The GHTA (Gas Hollow Tungsten Arc) welding, which employs hollow tungsten electrodes, was introduced as process that achieve adequate welded joint strengths in aluminium alloy butt welds and fulfill the requirements to repair components of the International Space Station (ISS). However, electromagnetic interferences might cause problems of the arc initiation. Therefore, GHTA starting experiments using the touch start technique, which lifts the electrode from the state such that the electrode and the specimen are in contact, were tested and the applicability under the ISS orbital pressure were investigated. SUS304 stainless steel and A2014-T6 aluminium alloy were employed as the base metal test specimens. The results obtained form the experiments can be summarized as follows: 1) GHTA starting by the touch start technique is feasible under ISS orbital pressure 10 (exp-5)Pa. 2) There is little difference in the GHTA starting phenomena between SUS 304 stainless steel and A2014 aluminium alloy. 3)The GTA starting phenomena and GHTA starting phenomena using the touch start technique are very similar. However, compared with GTA starting, GHTA starting has a low plasma density so the arc voltage is high and the arc discharge has a low brightness. 4) The arc starting phenomena of the touch start technique are not susceptible to be influenced by the environmental pressure or the maximum electrode gap, an electrode lifting condition, or the starting conditions such as the velocity. 5) The touch start technique is superior as an arc initiation technique in space GHTA welding for consideration to application in the ISS orbit.
Arc initiation phenomena by space GHTA welding process using touch start technique in a vacuum
Welding International ; 20 , 9 ; 707-712
2006
6 Seiten, 8 Bilder, 1 Tabelle, 14 Quellen
Article (Journal)
English
Butt Welding Joint of Aluminum Alloy by Space GHTA Welding Process in Vacuum
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