報告書番号

Q08003

タイトル（和文）

次世代火力発電用候補材料Alloy 263の高温強度特性評価 -第１報：次世代火力の想定条件下における強度データの整備およびクリープ疲労特性の把握-

タイトル（英文）

High Temperature strength evaluation of an advanced USC candidate material Alloy 263 (1st report: Evaluation of creep-fatigue properties, and collection of basic strength data under the envisioned condition for advanced USC)

概要 （図表や脚注は「報告書全文」に掲載しております）

厚肉部材へのニッケル基超合金Alloy263の適用性を確かめるため，クリープ，疲労，クリープ疲労試験を実施した．損傷過程を明らかにするため電子線後方散乱(EBSD)による観察を行った．単純時効および疲労条件では結晶粒内の局所方位変化が見られない（１度以下）が，クリープ条件下では方位が一結晶粒内で不均質に変化し(5度程度)，結晶粒相互の拘束により微視的には不均質な変形を生じていることが伺えた．クリープ疲労では特に，粒界近傍で局所的な変化（２０度）が観察され，粒界でひずみの集中があることが示唆された．クリープ疲労破壊過程の詳細観察により，微視的に不均質な結晶粒の変形が，粒界型き裂の発生に重要な役割を果たしていることが明らかになった．

概要 （英文）

In order to verify the applicability of a Nickel-based superalloy, Alloy 263, for thick components, a series of creep, fatigue and creep-fatigue experiments were carried out. The specimens were observed using electron back scattering diffraction (EBSD) to clarify the detailed damage process. While the aged and fatigued specimens showed no remarkable local change in orientation of grains (less than 1 deg), the crept specimens exhibited inhomogeneous change of crystallographic orientation, at most 5 degrees, inside the grains. This suggests that the creep strain is inhomogeneously distributed in the grains due to the effect of the relative constraint among the grains. The creep-fatigued specimens exhibited similar local inhomogenieties in the strain distributions near the center of the grains. However, the creep-fatigued specimens showed remarkable local changes in orientation of up to 20 degrees at the vicinity of grain boundaries, indicating the occurrence of high strain concentration. A continuous observation of inhomogeneous grain deformation and damage evolution process under the load controlled creep-fatigue condition revealed that the crystallographical inhomogeneity plays a important role in evolution of strain and grain boundary damage.

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