Carbon and Sulfur Determination in Low Carbon Ferroalloys

Importance of the Topic

The accurate measurement of carbon and sulfur in low carbon ferroalloys is critical for controlling mechanical properties, corrosion resistance and overall quality of steel and cast iron.

Objectives and Study Overview

This application note outlines two analytical methods using the LECO CS230/CS600 instruments to quantify trace levels of carbon and sulfur in ferroalloy feed stocks. It aims to provide optimized procedures for sample preparation, calibration and analysis to achieve high precision and reliability.

Methodology

• Sample Preparation: Uniform powder or granular samples baked in ceramic crucibles at high temperature to remove contaminants and stored in a desiccator.
• Method 1 Accelerators: LECOCEL II HP and Iron Chip HP; Method 2 Accelerators: LECOCEL, Iron Powder and vanadium pentoxide.
• Analysis Conditions: Approximately 0.25 g sample, blank determination, calibration/drift with certified reference materials, and three to five replicate runs for blanks, calibration and samples.

Instrumentation

• LECO CS230/CS600 Carbon and Sulfur Analyzers
• LECO TF10 Muffle Furnace for crucible baking
• Ceramic Crucibles (528-018) and Crucible Covers (619-880)
• Accelerator materials and metal scoops

Key Results and Discussion

Method 1 delivered average carbon levels around 0.016±0.001 % and sulfur around 0.065±0.001 % on standard materials, demonstrating excellent repeatability. Method 2 achieved similar precision with average carbon of 0.017±0.001 % and sulfur of 0.065±0.001 %, despite a higher carbon blank that is effectively corrected. Both methods provided consistent detection limits below 0.001 % for sulfur in some standards and maintained robust performance across multiple alloys.

Benefits and Practical Applications

• Rapid, high-throughput analysis with minimal sample mass
• Automated operation compatible with autoloaders
• Reliable trace quantification for quality control in steel production

Future Trends and Opportunities

Emerging needs include adapting these methods for complex alloy matrices, integrating data with laboratory information management systems, and developing novel accelerators to further reduce blank contributions and improve detection capabilities.

Conclusion

The two validated methods on the LECO CS230/CS600 platforms deliver accurate and precise carbon and sulfur measurements in low carbon ferroalloys, supporting stringent quality control requirements in metallurgical processes.

References

• LECO Corporation. Carbon and Sulfur Determination in Low Carbon Ferroalloys. Application Note Form No. 203-821-441, 2013.