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Title: Ion emission intensity ratios as a function of electrode gap, melting current, and pressure during low current vacuum arc remelting

Abstract

The arc energy distribution in the electrode gap plays a central role in the vacuum arc remelting (VAR) process. However, very little has been done to investigate the response of this important process variable to changes in process parameters. Emission spectroscopy was used to investigate variations in arc energy in the annulus of a VAR furnace during melting of 0.43 m diameter Alloy 718 electrode into 0.51 in diameter ingot. Time averaged (1 second) intensity data from various chromium atom and ion (Cr{sup +}) emission lines were simultaneously collected and selected intensity ratios were subsequently used as air energy indicators. These studies were carried out as a function of melting current, electrode gap, and CO partial pressure. The data were modeled and the ion electronic energy was found to be a function of electrode gap, the energy content of the ionic vapor decreasing with increasing gap length; the ion ratios were not found to be sensitive to pressure. On the other hand, the chromium atom electronic energy was difficult to model in the factor space investigated, but was determined to be sensitive, to pressure. The difference in character of the chromium ion and atom energy fluctuations in the furnace annulusmore » are attributed to the difference in the origins of these arc species and the non-equilibrium nature of the metal vapor arc. Most of the ion population is emitted directly from cathode spots, whereas much of the atomic vapor arises due to vaporization from the electrode and pool surfaces. Also, the positively charged ionic species interact more strongly with the electron gas than the neutral atomic species, the two distributions never equilibrating due to the low pressure.« less

Authors:
 [1];  [2]
  1. Sandia National Labs., Albuquerque, NM (United States)
  2. Inco Alloys International, Inc., Huntington, WV (United States)
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10176642
Report Number(s):
SAND-94-1674C; CONF-940978-3
ON: DE94017407; BR: GB0103012
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: Symposium on liquid metal processing and casting,Santa Fe, NM (United States),11-14 Sep 1994; Other Information: PBD: [1994]
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 42 ENGINEERING; ION EMISSION; EMISSION SPECTROSCOPY; VACUUM MELTING; ARC FURNACES; ELECTRODES; EMISSION SPECTRA; CHROMIUM IONS; PRESSURE DEPENDENCE; 664200; 420200; SPECTRA OF ATOMS AND MOLECULES AND THEIR INTERACTIONS WITH PHOTONS; FACILITIES, EQUIPMENT, AND TECHNIQUES

Citation Formats

Williamson, R L, and Grose, S M. Ion emission intensity ratios as a function of electrode gap, melting current, and pressure during low current vacuum arc remelting. United States: N. p., 1994. Web.
Williamson, R L, & Grose, S M. Ion emission intensity ratios as a function of electrode gap, melting current, and pressure during low current vacuum arc remelting. United States.
Williamson, R L, and Grose, S M. 1994. "Ion emission intensity ratios as a function of electrode gap, melting current, and pressure during low current vacuum arc remelting". United States. https://www.osti.gov/servlets/purl/10176642.
@article{osti_10176642,
title = {Ion emission intensity ratios as a function of electrode gap, melting current, and pressure during low current vacuum arc remelting},
author = {Williamson, R L and Grose, S M},
abstractNote = {The arc energy distribution in the electrode gap plays a central role in the vacuum arc remelting (VAR) process. However, very little has been done to investigate the response of this important process variable to changes in process parameters. Emission spectroscopy was used to investigate variations in arc energy in the annulus of a VAR furnace during melting of 0.43 m diameter Alloy 718 electrode into 0.51 in diameter ingot. Time averaged (1 second) intensity data from various chromium atom and ion (Cr{sup +}) emission lines were simultaneously collected and selected intensity ratios were subsequently used as air energy indicators. These studies were carried out as a function of melting current, electrode gap, and CO partial pressure. The data were modeled and the ion electronic energy was found to be a function of electrode gap, the energy content of the ionic vapor decreasing with increasing gap length; the ion ratios were not found to be sensitive to pressure. On the other hand, the chromium atom electronic energy was difficult to model in the factor space investigated, but was determined to be sensitive, to pressure. The difference in character of the chromium ion and atom energy fluctuations in the furnace annulus are attributed to the difference in the origins of these arc species and the non-equilibrium nature of the metal vapor arc. Most of the ion population is emitted directly from cathode spots, whereas much of the atomic vapor arises due to vaporization from the electrode and pool surfaces. Also, the positively charged ionic species interact more strongly with the electron gas than the neutral atomic species, the two distributions never equilibrating due to the low pressure.},
doi = {},
url = {https://www.osti.gov/biblio/10176642}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1994},
month = {8}
}

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