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1. What is the major function of the coating on an arc welding electrode? a. Acts as a scavenger, removes oxides and impurities b. Influences incomplete penetration c. Liquefies the base metal d. Adds moisture and accelerates the cooling rate The key is major function, and that is to purify the weld pool and weld metal. 2. Square wave refers to the ____________. a. shape of the filler metal b. shape of the tungsten electrode c. shape of the output power d. shape of the power source control box The shape of the output wave form from this type power source is referred to as square wave. These type power sources have enhanced performance on a.c. They can control the balance, amplitude, frequency etc… to allow better control of penetration and cleaning action. 3. Shielding gases are used to protect the molten metal from _______. a. being overheated and cooling to fast b. porosity and brittleness c. heat and distortion d. being too cold and not penetrating The surrounding air around the weld pool, contains oxygen, nitrogen and hydrogen. These gases get into the molten weld pool and cause gas bubbles to form (porosity) and lead to embrittlement and weld cracking. 4. Weld backing is used with a process that uses a separate flux and electrode to _______ . a. make the overall weld joint stiffer b. provide more weight to the weldment c. make the material thicker where it is needed d. support the highly fluid weld pool so it will not fall through the joint Weld backing is used on the back side of the joint to prevent melt through and to assure complete penetration of the weld joint. 5. _________ is the weight of a volume of material compared with an equal volume of water. a. Mass b. Density c. Specific gravity d. Heft
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