Fractional Inches and Gauge to Decimal Inches and millimeters
|Fractional Inches and Gauge
Glossary of Terms
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. Stretcher strains and fluting can result from aging.
Alloy Steel: Alloy steel is a group of steels with different chemical composition, forming characteristics and strength levels from those normally present in carbon steel. Alloy steel normally has higher alloy content than steel classified as low strength low alloy steel. Alloy steel is often heat treated after part fabrication to develop the desired final physical properties.
Annealing: A process of controlled heating, soaking at elevated temperatures, and controlled cooling for the purpose of softening, developing a micro-structure, improve machinability, or obtaining a special set of physical or mechanical properties.
Brinell Hardness Test: In the Brinell Hardness Test, the value obtained by dividing the applied load (in kilograms) by the surface area of the impression (in square millimeters) resulting from forcing a hard steel or carbide ball onto the steel test sample. The higher the number the harder the steel.
Camber: This is the deviation from the edge straightness. The amount is determined along the concave side using straight edge and expressed as a measure per unit length, e.g. 1" in 20'.
Charpy V-Notch: This is a test to measure the impact strength, or notch toughness, of steel. It is of primary importance to evaluate steels for use where a brittle fracture hazard exists.
Coil Break: A deficit, exhibiting creases, a river type appearing, snaky pattern across a metal sheet running transverse to the coiling or rolling direction. The spacing is irregular and its location in the surface is very often random.
Cold Drawn Seamless (CDS): A term used to describe a fabrication process for round tubing. Produced to OD and ID dimensions by a process that pierces a hot rolled bar. Normally furnished in the "as drawn" condition. CDS offers good surface quality and greater mechanical properties than hot finished seamless tubing. Made from 1026 grade steel. Conforms to ASTM A519.
Cold Rolled Sheet Products: Flat rolled products for which the required thickness has been obtained by rolling HR bands or sheets without heating at approximately room temperature.
Commercial Quality (CQ): Sheet of this quality is for uses involving simple bending or moderate drawing. Commercial Quality sheet can be bent flat upon itself in any direction at room temperature.
Continuous Cast Steel: A process involving the pouring of liquid steel continuously as it solidifies into a desired semi-finished shape (square, rectangular, or other cross section). The shape is withdrawn from the mold according to a calculated rate based upon the cross section being cast. One of the biggest metallurgical advantages is the uniformity of the chemical composition and mechanical properties as compared to ingot cast steels. This results from the fact that the continuous cast slab solidifies in a few minutes, whereas in an ingot, complete solidification is not obtained until hours have gone by. Chemical segregation, characteristic of ingot cast steel, is virtually absent in continuous cast slabs.
Deoxidizing: The removal of oxygen from molten steel by use of suitable elements (i.e. silicon, aluminum) that react with oxygen readily.
Direct Rolling: A relatively new process whereby a continuous cast slab is moved directly into a hot finish mill for rolling into sheet or plate. This process avoids costly re-heating furnaces.
Drawing Quality (DQ): As compared with sheet of Commercial Quality, Drawing Quality sheet has a greater degree of ductility and is more consistent in performance. The greater ductility and uniformity results from higher standards of production, selection and processing of the steel.
Drawn Over Mandrel (DOM): A term used to describe a fabrication process for round tubing. DOM has very little wall variation and no spiraling eccentricity. The tube is formed and welded from strip steel which has very little gauge variation. The tube is then cold drawn to size, causing the weld seam to virtually disappear. Tubing 10 ga and lighter is made from 1020 grade steel, heavier than 10 ga is made from 1026. Conforms to ASTM A513 Type 5 (mandrel drawn).
Ductility: Is a measure of the ability of steel to undergo permanent changes without rupturing.
Edges: Mill edge is the normal edge produced in hot rolling and it does not conform to any definite contour. Mill edge product may contain some edge imperfections the more common types of which are, checked edges, thin edges (feather) and damaged edges due to handling or processing. These edge conditions are detrimental where joining of the mill edges by welding is practiced. When the customer intends to shear or blank, a sufficient width allowance should be made by the purchaser to assure obtaining the desired shape and size of the pattern sheet.
Elongation: The amount of extension a test specimen udergoes to fracture during tensile testing. A measurement compares a before and after unit gauge length indexed into the specimen. The change is expressed numerically as a percentage of the original gauge length.
Electric Resistance Welded Tubes: Tubes that are produced from a cold rolled or hot rolled scale-free strip which is formed by rolls at room temperature into a tubular shape. Welding takes place as an electric current heats the two edges of the strip as they are pressed together. Only a narrow band of metal is heated while the rest of the tube remains at room temperature. The weld flash is always trimmed off the outside of the tube. The flash can also be trimmed from the inside by special tooling.
Electrogalvanized: A commonly used term to describe steel that has been plated with zinc using an electric current through an electrolyte. Proper name is Electrolytic Zinc Coated Sheet.
Fatigue: The tendency for a metal to break under conditions of repeated cyclic stressing considerably below the ultimate tensile strength.
