Environmental Engineering Reference
In-Depth Information
Figure 9.4
Effect of nickel content on swelling in commercial and simple Fe-15Cr-
X Ni alloys. Ref. 13
creep, radiation-enhanced creep shows a dependence on microstructure, texture,
degree of cold work, and grain size. Additionally, it exhibits a weak temperature
dependence and complex stress and flux dependencies. For a given material at
fixed temperature, flux, fluence, and plastic strain level, the components of creep
in metals before, during, and following irradiation are schematically represented
in Fig. 9.5. A normal effect of irradiation on metals is radiation hardening, which
is exhibited by an increase of yield stress, accompanied by a lower creep rate
under the same conditions than before irradiation. The postirradiated curve thus
assumes a higher position than the unirradiated curve (see Section 9.6). If various
levels of fluence are considered, a family of curves will occur progressively from
the unirradiated curve to the final or saturated postirradiated curve. The creep
rate is given by:
ε
A
σ
n
