Effect of plasma heat source characteristics on nitrogen absorption in gas tungsten arc weld metalReport as inadecuate




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Welding in the World

, Volume 57, Issue 6, pp 925–932

First Online: 26 July 2013Received: 20 October 2012Accepted: 23 April 2013

Abstract

Effects of plasma heat source characteristics on nitrogen absorption in gas tungsten arc GTA weld metal was investigated using two-dimensional spectroscopic measurements and numerical analyses. In the condition of 1 % nitrogen-mixed shielding gas, nitrogen content of weld metal in a helium arc or an argon-hydrogen arc decreased compared to that of an argon arc. These changes in nitrogen content had a strong correlation with arc voltages for the respective shielding gases, so it was considered that nitrogen absorption in weld metal was affected by arc plasma heat source characteristics. The spectroscopic measurements of these arcs showed that the plasma temperature near the molten pool surface in the helium arc or the argon-hydrogen arc indicated around 6,500 K, while the plasma temperature in the argon arc achieved more than 10,000 K. Additionally, from numerical analyses of GTA dealing with metal vapor, it was found that the plasma temperature in the helium arc was reduced by the metal vapor generated from the molten pool. As a result, the reduction of nitrogen disassociation caused by decreasing plasma temperature was considered as the significant factor in lowering nitrogen absorption in the helium arc.

KeywordsGTA welding Arc welding Nitrogen Absorption Shielding gases Spectroscopy Simulating Doc. IIW-2376, recommended for publication by Study Group SG-212 -The Physics of Welding-.

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Author: S. Kodama - K. Sugiura - S. Nakanishi - Y. Tsujimur - M. Tanaka - A. B. Murphy

Source: https://link.springer.com/







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