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In true corrosion fatigue, the fatigue-crack-growth rate is enhanced by corrosion; this effect is seen in all three regions of the fatigue-crack growth-rate diagram. The diagram on the left is a schematic of crack-growth rate under true corrosion fatigue; the curve shifts to a lower stress-intensity-factor range in the corrosive environment.
WEC initiation at MnS inclusions in steel [1]. White etching cracks (WEC), or white structure flaking or brittle flaking, is a type of rolling contact fatigue (RCF) damage that can occur in bearing steels under certain conditions, such as hydrogen embrittlement, high stress, inadequate lubrication, and high temperature.
Fatigue has traditionally been associated with the failure of metal components which led to the term metal fatigue. In the nineteenth century, the sudden failing of metal railway axles was thought to be caused by the metal crystallising because of the brittle appearance of the fracture surface, but this has since been disproved. [ 1 ]
Diffusion-controlled leaching (ion exchange) is characteristic of the initial phase of corrosion and involves replacement of alkali ions in the glass by a hydronium (H 3 O +) ion from the solution. It causes an ion-selective depletion of near surface layers of glasses and gives an inverse-square-root dependence of corrosion rate with exposure time.
The crack is expected to propagate when the strain energy release rate exceeds a critical value - called the critical strain energy release rate. The fracture toughness and the critical strain energy release rate for plane stress are related by
The hole drilling method is a method for measuring residual stresses, [1] [2] in a material. Residual stress occurs in a material in the absence of external loads. Residual stress interacts with the applied loading on the material to affect the overall strength, fatigue, and corrosion performance of the material.
It could have been corrosion, it could have been a fire. Any leakage of water coming through to the electrics could lead to failure as well,” he told the paper.
Possible mechanisms for breach of containment, shown to the left, include structural degradation (abrasion, corrosion, fatigue), spurious pressurization above design limits, inadvertent opening, etc. Shown to the right of the central event, are the results/outcomes of the release (e.g., noise, blast overpressure propagation, flying debris, loss ...