球形ロケットチャンバ用チタン合金の破壊靭性値とAcoustic Emission

概要

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Acoustic emission technique was applied to fracture toughness testing in Ti-6Al-4V alloys to detect crack growth. The results are as follows: (1) From the analysis of acoustic emission signals, two characteristic points (A and B points) were found. The first A-point corresponds to the initiation of slow crack growth, and the second B-point the initial deviation of crack opening displacement. These results were also verified by the observation with microscope and crack gauge. (2) The load of A-point was almost 60%of maximum load and that of B-point was 80-90%, while the load of K_<IC> value was 93-95% of maximum load. These results suggest that acoustic emission technique is a most sensitive one to detect slow crack growth. (3) There exists planer anisotropy in this alloy. J_<IC> value defined by A point had the anisotropy, which corresponds to the inclination of COD_<crit>, but not to that of K_<IC>.
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