Some Observations Pertaining to Simple Fracture Toughness Screening Tests for Titanium.

While the KIc value of a material is a very useful measure of fracture toughness, its valid experimental determination can be a complex and expensive procedure, not at present suited to routine alloy screening or quality control purposes. To explore the feasibility of estimating KIc in titanium alloys using techniques that are more convenient to perform, impact and slow-bend tests were made on wither V-notched or fatigue-precracked Charpy specimens, and the resulting energy values were compared with the corresponding approximate KIc values. Results from five titanium-based alloys and two steels showed that precracked specimens broken in slow bend gave energy values that could be related to KIc in a straightforward manner. The best correlation between energy and KIc came from specimens having mostly flat fractures, but in the higher toughness cases, where shear lips of an appreciable size were formed, just as reasonable a relationship between energy and KIc was observed when flat fracture energies were used. Author