Gas Metal Arc Weld (GMAW) Qualification of 7020-T651 Aluminum
Final rept. 1 Sep 2014-30 Sep 2015
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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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 28-31 ksi, and elongations of 6.8-9.4. The 7020 alloy is recommended as weldable with tensile strength requirements of 43-46 ksi.
- Metallurgy and Metallography