Testing corrosion fatigue

Edyvean, R. G. J., Thomas, C. J., Brook, R., and Austen, I. M., "The Use of Biologically Active Environments for Testing Corrosion Fatigue Properties of Offshore Structural Steels, Proceedings, Biologically Induced Corrosion, S. C. Dexter, Ed., NACE-8, National Association of Corrosion Engineers, Houston, TX, 1986, p. 254. 

Doyle, J. L., Wood, G. R., and Bondurant, P. D. Using Laser-Based Profilometry to Locate and Measure Corrosion Fatigue Cracking in Boiler Tubes, Materials Evaluation, D The American Society of Nondestructive Testing, Inc., Vol. 51, No. 5, pp. 556-560 (1993). 

Corrosion-fatigue cracks can be detected by nondestructive testing techniques such as magnetic particle inspection, radiography, ultrasonics, and dye penetrant. Corrosion-fatigue cracks may occur in numerous tubes simultaneously. Nondestructive testing of tubes at locations similar to those in which cracks are observed can be useftil. 

In a previous section it has already been observed that high-strength 2000 and 7000 series alloys are sensitive to the presence of water vapour in corrosion fatigue tests. Stress-corrosion susceptibilities of these alloys in low temperature aqueous solutions and the effect of composition and heat treatment have been widely investigated . It is not surprising therefore that when subjected to corrosion fatigue in similar environments, substantial environmental effects can be observed particularly at low frequencies of less than 1 Hz and AA values above These environmental effects tend to be... 

The data on which Fig. 8.74 is based are for tests carried out in carbonate well-water. McAdam made the further interesting discovery that if mild steel were tested in condenser water and a similar graph constructed, the set of contours corresponded more closely to the right-hand side of Fig. 8.74, i.e. the behaviour of mild steel in condenser water was similar to that of Monel in carbonate water. The apparent universality of this diagram is an interesting observation, but it has not provoked a basic theory of corrosion fatigue. 

Scott, P. M., Chemistry effects in corrosion fatigue , in ASTM STP 801, Corrosion fatigue mechanics, chemistry and engineering, American Society for Testing and Materials, pp. 319-345 (1983)... 

Rust, T, E. and Swaminathan, V. P, Corrosion fatigue testing of steam turbine blading alloys , EPRI Workshop on Corrosion Fatigue of Steam Turbine Blade Materials, Palo Alto, California, September 1981, Pergamon Press, (1983)... 

Fig. 13.10 Corrosion-fatigue tests specimen sprayed with 3% sodium chloride (after Fescol...

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). 

Fig. 19.24 (o) Rig for a laboratory study of the corrosion fatigue of welded joints in sea-water and (b) view of test-pieces showing welded joint (after Jarman et olP )... 

The NACE publication Corrosion Fatigue gives a comprehensive account of all aspects of the subject, and in this work a review of the application of fracture mechanics for studying the phenomenon has been presented by McEvily and Wei , whilst Kitagawa has given a detailed account of crack propagation in unnotched steel specimens. This work should be consulted for details of testing and interpretation of results. 

Warlow-Davies used a technique in which specimens were subjected to fretting corrosion and then tested in fatigue to show the effect of fretting damage in lowering resistance to fatigue. 

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