An accelerating thermal aging model of RAFM steel: Strategy to save time and cost of thermal aging experiment

Abstract Thermal aging experiment is an effective method to evaluate the thermostability of structure materials which serve in high temperatures. But it difficult to acquire the aging data throughout service term, because it would take a long time. Hence, an accelerating thermal aging model of China low activation martensitic (CLAM) steel was built in this paper to shorten the time of the thermal aging experiment. The microstructure analysis and Charpy impact tests were conducted on CLAM steel after thermal aging with different temperatures. The results showed that raising temperature could accelerate the grain coarsening process and the main factor of ductile-to-brittle transition temperature (DBTT) increasing was grain coarsening after aging for less than 8000 h which were analyzed by fracture model. Hence, the activation energy of grain coarsening with a value of 47.4 kJ/mol could be regarded as the activation energy of thermal aging. Then a model of accelerating thermal aging was built by using Arrhenius formula to evaluate the properties degradation during thermal aging. This strategy could be used to accelerate thermal aging process of CLAM steel through raising aging temperature and it could save time and cost for aging experiment.