B-19 多軸応力下におけるニッケル基単結晶超合金の低サイクル疲労寿命評価(材料II,一般講演)

概要

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Multiaxial low cycle fatigue life of YH61 nickel base single crystal superalloy was investigated. Strain controlled tension-torsion combined fatigue tests were carried out at 1173K using YH61 hollow cylinder specimens of which the specimen axis was <001> crystallographic direction. The deformation behavior of the single crystal superalloy was quite different in comparison with polycrystalline alloys due to the anisotropy. A large stress and inelastic strain ranges were observed in torsional fatigue tests and their behavior could not be expressed by Mises equivalent stress and strain. Therefore, a large scatter was obtained in the correlation of multiaxial low cycle fatigue lives with Mises equivalent strain range that has been conventionally used to fatigue life assessment in multiaxial conditions. A new strain parameter, taking the anisotropy of elastic constants and inelastic strain range into account was proposed, and the parameter estimated the multiaxial low cycle fatigue lives with a reasonable scatter.
公益社団法人日本ガスタービン学会の論文
2008-10-01