Corrosion fatigue mechanisms of high-strength steel wires in the presence of various aggressive ions

This work focuses on the corrosion fatigue of high-strength steel wires with diameters of 200 μm. The fatigue load consists of a bending rotation with a stress amplitude between 1300 MPa and 700 MPa. Various solutions at pH 6 containing either sulfate, a mixture of citrate and either phosphate or hydroxyl are selected to evaluate the role of each ion or their combinations in accelerating the breakdown of the wires. For the higher stress amplitude applied, the lifetime is almost independent of the solution, showing mechanically controlled damage. For the lowest stress amplitude, the corrosion-fatigue limit significantly evolves depending on the solution. Sulfate leads to the shortest lifetimes, whereas experiments performed in deionized water show the longest lifetimes. A combination of citrate with either phosphate or hydroxyl leads to intermediate lifetime. The effect of each ion on the stability of the iron hydroxide oxide and the iron dissolution mechanisms is discussed. The results highlight the role of the chemical affinity of these ions with the iron surface and their consequences in corrosion fatigue crack generation.