Glossary of Terms

AGING The spontaneous change in the properties of a metal usually associated with the recovery of metal from an unstable condition produced by quenching (quenchaging) or by cold working (strainaging). Age hardening and aging are terms commonly used synonymously. See also "Precipitation Hardening."
AIR HARDENING (Air Quenching) A hardening process wherein the steel is heated to the hardening temperature and cooled in air. Unless steel is high in carbon or alloy, or both, it will not show much increase in hardness when air hardened.
ALLOY A material with metallic properties composed of two or more elements at least one of which is a metal.
ANNEALING Annealing generally refers to the heating and controlled cooling of solid material for the purpose of removing stresses, making it softer, refining its structure or changing its ductility, toughness or other properties. Specific heat treatments covered by the term annealing, blue annealing, box annealing, bright annealing, full annealing, graphitizing, malleablizing and process annealing.
AUSTEMPERING A patented heat treating process that consists of quenching an iron-base al loy from a temperature above the transformation range in a medium having a high rate of heat abstraction, and then maintaining the metal until transformation is complete, at a substantia lly uniform temperature which is below that of pearlite formation and above that of martensite.
AUSTENITE A phase in steels which consists of the gamma form of iron with carbon in solid solution . Austenite is tough, non-magnetic and tends to work-harden rapidly when cold worked in those steels which are austenitic at ordinary temperatures.
AUSTENITIC STEEL Steel which has a stable austenitic structure at normal (room) temperatures.
BEND TEST A test commonly made by bending a cold sample of specified size through a specified circular angle. Bend tests provide an indication of the ductility of the sample.
BRIGHT ANNEALING An annealing process usual ly carried out in a controlled furnace atmosphere so that surface oxidation is reduced to a minimum and the surface remains relatively bright.
BRINELL HARDNESS TEST This test consists of forcing a ball of standard diameter into the specimen being tested under standard pressure, and judging the hardness of the material by the amount of metal displaced.
CAMBER In sheet or strip: the greatest deviation of a side from a straight line. In structurals: the curvature from the plane of a flange in the length of the section, either leg of an angle being taken as the flange. (Also see Sweep.)
CARBO-NITRIDING A process of case hardening an ironbase alloy by the simultaneous absorption of carbon and nitrogen through heating in a gaseous atmosphere of suitable composition, followed by cooling at a rate that will produce desired properties.
CARBON RANGE In steel specifications, the carbon range is the difference between the minimum and maximum amount of carbon acceptable.
CARBON STEEL Steel whose major properties depend on its carbon content and in which other alloying elements are negligible.
CASE The su rface layer of an iron-base alloy which has been made substantial ly harder than the interior by the process of case hardening.
CASE HARDENING Carburizing, nitriding or cyaniding and subsequent hardening, by heat treatment, al l or part of the surface portions of a piece of iron base al loy.
CHARPY TEST A test made to determine the notched toughness, or impact strength, of a material. The test gives the energy required to break a standard notched specimen supported at the two ends.
CHEMICAL ANALYSIS Qualatative analysis consists of separating a substance into its component elements and identifying them. In quantitative ana lysis the proportion of all component elements are determined.
COINING A method of cold forming or sizing metal by compression, often used for imparting smooth finish and close tolerances.
COLD FINISHING Changing.the shape of, or reducing the cross section of steel while cold- usually accomplished by rolling, drawing through a die or turning.
COLD HEADING Forcing cold metal to flow into dies to form thicker sections and intricate shapes.
CREEP Plastic deformation or flow of metals held for long periods of time at stresses lower than normal yield strength. Especially important if temperature of stressing is near recrystallization temperature of the metal.
CREEP STRENGTH The maximum stress which can be applied to steel at a specified temperature without causing more than a specified percentage increase in length in a specified time.
DECARBURIZATION The loss of carbon from the surface of solid steel during heating, forging, hot rolling, etc.
DEEP DRAWING The process of working metal blanks in dies on a press into shapes which are usually more or less cup-li ke in character.
DIAMOND PYRAMID HARDNESS TEST An indentation hardness test employing a 136? diamond pyramid indenter and variable loads enabling the use of hardness scale for all ranges of hardness from soft lead to tungsten carbide.
DRAWING Drawing may refer to the pulling of steel through a die, as in drawing wire, or deforming steel in dies on a press (deep drawing.)
DUCTILITY The abil ity to permit change of shape without fracture. In steel, ductility is usually measured by elongation and reduction of area as determined in a tensile test.
EDDY-CURRENT TEST Nondestructive testing method in which eddy-current flow is induced in the test object. Changes in the flow caused by variation in the object are reflected into a nearby coi l or coils for subsequent analysis by suitable instrumentation and techniques.
EDGE CONDITION Mill Edge: Normal edge produced in rolling, conforms to no definite contour. Sheared Edge: One cut after rolling. Slit Edge: Produced when strip or coil is slit into multiple widths.
ELASTIC LIMIT The maximum load per unit of area (usually stated as pounds per square inch) that may be applied without producing permanent deformation. It is common practice to apply the load at a constant rate of increase and also measure the increase of length of the specimen at uniform load increments. The point at which the increase in length of the specimen ceases to bear a constant ratio to the increase in load, is ca lled the proportional limit.
