In-Situ Spectral Emissivity Measurement Of Alloy Steels During Annealing In Controlled Atmosphere

laboratory set-up to simulate the annealing conditions of a hot-dip galvanizing line is employed to track the radiometric property evolution of alloy steel during the heating and soaking. A variation of the dew point of the annealing atmosphere yields different morphology and chemical composition of the surface oxides. In-situ emission spectra are acquired by a LWIR spectrometer (8-12 mu m) and post-annealed sample characterization is performed using field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy. It is found that apart from the chemical composition, surface roughness which is caused by the oxide morphology and the distribution of oxide in the depth contribute to the overall emissivity variation.