Overview
ISO 16573-1:2020 - Steel - Measurement method for the evaluation of hydrogen embrittlement resistance of high strength steels - Part 1: Constant load test specifies a standardized laboratory method to evaluate resistance to hydrogen embrittlement (hydrogen delayed fracture) in high‑strength steels, primarily high‑strength steel bolts. The standard uses constant load testing on hydrogen‑charged specimens and quantifies absorbed hydrogen using thermal desorption analysis (e.g., gas chromatography, mass spectrometry). It also outlines procedures for hydrogen continuous charging (aqueous corrosion, atmospheric corrosion cycles, and high‑pressure hydrogen gas).
Key topics and requirements
- Test principle: Pre‑charge specimens with hydrogen or load them under continuous charging, apply a constant tensile load, and record time‑to‑failure to relate diffusible hydrogen content to susceptibility.
- Specimen geometry: Typical specimen diameter is 10 mm with notched and smooth configurations illustrated; smaller diameters (5 mm) are addressed with adjusted notch radii.
- Hydrogen charging methods:
- Cathodic (pre‑charging) - defined charging solutions and conditions; current density ranges (≈0–20 A/m²) and recommended charging times (commonly 48 h; total 72 h when including post‑treatments) are given to control hydrogen uptake.
- Continuous charging - procedures for immersion in acidic solutions at free corrosion potential, cyclic atmospheric corrosion tests (salt spray / drying / humidifying), and exposure to high‑pressure H2 (noting safety concerns).
- Electroplating / sealing: Post‑charge plating (Cd historically, Zn as alternative) to prevent hydrogen loss during testing; solution compositions and plating conditions (e.g., example current/time) are included. Note: Cd is toxic and requires regulatory controls.
- Hydrogen analysis: Thermal desorption analysis (TDA) using gas chromatography or mass spectrometry to quantify diffusible hydrogen after testing.
- Data & reporting: Guidance on presenting time‑to‑failure curves vs. hydrogen content and required test report elements.
Applications and users
ISO 16573-1:2020 is used for:
- Comparative evaluation of hydrogen embrittlement resistance among high‑strength steels and bolt materials.
- Qualification and materials selection in industries sensitive to hydrogen effects: automotive, aerospace, oil & gas, fastener manufacturing, and heavy machinery.
- Materials testing laboratories, R&D groups, quality assurance teams, and standards bodies conducting reproducible hydrogen embrittlement testing and hydrogen quantification.
Keywords: ISO 16573-1:2020, hydrogen embrittlement, constant load test, high strength steel bolts, hydrogen pre-charging, thermal desorption analysis, cathodic charging, diffusible hydrogen.
Related standards (if applicable)
- ISO technical committee guidance on steel testing; consult national standards bodies or ISO catalogue for related parts in the ISO 16573 series and complementary hydrogen testing standards (refer to ISO Online Browsing Platform for updates).