Determination of Hydrogen in Reactive and Refractory Metals

Significance of the Topic

Low hydrogen levels are critical in reactive and refractory metals such as titanium and zirconium alloys to prevent hydride formation and embrittlement under mechanical stress. Accurate hydrogen determination supports quality control in medical, aerospace, military, and other high-performance applications.

Objectives and Overview

This note describes an analytical protocol for quantifying hydrogen in metallic samples using inert gas fusion combined with thermal conductivity detection. The approach follows ASTM E1447 and demonstrates application on both solid and powder/chip matrices.

Methodology

Samples (0.15–0.3 g) are prepared by shearing or abrasion, cleaned, and handled to avoid contamination. Each is combined with tin flux pellets in a graphite crucible. The crucible is heated in an impulse furnace under argon flow, releasing H2 which is separated from other gases and measured via a thermal conductivity cell. Critical timing and current parameters ensure optimal gas evolution and detection.

Used Instrumentation

LECO H836EN analyzer with:

• High-temperature graphite crucibles
• Tin flux pellets and capsules
• Electrode tips and tweezers
• Argon carrier gas and reagent modules for CO2 and moisture removal

Reference materials included LECO Certified Reference Materials and NIST standards.

Main Results and Discussion

Linear calibrations (forced through origin) were established using titanium reference pins and powders. Solid sample recoveries ranged from ~8 to 108 ppm H with standard deviations between 0.5 and 5 ppm. Powder and chip samples yielded 7.6 to 260 ppm H with RSDs near 0.3–1 ppm, confirming method precision and consistency across matrices.

Benefits and Practical Applications of the Method

The described protocol offers rapid, reproducible hydrogen analysis essential for quality assurance in alloy production and processing. It enables detection of low ppm hydrogen levels to prevent material embrittlement and supports process control during heat treatment, pickling, and machining.

Future Trends and Potential Applications

Advances may include higher automation, coupling with infrared detection for enhanced sensitivity, reduced sample sizes, and integration with digital data workflows. Adaptation to emerging alloy systems and miniaturized analyzers may broaden industrial applicability.

Conclusion

The inert gas fusion method on the LECO H836EN instrument provides accurate, reliable hydrogen quantification in reactive and refractory metals, fulfilling stringent industry standards and safeguarding material integrity.

References

• ASTM E1447 - Standard Test Method for Determination of Hydrogen in Reactive Metals and Reactive Metal Alloys by Inert Gas Fusion with Detection by Thermal Conductivity or Infrared Spectrometry