M – P
M B Grade
A term applied to Open-Hearth steel wire in the .45/.75 carbon range either hard drawn or oil tempered. Oil tempered wire of M B and W M B types are the most widely used of all spring wires. Oil tempered wire is more suitable to precision forming and casting operations than hard drawn wire, because of close control of tensile strength and superior straightness. . NOTE M B, H B and extra H B designate Basic Open Hearth steels, while W M B, W H B and extra W H B designate Acid Open Hearth Steels. The chemical composition and the mechanical properties are the same for both basic and acid steel.
Machinability
The capacity of a material to be machined easily.
Machinability Index
A relative measure of the machinability of an engineering material under specified standard conditions.
Machining
The cutting away of the surface of a metal by means of power driven machinery.
Macro-Etch
Etching of a metal surface for accentuation of gross structural details and defects for observation by the unaided eye or at magnifications not exceeding ten diameters.
Macroetch Test
Consists of immersing a carefully prepared section of the steel in hot acid and of examining the etched surface to evaluate the soundness and homogeneity of the product being tested.
Macrograph
A photographic reproduction of any object that has not been magnified more than ten times.
Macroscopic
Visible either with the naked eye or under low magnification (as great as about ten diameters.
Macrostructure
The structure of metal as revealed by macroscopic examination.
Magnetic-Particle 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, anre attracted to and outline the pattern of any magnetic-leakage fields created by discontinuities.
Magnetite
The oxide or iron of intermediate valence which has a composition close to the stoichiometric composition Fe3O4.
Malleability
The property that determines the ease of deforming a metal when the metal is subjected to rolling or hammering. The more malleable metals can be hammered or rolled into thin sheet more easily than others.
Malleabilizing
A process of annealing white cast iron in such a way that the combined carbon is wholly or partly transformed to graphitic or free carbon or, in someinstances, part of the carbon is removed completely.
Mandrel
A device used to retain the cavity in hollow metal products during working. A metal bar around other metal may be cast, bent, formed or shaped.
Mandrel Drawn
Used to obtain closer O.D. and I.D. tolerances, or O.D. and wall thickness tolerances. Available with improved mechanical properties.
Manganese
(Chemical symbol Mn.) Element No. 25 of the periodic system; atomic weight 54.93. Lustrous, reddish-white metal of hard brittle and, therfore, non-malleable character. The metal is used in large quantities in the form of Spiegel and Ferromanganese for steel manufacture as well as in manganese and many copper-base alloys. Its principal function is as an alloy in steel making: (1) It is ferrite-strengthening and carbide forming element. It increases hardenability inexpensively, with a tendency toward embrittlement when too high carbon and too high manganese accompany each other. (2) It counteracts brittleness from sulfur.
Manifold
A metal fitting with multiple apertures to direct liquid or gas.
Manual Welding
Welding where in the entire welding operation is performed and controlled by hand.
Martempering
Quenching an austenitized ferrous alloy in a medium at a temperature in the upper part of the martensite range, or slightly above that range, and holding it in the medium until the temperature throughout the alloy is substantially uniform. The alloy is then allowed to cool in air through the martensite range.
Martempering
(1) A hardening procedure in which an austenitized ferrous material is quenched into an appropriate medium at a temperature just above the Ms temperature of the material, held in the medium until the temperature is uniform through-out -but not long enough for bainite to form – and then cooled in air. The treatment is frequently followed by tempering. (2) When the process is applied to carburized material, the controlling Ms temperature is that of the case. This variation of the process is frequently called marquenching.
Martensite
A distinctive neddle like structure existing in steel as a transition stage in the transformation of austenite. It is the hardest constituent of steel of eutectoid composition. It is produced by rapid cooling from quenching temperature and is the chief constituent of hardened carbon tool steels. Martensite is magnetic.
Martensite Range
The interval between the Ms and Mf temperatures.
Matalloid
(a) Element intermediate in lustre and conductivity between the true metals and non-metals. Arsenic, antimony, boron, tellurium, and selenium, etc., are generally considered metalloids; frequently one allotropic modification of an element will be non-metallic, another metalloid in character. Obviously, no hard and fast line can be drawn. (b) In steel metallurgy, metalloid has a specialized, even if erroneous, meaning; it covers elements commonly prosent in simple steel; carbon, manganese, phosphorus, silicon and sulfur.
