Comparison between multiwavelength infrared and visible pyrometry: Application to metals

A device for non-intrusive temperature measurements of metallic materials has been developed. Moreover, as the emissive properties of the metal cannot be known a priori, multiwavelength pyrometry was used to address this issue in the following way:– Simultaneous measurement of thermal emission at N wavelengths.– Use technique of parameter identification including a physical or an empirical model for the emissivity to determine temperature and spectral emissivity.This method was applied to a temperature range between 500 K and the melting/solidification point of the metallic materials. The results obtained in visible and infrared spectral range were compared. Various metallic samples were studied (steels, titanium), and for each sample, the relative deviation between identified and experimental (thermocouple) temperatures is lower than 2%, using the more suitable models. For some groups of materials (austenitic stainless steels, and carbon steels), one or several models giving suitable results for similar samples were selected.