The element concentration of carbon (C), sulfur (S), hydrogen (H), nitrogen (N), and oxygen (O) in iron products, such as steel, have a significant influence on material properties like ductility, brittleness, or hardness. Hence, reliable determination of the C, H, N, S, O contents is a routine quality control task in steel and iron production. This article explores the application fields and advantages of elemental analyzers, which are also known as combustion analyzers, in the steel industry.
Different analytical methods
A great variety of different analytical methods are used in steel and iron production1. Disregarding analyses of physical parameters, such as hardness or tensile strength, and focusing solely on chemical analyses, the different techniques can be categorized, for example, with regard to the measurement method applied (AAS, OES, photometry, mass spectrometry, etc.). A common differentiation is made between wet chemical techniques which require sample digestion, e.g. by ICP-OES, and direct analysis methods like spark spectrometry or combustion analysis. Another possible classification could be made for total element analysis as opposed to surface or layer analysis. The following article mainly focuses on the differences between spark spectrometry and combustion analysis as these are the most common and established techniques for measuring concentrations of C, H, N, S, O. Moreover, both methods are hardly mentioned in general textbooks about analytical chemistry2, despite the fact that they are widely used in laboratories and production.