経年劣化した 2 1/4Cr-1Mo 鋳鋼のクリープき裂進展特性の評価

概要

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Creep crack growth behavior was experimentally investigated at 570℃ in 2 1/4Cr-1Mo cast steels, taken out of heavy section components in power boiler plants of which the total service life were longer than 100000 hours. Stress intensity factor, load line displacement rate, C^*-integral and Q^*-parameter were used as parameters to evaluate the creep crack growth rate. And, degradation of crack growth in aged materials was observed in the evaluations. In the relationship of C^*-integral or load line displacement rate, and the creep crack growth rate, the so-called tail part, which characterizes the early stage of the test owing to the transient behavior, was considered. The relationship between the minimum of load line displacement rate and fracture life fell on practically a single trend line in terms of Monkman-Grant type equation. It means that the equation is found to be of activation type. At last, the softening region near crack tip was discussed in the relation of the crack growth resistance.
社団法人日本鉄鋼協会の論文
1992-11-01