The Effect of Long-Term Oxidation on the Total Hemispherical Emissivity of Type 316L Stainless Steel

The effect of long-term oxidation on the total hemispherical emissivity of Type 316L stainless steel (SS 316L) is of interest in nuclear plant safety and is reported on here. ASTM standard C835-06 [American Society for Testing and Materials, 2006]was used for measuring the total hemispherical emissivity of this material for the following surface conditions: (1) as-received from the manufacturer (essentially unoxidized) and (2) oxidized in air at 573 K for up to 3000 h. The emissivity of the as-received samples varied within the range from 0.24 at 434 K to 0.34 at 1026 K. Oxidation in air at 573 K for 500 h increased the emissivity range of the oxidized sample from 0.28 at 429 K to 0.38 at 1096 K. There was no further significant change in emissivity observed following an increase in the oxidation time from 500 to 3000 h. It is suspected that the emissivity ceased to increase during the additional oxidation time because of chromium oxide that formed on the SS 316L surface inhibiting further oxidation.