BAINITE
A slender, needle-like (acicular) microstructure appearing in spring steel strip characterized by toughness and greater ductility1 than tempered Martensite. Bainite is a decomposition2 product of Austenite best developed at interrupted holding temperatures below those forming fine pearlite and above those giving Martensite.
BANDED STRUCTURE
Appearance of a metal, under a microscope or viewed by the naked eye, on fractured or smoothed surfaces, with or without etching, showing parallel bands in the direction of rolling or working.
BAND SAW STEEL (WOOD)
A hardened tempered bright polished high carbon cold rolled spring steel strip produced especially for use in the manufacture of band saws for sawing wood, non ferrous metals, and plastics. Usually carries some nickel and with a Rockwell value of approximately C40/45.
BARK
Surface of metal, under the oxide3-scale layer, resulting from heating in an oxidizing environment. In the case of steel, such bark always suffers from decarburization.
BASE BOX
(See Tin Plate Base Box)
BASIC OPEN HEARTH4
(See Open Hearth Process)
BASIC OXYGEN PROCESS
A steel making process wherein oxygen of the highest purity is blown onto the surface of a bath of molten iron contained in a basic lined and ladle shaped vessel5. The melting cycle duration is extremely short with quality comparable to Open Hearth Steel.
BASIC PROCESS
A steel making process either Bessemer, open hearth or electric, in which the furnace is lined with a basic refractory6. A slag7, rich in lime, being formed and phosphorous removed.
BASIC STEEL
(See Basic Process)
BATH ANNEALING
Immersion in a liquid bath (such as molten lead or fused salts) held at an assigned temperature. When a lead bath is used, the process is known as lead annealing.
BAUXITE8
The only commercial ore of aluminum9, corresponding essentially10 to the formula Al2O3xH2O.
BEADING
Raising a ridge11 on sheet metal.
BEND TEST
Various tests used to determine the toughness and ductility of flat rolled metal sheet, strip or plate, in which the material is bent12 around its axis13 or around an outside radius14. A complete test might specify15 such a bend to be both with and against the direction of grain. For testing, samples should be edge filed to remove burrs and any edgewise cracks resulting from slitting17 or shearing18. If a vice19 is to be used then line the jaws20 with some soft metal or brass21, so as to permit a free flow of the metal in the sample being tested.
BERYLLIUM COPPER22
An alloy23 of copper and 2-3% beryllium with optionally fractional percentages of nickel or cobalt. Alloys24 of this series show remarkable25 age-hardening properties and an ultimate hardness of about 400 Brinell (Rockwell C43). Because of such hardness and good electrical conductivity, beryllium-copper is used in electrical switches, springs, etc.
BESSEMER PROCESS
A steel making process in which air is blown through the molten iron so that the impurities26 are thus removed by oxidation.
BILLET
(See Bloom)
BINARY27 ALLOY
An alloy containing two elements, apart from minor28 impurities, as brass containing the two elements copper and zinc29.
BLACK ANNEALING
A process of box annealing or pot annealing ferrous alloy sheet, strip or wire after hot working and pickling. (See Box Annealing)
BLACK OIL TEMPERED SPRING STEEL STRIP
(Scaleless Blue.) A flat cold rolled usually .70/.80% medium high carbon spring steel strip, blue-black in color, which has been quenched30 in oil and drawn31 to desired hardness. While it looks and acts much like blue tempered spring steel and carries a Rockwell hardness of C44/47, it has not been polished and is lower in carbon content. Used for less exacting32 requirements than clock spring steel, such as snaps, lock springs, hold down springs, trap springs, etc. It will take a more severe bend before fracture than will clock spring, but it does not have the same degree of spring-back.
BLACK PLATE
A light weight or a thin uncoated steel sheet or strip so called because of its dark oxide coloring prior to pickling. It is manufactured by two different processes. (1) From sheet bar on single stand sheet mills or sheer mills in tandem33. This method is now almost obsolete34. (2) On modern, high speed continuous tandem cold reduction mills from coiled hot rolled pickled wide strip into ribbon wound coils to finished gage35. Sizes range from 12” to 32” in width, and in thicknesses from 55 lbs. to 275 lbs. base box weight. It is used either as is for stampings, or may be enameled36 or painted or tin or terne coated.
