Modeling creep behaviour of boiler grade steels - Application to grade 92 steel

Abstract : Power generation is now striving to improve the global efficiency of boiler plants, targeting 50% or higher. To accommodate the necessary increase in steam temperature, new materials may be developed and/or existing materials must be employed to their best. This is mandatory for the design of boiler components. One contribution by V&M in that direction is the setting up of numerical models for major boiler grades regarding their creep resistance. In coordination with Mines ParisTech, the first application has been made to Grade 92.The methodology is presented together with the first simulations. Typically, creep is modelled using two deformation mechanisms which correspond respectively to a low stress regime and a high stress regime. Damage is also taken into account. Calculations were carried out using ABAQUS ®. Numerical results are compared with a series of creep tests performed at Vallourec Research Aulnoye (VRA). Further development and applications of the model are finally discussed.