Critical Characteristic Dimension or Geometry for Determining the Susceptibility of a Crevice to Crevice Corrosion

Abstract

Crevices are invariably present in engineering structures. Hence, it is of interest to develop the ability to predict which geometries will, or will not, lead to crevice corrosion. Since many crevice corrosion theories have been proposed that depend on the material-environment combination, two systems have been selected for study: mild steel (MS) under anodic polarization in a sodium acetate-acetic acid buffer solution (NaAc-AcH) and Al in a sodium chloride (NaCl) solution. The onset of crevice corrosion is respectively believed to be determined by a critical potential drop (IR drop theory for MS in NaAc-AcH) and a critical species' concentration (critical crevice composition theory for Al in NaCl). In both cases, these critical values can be translated, by computation, into a critical characteristic crevice dimension determining the onset of crevice corrosion in one-dimensional crevices. The critical characteristic dimension marks the limit between crevices that show or do not show crevice corrosion. The calculations for the system where the critical crevice composition theory is operative have been performed with a fi nite element code to describe the mass transport of the various species involved. This approach allows the criterion (critical potential drop or critical crevice composition) to be evaluated for crevices of any geometry in real components.

A Review of the Application of Finite Element Method (FEM) to Localized Corrosion Modeling

“…Both Vankeeberghen 88 and Lee, et al, 41 explored the effect of crevice geometry on the susceptibility of a crevice to crevice corrosion by investigating the existence and form of a scaling factor that relates depth and gap to geometric conditions needed to establish crevice corrosion. Lee, et al, combined FEM modeling and experimental methods to rigorously study the most two commonly proposed scaling laws: x crit /G and x 2 crit =G, where x crit is d c referred by Xu and Pickering, 32 and G is crevice gap width.…”

The crevice corrosion of Alloy 22 in the Yucca Mountain nuclear waste repository

“…The ratios x 2 /g and x/g are the parameters most commonly used as scaling factors for correlations in the study of geometrical aspects of crevice corrosion. [56][57][58][59][60] Therefore, the material of the crevice former and the torque applied to it are of fundamental signifi cance in crevice corrosion susceptibility. Factors affecting the crevice geometry, and the surface roughness and mechanical properties of the crevice former, could affect the severity of crevice corrosion.…”

Susceptibility of 316L stainless steel to crevice corrosion in submersible solenoid valve

“…The effects of variables, such as crevice former materials, applied torque on crevice formers, chemical elements and crevice geometries on crevice corrosion behavior, have been studied [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”