Spectroscopic Diagnostics of Pulsed Gas Tungsten Arc Welding Plasma and Its Effect on Weld Formation of Aluminum-Magnesium Alloy

ABSTRACT Welding arc properties have been studied by means of spectroscopic and optical techniques to optimize the effective arc heat in a pulsed gas tungsten arc welding. A spectral line fitting algorithm was developed for plasma diagnostics. The relationships among arc length, weld pool size, vaporization of weld metal associated with arc temperature, and electron density were discussed in terms of thermal equilibrium. Results showed that arc length and alloying vapor had important effects on the effective arc heat. With an increasing arc length from 2 to 4 mm, both arc temperature and electron density first increased and then decreased, showing good agreement with the weld pool width. An optimum arc length with the maximum of effective arc heat has been found, which was particular for the selected welding conditions but easy to generalize.