Effect of Laser Surface Melting on Some Corrosion Characteristics of an Iron‐Chromium Alloy

Abstract

The effect of laser surface melting (LSM) on the breakdown of the passivating film and subsequent pitting of a ferritic stainless steel has been studied. An Fe‐19%Cr alloy was subjected to LSM by pulses from a Q‐switched Nd‐YAG (1.06 μm) laser. The composition of the native oxide film was analyzed by Auger electron spectroscopy. Although LSM enriches the surface oxide film in chromium, it degrades its electrochemical behavior, for there is premature breakdown of the passivating film and subsequent pitting when the electrochemical potential is swept from the passive region into the active region in . The premature breakdown occurs at sites associated with inclusions. Stresses introduced in the surface by LSM affect pit growth rates and morphology in the same manner as when they are introduced by mechanical means.