Bulk Analysis of a Plain Carbon Steel Sample Taken With an Immersion Sampling Probe

Importance of Topic

The accurate and rapid analysis of bulk steel composition is crucial for quality control in metallurgical processes. Monitoring alloying elements during steel production ensures that the final product meets stringent grade specifications, reducing scrap and optimizing material performance. Advanced atomic emission techniques provide reliable detection of trace and major constituents in conductive materials.

Study Objectives and Overview

This application note demonstrates the capability of the LECO GDS900 glow discharge atomic emission spectrometer to perform bulk composition analysis on plain carbon steel samples obtained using a dual-thickness immersion sampling probe. The study compares results from thin and thick disk sections to assess sample homogeneity and validates carbon and sulfur measurements against combustion analysis using the LECO CS744 instrument.

Methodology and Instrumentation

• Sampling: Liquid steel was sampled with an immersion probe conforming to ASTM E1806-18, producing a dual-thickness disk.
• Sample Preparation: Disks were separated into thin and thick sections using a water-cooled saw, followed by surface linishing with a 120-grit zirconium oxide belt to remove oxide layers.
• Spectrometer Configuration: LECO GDS900 equipped with a glow discharge source and CCD-based detection. Calibration employed certified reference materials from NIST, Brammer, CKD, MBH and IARM, with drift correction via homogeneous setup standards.
• Combustion Analysis: Carbon and sulfur in the thin section were measured with the LECO CS744, providing an independent reference method.

Main Results and Discussion

• The GDS900 delivered reproducible elemental concentrations for both thin and thick sections. Key elements (C, Cr, Cu, Mn, Ni, Si, S) showed relative standard deviations below 2%, indicating high precision.
• Carbon content averaged 0.154 % (thin) and 0.153 % (thick), while sulfur was 0.0273 % and 0.0270 %, confirming homogeneity across disk thicknesses.
• Trace elements such as cobalt and zirconium exhibited slightly higher RSD values but remained within acceptable analytical limits.
• Combustion results from the CS744 yielded carbon at 0.158 % and sulfur at 0.0288 %, closely matching GDS900 data and validating the glow discharge approach.
• Glow discharge sputtering produced clean craters without sample damage, enabling three consecutive burns without repositioning and completing analyses in as little as 90 seconds.

Benefits and Practical Applications

• Rapid, minimally destructive bulk analysis of conductive materials with straightforward sample preparation.
• High throughput: multiple analyses in under two minutes support real-time production monitoring.
• Robust calibration and linear response across a wide concentration range reduce spectral interferences and simplify method development.
• Applicable to both ferrous and nonferrous alloys in production, quality assurance and research laboratories.

Future Trends and Opportunities

Advancements in glow discharge sources, detector technologies and data processing algorithms will further enhance sensitivity, speed and usability. Integration with automated sampling and real-time process control could enable closed-loop feedback in steelmaking operations. Expanding calibration libraries for new alloys and trace elements will broaden the methodology’s industrial applications.

Conclusion

The LECO GDS900 has proven to be a reliable and efficient instrument for bulk analysis of plain carbon steel, delivering fast and precise elemental data. Its ability to analyze both thin and thick disk sections highlights the uniformity of immersion sampling and glow discharge excitation. This technique is ideally suited for routine quality control and process monitoring in metallurgical environments.

Reference

Application Note: Bulk Analysis of a Plain Carbon Steel Sample Taken with an Immersion Sampling Probe, LECO Corporation, 2019