Cyclic creep behaviour and strain classification of a bainite 2.25Cr-1Mo
steel at 455oC
Abstract
Uniaxial static and cyclic creep tests are carried out on a bainite
2.25Cr-1Mo steel at 455°C. The dependence of cyclic response on varied
unloading conditions is investigated, with unloading rates from 0.6
MPa/s to 39 MPa/s and the valley stress duration from 0 to 30 min. A
systematic classification of strain components under cyclic creep is
proposed to determine the actual damage. The results indicate that, the
fracture modes under static and cyclic creep conditions both have
ductile features. Due to the effect of anelastic strain recovery, the
strain accumulation rate under cyclic creep is significantly retarded as
compared with static creep, and the unloading conditions apparently
influence the behaviour of anelastic strain recovery. Moreover, a life
prediction method for cyclic creep tests based on mean actual strain
deducted recovery strain is proposed.