Matrix
The principal phase in which another constituent is embedded.
Matt or Matte Finish
(Steel) Not as smooth as normal mill finish. Produce by etched or mechanically roughened finishing rolls.
Mechanical Polishing
A method of producing a specularly reflecting surface by use of abrasives.
Mechanical Properties
The properties of a material that reveal its elastic and inelastic behavior where force is applied, thereby indicating its suitability for mechanical application; for example, modulus of elasticity, tensile strength, elongation, hardness, and fatigue limit.
Mechanical Spring
Any spring produced by cold forming from any material with or without subsequent heat treatment.
Mechanical Tubing
Used for a variety of mechanical and structural purposes, as opposed to pressure tubing, which is used to contain or conduct fluids or gases under pressure. It may be hot finished or cold drawn. It is commonly manufactured to consumer specifications covering chemical analysis and mechanical properties.
Mechanical Twin
A twin formed in a metal during plastic deformation by simple shear of the structure.
Mechanical Working
Plastic deformation or other physical change to which metal is subjected, by rolling, hammering, drawing., etc. to change its shape, properties or structure.
Medium-Carbon Steel
Contains from 0.30% to 0.60% carbon and less than 1.00% manganese. May be made by any of the standard processes.
Melting Point
The temperature at which a pure metal, compound or eutectic changes form solid to liquid; the temperature at which the liquid and the solid are in equilibrium.
Melting Range
The range of temperature in which an alloy melt; that is the range between solidus and liquidus temperatures.
Metal
An opaque, lustrous, elemental substance that is a good conductor of heat and electricity and, when polished, a good reflector or light. Most metals are malleable and ductile and are, in general, denser than other substances.
Metal Spraying
A process for applying a coating of metal to an object. The metal, usually in the form of wire, is melted by an oxyhydrogen or oxyacetylene blast or by an electric arc and is proficted at high speed by gas pressure against the object being coated.
Metallography
The science concerning the constituents and structure of metals and alloys as revealed by the microscope.
Metalograph
An optical instrument designed for both visual observation and photomicrography of prepared surfaces of opaque materials at magnifications ranging from about 25 to about 1500 diameters.
Metastable
Possessing a state of pseudo-equilibrium that has a free energy higher than that of the true equilibrium state but from which a system does not change spontaneously.
Mf Temperature
The temperature at which martensitic transformation is essentially complete during cooling after austenitization.
Microbands (deformation)
Thin sheet like volumes of constant thickness in which cooperative slip occurs on a fone scale. They are an instability which carry exclusively the deformation at medium strains when normal homogeneous slip is precluded. The sheets are aligned at +/- 55(degrees) to the compression direction and are confined to individual grains, which usually contain two sets of bands. Compare shear bands.
Microcrack
A crack of microscopic size.
Micrograph
A graphic reproduction of the prepared surface of a specimen at a magnification greater than ten diameters. When photographed, the reproduction is known as a photomicrograph (not a microphotograph).
Microstructure
The structure of polished and etched metal and alloy specimens as revealed by the microscope.
Mild Steel
Carbon steel containing a maximum of about 0.25% C.
Mill Edge
The edge of strip, sheet or plate in the as rolled state. Unsheared.
Mill Finish
A surface finish produced on sheet and plate. Characteristic of the ground finish used on the rolls in fabrication.
Mils
Units of measure equaling thousandths of an inch, thus 5 mils equals .005 inches.
Minimum Wall
Any wall having tolerances specified all on the plus side.
Modulus of Elasticity
A measure of the rigidity of metal. Ratio of stress, within proportional limit, to corresponding strain. Specifically, the modulus obtained in tension or compression is Young’s modulus, stretch modulus or modulus of extensibility; the modulus obtained in torsion or shear is modulus of rigidity, shear modulus or modulus of torsion; the modulus covering the ratio of the mean normal stress to the change in volume per unit volume is the bulk modulus. The tangent modulus and secant modulus are not restricted within the proportional limit; the former is the slope of the stress-strain curve at a specified point; the latter is the slope of a line from the origin to a specified point on the stress-strain curve. Also called elastic modulus and coefficient of elasticity.
Mold
A form of cavity into which molten metal is poured to produce a desired shape.
