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Welder’s Handbook
Pulsed Power Welding – An arc welding process variation in which the power Is cyclically programmed to pulse so that effective but short duration values of power can be utilized. Such short duration values are significantly different from the average value of power. Equivalent terms are pulsed voltage or pulsed current welding. Pulse Transfer – Mode of metal transfer somewhat between spray and short circuiting. The specific power source has built into it two output levels: a steady background level, and a high output (peak) level. The later permits the transfer of metal across the arc. This peak output is controllable between high and low values up to several hundred cycles per second. The result of such a peak output produces a spray arc below the typical transition current. Push Angle – The travel angle when the electrode is pointing in the direction of weld progression. This angle can also be used to partially define the position of guns, torches, rods and beams. Q Quench / Quenching – Process of fast-cooling metals or alloys such as steel in the process of hardening, as air quenching, oil quenching, water quenching, etc.
Reverse Polarity – Welding condition when the electrode is connected to the positive terminal and the work is connected to the negative terminal of the welding power source. Root – The narrowest point in the gap between two members to be welded, or the point in the gap furthest removed from the electrode. Usually these points are one and the same.
Root Bend Test – A test in which the weld root is on the convex surface of a specified bend radius.
Root Crack – A weld crack originating in the root bead, which is usually smaller and of higher carbon content than subsequent beads. Crack is caused by shrinkage of the hot weld metal as it cools, placing the root bead under tension.
Root Opening– The intentional gap between members to be joined to assure 100% penetration in groove type welds.
Root Pass – The initial weld bead deposited in a multi-pass weld requiring high weld integrity.
Root Penetration – The distance the weld metal extends into the joint root.
Root Radius – A nonstandard term for groove radius.
Root Reinforcement – Weld reinforcement opposite the side from which welding was done.
qualification. See preferred terms welder performance qualification and procedure qualification.
Rutile – The natural form of the mineral titanium dioxide (TiO2). S SCR Power Source – A type of power source that uses a semiconductor device known as the silicon controlled rectifier in the main power circuit. Secondary Gas – Unlike the plasma gas, the secondary gas (also referred to as shielding gas) does not pass through the orifice of the nozzle. It passes around the nozzle and forms a shield around the arc. Self-Hardening Steels – Steels that become martensitic or fully hard by air cooling from above their critical temperature or from the austenitising temperature. Self-Shielded Flux Cored Arc Welding (FCAW-S) – A flux cored arc welding process variation in which shielding gas is obtained exclusively from the flux within the electrode. Semi-Automatic Welding – Welding with a continuous solid wire or flux Cored electrode where the wire feed speed, shielding gas flow rate, and voltage are preset on the equipment, and the operator guides the hand held welding gun along the joint to be welded.
*quality control. A procedure of tests set up by shops to inspect weldments as they are produced to ensure that they meet the standards set up by the manufacturer. R Radial crack – A crack originating in the fusion zone and extending into the base metal, usually at right angles to the line of fusion. This type of crack is due to the high stresses involved in the cooling of a rigid structure. Radiographic quality – Soundness of a weld that show no internal or underbead cracks, voids or inclusions when inspected by X-ray or gamma ray techniques.
Rectifier – An electrical device used to change alternating current to direct current.
Reduced Section Tension Test – A test in which a transverse section of the weld is located in the center of the reduced section of the specimen. Residual Stresses – Internal stresses that exist in a metal at room temperature as the result of (1) previous non-uniform heating and expansion, or (2) a composite structure composed of a ductile constituent and a brittle one.
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