Glossary of Steel Terms

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SAE
Abbreviation for Society of Automotive Engineers. This organization has specified common and alloy steels and copper base alloys in accordance with a numerical index system allowing approximation of the composition of the metal. The last two digits always indicate the carbon content, usually within 0.05%.

Salt Spray Test
An accelerated corrosion test in which the metal specimens are exposed to a fine mist of salt water solution either continuously or intermittently.

Scab
A defect consisting of a flat volume of metal joined to a casting through a small area. It is usually set in a depression, a flat side being separated from the metal of the casting proper by a thin layer of sand.

Scab (scabby)
A blemish caused on a casting by eruption of gas from the mold face, or by uneven mold surfaces; or occurring where the skin from a blowhole has partly burned away and is not welded.

Scale
A layer of oxidation products formed on a metal at high temperature.

Scaling
(1) Oxidation of metal due to heat, resulting in relatively heavy surface layers of oxide. (2) Removal of scale from metal.

Scaling
Forming a thick layer of oxidation products on metals at high temperatures.

Scalped Extrusion Ingot
A cast, solid, or hollow extrusion ingot which has been machined on the outside surface.

Scalping
Machining the surface layers from ingots, billets and slabs before fabrication.

Scarf Joint
A butt joint in which the plane of the joint is inclined with respect to the main axes of the members.

Scarfing
Cutting surface areas of metal objects, ordinarily by using a gas torch. The operation permits surface defects to be cut from ingots, billets, or the edges of plate that is to be beveled for butt welding.

Scarfing
Cutting surface areas of metal objects, ordinarily by using a gas torch. The operation permits surface defects to be cut from ingots, billets, or the edges of plate that is to be beveled for butt welding.

Scleroscope Hardness (Test)
A method for measuring the hardness of metals; a diamond-pointed hammer drops from a fixed distance through a tube onto the smoothed metal surface and the rebound measured. The scleroscope hardness value is empirically taken from the rebound distance, with a specified high-carbon steel as 100.

Scleroscope Test
A hardness test where the loss in kinetic energy of a falling metal tup, absorbed by indentation upon impact of the tup on the metal being tested, is indicated by the height of rebound.

Scrap
Material unsuitable for direct use but usable for reprocessing by re-melting.

Scratch Brushed Finish
Finish obtained by mechanically brushing the surface with wire bristle brushes, by buffing with greaseless compound or by cold rolling with wire bristled rolls on scratch etched finish.

Seam
On the surface of metal, an unwelded ford or lap which appears as a crack, usually resulting from a defect obtained in casting or in working.

Seam (A defect.)
On the surface of metal a crack that has been closed but not welded; usually produced by some defect either in casting or in working, such as blowholes that have become oxidized or folds and laps that have been formed during working. Similar to cold shut and laminations.

Seam Welding
An electric-resistance type of welding process, in which the lapped sheet is passed between electrodes of the roller type while a series of overlapping spot welds is made by the intermittent application of electric current.

Secondary Hardening
Tempering certain alloy steels at certain temperatures so that the resulting hardness is greater than that obtained by tempering the same steel at some lower temperature for the same time.

Seconds
The designation given to sheet or strip that has imperfections in moderate degree or extent, which may be classified in two general groups -- imperfections in the base material, or other manufacturing defects. This term not used in connection with non-ferrous alloys.

Segment Steel
Used for laminated piston rings. Carbon content about .60%. Hardened and blue tempered with round edges. Hardness usually Rockwells 30 N 68 to 71, widths vary from .058 to .163 and thicknesses are .020, .024 and .030.

Segregation
Nonuniform distribution of alloying elements, impurities or phases.

Segregation
Nonumiform distribution of alloying elements, impurities or microphases.

Segregation
In an alloy, concentration of alloying elements at specific regions, usually as a result of the primary crystallization of one phase with the subsequent concentration of other elements in the remaining liquid.

Segregation Banding
In homogeneous distribution of alloying elements aligned on filaments or plates parallel to the direction of working.

Self Diffusion
The spontaneous movement of an atom to a new site in a crystal of its own species.

Self-Hardening Steel
A steel containing sufficient carbon or alloying element, or both, fo form martensite either through air hardening or, as in welding and induction hardening, through rapid removal of heat from a locally heated portion by conduction into the surrounding cold metal.

Semi-Steel
Cast iron (not steel) of high quality, obtained by using a large percentage of steel scrap with the pig iron.

