U. S. Steel - Automotive Center

Glossary

Numerous terms are used in connection with the manufacture, sale and use of coated steel sheet. The following list defines the more common terms:

A | B | C | D | E | F | G | H | I | K | L | M | O | P | Q | R | S | T | U | W | Y

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	Aging - Changes in physical and mechanical properties that occur when low carbon steel is stored for some time. Aging is also accelerated by exposure of steel to elevated temperatures.

	Annealing - A process involving high-temperature heating and cooling of the as-rolled cold rolled steel substrate to make it softer and more formable.

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	Backer Coat - Usually refers to the coating on the reverse side of a prepainted sheet. The backer coating is generally not as narrowly specified with reference to its color, thickness and composition as is the topcoat.

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	Camber - The deviation of a side edge from a straight line, the measurement being taken on the concave side with a straight edge.

	Carbon Steel - Steel which owes its properties chiefly to carbon without substantial amounts of other alloying elements; also known as straight carbon steel or plain carbon steel.

	Chemical Treatment - An aqueous solution of corrosion-inhibiting chemicals, typically chromates or chromate/phosphate.

	Coil Breaks - Creases or ridges in sheet that appear as parallel lines across the direction of rolling, and that generally extend the full width of the sheet or strip.

	Cold Rolled Products - Flat rolled products for which the required final thickness has been obtained by rolling at room temperature.

	Color Standard - A painted sheet panel with a prescribed color of paint representing the precise color it is intended to produce in the prepainted sheet. The color standard will preferably also be expressed in terms of physical attributes of hue, lightness and saturation called tristimulus values or derivatives of these values. A complete color standard definition will usually include painted panels representative of the limits of acceptable deviation from the precise standard color as well.

	Commercial Steel (CS) - Sheet of this quality is for simple bending or moderate forming. Commercial Steel sheet can be bent flat upon itself in any direction at room temperature.

	Continuous Casting - A casting technique in which a cast shape is continuously withdrawn through the bottom of the mold as it solidifies, so that its length is not determined by mold dimensions.

	Conversion Coating - The chemical treatment film applied to the steel or metallic coated sheet prior to painting.

	Corrosion - Gradual chemical or electrochemical attack on a metal by atmospheric moisture or other agents.

	Critical Surface - Intended for material applied to critical exposed/painted applications where cosmetic surface imperfections are objectionable. The prime side surface will be free of repetitive type imperfections, gouges, scratches, scale and slivers. This surface can only be furnished as a pickled product.

	Crown - A contour on a sheet where the thickness increases from some edge measurement to the center.

	Cut Edge - Removal of the as-rolled hot mill edge. Coil ends are cropped back to gage when cut edge is ordered.

	Cut to Length - When a specific or discrete length is specified.

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	Deep Drawing - The process of working metal blanks in dies on a press into shapes which are usually more or less cup-like in character.

	Deep Drawing Steel (DDS) - Sheet of this designation should be used when Drawing Steel will not provide a sufficient degree of ductility for fabrication of parts having stringent drawing requirements, or applications that require the sheet be free from aging. This quality is made by special steelmaking and finishing practices.

	Dent Resistant - BH Series - Sheet of this designation is produced from aluminum-killed steel and offers a unique combination of as-received formability and final properties after fabrication. Sheet of this designation combines strength and high formability. Although this steel is non-aging at room temperature, it gains strength from work-hardening during fabrication and from carbon-aging during paint-baking. (Sometimes referred to as "bake hardenable.")

	Drawing - Forming recessed parts by forcing the plastic flow of metal in dies.

	Drawing Steel (DS) - Sheet of this quality has a greater degree of ductility and is more consistent in performance than Commercial Steel because of higher standards in production, selection and melting of the steel.

	Dry Film Thickness (DFT) - The thickness of the dry paint film.

	DS Type B Steel - Product intended for applications that require particularly severe drawing and forming.

	DUAL-TEN^® Steel - This is U. S. steel's brand of dual phase steel.

	Ductility - The ability to permit change of shape without fracture. In flat rolled steel, ductility is usually measured by hardness or mechanical properties in a tensile test.

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	Elongation - The percent increase of a given distance (usually 2 inches) prior to fracture during tensile testing.

	Embossed sheet - An embossed sheet is one having a prominent, impressed texture or pattern on its surface(s). If the defined texture is applied to essentially on surface only, it is most properly termed a coined surface. If the texture or pattern carries through the entire body of the sheet and appears on both surfaces it is a true embossed surface.

	Extra Deep Drawing Steel - Sheet of this designation has superior formability and excellent uniformity. It is produced from steel having a very low carbon content with stabilizing elements added to make it interstitial free. It is a non-aging steel sheet with high resistance to thinning during drawing and is suitable for critical forming applications.

