| As the service time of power plant approaches its design life, the crack initiation and growth in boiler components becomes major concerns. Though there are many research effort for finding out the properties of used materials with the materials artificially aged by heat treatment, the obtained results are nothing but the estimated values to be verified. In this study, characteristics of the crack growth behavior for 1Cr-0.5Mo steel which was served for a boiler header for about 30 years were studied by performing fatigue crack growth tests at 538℃ and room temperature under triangular and trapezoidal wave-shapes. In order to evaluate hold time effect at elevated temperatures, the fatigue test with 10 second hold time (0.083Hz) was performed. From the experimental results, it was found that the increase of the fatigue test temperature had a significant effect on the increase of the rate of fatigue crack propagation. In the case of hold time testing, the oxidation layer formed at the crack wake was thicker than in the case without hold time. |
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