Doel 3 & Tihange 2 - Some Peer-reviewed Scientific Papers & Reports

Hydrogen and radiation embrittlement of RPV steels

17

20

~; ~o ~3o c

. . . . . . . . .

\

x= 290 c °

0-"=-*

L

N .

\ 1 1 8 0%

2

5 ~o 20

5o ~oo

soo

[Am-2 ]

Fig. 2.

Elongation A5 of irradiated and unirradiated CrMoV steel as a function of current density.

The hydrogen charging of specimens irradiated at 130 and 180"C, and with higher current densities, led to the superposition of hydrogen and radiation embrittlement. This was shown by the decrease of elongation and reduction in area for hydrogen contents over 8-10 ppm and current densities over 100Am -2, at which full loss of ductile behaviour of steel occurred, as was the case reported by Koutsk~, e t al . 1'2 Compar ison of the convent ional engineering load-displacement curves in a tensile test demonstrated that specimens charged at current densities of 100A m -2 fractured before the material tensile strength was reached (Fig. 3). Radiat ion embrittlement caused a decrease in the uniform elongation value which, for both hydrogen-charged and hydrogen-free specimens (at current densities up to 50A m-2), reached approximately the same value and decreased with decrease of irradiation temperature (Fig, 4). On the contrary, for the specimens irradiated at 290"C the uniform elongat ion value after hydrogen charging increased in comparison with the unirradiated specimens. The local necking elongation was affected by hydrogen content over 2.5 ppm (Fig. 5). A considerable decrease of the local necking elongation was observed above 10 A m -2 and the data plotted semilogarithmically suggested a linear relationship.