A summary of some pertinent previous research by
other authors is presented separately from the actual
laboratory report. The report presents the results of air
and corrosion fatigue tests which are. interpreted in terms
of time to failure, crack growth history, and fracture
mechanics techniques. In addition, the results of cathodic
protection of corrosion fatigue tests are interpreted in
terms of simple-design criteria, as well as relative to
Critical Corrosion Rate Theory. One of the more significant
results presented is the greater longevity of corrosion
fatigue, as compared to air fatigue, notched specimens
stressed within 10-15 KSI above the air endurance limit.
Also, the potential required to cathodically protect such
notched specimens is shown to be 50 mV lower than for
comparable smooth specimens. Both phenomena are attributed
in part to the lowering of crack pH to acidic levels in
notched specimens.