New findings in the spectrometric determination of steel nitrogen levels

Abstract

The efficiency of analyzing nitrogen by optical emission spectroscopy was put to test in a first publication by six German laboratories of the iron and steel industry. Further experiences with this new method accumulated in the meantime will be reported here. By taking into account interelement effects both the residual scatter and BEC (background equivalent concentration) values for alloy steels have clearly been improved. The detection limit was determined at 6 μg/g by using the repeatability standard deviation in the range of the spectral background. Precipitates of titanium nitrides or carbon nitrides lead to high scatter of measured values. The long‐term stability of the spectrometric measuring system is largely dependent on the purity of the argon gas, transmission conditions in the spectral apparatus, the properties of the excitation unit, and the quality of the specimen surface. To all these items recommendations for practice are given.