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The effect of impurity gasses on variable polarity plasma arc welded 2219 aluminumVariable polarity plasma arc (VPPA) welding has been used with considerable success by NASA for the welds on the Space Shuttle External Tank as well as by others concerned with high quality welded structures. The effects of gaseous contaminants on the appearance of VPPA welds on 2219 aluminum are examined so that a welder can recognize that such contamination is present and take corrective measures. There are many possible sources of such contamination including, contaminated gas bottles, leaks in the gas plumbing, inadequate shield gas flow, condensed moisture in the gas lines or torch body, or excessive contaminants on the workpiece. The gasses chosen for study in the program were nitrogen, oxygen, methane, and hydrogen. Welds were made in a carefully controlled environment and comparisons were made between welds with various levels of these contaminants and welds made with research purity (99.9999 percent) gasses. Photographs of the weld front and backside as well as polished and etched cross sections are presented.
Document ID
19900017619
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Mcclure, John C.
(Texas Univ. El Paso, TX, United States)
Torres, Martin R.
(Texas Univ. El Paso, TX, United States)
Gurevitch, Alan C.
(Texas Univ. El Paso, TX, United States)
Newman, Robert A.
(Texas Univ. El Paso, TX, United States)
Date Acquired
September 6, 2013
Publication Date
August 31, 1989
Subject Category
Metallic Materials
Report/Patent Number
NASA-CR-183803
NAS 1.26:183803
Accession Number
90N26935
Funding Number(s)
CONTRACT_GRANT: NAS8-37425
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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