TEXTURE GRADIENT, AVERAGE TEXTURE, AND PLASTIC ANISOTROPY IN VARIOUS AL-LI SHEET ALLOYS

The variation of texture through the thickness and the average texture of sheet material of recrystallised AA 8090 and unrecrystallised AA 8 090 (crossrolled) and AA 2090 Al-Li alloys have been investigated. Con ventional (lithium free) AA 2024 alloy in the annealed condition was u sed as a reference material. The quantitative orientation distribution functions were determined via X-ray diffraction and neutron diffracti on techniques. Using X-ray diffraction, textures of layers at various distances from the surface to the centre of the sheets were examined t o achieve the texture gradients. The average textures were determined either via neutron diffraction using cylindrical stacked specimens or by summing the texture results obtained via the X-ray technique for th e various layers. It is shown that the intensity of the common rolling textures, i.e. {112}[111], {123}[634], {110}[112], and shear texture {100}[011] markedly varied through the thickness of unrecrystallised u nrecrystallised AA 8090 and AA 2090 Al-Li sheets. Also, in recrystalli sed AA 8090 Al-Li and AA 2024, a variation of the recrystallisation te xture components {001}[100] and {011}[100] through the thickness was f ound. The quantitative texture data in conjunction with Taylor theory were used to predict the plastic anisotropy in terms of the plastic st rain ratio as a function of the angle alpha between the lolling and te nsile directions. This prediction shows that the effects of texture ca n explain well the anisotropy in recrystallised Al-LI material (AA 809 0). For unrecrystallised materials (AA 8090, AA 2090), a correct trend in plastic anisotropy is predicted; however, the calculated values in the 45 degrees direction are larger than those determined experimenta lly.