No abstract

Uniaxial static and cyclic creep tests were carried out on bainite 2.25Cr-1Mo steel at 455 °C. Effects of the unloading rate from 0.6 to 39 MPa/s and valley stress duration from 0 to 30 min on the cyclic creep deformation behavior were discussed. The results indicated that the fracture behavior under static and cyclic creep conditions showed a consistent ductile mode. The strain accumulation rate under cyclic creep was significantly retarded as compared with static creep due to the presence of anelastic recovery which was apparently influenced by the unloading conditions. For cyclic creep tests, the unrecoverable strain component determined by a systematic classification of the stress–strain curve was the true damage. A modified life prediction method proposed based on the unrecoverable strain component presented a good life prediction for cyclic creep.

No 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.

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. Fracture surfaces of each specimen are analysed by using a scanning electron microscopy, and 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.