Optical Diagnostics for Metallurgical Processes.

Abstract

Many industrially important metallurgical processes are accompanied by the emission of light, the analysis of which often supplies useful information concerning the current state of the process while also providing insight into the details of specific process mechanisms. Optical diagnostic techniques are finding an increasingly wide range of application throughout the metallurgical community. This paper discusses the application of emission spectroscopy and imaging techniques to the analysis of such diverse processes as vacuum arc remelting, laser welding, and arc welding. A discussion of these techniques will be presented addressing such subjects as instrumentation, data analysis, the kind of information available and its potential impact on the selection of process parameters. Special attention will be given to discussing the difficulties encountered in applying these diagnostic technologies to “real life” processes in non-laboratory environments.

Plasma diagnostic by emission spectroscopy during vacuum arc remelting

“…As a comparison, the distribution temperature values measured by Williamson et al [4] for nickel base alloy electrodes and a current density of about 10 5 A m −2 are in the range of 0.5-0.6 eV and equal to 1 eV for the atoms and the singly charged ions, respectively. Our measurements for similar current densities (column 1 in table 3) are in agreement with those values.…”

“…The configuration of a VAR furnace makes experimental investigations of the electric arc itself difficult to be carried out and there is therefore little coverage of such investigations 0963-0252/02/030301+08$30.00 © 2002 IOP Publishing Ltd Printed in the UK in the literature. The experimental knowledge of the arc behaviour is mainly based on the series of investigations published by Zanner and co-workers from the 1980s, which involve nickel base alloy and special steel electrodes [1][2][3][4].…”