| Title |
A Comprehensive Review of Hydrogen Embrittlement Testing Methods and Standards for Steels |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.4.331 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Hydrogen embrittlement; Testing methods; Standards; Steel; Slow strain-rate test (SSRT); Notched tensile; In situ testing |
| Abstract |
The widening use of hydrogen energy infrastructure has increased concern about the hydrogen
embrittlement (HE) resistance of metallic materials, a critical property throughout the entire lifecycle of design,
manufacturing, and certification. HE arises from the coupled interaction of hydrogen ingress, diffusion, trapping,
and stress/strain fields. This makes direct comparison of results difficult due to variations in testing methods,
including hydrogen charging modes (electrochemical/high-pressure gas), hydrogen retention during testing (in
situ/ex situ), loading configurations (monotonic/sustained/cyclic), specimen geometries (smooth/notched/precracked),
and data reduction procedures. In particular, slow strain-rate tests (SSRT), notched tensile tests,
sustained load delayed fracture tests, and incremental step loading (ISL) tests can efficiently assess crack
initiation and time-delayed fracture susceptibility, while fracture toughness (K or J) and fatigue crack growth
rate (da/dN?ΔK) tests provide data about crack propagation-based design properties that are directly applicable
to defect-tolerant design and life assessment. This review systematically classifies HE evaluation test methods
for steels from the perspective of hydrogen introduction?loading mode?crack process (initiation/propagation),
and compares the physical meaning and applicability of quantitative metrics provided by each test. Furthermore,
the ISO/ASTM standardization framework is organized from the viewpoint of ‘procedural standards
(reproducibility)’ versus ‘design property standards (transferability)’. Then the influence of key governing factors
including stress state (constraint/triaxiality), hydrogen concentration (absolute amount/distribution/trapping),
strain rate and frequency, temperature and pressure, microstructure, and alloying elements is comprehensively
discussed. Finally, test selection strategies tailored to the objectives of material screening, design data
acquisition, and process quality control are proposed, along with minimum reporting requirements, providing
guidance to enhance the reliability and engineering utility of HE data. |