アルミニウム合金A2024-T_6の多軸塑性挙動に及ぼす時効時間の影響

概要

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Multiaxial stress tests were carried out on thin-walled cylindrical specimens of the A2024-T_6 aluminum alloys strengthened by two different precipitates. One of the A2024-T_6 alloys has the (GP[1]+GPB) structure obtained by aging for 10 min at 200℃; the other has the (θ'+S') structure obtained by prolonged aging of 5.5 hr at 200℃. The effect of aging time was examined by comparing two types of plastic deformation behavior. From the proportional combined loading tests of axial load, internal pressure and torsion, it was found tht the flow stresses changed with a rotation of the principal stress axes and a difference arose between the directions of the principal stress and principal strain increment. Under tension-internal pressure and tension-torsion, the equi-strain surfaces and strain behavior were also determined. Both alloys exhibited axisymmetric anisotropy. The degree of anisotropy was larger in the 2024-T_6 (10 min) than in the 2024-T_6 (5.5 hr). In addition, the plastic deformation behavior could be expressed precisely by the constitutive equation derived from the proposed yield function, hardening law and associated flow rule.
1993-05-15