Carbon Analysis in Steel

Steel, a versatile alloy of iron and carbon, is renowned for its exceptional strength and durability. Its properties can be altered by modifying its elemental composition – with carbon being the most influential alloying element. Practically speaking, increasing carbon content increases hardness and strength and improves hardenability. However, this also renders the steel more brittle and reduces its weldability. Therefore, it comes as no surprise that keeping carbon content within the desired range is a priority for steel manufacturers. 

Laser-Induced Breakdown Spectroscopy (LIBS) stands out as an effective method for assessing carbon content in steel. To put this to test, our laboratory technicians at AtomTrace utilized our Sci-Trace instrument with our vacuum interaction chamber to analyze carbon levels in three steel samples. The results were compared with values obtained from measuring five steel standards. To assess the data and determine carbon content in the samples, the carbon line C I 247.856 nm was selected. The use of argon as the ambient atmosphere ensured a controlled environment, minimizing interference and enhancing accuracy.

Figure 1 shows the calibration curve generated after measuring the calibration standards, which was used to determine the carbon content of the samples. The coefficient of determination R² expressing the quality of the regression fit is R² = 0,9750. 

Figure 1: Carbon calibration curve in steel standards

Table 1: carbon contents found in the 3 measured unknown tool steel samples.

Our study demonstrates that our Sci-Trace and M-Trace instruments are able to achieve accurate carbon content measurements in steel, especially within an argon atmosphere. By establishing a calibration dependency from carefully measured standards, we were able to reliably determine the carbon content in steel components.