Influences of chemical and thermal environments on delay in a Ti-6Al-4V alloy
Experiments were conducted within the framework of linear fracture mechanics to study the effects of chemical and thermal environments on crack-growth retardation (delay) in mill-annealed Ti-6Al-4V alloy under elemental load spectra. Attention is focused on the influence of hold time at high load on delay in a 3.5 percent NaCl solution at room temperature. It is shown that delay is strongly affected by hold time at high load, where delay is longest if the high-load excursion occurs at high temperature and the subsequent fatigue is at room temperature, and shortest if the temperature profile is reversed. The results suggest that residual stresses ahead of the advancing crack play an important role in delay. The significance of combined load and environment (chemical and thermal) effects in terms of modeling and life prediction procedures is discussed.