Repassivation of 304 Stainless Steel Investigated with a Single Scratch Test

Abstract

Reformation of the passive film on 304 stainless steel (UNS S 30400) was investigated with a scratch test. Regrowth of the passive film was measured by recording the current that resulted from forming the scratch. Charge consumed during the reformation of the film was compared to wear produced by the scratch. The current density from an incremental area of the scratch was extracted from the measured current transients using the width of the scratch as a function of time. The maximum current density and the charge density were dependent linearly on the area fraction of bare surface. Other parameters used in the model of current transients did not change as the area fraction of bare surface changed. Results showed the passive film remained adherent to the surface of the stainless steel during the rubbing mode of wear.

Assessment of the surface state behaviour of Al71Cu10Fe9Cr10 and Al3Mg2 complex metallic alloys in sliding contacts

“…A dense nanometer thick chromium oxide surface film on such metallic alloys provides an efficient protection against wet corrosion [8]. Electrochemical transient measurements like impedance and electrochemical noise have been applied successfully for the characterisation of the surface state of such passivating materials immersed in liquid environments [9]. The surface state is also known to affect the tribological properties of materials, namely friction, wear and lubrication.…”

“…Surface films like oxides, hydroxides or even contaminants adsorbed from the environment, affect the tribological behaviour due to e.g. a modification of surface energy or short distance attraction/repulsion van der Waals forces [9].…”

Electrochemical evaluation of a corrosion fatigue failure mechanism in a duplex stainless steel

“…As a result, the current transients were analyzed by fitting the results to an equation derived by convolution of a bare surface generation function and a repassivation function, as suggested previously. [20,[23][24][25] A repassivation function of the type used by Adler and Waters [24] to represent repassivation of a 304 stainless steel provided an excellent fit to these results. This equation is [1] for t Ն t B and [2] for t Յ t B , where i B is the bare surface current density, n is the repassivation exponent, and t B is the average time an increment of surface area remains bare after being exposed by scratching.…”

“…This experimental method was specifically designed to produce a bare surface at a nearly constant rate during the scratching process to enable analysis by fitting the resulting transients to a convolution integral, as suggested by Alder and Walters. [20,[23][24][25] …”

Effect of Nitrogen on Crevice Corrosion and Repassivation Behavior of Austenitic Stainless Steel

“…As the passivation film on stainless steels is difficult to remove by cathodic reduction, mechanical means such as scratching or polishing are usually employed to destroy the film and expose a new surface so that the corrosion resistance can be evaluated from the repassivation mechanism. [14][15][16][17] In general, steels with high corrosion resistance are easily re-passivated, but it is more difficult to rebuild the passivation film, and easier to promote local corrosion on the steel loosing its anticorrosion characteristics. One available method to investigate the effect of nitrogen on local corrosion is to observe the repassivation behavior after mechanically destroying the passivation film.…”