Environmental Engineering Reference
In-Depth Information
Figure 9.6
Dose dependence of stress normalised creep strain of stainless steel [15].
The principal mechanisms of radiation-enhanced creep are as follows:
1.
Stress-induced preferred nucleation (SIPN)
2.
Stress-induced preferred absorption (SIPA)
3.
Climb-enabled glide mechanisms, and
4.
Stress-induced gas-driven mechanism
Stress-Induced Preferred Nucleation
Nucleation of planar aggregates of self-interstitial atoms on crystallographic
planes orthogonal to the externally applied stress axis would increase the length
of the body in the direction of stress, leading to creep strain. A similar effect
could be obtained by the condensation of vacancies on planes parallel to the stress
axis. In the SIPN mechanism, it is envisaged that the stress induces or enhances
such preferred nucleation of radiation-produced point defects [17].
Stress-Induced Preferred Absorption
In this mechanism [18], the irradiation creep is derived purely from the disloca-
tion climb that results from the preferred absorption of point defects. Preferential
absorption of point defects is mainly attributable to two factors: (1) the Cottrell