Molybdenum
(Chemical symbol Mo) Element No. 42 of the peridic system; atomic weight 95.95. Hard, tough metal of grayish-white color, becoming very ductile and malleable when properly treated at high temperatures; melting point 4748 (degrees) F.; boiling point about 6600 (degrees) F.; specific gravity 10.2 . Pure molybdenum can best be obtained as a black powder, by reduction of molybdenum trioxide or ammonium molybdate with hydrogen. From this powder, ductile sheet and wire are made by powder metallurgy techniques; these are used in radio and related work. Its principal functions as an alloy in steel making: (1) Raises grain-coarsening temperature of austenite. (2) Deepens hardening. (3) Counteracts tendency toward temperbrittleness. (4) Raises hot and creep strength, red hardness. (5) Enhances corrosion resistance in stainless steel. (6) Forms abrasion-resisting particles.
Ms Temperature
The temperature at which a martensitic transformation starts during cooling after austenitization.
Muntz Metal (A refractory Alloy)
Alpha-beta brass, 60% copper and 40% zinc. Stronger than alpha-brass and used for castings and hot-worked (rolled, stamped, or extruded) products. High strength brasses are developed from this by adding other elements.
Music Wire
A polished high tensile strength cold drawn wire with higher tensile strength and higher torsional strength than any other material available. These high mechanical properties are obtained by a combination of the high carbon content, the patenting treatment and by many continuous passes through drawing dies. The high toughness characteristic of this material is obtained by the patenting. Such wire is purchased according to tensile strength, not hardness.
Natural Aging
Spontaneous aging of a supersaturated solid solution at room temperature.
Necking
Local reduction of the cross-sectional area of metal by stretching.
Needle Cutter Steel
Usually supplied quarter hard rolled, extra precision rolled with sheared edges. Carbon content 1.25 – Chromium .15. Usually supplied in a 2 width from .002 to .035. Used for cutting the eyes of needle and milling the latch in a latch needle.
Nesting
(Nest) Laying out a cutting order by determining the ideal full-sized piece from which numerous cuts will be made, resulting in minimal or no scrap.
Network Structure
A structure in which the crystals of one constituent are surrounded by envelopes of another constituent which gives a network appearance to an etched test specimen.
Neumann Band
A mechanical (deformation) twin in ferrite.
Nickel
(Chemical symbol Ni) Element No. 28 of the periodic system; atomic weight 58.69. Silvery white, slightly magnetic metal, of medium hardness and high degree of ductility and malleability and resistance to chemical and atmospheric corrosion; melting point 2651 (degrees) F.; boiling point about 5250 (degrees) F., specific gravity 8.90. Used for electroplating. Used as an alloying agent, it is of great importance in iron-base alloys in stainless steels and in copper-base alloys such as Cupro-Nickel, as well as in nickel-base alloys such as Monel Metal. Its principal functions as an alloy in steel making: (1) Strengthens unquenched or annealed steels. (2) Toughens pearlitic-ferritic steels (especially at low temperature). (3) Renders high-chromium iron alloys austenitic.
Nickel Alloys
Metallic alloys containing at least 32% nickel.
Nickel Silver
Copper base alloys that contain 10-45% Zn. and 5-30% Ni.
Nickel Steel
Steel containing nickel as an alloying element. Varying amounts are added to increase the strength in the normalized condition to enable hardening to be performed in oil or air instead of water.
NiDI
Abbreviation for the Nickel Development Institute.
Niobium
(Chemical symbol Nb) Element No. 41 of the periodic system. See Columbium
Nitriding
Process of surface hardening certain types of steel by heating in ammonia gas at about 935-1000 (degrees) F., the increase in hardness being the result of surface nitride formation. Certain alloying constituents, principal among them being aluminum, greatly facilitate the hardening reaction. In general, the depth of the case is less than with carburizing.
Nitriding Steel
Steel which is particularly suited for the nitriding process, that is, it will form a very hard and adherent surface upon proper nitriding (heating in a partially dissociated atmosphere of ammonia gas). Composition usually .20-.40 carbon, .90-1.50 chromium, .15-1.00 molybdenum, and .85-1.20% aluminum.
Nitrogen
When used as an alloying element in stainless steels, it promotes strength and pitting resistance.
Nodular Pearlite
Pearlite that has grown as a colony with an approximately spherical morphology.
