Friction Stir Dovetailing of AA7099 to Steel with AA6061 Interlayer for Reduced Zn Embrittlement at Dissimilar Interface

Journal Article · Mon Jan 04 04:00:00 EST 2021 · Journal of Manufacturing Processes

DOI:https://doi.org/10.1016/j.jmapro.2020.10.084· OSTI ID:1721679

Reza E Rabby, MD ^[1]; Olszta, Matthew J. ^[1]; Overman, Nicole R. ^[1]; Mcdonnell, Martin ^[2]; Whalen, Scott A. ^[1]

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1. BATTELLE (PACIFIC NW LAB)
2. U.S. Army Tank Automotive Research, Development and Engineering Center

Joining of high strength Al alloy (AA7099) to steel (rolled homogeneous armor) with and without AA6061 interlayer was achieved using a friction stir dovetailing (FSD) method. Detailed investigations were conducted to establish correlations between mechanical performance and microstructural evolution of FSD joints. Lap shear tensile testing revealed that incorporation of the AA6061 interlayer combined with tailored processing methodology significantly improved both mechanical interlocking and load transmission across the dovetail interface. Following incorporation of the interlayer, the maximum load carrying capacity and peak extension (of the AA7099/AA6061/steel joint) are 60% and 210% higher, respectively, than results obtained from an AA7099/steel joint without an interlayer. Without an AA6061 interlayer, formation of zinc rich intermetallic compounds led to brittle interfacial failure of the AA7099-steel FSD joint. Incorporation of novel tool and joint configuration eliminated asymmetric joint performance as a function of loading direction, which is generally observed in friction stir lap welding. The efficacy of the use of an AA6061 interlayer in joining AA7099 to steel was demonstrated through mechanical testing as well as high resolution analytical electron microscopy characterization.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1721679
• Report Number(s): PNNL-SA-155326
• Journal Information: Journal of Manufacturing Processes, Journal Name: Journal of Manufacturing Processes Vol. 61
• Country of Publication: United States
• Language: English

Related Subjects

Dissimilar metal joining
Friction stir dovetailing
Aluminum
AA7099
AA6061
Rolled homogeneous armor