	Extra Smooth Galvanized - An Extra-Smooth finish is imparted to hot-dip metallic-coated steel sheet by temper rolling after coating to decrease the surface relief that occurs when the molten coating solidifies. The spangle pattern (grain pattern) is made distinctly less visible by the matte finish imparted by the rolling operation. Most Extra-Smooth sheet is intended for either prepainted or post-painted applications.

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	Finish Coat - The top coat or exposed prime side paint film.

	Flatness - Flatness is a measure of a cut length sheet's ability to conform to a flat horizontal surface. Maximum deviation from that surface is the degree to which the sheet is out of flat. Flatness is often expressed quantitatively in either Steepness or I-Units.

	Flexibility - The degree to which a paint film can withstand deformation without significant change in color and appearance.

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	Gloss - The property of a surface related to its ability to reflect light. The most common type of gloss of interest to appearance attributes is specular gloss. The parameters which must be specified for the determination of this property are the angles of incidence of the light source, the angle of viewing of the gloss and the angular dispersions of the measuring beams.

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	Hardness - Resistance of metal to penetration of the surface.

	High Strength - Product intended for applications where greater strength is critical. High Strength typically begins at 35 ksi minimum yield strength.

	High Strength Low Alloy (HSLA) - A specific group of steels in which the strength levels are achieved by the addition of moderate amounts of alloying elements. The most common are Columbium, Vanadium or Titanium.

	Hot Rolled Sheet - Steel sheet that is processed to its final thickness by rolling at high temperatures on a specially designed hot-rolling facility.

	Hot Rolled Sheet Non-Temper Rolled - A U. S. Steel definition for product supplied as a coil directly off the Hot Strip Mill with no additional processing.

	Hot Rolled Sheet Pickled - A U. S. Steel definition for a mill edge coil that is pickled, oiled and temper rolled with coil ends cropped back to meet gage tolerances.

	Hot Rolled Sheet Pickled Non-Temper Rolled - A U. S. Steel definition for a mill edge coil that is pickled and oiled with coil ends cropped back to meet gage tolerances.

	Hot Rolled Sheet Products - Flat steel products that are brought to final thickness by rolling through a Hot Strip Mill at high temperatures.

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	Impact Test - A test which is intended to evaluate the brittleness, toughness, adhesion and hardness of paint films applied to metals by subjecting them to an indent impact force.

	Inclusions - Particles of foreign material (such as oxides, sulfides or silicates) in steel as cast.

	Inclusion Shape Control - The use of Rare Earth Metals or Calcium alloys to control the morphology of inclusions, in order to provide improved mechanical properties for select applications.

	Intercoat Adhesion - The adherence which is observed between the primer and topcoat of a paint system.

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	Killed Steel - Steel that is deoxidized by silicon or aluminum to reduce the oxygen content in the molten steel to a minimum prior to solidification of the metal. Killed steels have more uniform properties and chemical composition than other types.

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	Laminate - A composite construction of dissimilar materials, such as a metal and plastic film, usually made up as sheet product and intended to function as though it were a single material.

	Leveling - Flattening of rolled sheet by reducing or eliminating distortions.

	Lüders Lines - Elongated surface markings or depressions caused by localized plastic deformation that results from yield point elongation.

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	Matte Finish - A more uniform surface finish imparted to the sheet surface by temper rolling with shot-blasted rolls.

	Mechanical Properties - The properties of a material that reveal its elastic and inelastic behavior when force is applied, thereby indicating its suitability for mechanical applications.

	Mil - A term used to indicate the thickness of the paint film. A dry film thickness of 0.001", i.e., the standard dry film thickness after curing for several common paints, is one (1) mil.

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	Oil - Applied after pickling or temper rolling to assist customer handling by minimizing inter-wrap gouging, improve lubricity and provide a more rust resistant product.

	Oiled Sheet - Sheet product that is processed with the final step being the application of oil to the surface. Usually, the oil is intended to provide protection from rusting during shipment and storage. These oils are called rust-preventative oils. The oil may also serve to assist in the subsequent fabrication process, but this is not usually the main purpose. Oils used to enhance formability are often called "prelubes".

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	Pencil Hardness - A physical measurement of the hardness of a paint film which is based on the resistance of the film to cut-through by pencil leads of specified hardness. Pencil hardness values range between 2B and 5H.

	Pickling - Removing surface oxides from metals by a chemical reaction.

	Prelubricant - An oil coating that is applied to steel sheet to enhance formability (deep drawing). This lubricant is usually applied when the customer wishes to avoid the application of a forming lubricant in his plant.

