Characteristics of sustained-load cracking and hydrogen effects in Ti-6AI-4V

Sustained-load cracking (SLC) characteristics of Ti-6A1-4V are significantly influenced by 1) exposure temperature, 2) hydrogen content, and 3) basal plane crystallographic texture. The stress intensity applied to precracked specimens did not play a major role in affecting crack initiation or crack growth rate except that there would appear to be a required minimum level. Increasing hydrogen content raises the temperature at which SLC occurs and increases crack growth rate. A model for SLC has been proposed based on hydride precipitation at the crack tip and subsequent crack propagation by creep, cleavage, andJor interfacial separation at the hydrideJmatrix interface. Formerly with the Boeing Commercial Airplane Co., is presently an Engineering Consultant.