Influence of Heats, Heat-treatments and Strain Control Mode on High Temperature Fatigue Lives of 2.25Cr-1Mo Steels for Boiler and Pressure Vessels
2004 Volume 90 Issue 10 Pages 841-845
Details
2004 Volume 90 Issue 10 Pages 841-845
High temperature fatigue tests were conducted for normalized and tempered 2.25Cr-1Mo 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.
1) Heats of the normalized and tempered 2.25Cr-1Mo steels scarcely affected the fatigue lives at high temperatures.
2) Between annealed and normalized and tempered 2.25Cr-1Mo steels there was scarcely difference in the fatigue lives.
3) Strain rate between 10-3 and 10-2/s scarcely affected the high temperature fatigue lives of 2.25Cr-1Mo steel.
4) Strain control mode and testing temperature affected the fatigue lives. In this case the strain control modes are axial and diametral.
5) 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-1Mo steels.
