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Impact Welding: Fundamental Studies on Weld Interface Structure

Lee, Taeseon
http://rave.ohiolink.edu/etdc/view?acc_num=osu1543493357444402

Abstract Details

2018, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
Impact welding is a method for joining similar and dissimilar metals by a high-speed collision. In this study, a novel impact welding technology, Vaporizing Foil Actuator Welding (VFAW), is used to investigate the process-structure-property relationship of impact welding and expand its applications. VFAW has been shown to successfully weld aluminum alloy plates of over 6 mm thickness to steel in a laboratory environment. Mechanical testing results show that the joint lap shear strength is equivalent or superior to the shear strength of the base materials. A significant portion of this work contributes to understanding of process parameter effects on the weld interface morphology. The typical wave-like interface found in impact welds regularly shows a distinctive wavelength and amplitude, and is believed to indicate a high joint strength by possible mechanical interlocking as well as metallurgical bonding. The determining factors of the wave size and shape are investigated by manipulating process parameters such as material thicknesses and collision angle. From both experimental and numerical observations, the interfacial wavelength is found to be positively correlated with both material thicknesses and collision angle, but the correlation seems to weaken when the target thickness exceeds two times the flyer thickness. The relationships are validated by robust numerical simulations using Arbitrary Lagrangian-Eulerian (ALE) and Smooth Particle Hydrodynamics (SPH) methods, performed by the project collaborators. The relationships are explained in terms of propagation and interference of shock waves at the interface. Metallurgical characteristics of the weld interface are also studied using several advanced microscopy techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron back-scattered diffraction (EBSD), X-ray micro-computed tomography (µ-CT), energy-dispersive X-ray spectroscopy (EDXS), and nano-diffraction. In this study, grain structures in and near the weld interface of pseudo single grained Cu/Cu and Cu/Ag welds are revealed. Evidence of severe plastic deformation are easily found in both micro and nano-scale observations. In close proximity to the interface a thin (~25 nm) intermixed layer along the interface is observed, where compositional analysis confirms that both elements co-exist while maintaining crystallinity. The rigorous microscopic characterization conducted in this study attempts to aid in understanding the bonding mechanism during impact welding.
Glenn Daehn (Advisor)
Michael Mills (Committee Member)
Stephen Niezgoda (Committee Member)
Brad Kinsey (Committee Member)
164 p.
Automotive Materials; Experiments; Materials Science; Mechanical Engineering; Metallurgy
Impact Welding; Interface; Metallurgy; Stress Wave; Microscopy; Dissimilar Materials

Recommended Citations

Citations

  • Lee, T. (2018). Impact Welding: Fundamental Studies on Weld Interface Structure [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543493357444402

    APA Style (7th edition)

  • Lee, Taeseon. Impact Welding: Fundamental Studies on Weld Interface Structure. 2018. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1543493357444402.

    MLA Style (8th edition)

  • Lee, Taeseon. "Impact Welding: Fundamental Studies on Weld Interface Structure." Doctoral dissertation, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543493357444402

    Chicago Manual of Style (17th edition)

osu1543493357444402
292
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This open access ETD is published by The Ohio State University and OhioLINK.