Semifinished Steel
Steel in the form of billets, blooms, itc., requiring further working before completion into finished steel ready for marketing.

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

Semikilled Steel
Steel that is completely deoxided and contains sufficient dissolved oxygen to react with the carbon to form carbon monoxide to offset solidifacation shrinkage.

Semikilled Steel
Steel incompletely deoxidized, to permit evolution of sufficient carbon monoxide to offset solidification shrinkage.

Sendzimir Mill
A mill having two work rolls of 1 to 2 1/2-in diam. each, backed up by two rolls twice that diameter and each of these backed up by bearings on a shaft mounted eccentrically so that rotating it increases the pressure between bearings and backup rolls.

Shear
A type of cutting operation in which the metal object is cut by means of a moving blade and fixed edge or by a pair of moving blades that may be either flat or curved.

Shear
That 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.

Shear Bands (deformation)
Bands in which deformation has been concentrated inhomogeneously in sheets that extend across regional groups of grains. Usually only one system is present in each regional group of grains, different systems being present in adhoining groups. The bands are noncrystallographic and form on planes of maximum shear stress (55(degrees) to the compression direction). They carry most of the deformation at large strains. Compare microbands.

Shear Crack
A diagonal, transgranular crack caused by shear stresses.

Shear Steel
Steel produced by forge welding together several bars of blister steel, providing a more homogeneous product.

Shear Strength
The stress required to produce fracture in the plane of cross section, the conditions of loading being such that the directions of force and of resistance are parallel and opposite although their paths are offset a specified minimum amount.

Sheet
A flat-rolled metal product of some maximum thickness and minimum width arbitrarily dependent on the type of metal. Sheet is thinner than plate.

Shell Molding
Forming a mold from thermosetting resin-bonded sand mixtures brought in contact with pregeated (300 to 500 (degrees) F) metal patterns, resulting in a firm shell with a cavity corresponding to the outline of the pattern. Also called Croning process.

Shielded-Arc Welding
Arc welding in which the arc and the weld metal are protected by a gaseous atmosphere, the products of decomposition of the electrode covering, or a blanket of fusible flux.

Shim
A thin flat hard metal strip produced to close tolerances; used primarily for tool, die and machine alignment purposes. In steel there are four general types: (1) Low Carbon Rockwell B 80/100; (2) Hard Rolled High Carbon Rockwell C 28/33. (3) Hardened and Tempered Spring Steel Rockwell C 44/51; (4) Austenitic Stainless Steel Rockwell C 35/45. Brass shim of commercial quality is also used and most generally specified is 2 Nos. Hard but may be 4 Nos. Hard.

Shore Hardness Test
Same as scleroscope test.

Short
Brittle.

Short Terne
A term applying to terne coated (Lead and Tin) sheets with reference to Base Box sizes (14 x 20) Refer to terne plate.

Shortness
A form of brittleness in metal. It is designed as cold, hot, and red, to indicate the temperature range in which the brittleness occurs.

Shortness
A form of brittleness in metal. It is designated as cold, hot, and red, to indicate the temperature range in which the brittleness occurs.

Shot Blasting
Cleaning surface of metal by air blast, using metal as a result of solidification shrinkage and the progressive freezing of metal towards the center.

Shrinkage Cavity
A void left in cast metals as a result of solidification shrinkage and the progressive freezing of metal towards the center.

Silicon
Chemical symbol Si. Element No. 14 of the periodic system; atomic weight 28.06. Extremely common element, the major component of all rodks and sands; its chemical reactions, however, are those of a metalloid. Used in metallurgy as a deoxidizing scavenger. Silicon is present, to some extent, in all steels, and is deliberately added to the extent of approximately 4% for electric sheets, extensively used in alternating current magnetic circuits. Silicon cannot be electrodeposited.

Silicon Steel
Steel usually made in the basic open-hearth or electric furnace, with about 0.50-5.% silicon, other elements being usually dept as low as possible. Because of high electrical resistance and low hysterisis loss, silicon sheet and strip are standard in electric magnet manufacture.

Siliconizing
Diffusing silicon into solid metal, usually steel, at an elevated temperature.

Silky Fracture
A steel fracture that has a very smooth fine grain or silky appearance.

Silver Solders
Alloys of silver, copper, sinc and other metals, melting between 650 and 875 (degrees) C. used for making strong yet moderately ductile joints that resist corrosion.

Single-Action Press
A forming press that operates with a single function, such as moving a punch into a die with no simultaneous action for holding down the bland or ejecting the formed work.

