2-DIMENSIONAL SECTIONS OF THE YIELD LOCUS OF A TI-6-PERCENT-AL-4-PERCENT-V ALLOY WITH A STRONG TRANSVERSE-TYPE CRYSTALLOGRAPHIC ALPHA-TEXTURE

Results obtained from mechanical tests on a Ti-6%Al-4%V sheet alloy we re used to obtain the biaxial normal stress and the in-plane simple sh ear flow stress sections of its yield locus. The critical resolved she ar stress (CRSS) of the different activated slip systems is derived fr om these experimental results of mechanical tests combined with micros tructural observations. A strong asymmetry of the CRSS and some influe nce on it of the hydrostatic stress state was found for pyramidal (c a) systems, i.e. a deviation from the Schmid law. Owing to the high s harpness of the texture in this alloy, a quasi-single-crystal approxim ation of the plastic anisotropy on the rolling plane (RP) and of the y ield locus sections measured was made. The good agreement between the simulated and the experimental results encourages the use of the propo sed CRSS values for a simulation of polycrystalline texture developmen t and yield locus derivation.