The interpretation of experimental observation date for the development of mechanisms based creep damage constitutive equations for high chromium steel

It is very important to design a safe factor or estimating the remain lifetime for electric power plant components of steam pipes which mostly are manufactured from high chromium steels and work at high temperature and low stress level. The authors will develop the mechanisms based on creep damage constitutive equations for high chromium steel under lows stress in initial stage: (1) Creep cavities were mostly formed attaching with the precipitation of Laves phase or on grain boundary. The Laves phase should play an active role in the nucleation of creep cavities and suggest to explore the function between cavity nucleation and the evolution of Laves phase; (2) The dominant cavity nucleation damage mechanism controls; (3) Brittle intergranluar is fracture model; (4) High density number of cavity of crept test high chromium steel at high temperature under low stress could be as fracture criterion.