Welding - Chapters 1-6 - First Exam with Complete Solutions

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Welding - Chapters 1-6 - First Exam with Complete Solutions List welding Currents: AC,DC-,DC+ What is the Definition of welding current the current in the welding circuit during the making of the weld. Three units are used to measure welding current Voltage: electrical pressure Amperage: number of electrons flowing Wattage: power of the arc What approximately is The temperature of the arc? 11,000°F (6000°C). Three different types of current used for welding are Alternating Current: evenly distributed between (+) and (-) Direct-Current Electrode Positive: electrode positive, ground (work) negative Direct-Current Electrode Negative: electrode negative, ground (work) positive the voltage at the electrode before striking an arc (no current being drawn) Open-circuit voltage Operating voltage the voltage at the arc during welding Arc blow the deflection of the arc from its normal path because of magnetic forces. Duty Cycle percentage of time a welding machine can be used continuously at maximum amperage AC Alternating Current AWS stands for American Welding Society. 5 basic welding joints are lap, tee, edge, corner, butt 4 welding positions are flat, horizontal, vertical, and overhead 2 ways to strike an arc are tapping and scratching the distance the arc must jump from the end of the electrode to the plate or weld pool surface is? Arc length What Is The Measurement of the electrode to the surface of the metal? Electrode angle a straight weld with little or no side-to-side motion stringer bead A tack weld holds pieces together until final welding can take place. DC+ vs DCDC+ will mean the current flows from the electrode to the base metal. This creates more heat at the electrode which creates less penetration but results in a better deposition. DC- gives you better penetration into the base metal but less filler metal is deposited. Conventional Flow Theory Starts at the positive and flows towards the negative. This is commonly illustrated in diagrams, but is not recognized as the chosen theory. Electron Flow Theory Theory which states electrons flow from negative to positive weld "a localized coalescence (the fusion or growing together of the grain structure of the materials being welded) of metals or nonmetals produced either by heating the materials to the required welding temperatures, with or without the application of pressure, or by the application of pressure alone, and with or without the use of filler materials.". smaw Shielded metal arc welding (SMAW) - also known as "stick welding", uses an electrode that has flux, the protectant for the puddle, around it. The electrode holder holds the electrode as it slowly melts away. Slag protects the weld puddle from atmospheric contamination. gtaw Gas tungsten arc welding... TIG..heliarc...manual welding process that uses a non-consumable tungsten electrode, an inert gas, and a separate filler material. gmaw Gas metal arc welding (GMAW) - commonly termed MIG (metal, inert gas), uses a wire feeding gun that feeds wire at an adjustable speed and flows an argon-based shielding gas or a mix of argon and carbon dioxide (CO2) over the weld puddle to protect it from atmospheric contamination. FCAW Flux-cored arc welding (FCAW) forge weld the most ancient welding processes, is a solid-state welding process that joins two pieces of metal by heating them to a high temperature and then hammering them together elihu thomson inventor of arc welding in 188

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