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

Available online: 31 Jan 2008 *

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