D

=WELDING GLOSSARY=


 * Defect ** - A discontinuity or discontinuities, which by nature or accumulated effect (for example, total crack length) render a part or product unable to meet minimum applicable acceptance standards or specifications. This term designates rejectability. See discontinuity and flaw. **(2) Defect** - One or more discontinuities that cause a testing failure in a weld.


 * Defective Weld ** - A defective weld is a weld containing one or more defect. ** (2) Defective Weld ** - A weld with one or more of the following defects: Porosity, undercut, slag inclusion and improper weld size.


 * Deposited Metal ** - Filler metal that has been added during a welding operation.


 * Deposition efficiency (arc welding) - ** The ratio of the weight of deposited metal to the net weight of filler metal consumed, exclusive of stubs.


 * Depth of fusion - ** The distance that fusion extends into the base metal or previous pass from the surface melted during welding.


 * Dig ** - Also called Arc Control. Gives a power source variable additional amperage during low voltage (short arc length) conditions while welding. Helps avoid “sticking” [|Stick] electrodes when a short arc length is used.


 * Dilution ** - The change in chemical composition of a welding filler material caused by the admixture of the base material or previously deposited weld material in the deposited weld bead. Dilution is normally measured by the percentage of base material or previously deposited weld material in the weld bead.


 * Direct Current (DC) ** - Flows in one direction and does not reverse its direction of flow as does alternating current. Direct Current Electrode Positive (DCEP) - The direction of current flow through a welding circuit when the electrode lead is connected to a positive terminal and the work lead is connected to a negative terminal to a DC welding machine. Also called direct current, reverse polarity (DCRP). (2) ** Direct Current (DC) ** – Or “continuous current", s considered as the constant flow of electrons in the single direction from low to high potential.


 * Direct Current Electrode Negative ** - The arrangement of direct current arc welding leads in which the work is the positive pole and the electrode is the negative pole of the welding arc. See also straight polarity. **(2) Direct Current Electrode Negative (DCEN)** - The direction of current 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. Also called direct current, straight polarity (DCSP).


 * Direct Current Electrode Positive ** . The arrangement of direct current arc welding leads in, which the work is the negative pole and the electrode, is the positive pole of the welding arc. See also reverse polarity.


 * Direct Current Reverse Polarity (DCRP) - ** See reverse polarity and direct current electrode positive.


 * Direct Current Straight Polarity (DCSP) - ** See straight polarity and direct current electrode negative.


 * Discontinuity ** - An interruption of the typical structure of a weldment, such as a lack of homogeneity in the mechanical, metallurgical, or physical characteristics of the material or weldment. A discontinuity is not necessarily a defect. See defect, flaw.


 * Double-Welded Joint ** - In arc and oxy-fuel gas welding, any joint welded from both sides.


 * Down Hand Weld ** - A vertical weld where the welder starts at the top and works downward.


 * Drag Angle ** . The travel angle when the electrode is pointing backward. See also backhand welding. Note: This angle can be used to define the position of welding guns, welding torches, high energy beams, welding rods, thermal cutting and thermal spraying guns.


 * Drill Press** - A drill press is a machine tool, which is for drilling holes.


 * Drop-Thru ** - An undesirable sagging or surface irregularity, usually encountered when brazing or welding near the solidus of the base metal caused by overheating with rapid diffusion or alloying between the filler metal and the base metal. drum. A filler metal package type consisting of a continuous length of electrode wound or coiled within an enclosed cylindrical container.


 * Duty Cycle ** - The percentage of time during an arbitrary test period, usually 10 minutes, during, which a power supply can be operated at its rated output without overloading. (2) ** Duty Cycle ** - The number of minutes out of a 10-minute time period an arc welding machine can be operated at maximum rated output. An example would be 60% duty cycle at 300 amps. This would mean that at 300 amps the welding machine can be used for 6 minutes and then must be allowed to cool with the fan motor running for 4 minutes.

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