	Pressure Vessel Steel (PVS) - Product intended for pressure vessels and similar end use applications.

	Primer Coat - The base coat of paint in a typical two-coat system. Primer coats are usually applied to produce a dry film thickness of approximately 0.2 mil.

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	Quality - A term used to denote the degree of perfection of the steel sheet. Often, for sheet products, relative quality refers to the degree of perfection of the surface, i.e., the lack of scratches, absence of slivers, etc. Quality can also refer to other attributes such as internal soundness, dimensional control, etc.

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	Reflectivity (Reflectance) - A term to indicate the percentage of reflected light from a painted surface. Considered a function of color rather than specular gloss. Reflectance percentages usually range from 80% to 90% for white colors to 5% to 15% for dark colors. Reflectivity standards vary for each industry and specific application.

	Registry Printing - Printing successive colors or figures in a precise pattern and with exact superposition.

	Roll Forming - A fabrication process whereby the metal sheet is deformed continuously in a linear manner by passing it through a consecutive series of rolls which produce a predetermined profile in it.

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	Salt spray test - A moisture and corrosion resistance test employing a controlled exposure of a painted sheet to a fog or mist of a salt solution, usually 5% sodium chloride, for a specified time period, say 500 or 1000 hours.

	Slit - When widths under 24" are obtained from wider sheets. The slitting operation results in a cut edge.

	Spangle - The spangle of a hot-dip coated sheet surface is the visual manifestation of the grains that form within the coating when it solidifies as the sheet emerges from the pot of molten coating metal. The spangle or grain varies in size, brightness and surface relief, depending upon a number of factors, most of which are related to the composition of the coating and cooling practices.

	Structural Steel - When this term is applied to steel sheet, it refers to the designation that is used for steel sheet that is produced to meet a specific level of strength and formability. The formability is expressed as percent elongation in a tensile test. Structural Steel is typically used for applications where the strength of the sheet is an important design criterion, i.e., load-bearing applications.

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	Tandem Coating Line - A continuous coil coating line having two or more coating machines and curing or baking ovens in the line so it is capable of applying and curing two coats of paint in one pass through the line.

	T-Bend 0-,1-,2-, etc. - A mechanical operation wherein a sheet sample is bent back upon itself with the inside bend radius specified in terms of the sheet thicknesses. Thus a 2-T Bend is a bend with an inside radius equivalent to two time the thickness of the metal sheet being tested.

	Tension Leveling - A mechanical operation wherein steel sheet, in coil form, is processed on a unit that stretches the product beyond its yield point to impart permanent deformation. The stretching operation assists to flatten the sheet. Tension leveling is considered the optimum process to achieve superior flatness characteristics.

	Temper Rolling - A light cold reduction of the sheet steel. This operation is performed to improve flatness, eliminate discontinuous yielding and to obtain a uniform surface.

	Tensile Strength - The maximum stress that a material can withstand. In tensile testing, the ratio of maximum load to original cross sectional area. Also called Ultimate Strength.

	Tint - A color modification resulting from the mixture of a white paint and colored paint such that the white is the predominant component and the resulting color is much less saturated that the pure color of the non-white pigment.

	Tolerance - A term that is used to quantify the allowable deviation from a dimension. For example, tolerances exist for the sheet thickness, width, flatness, camber, etc.

	Two-Coat System - The combination of a prime coat and a finish coat into a specified paint film. A typical 1 mil, two-coat system will have about 0.2 mil of primer coat and about 0.8 mil of finish coat.

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	Ultimate Strength - See Tensile Strength

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	Wash Coat - A very thin paint film applied to the back side of a prepainted sheet specified to have one finished side. The wash coat provides protection in coiling , storage, fabricating and handling.

	Weathering Steel - A steel using alloying elements such as Copper, Chromium, Silicon and Nickel to enhance resistance to atmospheric corrosion. (COR-TEN^® Steel)

	Wet Film Thickness - The thickness of the paint film immediately after coating and prior to curing. The required wet film thickness is dependent on the proportion of solids and solvents in the liquid paint for producing the appropriate dry film thickness.

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	Yield Point - The load or stress at which a marked increase in the deformation of the sheet occurs without increasing the applied load. Yield point is one of the characteristics of low-carbon steels after they have been annealed. The yield point is usually calculated using a tensile-test specimen, and it is the load that is commensurate with the point beyond the elastic limit at which the specimen lengthens considerably without an additional increase in load.

	Yield Strength - The stress at which a material exhibits a specified deviation from a linear proportionality between load and elongation. In the tension test, the load associated with an offset of 0.2% from linearity is used for many metals to calculate the yield strength.

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