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Glossary | Shelby Steel
  • The process in which the physical and mechanical properties of low carbon steel change over time. 

  • Artificial aging is the treatment of a metal alloy at elevated temperatures so as to accelerate the changes in the properties.
  • A metal made by combining two or more metallic elements to create a substance that has the chemical and mechanical properties desired for a given application.   

  • Alloy steel is iron ore, carbon, and various other metallic elements, such as manganese , nickel, chromium, molybdenum, vanadium, and silicon.
  • A heat treatment process used to reduce hardness, increase ductility, and help eliminate internal stresses in steel.
Annealing Stain
  • A discoloration resulting from residue or oxidation during the annealing process.
Base Steel Thickness
  • The thickness of a sheet steel without any coatings.
Bend Test
  • A test used to determine steel ductility, during which steel is bent either with or against the grain.
  • The amount of curvature or the deviation from a straight line of the side edge of a steel sheet.

  • The measurement is taken on the concave side of the sheet, with a straight edge.


Center Buckle
  • Waves in the center of the steel (in the rolling direction), as opposed to waves on the edges of the steel which is seen in "edge waves".
Chatter Marks
  • A lightly visible surface defect of light/dark transitional stripes caused by an undulation of the strip (in the micrometer range) from in-line roller variations.
Coating Weight
  • The thickness of the zinc and/or aluminum which is applied to the base substrate (hot rolled or cold rolled) in Galvanized, Electro-Galvanized, Galvannealed,  Aluminized and Galvalume sheet steel.
Coil Breaks
  • Coil Breaks (also known as cross breaks) are creases which appear as lines transverse to the rolling direction of the steel and generally extend across the width of the steel.

  • The presence of Coil Breaks is a clear indication of very formable and ductile material.
Commercial Steel (CS)
  • The designation of a grade of steel that is suitable for moderate forming processes.  It is ductile enough to be bent flat upon itself in any direction at room temperature without fracturing.

  • Also known as CQ (commercial quality), the term is commonly used to designate mild steel.
Drawing Steel (DS)
  • A quality designation of carbon steel, typically containing less than 0.05 percent carbon, DS is more ductile than commercial quality (CQ/CS) and is suitable for producing deep-drawn parts or any other parts needing severe deformation.
  • Ductility is a measure of a metal's ability to withstand tensile stress (any force that pulls the two ends of a material away from each other).

  • Referring to metal, the  term "ductile" is defined as capable of being stretched into a thin wire without becoming weaker or more brittle in the process.
  • The ability of steel to resist a distorting influence and to return to its original shape and size when the forces causing the deformation are removed.
  • A process in which a thin coating of zinc is bonded to steel in order to protect against corrosion.

  • The process involves electroplating, which consists of running a current of electricity through a saline/zinc solution with a zinc anode and steel conductor.
  • Elongation is a measure of the ductility of steel as determined by a tension test.

  • Higher elongation equals higher ductility.  Elongation measures how much bending and shaping a material can withstand without breaking.

  • Elongation is inversely proportional to hardness, tensile strength, and modulus. The greater a material’s hardness, tensile strength, and modulus, the less it will elongate under stress.


Extra Smooth (XS)
  • A more uniform finish imparted to Galvanized or Galvalume steel by temper rolling after the substrate has been coated.

  • Most extra smooth steel is for prepaint applications where surface appearance is critical.
  • A condition in coated sheet where portions of the coating loosen due to inadequate adhesion.
  • The measure of a steel sheet's ability to conform to a flat horizontal surface.

  • The degree to which a sheet is out of flat is the called the maximum deviation.
Forming Steel (FS)
  • This category is also known as Drawing Quality (DQ). Softer than commercial steel, it applies to coated sheet products such as galvanized, galvannealed, and aluminized.
  • A break in steel which will first be observed at the surface.
Friction Scratches
  • Also known as galling, friction scratches are short abrasions caused by the rubbing of laps or sheets.
Full Hard (FH)
  • Containing a rockwell of greater than B84, full hard steel is rolled without subseqent annealing, and has elevated yield and tensile strengths, very low elongations, and is not suited for severe bending or drawing.
  • Galfan (ZA) is a zinc-aluminium alloy (95% Zn, 5% Al) coating that provides excellent corrosion protection and forming properties compared to traditional zinc coating.
  • Cold rolled sheets containing a 55% aluminum and 43% zinc coating, which is applied in a hot-dip process similar to galvanized coating, and offerring greater rust resistance than galvanized sheet.
  • A term used to describe steel sheets that are coated with zinc in order to promote corrosion resistance.

