ASM Metals Handbook - Desk Edition (ASM_ 1998) Episode 15 pot

2 The capacity of a material, by virtue of high yield strength and low elastic modulus, to exhibit considerable elastic recovery o resistance brazing o A brazing process in which the he

o reducing flame

o (1) A gas flame produced with excess fuel in the inner flame (2) A gas flame resulting from combustion of a mixture containing too much fuel or too little air See also neutral flame and oxidizing flame

o reduction

o (1) In cupping and deep drawing, a measure of the percentage decrease from blank diameter to cup diameter, or of diameter reduction in redrawing (2) In forging, rolling, and drawing, either the ratio of the original to final cross-sectional area or the percentage decrease in cross-sectional area (3) A reaction in which there is a decrease in valence resulting from a gain in electrons Contrast with oxidation

o reduction cell

o A pot or tank in which either a water solution of a salt or a fused salt is reduced electrolytically to form free metals or other substances

o reduction in area (RA)

o The difference between the original cross-sectional area of a tensile specimen and the smallest area at or after fracture as specified for the material undergoing testing Also known as reduction

of area

o reel

o (1) A spool or hub for coiling or feeding wire or strip (2) To straighten and planish a round bar

by passing it between contoured rolls

o refractory

o (1) A material (usually an inorganic, nonmetallic, ceramic material) of very high melting point with properties that make it suitable for such uses as furnace linings and kiln construction (2) The quality of resisting heat

o regenerator

o Same as recuperator except that the gaseous products or combustion heat brick checkerwork in a chamber connected to the exhaust side of the furnace while the incoming air and fuel are being heated by the brick checkerwork in a second chamber, connected to the entrance side At intervals, the gas flow is reversed so that incoming air and fuel contact hot checkerwork while that in the second chamber is being reheated by exhaust gases

o residual elements

o Small quantities of elements unintentionally present in an alloy

o residual stress

o (1) The stress existing in a body at rest, in equilibrium, at uniform temperature, and not subjected

to external forces Often caused by the forming or thermal processing curing process (2) An internal stress not depending on external forces resulting from such factors as cold working, phase changes, or temperature gradients (3) Stress present in a body that is free of external forces or thermal gradients (4) Stress remaining in a structure or member as a result of thermal

or mechanical treatment or both Stress arises in fusion welding primarily because the weld metal contracts on cooling from the solidus to room temperature

o resilience

o (1) The amount of energy per unit volume released on unloading (2) The capacity of a material,

by virtue of high yield strength and low elastic modulus, to exhibit considerable elastic recovery

o resistance brazing

o A brazing process in which the heat required is obtained from the resistance to electric current flow in a circuit of which the workpiece is a part

o resistance seam welding

o A resistance welding process that produces coalescence at the faying surfaces of overlapped parts progressively along a length of a joint The weld may be made with overlapping weld nuggets, a continuous weld nugget, or by forging the joint as it is heated to the welding temperature by resistance to the flow of the welding current

o resistance soldering

o A soldering process in which the heat required is obtained from the resistance to electric current flow in a circuit of which the workpiece is a part

o resistance spot welding

o A resistance welding process that produces coalescence at the faying surfaces of a joint by the heat obtained from resistance to the flow of welding current through the workpieces from electrodes that serve to concentrate the welding current and pressure at the weld areas

o resistance welding

o A group of welding processes that produce coalescence of metals with resistance heating and pressure See also flash welding , projection welding , resistance seam welding , and resistance spot welding

o resistance welding electrode

o The part(s) of a resistance welding machine through which the welding current and, in most cases, force are applied directly to the work The electrode may be in the form of a rotating wheel, rotating bar, cylinder, plate, clamp, chuck, or modification thereof

o restraint

o Any external mechanical force that prevents a part from moving to accommodate changes in dimension due to thermal expansion or contraction Often applied to weldments made while clamped in a fixture Compare with constraint

o restriking

o (1) The striking of a trimmed but slightly misaligned or otherwise faulty forging with one or more blows to improve alignment, improve surface condition, maintain close tolerances, increase hardness, or effect other improvements (2) A sizing operation in which coining or stretching is used to correct or alter profiles and to counteract distortion (3) A salvage operation following a primary forging operation in which the parts involved are rehit in the same forging die in which the pieces were last forged

o Casting of a continuously stirred semisolid metal slurry The process involves vigorous agitation

