On colors of stainless-steel surfaces polished with magnetic abrasives

Multiple colors visible to the naked eye across internal surfaces of stainless-steel 304 tubes polished with a magnetic abrasive finishing (MAF) process were investigated at varying levels magnification. The found result from microscopic colored features four different hues — green, blue, red, and yellow having irregular sizes shapes. Spectral analysis their dispersion indicates that these appear along lay marks generated during MAF. Surface characterization employing energy dispersive spectroscopy instrumented indentation testing presence films non-stochiometric chromium oxide nickel in regions. Variations momentum density particles interacting surface MAF process, together chemical composition morphology surface, provide thermodynamic conditions favorable for non-uniform growth oxides film. Local color is dependent on local thickness