Relation Between Concentration of Salt Water and Corrosion Fatigue Strength on 0.37 Percent Carbon Structural Steel

The corrosion fatigue properties of 0.37 percent carbon structural steel (AISI 1035) were studied in salt water having concentrations from 0 wt percent (ion exchanged water) to 10 wt percent. The fatigue strength (at 10⁷ cycles) decreased linearly with logarithmic increase in concentration between 0.005 wt and 3 wt percent. The reduction in fatigue strength is possibly due to a wide separation of individual corroded areas by the high electrical conductivity of salt water. The fatigue strength in low concentration salt water (less than 0.005 wt percent) is almost the same as that in ion exchanged water. This may be because, in water of poor conductivity, a large number of small cracks were initiated and some of them were joined with each other.