What's Brought by Micro- and Nanoscopic Approaches to Joining & Welding Metallurgy?(Materials, Metallurgy & Weldability, INTERNATIONAL SYMPOSIUM OF JWRI 30TH ANNIVERSARY)

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Results from TEM (Transmission Electron Microscope) observations made at JWRI are introduced to exemplify nano-scale microstructures that can contribute to improving or controlling the performances of joints produced by fusion welding and solid-state bonding. For fusion welding, the microstructure of a weld metal of 950MPa class steel was investigated to determine the favorable requirements for both strength and ductility. It is concluded that a mixture of martensite and plate (plus lath) bainite is favorable and the mechanical properties are reduced by the formation of granular bainite, as the hardenability is decreased. For the friction-bonding of Al alloy to steel, it was found that reaction products forming in the interfacial region less than a few μm in width are influenced remarkably by minor alloying elements in the Al alloy, which caused a great difference in the bond strength. With respect to the anodic bonding, by which glass is bonded to metal, by taking advantage of the drift of alkali ions in the glass under an electrostatic field, the debonding phenomenon was investigated by applying an electric field opposite to that applied during bonding. It turned out that the debonding of a glass/Kovar-alloy joint was suppressed by coating the Kovar alloy surface with Al thin film. This effect of the Al coating film is explained as resulting from the properties of interfacial reaction products several 10nm in size.


  • Transactions of JWRI

    Transactions of JWRI 32(1), 107-112, 2003-07

    Osaka University


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