The phenomenon of stress corrosion in the austenitic chromium-nickel stainless steels is generally characterized by cracks of a transgranular branching nature. It is not so commonly known, however, that certain other kinds of localized attack also may be associated with this phenomenon and possibly may influence susceptibility.
General solubility or over-all attack usually precludes stress corrosion. This may not be the case, however, when localized types of attack are present. For example, stress corrosion and intergranular corrosion occasionally occur simultaneously; this is of unusual interest because the two can be observed individually only a few grains apart.
Figure 1 represents a cross section of a Type 316 thermocouple well which had encountered a variety of corrosive media including chlorides and sulfates. Precipitated carbides were present at the grain boundaries. It is of interest to observe the transition areas near the upper left and upper right corners of the photomicrograph, where...
