866 Modern Welding Cutting oxygen lever: Lever on an oxyfuel gas cutting torch that is depressed to control the fl ow of oxygen from the cutting oxygen orifi ce. Cutting plane line: Heavy dashed line that shows a theo- retical cut through an object. Cutting process: An action that causes separating or removal of metal. Cutting tip: The part of an oxygen cutting torch from which the gases are released. Cutting torch: The piece of equipment in a cutting outfi t that controls and directs the gases and oxygen needed for cutting and removing the metal in oxyfuel gas cutting. Cycle: A set of repeating events that occur in order. Also, one complete waveform of alternating current. Cylinder: A container holding the supply of high-pressure gas used in welding. Cylinder cap: A heavy steel safety cap that screws onto the top of the cylinder to protect the cylinder stem during movement or shipment. Cylinder gauge: A gauge attached to a gas cylinder that shows the pressure of the gas contained in the cylinder. Cylinder manifold: See Manifold. D Dash numbers: Numbers used at the end of carbon steel electrode classifi cations to indicate electrode polarity, shielding gas requirements, etc. DCEN: Direct current that fl ows from the electrode to the work. DCEP: Direct current that fl ows from the work to the electrode. DCRP: A nonstandard term. See Direct current electrode positive. DCSP: A nonstandard term. See Direct current electrode negative. Decalescence: Transformation that takes place during super- heating of iron or steel. The metal surface darkens due to the sudden decrease of temperature during the rapid absorp- tion of the latent heat of transformation. Decarburization: Carbon loss from the surface of a ferrous alloy when the alloy is heated in a medium that reacts with the surface carbon. Deep etching: The eating away (as with the corrosive action of acid) of a metal surface. This allows examining of the surface with a magnifi er to detect features such as grain fl ow, cracks, or porosity. Defect: An imperfection or fl aw which, by its size, shape, location, or makeup, makes the part unfi t for service. A defect must be repaired. Degasifi er: A substance that can be added to molten metal to draw off soluble gases before they are trapped in the metal. Degassing: Process of removing gases from liquids or solids. Degreasing: Removal of grease or oil from the surface of a metal. Degreasing solvent: A liquid that effectively dissolves grease and oil. Degree: One unit of a temperature scale. Demagnetization: Removal of existing magnetism from a part. Demurrage: Charge made by a gas supplier to the gas user as rent on the gas cylinder. Dendrite: A crystal structure with a branching pattern. Formed in cast metals as they are slowly cooled through the solidifi cation range. Denitrifi ers: Elements added to most electrode wires to reduce the porosity in the fi nished weld. Density: The mass of a substance per unit of volume. Deoxidized copper: Copper that has had a very small amount of silicon added to it, which dissolves any oxides in the metal. Deoxidizer: A substance which, when added to molten metal, removes either free or combined oxygen. Deoxidizing: Process of removing oxygen from molten metals with a deoxidizer. In metal fi nishing, removing oxide fi lms with chemicals or electrochemical processes. Deposition rate: Weight of material applied in a unit of time. Usually expressed in lbs/hr or kg/hr. Depth of bevel: The depth of preparation for beveled groove joints. Depth of fusion: Depth to which base metal is melted during welding. Destructive testing (DT): The process of testing a sample until it fails. Used to determine how large a disconti- nuity can be before it is considered a fl aw. Destructive tests: Tests that determine the physical proper- ties of a weld, but destroy the test sample in the process. Detail drawing: A drawing that shows the shape and size of each small part of an assembly. Detonation fl ame spraying: Thermal spraying process that uses controlled explosions of a mixture of fuel gas and oxygen to propel a powdered coating material onto the surface of a workpiece. Detonation fl ame spraying gun: Spray gun that contains a combustion chamber in which oxygen, a fuel gas, and a charge of surfacing materials mix. Dewar fl ask: A cylinder designed to hold gases that have been reduced in temperature until they become liquid in form. Die: A type of tool used to shape or cut metal. Die casting: Production of parts by forcing molten metal into a metal die or mold. Also, the part made by this process. Die forging: A part shaped by the use of dies in a forging operation. Diffusion: Spreading of an element throughout a gas, liquid, or solid, so that all of it has the same composition. Diode: A device used in an electrical circuit that permits electricity to fl ow in only one direction. Direct current (dc): Electric current that fl ows only in one direction. Direct current (dc) power sources: Machines that produce direct current for welding. Direct current electrode negative (DCEN): Direct current fl owing from the electrode (cathode) to the work (anode).
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