Creep, Damage and Life Prediction for High Temperature Materials

摘要

The high temperature static failure mechanisms of several representativesuperalloys (Inconel 718, 800 and 783) were studied under controlled loading and environmental conditions. As part of this experimental program, high temperature Digital Image Correlation was applied to measure local deformation fields of fracture mechanics specimens. The measured deformations were compared to those predicted by various creep fracture theories and by finite element models. Such comparisons, combined with metallographic and fractographic evidence, support the theory that the micromechanisms of failure are strongly influenced by the occurrence of stress accelerated grain boundary oxygen embrittlement. Consequently, a constitutive model that describes the combined effects of creep damage and oxygen embrittlement for superalloys at elevated temperatures and under oxidizing environments has been developed.