skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Partially melted zone in aluminum welds -- Liquation mechanism and directional solidification

Abstract

Aluminum Alloy 2219 was welded by gas metal arc welding and the microstructure was examined in the partially melted zone (PMZ), which is a narrow region immediately outside the fusion zone. Extensive liquation was observed at three different locations: at large {theta} (Al{sub 2}Cu) particles, along grain boundaries (GBs) and at numerous isolated points within grains. Liquation was initiated at the eutectic temperature T{sub E}, by the eutectic reaction {alpha} + {theta} {r_arrow} L{sub E} and intensified by further melting, above T{sub E}, of the {alpha} matrix surrounding the eutectic liquid (L{sub E}). The microstructure of the liquated-and-solidified GB material is intriguing. First, the material consisted of a new GB of mostly thin, divorced eutectic and a eutectic-free strip of {alpha} immediately next to it. Second, within an individual grain, the strip was along the top and the side facing the weld. Third, with respect to the weld, the strip was always behind the new GB. These three characteristics point to an important phenomenon, that is, solidification of the liquated GB is directional - upward and toward the weld, as a result of the temperature gradients across the PMZ. A thin, brittle eutectic GB and a soft ductile {alpha} stripmore » side by side are expected to be much weaker than a normal GB before welding.« less

Authors:
;
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (US)
OSTI Identifier:
20030396
Alternate Identifier(s):
OSTI ID: 20030396
Resource Type:
Journal Article
Journal Name:
Welding Journal (Miami)
Additional Journal Information:
Journal Volume: 79; Journal Issue: 5; Other Information: PBD: May 2000; Journal ID: ISSN 0043-2296
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; GAS METAL-ARC WELDING; MICROSTRUCTURE; HEAT AFFECTED ZONE; SOLIDIFICATION

Citation Formats

Huang, C., and Kou, S. Partially melted zone in aluminum welds -- Liquation mechanism and directional solidification. United States: N. p., 2000. Web.
Huang, C., & Kou, S. Partially melted zone in aluminum welds -- Liquation mechanism and directional solidification. United States.
Huang, C., and Kou, S. Mon . "Partially melted zone in aluminum welds -- Liquation mechanism and directional solidification". United States.
@article{osti_20030396,
title = {Partially melted zone in aluminum welds -- Liquation mechanism and directional solidification},
author = {Huang, C. and Kou, S.},
abstractNote = {Aluminum Alloy 2219 was welded by gas metal arc welding and the microstructure was examined in the partially melted zone (PMZ), which is a narrow region immediately outside the fusion zone. Extensive liquation was observed at three different locations: at large {theta} (Al{sub 2}Cu) particles, along grain boundaries (GBs) and at numerous isolated points within grains. Liquation was initiated at the eutectic temperature T{sub E}, by the eutectic reaction {alpha} + {theta} {r_arrow} L{sub E} and intensified by further melting, above T{sub E}, of the {alpha} matrix surrounding the eutectic liquid (L{sub E}). The microstructure of the liquated-and-solidified GB material is intriguing. First, the material consisted of a new GB of mostly thin, divorced eutectic and a eutectic-free strip of {alpha} immediately next to it. Second, within an individual grain, the strip was along the top and the side facing the weld. Third, with respect to the weld, the strip was always behind the new GB. These three characteristics point to an important phenomenon, that is, solidification of the liquated GB is directional - upward and toward the weld, as a result of the temperature gradients across the PMZ. A thin, brittle eutectic GB and a soft ductile {alpha} strip side by side are expected to be much weaker than a normal GB before welding.},
doi = {},
journal = {Welding Journal (Miami)},
issn = {0043-2296},
number = 5,
volume = 79,
place = {United States},
year = {2000},
month = {5}
}