Prediction of crack growth in CrMoV cast steel after long-term service at high temperature

A simplified prediction method is presented that uses fracture mechanics parameters for displacement-controlled conditions, which had been proposed by the authors. This method was applied to the CrMoV cast steel taken from a power plant that was in service as a main steam valve for 155,000 h at 811 K under 216 start-stop cycles. The possibility of predicting the stress–strain behavior of the long-term-served material was examined by considering the inelastic strain and thermal aging history of the material. Crack growth tests were also carried out with structural model specimens taken from the above component, and the crack growth behavior was predicted using the proposed method. Comparison with the test results showed that the proposed method was successfully applied to the prediction of the crack growth behavior of the long-term-served material.