Environmental Engineering Reference
In-Depth Information
Figure 3.20
(a) Step structure from electrolytic-oxalic acid etch test in solution-an-
nealed type 304 stainless steel (400
). (b) Ditch structure in sensitized steel (400
).
creases with degree of sensitization. No such peak is observed for unsensitized
material. The difference in behavior is shown schematically in Fig. 3.21.
3.6.4 Other Alloys
Precipitation-hardenable nickel alloys like Inconel X-750 are susceptible to inter-
granular corrosion in hot caustic solutions, in boiling 75% nitric acid, and in
high-temperature water containing low concentrations of other salts. Solid solu-
tion-type alloys like Inconel 600 are also susceptible in the same media when
thermally treated in the range of 540-760
C, which gives rise to the grain bound-
ary precipitation of carbides. In Alloy C, grain boundary precipitation of molyb-
°
