Mechanical properties anisotropy of Ti-6Al-4V alloy fabricated by ,β forging

The anisotropy of tensile properties and fracture toughness of Ti-6Al-4V (Ti64) alloy fabricated by ,beta forging was investigated. In order to evaluate anisotropic mechanical properties, the microstructure and crystallographic texture of billets with different orientations were characterized, and the influence of sampling direction on tensile properties and fracture toughness was studied. The results reveal that the prior ,beta grains of Ti64 billet display pan-cake-type characteristics. At room temperature, the alloy is mainly composed of alpha phase, and several alpha phase variants produced by ,beta ->alpha phase transformation decrease the alpha texture intensity. The anisotropy of mechanical properties is affected by prior ,beta grain morphology and the slip activation related to alpha texture. The initiation toughness was obtained by the J-integral resistance curve method. The initiation toughness was divided into intrinsic and extrinsic toughness by calculation. The anisotropy of intrinsic toughness is mainly attributed to the size of crack tip plastic zone, which is affected by prior ,beta grain morphology. In contrast, the extrinsic toughness is affected by zigzag degree of crack, which is mainly influenced by alpha lamellae and colonies.