The influence of in-coating strontium chromate (SrCrO4) pigment dispersions on the kinetics and mechanism of HCl-induced filiform corrosion (FFC) affecting polyvinyl butyral coated AA2024 T3 aluminum alloy is studied using a scanning Kelvin probe. FFC initiation and propagation are detected by imaging time-dependent changes in local free corrosion potential (E-corr) distribution patterns. Area rates of coating delamination fall from 1.25 x 10(-8) m(2) min(-1) to zero as the SrCrO4 volume fraction (phi(SC)) is increased from zero to 0.06. Increasing phi(SC) over the same range produces minimal change in filament-head E-corr values but depresses filament tail and intact coating E-corr values by up to 0.3 V. It is proposed that filament tail E-corr depression results from increased polarization of cathodic O-2 reduction reactions at sites of high pH, where insoluble Cr(OH)(3) is the predominant CrO4 (2-) reduction product. It is further proposed that intact coating E-corr depression results from reversible, nonfaradaic adsorption of CrO42- at the oxide-covered aluminum surface. Both effects are implicated in FFC inhibition, as is pH buffering by SrCrO4 which acts in conj. unction with CrO42- adsorption to forestall anodic attack at the coating-substrate interface. (C) 2004 The Electrochemical Society.