Sinker Steel
Used for making sinkers in hosiery making machinery. Supplied both hardened and tempered and cold rolled and annealed. Usually extra precision rolled and extra flat. Carbon content about 1.25.

Sinkhead or Hot Top
A reservoir insulated to retain heat and to hod excess molten metal on top of an ingot mold, in order to feed the shrinkage of the ingot. Also called shrink head or feeder head.

Sintered Carbide
Composite, containing carbides of extremely refractory metals, such as tungsten, tantalum, titanium, etc., cemented together by a relatively low-melting metal, such as cobalt acing as a matrix.

Sintering
Bonding of adjacent surfaces of particles in a mass of metal powders, or in a compact, by heating

Sintering
Converting powder into a continuous mass by heating to a temperature considerably below fusion, usually after preliminary compacting by pressure.

Skelp
A piece or strip of metal produced to a suitable thickness, width, and edge configuration, from which pipe or tubing is made.

Skelp
A plate of steel or wrought iron from which pipe or tubing is made by rolling the skelp into shape longitudinally and welding or riveting the edges together.

Skin
A thin surface layer that is different from the main mass of a metal object, in composition, structure or other characteristics.

Skull
A layer of solidified metal or dross on the wall of a pouring vessel often when metal has been poured.

Slab
A piece of metal, intermediate between ingot and plate, at least twice as wide as it is thick.

Slack Quenching
The process of hardening steel by quenching from the austenitizing temperature at a rate slower than the critical cooling rate for the particular steel, resulting in incomplete hardening and the formation of one or more transformation products in addition to or instead of martensite.

Slag
A product resulting from the action of a flux on the nonmetallic constituents of a processed ore, or on the oxidized metallic constituents that are undesirable. Usually slags consist of combinations of acid oxides with basic oxides, and neutral oxides are added to aid fusibility.

Slag
A nonmetallic product resulting form mutual dissolution of flux and nonmetallic impurities in smelting and refining operations.

Slip
Plastic deformation by irreversible shear displacement of one part of a crystal relative to another in a definite crystallographic direction and on a definite crystallographic plane.

Slip Direction
The crystallographic direction in which translation of slip takes place.

Slip Line
Trace of a slip plane on a viewing surface.

Slip Plane
The crystallographic plane on which slip occurs in a crystal.

Slit Edges
The edges of sheet or strip metal resulting from cutting to width by rotary slitters.

Slitting
Cutting sheet or strip metal to width by rotary slitters.

Sliver (defect)
Loose metal piece rolled down onto the surface of the metal during the rolling operations.

Soaking
Prolonged heating of a metal at selected temperature.

Soft Skin Rolled Temper (No. 4 Temper)
In low carbon-rolled strip steel, soft and ductile. Produced by subjecting annealed strip to a pinch pass or skin rolling (a very light rolling).

Solder Embrittlement
Reduction in ductility of a metal or alloy, associated with local penetration by molten solder along grain boundaries.

Soldering
Joining metals by fusion of alloys that have relatively low melting points -- most commonly, lead-base or tin-base alloys, which are the soft solders. Hard solders are alloys that have silver, copper, or nickel bases and use of these alloys with melting points higher than 800 (degrees) F. is generally termed brazing.

Solid Solution
A single solid homogeneous crystalline phase containing two or more chemical species.

Solid Solution
A solid crystalline phase containing two or more chemical species in concentrations that may vary between limits imposed by phase equilibrium.

Solidus
In a constitutional diagram, the locus of points representing the temperatures at which various components finish freezing on cooling or begin to melt on heating.

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

Solution Heat Treatment
A heat treatment in which an alloy is heated to a suitable temperature, held at that temperature long enough to cause one or more constituents to enter into solid solution, and then cooled rapidly enough to hold these constituents in solution.

Solution Heat Treatment
Heating an alloy to a suitable temperature, holding at that temperature long enough to allow one or more constituents to enter into solid solution, and then cooling rapidly enough to hold the constituents in solution. The alloy is left in a supersaturated, unstable state, and may subsequently exhibit quench aging.

Solution Heat Treatment
A process in which an alloy is heated to a suitable temperature long enough to allow a certain constituent to enter into solid solution and is then cooled rapidly to hold the constituent in solution. The metal is left in a supersaturated, unstable state and may subsequently exhibit age hardening.

Solvent
The component of either a liquid or solid solution that is present to the greater or major extent; the component that dissolves the solute.

