Investigation of texture and fracture toughness in AA 7050 plate

Aluminum alloy 7050 was rolled using an experimental regime designed to vary texture development at the T/4 (quarter-) plane. Samples of 5″ gauge plate were finished-processed to a T7451 temper. Samples were prepared for evaluation of plane strain fracture toughness (K_Ic) using compact specimens. Tests were carried out with normal to the crack in the transverse direction (T-L) as well as in the longitudinal direction (L-T). Experimental pole figures were measured and quantitative texture analysis was performed to develop the orientation distribution function. Yield surfaces were derived for each sample using polycrystal plasticity theory. Metrics developed through the quantitative texture analysis demonstrated a correlation with the difference in fracture toughness measured in the T-L and L-T samples. Specifically, the difference in the L-T and T-L fracture toughness was related to the ratio of the 111 and 100 intensities, read from the center of the corresponding pole figures. As such, the texture is providing a marker for the process history and resulting directionality in toughness response.