The development of a multiaxial stress rupture criterion for bolting steels using new and service aged materials

Creep rupture tests on uniaxial and notched bar specimens of a variety of geometries have been performed at 550°C, in order to understand the creep rupture behaviour of new and ex-service Durehete 1055 under multiaxial stress states. Existing finite element solutions for skeletal point steady state stresses in the notched bars were used to identify a representative rupture stress. A criterion for governing multiaxial rupture stress was established using the creep rupture data obtained. A good correlation between representative stresses evaluated using the Cane representative stress model and uniaxial stresses was produced. In all cases notch strengthening was observed.