of the melt during the early stages of solidification to break up solid dendrites into small spherulites See also semisolid metal forming

o rimmed steel

o A low-carbon steel containing sufficient iron oxide to give a continuous evolution of carbon monoxide while the ingot is solidifying, resulting in a case or rim of metal virtually free of voids Sheet and strip products made from rimmed steel ingots have very good surface quality

o ring and circle shear

o A cutting or shearing machine with two rotary-disk cutters driven in unison and equipped with a circle attachment for cutting inside circles or rings from sheet metal, where it is impossible to start the cut at the edge of the sheet One cutter shaft is inclined to the other to provide cutting clearance so that the outside section remains flat and usable See also circle shear and rotary shear

o ring rolling

o The process of shaping weldless rings from pierced disks or shaping thick-wall ring-shaped blanks between rolls that control wall thickness, ring diameter, height, and contour

o river pattern

o A term used in fractography to describe a characteristic pattern of cleavage steps running parallel

to the local direction of crack propagation on the fracture surfaces of grains that have separated

o An extra cathode or cathode extension that reduces the current density on what would otherwise

be a high-current-density area on work being electroplated

o Rochelle copper

o (1) A copper electrodeposit obtained from copper cyanide plating solution to which Rochelle salt (sodium potassium tartrate) has been added for grain refinement, better anode corrosion, and cathode efficiency (2) The solution from which a Rochelle copper electrodeposit is obtained

o rock candy fracture

o A fracture that exhibits separated-grain facets; most often used to describe an intergranular fracture in a large-grained metal

o rocking shear

o A type of guillotine shear that utilizes a curved blade to shear sheet metal progressively from side

to side by a rocker motion

o Rockwell hardness number

o A number derived from the net increase in the depth of impression as the load on an indenter is increased from a fixed minor load to a major load and then returned to the minor load Various scales of Rockwell hardness numbers have been developed based on the hardness of the materials

to be evaluated The scales are designated by alphabetic suffixes to the hardness designation For example, 64 HRC represents the Rockwell hardness number of 64 on the Rockwell C scale See also Rockwell superficial hardness number

o Rockwell hardness test

o An indentation hardness test using a calibrated machine that utilizes the depth of indentation, under constant load, as a measure of hardness Either a 120° diamond cone with a slightly rounded point or a 1.6 or 3.2 mm ( or in.) diam steel ball is used as the indenter

o Rockwell superficial hardness number

o Like the Rockwell hardness number, the superficial Rockwell number is expressed by the symbol

HR followed by a scale designation For example, 81 HR30N represents the Rockwell superficial hardness number of 81 on the Rockwell 30N scale

o Rockwell superficial hardness test

o The same test as used to determine the Rockwell hardness number except that smaller minor and major loads are used In Rockwell testing, the minor load is 10 kgf, and the major load is 60, 100,

or 150 kgf In superficial Rockwell testing, the minor load is 3 kgf, and major loads are 15, 30, or

45 kgf In both tests, the indenter may be either a diamond cone or a steel ball, depending principally on the characteristics of the material being tested

o Curving sheets, bars, and sections by means of rolls See also bending rolls

o roll compacting

o Progressive compacting of metal powders by use of a rolling mill

o roller hearth furnace

o A modification of the pusher-type continuous furnace that provides for rollers in the hearth or muffle of the furnace whereby friction is greatly reduced and lightweight trays can be used repeatedly without risk of unacceptable distortion and damage to the work See also pusher furnace

o roller leveler breaks

o Obvious transverse breaks usually about 3 to 6 mm ( to in.) apart caused by the sheet metal fluting during roller leveling These will not be removed by stretching

o roller leveler lines

o Same as leveler lines

o roller leveling

o Leveling by passing flat sheet metal stock through a machine having a series of small-diameter staggered rolls that are adjusted to produce repeated reverse bending

o roller stamping die

o An engraved roller used for impressing designs and markings on sheet metal

o rolling mills

o Machines used to decrease the cross-sectional area of metal stock and to produce certain desired shapes as the metal passes between rotating rolls mounted in a framework comprising a basic unit called a stand Cylindrical rolls produce flat shapes; grooved rolls produce rounds, squares, and structural shapes See also four-high mill , Sendzimir mill , and two-high mill

o roll straightening

o The straightening of metal stock of various shapes by passing it through a series of staggered rolls, the rolls usually being in horizontal and vertical planes, or by reeling in two-roll straightening machines

