Carbon and Sulfur Determination in High Carbon Ferroalloys

Significance of the Topic

Accurate determination of carbon and sulfur in high carbon ferroalloys is critical for steel and cast iron production. Carbon controls mechanical properties and hardness, while sulfur is a detrimental impurity that can compromise ductility and toughness. Reliable analysis ensures optimal alloy composition and consistent quality control in metallurgical processes.

Objectives and Study Overview

This application note describes a rapid combustion method for simultaneous measurement of carbon and sulfur in high carbon ferroalloy samples. It outlines sample preparation, instrument setup, calibration procedures, and performance evaluation using certified reference materials.

Used Methodology and Instrumentation

Combustion is performed on a LECO CS230/CS600 analyzer under controlled conditions. Key steps include:

• Sample pretreatment with iron powder, vanadium pentoxide (V2O5), and LECOCEL accelerator.
• Blank determination with iron powder, V2O5, and LECOCEL in preheated ceramic crucibles.
• Calibration using NIST 64c and BCS 204/4 reference materials over multiple replicates.
• Sample analysis following blank and calibration sequences.

Typical parameters: purge time 10 s; delay time 25 s; comparator level 1.00; five significant digits; carbon timeout 50 s; sulfur timeout 55 s.

Main Results and Discussion

Analysis of NIST 64c (4.68 % C, 0.067 % S) yielded an average of 4.688 % C (SD 0.009) and 0.0670 % S (SD 0.0007). BCS 204/4 (5.62 % C, 0.010 % S) produced 5.620 % C (SD 0.005) and 0.0102 % S (SD 0.0001). Results demonstrate high precision, stable blanks, and accurate calibration with single-standard curves for each element.

Benefits and Practical Applications

• Fast turnaround times suitable for high-throughput quality control.
• Low detection limits and high reproducibility for both carbon and sulfur.
• Robust method adaptable to a variety of high carbon ferroalloys.
• Automated workflow reduces operator variability.

Future Trends and Potential Applications

Advances may include integration with real-time data analytics, expansion to multi-element combustion analysis, enhanced automation with robotic sample handling, and coupling with AI-driven process control to further optimize steelmaking feedstock quality.

Conclusion

The described combustion method on a LECO CS230/CS600 delivers precise and accurate carbon and sulfur determinations in high carbon ferroalloys. Consistent calibration and well-controlled blanks ensure reliable routine analysis, supporting robust quality assurance in metallurgical operations.

Used Instrumentation

• LECO CS230/CS600 Carbon/Sulfur Analyzer
• LECO TF10 muffle or tube furnace for crucible baking
• 528-018 preheated ceramic crucibles and 619-880 covers
• Iron powder (LECO 501-078), V2O5 (501-636-HAZ), LECOCEL accelerator