Turnbull, A; Wright, L; Crocker, L E (2010) New insight into the pit-to-crack transition from finite element analysis of the stress and strain distribution around a corrosion pit. Corros. Sci., 52 (4). pp. 1492-1498.

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Abstract

A finite element (FE) analysis has been undertaken to evaluate the stress and strain distribution associated with a single corrosion pit in a cylindrical specimen stressed remotely in tension. Hemispherical and bullet-shaped pits of 100 mm and 500 mm depth respectively were investigated at varying applied stresses up to 90% of the 0.2% proof stress for a steam turbine disc steel, the pit shapes reflecting, crudely, shallow and deep pits respectively. A key observation was the localisation of plastic strain to the pit walls, just below the surface of the specimen, this localisation becoming more pronounced for the deeper pit. In the absence of plastic strain the stress was also localised in this region below the pit mouth but, with plastic deformation, redistribution occurred towards the pit base. Of most significance, simulation of a growing pit in a static stress field indicated plastic strain rates that were commensurate with values associated with stress corrosion cracking. This observation introduces a wholly new concept in understanding of the evolution of stress corrosion cracks from pits. These model predictions correlated with recent X-ray tomography measurements showing that stress corrosion cracking was initiated predominantly at or just below the surface.

Item Type:	Article
Keywords:	pit, stress corrosion cracking, finite element
Subjects:	Advanced Materials Advanced Materials > Corrosion
Last Modified:	02 Feb 2018 13:15
URI:	http://eprintspublications.npl.co.uk/id/eprint/4631

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