o rotary forging

o A process in which the workpiece is pressed between a flat anvil and a swiveling (rocking) die with a conical working face; the platens move toward each other during forging Also called orbital forging Compare with radial forging

o rotary retort furnace

o A continuous-type furnace in which the work advances by means of an internal spiral, which gives good control of the retention time within the heated chamber

o rotary shear

o A sheet metal cutting machine with two rotating-disk cutters mounted on parallel shafts driven in unison

o rotary swager

o A swaging machine consisting of a power-driven ring that revolves at high speed, causing rollers

to engage cam surfaces and force the dies to deliver hammerlike blows on the work at high frequency Both straight and tapered sections can be produced

o rubber forming

o Forming a sheet metal wherein rubber or another resilient material is used as a functional die part Processes in which rubber is employed only to contain the hydraulic fluid are not classified as rubber forming

o rubber-pad forming

o A sheet metal forming operation for shallow parts in which a confined, pliable rubber pad attached to the press slide (ram) is forced by hydraulic pressure to become a mating die for a punch or group of punches placed on the press bed or baseplate Also known as the Guerin process Variations of the Guerin process include the fluid-cell process , fluid forming , and Marforming process

o rubber wheel

o A grinding wheel made with a rubber bond

o runner

o (1) A channel through which molten metal flows from one receptacle to another (2) The portion

of the gate assembly of a casting that connects the sprue with the gate(s) (3) Parts of patterns and finished castings corresponding to the portion of the gate assembly described in (2)

o runner box

o A distribution box that divides molten metal into several streams before it enters the casting mold cavity

o salt bath heat treatment

o Heat treatment for metals carried out in a bath of molten salt

o salt fog test

o An accelerated corrosion test in which specimens are exposed to a fine mist of a solution usually containing sodium chloride, but sometimes modified with other chemicals Also known as salt spray test

o salt spray test

o See salt fog test

o sample

o (1) One or more units of a product (or a relatively small quantity of a bulk material) withdrawn from a lot or process stream and then tested or inspected to provide information about the properties, dimensions, or other quality characteristics of the lot or process stream (2) A portion

of a material intended to be representative of the whole

o sand

o A granular material naturally or artificially produced by the disintegration or crushing of rocks or mineral deposits In casting, the term denotes an aggregate, with an individual particle (grain) size of 0.06 to 2 mm (0.002 to 0.08 in.) in diameter, that is largely free of finer constituents, such

as silt and clay, which are often present in natural sand deposits The most commonly used foundry sand is silica; however, zircon, olivine, aluminum silicates, and other crushed ceramics are used for special applications

contains a layer of sand; defect common to thin-wall portions of the casting or around hot areas

o scaling

o (1) Forming a thick layer of oxidation products on metals at high temperature Scaling should be distinguished from rusting, which involves the formation of hydrated oxides See also rust (2) Depositing water-insoluble constituents on a metal surface, as in cooling tubes and water boilers

o scalping

o Removing surface layers from an ingot, billet, or slab

o scanning Auger microscopy (SAM)

o An analytical technique that measures the lateral distribution of elements on the surface of a material by recording the intensity of their Auger electrons versus the position of the electron beam

o scarfing

o Cutting surface areas of metal objects, ordinarily by using an oxyfuel gas torch The operation permits surface imperfections to be cut from ingots, billets, or the edges of plate that are to be beveled for butt welding See also chipping

o Scleroscope hardness number (HSc or HSd)

o A number related to the height of rebound of a diamond-tipped hammer dropped on the material being tested It is measured on a scale determined by dividing into 100 units the average rebound

of the hammer from a quenched (to maximum hardness) and untempered AISI W-5 tool steel test block

o Scleroscope hardness test

o A dynamic indentation hardness test using a calibrated instrument that drops a diamond-tipped hammer from a fixed height onto the surface of the material being tested The height of rebound

of the hammer is a measure of the hardness of the material

o scouring

o (1) A wet or dry cleaning process involving mechanical scrubbing (2) A wet or dry mechanical finishing operation, using fine abrasive and low pressure, carried out by hand or with a cloth or wire wheel to produce satin or butler-type finishes

o scrap

o (1) Products that are discarded because they are defective or otherwise unsuitable for sale (2) Discarded metallic material, from whatever source, that may be reclaimed through melting and refining