ELONGATION The increase in length of a test specimen after rupture in a tensile test, expressed as a percentage of the original length.
FATIGUE TEST Highly polished samples are subject to stress while bending, which results in a reversal of stress for every complete revolution. The stress is reduced on each succeeding sample until the maximum stress a sample wil l sustain for ten million reversals has been reached. Since experience justifies the assumption that if steel can withstand ten million reversals, it can withstand such stress indefinitely. This stress is reported as the fatigue limit.
GALVANIZING Applying a coating of zinc to finished cold-reduced sheet or to fabricated parts made from strip products. Application may be by hot dip (either -..- hand or continuous) or electrolysis. .,r
GRAIN STRUCTURE The type of crysta lline structure as observed by eye or under the microscope.
HARDENABILITY (Of Steel) The ability of a steel to harden when cooled from its hardening temperature, as measured by its surface hardness and by the depth of hardening below the surface.
HARDENING (As applied to heat treatment of steel.) Heating and quenching to produce increased hardness.
HEAT RESISTING STEELS Those steels which are used for service at relatively high temperatures because they retain much of their strength and resist oxidation under such condition .
HEAT TREATMENT An operation or combination of operations involving the heating and cooling of steels in the solid state for the purpose of obtaining certain desirable mechanical, microstructural or corrosionresisting properties.
INTERGRANULAR CORROSION Electrochemical corrosion along the grain boundaries of an al loy, usually caused because the boundary regions conta in material anodic to the center of the grain.
MAGNETIC-ANALYSIS INSPECTION A nondestructive method of inspection for determining the existence and extent of possible defects in ferromagnetic materials. Finely divided magnetic particles, applied to the magnetized part, are attracted to and outline the pattern of any magnetic leakage fields created by discontinuities.
MARTENSITE With most steels, cooling as rapidly as possible from their quenching temperature develops a distinctive structure called martensite. In this form , the steel is at its maximum hardness.
MECHANICAL PROPERTIES Properties of a material that reveal the reaction when force is applied, or that involve the relationship between stress and strain, such as modulus of elasticity, tensile strength and fatigue limit. The term "mechanical properties" is preferred to" physical properties."
NICKEL STEEL Alloy steel containing nickel as its principal alloying element.
NITRIDING Adding nitrogen to the solid iron-base alloys by heating at a temperature below the critical in contact with ammonia or some other nitrogeneous material.
OIL QUENCH A quench from the hardening temperature, in which oil is the cooling medium.
PASSIVATION Generally refers to a process for the surface treatment of stainless steels. Material is subjected to the action of an oxidizing solution, usually nitric acid, which augments and strengthens the normal protective oxide film enabling the material to resist corrosive attack. The passivating process also removes foreign substances from the surface which might cause local corrosion .
PHYSICAL PROPERTIES Properties exclusive of those listed under mechanical properties such as density, electrica l conductivity and coefficient of thermal expansion. Term is often used to describe mechanical properties but such usage is not recommended.
PRECIPITATION HARDENING The process of hardening an alloy by heating it for the purpose of allowing a structural constituent to precipitate from a solid solution.
QUENCH HARDENING Hardening a ferrous alloy by heating within or above the transformation range and cooling at a controlled rate. This usually involves formation of martensite.
QUENCHING Cooling rapidly by immersion in oil, water, etc.
QUENCHING MEDIUM The medium used for cooling steel during heat treatment-usually oil, water, air, or sa lts.
QUENCHING TEMPERATURE The temperature from which steel is quenched during a heat treating process.
ROCKWELL HARDNESS TEST Forcing a cone-shaped diamond or hardened steel ball into the specimen being tested under standard pressure. The depth of penetration is an indication of the Rockwell Hardness.
ROLL THREADING Threading a bolt or screw by rolling it between two grooved die plates, one of which is in motion, or between rotating grooved circu lar rolls.
SHEAR STRENGTH The stress required to produce fracture in the plane of a cross section, the conditions of loading being such that the directions of force and of resistance are parallel and opposite although their paths are off set a specified minimum amount.
STRESS The load per unit area tending to deform a material.
TEMPERING Reheating after hardening to a temperature below the critical and then cooling.
TENSILE STRENGTH The maximum load per unit of original cross-sectional area obtained before rupture of a tensile specimen.
VICKERS HARDNESS TEST See "Diamond Pyramid Hardness Test. "
YIELD POINT The load per unit of original cross-section area at which a marked increase in the deformation of the specimen occurs without increase in load . Usually calculated from the load determined by the drop of the beam of the testing machine or by use of dividers.
YIELD STRENGTH The stress at which a material exhibits a specified deviation from proportionality of stress and strain. An offset of 0.2% is used for many metals.

APEX FASTENERS, Inc 15858 Business Center Drive Irwindale, CA 91706 USA
APEX Fasteners supplies standard and custom screws, nut retainers, shoulder screws, plastites and taptites, all types of rivets, spring steel fasteners and special stampings, sems screws in standard, fractional or metric to electronics, aviation and other OEM industries worldwide. custom manufactures screw machine components for electronic enclosure hardware as well as cold forming and cold headed specials for assembly and production requirements.
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