Machine structure under elevated temperature generally causes not only static stress but multiaxial cyclic stress. It is common to be subjected cyclic stress simultaneously with mean stress. It is necessary to accumulate not only experimental data, such as creep and fatigue, but also the experiment data of fatigue-creep interaction in designing these structures. However, there are very little studies of inelastic deformation under multiaxial cyclic stresses. The purposes of this research are to obtain of the experimental data with reliability under multiaxial cyclic stresses, and to construct of the constitutive equation. It carried out a tension-torsion cyclic tests using triangular stress wave and the tension-torsion cyclic experimental result was compared with the multi-axis cyclic creep constructive equation of two internal variables at 180℃. As the result, the constitutive model and the experimentalresult are well in agreement.
