Abstract
The characteristics of colored films on Type 304, Type 430 and Type 329J1 stainless steel formed in a solution containing chromic and sulphuric acid at 80°C were studied.
The composition and structure of each colored film were examined using Secondary Ion Mass Spectrometry (SIMS), Electron Spectroscopy for Chemical Analysis (ESCA) and Transmission Electron Microscope(TEM).
An uniform and bright color film was formed on Type 304, however, a dark color was observed on Type 430 and Type 329Jl. It was found that the nature of films depends upon the corrosion resistance of each stainless steel against a treatment solution. A lot of pits were found in the grains on Type 430. On thecontrary little corrosion occurred in that on Type 304. Corrosion local cells brought about a preferential growth of films near grain boundary. The uneven thickness of colored film on ferritic stainless steels is thought to give rise to the optical dispersion and to decline reflectance. Therefore, a dark color is observed.
