Gas Metal Arc Weld (GMAW) Qualification of 7020-T651 Aluminum

Report No. ARL-TR-7515
Authors: John F Chinella; Nick Kapustka; Seth Shira
Date/Pages: November 2015; 94 pages
Abstract: This study determines weld joint characteristics of high-strength aluminum (Al), fusion-weld filler metals, Al-magnesium (Mg) alloys AA5087, AA5556A, and Al-Mg6-Zr fusion welded with the gas metal arc weld (GMAW) pulse (P) and spray (S) methods to AA7020-T651 Al. The study qualifies pulse and spray weld method weld joints of 25- and 40-mm-thick Al 7020-T651 plates with visual, radiographic, and metallographic examinations, and bend and tension tests. These fusion-weld filler metals and compositions have capabilities to better match the high strength levels of candidate Al structural and protection materials (e.g., Al-Zn-Mg 7020) for application to land vehicles. The 7020 alloy has demonstrated improved durability and shock resistance over the 7017 or 7039 alloys and improved yield strengths over 5083 and 6061 Al; therefore, high-strength Al, with tough, ductile, weld joints may provide improved protection and crash safety by means of a rigid vehicle structure. This investigation revealed 7020-T651 (has best tensile 43.4–46 ksi strength results) with 5087 filler and the GMAW-P-mode yield strengths of 28â??31 ksi, and elongations of 6.8%–9.4%. The 7020 alloy is recommended as "weldable" with tensile strength requirements of 43–46 ksi.
Distribution: Approved for public release
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Last Update / Reviewed: November 1, 2015