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Examination of the physical processes associated with the keyhole region of variable polarity plasma arc welds in aluminum alloy 2219The morphology and properties of the Variable Polarity Plasma Arc (VPPA) weld composite zone are intimately related to the physical processes associated with the keyhole. This study examined the effects of oxide, halide, and sulfate additions to the weld plate on the keyhole and the weld pool. Changes in both the arc plasma character and the bead morphology were correlated to the chemical environment of the weld. Pool behavior was observed by adding flow markers to actual VPPA welds. A low temperature analog to the welding process was developed. The results of the study indicate that oxygen, even at low partial pressures, can disrupt the stable keyhole and weld pool. The results also indicate that the Marangoni surface tension driven flows dominate the weld pool over the range of welding currents studied.
Document ID
19880006252
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Walsh, Daniel W. (California Polytechnic State Univ. San Luis Obispo, CA, United States)
Date Acquired
September 5, 2013
Publication Date
November 1, 1987
Publication Information
Publication: NASA. Marshall Space Flight Center, Research Reports: 1987 NASA(ASEE Summer Faculty Fellowship Program
Subject Category
Mechanical Engineering
Accession Number
88N15634
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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