Measuring hydrogen permeation according to ASTM G148

Importance of the Topic

Hydrogen permeation into metals is a critical issue in electroplating, corrosion science and cathodic protection studies. Accumulation of hydrogen can embrittle materials, reduce mechanical strength and provoke cracking, making reliable measurement of hydrogen uptake and diffusion essential for industrial and research applications.

Study Objectives and Overview

This work demonstrates an electrochemical approach to quantify hydrogen permeation through 316L stainless steel foil in accordance with ASTM G148. Dual potentiostat/galvanostat instruments are employed to generate hydrogen on one side of an H-cell and detect its passage on the opposite side, enabling time‐resolved monitoring of hydrogen transport.

Methodology and Instrumentation

The experimental setup comprises an H-cell divided into charging and detection compartments by a shared 50 µm thick 316L steel foil (1.8 cm2 exposed area each side). Key elements:

• Hydrogen generation (charging side): galvanostatic mode at –1 mA/cm2 applied to the working electrode in 1 M HCl containing 0.25 g/L Na2HAsO4·7H2O, counter electrode: platinum sheet.
• Hydrogen detection (oxidation side): potentiostatic mode at +300 mV vs. OCP in 0.1 M NaOH, reference: Ag/AgCl (3 M KCl), counter: platinum sheet.
• Two VIONIC powered by INTELLO instruments operated in floating mode share the working electrode without a direct ground connection.
• No deaeration of solutions was performed.

Main Results and Discussion

Upon initiating +300 mV on the detection side, the oxidation current decays as polarization relaxes. Addition of the acidic solution at ≈2700 s triggers hydrogen evolution on the charging side, observed as a small current perturbation. At ≈2800 s, permeated hydrogen arrives at the detection compartment and oxidizes, causing a distinct rise in current. Figure 1 depicts the dual VIONIC instruments in floating mode. Figure 2 illustrates the oxidation current vs. time profile, highlighting the induction period and subsequent permeation signal.

Benefits and Practical Applications

This electrochemical permeation method offers:

• Quantitative, time‐resolved evaluation of hydrogen uptake and diffusion.
• Compatibility with standard ASTM G148 protocols.
• Flexibility to study coatings, inhibitors or alloy variations under realistic conditions.

Future Trends and Potential Applications

Advancing this approach may involve integration with high‐frequency electrochemical impedance spectroscopy to probe interface kinetics, extension to other alloys or composite materials, and coupling with computational models to predict hydrogen transport and damage thresholds.

Conclusion

The described ASTM G148‐based protocol successfully quantifies hydrogen permeation through stainless steel using dual VIONIC/INTELLO potentiostats. The method delivers clear detection of hydrogen transit and supports diverse corrosion and materials‐performance studies.

Instrumentation

Major equipment:

• VIONIC powered by INTELLO potentiostat/galvanostats (±50 V, ±6 A, EIS up to 10 MHz)
• 316L stainless steel foil working electrode (50 µm, 1.8 cm2 per side)
• Platinum sheet counter electrodes
• Ag/AgCl reference electrode (3 M KCl)

References

• ASTM G148 – Standard Practice for Evaluation of Hydrogen Uptake, Permeation, and Transport in Metals by an Electrochemical Technique
• Charca, S. M. Study of Hydrogen Permeation and Diffusion in Steels: Predictive Model for Determination of Desorbed Hydrogen Concentration. University of Puerto Rico Mayagüez, 2006.