A. Ravindra et al., ELECTRON-BEAM WELD MICROSTRUCTURES AND PROPERTIES OF ALUMINUM-LITHIUMALLOY-8090, Journal of Materials Science, 28(12), 1993, pp. 3173-3182
Lithium-containing aluminium alloys are of considerable current intere
st in the aerospace and aircraft industries because lithium additions
to aluminium improve the modulus and decrease the density compared to
conventional aluminium alloys. Few commercial aluminium-lithium alloys
have emerged for use in the aerospace industry. One such candidate is
8090, a precipitation-hardenable Al-Li-Cu-Mg alloy. The influence of
electron-beam welding on the microstructure and mechanical properties
of alloy 8090 material has been evaluated through microscopical observ
ations and mechanical tests. Microscopic observations of the electron-
beam welds revealed an absence of microporosity and hot cracking, but
revealed presence of microporosity in the transverse section of the we
ld. Mechanical tests revealed the electron-beam weld to have lower str
ength, elongation and joint efficiency. A change in microscopic fractu
re mode was observed for the welded material when compared to the unwe
lded counterpart. An attempt is made to rationalize the behaviour in t
erms of competing mechanistic effects involving the grain structure of
the material, the role of matrix deformation characteristics, grain-b
oundary chemistry and grain-boundary failure.