  • This uses the hot–dip process but the zinc coating can also be applied by electroplating.

  • The hot–dip process involves passing the steel through a bath of molten zinc.

  • The electroplating process consists of the application of zinc by electrolytic deposition.

  • Galvannealed steel is galvanized sheet steel which is altered immediately before the zinc solidifies by either heat treatments or other processes.

  • The coating consists entirely of iron zinc alloy and is rougher than that of a regular coating.

  • The produced sheets have a dull gray color and after proper preparation, are well suited for painting.

  • Gauge (sometimes spelled gage) is the thickness of steel sheet.
  • An instrument used to measure the reflectivity of a steel finish.
Half Hard
  • Cold rolled steel which will generally only accept a 90 degree bend across the direction of rolling, around a radius equal to the thickness of the steel.

  • The rockwell range of the steel is B 70-85.
  • The resistance of a material to deformation, indentation, or scratching.

  • The primary hardness test for sheet steel is a the Rockwell hardness test.
Healed Over Scratch
  • A scratch that occurred in a mill operation but was masked during subsequent rolling. It is possible that it could open up during forming.
High Strength
  • Steel usually starting at 35,000# minimum yield strength.
High Strength Low Alloy
  • High Strength Low Alloy (HSLA) steel is a type of carbon steel that has small amounts of alloying elements (i.e. Vanadium, Molybdenum, Columbium, Titanium) added to its chemical composition in order to increase the strength and toughness of the steel.
Hot Dip Steel
  • Steel sheets with a zinc coating that is applied by passing the steel through a bath of molten zinc, which  enhances the steel’s corrosion resistance.

  • In general, the corrosion resistance of the coating is directly proportional to the coating thickness.
Impact Testing
  • A procedure used to determine how resistance steel is to fracturing under extreme conditions.
  • Foreign particles (i.e., silicates, oxides, sulfides) in steel that may compromise its physical integrity.

  • These particles of non–metallic material are entrapped mechanically, formed during solidification, or by subsequent reaction within the solid metal.
Inclusion Mark
  • Steel surface defect where an actual inclusion or the void it left behind is observed.
Inner Diameter (ID)
  • The measurement of the inside diameter of a steel coil.
Intermediate Temper
  •  Intermediate tempers produced by cold working (rolling or drawing) are called "quarter-hard", "half-hard" and "three quarters hard", and are determined by the amount of cold reduction and the resulting tensile properties.
Knife Mark
  • A continuous scratch caused by the sheet contacting the slitter knife near a slit edge.

  • Flat and thin subsurface separations present inside metal plate, parallel to the surface of the plates.

  • The sources of this defect are inherent discontinuities present in metal such as inclusion and porosity, which are flattened during the rolling process.
Lap Weld
  • Coil ends are “lapped” over one another and then welded for production purposes.

  • As a result, the lapped area has a thickness that is doubled.
  • Flattening of a steel coil through a series of rollers in order to reduce distortions in thickness, shape and/or surface quality.
Line Stop
  • An area of a galvanized or other type of coated coil characterized by irregular and questionable coating integrity due to the coating line being halted while the coil was in process.
Lockseam Test
  • A procedure conducted on galvanized steel in order to determine zinc adherence to the substrate.
Low Carbon
  • Steel with a carbon content below 0.25%, as opposed to High Carbon steel, which has a carbon content in excess of 0.50%.
  • Ultra strong steel with tensile strengths ranging from 130000–215000 psi.
Matte Finish
  • Cold Rolled surface roughness (or brightness), measured using a profilometer.
  • A tool used to measure steel thickness (gauge).
Mild Steel
  • Carbon steel with a maximum carbon content of 0.15%.


Mill Edge
  • An untreated edge (not slit), with a somewhat uneven contour.
Mill Scale
  • Mill Scale, also know as just "Scale" is the flaky surface of hot rolled steel, which consists of iron oxides.

  • The best way to remove mill scale is by pickling.


Oil Can
  • Also known as a trapped center buckle, this is a tight wave or undulation appearing in the center of the sheet.
  • The application of dried oil to steel in order to slow rusting.

  • An acid bath (pickling liquor) is used prior to the oil application to remove scale and other impurities from the surface of the steel.
Olsen Test
  • A cupping test made on an Olsen machine helps to determine ductility and deep drawing properties of steel.

