Development of Weld-Type Miniature Cruciform Specimen for Multiaxial Creep Testing

This study describes the development of a welded-type miniature cruciform specimen used for multiaxial creep testing of Super304H stainless steel. The geometry of the preexist miniature cruciform specimen was modified to enable biaxial creep tests using a smaller material size with the assistance of welding technology. Finite element analyses and experimental results showed that the preexist miniature specimen made by welding had a limitation of giving a dissimilar deformation between X- and Y-direction in the equi-biaxial tension creep, depending on welding material. However, in the modified miniature creep specimen, the difference in the deformation between X- and Y-directions was suppressed within 2%. Also, the variations of X- and Y-directional stresses were within ±4% in the gauge part of the modified miniature creep specimen. The new geometry of the modified miniature specimen was verified to be testable in biaxial creep experiments for Super304H stainless steel.