Environmental Engineering Reference
In-Depth Information
Figure 9.9
Effect of neutron irradiation on the critical shear stress of copper, Ref. 10.
Figure 9.9 shows the effect of neutron irradiation on the critical shear stress of
copper single crystals. An increase in the value of the critical shear stress from
0.241 kg/mm
2
to 2 kg/mm
2
has been observed to take place with an exposure
of about 2
10
18
nvt. The rate of increase has fallen thereafter. The effect of
irradiation in copper is somewhat similar to solid solution hardening. However,
it has been estimated [24] that one interstitial atom is 40 times more effective
than a zinc atom in raising the critical shear stress.
The tensile fractographic features in type 304 tested at 370
C are shown in
Fig. 9.10 [25]. A transition from ductile to brittle fracture is evident.
In body-centered cubic metals, a ductile-to-brittle transition temperature is
encountered and irradiation results in an increase in transition temperature.
°
Figure 9.10
Tensile fractographs of type 304 stainless steel tested at 370
°
C. (a) Unir-
radiated, (b) after about 2.8
10
22
n/cm
2
, and (c) after about 10.7
10
22
n/cm
2
. Ref. 25.
