TY - JOUR A1 - Rose, Sascha A1 - Zähr, Julia A1 - Schnick, Michael A1 - Füssel, Uwe A1 - Goecke, Sven-Frithjof A1 - Hübner, Mark T1 - Arc attachments on aluminium during tungsten electrode positive polarity in TIG welding of aluminium T2 - In: Welding in the World 55 (2011) 9-10, pp 91-99 N2 - In modem AC power sources, both balance and current of EP (tungsten electrode positive) and EN (tungsten electrode negative) can be readily adjusted. According to conventional assumptions the surface of aluminium workpieces is cleaned during EP but the tungsten electrode is more heated due to electron work function. During EN the tungsten electrode cools down and the workpiece is melted. Therefore, optimal settings of the power source mostly aim for maximal penetration and minimal electrode wear. This paper presents a study of arc attachments in TIG welding on aluminium. Two different arc attachments to the cathodic workpiece could be attested with only one of them actually cleaning the surface. The first one is a spot mode (highly dynamic) that attaches to the edges of oxide layers and cracks them. The second one is also a spot mode, but it attaches to weld pools. It does not clean the surface but heats the base material intensively. Both arc attachment modes compete against each other. As a result, the cleaning area narrows with wider weld pools due to an increasing attachment to the weld pool during EP. The influences on the arc attachment to the aluminium cathode as well as the contradictions in present literature are discussed. Possible adjustments of the AC balance for optimized processes are proposed. Y1 - 2014 UR - https://opus4.kobv.de/opus4-fhbrb/frontdoor/index/index/docId/640 SN - 1878-6669 VL - 55 IS - 9-10 SP - 91 EP - 99 ER -