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Grinding where the operator manually forces the wheel against the work, or vice versa. It often implies casual manipulation of either grinder or work to achieve the desired result. Dimensions and tolerances frequently are not specified, or are only loosely specified; the operator relies mainly on visual inspection to determine how much grinding should be done. Contrast with precision grinding.
The distance along the strain coordinate between the initial portion of a stress-strain curve and a parallel line that intersects the stress-strain curve at a value of stress (commonly 0.2%) that is used as a measure of the yield strength. Used for materials that have no obvious yield point.
offset yield strength
The stress at which the strain exceeds by a specific amount (the offset) an extension of the initial, approximately linear, proportional portion of the stress-strain curve. It is expressed in force per unit area.
Hardening of carbon steel in an oil bath.
Olsen ductility test
A cupping test in which a piece of sheet metal, restrained except at the center, is deformed by a standard steel ball until fracture occurs. The height of the cup at the time of fracture is a measure of the ductility.
open-back inclinable press
A vertical crank press that can be inclined so that the bed will have an inclination generally varying from 0 to 30°. The formed parts slide off through an opening in the back. It is often called an OBI press.
The hot mechanical forming of metals between flat or shaped dies in which metal flow is not completely restricted. Also known as hand or smith forging. See also hand forge (smith forge).
Dies with flat surfaces that are used for preforming stock or producing hand forgings.
open hearth furnace
A reverberatory melting furnace with a shallow hearth and a low roof. The flame passes over the charge on the hearth, causing the charge to be heated both by direct flame and by radiation from the roof and sidewalls of the furnace. See also reverberatory furnace.
open rod press
A hydraulic press in which the slide is guided by vertical, cylindrical rods (usually four) that also serve to hold the crown and bed in position.
optical emission spectroscopy
Pertaining to emission spectroscopy in the near-ultraviolet, visible, or near-infrared wavelength regions of the electromagnetic spectrum. See also electromagnetic radiation.
A surface roughening in the form of a pebble-grained pattern that occurs when a metal of unusually coarse grain size is stressed beyond its elastic limit. Also called pebbles and alligator skin.
See rotary forging.
The crystal structure of a solid solution in which the atoms of different elements seek preferred lattice positions. Contrast with disordered structure.
A natural mineral that may be mined and treated for the extraction of any of its components, metallic or otherwise, at a profit.
Same as mineral dressing.
Arrangements in space of the axes of the lattice of a crystal with respect to a chosen reference or coordinate system. See also preferred orientation.
original crack size (ao)
The physical crack size at the start of testing.
oscillating die press
A small high-speed metal forming press in which the die and punch move horizontally with the strip during the working stroke. Through a reciprocating motion, the die and punch return to their original positions to begin the next stroke.
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.
Bending metal through a greater arc than that required in the finished part to compensate for springback.
A condition wherein a metal curves upward on leaving the rolls because of the higher speed of the lower roll.
A mechanical press with the driving mechanism mounted in or on the crown or upper parts of the uprights.
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.
In resistance seam welding, the area in a given weld remelted by the succeeding weld.
Powder particles larger than the maximum permitted by a particle size specification.
In fatigue testing, cycling at a stress level higher than that used at the end of the test.
(1) A reaction in which there is an increase in valence resulting from a loss of electrons. Contrast with reduction. (2) A corrosion reaction in which the corroded metal forms an oxide; usually applied to reaction with a gas containing elemental oxygen, such as air. Elevated temperatures increase the rate of oxidation. (3) A chemical reaction in which one substance is changed to another by oxygen combining with the substance. Much of the dross from holding and melting furnaces is the result of oxidation of the alloy held in the furnace.
Reduction in the amount of metal or alloy through oxidation.
(1) A corrosive wear process in which chemical reaction with oxygen or oxidizing environment predominates. (2) A type of wear resulting from the sliding action between two metallic components that generates oxide films on the metal surfaces. These oxide films prevent the formation of a metallic bond between the sliding surfaces, resulting in fine wear debris and low wear rates.
oxidized steel surface
Surface having a thin, tightly adhering oxidized skin (from straw to blue in color), extending in from the edge of a coil or sheet.
A compound that causes oxidation, thereby itself being reduced.
A furnace atmosphere with an oversupply of oxygen that tends to oxidize materials placed in it.
A gas flame produced with excess oxygen in the inner flame that has an oxidizing effect. See also neutral flame and reducing flame.
An oxyfuel gas cutting process in which the fuel gas is acetylene.
An oxyfuel gas welding process in which the fuel gas is acetylene.
oxyfuel gas cutting
Any of a group of processes used to sever metals by means of chemical reaction between hot base metal and a fine stream of oxygen. The necessary metal temperature is maintained by gas flames resulting from combustion of a specific fuel gas such as acetylene, hydrogen, natural gas, propane, propylene, or Mapp gas (stabilized methylacetylene-propadiene).
oxyfuel gas welding (OFW)
Any of a group of processes used to fuse metals together by heating them with gas flames resulting from combustion of a specific fuel gas such as acetylene, hydrogen, natural gas, or propane. The process may be used with or without the application of pressure to the joint, and with or without adding any filler metal.
See preferred term oxygen cutting.
oxygen arc cutting
An oxygen cutting process used to sever metals by means of the chemical reaction of oxygen with the base metal at elevated temperatures. The necessary temperature is maintained by an arc between a consumable tubular electrode and the base metal.
A group of cutting processes used to sever or remove metals by means of the chemical reaction between oxygen and the base metal at elevated temperatures. In the case of oxidation-resistant metals, the reaction is facilitated by the use of a chemical flux or metal powder. See also chemical flux cutting , metal powder cutting , oxyfuel gas cutting , oxygen arc cutting , and oxygen lance cutting.
Electrolytic copper free from cuprous oxide, produced without the use of residual metallic or metalloidal deoxidizers.
Oxygen cutting in which a bevel or groove is formed.
A length of pipe used to convey oxygen either beneath or on top of the melt in a steelmaking furnace, or to the point of cutting in oxygen lance cutting.
oxygen lance cutting
An oxygen cutting process used to sever metals with oxygen supplied through a consumable lance; the preheat to start the cutting is obtained by other means.
An atmosphere-monitoring device that electronically measures the difference between the partial pressure of oxygen in a furnace or furnace supply atmosphere and the external air.