The Effect of Nickel Content on the Stress Corrosion Resistance of Fe-Cr-Ni Alloys in an Elevated Temperature Caustic Environment Available to Purchase

Recent studies¹  of the stress corrosion behavior of Fe-Cr-Ni alloys in a deaerated 50% NaOH solution at 316 C (600 F) have shown that resistance to stress corrosion cracking (SCC) increases with increasing nickel content of the alloys. The data leading to this conclusion, which are summarized in Figure 1, were obtained using conventional U-bend specimens. There are two well recognized facts relating to the use of U-bend specimens in stress corrosion testing. First, the times-to-failure reflect the sum of the times to initiate and to propagate stress corrosion cracks, so that it is often difficult to ascertain whether the resistance of a given alloy to SCC derives from resistance to initiation, propagation or both. Secondly, U-bend specimens are generally very highly stressed. For example, for the Alloy 600 U-bend specimens used to gather the data of Figure 1, the outer fiber stress was of the order...