ISO 17081:2014

Overview

ISO 17081:2014 - Method of measurement of hydrogen permeation and determination of hydrogen uptake and transport in metals by an electrochemical technique - specifies a laboratory electrochemical method to measure hydrogen permeation, hydrogen uptake, and hydrogen transport in metals and alloys. The standard describes how to generate hydrogen at a charging face, monitor the oxidation (permeation) current on the opposite face, and analyze the resulting permeation transient to obtain steady-state fluxes and transport properties.

Key topics and technical requirements

• Principle: Hydrogen atoms generated on the charging side diffuse through the metal and are oxidized on the oxidation side. The oxidation (permeation) current is monitored as a function of time.
• Measured outputs: steady-state hydrogen flux (Jss), permeation current, lag time (tlag), and effective diffusivity (Deff). Analysis is based on diffusion theory (Fick’s second law) and transient/permeation-current analysis.
• Trapping: Procedures to distinguish reversible and irreversible hydrogen traps and to evaluate their influence on transport and uptake.
• Specimen preparation: Requirements for sample geometry and orientation (plate or pipe), thickness selection to ensure one-dimensional diffusion, and recommended radius:thickness ratios (e.g., 10:1 recommended; less stringent options when oxidation area is reduced).
• Surface treatments: Use and implications of palladium coatings (can aid gaseous charging and oxidation kinetics but may affect sub-surface concentrations).
• Test environment control: Detailed requirements for charging environments (aqueous or gaseous), electrode potentials on the oxidation side (to ensure transport-limited oxidation), and monitoring of background currents.
• Apparatus and procedure: Guidance on charging cells, oxidation cells, instrumentation for current/time recording, and analysis of both steady-state and transient data.
• Reporting: Required test report elements including material form, sample orientation, test conditions and environmental variables.

Practical applications and typical users

ISO 17081:2014 is used to:

• Quantify hydrogen uptake and rank the relative aggressivity of environments toward hydrogen absorption.
• Determine hydrogen diffusivity and evaluate susceptibility to hydrogen-assisted damage (e.g., hydrogen embrittlement) in metals and alloys. Typical users include materials engineers, corrosion scientists, failure analysts, laboratory technicians, and R&D teams in sectors developing or qualifying metallic components for hydrogen service (metallurgy, energy/hydrogen systems, transport, pressure equipment).

Related standards

• ISO 17475 - Corrosion of metals and alloys - Electrochemical test methods - Guidelines for potentiostatic and potentiodynamic polarization measurements.
• ISO 17081 was prepared under ISO/TC 156 (Corrosion of metals and alloys).

Keywords: ISO 17081:2014, hydrogen permeation, hydrogen uptake, electrochemical technique, hydrogen transport, permeation current, diffusivity, hydrogen trapping, permeation transient, specimen preparation.