THE PROBLEM:

A sample of a corroded stainless steel panel was received with the request that we identify the cause of the corrosion.

THE ANALYSIS:

Visual and stereomicroscopic inspection of the panel indicated widespread pitting and corrosion (Figure 1).

A portion of the panel was cut and analyzed using a scanning electron microscope (SEM) equipped with an energy dispersive x-ray spectrometer (EDS). A backscattered electron image of a pit shows the corrosion (Figure 2), and the associated EDS spectrum reveals the components of the corrosion (Figure 3).

The high peak associated with chlorine (Cl) indicates chloride in the corrosion product. Chromium (Cr) and iron (Fe) are the base metals of the stainless alloy, and a spectrum of the base alloy away from any corrosion is displayed for comparison (Figure 4).

THE OUTCOME:

The corrosion of this steel panel is consistent with pitting corrosion associated with chloride attack.