Mechanisms and Modelling of Cracking under Corrosion and Fretting Fatigue Conditions

Author:  de los Rios
Source:  Conf Proc: ICSP-8 Sept. 16-20, 2002 Garmisch-Partenkirchen, Germany
Doc ID:  2002033
Year of Publication:  2002
Author Eduardo R. de los Rios, Department of Mechanical Engineering, University of Sheffield, Sheffield, UK Corrosion Fatigue It is well established that crack growth proceeds at a higher rate in aggressive environments than in air. This complicates even further the prediction of fatigue life, where safety factors are required to account for these uncertainties. However, considering that these correction factors are derived from projected service conditions (which are shortened in time for laboratory testing), make questionable the accuracy of the predictions, although designs are evaluated through service simulation tests. To increase the accuracy of the predictions it is necessary to develop models of corrosion fatigue that incorporate the main aspects of the physical phenomena. These aspects of the environmentally assisted corrosion fatigue of metals in aqueous solutions involve electro-chemical processes which include anodic and cathodic reactions. The former is related to an anodic dissolution mechanism and the latter is associated with hydrogen embrittlement. Several possible corrosion fatigue mechanisms related to anodic dissolution have been suggested, including pitting induced crack initiation and short crack growth, film-rupture, dissolution of slip bands at the crack tip and grain boundary oxidation. Of these, pitting corrosion is the most damaging and will be discussed next.

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