Title: Characterisation of the plasma shape of the TIG welding arc

Authors: Janos Dobranszky, Andrea Bernath, Hilda Marton

Addresses: Research Group for Metals Technology of Hungarian Academy of Sciences, Goldmann ter 3, Budapest 1111, Hungary. ' Department of Materials Science and Engineering, Budapest University of Technology and Economics, Goldmann ter 3, Budapest 1111, Hungary. ' Department of Materials Science and Engineering, Budapest University of Technology and Economics, Goldmann ter 3, Budapest 1111, Hungary

Abstract: Tungsten electrodes were prepared to analyse the plasma geometry at TIG welding. The investigated electrodes were LaO₂ and ThO₂ alloyed. Pointed and flat-tipped electrodes were ground as well. The shape of the plasma was analysed at 36 different electrodes. The plasma geometry was measured by image analysis of a lot of digital pictures. The complete and the inner part (brightest) of the plasma were checked as well. Measured values were represented as a function of taper angles. The maximal values of taper angle, at which the plasma geometry characteristics were obtained for sharpened electrodes, were 20° and 30°. The plasma-shape characteristics of red and black electrodes are running collaterally. Despite this, the characteristics of the gold electrode shift to higher taper angles caused by the higher LaO₂ content of the electrode. There was no clear correlation between the electrode taper angle and the plasma-shape characteristics for the blunt electrodes.

Keywords: TIG welding; tungsten electrodes; electrode sharpening; plasma shape; rare-earth oxides; plasma geometry.

DOI: 10.1504/IJMMP.2008.016949

International Journal of Microstructure and Materials Properties, 2008 Vol.3 No.1, pp.126 - 140

Published online: 31 Jan 2008 *

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