STEEL TERMS GLOSSARY: S - Z
S.A.E. - Abbreviation for Society of Automotive Engineers, an organization that originates many specifications pertaining to steel requirements and testing.
SCARFING - Removal of the surface layer of steel (and the surface defects therein) by using acetylene gas cutting torches. In steelmaking, this is usually done to slabs, blooms, billets or other semifinished steel products.
SCAB - Elongated patches of loosened metal that have been rolled into the steel surface.
SCALE - Oxides of iron that form on the surface of steel at elevated temperature.
SCLEROSCOPE HARDNESS (TEST) - A method for measuring the hardness of metals; a diamond-pointed hammer is dropped from a fixed distance through a tube onto the smoothed metal surface and the rebound is measured. The scleroscope hardness value is empirically taken from the rebound distance, with a specified high-carbon steel as 100.
SEAMS - Open, broken surface running in lines parallel to the rolling direction caused by subsurface inclusions or oxidized ingot/slab cracks.
SEGREGATION - The non-uniformity in chemical composition resulting from natural phenomena in the solidification of a steel ingot. The various elements of the steel have greater solubility in liquid steel than in solid steel, thus, they are concentrated in parts of the ingot last to solidify. Segregation in varying degrees is found in all types of steel.
SEMIFINISHED STEEL - Steel in the form of billets, blooms, etc., requiring further working before completion into finished steel ready for marketing.
SEMIKILLED STEEL - Steel that is partially deoxidized so that there is greater degree of gas evolution than in killed steel, but less than in capped or rimmed steel. The uniformity in composition lies between that of killed steel and rimmed steel.
SILICON - (Chemical Symbol Si) - An extremely common element used as a deoxidizer in steelmaking.
SILICON STEEL - Steel usually made in the electric furnace with about 0.50-5.0% silicon, other elements being usually kept as low as possible. Because of high electrical resistance and low hysteresis loss, silicon sheet and strip are standard in electric magnet manufacture.
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 LAMINATION - Subsurface separation which usually results in surface rupture.
SKIN PASS - A light percentage reduction cold rolling given to steel to obtain final dimensional, physical and/or mechanical properties. Synonymous with TEMPER PASS.
SLAG - A product resulting from the action of a flux on the nonmetallic constituents of a molten metal bath, or on the oxidized metallic constituents that are undesirable.
SLITTING - Cutting steel to width continuously using rotary knives.
SLIVERS - Surface ruptures similar to skin laminations, but usually more pronounced.
SMUT - A reaction product sometimes left on the surface of the sheet after pickling or annealing.
SNAKY EDGES - Carbonaceous deposits in a wavy pattern along the edges of the annealed strip.
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).
SPANGLE - The characteristic crystalline form in which the hot dipped zinc coating solidifies on steel strip.
SPECTROMETRIC CHEMICAL ANALYSIS - Used to determine quantitatively most alloying and residual elements in steel. It is a comparison method based upon a group of steel standards, each having a certified amount of one or more elements. Visible and ultraviolet light, emitted as discrete wavelengths by each element upon excitation by an electrical discharge, is detected in the spectrometer; the signal from each element is converted mathematically into a percent.
SPHEROIDIZING - 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 above and just below Ae1'
3. Heating to a temperature above Ae1 or Ae3 and then cooling very slowly in the furnace or holding at a temperature just below Ae1'
SPINNING - The shaping of flat circular blanks by forcing the blank against a chuck or form block while it is rotating.
SPRINGBACK - The tendency of metal to partially return to its original shape after cold forming.
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; it is marketed in the annealed state, hard rolled or as hardened and tempered strip.
STAMPING - A term used to refer to various press forming operations (blanking, coining, embossing, etc.) or to the product of those operations.
STEEL - Iron with small amounts of carbon added. Although other alloying elements may be present in significant quantities, most steels contain at least small amounts of manganese and, as undesirable residual constituents, sulfur and phosphorus.
STICKER - Adherences of adjacent laps or sheets of steel usually caused by fusion during annealing.
STRAIN - Deformation produced on a body by an outside force.
STRAIN HARDENING - An increase in hardness and strength caused by plastic deformation at temperatures lower than the recrystallization temperature.
STRAIN HARDENING EXPONENT - A measure of the rate of strain hardening. The constant 'n' in the expression rf = KEn where:
rf = True stress
K = Constant in the equation
E = True strain
n = Strain hardening exponent
The 'n' value is a measure of stretch formability. The higher the 'n' value, the better the stretch formability.
STRAIN RATIO - The ratio of width to thickness strain determined in the uniform elongation portion of a tension test. It is a good measure of the crystallographic directionality of the material. It is also a good measure of deep drawability. The higher the' r' value, the better the deep drawability.
STRETCHABILITY - The ability of a metal to be stretched over a punch without splitting.
STRETCH FORMING - Shaping of a sheet or part, usually of uniform cross section, by applying suitable tension or stretch and forming it around or over a die of the desired shape.
STRETCHING - The operation where the blank is stretched around the punch with no metal flow over the draw ring. The metal thickness is reduced.
STRETCHER LEVELING - A method of making metal flat by stretching beyond the yield point either between grippers (sheets) or rolls (coils).
STRETCHER STRAINS (LUDERS LINES) - 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.
STRIP STEEL - Flat steel products less than 24 inches wide and less than .250 inches thick.
SULFUR - (Chemical Symbol S) - Nonmetal occurring most commonly as a pale yellow, brittle solid. Although usually considered an unwanted impurity in steel, it is sometimes added deliberately to enhance machinability.