Solvus
In a phase or equilibrium diagram, the locus of points representing the temperature at which solid phases with various compositions coexist with other solid phases; that is, the limits of solid solubility.

Sorbite
Structure of steel, resulting from the tempering of martensite. In a truly sorbitic structure, the cementite is completely dispersed in the matrix. The trend is to call this structure tempered martensite.

Sorbite (obsolete)
A fine mixture of ferrite and cementite produced either by regulating the rate of cooling of steel or tempering steel after hardening. The first type is very fine pearlite difficult to resolve under the microscope; the second type is tempered martensite.

Sorbitic Pearlite
Structure of steel resulting, on cooling under the proper conditions, from the decomposition of austenite; has a fine, lamellar appearance.

Space Lattice (crystal)
A system of equivalent points formed by the intersections of three sets of planes parallel to pairs of principal axes; the space lattice may be thought of as formed by the corners of the unit cells.

Space-Centered (concerning space lattices)
Body-centered.

Spalling
The cracking and flaking of particles out of a surface.

Specific Gravity
A numerical value representing the weight of a given substance as compared with the weight of an equal volume of water, for which the specific gravity is taken as 1.0000.

Spectograph
An optical instrument for determining the presence or concentration of minor metallic constituents in a material by indicating the presence and intensity of specific wave lengths of radiation when the material is thermally or electrically excited.

Spectograph (X-rays)
An instrument using an extended surface -- a photographic plate or film, or a fluorescent screen -- for receiving the X-ray diffraction pattern.

Spelter (Prime Western Spelter)
A low-grade of Virgin Zinc containing approximately 98% Zinc used in Galvanizing processes.

Speroidizing
Heating and cooling to produce a spheroidal or globular form of carbide in steel. Spheroidizing methods frequently used are: 1. Prolonged holding at a temperature just below Ae1. . 2. Heating and cooling alternately between temperatures that are just below Ae1. . 3. Heating to temperature above Ae1 or Ae3 and then cooling very slowly in the furnace or holding 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 re-heating in accordance with methods 1 or 2 above. (Applicable to hypereutectoid steel containing a carbide network.

Speroidizing Annealing
A subcritical annealing treatment intended to produce spheroidization of cementite or other carbide phases.

Spheroidized Structure
A microstructure consisting of a matrix containing spheroidal particles of another constituent.

Spheroidizing
Any process of prolonged heating and slow cooling of steel which will convey the carbide content into rounded or spheroid form.

Spheroidizing
Heating and cooling to produce a spheroidal or globular form of carbide in steel.

Spiegel
High-manganese pig iron, containing 15-30% manganese, approximately 5% carbon, and less than 1% silicon used in the manufacture of steel by the Bessemer, or basic open-hearth process.

Spinning
The procedure of making sheet metal discs into hollow shapes by pressing the metal against a rotating form (spinning chuck) by a tool.

Spot Welding
An electric-resistance welding process in which the fusion is limited to a small area. The pieces being welded are pressed together between a pair of water-cooled electrodes through which an electical current is passed during a very short interval so that fusion occurs over a small area at the interface between the pieces.

Spot Welding
Welding of lapped parts in which fusion is confined to a relatively small circular area. It is generally resistance welding, but may also be gas-shielded tungsten-arc, gas-shielded metal-arc, or submerged-arc welding.

Spring Steel Strip
Any of a number of strip steels produced for use in the manufacture of steel springs or where high tensile properties are required marketed in the annealed state, hard rolled or as hardened and tempered strip.

Spring Temper
In brass mill terminology, Spring Temper is eight numbers hard or 60.50% reduction.

Spring-Back
An indicator of elastic stresses, frequently measured as the increase in diameter of a curved strip after removing it from the mandrel about which it was held. The measurement is employed as an indicator of the extent of recovery or relief of residual stresses that has been achieved by the transformation of elastic strain to plastic strain during heating or stress relieving.

Stabilizing Anneal
A treatment applied to austentic stainless steels that contain titanium or columbium. This treatment consists of heating to a temperature below that of a full anneal in order to precipitate the maximum amount of carbon at titanium carbide or columbium carbide. This eliminates precipitation at lower temperatures, which might reduce the resistance of the steel to corrosion.

Stabilizing Treatment
A thermal treatment designed to precipitate material from solid solution, in order to improve the workability, to decrease the tendency of certain alloys to age harden at room temperature, or to obtain dimensional stability under service at slightly elevated temperatures.

