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                          Heat Treatment Requirements

Oil Hardening
A process of hardening a ferrous alloy of suitable composition by heating within or above the transformation range and quenching in oil.

Oil Stain Aluminum
Stain produced by the incomplete burning of the lubricants on the surface of the sheet. Rolling subsequent to staining will change color from darker browns to lighter browns down to white.

Oil-Hardening Steel
Steel adaptable to hardening by heat treatment and quenching in oil.

Olsen (Ductility) Test
A method of measuring the ductility and drawing properties of strip or sheet metal which involves determination of the width and depth of impression. The test simulating a deep drawing operation is made by a standard steel ball under pressure, continuing until the cup formed from the metal sample fractures. Readings are in thousandths of an inch. This test is sometimes used to detect stretcher straining and indicates the surface finish after drawing, similar to the Erichsen ductility test.

Open Surface
Rough surface on black plate, sheet or strip, resulting from imperfection in the original steel bars from which the plate was rolled.

Open-Hearth Furnace
A reverberatory melting furnace with a shallow hearth and a low roof. The flame passes over the charge in the hearth, causing the charge to be heated both by direct flame and radiation from the roof and sidewalls of the furnace. In ferrous industry, the furnace is regenerative.

Open-Hearth Process
Process of making steel by heating the metal in the hearth of a regenerative furnace. In the basic open-hearth steel process, the lining of the hearth is basic, usually magnesite; whereas in the acid open-hearth steel process, an acid material, silica, is used as the furnace lining and pig iron, extremely low in phosphorous (less than 0.04%), is the raw material charged in.

Orange Peel
A pebble-grain surface which develops in forming of metals having coarse grains.

Orange Peel (effect)
A surface roughening (defect) encountered in forming products from metal stock that has a coarse grain size. It is due to uneven flow or to the appearance of the overly large grains usually the result of annealing at too high a temperature. Also referred to as pebbles and alligator skin.

Ore
A mineral from which metal is (or may be) extracted.

Orientation (crystal)
Arrangement of certain crystal axes or crystal planes in a crystalline aggregate with respect to a given direction or plane. If there is any tendency for one arrangement to predominate, it is known as the preferred orientation; in the absence of any such preference, random orientation exists.

Orientation (crystal)
Directions in space of the axes of the lattice of a crystal with respect to a chosen reference or coordinate system.

Oscillated Wound or Scroll Wound
A method of even winding metal strip or wire on to a reel or mandrel wherein the strands are uniformly over-lapped. Sometimes termed stagger wound or vibrated wound. The opposite of ribbon wound.

Overaging
Aging under conditions of time and temperature greater than those required to obtain maximum change in a certain property, so that the property is altered in the direction of the initial value.

Overaging
Aging under conditions of time and temperature greater than those required to obtain maximum change in a certain property.

Overaging
Aging under conditions of time and temperature greater than those required to obtain maximum strength.

Overheating
Heating a metal or alloy to such a high temperature that its properties are impaired. When the original properties cannot be restored by further heat treating, by mechanical working, or by combination of working and heat treating, the overheating is known as burning.

Overheating
Heating a metal or alloy to such a high temperature that its properties are impaired. When the original properties cannot be restored by further heat treating, by mechanical working or by a combination of working and heat treating, the overheating is known as burning.

Oxidation
The addition of oxygen to a compound. Exposure to atmosphere sometimes results in oxidation of the exposed surface, hence a staining or discoloration. This effect is increased with temperature increase.

Oxidation
(1) A reaction in which there is an increase in valence resulting from a loss of electrons. (2) Chemical combination with oxygen to form an oxide.

Oxide
Compound of oxygen with another element.

Oxidized Surface
A surface having a thin, tightly adhering oxidized skin.

Oxygen Lance
A length of pipe used to convey oxygen onto a bath of molten metal.

Oxygen-Free Copper
Electrolytic copper free from cuprous oxide, produced without the use of residual metallic or metalloidal deoxidizers.