  • The test simulates a deep drawing operation and is continued until the cup is formed or the steel sample fractures.

  • Ductility and drawing properties are judged by the position of the break, depth of the cup, condition of the surface after the break, et cetera.

  • The uneven wrapping during the winding of a steel coil.

  • Typical causes of oscillation are improper alignment of rolls over which the metal passes and insufficient rewind tension.
Outer Diameter (OD)
  • The measurement of the outside diameter of a steel coil.
  • A steel sheet that is not perfectly square or rectangular.

  • The length and width of a sheet may measure correctly, but the sheet is still "out of square".

  • A "square" sheet has perfect 90° angles in each of the four corners.

  • To check the squareness of a sheet without measuring the angles, diagonal measurements can be used.

  • The amount a sheet is out of square is the difference between diagonal
    measurements divided by two.

Passivation Treatment
  • A thin chemical film which is applied to the surface of the coated sheet (e.g.galvanized steel) to minimize  wet storage stain (white rust).

  • Although galvanized steel in typical conditions is highly tolerant of diverse atmospheric and environmental conditions, passivation-quenching can be done when environmental, storage or shipping conditions warrant.

  • Generally, passivation coatings last about six weeks before being consumed. At that time, galvanized steel will begin to weather naturally.

  • Passivation should be avoided if the part is going to be painted or powder coated, as it can affect adhesion of the top coat system.



  • The separation of the coating from the steel substrate which occurs on galvanized, aluminized, and other metallic-coated steel.
  • Also known as phosphating or phosphate conversion coating, phosphatizing is a surface pre-treatment used to prevent corrosion and to prepare the steel for painting or coating.

  • It is termed a conversion coating because, unlike paint or traditional coatings, it does not lie on the surface of the metal, but rather the surface of the metal is chemically changed to a new substance.

  • Therefore, there is no coating to chip or scratch, which eliminates the exposure of the base material to corrosion and wear.

Pickle Patch
  • An area of heavy scale that was not removed after pickling or other processing.
Pickle Stain
  • A discoloration due to excessive acid solution or the steel's exposure to it.
  • A steel surface treatment that uses strong acids (pickle liquor) to remove impurities such as stains, inorganic contaminants, rust, or scale.
  • Shearing or blanking steel sheets in order to meet closer than standard width, length and out–of–square tolerances.
  • A test measurement to determine the hardness of the steel.

  • In low–carbon steels, it can indicate approximate yield and tensile strengths.
  • A surface defect caused by mill scale being rolled into the steel surface.
Roll Mark
  • A small depressed area on a rolled steel product that is caused by the opposite condition on the roll.
Roll Forming
  • Roll Forming (aka rollforming) is a process in which a long strip of steel is passed though consecutive stands of rolls, each preforming an incremental bend in the steel until the desired profile is obtained.
Rub Mark
  • Very fine scratches or abrasions caused by metal-to-metals contact.
Salt Spray Test
  • A procedure that exposes steel to the corrosive effects of saltwater in order to determine its coating longevity.
Secondary Steel
  • Material that does not meet the original customer’s specifications due to a variety of reasons.

  • Secondary is sold at a discount compared to prime steel and may be quite suitable for other applications.
  • A coil's sides and edges, which, ideally, are smooth, straight, and free from damage.
Slit Edge
  • An edge that is produced from the slitting process, resulting in edges with a tighter width tolerance.


  • Winding a steel coil in a manner that creates a controlled oscillation on the sidewalls of a coil.

  • It is a very slow and gradual movement of the exit reel, approximately 3/8" back and forth  in one direction and then 3/8" back and forth  in the other direction for a  3/4" overall controlled oscillation or stagger.

  • Staggerwinding is very useful when trying to minimize re-distortion in the strip from a build-up condition.

  • Maximum stagger is 2-1/2" in either direction.

  • Stains (Oil Stains) are surface discoloration, varying from dark brown to white, resulting from incomplete evaporation and/or oxidation of the surface by lubricants during thermal treatment.


Tandem Mill
  • A type of cold rolling mill where rolling (to reduce thickness and improve flatness) is done in one pass.

  • In a traditional rolling mill, rolling is done in several passes, but in tandem mills there are several stands (>=2 stands) and reductions take place successively.


  • A coil shape defect whereby the coil wraps protrude towards one side of the coil so that the sidewall of the coil is conical rather than flat.
  • A condition produced in sheet steel by different mechanical, chemical or thermal treatment.

