Online Compositional Analysis of Molten Steel by Laser-Induced Breakdown Spectroscopy

Quick analysis of chemical composition is very important for process control and quality assessment in metallurgical industry, especially in steelmaking process. A prototype equipment for online analysis of molten steel composition was developed based on laser-induced breakdown spectroscopy. The effect of steel temperature on different spectral line intensities was studied, and calibration curves of Cr, Ni, Si and Mn were built. Results show that most line intensities are greatly enhanced when steel temperature is higher than 1200 degrees C, and the detection capability of minor elements in molten steel is higher than in normal solid steel. Line intensity, however, is easier saturated in molten steel, leading to narrow linear ranges of calibration curves for molten steel. Furthermore, for online analysis, by using a median filter the abnormal points were inhibited and the changing compositional concentrations were successfully monitored