A2024アルミニウム合金板の成形性支配機構の究明

概要

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The press-forming tests of the precipitate-hardening aluminum sheet, A2024, were conducted under the various pre-aging conditions, such as quenching and full annealing, as the preliminary test of a thermomechanical treatment to aim at the coexistence of the strengthening of sheet and the improvement of the press-formability. The main results are summarized as follows : (1) This metal deforms locally and ununiformly, and then initiates shear crack without the necking. (2) In deep-drawing, three types of fractures which occurred over the flange to the wall, i.e., ""Bending and unbending-"", ""Tip-shear-"" and ""Wall-fracture"", were observed in addition to the punch-profile fracture. (3) The former three fractures are controlled by the strain accumulation in the flange, the bending on the die shoulder and anisotropy of the material, so the drawability correlates with the new measure, γcr=(1-1.5|Δr|/r^^-), where γcr is the fracture strain in the in-plane shear test, r is the normal anisotropy, Δr=r_0+r_<90>-2r_<45>)/2 and r^^-=(r_0+r_<90>+2r_<45>)/4.
1986-05-25