SURFACE TEXTURE - The finish of the surface of sheet steel presently described by the roughness (peak) height in micro inches and the peaks per inch.
TANDEM MILL - Arrangement of cold rolling mills in a direct line allowing metal to pass from one set of rolls to the next and be in all of the mills simultaneously.
TAPPING - Transfer of molten steel from melting furnace to a ladle.
TELESCOPING - Transverse slipping of successive layers of a coil so that the edge of the coil is irregular rather than flat.
TEMPERING - (Also termed 'drawing') -A process of reheating quench-hardened or normalized steel to a temperature below the transformation range and then cooling at any rate desired. The primary purpose of tempering is to impart a degree of plasticity or toughness to the steel to alleviate the brittleness of martensite.
TEMPER ROLLING - Light cold rolling of sheet steel. This operation is performed to improve flatness, minimize the tendency to stretcher strain and flute, and obtain the desired texture and mechanical properties.
TENSILE STRENGTH - The unit stress at the highest load reached during the tension test.
TENSILE TEST - A test for determining mechanical properties involving placing a standard test specimen in the jaws of a testing machine that records the elongation of the sample for increasing loading up to fracture. Properties determined include YIELD STRENGTH, TENSILE STRENGTH, ELONGATION, and STRAIN HARDENING EXPONENT.
TERNE PLATE - Sheet steel coated with an alloy of lead and less than 10% tin.
TIN - (Chemical Symbol Sn) - Soft silvery white metal of high malleability and ductility but low tensile strength. Used as a coating on steel or as an alloy of coating on steel.
TIN PLATE BASE BOX - A Tin Plate Base Box is measured in terms of pounds per Base Box (112 sheets 14" x 20"), a unit peculiar to the tin industry. This corresponds to an area of sheet totaling 31.360 square inches of any gage and is applied to tin plate weighing from 55 to 275 pounds per base box. To convert to decimal thickness multiply weight per base box by .00011.
TITANIUM - (Chemical Symbol Ti) - Bright white metal used in steelmaking as a carbide former that strengthens steel. Also used to protect BORON from nitrogen degradation in boron bearing heat treatable steels.
TITANIUM STABILIZED, VACUUM DEGASSED STEEL - Another name for INTERSTITIAL FREE STEEL popular in Europe and the far east.
TOUGHNESS - Property of resisting fracture or distortion. Usually measured by IMPACT TEST.
TRANSFORMATION RANGES OR TRANSFORMATION TEMPERATURE RANGES - Those ranges of temperature within which austenite forms during heating and transforms during cooling. The two ranges are distinct, sometimes overlapping but never coinciding. The limiting temperatures of the ranges depend on the composition of the alloy and on the rate of change of temperature, particularly during cooling. See TRANSFORMATION TEMPERATURE.
TRANSFORMATION TEMPERATURE - The temperature at which a change in phase occurs. The term is sometimes used to denote the limiting temperature of a transformation range. The following symbols are used for iron and steels:
ACcm - The temperature at which the solution of cementite in austenite is completed during heating.
AC1 - The temperature at which austenite begins to form during heating.
ACa - The temperature at which transformation of ferrite to austenite is completed during heating.
AC4 - The temperature at which austenite transforms to delta ferrite during heating.
Ae1' Aea. Aecm' Ae4 - The temperatures of phase changes at equilibrium.
Arcm - The temperature at which precipitation of cementite starts during cooling.
Ar1 - The temperature at which transformation of austenite to ferrite or to ferrite plus cementite is completed during cooling.
Ara - The temperature at which austenite begins to transform to ferrite during cooling
Ar4 - The temperature at which delta ferrite transforms to austenite during cooling.
Ms - The temperature at which transformation of austenite to martensite starts during cooling.
Mf - The temperature, during cooling, at which transformation of austenite to martensite is substantially completed.
NOTE: All these changes except the formation of martensite occur at lower temperatures during cooling than during heating, and depend on the rate of change of temperature.
TUMBLING - Cleaning and/or deburring articles by rotating them in a cylinder containing cleaners and/or abrasives.
TWIST - Winding departure from flatness.
ULTIMATE STRENGTH - See TENSILE STRENGTH.
VACUUM DEGASSING - Refer to DEGASSING PROCESS.
VANADIUM - (Chemical Symbol V) - Gray - white hard metal used as a strong carbide and nitride former that refines steel grain size increasing strength and toughness.
VICKERS HARDNESS (TEST) - Standard method for measuring the hardness of metals, particularly those with extremely hard surfaces; the surface is subjected to a standard pressure for a standard length of time by means of a pyramid-shaped diamond. The diagonal of the resulting indention is measured under a microscope and the Vickers Hardness value read from a conversion table.
WAVY - Not flat. A slight wave following the direction of rolling and beyond the standard limitation for flatness.
WEDGE - A steel thickness profile wherein one edge is thicker than the center, which is thicker than the other edge.
WET CHEMICAL ANALYSIS - See CLASSICAL (WET) CHEMICAL ANALYSIS
WORK HARDENING - Increase in resistance to deformation (i.e. in hardness) produced by cold working.
YIELD POINT - The load per unit of original cross section at which, in soft steel, a marked increase in deformation occurs without increase in load. A steel loaded beyond its yield point deforms plastically and will not return to its original dimension when unloaded.
ZINC - (Chemical Symbol Zn) - Blue - white metal used extensively as a coating for steel (See GALVANIZING).
ZIRCONIUM - (Chemical Symbol Zr) – Silvery metal used as a strong deoxidizer and nitride former that imparts sulfide inclusion shape control to steel resulting in improved formability.
