Hydrogen-induced blistering

Hydrogen-induced blistering Also commonly referred to as hydrogen-induced cracking (HIC), it occurs in lower-strength (unhardened) steels, typically with tensile strengths less than about 550 MPa (80 ksi). Line pipe steels used in sour gas environments are susceptible to HIC. 

Hydrogenic ion-induced blistering has been observed, but by itself will not likely present a problem to the first wall at elevated reactor operating temperatures. The effects of blistering at high primary fluxes such as those found at beam dumps and components of neutral beam injectors, divertor throats and bombardment plates, are not known. 

Figure 6.64 Hydrogen-induced cracking (a) centreline cracks and (b) blister crack1...

Figure 1.21 Hydrogen-induced o acking (a) centerline cracks and (b) blister crack. (Figure originally published in Reference 104. Reproduced with permission of the Canadian Institute of Mining, MetaUurgy and Petroleum, www.cim.org.)...

Blisters are a form of HIC in which the buildup of hydrogen gas pressure at the initiated cracks or preexisting laminations results in localized deformation and bulging of the steel to the closest surface. High hydrogen pressures occur in blisters. Blisters occur when the hydrogen-induced crack is unable to propagate and is unable to link up with HIC on adjacent planes in the steel. 

Fig. 8.15 Hydrogen-induced cracking initiate along the wall of a hydrogen blister ABCD [72].

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