Abstract
To understand the microfracture process, Acoustic Emission three dimensional location, Acoustic Emission source characterization and fractography method have been applied for fracture toughness testing of acicular α structure in Ti-6Al-4V alloy. In this fracture process, quas-cleavage microcracks of about 200 μm diameter were nucleated at the pre-fatigue crack tip along crack front, of which distribution in the direction normal to fracture surface was about Δz=1.2 mm. Main crack growth is related to the condition where the coalescence of these microcracks occurs through specimen thickness. From these results, fracture toughness KIC and crack tip opening displacement CTODC were evaluated quantitatively, using ductile fracture criterion, and it could be concluded that these microcrackings enhance the fracture toughness of acicular α-Ti alloy.
