The creep-damage constitutive and life predictive model for nickel-base single-crystal superalloys

A two-state-variable creep-damage constitutive and life predictive model that has been built is discussed in this article. The cavitation-controlled damage mechanism and microstructural deg-radation, i.e., material damage mechanism, are considered. The latter is derived mainly from the rafting and derafting of the precipitate γ′. The model has been verified by the creep ex-periments of nickel-base single-crystal DD3 at 760 °C and 850 °C. The steady creep and tertiary creep can be predicted satisfactorily. The active slip systems are confirmed as octahedral 〈112〉 {111} based on the lattice rotation. The parameter C reflecting material damage mechanism depends on the crystallographic orientation and can be assigned to the value C _〈001〉 ^α along 〈001〉 crystallographic orientation and C _〈011〉 ^α along 〈011〉 orientation partially. The life in different crystallographic orientations can be predicted satisfactorily.