Multiaxial creep damage and lifetime evaluation under biaxial and triaxial stresses for type 304 stainless steel

Biaxial, triaxial and uniaxial tension creep tests were performed using 304 stainless steel using biaxial and triaxial creep machines, and creep void formation and creep rupture lifetimes were observed. Raised creep void formation was found in biaxial and triaxial stress states than in uniaxial stress state. Clear void formation was confirmed under the equi-triaxial stress state, which demonstrated that von Mises equivalent stress was not essentially a suitable measure to evaluate creep damage and rupture lifetime in multiaxial stress states. A new equivalent stress taking account of the stress multiaxiality was proposed based on the multiaxial creep rupture data obtained in this study.