Al-Li系合金8090厚板の二段時効による破壊じん性の改善

概要

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The short-transverse fracture toughness behavior of aluminum-lithium alloy 8090 plate was investigated by using a CNSB (chevron notched short bar) specimen. The fracture toughness K_<QVM> was reduced with a progress of the first-step aging. The double-aged (DA) alloy, which was subjected to the initial underaging (UA2) at 433K followed by the second-step aging at a higher temperature for a short time, exhibited a fairly improved K_<QVM> and a superior strength-toughness balance in comparison with the single-aged alloy, good enough to satisfy the toughness requirement in aircraft design, K_<QVM>/σ_<ys>≩2.5√<mm> where σ_<ys> is yield strength. The increase in toughness by DA treatment is attributed to the relaxation of intense slips due to dissolution of shearable σ' phase and growth of σ'-PFZ width, leading to the inhibition of intergranular fracture.
社団法人日本材料学会の論文
1996-06-15