Fluting: Fluting is a series of sharp parallel kinks or creases occurring in the arc when sheet steel is formed cylindrically, as to stretch the outer surface well beyond its yield point.
Friction Digs: A series of relatively short scratches variable in form and severity.
Galvanized: A term long used to describe steel coated with zinc. The term is associated with the hot-dip process but zinc coating can also be applied by electroplating. The hot-dip process consists of passing the steel through a bath of molten zinc. The electroplating process consists of the application of zinc by electrolytic deposition.
Galvannealed: Is a galvanized sheet steel which is altered by heat treatments or other processes immediately after coating, before the zinc solidifies. The coating produced consists entirely of iron zinc alloy and has a rougher appearance than the surface of regular coating. Sheets produced in this manner are dull gray in color, have no spangle, and after proper preparation, are well suited for painting.
Hardenability: Refers to the depth to which hardness penetrates. It is that property which determines the depth and distribution of hardness induced by quenching.
High Strength Steel: High strength structural quality sheet steel is a carbon/manganese steel... with a minimum specified yield strength of 35 KSI or greater (regardless of chemistry of processing used to achieve that strength level).
Hot Rolled: Describes steel products that are brought to the appropriate finished size by rolling at elevated temperatures.
Hot Rolled Plate: Product is defined in ASTM A6 paragraph 3.1. For widths over 8" to 48" thickness range is 0.230" and over. For widths over 48", thickness range is 0.180" and over. Plate product is always cut to length.
Hot Rolled Sheet: Hot rolled sheet product is defined by ASTM A568. For 12" to 48" inclusive, thickness range is 0.044" to 0.230", exclusive; over 48" wide, thickness range is 0.044" to 0.180", exclusive. This specification is the size reference for all ASTM sheet specifications.
Ingot: The solidified steel formed in a mold for subsequent rolling or forging.
KSI: K Equals 1000 PSI... thus the term is actually K (1000) PSI. The P has been dropped... and KSI is the new term. (i.e. 50 KSI = 50,000 PSI)
Killed Steel: Steel deoxidized by silicon or aluminum to reduce the oxygen content to a minimum so that no reaction occurs during solidification of the metal. Killed Steels have more uniform properties and chemical composition than other types.
Laminations: Imperfections resulting from the presence of blisters, seams or foreign inclusions, and sometimes visible on the surface of the metal.
Oiled: Application of a suitable oil to flat rolled steel to retard rusting. When surface is a consideration, it is also desirable in reducing friction scratches that may develop in transit. The oil coating is not intended to serve as a lubricant for subsequent fabrication.
Pipe Lamination: A term used to describe a defect in steel, generally caused in the pouring of steel. It usually manifests itself as a void in the centerline of the ingot or slab.
Porosity: The existence of fine holes (pores) in steel.
Quenching and Tempering: A process by which steel is rapidly cooled from above its upper critical temperature to a temperature far below this range. Water or oil is normally used to accelerate the cooling. In the as quenched condition, the product is not suitable for most commercial applications because of its lower ductility and high hardness. The steel must, therefore, be tempered in order to soften it somewhat to improve its ductility and toughness. Tempering is a heat treatment done at lower temperatures usually in the range between 400 degrees Fahrenheit and 1200 degrees Fahrenheit.
Rockwell Hardness Test: Forcing a cone-shaped diamond or hardened steel ball into the specimen being tested under standard pressure. The depth of penetration is an indication of the Rockwell Hardness.
Scale: An iron oxide formed on the surface of hot steel, sometimes in the form of large sheets which fall of when the steel is rolled.
Slab: A semi-finished steel block having an oblong cross-section in which width is at least twice thickness. It differs from a bloom which has a square, cross-section.
Slitting: The longitudinal splitting of the overall width of a flat product through rotary knives mounted on a rotary arbor to reduce the original width or to cut two or more separate strips.
Stress Relieving: A process of reducing residual stresses in a metal object by heating the object to a suitable temperature and holding for a sufficient time. This treatment may be applied to relieve stresses induced by flattening, straightening, machining or welding.
Strip (HR): Flat steel produced by rolling single width, or multiple width and cut to final specified width by slitting. Final product width is 12 inches or less.
Temper: A condition produced in sheet steel by mechanical, chemical or thermal treatment. A given steel may be in the fully softened or annealed temper, or it may be cold worked to the hard temper, or further to spring temper. Intermediate tempers produced by cold working (rolling) are called "quarter-hard", "half-hard", and "three-quarters hard", and are determined by the amount of cold reduction.
Tensile Strength: The maximum tensile stress which a material is capable of sustaining. Tensile strength is calculated from the maximum load during tension test carried to rupture.
Yield Point: The load per unit of original cross-section area which a marked increase in the deformation of the specimen occurs without increase of load. It is usually calculated from the load determined by the drop of the beam of the testing machine or by use of dividers.
Yield Strength: The stress at which a material exhibits a specified deviation from proportionality of stress and stain. An offset of 0.20% is used for many metals. The point measured in PSI at which the metal cross-section will no longer return to its original shape.