Determination of AlN and Al 2 O 3 in steels by electrolytic separation and wavelength dispersive X-ray fluorescence spectrometry

Abstract

The determination of non-metallic aluminium inclusions in steel samples, mainly consisting of AlN and Al2O3, can be performed with the aid of their X-ray fluorescence Kβ-line. The enrichment of these inclusions with an electrolytic isolation is described and shown to enable the analysis of samples with even very low aluminium content. The absolute detection limit of the combined electrolysis and X-ray fluorescence spectrometric detection using the Al-Kβ line was found to be 3 μg Al in the residue that is below 0.001 mass-% in the steel sample under the given conditions. Due to low spectral resolution a deconvolution of the obtained data is required, but then a detection limit of 1.8 mass-% Al2O3 and 0.4 mass-% AlN in the binary mixture can be achieved. Sixteen samples of two low-alloyed steel qualities with a total amount of insoluble aluminium in the range of 0.003 to 0.013 mass-% have been analyzed with the procedure developed.