o screw dislocation

o seal coat

o Material applied to infiltrate the pores of a thermal spray deposit

o sealing

o (1) Closing pores in anodic coatings to render them less absorbent (2) Plugging leaks in a casting

by introducing thermosetting plastics into porous areas and subsequently setting the plastic with heat

o seam weld

o A continuous weld made between or upon overlapping members, in which coalescence may start and occur on the faying surfaces, or may have proceeded from the outer surface of one member The continuous weld may consist of a single weld bead or a series of overlapping spot welds

o secondary ion mass spectroscopy (SIMS)

o An analytical technique that measures the masses of ions emitted from the surface of a material when exposed to a beam of incident ions The incident ions are usually monoenergetic and are all

of the same species, for example, 5 keV Ne+ ions

o segregation banding

o Inhomogeneous distribution of alloying elements aligned in filaments or plates parallel to the direction of working

o seizing

o The stopping of a moving part by a mating surface as a result of excessive friction

o seizure

o The stopping of relative motion as the result of interfacial friction Seizure may be accompanied

by gross surface welding The term is sometimes used to denote scuffing

o Any solid material that shows low friction without application of a lubricant

o semiautomatic arc welding

o Arc welding with equipment that controls only the filler metal feed The advance of the welding

o semifinisher

o An impression in a series of forging dies that only approximates the finish dimensions of the forging Semifinishers are often used to extend die life or the finishing impression, to ensure proper control of grain flow during forging, and to assist in obtaining desired tolerances

o semikilled steel

o Steel that is incompletely deoxidized and contains sufficient dissolved oxygen to react with the carbon to form carbon monoxide and thus offset solidification shrinkage

o semipermanent mold

o A permanent mold in which sand cores or plaster are used

o semisolid metal forming

o A two-step casting/forging process in which a billet is cast in a mold equipped with a mixer that continuously stirs the thixotropic melt, thereby breaking up the dendritic structure of the casting into a fine-grained spherical structure After cooling, the billet is stored for subsequent use Later,

a slug from the billet is cut, heated to the semisolid state, and forged in a die Normally the cast billet is forged when 30 to 40% is in the liquid state See also rheocasting

o sensitization

o In austenitic stainless steels, the precipitation of chromium carbides, usually at grain boundaries,

on exposure to temperatures of about 540 to 845 °C (about 1000 to 1550 °F), leaving the grain

boundaries depleted of chromium and therefore susceptible to preferential attack by a corroding medium Welding is the most common cause of sensitization Weld decay (sensitization) caused

by carbide precipitation in the weld heat-affected zone leads to intergranular corrosion

o sensitizing heat treatment

o A heat treatment, whether accidental, intentional, or incidental (as during welding), that causes precipitation of constituents at grain boundaries, often causing the alloy to become susceptible to intergranular corrosion or intergranular stress-corrosion cracking See also sensitization

o Sendzimir mill

o A type of cluster mill with small-diameter work rolls and larger-diameter backup rolls, backed up

by bearings on a shaft mounted eccentrically so that it can be rotated to increase the pressure between the bearing and the backup rolls Used to roll precision and very thin sheet and strip

o series welding

o Resistance welding in which two or more spot, seam, or projection welds are made simultaneously by a single welding transformer with three or more electrodes forming a series circuit

o settling

o (1) Separation of solids from suspension in a fluid of lower density, solely by gravitational effects (2) A process for removing iron from liquid magnesium alloys by holding the melt at a low temperature after manganese has been added to it

o severity of quench

o Ability of quenching medium to extract heat from a hot steel workpiece; expressed in terms of the Grossmann number (H)

o shadowing

o Directional deposition of carbon or a metallic film on a plastic replica so as to highlight features

to be analyzed by transmission electron microscopy Most often used to provide maximum detail and resolution of the features of fracture surfaces

o shank-type cutter

o A cutter having a straight or tapered shank to fit into a machine-tool spindle or adapter

o shape memory alloys

o A group of metallic materials that demonstrate the ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure

o shaping

o Producing flat surfaces using single-point tools The work is held in a vise or fixture or is clamped directly to the table The ram supporting the tool is reciprocated in a linear motion past the work

