DICTIONARY OF INDUSTRY TERMS

D

Decalescence - The absorption of heat, due to internal changes, which occurs when steel is heated through the critical temperature range.

Decarburization - The loss of carbon from the surface of solid steel during heating, forging, hot rolling, etc.

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 Etching - Etching, for examination at low magnification, by a reagent that attacks the metal to a much greater extent than is normal for microscopic examination-may bring out such features as abnormal grain size segregation cracks or grain flow.

Deoxidize - The removal of oxygen, present as iron oxide, from molten steel by adding a deoxidizing agent such as manganese, silicon or aluminum.

Deoxidized Sheets - Hot rolled sheets that have been bright annealed.

Depth of Penetration - The depth to which appreciable hardening occurs when steel is quenched from its hardening temperature.

Diamond Pyramid Hardness Test - An indentation hardness test employing a 136° diamond pyramid indenter and variable loads enabling the use of one hardness scale for all ranges of hardness from soft lead to tungsten carbide.

Differential Heating - Heating so that portions of an article reach different temperatures to produce different properties upon cooling.

Distortion - A change in shape (usually refers to changes of shape caused by internal stress).

Double Vacuum Melting - Ingots made by the vacuum induction melting method are re-melted and further refined by the consumable electrode method.

Drawing - Drawing may refer to the pulling of steel through a die, as in drawing wire, or deforming steel in dies on a press (deep drawing).

Drawing Back - Reheating after hardening to a temperature below the critical for the purpose of improving the ductility and or lowering the hardness of the steel.

Drawing Quality - Flat rolled steel which can withstand extreme pressing, drawing or forming, etc. without creating defects. Produced from deep-drawing rimmed steels or extra deep-drawing aluminum-killed steels which are special rolled and processed.

Ductility - The ability to permit change of shape without fracture. In steel, ductility is usually measured by elongation and reduction of area as determined in a tensile test.

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