Stress corrosion cracking accelerating ions

Heterogeneities associated with a metal have been classified in Table 1.1 as atomic see Fig. 1.1), microscopic (visible under an optical microscope), and macroscopic, and their effects are considered in various sections of the present work. It is relevant to observe, however, that the detailed mechanism of all aspects of corrosion, e.g. the passage of a metallic cation from the lattice to the solution, specific effects of ions and species in solution in accelerating or inhibiting corrosion or causing stress-corrosion cracking, etc. must involve a consideration of the detailed atomic structure of the metal or alloy. 

HalicteSCC of Ti-811 in methanol accelerates with halo-gen/halide additions. Water additions have an in-hibitive effect, and numerous species have been found that inhibit transgrantilar (Stage II) stress cracking in methanol depending on halide level. These include nitrate and sulfate ions, NaF, and O.IM concentrations of Al, Zr" ", Cd , and Sn" " metallic ions Corrosion, Vol 27,1971, p 46-48). Investigators have also demonstrated that titanium alloy SCC in neutral methanol/halide solutions can be fully arrested by appHed cathodic potentials of—1.0 to —1.5 V (SCE). 

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