Steels_ Metallurgy and Applications, Third Edition

248 Steels: Metallurgy and Applications

1000 -

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9 High-strength 1CrMo(old)

o Low-strength 1CrMo(old)

9 34CrMo4 (1CrMo)

" Current 1CrMo

9 Experimental 1CrMo

O 35CD4 (1CrMo)

9 Experimental CMn

O 28Mn6 (CMn)

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260 270 280 290 300 310 320 330 340

Hardness, HB

Original upper

Figure 3.32 The influence of hardness on the enhancement of fatigue crack growth by
hydrogen (After Harris et al. 2])

The problem containers in the UK were manufactured in Cr-Mo steel,
which had been used for many years for the manufacture of storage containers
without any serious problems. However, the transportable hydrogen containers
differed from the storage containers in one important respect, namely the refilling
frequency, which was the main source of fatigue cycling, the other being due to