BLAST FURNACE
A vertical37 shaft38 type smelting39 furnace in which an air blast is used, usually hot, for producing pig iron . The furnace is continuous in operation using iron ore, coke, and limestone40 as raw materials which are charged at the top while the molten iron and slag are collected at the bottom and are tapped out at intervals41.
BLAST BOX
(See Tin Plate Base Box)
BLISTER
A defect in metal produced by gas bubbles either on the surface or formed beneath the surface while the metal is hot or plastic. Very fine blisters42 are called “pin-head” or “pepper” blisters.
BLOOM
(Slab, Billet, Sheet-Bar.) Semifinished products, hot rolled from ingots. The chief differences are in their cross sectional areas in ratio of width to thickness, and in their intended use.
BLOOMING-MILL
A mill used to reduce ingots to blooms, billets, slabs43, sheet-bar etc. (See Semi-Finished Steel)
BLOWHOLE
A cavity produced during the solidification44 of metal by evolved gas, which in failing to escape is held in pockets.
BLUE ANNEALING
A process of softening45 ferrous alloys in the form of hot rolled sheet, by heating in the open furnace to a temperature within the transformation46 range and then cooling in air. The formation of bluish oxide on the surface is incidental.
BLUE BRITTLENESS
Reduced ductility occurring as a result of strain aging, when certain ferrous alloys are worked between 300?and 700癋. This phenomenon may be observed at the working temperature or subsequently at lower temperatures.
BLUE TEMPERED SPRING STEEL STRIPS
(See Tempered Spring Steel Strip)
BLUING
(1) Sheets - A method of coating sheets with a thin, even film of bluish-black oxide, obtained by exposure to an atmosphere of dry steam or air, at a temperature of about 1000癋, generally this is done during box-annealing. (2) Bluing of tempered spring steel strip; an oxide film blue in color produced by low temperature heating.
BODY-CENTERED
(Concerning space lattices.) Having the equivalent lattice points at the corners of the unit cell, and at its center; sometimes called centered or space-centered.
BONDERIZING
The coating of steel with a film composed largely of zinc phosphate in order to develop better bonding surface for paint or lacquer.
BORON
(Chemical Symbol B)- Element No. 5 of the periodic system. Atomic weight 10.82. It is gray in color, ignites at about 1112癋. and burns with a brilliant green flame, but its melting point in a non-oxidizing atmosphere is about 4000癋. Boron is used in steel in minute quantities for one purpose only - to increase the hardenability as in case hardening and to increase strength and hardness penetration47.
BOTTLE TOP MOLD
Ingot mold, with the top constricted48; used in the manufacture of “capped steel,” the metal in the constriction49 being covered with a cap fitted into the bottleneck50, which stops “rimming” action by trapping escaping gases.
BOW
(See Camber)
BOX ANNEALING
A process of annealing a ferrous alloy in a suitable closed metal container, with or without packing materials, in order to minimize oxidation. The charge is usually heated slowly to a temperature below the transformation range, but sometimes above or within it, and is then cooled slowly. This process is also called “close annealing” or “pot annealing.” (See Black Annealing)
BRAKE
A piece of equipment used for bending sheet: also called a “bar folder51.” If operated manually, it is called a “hand brake”; if power driven, it is called a “press brake.”
BRALE
A diamond penetrator, conical in shape, used with a Rockwell hardness tester for hard metals.
BRASS (Cartridge52)
Strip. 70% copper 30% zinc. This is one of the most widely used of the copper-zinc alloys; it is malleable53 and ductile54; has excellent cold-working; poor hot working and poor machining properties; develops high tensile strength with cold-working. Temper is impaired55 by cold rolling and classified in hardness by the number of B & S Gages of rolling (reduction in thickness) from the previous annealing gage. Rated excellent for soft-soldering; good for silver alloy brazing or oxyacetylene welding and fair for resistance of carbon arc welding. Used for drawn cartridges56, tubes, eyelet machine items, snap fasteners, etc.
BRASS SHIM
(See SHIM)
BRASS (Yellow)
Strip. 65% copper and 35% zinc. Known as “High Brass” or “Two to One Brass.” A copper-zinc alloy yellow in color. Formerly57 widely used but now largely supplanted58 by Cartridge Brass.
