Fe-4.1at%Mo合金の高温クリープ機構

抄録

Creep characteristics of a bcc solid solution were investigated under constant stresses of 6-40MPa at 1100-1200K in an argon atmosphere. The stress exponent for the steady-state creep rate was 3.2 and the apparent activation energy was 320kJ/mol.
Creep curves were of inverse-or sigmoidal-primary types. After an increase in stress during the steadystate creep, inverse transient creep curve without instantaneous plastic srain was obtained. These results indicate that dislocations glide viscously.
Internal stress was determined by stress-transient dip test applying a back-extrapolation technique. The average internal stress during the steady-state creep was obviously smaller than the applied stress. Hence, the role of dislocations which glide viscously cannot be neglected in discussion of the steadystate creep process in this alloy under the present creep condition.
The creep characteristics were discussed in terms of the motion of dislocations which drag the Cottrell solute atmospheres, using the average effective stress and the density of dislocations within subgrains. The theoretically-expected values of the stress exponent and the apparent activation energy are in reasonable agreement with the exerimental values. The calculated value of the steady-state creep rate is about an order of magnitude smaller than the actually-observed one.