Determination of Steel Cleanliness in Ultra Low Carbon Steel by Pulse Discrimination Analysis-Optical Emission Spectroscopy Technique

Traditional techniques of inclusion size determination are time consuming and cannot be implemented for on-line quality control. With the development of pulse discrimination analysis – optical emission spectroscopy (PDA-OES), the on-line determination of inclusions has become possible. However, PDA-OES measures only the number of inclusions present in the steel irrespective of size. In the present paper, the potential of PDA to determine the inclusion size is evaluated by employing two methodologies: (i) obtaining the average inclusion size by dividing the difference of total and soluble aluminium concentration by the number of Al based inclusions for 200 industrial ULC heats and (ii) measuring the Al concentration for individual peak intensity for specific heats, giving the inclusion size distribution. The methodologies of inclusion size measurement by PDA-OES as well as the possible causes of the discrepancies obtained after comparison with the inclusion extraction technique are explained in detail.