Laser-induced breakdown spectrometry -: applications for production control and quality assurance in the steel industry

Recent progress in sensitivity and signal processing opened a broad field of application for laser-induced breakdown spectrometry (LIBS) in the steel making and processing industry. Analyzed substances range from top gas of the blast furnace, via liquid steel up to finished products. This paper gives an overview of R&D activities and first routine industrial applications of LIBS. The continuous knowledge of the topgas composition yields information about the blast furnace process. An online monitoring method using LIBS is currently under investigation to measure alkali metals, which influence energy and mass flow in the furnace. Direct analysis of liquid steel reduces processing times in secondary metallurgy. By using sensitivity-enhanced LIBS, limits of detection of approximately 10 mug/g and below were achieved for light and heavy elements in liquid steel. The process control in steel production relies on the results from the chemical analysis of the stag. A prototype of an analytical system was developed using LIBS to analyze stag samples two times faster than with conventional methods. The cleanness of steel is a key issue in the manufacturing of spring steel, thin foils and wires. Microscopic inclusions have to be determined quickly. A scanning microanalysis system based on LIBS was developed with measuring frequencies up to 1 kHz and a spatial resolution of < 15 mum. For the final inspection of the steel grade of pipe fittings, an inspection machine using LIBS was developed and introduced into routine industrial use to detect material mix-ups. More than 500 000 pipe fittings were inspected during the last 20 months. (C) 2001 Elsevier Science B.V. All rights reserved.