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

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A delayed fracture was observed at a high hydrogen content (7 ppm) when the stress was > 80% of the notch tensile strength of steel that was not hydrogen-charged, as shown in Figure 4. Broomfield (1965) did not observe any drop in the notch tensile strength nor any increase in the susceptibility to the delayed fracture on l%Cr-0.5%Mo steel. The author did, however, observe that hydrogen increases the ductile/brittle transition temperature in both irradiated and unirradiated specimens. The hydrogen has an additive effect when combined with irradiation.

Figure 4. Delayed fracture in A212B steel at a hydrogen content of 7 ppm (Rossin et al., 1966).

Brinkman and Beeston (1970) researched the hydrogen embrittlement on ASTM A302B, A542 and HY-80 steels with irradiated specimens (7 10 18 - 5 10 20 n/cm 2 , > 1 MeV, helium atmosphere, temperatures of 225 and 300°C). A decrease in ductility and tensile strength occurred when the hydrogen content increased, although not significantly if the tensile strength was below 1200 N/mm 2 and hydrogen content was 1-2 ppm. This hydrogen content caused a significant decrease in the strength when the strength level with irradiation or thermal processing was raised above this strength value (Figures 5 and 6).