Spectroscopic studies of GTA welding plasmas. Temperature calculation and dilution measurement

¹ LEMTA, Université Henri Poincaré, B.P. 239, 54506 Vandœuvre-lès-Nancy Cedex, France
² FRAMATOME, Centre Technique, Z.I.P. Sud, B.P. 13, 71380 St. Marcel Cedex, France

Corresponding author: dlacroix@lemta.sciences.u-nancy.fr

Received: 11 March 1999
Revised: 7 July 1999
Accepted: 29 July 1999
Published online: 15 October 1999

Abstract

A spectroscopic study of the GTAW plasma-plume created during the welding of stainless steel and other materials (iron, nickel and chromium) has been carried out. The spectra of these plasmas have been studied for several welding parameters. Temperature calculations are based on the observation of relative intensities and shapes of the emission peaks. We assume that the plasma is in local thermal equilibrium. The temperature is calculated with the Boltzmann plot method from twelve iron emission lines (in the range 368–385 nm): it varies between 9650 and 12100 K. Dilution experiments have been carried out. We checked the mixing of metals: during welding of two different metallic plates and during welding with an Inconel wire. Dilution is monitored following the intensity of some characteristic emission lines (chromium and nickel). Comparison of spectroscopic results and metallographic ones is made.