o shear

o (1) The type of force that causes or tends to cause two contiguous parts of the same body to slide relative to each other in a direction parallel to their plane of contact (2) A machine or tool for cutting metal and other material by the closing motion of two sharp, closely adjoining edges; for example, squaring shear and circular shear (3) An inclination between two cutting edges, such as between two straight knife blades or between the punch cutting edge and the die cutting edge, so that a reduced area will be cut each time This lessens the necessary force, but increases the

required length of the working stroke This method is referred to as angular shear (4) The act of cutting by shearing dies or blades, as in shearing lines

o shear modulus (G)

o The ratio of shear stress to the corresponding shear strain for shear stresses below the proportional limit of the material Values of shear modulus are usually determined by torsion testing Also known as modulus of rigidity

o shear plane

o A confined zone along which shear takes place in metal cutting It extends from the cutting edge

to the work surface

o shear strain

o The tangent of the angular change, caused by a force between two lines originally perpendicular

to each other through a point in a body Also called angular strain

o sheet forming

o The plastic deformation of a piece of sheet metal by tensile loads into a three-dimensional shape, often without significant changes in sheet thickness or surface characteristics Compare with bulk forming

piece and surrounds a core of essentially pearlitic transformation product This result is accomplished by a proper balance among section size, steel hardenability, and severity of quench

o shelling

o (1) A term used in railway engineering to describe an advanced phase of spalling (2) A mechanism of deterioration of coated abrasive products in which entire abrasive grains are removed from the coating that holds the abrasive to the backing layer of the product

o shell molding

o A foundry process in which a mold is formed from thermosetting resin-bonded sand mixtures brought in contact with preheated (150 to 260 °C, or 300 to 500 °F) metal patterns, resulting in a firm shell with a cavity corresponding to the outline of the pattern Also called Croning process

o shielded metal arc cutting

o A metal arc cutting process in which metals are severed by melting them with the heat of an arc between a covered metal electrode and the base metal

o shielded metal arc welding (SMAW)

o An arc welding process that produces coalescence of metals by heating them with an arc between

a covered metal electrode and the workpieces Shielding is obtained from decomposition of the electrode covering Pressure is not used, and filler metal is obtained from the electrode Also commonly referred to as stick welding

o shielding gas

o (1) Protective gas used to prevent atmospheric contamination during welding (2) A stream of inert gas directed at the substrate during thermal spraying so as to envelop the plasma flame and substrate; intended to provide a barrier to the atmosphere in order to minimize oxidation

o Shore hardness test

o Same as Scleroscope hardness test

o short-circuiting transfer

o In consumable electrode arc welding, a type of metal transfer similar to globular transfer, but in which the drops are so large that the arc is short circuited momentarily during the transfer of each drop to the weld pool Compare with globular transfer and spray transfer

o shotting

o The production of shot by pouring molten metal in finely divided streams Solidified spherical particles are formed during descent in a tank of water

o shrinkage

o (1) The contraction of metal during cooling after hot forging Die impressions are made oversize according to precise shrinkage scales to allow the forgings to shrink to design dimensions and tolerances (2) See casting shrinkage

o A protective, refractory-lined metal-delivery system to prevent reoxidation of molten steel when

it is poured from ladle to tundish to mold during continuous casting

o shut height

o For a metalforming press, the distance from the top of the bed to the bottom of the slide with the stroke down and adjustment up In general, it is the maximum die height that can be accommodated for normal operation, taking the bolster plate into consideration See also bolster

o That portion of a powder sample that passes through a sieve of specified number and is retained

by some finer mesh sieve of specified number See also sieve analysis

o sigma phase

o A hard, brittle, nonmagnetic intermediate phase with a tetragonal crystal structure, containing 30

atoms per unit cell, space group, P4/mnm, occurring in many binary and ternary alloys of the

transition elements The composition of this phase in the various systems is not the same, and the phase usually exhibits a wide range in homogeneity Alloying with a third transition element usually enlarges the field homogeneity and extends it deep into the ternary section

o sigma-phase embrittlement

o Embrittlement of iron-chromium alloys (most notably austenitic stainless steels) caused by precipitation at grain boundaries of the hard, brittle intermetallic phase during long periods of exposure to temperatures between approximately 560 and 980 °C (1050 and 1800 °F) Sigma-phase embrittlement results in severe loss in toughness and ductility and can make the embrittled material susceptible to intergranular corrosion See also sensitization

o siliconizing

o Diffusing silicon into solid metal, usually low-carbon steels, at an elevated temperature in order

