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Ray, G. P. (1983) Some aspects of crack initiation in mild steel subjected to fatigue stressing in a corrosive environment. Doctoral thesis, City of London Polytechnic.
Some aspects of the corrosion fatigue crack initiation in EN1 type mild steel have been studied.
Results of the electrochemical investigations show that the application of both static and compressive stresses enhance anodic dissolution. Application of cyclic stress assists the breakdown of the surface film resulting in localised attack,
Metallographic studies indicate that a sulphur enriched band of ferrite exists around the non-metallic inclusions and corrosion occurs in this contaminated band with and without applied stress. Cyclic stress enhances the formation and coalescence of micropits at and around the inclusions leading to the nucléation of cracks. Preferential attack also occurs at the ferrite - pearlite interfaces, at slip band - matrix interfaces, and at grain boundaries. All these modes of attack can lead to crack nucleation.
It has also been found that non-metallic inclusions can act as sites for hydrogen blisters; this may assist the nucléation of cracks.
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