Feasibility analysis of damage assessment with the CRT method

The feasibility of damage assessment by CRT (creep-relaxation test) method was investigated. Four samples with different damage states were selected from creep data. ZD and ZCRT were proposed to describe the deviation caused by damage in creep and CRT respectively and their linear relationship shows that CRT is practicable and has the same effect as creep in damage assessment. PCRT and Pmin are the parameters obtained by normalizing the CRT data and creep data by the ε˙-T parameter method, respectively. PCRT-C represents PCRT under the same damage state and stress as Pmin according to the regression curves. The linear relationship between the minimum creep rate ε˙min and the CRT’ s creep rate ε˙CRT was obtained from the relationship between Pmin and PCRT-C, so that the creep rupture life can be predicted. Thus, the CRT model can save a lot of samples in damage assessment and life prediction with high accuracy, so it can reduce damage to the original components, making it more suitable for sampling small volumes of materials. Furthermore, different damage states have the same mechanism of dislocation motion during stress relaxation and creep according to activation energies and volumes, and thus the CRT method and creep exhibit similar responses to differences in material damage states due to the consistency of dislocation thermal activation motion.