Overview
ISO 16573-2:2022 specifies a laboratory method to evaluate hydrogen embrittlement (hydrogen delayed fracture) resistance of high‑strength, ferritic steels using the Slow Strain Rate Test (SSRT) on hydrogen pre‑charged specimens. The standard combines controlled hydrogen charging, tensile testing at slow strain rates, and thermal desorption analysis (e.g., gas chromatography or mass spectrometry) to quantify diffusible hydrogen and relate it to degradation of mechanical properties (yield strength, tensile strength, elongation, reduction of area).
Key topics and technical requirements
- Test principle: measure mechanical properties before and after hydrogen pre‑charging; quantify absorbed hydrogen by thermal desorption and correlate hydrogen content with property loss.
- Specimens: both cylindrical (typical diameter 10 mm; smaller sizes permitted) and flat specimens (10 mm grip width recommended) with smooth or notched gauge sections are covered.
- Hydrogen charging methods:
- Cathodic (electrochemical) pre‑charging with defined charging solutions and controlled current density and time (recommended charging time examples included).
- Absorption from aqueous corrosion at free corrosion potential (e.g., HCl), atmospheric corrosion (salt spray / cyclic corrosion tests), and high‑pressure hydrogen gas (not recommended routinely for safety reasons).
- Plating to retain hydrogen: post‑charging electroplating (e.g., Cd or alternatives such as Zn) is recommended to prevent hydrogen escape during testing; note that Cd is toxic and requires special handling.
- Slow strain rate test: procedures for test setup, loading at slow strain rates, result presentation and comparison across materials are specified.
- Hydrogen thermal desorption: protocols for quantitative analysis using gas chromatography or mass spectrometry, and guidance on sampling pre‑charged and post‑deformation specimens.
- Reporting: required test report items and data presentation to enable comparison of hydrogen embrittlement susceptibility.
Applications and who should use this standard
ISO 16573-2 is intended for:
- Materials and metallurgical engineers assessing hydrogen embrittlement susceptibility of high‑strength ferritic steels
- Mechanical testing laboratories and quality assurance groups validating components for automotive, aerospace, oil & gas, and hydrogen‑service applications
- R&D teams comparing microstructures, heat treatments, coatings, or alloying effects on hydrogen resistance
- Designers and procurement specialists specifying test requirements for components expected to encounter hydrogen environments
Practical benefits include reproducible evaluation of diffusible hydrogen effects, basis for material selection, and verification of mitigation measures (coatings, processing).
Related standards
Keywords: hydrogen embrittlement, slow strain rate test, thermal desorption analysis, hydrogen pre‑charging, high‑strength steels, ferritic steels, gas chromatography, mass spectrometry, cathodic charging.