ボイラ及び圧力容器用2.25Cr-1Mo鋼の高温疲労寿命に及ぼすヒート,熱処理,ひずみ制御モードの影響

摘要

High temperature fatigue tests were conducted for normalized and tempered 2.25Cr-lMo steels of three heats. As compared with the reference data, the influence of heats, heat-treatments and testing conditions such as testing temperature, strain rate and strain control mode on the high temperature fatigue lives were investigated. The results obtained are as follows.Heats of the normalized and tempered 2.25Cr-1Mb steels scarcely affected the fatigue lives at high temperatures.Between annealed and normalized and tempered 2.25Cr-1Mo steels there was scarcely difference in the fatigue lives.Strain rate between 10~(-3) and 10~(-2)/s scarcely affected the high temperature fatigue lives of 2.25Cr-1Mo steel.Strain control mode and testing temperature affected the fatigue lives. In this case the strain control modes are axial and diametral.From these results, the ASME fatigue design curves of 2.25Cr-1Mo steel for nuclear components were unconservative for the data tested under axial strain control at each temperature. Modified design curves were proposed for normalized and tempered 2.25Cr-1 Mo steels