Development of Tension-Torsion Multiaxial Creep Testing Apparatus for Heat Resisting Steel

Abstract

This paper describes development of a combined tensiontorsion multiaxial creep testing apparatus for heat resisting steel. It is essential for high temperature component designing to investigate creep rupture life and creep properties of heat resisting steel. Although high temperature structural components undergo multiaxial stress damage due to complex loading situation or shape discontinuity of the actual structure, there is no commercial testing apparatus which can conduct a creep testing under multiaxial stress conditions. In this study, we developed a combined tension-torsion multiaxial creep testing apparatus which can apply multiaxial stress to a hollow cylinder type testing specimen with 6 kN axial load and 12 Nm torsional load at high temperatures. Since the testing apparatus also has measuring devices for axial and shear displacements of the specimen, relationship curve between testing time and equivalent strain under multiaxial stress conditions of type 304 stainless steel is also discussed.