A new creep damage assessment method for metallic material under variable load conditions at elevated temperature

摘要

It is significant for structural design and maintenance to assess behaviour and life under varying load conditions. For structures operating in high-temperature environments, creep is one mechanism responsible for material failures. In this paper, different damage accumulation rules were reviewed, and a new creep damage assessment method was proposed based on the creep damage tolerance parameter lambda and load factor phi. By introducing the creep damage tolerance parameter lambda and the minimum creep rate, the loading process and creep behaviour of the material are taken into account in a damage assessment. The parameters in the model can be obtained by the simple variable load creep test, and the remaining life and strain can be predicted using uniaxial creep test data. To analyse the applicability and accuracy of this new model, the strain histories, the life of step load, and the constant load creep from experiments on a titanium alloy at 500 degrees C were obtained, and the prediction results of the novel and previous methods were carefully investigated.