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CREEP‐FATIGUE CRACK GROWTH BEHAVIOR IN 1Cr‐1Mo‐0.25V STEELS. PART I: ESTIMATION OF CRACK TIP PARAMETERS
Author(s) -
Adefris N.,
Saxena A.,
McDowell D. L.
Publication year - 1996
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.1996.tb00976.x
Subject(s) - creep , materials science , finite element method , work (physics) , structural engineering , deformation (meteorology) , paris' law , composite material , metallurgy , fracture mechanics , crack closure , engineering , mechanical engineering
— Non‐linear finite element (FEM) analyses, involving various creep deformation laws, as well as experiments with hold times of 100 s and 15 min were performed on compact type specimens with stationary cracks. The work was aimed at developing accurate expressions for estimating the small‐scale creep parameters, ( C t ) avg , for 1Cr‐1Mo‐0.25V steel at 538°C (1000°F). Here ( C t ) avg is a representative value for the small‐scale creep parameter C t , averaged over a hold period under the conditions of creep‐fatigue loading. These expressions were then applied to crack growth data obtained from specimens tested under the various hold times. When an elastic‐plastic‐primary creep‐secondary creep constitutive model was used in the FEM analyses, the calculated values of C t compared well with the measured values. The FEM results also showed that the accumulated creep deformation during the hold time was not significantly reversed during the unloading portion of the creep‐fatigue cycle for this material. Therefore, a new method of estimating (C t ) avg is proposed on the basis of these numerical and experimental results.