Several nickel-based superalloys have been tested for high temperature applications for use in advanced ultra-supercritical (AUSC) fossil-fired power plants through laboratory and steam loops during the last several years. These materials include Inconel 740H and Haynes 282 which are found to have superior creep strength properties and be appropriate for use in the critical high pressure and high temperature (1400°F) AUSC boiler pressure parts such as superheater outlet header. While these materials have been extensively tested for their creep properties in laboratory test specimens, a real life design application with creep constitutive models is very limited.

In this paper, development of a microstructure sensitive continuum damage mechanics (CDM) creep model for Haynes 282 base material that covers a wide range of stress levels and temperatures suitable for AUSC boiler design applications is described. Various creep mechanisms including diffusion and dislocation phenomena are included. This base material CDM model is then applied for a typical thick-walled high temperature header component and creep life assessment for the design life of the component is estimated. This analysis along with weldments and their creep properties still under development are considered crucial for identification of high creep damage regions in the component as well as proper design life assessment of the pressure parts.

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