Determination of Carbon in Low-Alloy Steels by Laser Atomic-Emission Spectroscopy in Air

A technique for rapid determination of carbon content in low-alloy steels was developed based on laser atomic-emission spectroscopic analysis. The C I 909.483-nm carbon line in the near-IR region was chosen as the analytical line. The conditions were optimized for recording spectra in this region. Switching to double-pulse mode for excitation was shown to enhance the spectral intensities of elements included in the analyte and to reduce the line intensities of elements included in air so that this line could be analyzed under normal atmospheric conditions. A calibration curve was constructed for carbon steels and was linear for the practically important carbon concentration range in this steel grade. Measurement error in the carbon concentration and the influence of carbon pollutants in workplace air on its determination were evaluated.