to improve corrosion or wear resistance

o silky fracture

o A metal fracture in which the broken metal surface has a fine texture, usually dull in appearance Characteristic of tough and strong metals Contrast with crystalline fracture and granular fracture

o silver soldering

o Nonpreferred term used to denote brazing with a silver-base filler metal See preferred terms furnace brazing , induction brazing , and torch brazing

o single-action press

o A metalforming press that provides pressure from one side

o single impulse welding

o A resistance welding process variation in which spot, projection, or upset welds are made with a single impulse

o single welded joint

o In arc and gas welding, any joint welded from one side only

o size effect

o Effect of the dimensions of a piece of metal on its mechanical and other properties and on manufacturing variables such as forging reduction and heat treatment In general, the mechanical properties are lower for a larger size

o sizing

o (1) Secondary forming or squeezing operations needed to square up, set down, flatten, or otherwise correct surfaces to produce specified dimensions and tolerances See also restriking (2) Some burnishing, broaching, drawing, and shaving operations are also called sizing (3) A finishing operation for correcting ovality in tubing (4) Final pressing of a sintered powder metallurgy part to obtain a desired dimension

o (1) Removal of a material in thin layers or chips with a high degree of shear or slippage, or both,

of the cutting tool (2) A machining operation in which the cut is made with a form tool with its face so angled that the cutting edge progresses from one end of the work to the other as the tool feeds tangentially past the rotating workpiece

o slag

o A nonmetallic product resulting from the mutual dissolution of flux and nonmetallic impurities in smelting, refining, and certain welding operations (see, for example, electroslag welding ) In steelmaking operations, the slag serves to protect the molten metal from the air and to extract certain impurities

is often called the platen

o slip band

o A group of parallel slip lines so closely spaced as to appear as a single line when observed under

an optical microscope See also slip line

o slip line

o Visible traces of slip planes on metal surfaces; the traces are (usually) observable only if the surface has been polished before deformation The usual observation on metal crystals (under a light microscope) is of a cluster of slip lines known as a slip band

o An imperfection consisting of a very thin elongated piece of metal attached by only one end to the parent metal into whose surface it has been worked

o slow strain rate technique

o An experimental technique for evaluating susceptibility to stress-corrosion cracking It involves pulling the specimen to failure in uniaxial tension at a controlled slow strain rate while the specimen is in the test environment and examining the specimen for evidence of stress-corrosion cracking

o S-N curve

o A plot of stress (S) against the number of cycles to failure (N) The stress can be the maximum stress (Smax) or the alternating stress amplitude (Sa) The stress values are usually nominal stress;

i.e., there is no adjustment for stress concentration The diagram indicates the S-N relationship for

a specified value of the mean stress (Sm) or the stress ratio (A or R) and a specified probability of survival For N a log scale is almost always used For S a linear scale is used most often, but a log scale is sometimes used Also known as S-N diagram

o soak cleaning

o Immersion cleaning without electrolysis

o soaking

o In heat treating of metals, prolonged holding at a selected temperature to effect homogenization

of structure or composition See also homogenizing

o soft magnetic material

o A ferromagnetic alloy that becomes magnetized readily upon application of a field and that returns to practically a nonmagnetic condition when the field is removed; an alloy with the properties of high magnetic permeability, low coercive force, and low magnetic hysteresis loss

o A group of processes that join metals by heating them to a suitable temperature below the solidus

of the base metals and applying a filler metal having a liquidus not exceeding 450 °C (840 °F) Molten filler metal is distributed between the closely fitted surfaces of the joint by capillary action See also solder

o solidification shrinkage crack

o A crack that forms, usually at elevated temperature, because of the internal (shrinkage) stresses that develop during solidification of a metal casting Also termed hot crack

o solid lubricant

o Any solid used as a powder or thin film on a surface to provide protection from damage during relative movement and to reduce friction and wear

o solid metal embrittlement

o The occurrence of embrittlement in a material below the melting point of the embrittling species See also liquid metal embrittlement

o solidus

o (1) The highest temperature at which a metal or alloy is completely solid (2) In a phase diagram, the locus of points representing the temperatures at which various compositions stop freezing upon cooling or begin to melt upon heating See also liquidus

o solute

o The component of either a liquid or solid solution that is present to a lesser or minor extent; the component that is dissolved in the solvent

