AWS - Chapter 3 - Gas Tungsten Arc Welding
| Organization: | AWS |
| Publication Date: | 1 January 2004 |
| Page Count: | 42 |
scope:
Gas tungsten arc welding (GTAW) is an arc welding process that uses an arc between a nonconsumable tungsten electrode and the workpiece to establish a weld pool. The process is used with shielding gas and without the application of pressure, and may be used with or without the addition of filler metal.1,2 Because of the high quality of welds that can be produced by gas tungsten arc welding, the process has become an indispensable tool for many manufacturers, including those in the aerospace, nuclear, marine, petrochemical and semiconductor industries. The possibility of using helium to shield a welding arc and weld pool was first investigated in the 1920s.3 However, there was no incentive for further development or use of this process until the beginning of World War II, when a great need emerged in the aircraft industry to replace riveting as the method for joining reactive materials, such as aluminum and magnesium. The welding industry responded by producing a stable, efficient heat source with which excellent welds could be made using a tungsten electrode and direct current arc power with the electrode negative. Helium was selected to provide the necessary shielding because it was the only inert gas readily available at the time. Tungsten electrode inert gas torches typical of that period are shown in Figure 3.1. The process has been called nonconsumable electrode welding and is very often referred to as TIG (tungsten inert gas) welding. However, because shielding gas mixtures that are not inert can be used for certain applications, the American Welding Society (AWS) adopted gas tungsten arc welding (GTAW) as the standard terminology for the process. Numerous improvements have been made to the process and equipment since the early days of the invention. Welding power sources were developed specifically for the process, some providing pulsed direct current and variable-polarity alternating current. Water-cooled and gas-cooled torches were developed. The tungsten electrodes were alloyed with small amounts of active elements to increase emissivity, thus improving arc starting, arc stability, and electrode life. Shielding gas mixtures were identified for improved welding performance. Researchers continue to pursue improvements in such areas as automatic controls, vision and penetration sensors, and arc length controls. The fundamentals of the GTAW process and a variation that uses pulsed current (GTAW-P) are discussed in this chapter, along with applications of the process, equipment and consumables used, techniques and procedures, welding variables, weld quality, and safety considerations.
abstract:
Gas Tungsten Arc Welding
Related Products
Searching for related products...