  • Steel may be fully-softened to an annealed temper, be cold worked to the hard temper or worked further to a spring temper.
Temper Passing
  • Temper Passing (also known as Skin Passing) is a cold reducing process of rolling out and compressing a steel coil under very high pressure between two work rolls to flatten and elongate it.

  • The process strives to eliminate coil memory and decrease the material thickness between 1.5 - 2%, thereby elongating the coil by the same percentage points, without appreciable spreading or widthwise elongation.

Tensile Strength
  • Tensile strength (also known as Ultimate Tensile Strength) refers to the amount of tensile (stretching) stress a material can withstand before breaking or failing.

  • It is calculated by dividing the area (cross section) of the material being tested by the stress placed on the material, generally expressed in terms of pounds per square inch (PSI) of material.
Triple Spot Test
  • A process that measures the weight of the coating on hot-dipped steel in three separate places along the width of the steel: the centerline, and at least two inches from each edge.
Vacuum Degassing
  • A steel making process that reduces or eliminates dissolved gasses, especially oxygen and nitrogen.

  • Vacuum degassing takes place after the molten steel has left the furnace and before the steel is poured into ingots or processed through a caster.

  • It is used to produce ultra-low carbon steels with high drawing and formability capabilities.

  • This is particularly useful for automotive body applications.

Vitrenamel Sheet
  • Cold rolled sheet steel that has been processed for porcelain (vitreous) enameling operations.

  • Steels that are used for enameling must have specialized properties in order to be coated successfully and obtain good adhesion between the enamel and steel surface.

  • Porcelain enamel coatings are inorganic and form coatings that are much harder than paint coatings.

  • They are ideal for applications that require both hardness to prevent scratching and elevated temperature stability, such as stove tops, oven cavities, laundry appliances, hot-water heater tanks and cookware.

Water Stain
  • A cosmetic surface defect, which is created by the oxidation of the surface with a water film when there is an absence of circulating air, such as between the wraps of a coil or the sheets in a bundle.

  • The appearance varies from white to a more severe gray or black color.
  • Coils that have been welded together to form a single, longer length for more efficient production.

  • The area near the weld is typically poor in strength, surface condition and coating adhension.
White Annealing
  •  A heat treatment process carried out on pickled steel with the objective of eliminating the hydrogen that has entered the steel during the pickling operation, thus removing any tendency to hydrogen embrittlement.
White Rust
  • Corrosion of galvanized steel that occurs when material is exposed to moisture.

  • The white powder is actually zinc hydroxide (the substance formed when zinc reacts with water and air) and it gradually consumes the zinc coating.

  • This process is most likely to happen in wet conditions with inadequate air circulation.

Yield Point
  •  The point at which, while steel is under a stress load, it ceases to behave elastically (see Yield Strength below).

  • The yield point marks the end of elastic behavior and the beginning of plastic behavior.
Yield Point Elongation
  • Yield Point Elongation (YPE) is the difference between the elongation of the specimen at the start and at the finish of discontinuous yielding (the area in which an increase in strain occurs without an increase in stress).
Yield Strength
  • The stress value that steel can take while still showing elastic behavior.  Any stress applied to steel above this value will take it into the plastic zone.

  • There are two types of deformation that occurs in steel:  elastic and plastic

  • Elastic:  the steel deforms because of a stress load imposed on the sample, and when the load is reduced or removed, the steel returns to its original shape, like a spring. There is no permanent deformation.

  • Plastic: the steel deforms because of an imposed load and the resultant deformation is retained after the load is reduced or removed.  A bent paper clip is an example as it retains its shape after you have bent it.  You have exceeded the yield strength of the steel in the paper clip.

  • The 24th most abundant chemical element in the earth's crust, Zinc (Zn) is used in steel manufacturing to inhibit rust formation.
Zinc Stringers
  • A surface defect featuring a coarse coating and zinc ridges.

  • When zinc adherence is good and proper coating weights are present, the stringers will have no harmful effect on the life of the sheet.
  • A corrosion-resistant coated-steel product trademarked by Metal Coatings International.

  • The steel is  processed with a proprietary, two-coat system.

  • The base coat is a chromium-based inorganic material called Dacromet.

  • After baking, the coil is coated with a second material called Zincromet, which is an an epoxy-based, zinc-rich topcoat, and baked for a second time.

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