic weight 183.92. Gray metal of high tensile strength, ductile and malleable when specially handled. It is immune to atmospheric influences and most acids, but not to strong alkalis. The metal is used as filament and in thin sheet form in incandescent bulbs and radio tubes. (1) Forms hard abrasion -- resistant particles in tool steels. (2) Promotes hardness and strength at elevated temperatures.

Tungsten Carbide
Compound of tungsten and carbon, of composition varying between WC and W(2)C; imbedded in a matrix of soft metal, such as cobalt, extensively used for Sintered Carbide Tools.

Twin
Two portions of a crystal having a definite orientation relationship; one may be regarded as the parent, the other as the twin. The orientation of the twin is either a mirror image of the orientation of the parent across a twinning plane or an orientation that can be derived by rotating the twin portion about a twinning axis.

Twin, Annealing
A twin produced as the result of heat treatment.

Twin, Crystal
A portion of a crystal in which the lattice is a mirror image of the lattice of the remainder of the crystal.

Twin, Deformation
A twinned region produced by a shear like distortion of the parent crystal structure during deformation. In ferrite, deformation twins form on {211} planes.

Twist
A winding departure from flatness.