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

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Figure 12 shows that the thermal treatment and heat (A, B and C) significantly affect the hydrogen embrittlement in the steel in question. The crack growth rates of different kinds of heats of 20Cr2.5MoV and 10Cr2.5Mo steels (10 -7 – 10 -4 ms -1 ) in hydrogen embrittlement tests are presented in Figure 13, where the differences between different kinds of heats also become apparent.

a) b) Figure 12. Threshold stress intensities of hydrogen embrittlement with unirradiated 15CrMoV (a) and 20Cr2.5MoV (b) steels (Tvrdy et al., 1981).

A summary of K ISH -, K ISCC - and K IC values obtained by Tvrdy et al. (1981) is presented in Figure 14. The figure shows that unirradiated 15CrMoV and 20Cr2.5MoV steels have the best hydrogen embrittlement properties. The same authors attributed this to the fact that vanadium prevents the formation of molybdenum carbides and molybdenum dissolved in the matrix primarily prevents the segregation of phosphorus to the grain boundaries so that the detrimental joint action of hydrogen and phosphorus, which manifests itself as intergranular fracture, decreases.