A Must-read For Newbies: GTAW Welding
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GTAW Welding refers to an arc that uses a metal or alloy rod with a high melting point as one pole of the power supply. During welding, the high-melting point electrode does not melt, but only serves to start and maintain the arc, and is welded under inert gas protection. welding method. Since high melting point thoriated tungsten rods or cerium tungsten rods are usually used as electrodes and argon gas is used as the shielding gas, it is also called tungsten electrode argon arc welding. During welding, an arc is generated between the tungsten electrode and the workpiece. The arc heat is used as the welding heat source. The filler metal is added and fed from the front of the tungsten electrode. Under the action of the arc heat, the workpiece and the filler metal melt and form a molten pool. It cools to form a weld.
GTAW welding is divided into manual GTAW welding and automatic GTAW welding according to different operating methods. At the same time, filler metal can be added or not added according to the thickness of the workpiece and design requirements. According to the polarity of the power supply, it can be divided into AC tungsten arc welding and DC tungsten arc welding. Since the polarity of the power supply remains unchanged, DC tungsten arc welding can maintain combustion at a lower arc voltage, so Has good stability. When welding low carbon steel, low alloy steel, stainless steel and titanium alloys, in order to avoid overheating and burning of the tungsten electrode, tungsten argon arc welding often uses the DC forward connection method for welding. When welding aluminum, magnesium and their alloys, AC power supply or DC reverse connection is used. Because when the connection is reversed or the weldment is in the negative half cycle, the large mass of argon ions violently bombards the molten pool and the surface of the weldment, which can remove the high melting point oxide film on the surface, which is beneficial to welding fusion and ensuring welding quality. This phenomenon is called “cathode “Broken” effect, and when the tungsten electrode is in the half cycle of the negative electrode, the tungsten rod cools down, which can reduce its loss