Stablizing Treatment
Any treatment intended to stabilize the structure of an alloy of the dimensions of a part. (1) Heating austenitic stainless steels that contain titanium, columbium, or tantalum to a suitable temperature below that of a full anneal in order to inactivate the maximum amount of carbon by precipitation as a carbide of titanium, columbium, or tantalum. (2) Transforming retained austenite in parts made from tool steel. (3) Precipitating a constituent from a nonferrous solid solution to improve the workability, to decrease the tendency of certain alloys to age harden at room temperature, or to obtain dimensional stability.

Stainless Steel
Corrosion resistant steel of a wide variety, but always containing a high percentage of chromium. These are highly resistant to corrosion attack by organic acids, weak mineral acids, atmospheric oxidation, etc.

Stamping
A term used to refer to various press forming operations in coining, embossing, blanking, and pressing.

Standard Gold
A legally adopted alloy for coinage of gold. In the United States the alloy contains 10% Cu.

Steel
An iron-base alloy usually containing carbon and other alloying elements. In carbon steel and low-alloy steel, the maximum carbon content 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 the 5% level of total metallic alloying elements. Steel is differentiated from two general classes of iron - namely, cast irons, which have high carbon concentrations, and relatively pure irons, which have low carbon concentrations.

Steel
An iron-base alloy, malleable in some temperature range as initially cast, containing maganease, 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 to be differentiated from two general classes of irons: the cast irons, on the high-carbon side, and the relatively pure irons such as ingot iron, carbonyl iron, and electrolytic iron, on the low-carbon side. In some steels containing extremely low carbon, the maganese content is the principal differentiating factor, steel usually containing at least 0.25%; ingot iron contains considerably less.

Steel
Iron, malleable in at least one range of temperature below its melting point without special heat treatment, substantially free from slag, and containing carbon bore than about 0.05% and less than about 2.00%. Other alloying elements may be present in significant quantities, but all steels contain at least small amounts of manganese and silicon, and usually as undesirable constituents.

Sterling Silver
A silver alloy containing at least 95.2% Ag, the remainder being unspecified but usually copper.

Sticker
Steel sheets or strip adhering. Usually by fusion spots caused by overheating during box annealing.

Straight-Chrome
An iron alloy. A term indicating a group of stainless steels the principal alloying element of which is chromium in varying amounts from 4.00 to 27.00%.

Strain
A measure of the relative change in the size of a body. Linear strain is the change per unit length of a linear dimension. True (or natural) strain is the natural logarithm of the ratio of the length at the moment of observation to the original gauge length. Shearing strain is the change in angle (expressed in radians) between two reference lines originally at right angles. When the term is used alone, it usually refers to linear strain in the direction of the applied stress.

Strain
A measure of the change in the size or shape of a body, referred to its original size or shape. Linear strain is the change per unit length of a linear dimension. True strain (or natural strain) is the natural logarithm of the ratio of the length at the moment of observation to the original gauge length. Conventional strain is the linear strain referred to the original gauge length. Shearing strain (or shear strain) is the change in angle (expressed in radians) between two lines originally at right angles. When the term strain is used alone it usually refers to the linear strain in the direction of the applied stress.

Strain
Deformation produced on a body by an outside force.

Strain Aging
Aging induced by cold work.

Strain Aging
Aging induced by cold working.

Strain Hardening
An increase in hardness and strength caused by plastic deformation at temperatures lower than the recrystallization range.

Strain Hardening
An increase in hardness and strength caused by p;astic deformation at temperatures below the recrystallization range.

Stress
Force per unit area. True stress denotes stress determined by measuring force and area at the same time. Conventional stress, as applied to tension and compression tests, is force divided by original area. Nominal stress is stress computed by simple elasticity formula.

Stress
Force per unit area, often thought of as force acting through a small area within a plane. It can be divided into components, normal and parallel to the plane, called normal stress and shear stress, receptively. True stress denotes the stress where force and area are measured at the same time. Conventional stress, as applied to tension and compression tests, is force decided by the original gauge length. Shearing strain (or shear strain) is the change in angle (expressed in radians) between two lines originally at right angles. When the term strain is used alone it usually refers to the linear strain in the direction of the applied stress.

Stress
Deforming force to which a body is subjected, or, the resistance which the body offers to deformation by the force.

Stress Relief
Low temperature annealing for removing internal stresses, such as those resulting on a metal from work hardening or quenching.

Stress Relieving
Heating to a suitable temperature, holding long enough to reduce residual stresses and then cooling slowly enough to minimize the development of new residual stresses.

