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Friction Stir Welding for Armor Applications

Lyda, Paul John, II
http://rave.ohiolink.edu/etdc/view?acc_num=osu1669139040130765

Abstract Details

2022, Master of Science, Ohio State University, Welding Engineering.
For many years, the defense industry has made large investments into making their armored combat vehicles as light as possible without compromising the security of the operators. These heavy vehicles are less agile and more expensive to operate and transport. Friction Stir Welding (FSW) offers a lightweight solution that promotes the weight reduction of these armored vehicles. Traditional arc welding processes create issues that FSW eliminates. As a solid-state process, FSW utilizes low peak temperatures during the welding process which results in superior mechanical performance due to the reduction of the heat affected zone (HAZ) and the dynamic recrystallization that occurs within the stir zone while simultaneously eliminating the potential for hot cracking and hydrogen induced cracking. The overarching goal of this work is to create welds that exceed the capabilities of current arc welding processes utilized in the armor industry. To achieve this goal, this body of work explores the utilization of various in-process thermal management techniques to improve production time and mechanical performance on High Hard Armor (HHA) Steel. This work also investigates the residual stresses present following FSW of Rolled Homogenous Armor (RHA) steel while also looking into the ballistic strength of friction stir welded RHA joints. The in-process induction heating system allowed for the welding speed to be increased by 50%. When this heating system was paired with an ancillary cooling system, the resulting process produced a non-uniform stir zone with various points of high hardness and a larger heat affected zone. Induction assisted + ancillary cooling FSW produced similar toughness values when compared to conventional FSW in all regions of the weld. Residual stresses were successfully measured utilizing neutron diffraction and align with previous research where in the transverse and normal directions high tensile residual stresses were seen in the advancing side and in the longitudinal direction high tensile stresses were observed in the HAZ. The ballistic testing conducted revealed an 8.5% reduction in ballistic strength of the welded region when compared to the military standard.
Desmond Bourgeois (Committee Member)
Antonio Ramirez (Advisor)
160 p.
Metallurgy
Friction Stir Welding, Armor Steel, Induction Heating, Ancillary Cooling, Neutron Diffraction

Recommended Citations

Citations

  • Lyda, II, P. J. (2022). Friction Stir Welding for Armor Applications [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1669139040130765

    APA Style (7th edition)

  • Lyda, II, Paul. Friction Stir Welding for Armor Applications. 2022. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1669139040130765.

    MLA Style (8th edition)

  • Lyda, II, Paul. "Friction Stir Welding for Armor Applications." Master's thesis, Ohio State University, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=osu1669139040130765

    Chicago Manual of Style (17th edition)

osu1669139040130765
112
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This open access ETD is published by The Ohio State University and OhioLINK.