Stainless steels corrosion fatigue

Amzallag, C., P. Rabbe, and A. Desestret (1978). Corrosion fatigue behavior of some special stainless steels. Corrosion Fatigue Technology, ASTM STP 642, pp. 117-132. Baumeister, T., E. A. Avallone, and T. Baumeister HI, eds. (1978). Mark s Standard Handbook for Mechanical Engineers, 8th ed., McGraw-Hill, New York. 

D ye penetration inspection. This is a simple technique, requiring a minimum of operator training. In the hands of a skilled operator, it is capable of detecting fine cracks such as chloride stress corrosion cracks in austenitic stainless steels and fatigue cracks. 

Fatigue life can be slightly lengthened by anodic protection or by passivation. In acids even passive stainless CrNi steels suffer corrosion fatigue [104]. Resistance can occur if the passive film itself has a fatigue strength (e.g., in neutral waters [105]). 

Valves must be made of fatigue-resistant carbon or alloy steel or 18-8 stainless steel, depending upon the service. The 18-8 stainless and 12-14 chrome steel is often used for corrosive and/or high temperature service. Any springs, as in the plate-type valves, are either carbon or nickel steel. Valve passages must be smooth, streamlined, and as large as possi-... 

Fig. 8.72 Effect of applied potential on corrosion fatigue behaviour of a ferritic stainless steel in 3% NaCl (after Amzallag el al )...

The substitution of a more corrosion-resistant material, e.g. Monel metal or stainless steel, is often advocated but this is not necessarily a solution a 15% chromium steel, for instance, is prone to failure in corrosion fatigue because of the disruption of the normally protective surface film although as noted earlier some other materials are effective, e.g. Ti-6A1-4V alloys... 

Amzallag, C., Rabbe, P. and Desestret, A., Corrosion fatigue behaviour of some special stainless steels, ASTM STP 642, pp. 117-32 (1977)... 

Duplex stainless steel alloys are a mixture of ferritic (400 series) and austenitic (300 series) metals. They provide 1) resistance to stress corrosion and fatigue, 2) pitting resistance, 3) are suitable for a wide temperature range (-50°C to 280°C) and 4) are cost effective. In urea plants, duplex stainless steel is used to construct strippers, decomposers, condensers and pipe lines88. 

From studies of service behavior and from extensive laboratory investigations, the well-established terms stress-corrosion cracking (SCC) and corrosion fatigue have been shown to relate to a continuum of failure modes classified as environment-sensitive fracture. In many environments, the addition of stress, with associated strains, introduces a variable that can result in brittle failure in the sense of very limited plastic flow in otherwise ductile materials such as the stainless steels. Environment-sensitive fractures propagate at an advancing crack tip at which, simultaneously, the local stresses can influence the corrosion processes, and the corrosion can influence the crack-opening processes. Since these processes proceed by kinetic mechanisms, they are time and stress dependent with the result that the crack propagation rate can become very sensitive to the stress application rates. Conventional SCC usually has been associated with static stress, but this is seldom realized... 

Wei, R. P., and Gao, M., Micromechanism for Corrosion Fatigue Crack Growth in Metastable Austenitic Stainless Steels, in Corrosion-Deformation Interactions, T. Magnin and J. M. Gras, eds., Proc. CDI 92, Fontainebleau, France, Les Editions de Physique, Les Ulis, France (1993), 619-629. 

Fig. 9.58 FCGRs in 3% NaCI solution and in air for a ferritic stainless steel [224]. Reprinted, with permission, from ASTM STP 642, Corrosion-Fatigue Technology, copyright ASTM international. West Conshohocken, PA...

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