Modelling high temperature creep of Cr---Mo steel

A computer based design aid called CRISPEN using established physical models of creep deformation has been developed jointly by NPL Teddington and Cambridge University for creep strain prediction of engineering alloys. This has been used to successfully predict the creep behaviour of a range of superalloys where strain softening is the most dominant mechanism of creep deformation. The present work examines how this approach could be modified to include the effect of softening due to time dependent particle coarsening, which is the most dominant mechanism of creep deformation in Cr---Mo steel. A computer program has been developed to analyse creep curves to extract the relevant constants. A large volume of existing database on 2.25 Cr---1Mo steel has been used to validate the approach. The physical significance of the parameters used has been analysed to identify the nature of stress dependence of particle coarsening behaviour in these steels.