Why Choose an ONH Analyzer for QC in Metals

Quality control decisions are only as reliable as the data behind them. For metals, analyzing alloy composition alone leaves a critical gap because oxygen, nitrogen, and hydrogen remain hidden within the material’s structure. Choosing an Oxygen, Nitrogen, and Hydrogen (ONH) analyzer delivers precise measurement of these interstitial gases, helping manufacturers make informed decisions that protect product quality throughout production.

Interstitial Gases And Their Impact On Metal Performance

Although hydrogen, nitrogen, and oxygen exist in trace concentrations, their influence on mechanical performance is far from insignificant. Melting, casting, heat treatment, and welding can introduce them into a metal matrix, where they alter material behavior in ways that standard chemical analysis cannot detect. Without accurate measurement, manufacturers risk producing materials that fall outside specification despite meeting conventional compositional requirements.

Hydrogen presents a well-known challenge to high-strength steels and welded fabrications because of its association with hydrogen embrittlement. Under stress, dissolved hydrogen migrates through the crystal lattice, increasing susceptibility to delayed cracking and unexpected component failure. Pipelines, pressure vessels, and structural fabrications all depend on careful hydrogen control to maintain long-term reliability.

Nitrogen presents a different issue. Deliberate additions of nitrogen improve the performance of selected alloys, yet uncontrolled concentrations, reduce ductility, promote strain aging and increase brittleness. Oxygen introduces another layer of risk by forming brittle oxide inclusions that act as stress concentrators, lowering toughness and raising the risk of fatigue cracking.

Collectively, hydrogen, nitrogen, and oxygen influence far more than laboratory test results. Poor control can lead to rejected production batches, costly rework, delayed deliveries, and reduced service life in demanding sectors like aerospace, automotive, energy, and medical manufacturing.

How ONH Analysis Works

ONH analysis measures the concentration of oxygen, nitrogen, and hydrogen dissolved within a metal sample. Most modern ONH analyzers perform this measurement using Inert Gas Fusion (IGF), an analytical technique that extracts interstitial gases from the sample before measuring them with dedicated detectors. Complete gas extraction allows laboratories to determine total oxygen, nitrogen, and hydrogen content with high accuracy and repeatability, making IGF the preferred method for metallurgical quality control.

The process behind IGF follows four stages:

• A prepared metal sample is placed into a high-purity graphite crucible
• An impulse furnace rapidly melts the sample within a flowing stream of helium or argon, releasing dissolved gases from the metal
• Oxygen reacts with the graphite crucible to form carbon monoxide and carbon dioxide, allowing nitrogen and hydrogen to remain available for measurement
• Nondispersive infrared detectors quantify oxygen while thermal conductivity detectors determine the concentrations of nitrogen and hydrogen.

By measuring the total gas content extracted from the sample, an ONH analyzer delivers reliable data for production monitoring, process optimization, and compliance with metallurgical quality standards.

Reasons to Choose an ONH Analyzer for QC in Metals

Laboratories invest in ONH analysis because interstitial gases demand a level of precision that conventional elemental analysis cannot provide. The key reasons for selecting an ONH analyzer for QC in metals include:

• Rapid analysis- producing results within minutes to support timely sample evaluation
• High analytical sensitivity- detecting oxygen, nitrogen, and hydrogen at sub-parts-per-million concentrations
• Excellent repeatability- delivering consistent results across routine and high-throughput testing
• Compliance with recognized ASTM and ISO standards- establishing standardized analytical procedures
• Material versatility- accommodating diverse metals and alloys.

Combined, these qualities enable laboratories to generate reliable analytical data for routine testing, process development, failure investigations, and research applications.

ONH Solutions for the Modern Lab

No two metallurgical laboratories operate under the same conditions. Sample volumes, testing priorities, and analytical requirements all influence which ONH analyzer is the most suitable fit.

The G6 LEONARDO is designed for laboratories undertaking routine industrial testing. A library of pre-calibrated analytical methods support commonly tested materials, reducing method setup and helping laboratories achieve consistent results during standard analysis. Straightforward operation and efficient analytical workflows make the system particularly useful for steel producers, foundries, and manufacturing laboratories where large numbers of samples are processed as part of routine quality assurance. Efficient day-to-day operation assists users with maintaining high sample throughput alongside dependable analytical performance.

The G8 GALILEO is intended for laboratories with broader analytical requirements. Beyond ONH determination, it measures diffusible hydrogen in welds, offering a detailed assessment of weld integrity and hydrogen-assisted cracking. The system can also be applied to advanced materials characterization, method development, and investigative analysis across complex alloys and specialized manufacturing processes.

Whether the priority is routine production testing or advanced materials research, matching analytical capability to laboratory workflows ensures the ONH analyzer continues to meet analytical demands as testing needs evolve.

Your Partner in ONH Analysis

XRF Scientific supplies elemental analyzers for oxygen, nitrogen, and hydrogen determination that help metallurgical laboratories achieve accurate measurements in demanding production environments like steel mills, foundries, and metals manufacturing facilities. In addition to supplying advanced ONH analysis systems, including the G6 LEONARDO and G8 GALILEO, customers can benefit from XRF Scientific’s technical expertise, calibration support, and practical application knowledge. Contact XRF Scientific today to discuss your production requirements and locate the ONH analyzer that best supports your quality control objectives.