o solution heat treatment

o Heating an alloy to a suitable temperature, holding at that temperature long enough to cause one

or more constituents to enter into solid solution, and then cooling rapidly enough to hold these constituents in solution

o sorbite (obsolete)

o A fine mixture of ferrite and cementite produced either by regulating the rate of cooling of steel

or by tempering steel after hardening The first type is very fine pearlite that is difficult to resolve under the microscope; the second type is tempered martensite

o sour gas

o A gaseous environment containing hydrogen sulfide and carbon dioxide in hydrocarbon reservoirs Prolonged exposure to sour gas can lead to hydrogen damage, sulfide-stress cracking, and/or stress-corrosion cracking in ferrous alloys

o sow block

o A block of heat-treated steel placed between the anvil of the hammer and the forging die to prevent undue wear to the anvil Sow blocks are occasionally used to hold insert dies Also called anvil cap

o space lattice

o A regular, periodic array of points (lattice points) in space that represents the locations of atoms

of the same kind in a perfect crystal The concept may be extended, where appropriate, to crystalline compounds and other substances, in which case the lattice points often represent locations of groups of atoms of identical composition, arrangement, and orientation

o spangle

o The characteristic crystalline form in which a hot dipped zinc coating solidifies on steel strip

o spark testing

o A method used for the classification of ferrous alloys according to their chemical compositions,

by visual examination of the spark pattern or stream that is thrown off when the alloys are held against a grinding wheel rotating at high speed

o In welding, the speed with which a weld is made along its longitudinal axis, usually measured in meters per second or inches per minute

at a temperature just below Ae1 (4) Cooling at a suitable rate from the minimum temperature at which all carbide is dissolved to prevent the reformation of a carbide network, and then reheating

in accordance with method 1 or 2 above (Applicable to hypereutectoid steel containing a carbide network.)

o spiegeleisen (spiegel)

o A pig iron containing 15 to 30% Mn and 4.5 to 6.5% C

o spindle

o (1) Shaft of a machine tool on which a cutter or grinding wheel may be mounted (2) Metal shaft

to which a mounted wheel is cemented

o spinning

o The forming of a seamless hollow metal part by forcing a rotating blank to conform to a shaped mandrel that rotates concentrically with the blank In the typical application, a flat-rolled metal blank is forced against the mandrel by a blunt, rounded tool; however, other stock (notably, welded or seamless tubing) can be formed A roller is sometimes used as the working end of the tool

o spinodal structure

o A fine, homogeneous mixture of two phases that form by the growth of composition waves in a solid solution during suitable heat treatment The phases of a spinodal structure differ in composition from each other and from the parent phase, but have the same crystal structure as the parent phase

o sponge

o A form of metal characterized by a porous condition that is the result of the decomposition or reduction of a compound without fusion The term is applied to forms of iron, titanium, zirconium, uranium, plutonium, and the platinum-group metals

o sponge iron

o A coherent, porous mass of substantially pure iron produced by solid-state reduction of iron oxide (mill scale or iron ore)

o spot drilling

o Making an initial indentation in a work surface, with a drill, to serve as a centering guide in a subsequent machining process

o spotfacing

o Using a rotary, hole-piloted end-facing tool to produce a flat surface normal to the axis of rotation

of the tool on or slightly below the workpiece surface

o spot weld

o A weld made between or upon overlapping members in which coalescence may start and occur on the faying surfaces or may proceed from the surface of one member The weld cross section is approximately circular

o spray transfer

o In consumable-electrode arc welding, a type of metal transfer in which the molten filler metal is propelled across the arc as fine droplets Compare with globular transfer and short-circuiting transfer

o springback

o (1) The elastic recovery of metal after stressing (2) The extent to which metal tends to return to its original shape or contour after undergoing a forming operation This is compensated for by overbending or by a secondary operation of restriking (3) In flash, upset, or pressure welding, the deflection in the welding machine caused by the upset pressure

o square drilling

o Making square holes by means of a specially constructed drill made to rotate and also to oscillate

so as to follow accurately the periphery of a square guide bushing or template

o squaring shear

o A machining tool, used for cutting sheet metal or plate, consisting essentially of a fixed cutting knife (usually mounted on the rear of the bed) and another cutting knife mounted on the front of a reciprocally moving crosshead, which is guided vertically in side housings Corner angles are usually 90°