Nominal (NOM)
Name given to standard pipe designations 1/8 inch through 12 inches. Does not indicate actual I.D. or O.D. measurements. Wall thickness is also expressed as nominal.
Non-Destructive Testing
A method of detecting defects without destroying or permanently changing the material being tested. Test methods include ultrasonic, eddy current, magnetic particle, liquid, penetrant and X-ray.
Non-Ferrous Metals
Metals or alloys that are free of iron or comparatively so.
Non-Heat-Treatable Alloys
The correct and possibly the most definitive term for the 1XXX, the 3XXX, the 5XXX and some 8XXX alloy classes. These alloys gain strength through cold working and lose strength through thermal treatments. They are also called the soft or common alloys.
Non-Metallic Inclusions
Impurities (commonly oxides), sulphides, silicates or similar substances held in metals mechanically during solidification or formed by reactions in the solid state.
Non-Refractory Alloy
A term opposed to refractory alloy. A non-refractory alloy has malleability, that is, ease of flattening when subjected to rolling or hammering.
Non-Scalloping Quality Strip Steel
Strip steel ordered or sold on the basis of absence of unevenness, or ears, on the edges of the steel, when subjected to deep drawing.
Normalizing
Heating a ferrous alloy to a suitable temperature above the transformation range and then cooling in air to a temperature substantially below the transformation range.
Notch Brittleness
A measure of the susceptibility of a material to brittle fracture at locations of stress concentration. For example, in a notch tensile test a material is said to be notch brittle if its notch strength is less than its tensile strength; otherwise, it is said to be notch ductile.
Notch Sensitivity
A measure of the reduction in strength of a metal caused by the presence of stress concentration. Values can be obtained from static, impact or fatigue tests.
Notch Toughness
The ability of a metal to absorb sudden shock without fracturing.
Nucleation
Initiation of a phase transformation at discrete sites, the new phase growing from nuclei.
Nucleus
(1) The first structurally stable particle capable of initiating recrystallization of a phase or the growth of a new phase, and separated form the matrix by an interface. (2) The heavy central core of an atom, in which most of the mass and the total positive electrical charge are concentrated.
Number as Pertaining to Hardness
In copper base alloys inductry; temper is referred to as so many numbers hard, i.e. Yellow Brass Half Hard is termed 2 numbers hard. This term is derived from terminology used on the mill gloor where by temper or hardness is imparted by cold working and classified as to hardness by the number of Brown & Sharpe gages away from the soft or as-annealed state.
Oil Hardening
A process of hardening a ferrous alloy of suitable composition by heating within or above the transformation range and quenching in oil.
Oil Stain Aluminum
Stain produced by the incomplete burning of the lubricants on the surface of the sheet. Rolling subsequent to staining will change color from darker browns to lighter browns down to white.
Oil-Hardening Steel
Steel adaptable to hardening by heat treatment and quenching in oil.
Olsen (Ductility) Test
A method of measuring the ductility and drawing properties of strip or sheet metal which involves determination of the width and depth of impression. The test simulating a deep drawing operation is made by a standard steel ball under pressure, continuing until the cup formed from the metal sample fractures. Readings are in thousandths of an inch. This test is sometimes used to detect stretcher straining and indicates the surface finish after drawing, similar to the Erichsen ductility test.
Open Surface
Rough surface on black plate, sheet or strip, resulting from imperfection in the original steel bars from which the plate was rolled.
Open-Hearth Process
Process of making steel by heating the metal in the hearth of a regenerative furnace. In the basic open-hearth steel process, the lining of the hearth is basic, usually magnesite; whereas in the acid open-hearth steel process, an acid material, silica, is used as the furnace lining and pig iron, extremely low in phosphorous (less than 0.04%), is the raw material charged in.
Orange Peel
A pebble-grain surface which develops in forming of metals having coarse grains.
Orange Peel (effect)
A surface roughening (defect) encountered in forming products from metal stock that has a coarse grain size. It is due to uneven flow or to the appearance of the overly large grains usually the result of annealing at too high a temperature. Also referred to as pebbles and alligator skin.
Ore
A mineral from which metal is (or may be) extracted.
Orientation (crystal)
Arrangement of certain crystal axes or crystal planes in a crystalline aggregate with respect to a given direction or plane. If there is any tendency for one arrangement to predominate, it is known as the preferred orientation; in the absence of any such preference, random orientation exists.
