Environmental Engineering Reference
In-Depth Information
Figure 8.10
SEM fractograph of embrittled 304 stainless steel exposed to high-
pressure hydrogen showing quasi-cleavage features [23].
(Fig. 8.10) observed in 304 stainless steel bears the evidence of embrittlement
due to deformation-induced martensite formation.
The mode of fracture and fractographic features associated with HSC are often
strikingly similar to those of SCC. Hydrogen-induced crack growth has been
suggested by many authors as the dominant stress corrosion mechanism for fer-
ritic steel in particular, and for metastable stainless steels, nickel-base alloys,
titanium alloys, and aluminum alloys. However, there are certain distinguishing
features between the two cracking processes:
1.
The ''specific ion'' effect that characterizes SCC is absent in HSC.
2.
The application of cathodic potential or current, which retards or stops SCC,
enhances the intensity of HSC.