so that sensitization is avoided on subsequent exposure to elevated temperature

o stack cutting

o Thermal cutting of stacked metal plates arranged so that all the plates are severed by a single cut

o stack molding

o A foundry practice that makes use of both faces of a mold section, one face acting as the drag and the other as the cope Sections, when assembled to other similar sections, form several tiers of mold cavities, all castings being poured together through a common sprue

o The general term used to denote all sheet metal pressworking It includes blanking, shearing, hot

or cold forming, drawing, bending, or coining

o stand

o A piece of rolling mill equipment containing one set of work rolls In the usual sense, any pass of

a cold- or hot-rolling mill See also rolling mills

o standard electrode potential

o The reversible potential for an electrode process when all products and reactions are at unit activity on a scale in which the potential for the standard hydrogen half-cell is zero

o standard gold

o A gold alloy containing 10% Cu; at one time used for legal coinage in the United States

o standard reference material

o A reference material, the composition or properties of which are certified by a recognized standardizing agency or group

o steadite

o A hard structural constituent of cast iron that consists of a binary eutectic of ferrite, containing some phosphorus in solution, and iron phosphide (Fe3P) The eutectic consists of 10.2% P and 89.8% Fe The melting temperature is 1050 °C (1920 °F)

o Stead's brittleness

o A condition of brittleness that causes transcrystalline fracture in the coarse grain structure that results from prolonged annealing of thin sheets of low-carbon steel previously rolled at a temperature below about 705 °C (1300 °F) The fracture usually occurs at about 45° to the direction of rolling

o steam hammer

o A type of drop hammer in which the ram is raised for each stroke by a double-action steam cylinder and the energy delivered to the workpiece is supplied by the velocity and weight of the ram and attached upper die driven downward by steam pressure The energy delivered during each stroke can be varied

o steam treatment

o The treatment of a sintered ferrous part in steam at temperatures between 510 and 595 °C (950 to

1100 °F) in order to produce a layer of black iron oxide (magnetite, or ferrous-ferric oxide, FeO·Fe2O3) on the exposed surface for the purpose of increasing hardness and wear resistance

o Steckel mill

o A cold reducing mill having two working rolls and two backup rolls, none of which is driven The strip is drawn through the mill by a power reel in one direction as far as the strip will allow and then reversed by a second power reel, and so on until the desired thickness is attained

o steel

o An iron-base alloy, malleable in some temperature ranges as initially cast, containing manganese, usually carbon, and often other alloying elements In carbon steel and low-alloy steel, the maximum carbon is about 2.0%; in high-alloy steel, about 2.5% The dividing line between low-alloy and high-alloy steels is generally regarded as being at about 5% metallic alloying elements

Steel is said to be differentiated from two general classes of "irons": the cast irons, on the carbon side and the relatively pure irons such as ingot iron, carbonyl iron, and electrolytic iron,

high-on the low-carbhigh-on side In some steels chigh-ontaining extremely low carbhigh-on, the manganese chigh-ontent

is the principal differentiating factor, steel usually containing at least 0.25% and ingot iron considerably less

o strain-age embrittlement

o A loss in ductility accompanied by an increase in hardness and strength that occurs when carbon steel (especially rimmed or capped steel) is aged following plastic deformation The degree of embrittlement is a function of aging time and temperature, occurring in a matter of minutes at about 200 °C (400 °F), but requiring a few hours to a year at room temperature

low-o strain aging

o (1) Aging following plastic deformation (2) The changes in ductility, hardness, yield point, and tensile strength that occur when a metal or alloy that has been cold worked is stored for some time In steel, strain aging is characterized by a loss of ductility and a corresponding increase in hardness, yield point, and tensile strength

o strain energy

o The potential energy stored in a body by virtue of elastic deformation, equal to the work that must

be done to produce this deformation

value," is equal to the slope of the true stress/true strain curve up to maximum load, when plotted

on log-log coordinates The n-value relates to the ability of as sheet metal to be stretched in metalworking operations The higher the n-value, the better the formability (stretchability)

o strain rate

o The time rate of straining for the usual tensile test Strain as measured directly on the specimen gage length is used for determining strain rate Because strain is dimensionless, the units of strain rate are reciprocal time

o strain-rate sensitivity (m-value)

o The increase in stress ( ) needed to cause a certain increase in plastic strain rate ( ) at a given

level of plastic strain ( ) and a given temperature (T):

o strain rods