Welding Glossary D

Dash number Refers to an AWS assigned number that indicates how an flux cored arc welding (FCAW) electrode is to be used.
Dead annealed The result of heating a work-hardening metal to a red heat and immediately quenching in water.This softens the metal and renders it workable again.
Defect An imperfection that because of its size, shape, location or make-up, reduces the useful service life of a part.Problem that causes a testing failure in a weld.
Degree One unit of the temperature scale (degrees F or C).
Density The weight of a particular metal per unit volume.
Deoxidizer A substance added to molten metal to remove either free or combined oxygen.
Deoxydizing The process of removing oxygen from molten metal with a deoxidizer; in metal finishing, removing oxide films with chemical or electrochemical processes.
Deposited metal Filler metal tat has been added during a welding operation.
Deposition rate The weight of material applied in a unit of time, usually expressed in lbs./hr or kg/hr.
Depth of fusion The distance that fusion extends into the base metal from a previous pass from the surface melted during welding.
Destructive test A testing method that involves applying stress to a sample until it fails.Destructive testing is used to determine how large a discontinuity can be before it is considered a flaw or defect.
Dewar flask A pressurized container with an insulated double wall, used to store liquid oxygen.
Dimension The size information shown on a mechanical drawing of a part or assembly.
Direct Current DC- Current flowing in one direction only.
Direct Current Electrode Negative (DCEN) The direction of electrical flow through a welding circuit when the electrode lead is connected to the negative terminal and the work lead is connected to the positive terminal of a DC welding machine.
Direct Current Electrode Positive (DCEP) The direction of electrical flow through a welding circuit when the electrode lead is connected to the positive terminal and the work lead is connected to the negative terminal of a DC welding machine.
Direct polarity Same as DCEN, with the electrode negative.
Direct current reverse polarity (DCRP) Same as DCEP.
Direct current straight polarity (DCSP) Same as DCEN.
Distill To separate, by means of different boiling points, the different gases or liquids in a compound, such as air.
Distortion Warping of a metal or metal surface as a result of uneven cooling.
Downhand welding Welding in a flat position.
Downslope Refers to the downward curve of a volt-ampere graph.
Drag The offset distance between the actual and theoretical exit points of the plasma cutting stream, measured on the exit side of the material.
Drag angle The angle between the electrode and the workpiece when backhand welding.
Drag welding A welding technique where the heavy covering of a covered electrode is dragged across the surface of the workpiece to maintain a constant arc length.
Drive rolls The rolls in a wire feed drive unit that are directly driven by the unit's drive motor.The rolls perform the work of pushing the welding wire through the welding gun and through the contact tip.The rolls wear as a result of performing this work and frequently need to be replaced.
Droopers The term for constant current welding machines, also called droop curve machines because of the voltage vs. amperage curve they produce.
Drop-thru An undesirable sagging or surface irregularity, usually encountered when welding near the solidus of the base metal.The condition is caused by overheating with rapid diffusion or alloying between the filler metal and the base metal.
Ductility The property of metals that enables them to be mechanically deformed without breaking when cold.
Duty Cycle The number of minutes per 10-minute cycle that an arc welding system can operate at maximum level before needing to cool down.For example, a MIG welding system rated at 350 amps, 60% duty cycle can weld at 350 amps for six minutes and then must cool for the next four minutes before the cycle can be repeated.The lowest duty cycle component in the welding system determines the duty cycle capacity (typically either the machine or the torch).