Effect of corrosive environments on the fatigue strength of eutectoid steel wires

The fatigue strength of eutectoid steel wires was investigated by rotating bending tests under various corrosive environments. The high cycle fatigue strength was remarkably lower in air at relative humidity of 70% as compared with those at 30 to 50% and even in distilled water. Although the strength in NaCl aqueous solution was lower than that in distilled water, no appreciable difference was found among the NaCl solution with concentration of 1% and 0.1% and also in the solution analogous to that in the tire absorbed solution. Although the effect of dissolved oxygen concentration in the tire absorbed solution on the fatigue strength was small, that, of the hydrogen ion concentration was large in the region of PH7 to 10, slightly smaller at pH2 and no effect at pH12. Fractographic observations revealed that pitting corrosion is dominant in pH7 to 10, while the general corrosion is dominant in pH2.