Oscillated Wound or Scroll Wound
A method of even winding metal strip or wire on to a reel or mandrel wherein the strands are uniformly over-lapped. Sometimes termed stagger wound or vibrated wound. The opposite of ribbon wound.
Ovality
The difference between the maximum and minimum outside diameters of any one cross section of a tube. It is a measure of deviation from roundness.
Overaging
Aging under conditions of time and temperature greater than those required to obtain maximum change in a certain property.
Overheating
Heating a metal or alloy to such a high temperature that its properties are impaired. When the original properties cannot be restored by further heat treating, by mechanical working or by a combination of working and heat treating, the overheating is known as burning.
Oxidation
The addition of oxygen to a compound. Exposure to atmosphere sometimes results in oxidation of the exposed surface, hence a staining or discoloration. This effect is increased with temperature increase.
Oxide
Compound of oxygen with another element.
Oxidized Surface
A surface having a thin, tightly adhering oxidized skin.
Oxygen Lance
A length of pipe used to convey oxygen onto a bath of molten metal.
Oxygen-Free Copper
Electrolytic copper free from cuprous oxide, produced without the use of residual metallic or metalloidal deoxidizers.
Pack Rolling
Rolling two or more pieces of thin sheet at the same time, a method usually practiced in rolling sheet into thin foil.
Pack Rolling
Hot rolling a pack of two or more sheets of metal; scale prevents the sheets from being welded together.
Pancake Forging
A rough forged shape which may be obtained quickly with a minimum of tooling. It usually requires considerable machining to attain the finish size.
Pancake Grain Structure
A structure in which the lengths and widths of individual grains are large compared to their thicknesses.
Paper Interleaved
To prevent damage to the surface during shipment, handling or storage, the material is frequently coiled with a large roll of paper paid off at the same time so that between each wrap of metal there is a wrap of paper. This paper between the steel wraps prevents the surfaces of the metal from rubbing against each other that may spoil the surface.
Partial Annealing
Thermal treatment given cold worked metal to reduce the strength to a controlled level.
Pass
A term indicating the process of passing metal through a rolling mill.
Passivation
The changing of the chemically active surface of a metal to a much less reactive state. Contrast with activation.
Passivate
The changing of the chemically active surface of a metal to a much less active state by the application of the proper chemical treatment or by applying an induced electrical current and voltage for cathodic or anodic protection from corrosion. An example of chemically passivating stainless steel would be to immerse stainless in a hot solution of approximately 10 to 20 percent by volume nitric acid and water.
Patenting
A heat treatment applied to medium and high-carbon steel prior to cold drawing to wire. The treatment involves austenitization followed by isothermal transformation at a temperature that produces a microstructure of very fine pearlite.
Pattern Welding
A process in which strips or other small sections of iron or steel are twisted together and then forge welded. Homogeneity and toughness are thereby improved. A regular decorative pattern can be developed in the final product. COmmonly used for making swords as early as the 3rd century A.D.
Patterned or Embossed Sheet
A sheet product on which a raised or indented pattern has been impressed on either on or both surfaces by the use of rolls.
Pearlite
A eutectoid transformation product of ferrite and cementite that ideally has a lamellar structure but that is always degenerate to some extent.
Pearlite
Lamellar structure resembling mother of pearl. A compound of iron and carbon occurring in steel as a result of the transformation of austenite into aggregations of ferrite and iron carbide.
Peening
Mechanical working of metal by hammer blows or shot impingement.
Penetrant Inspection
A method of non-destructive testing for determining the existence and extent of discontinuities that are open to the surface in the part being inspected. The indications ore made visible through the use of a dye or fluorescent chemical in the liquid employed as the inspection medium.
Penetration Rate
Generally expressed in mils per year, this rate measures the amount of corrosion on a given metal by a given environment.
Peritectic
An isothermal reversible reaction in which a liquid phase reacts with a solid phase to produce another solid phase.
Permalloy
Nickel alloys containing about 20 to 60% Fe, used for their high magnetic permeability and electrical resistivity.
Permanent Set
Non-elastic or plastic, deformation of metal under stress, after passing the elastic limit.
pH Balance
A scale with values from zero to 14, with 7 representing neutrality, zero represents greatest acidity, and 14 represents greatest alkalinity.
