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Welder’s Handbook
Defect – A discontinuity or discontinuities that by nature or accumulated effected (for example total crack length) render a part or product unable to meet minimum applicable acceptance standards or specifications. The term designates rejectability. Deoxidizers – Elements, such as manganese, silicon, aluminium, titanium, and zirconium, used in welding electrodes and wires to prevent oxygen from forming harmful oxides and porosity in weld metal.
Divergency – The tapered part of the oxygen bore directly behind the throat in high pressure (high speed) nozzle designs. The divergency allows the high pressure to become close to atmospheric before it leaves the nozzle. This increases stream velocity and improves cut quality by keeping stream uniform. The increased velocity produces 10–15% higher cutting speeds. Double Arcing – A condition in which the welding or cutting arc of a plasma arc torch does not pass through the constricting orifice but transfers to the inside surface of the nozzle. A secondary arc is simultaneously established between the outside surface of the nozzle and the workpiece. Downhill – Welding with a downward progression. Drag – The offset distance between the entrance and exit points of the gas stream on the plate being cut, measured on the cut edge. Drag will increase and decrease with varying conditions such as speed, oxygen pressure, plate thickness, oxygen purity, etc.
Deposited Metal – Filler metal that has been added during welding, brazing or soldering.
Deposition Efficiency – The relationship of the electrode used to the amount of the weld metal deposited, expressed in percent, i.e.; DE = Weight of Weld Metal ÷ Weight of Electrode Used Deposition Rate – The weight of weld metal deposited compared to the time of welding. It is usually expressed in pounds per hour. Depth of Bevel – The perpendicular distance from the base metal surface to the root edge or the beginning of the root face. Depth of Fusion – The distance that fusion extends into the base metal or previous bead from the surface melted during welding. Digging – Refers to the arc characteristics that you normally see with a 6010 electrode. A “digging” arc is one in which you can see parent metal being penetrated at the arc. Dilution – The change in chemical composition of a welding filler metal caused by the admixture of the base metal or previous weld metal in the weld bead. It is measured by the percentage of base metal or previous weld metal in the weld bead. Direct Current – An electrical current which flows in only one direction in a conductor. Direction of current is dependent upon the electrical connections to the battery or other DC power source. Terminals on all DC devices are usually marked (+) or (-). Reversing the leads will reverse the direction of current flow. Discontinuity – An interruption of the typical structure of a material, such as a lack of homogeneity in its mechanical, metallurgical, or physical characteristics. A discontinuity is not necessarily a defect. Distortion – All fusion welding methods produce the weld by moving a molten pool along the weld joint. When the heated metal cools the shrinkage introduces distortion in (or a change in the shape of) the welded structure.
Drag Angle – The angle between the impinging jet stream centerline and a direction perpendicular to the plate surface.
Dross – Re-solidified molten metal and oxides adhering to the top or bottom edge during thermal cutting.
Ductility – The ability of a material to become permanently deformed without failure.
Duty Cycle – A power source specification describing the percentage of time a system can be operated at a given current level. Based on a ten-minute cycle. E Edge Preparation – The preparation of the edges of the joint members, by cutting, cleaning, plating or other means. Effective Throat – The minimum distance minus any convexity between the weld root and the face of a fillet weld. Elastic Limit – The maximum stress to which a material can be subjected without permanent deformation or failure by breaking. Elasticity – The ability of a material to return to original shape and dimensions after a deforming load has been removed. Electrical Stick-Out – In any welding process using a solid or flux cored wire, the electrical stick-out is the distance from the contact tip to the un-melted electrode end. Sometimes called the “amount of wire in resistance”. This distance influences melt-off rate, penetration, and weld bead shape.
Electrode – The plasma arc torch part from which arc current is emitted.
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