A study has been performed experimentally to determine the effects of surface roughness, damaged surface layer and chemical composition on the specular spectral reflectance of A1SI304 austenitic stainless steel from the machining point of view. Stainless steel samples are heat-treated under various conditions and polished by various methods. Flat samples are polished supersmoothly to a surface roughness of 20 angstroms Rz by terminating the damage-free polishing of the damaged surface layer at a point prior to the appearance of the grain boundary due to crystallographic anisotropy. The reflectance is strongly dependent on wavelength and surface roughness and increases as damage to the surface layer decreases. The combination of adequate annealing and special polishing is useful to produce higher reflectance on metal substrates. Surface chemical composition profiles are measured by ILIA and ALS, which show that chromium is depleted at the very topmost oxidized layer on the polished sample, while there is a chromium-rich oxide layer beneath the layer. The thickness of the oxide layer is about 30 angstroms on the supersmoothly polished stainless steel.
"Specular Spectral Reflectance Of ALS1304 Stainless Steel At Near-Normal Incidence", Proc. SPIE 0362, Scattering in Optical Materials II, (5 April 1983); doi: 10.1117/12.934138; https://doi.org/10.1117/12.934138