Multiaxial creep behavior of nickel-base heat-resistant alloys Hastelloy XR and Ni-Cr-W superalloy at elevated temperatures

ニッケル基耐熱合金ハステロイXRとNi-Cr-W合金の高温多軸クリープ挙動

加治 芳行  ; 辻 宏和; 西 宏; 武藤 康; Penkalla, H. J.*; Schubert, F.*

Kaji, Yoshiyuki; Tsuji, Hirokazu; Nishi, Hiroshi; Muto, Yasushi; Penkalla, H. J.*; Schubert, F.*

原研において、原子力用構造材料として開発したハステロイXRとNi-Cr-W合金の多軸クリープ挙動を調べ、多軸条件下での変形挙動を記述する構成式を検証するために、一連の単軸及び多軸クリープ試験を実施した。Norton型クリープ構成式とMisesの流れ則を種々の負荷条件下での多軸クリープ挙動の予測に適用した。ほとんどの場合には、これらの材料の多軸クリープ挙動は、単軸クリープ試験結果から求めたパラメータに基づく構成式によってよく記述できたが、一部例外な場合も見られた。本研究から、簡易設計法としてNorton型クリープ構成式とMisesの流れ則に基づく方法をハステロイXR及びNi-Cr-W合金の多軸クリープ挙動を記述するのに適用できることがわかった。

A series of uniaxial and multiaxial creep tests was carried out on Hastelloy XR and Ni-Cr-W superalloy, which were developed as the high temperature structural materials for nuclear application at the JAERI, in order to investigate multiaxial creep behavior of these materials and to verify the laws for the description of deformation under multiaxial loadings. Norton's creep law and von Mises' flow rule were applied to the prediction of multiaxial creep behavior of a tube under some significant loading conditions. In most cases the multiaxial creep behavior of these materials were successfully described with the constitutive equations based on the material parameters fitting uniaxial creep test results, though a few exceptional cases were observed. The present study has revealed that the method based on Norton's creep law and von Mises' flow rule are basically applicable for the description of the multiaxial creep behavior for Hastelloy XR and Ni-Cr-W superalloy as the conventional design method.