Tests of pure titanium sheet (JIS # 1, 0.5mm thick) subject to biaxial stress were carried out in order to elucidate the anisotropic plastic deformation behavior for linear stress paths. Contours of plastic work and the directions of plastic strain rates at different levels of plastic work were observed in the first, second and fourth quadrants of stress space. Since the maximum equivalent strain obtainable using cruciform specimens is limited to 0.005, combined tension-internal pressure tests were carried out in order to achieve a maximum equivalent plastic strain of 0.085. These tests used tubular specimens made with a single lot of test material. Additionally, in-plane tension-compression tests were performed to observe the strength differential for the lot of pure titanium sheet between tension and compression. Using the observed data, the applicability of conventional anisotropic yield functions, such as Hill's quadratic function, the Yld 2000-2d function and Cazacu's function, to the accurate prediction of the plastic deformation behavior of the pure titanium is discussed. The measured work contours and the directions of plastic strain rates were in fair agreement with those calculated using the Yld 2000-2d and Cazacu's yield function. However, the differential work hardening behavior of the pure titanium sheet could not be accurately reproduced using these functions.