Phase
A physically homogeneous and distincy portion of a material system.
Phase Diagram
Synonymous with constitutional diagram.
Phosphor Bronze
Copper base alloys, with 3.5 to 10% of tin, to which has been added in the molten state phosphorus in varying amounts of less than 1% for deoxidizing and strengthening purposes. Because of excellent toughness, strength, fine grain, resistance to fatigue and wear, and chemical resistance, these alloys find general use as springs and in making fittings. It has corrosion resisting properties comparable to copper.
Phosphor Bronze Strip
A copper-base alloy containing up to 10% tin, which has been deoxidized with phosphorus in varying amounts of less than 1%. Temper is imparted by cold rolling, resulting in greater tensile strength and hardness than in most copper-base alloys or either of its alloying elements copper or tin. The various tempers from One Number Hard to Ten Numbers Hard are classified in hardness by the number of B&S Gages reduction in dimension from the previous soft or as-annealed state. Phosphor Bronze is not heat treatable for purposes of hardness development. It does not withstand elevated temperatures very well and should not be used in service above 225 (degrees) F. even after stress relieving treatment at 325 (degrees) to 350 (degrees) F. It has excellent electrical properties, corrosion resistant comparable to copper; great toughness and resistance to fatigue. Rated good for soft soldering, silver alloy brazing, oxyacetylene, carbon arc and resistance welding.
Phosphorus
(Chemical symbol P) Element No. 15 of the periodic system; atomic weight 30.98. Non-metallic element occurring in at least three allotropic forms; melting point 111 (degrees) F.; boiling point 536 (degrees) F.; specific gravity 1.82. In steels it is usually undesirable with limits set in most specifications. However, it is specified as an alloy in steel to prevent the sticking of light-gage sheets; to a degree it strengthens low carbon steel; increases resistance to corrosion, and improves machinability in free-cutting steels. In the manufacture of Phosphor Bronze it is used as a deoxidizing agent.
Photomicrograph
A photographic reproduction of any object magnified more than ten diameters. The term micrograph may be used.
Physical Properties
Properties other than mechanical properties, that pertain to the physical nature of a material; e.g., density, electrical conductivity, thermal expansion, reflectivity, magnetic susceptibility, etc.
Pickling
Removing surface oxides from metals by chemical or electrochemical reaction.
Pickling Patch
A defect in tin plate, galvanized or terne plated steel due to faulty pickling, leaving areas from which the oxide has not been completely removed.
Piercing
A seamless tubemaking method in which a hot billet is gripped and rotated by rolls or cones and directed over a piercer point which is held on the end of a mandrel bar.
Pig Iron
(1) High-carbon iron made by reduction of iron ore in the blast furnace. (2) Cast iron in the form of pigs.
Piling
A process in which several bars are stacked and hot rolled together with the objective of improving the homogeneity of the final product. Used in primitive iron making.
Pin Expansion Test
A test for determining the ability of tubes to be expanded or for revealing the presence of cracks or other longitudinal weaknesses, made by forcing a tapered pin into the open end of a tube.
Pinchers
Long fern like creases usually diagonal to the direction of rolling.
Pinholes
Microscopic imperfection of the coatings, that is, microscopic bare spots, also microscopic holes penetrating through a layer or thickness of light gage metal.
Pipe
(1) The central cavity formed by contraction in metal, especially ingots, during solidification. (2) The defect in wrought or cast products resulting from such a cavity. (3) An extrusion defect due to the oxidized surface of the billet flowing toward the center of the rod at the back end. (4) A tubular metal product, cast or wrought.
Pit (defect)
A sharp depresssion in the surface of the metal.
Pitting
Forming small sharp cavities in a metal surface by nonuniform electro-deposition or by corrosion.
Planimetric Method
A method of measuring grain size, in which the grains within a definite area are counted.
Planishing
Producing a smooth surface finish on metal by rapid succession of blows delivered by highly polished dies or by a hammer designed for the purpose, or by rolling in a planishing mill.
Plasma Arc Cutting
Basically a method of cutting by means of a jet torch flame which operates at extremely high temperatures (up to 30,000 F): thereby, giving a clean edge which is suitable for welding and which avoids “carbide precipitation in stainless.
