Abnormal macropore formation during double-sided gas tungsten arc welding of magnesium AZ91D alloy
- College of Mechanical Engineering, Chongqing University, Chongqing 400044 (China)
- College of Material Science and Engineering, Chongqing University, Chongqing 400044 (China)
One of the major concerns during gas tungsten arc (GTA) welding of cast magnesium alloys is the presence of large macroporosity in weldments, normally thought to occur from the presence of gas in the castings. In this study, a double-sided GTA welding process was adopted to join wrought magnesium AZ91D alloy plates. Micropores were formed in the weld zone of the first side that was welded, due to precipitation of H{sub 2} as the mushy zone freezes. When the reverse side was welded, the heat generated caused the mushy zone in the initial weld to reform. The micropores in the initial weld then coalesced and expanded to form macropores by means of gas expansion through small holes that are present at the grain boundaries in the partially melted zone. Macropores in the partially melted zone increase with increased heat input, so that when a filler metal is used the macropores are smaller in number and in size.
- OSTI ID:
- 21140755
- Journal Information:
- Materials Characterization, Vol. 59, Issue 8; Other Information: DOI: 10.1016/j.matchar.2007.08.021; PII: S1044-5803(07)00311-7; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
- Country of Publication:
- United States
- Language:
- English
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