THE EFFECT OF HYDROGEN CONTENT ON THE FRACTURE OF PRECRACKED TITANIUMSPECIMENS

Slow straining of compact tension specimens of Grade-2 and Grade-12 ti tanium has been developed as a means of assessing the likelihood of fa ilure in titanium containers for nuclear waste disposal. Hydrided spec imens were strained to failure and the stress intensity factors corres ponding to slow crack growth and fast brittle failure calculated. In a ll the materials tested, stable slow crack growth in the as-received m aterial was replaced by fast brittle failure at high hydrogen levels, but whether or not the latter was preceded by slow subcritical crack g rowth depended upon the hydrogen concentration, the alloy concerned an d the orientation of the applied stress with respect to preferred orie ntation in the fabricated material. The orientation of beta-phase pres ent appeared to exert a greater influence than the basal pole concentr ation on susceptibility to slow crack growth and the onset of fast bri ttle failure.