Plastic Deformation
Deformation that remains, or will remain, permanent after release of the stress that caused it.
Plasticity
The ability of a metal to be deformed extensively without rupture.
Plate
A flat-rolled metal product of some minimum thickness and width argitrarily dependent on the type of metal.
Plate Martensite
Martensite formed, partly in steels containing more than about 0.5% C and solely in steels containing more than about 1.0% C, as lenticular-shape plates on irrational habit planes that are near (225)A, or {259}A in very-high-carbon steels
Plating
A thin coating of metal laid on another metal.
Plating Quality
Internal cleanliness and surface finish suitable for plating with nickel, chromium, etc.
Plug
A rod or mandrel that fills a tube as it is drawn through a die.
Polished Surface
The finish obtained by buffing with rouge or similar fine abrasive, resulting in a high gloss or polish.
Polishing
Producing a specularly reflecting surface.
Polycrystalline
Comprising an aggregate of more than one crystal, and usually a large number of crystals.
Polymorphism
The property whereby certain substances may exist in more than one crystalline form, the particular form depending on the conditions of crystallization – e.g., temperature and pressure. Among elements, this phenomenon is also called allotropy.
Postheating
Heating weldments immediately after welding, for tempering, for stress relieving, or for providing a controlled rate of cooling to prevent formation of a hard or brittle structure.
Pot
A vessel for holding molten metal. Also used to refer to the electrolytic reduction cell employed in winning certain metals, such as aluminum, from a fused electrolyte.
Pot Annealing
Is the same as box annealing.
Pounds Per Inch of Width (P.I.W.)
Pounds per inch of width refers to the weight of a one-inch multiple of coil. To determine the PIW, divide the weight of the coil by its width in inches.
Pouring
The transfer of molten metal from the ladle into ingot molds or other types of molds; for example, in castings.
Powder Metallurgy
The art of producing metal powders and of utilizing metal powders for the production of massive materials and shaped objects.
Precipitation
The separation of a substance from a solution or suspension by chemical or thermal change.
Precipitation Hardening
A process of hardening an alloy in which a constituent precipitates from a supersaturated solid solution.
Preferred Orientation
A condition of a polycrystalline aggregate in which the crystal orientations are not random.
Preheating
Heating before some further thermal or mechanical treatment. For tool steel, heating to an intermediate temperature immediately before austenitizing. For some nonferrous alloys, heating to a high temperature for a long time, in order to homogenize the structure before working.
Press Forging
Forging metal, usually hot, between dies in a press.
Pressure Tubing
Used for the conduction of fluids under pressures, i.e. condenser tubes.
Pressure Vessels
A fabricated metal structure used to contain or convey gases, liquids and other substances under pressure.
Primary Crystal
The first type of crystal that separates from a melt during solidifacation.
Primes
Metal products, principally sheet and plate, of the highest quality and free from visible defects.
Process Annealing
In the sheet and wire industries, heating a ferrous alloy to a temperature close to, but below, the lower limit of the transformation range and then cooling, in order to soften the alloy for futher cold working.
Proeutectoid (phase)
Particles of a phase that precipitate during cooling after austenitizing but before the eutectoid transformation takes place.
Progressive Aging
An aging process in which the temperature of the alloy is continuously increased during the aging cycle. The temperature may be increased in steps or by any other progressive method. Compare with interrupted aging.
Proof Stress
(1) The stress that will cause a specified small permanent set in a material. (2) A specified stress to be applied to a member or structure to indicate its ability to withstand service loads.
Propertional Limit
The greatest stress that the material is capable of sustaining without a deviation from the law of proportionally of stress to strain (Hooke’s Law).
P.S.I.
Pounds per square inch
Puddling Process
A process for making wrought iron in which cast orn is melted in a hearth furnace and rabbled with slag and oxide until a pasty mass is obtained. This process was developed by Henry Cort about 1784 and remained in use until 1957, although on a very small scale during the present century.
Pulse-Echo Method
A nondestructive test in which pulses of energy are directed onto a part, and the time for the echo to return from one or more reflecting surfaces is measured.
Punch
The movable part that forces the metal into the die in equipment for sheet drawing, blanking, coining, embossing and the like.
Punching
Shearing holes in sheet metal with punch and die.
Pyrometer
An instrument of any of various types used for measuring temperatures.