The nucleation, growth and stability of micropits in stainless steel

摘要: Abstract The probability of the formation a propagating pit in stainless steel is expressed as product nucleation metastable micropit and transition from to stable propagation micropit. Factors controlling initiation maintenance pitting corrosion are separated by analysis current transients which signal initiation, repassivation micropits. A model gives full description form derived simple statement factors stability micropits, chiefly relating their geometry, obtained. Micropits unstable increases mouth radius decreases surface exchange density. Sulphide inclusions act increase density, molybdenum additions decrease it. volume fraction sulphide main factor affecting rate micropits; effect addition alloy appears minor comparison. be density at thereby that will make continued, growth. Analysis variations frequency with preformed film thickness, time potentiostatic experiments, potential scan potentiodynamic experiments indicates importance feedback processes coupled passive In some circumstances, can used comparative assessment risk, but comparison between different compositions misleading overly conservative. relationship results statistical studies single measurements breakdown derived.