Life extrapolation method based on creep curves for 12Crl MoV heat resistant steel

摘要

This paper studied the creep curves of 12CrlMoV heat resistant steel served as main steam pipes in power plants. By making a comparison between constant-stress creep and constant load creep, it was found that the θ Projection concept could describe constant stress creep successfully, but not applicable for constant load creep. A modified θ method based on the characteristic creep of 12CrlMoV steel has been developed which could both describe the constant-stress creep and constant load creep successfully. So extrapolations of creep curve were made effectively with a lot of tested data of constant load. Furthermore, through damage mechanics and normalization analysis, a new extrapolation concept step by step on basis of creep curve was put forward to assess the residual life of high temperature components in power plants. The new life extrapolation method step by step gives a more accurate creep life estimation of the considered components without considering uncertainties of classical extrapolations under the conditions such as variations in operation, changed micro structure, difference between the test specimen and the real components and so on.