Effect of texture components on plastic anisotropy and formability of aluminium alloy sheets

摘要

Plastic anisotropy of the typical preferred orientations appearing in textured aluminium alloy sheetshas been analyzed on the basis of the continuum mechanics of textured polycrystals (CMTP)anisotropic yield function proposed by Jonas et al. In addition, in-plane plastic anisotropy ofdifferently textured aluminium alloy sheets has been predicted and compared with the experimentalresults. Three components of {011}<112>, {123}<634> and {112}<111>, which are the mainconponents of retained texture, display the short and thick yield loci in the RD-TD orthogonalcoordinates and slender ones in the coordinates rotated by 45° form the rolling direction in thesheet plane. Corresponding to the yield loci, each of the retained texture gives a peak of R value aboveunity in the neighborhood of 45° from the rolling direction and R values that equal to or less thanunity at 0 and 90°. In contrast with the reatined texture components, a typical recrystallizationtexture, {001}<100> cube component reveals the same yield locus as the von Mises' criterion in theRD-TD coordinates and circle-like one in the 45-l35° coordinates. Cube texture gives the minimumR value of zero at 45° and the maximum one equal to unity at 0 and 90°. Either the reatinedtexture or cube texture causes large plastic anisotropy in the sheet plane and is unfavourable to deepdrawing. However, if the retained texture components and cube texture are appropriately mixed,they can counter the in-plane anisotropy of each other and realize in-plane plastic isotropy, leading tothe improvement of drawability. Both the analytical and experimental results indicate that cubetexture has a beneficial effect on the drawability of sheets, rather than being an unfavorablecomponent.