Stress Relieving
Heating to a suitable temperature, holding long enough to reduce residual stresses and then cooling slowly enough to minimize the development of new residual stresses.

Stress-corrosion Cracking
Failure by cracking under the combined action of corrosion and stress, either external (applied) or internal (residual). Cracking may be either intergranular or transgranular, depending on the metal and the corrosive medium.

Stress-Corrosion Cracking
Failure by cracking under combined action or corrosion and stress, either external (applied) or internal (residual). Cracking may be either intergranular or transgranular, depends on metal and corrosive medium.

Stress-Rupture Test
A tension test performed at constant temperature, the load being held at such a level as to cause rupture. Also known as creep-rupture test.

Stretch Forming
A process of forming panels and cowls of large curvature by stretching sheet over a form of the desired shape. This method is more rapid than hammering and beating.

Stretcher Leveling
Leveling where a piece of metal is gripped at each end and subjected to a stress higher than its yield strength to remove warp and distortion. Sometimes called patent leveling.

Stretcher Leveling
A method of making metal sheet or strip dead flat by stretching.

Stretcher Straightening
A process for straightening rod, tubing, and shapes by the application of tension at the ends of the stock. The products are elongated a definite amount to remove warpage.

Stretcher Strains
Elongated markings that appear on the surface of some materials when deformed just past the yield point. These markings lie approximately parallel to the direction of maximum shear stress and are the result of localized yielding Same as Luders lines.

Stretcher Strains
Long vein-like marks appearing on the surface of certain metals, in the direction of the maximum shear stress, when the metal is subjected to deformation beyond the yield point. Also termed Luders Lines. (Not a defect in No. 5 dead soft temper.)

Stretcher Strains
Elongated markings that appear on the surfaces of some materials when they are deformed just past the yield point. These markings lie approximately parallel to the direction of maximum shear stress and are the result of localized yielding.

Strip
A sheet of metal whose length is many times its width.

Strip Steel (cold rolled)
A flat cold rolled steel product (Other than Flat Wire) 23 15/16 and narrower; under .250 in thickness, which has been cold reduced to desired decimal thickness and temper on single stand, single stand reversing, or tandem cold mills in coil form from coiled hot rolled pickled strip steel.

Structure
The arangement of parts; in crystals, expecially, the shape and dimension of the until cell, and the number, kinds and positions of the atoms within it.

Sub-boundary Structure (subgrain structure)
A network of low-angle boundaries (usually with misorientations or less than one degree) within the main grains of a microstructure.

Subcritical Annealing
An annealing treatment in which a steel is heated to a temperature below the A1 temperature and then cooled slowly to room temperature.

Subgrain
A portion of a crystal or grain slightly different in orientation from neighboring portions of the same crystal. Generally, neighboring subgrains are separated by low-angle boundaries.

Substitutional Solid Solution
A solid solution in which the solvent and solute atoms are located randomly at the atom sites in the crystal structure of the solution.

Substrate
The layer of metal underlying a coating, regardless of whether the layer is base metal.

Sulfide Spheroidization
A stage of overheating in which sulfide inclusions are partly or completely spheroidized.

Sulfur
Chemical symbol S) Element No. 16 of the periodic system; atomic weight 32.06. Non-metal occurring in a number of allotropic modifications, the most common being a pale-yellow brittle solid. In steel most commonly encountered as an undesired contaminant. However, it is frequently deliberately added to cutting stock, to increase machinability.

Sulfur Print
A macrographic method of examining distribution of sulfide inclusions.

Superalloy
An alloy developed for very high temperature service where relatively high stresses (tensile, thermal, vibratory, and shock) are encountered and where oxidation resistance is frequently required.

Supercooling
Cooling to a temperature below that of an equilibrium phase transformation without the transformation taking place.

Superficial Rockwell Hardness Test
Form of Rockwell hardness test using relatively light loads which produce minimum penetration. Used for determining surface hardness or hardness of thin sections or small parts, or where large hardness impression might be harmful.

Superheating
(1) Heating a phase to a temperature above that of a phase transformation without the transformation taking place. (2) Heating molten metal to a temperature to obtain more complete refining or greater fluidity.

Surface Hardening
A generic term covering several processes applicable to a suitable ferrous alloy that produce, by quench hardening only, a surface layer that is harder or more wear resistant than the core. There is no significant alteration of the chemical composition of the surface layer. The processes commonly used are induction hardening, flame hardening and shell hardening. Use of the applicable specific process name is preferred.

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