Corrosion fatigue prevention

Several approaches to corrosion fatigue prevention exist. On one hand, we can take measures to reduce the rate of corrosion by some of the techniques discussed in Chapter 17—for example, apply protective surface coatings, select a more corrosion-resistant material, and reduce the corrosiveness of the environment. On the other hand, it might be advisable to take actions to minimize the probability of normal fatigue failure, as outlined previously—for example, reduce the applied tensile stress level and impose residual compressive stresses on the surface of the member. 

Corrosion fatigue, therefore, is a special case of stress-corrosion cracking and fatigue failure. Figure 4-451 shows an example of pipe failures due to corrosion fatigue. Corrosion fatigue can be prevented or reduced by ... 

Effect on corrosion fatigue The combination of corrosion and fatigue can cause rapid failure, and a coating of nickel, by preventing corrosion, can increase the life of the parts. Figure 13.10 shows results obtained by the National Physical Laboratory on mild steel Wohler specimens sprayed with... 

Prevention of corrosion fatigue. One or a combination of the following procedures is recommended to prevent corrosion fatigue ... 

Galvanized coatings can stop corrosion fatigue by preventing contact of the corrosive substances with the base metal. Zinc, which is anodic to the base metal, provides electrochemical protection after the mechanical protection has ceased. 

The aim of the protective measures is to prevent corrosion fatigue cracks firom initiating rather than stopping them from propagation once they have been initiated. 

Such inhibitors act by forming protective films on the surface of the metal being subjected to corrosion fatigue. The selection of a right inhibitor and its effective concentration is important for prevention of corrosion fatigue. The price is very expensive as large amounts of inhibitors are required. 

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