Effects of surface condition on the infrared absorptivity of 304 stainless steel

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Abstract
The absorptivity of 304 stainless steel at 10.6 μm has been obtained between room temperature and 1000 °C by laser calorimetry. Highly polished specimens have been compared with as‐received and rough‐polished specimens in order to determine the effects of surface condition on the absorptivity. When the surfaces are well annealed, the calorimetry data show that the absorptivities of the highly polished surface and the rougher surfaces are nearly the same over the entire range of temperature. No influence of grain size on the absorptivity has been observed, despite the substantial growth of the grain boundaries at elevated temperatures. When the surfaces are deformed by cold rolling or rough polishing, the absorptivity at room temperature increases by 22–27% due to increased scattering from nonplanar defects within the surface layer. The absorptivity data on damage‐free surfaces of stainless steel have been found to agree closely with the predictions of generalized Drude theory, applied to disordered alloys. The calorimetry data have also been used to calculate the hemispherical emissivity of 304 stainless steel between 400 and 1000 °C.