Determination of Oxygen, Nitrogen, and Hydrogen in Iron, Steel, Nickel-base, and Cobalt-base Alloys: Comparison of Analytical Performance Between Argon and Helium Carrier

Importance of the Topic

The accurate measurement of oxygen nitrogen and hydrogen in iron steel and nickel cobalt alloys is critical for product performance and integrity In steel production controlling oxygen limits prevents porosity and defects while nitrogen content influences mechanical strength and formability Excess hydrogen leads to embrittlement so rapid simultaneous analysis of all three gases improves quality control

Objectives and Study Overview

This study compares the analytical performance of the LECO ONH836 instrument using argon versus helium carrier gas for simultaneous determination of oxygen nitrogen and hydrogen in various alloy matrices It evaluates precision accuracy analysis time and gas recovery across sample forms including solid bars chips and powders

Methodology and Instrumentation

• Sample preparation involves surface cleaning followed by rapid quenching of hydrogen samples in cold media to minimize gas loss
• Calibration and blank routines follow standard methods from ASTM E1019 complemented by sampling guidelines in ASTM E1806 and ISO 14284
• Analysis uses a high power electrode furnace in automated drop mode with tailored integration delays power profiles and outgassing cycles for each carrier gas

Instrumentation

• LECO ONH836 high power electrode furnace analyzer
• Graphite crucibles nickel capsules electrode tips and sample handling accessories

Key Results and Discussion

Both helium and argon carriers achieve oxygen precision near 0.0005 mass percent nitrogen precision below 0.0017 mass percent and hydrogen precision under 0.7 ppm Helium offers shorter integration and outgas times yielding faster cycle durations while argon delivers comparable recovery and stability across all sample types

Benefits and Practical Applications

• Simultaneous multi gas analysis increases laboratory throughput
• Adaptable preparation workflows for molten solid chip and powder samples
• Robust traceable calibration with certified reference materials

Future Trends and Potential Applications

Emerging advances may include further automation of sample handling enhanced furnace control strategies and investigation of alternative carrier gases or gas mixtures to optimize speed and sensitivity Integration with complementary detectors such as mass spectrometry could extend analytical scope

Conclusion

The ONH836 analyzer provides reliable simultaneous determination of oxygen nitrogen and hydrogen in iron steel and nickel base alloys using either argon or helium carrier gas Helium yields time savings without sacrificing accuracy while argon remains a cost effective option Rigorous sample preparation and adherence to standard methods ensure high quality data

References

• ASTM E1019 Standard Test Methods for Determination of Carbon Sulfur Nitrogen and Oxygen in Steel Iron Nickel and Cobalt Alloys
• ASTM E1806 Standard Practice for Sampling Steel and Iron for Determination of Oxygen and Nitrogen
• ISO 14284 Steel and Iron Analytical Sampling and Preparation