Textures in Aluminum and Titanium: Their On-Line Evaluation and Quantitative Effects on Formability.

摘要

The main findings of this project were as follows: (1) For samples of an AA5xxx aluminum alloy sheet at temperatures up to 750 deg F, the degree of recrystallization could be monitored by using either resonance-EMAT spectroscopy or laser-ultrasound resonance spectroscopy. (2) Formulae showing explicitly the effects of crystallographic texture on the planar plastic anisotropy of sheets of cubic (e.g., aluminum) and of hexagonal (e.g., titanium) metals in uniaxial tension tests were derived. (3) A constitutive relation pertaining to acousto- elasticity was formulated for prestressed, orthorhombic aggregates of cubic crystallites. (4) For vertically-heterogeneous, prestressed orthorhombic media where the principal stress directions agree with the axes of orthorhombic material symmetry, a high-frequency asymptotic formula was derived which relate the depth variations of stress and texture to the dispersion of surface acoustic waves propagating in a symmetry direction.