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

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

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.