Tensile and Fracture Properties of Commercially Pure Titanium (CP-70) Hemispherical Forgings

Commercially pure (CP-70) titanium is used as the metallic liner for composite overwrapped pressure vessels used in satellite launch vehicles. The metallic liner is fabricated from domes machined out of CP-70 titanium forgings. During the hot closed-die forging of CP-70 domes from billets, the amount of deformation varies location to location, due to the non-uniform flow of material in the die cavity. This non-uniform strain distribution in the hemispherical dome results in microstructural variations along the forging axis which will remain even after annealing. The aim of the present work is to study the tensile properties, impact strength and fracture toughness of CP-70 hemispherical forging in annealed condition from top end to bottom end of domes in radial and circumferential directions with a view to understand the variation in mechanical properties to asses the design margin. Study revealed significant amount of the work-hardening difference within a forged dome even after annealing.