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|   Arc Welding Illustrations  Arc welding, fundamentally, is a process of fusing two or more pieces of metal together to form one piece. Heating adjacent surfaces to the melting point with an electric arc and then adding a sufficient amount of molten metal to provide reinforcement and fill any vacant space between the parts to be joined accomplishes this. The series of sketches below shows this arc welding process. Some knowledge of what takes place within this arc, shown in the illustration above, is necessary to learn how to weld successfully.      The arc is created when an electric current, regulated by a welding transformer, flows across an air gap between an electrode and the work to be welded. The intense heat generated by this arc is ideally suited for welding as it can be directed to affect only the part of the metal to be welded. To assure uniform heat from the arc, its length must be kept the same for a give rod size and current setting.
The instant the arc is struck, a part of the base metal directly beneath is melted, resulting in a small pool of molten metal, some of which is forced out by the blast of the arc and deposited along the path of the weld. The depth of the crater thus formed is the distance the weld will extend into the base metal and is referred to as the penetration of the weld.
During this transfer of metal from the weld a part of the flux coating burns off and forms a gaseous smoke screen that completely envelops the arc, protecting the molten metal from the harmful effects of oxygen and nitrogen in the surrounding atmosphere. The remainder of the flux coating that melts is carried to the molten pool where it mixes with the metal to combine with various impurities. It then floats to the surfaces to form a coating of slag which covers the deposited weld metal, protecting it from the atmosphere and retarding its cooling.
   This page was last modified on Wednesday, August 18, 2010 | |
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