Corrosion fatigue cracking crack initiation

Duquette, D.J., Corrosion Fatigue Crack Initiation Processes A State-of-The-Art Review, in Environment-Induced Cracking of Metals, R.P. Gangloff, M.B. Yves (eds.), NACE-10, Houston, TX, p. 45, 1990. 

Kondo, Y., and Wei, R. P., Approach On Quantitative Evaluation of Corrosion Fatigue Crack Initiation Condition, in International Conference on Evaluation of Materials Performance in Severe Environments, EVALMAT 89, Vol. 1, Kobe, Japan, November 20-23... 

Figure 2 Corrosion fatigue crack initiation by pitting corrosion (a) Schematic representation of a curve, (b) Comparison of experimentally and theoretically derived fatigue lives for the 20Cr-Ni-Mo alloy in 30 g/L NaCl solutions [8],...

The vahdity of the current ASME III code for corrosion fatigue crack initiation in low-alloy and carbon steels in LWR environments is under crrrrent review [119]. Although the model development actions are still in a preliminary stage, it is apparent that the cycles to crack irritiation (Aj) are predictable and that the conditions imder which the ASME III design curve is nonconservative can be defined (Fig. 25). 

Theories of Corrosion Fatigue Crack Initiation and Propagation... 

Giordani, E. J., Guimaraes, V. A., Pinto, T. B. and Ferreira, I. (2004), Effect of precipitates on the corrosion-fatigue crack initiation of ISO 5832-9 stainless steel biomaterial , IntemationalJoumal of Fatigue, 26,1129-36. 

Separate the metal from the environment with a physical barrier. Many corrosion inhibitors make use of this principal to protect metals. Proper use of an appropriate inhibitor may reduce or eliminate pitting. Pits are frequently initiation sites for corrosion-fatigue cracks. The effectiveness of inhibitors depends upon their application to clean metal surfaces. An example of this method is the use of zinc coatings on steel to stifle pit formation. 

Lindley, T. C., McIntyre, P. and Trant, P. J., Fatigue crack initiation at corrosion pits . Metals Technology 9, 135-42 (1982)... 

It is often difficult to conduct laboratory tests in which both the environmental and stressing conditions approximate to those encountered in service. This applies particularly to the corrosive conditions, since it is necessary to find a means of applying cyclic stresses that will also permit maintenance around the stressed areas of a corrosive environment in which the factors that influence the initiation and growth of corrosion fatigue cracks may be controlled. Among these factors are electrolyte species and concentration, temperature, pressure, pH, flow rate, dissolved oxygen content and potential (free corrosion potential or applied). 

In aluminum alloys exposed to aqueous chloride solutions, corrosion fatigue cracks frequently originate at sites of pitting or intergranular corrosion. Initial crack propagation... 

CF cracks are always initiated at the surface, unless there are near-surface defects that act as stress concentration sites and facilitate subsurface crack initiation. Crack initiation takes place independently of fatigue limit in air as it can be decreased or eliminated through the increase of dissolution rates at anodic sites. Localized corrosion such as pitting favors fatigue crack initiation through stress concentration and a local acidic environment. The two main mechanisms of CF are anodic slip dissolution and HE (80). 

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