BRASSES
Copper base alloys in which zinc is the principal added element. Brass is harder and stronger than either of its alloying elements copper or zinc; it is malleable and ductile; develops high tensile with cold-working and not heat treatable for purposes of hardness development.
BRAZING
Joining metals by fusion59 of nonferrous alloys that have melting points above 800癋. but lower than those of the metals being joined. This may be accomplished60 by means of a torch (torch brazing), in a furnace (furnace brazing) or by dipping in a molten flux61 bath (dip or flux brazing). The filler metal is ordinarily in rod form in torch brazing; whereas in furnace and dip brazing the work material is first assembled and the filler metal may then be applied62 as wire, washers, clips, bands, or may be integrally bonded63, as in brazing sheet.
BREAK TEST
(For tempered steel) A method of testing hardened and tempered high carbon spring steel strip wherein the specimen64 is held and bent across the grain in a vice-like calibrated65 testing machine. Pressure is applied until the metal fractures at which point a reading is taken and compared with a standard chart of brake limitations for various thickness range. (See Bend Test)
BRIDLING
The cold working of dead soft annealed strip metal immediately prior to a forming, bending, or drawing operation. A process designed to prevent the formulation of Luder’s lines. Caution: Bridled66 metal should be used promptly67 and not permitted to (of itself) return to its pre-bridled condition.
BRIGHT ANNEALED WIRE
Steel wire bright drawn and annealed in controlled non-oxidizing atmosphere furnace.
BRIGHT ANNEALING
A process of annealing usually carried out in a controlled furnace atmosphere so that surface oxidation is reduced to a minimum and the surface remains68 relatively69 bright.
BRIGHT BASIC WIRE
Bright steel wire, slightly softer than Bright Bessemer Wire. Used for round head wood screws, bolts and rivets70, electric welded chain, etc.
BRIGHT BESSEMER WIRE
Stiff bright steel wire of hard drawn temper. Normally drawn to size without annealing. Used for nails, flat head wood screws, cheap springs, etc.
BRIGHT COMMERCIAL FINISH
(See Finishes)
BRIGHT DIP
An acid solution into which articles are dipped to obtain a clean, bright surface.
BRINELL HARDNESS (Test)
A common standard method of measuring the hardness of certain metals. The smooth surface of the metal is subjected to indentation by a hardened steel ball under pressure or load. The diameter of the resultant indentation, in the metal surface, is measured by a special microscope and the Brinell hardness value read from a chart or calculated formula.
BRITTLENESS
A tendency to fracture without appreciable71 deformation72.
BROACHING
Multiple shaving, accomplished by pushing a tool with stepped cutting edges along the work, particularly through holes.
BRONZE
Primarily an alloy of copper and tin but the name is now applied to other alloys not containing tin; e.g., aluminum, bronze, manganese bronze, and beryllium bronze. For varieties and uses of tin bronze see (Alpha Bronze and Phosphor Bronze).
BROWN & SHARPE GAGES (B & S)
A standard series of sizes arbitrarily indicated, as by numbers, to which the diameter of wire or thickness of sheet metal is usually made and which is used in the manufacture of brass, bronze, copper, copper-base alloys and aluminum. These gage numbers have a definite relationship to each other. By this system the decimal thickness is reduced by 50% every six gage numbers -while temper is expressed by the number of B S gage numbers as cold reduced in thickness from previous annealing. For each B & S gage number in thickness reduction, there is assigned a hardness value of ?hard. To illustrate73: One number hard = ?hard, two numbers hard = ?hard, etc.
BUCKLE
Alternate bulges74 or hollows recurring75 along the length of the product with the edges remaining relatively flat.
BURNING
Heating a metal beyond the temperature limits allowable for the desired heat treatment, or beyond the point where serious oxidation or other detrimental76 action begins.
BURNT
A term applied to a metal permanently77 damaged by overheating.
BURR
A thin ridge or roughness left by a cutting operation such as in metal slitting, shearing, blanking or sawing. This is common to a No. 3 slit16 edge in the case of steel.
BUTCHER SAW STEEL
A hardened, tempered, and bright polished high carbon spring steel strip (carbon content a bit higher than in wood band saw quality) with a Rockwell value of approximately C47/49.
BUTT WELDING
Joining two edges or ends by placing one against the other and welding them
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