Ti-6Al-4V 合金の靱性とミクロ組織因子(<特集>チタンおよびチタン合金)

概要

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Instrumented Charpy impact test, dynamic fracture toughness test and static fracture toughness test by DC electrical potential method were carried out on Ti-6Al-4V alloys with various microstructures to investigate the effect of microstructural factors including fractographic measurements on various toughness criteria, i.e., Charpy absorbed energy (E_t : total absorbed energy, E_t : apparent crack initiation energy, E_p : apparent crack propagation energy), dynamic fracture toughness (J_d), static fracture toughness (J_<IC> or K_Q), static crack propagation resistance curve (J_Rcurve), and static tearing modulus (T_<mat>). Evaluated toughness of Ti-6Al-4V alloy appeared different between Charpy test and dynamic toughness test mainly because the microstructural unit which controls the fracture may be different between these tests. Evaluated toughness by J_R curve or T_<mat> did not necessarily coincide with that by J_<IC>. Thus, it is necessary to use a proper toughness criterion according to the method of design. It was found that microstructure had a more significant role in influencing the T_<mat> rather than J_<IC>. Further, the relationships between microstructural factors, i.e., areal fraction of primary α, mean free path of primary α, depth of dimples, prior β grain size, and block size, and various toughness criteria mentioned above are clearly defined.
社団法人日本鉄鋼協会の論文
1986-04-01