Hydrogen Embrittlement Test — ASTM F519 / ASTM F1624 / ISO 7539-11

What Is Hydrogen Embrittlement?

The hydrogen embrittlement test assesses whether hydrogen absorbed into the material during coating or acid cleaning causes delayed fracture under sustained load. The sustained-load method on a notched sample is common.

Purpose of Hydrogen Embrittlement

The purpose is to prevent the risk of sudden hydrogen-induced fracture in high-strength fasteners and coated parts, and to verify the adequacy of the coating process and stress-relief bake.

Which Products Is Hydrogen Embrittlement Applied To?

High-strength bolts and fasteners
Electroplated steel parts
Aerospace structural fasteners
Spring steels

In Which Sectors Is Hydrogen Embrittlement Used?

AutomotiveMetalSteelConstructionMaritime

Standards Related to Hydrogen Embrittlement

ASTM F519
ASTM F1624
ISO 7539-11
ASTM B850
ASTM B117tuz sisi (salt spray) korozyon testi test
ISO 9227tuz sisi korozyon testi test
ASTM G85modified salt fog (cyclic) test test
ASTM G48pitting and crevice corrosion in stainless steels test
ISO 16701cyclic corrosion test test
ISO 6270strength in condensation environment test
SAE J2334cyclic laboratory corrosion testing test
VDA 233-102cyclic corrosion testing in automotive test

Hydrogen Embrittlement Conditions

Loading: Constant load on a notched sample at a defined percentage of the breaking load in ASTM F519
Time: Typically 200 hours continuous load in ASTM F519
Environment: Room temperature or environment defined in the specification
Gerilim giderme: It is recorded whether or not a baking process is applied after coating.

Equipment for Hydrogen Embrittlement

Sustained-load test frames
Calibrated load cells
Notched-sample machining bench
Coating line (for process evaluation)

Sample Requirements for Hydrogen Embrittlement

Notched sample types defined in ASTM F519 are used
Samples must go through the actual coating process
Reference (uncoated) samples must also be tested
The number of specimens is defined in the standard

Duration of Hydrogen Embrittlement

Sustained-load duration is typically 200 hours; with preparation and coating, two weeks are planned.

Hydrogen Embrittlement Procedure

1Notched samples are machined and fracture load determined.
2Samples go through the coating process to be evaluated.
3Stress-relief baking is applied if required.
4Samples are loaded at the defined percentage of load.
5Whether fracture occurs is monitored over 200 hours.
6The surface of fractured samples is examined.

Hydrogen Embrittlement Acceptance Criteria

The acceptance criterion is defined in the standard: samples must not fracture during the defined load and duration. If fracture occurs, the coating process or stress-relief bake is deemed inadequate.

Evaluation of Results

Time to fracture and fracture-surface morphology are assessed. Hydrogen-induced fracture typically has a brittle appearance.

Hydrogen Embrittlement Report

Applied standard and sample type
Coating process and stress-relief conditions
Applied load and duration
Whether fracture occurred and its time
Fracture-surface images

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Aviation fastener specifications
High-strength bolt standards

Corrosion Tests — What Does This Testing Field Cover?

The section below describes the field that the Hydrogen Embrittlement test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Corrosion testing assesses under accelerated conditions how long metals and coatings last in a corrosive environment. The family contains two approaches, and the difference between them is the most important knowledge in the field: constant-condition tests and cyclic tests.

Constant-condition salt spray (ASTM B117, ISO 9227) maintains the same environment in the chamber throughout: the same salt concentration, the same temperature, a continuously wet surface. The strength of this approach is its REPEATABILITY; because the conditions are tightly defined, results from different laboratories come out close to one another. That is exactly the property wanted when monitoring production consistency and comparing suppliers.

But the real atmosphere is not constant. A surface gets wet, dries, warms, cools, takes UV and becomes soiled. The wet-dry cycle changes the corrosion mechanism: during drying the salt concentrates, oxygen access increases and corrosion accelerates. The form of damage on a continuously wet surface differs from that on a cyclically wetted one.

Cyclic tests (SAE J2334, VDA 233-102, ASTM G85, ISO 16701) imitate this variability and give results closer to the damage patterns seen in the field. The automotive sector has largely moved to this approach. The practical consequence is this: the same two coatings may RANK DIFFERENTLY in constant and cyclic tests; which test was applied determines the result.

No test in this family defines a DURATION OR ACCEPTANCE CRITERION. How many hours it is applied for and what level of damage is acceptable come from the product standard or the customer specification. The assessment scales are defined in separate standards: different scales are used for degree of rusting, blistering, creep from a scribe and loss of adhesion.

The damage looked for varies with the coating type. For metallic coatings, white rust (corrosion of the coating itself) and red rust (corrosion reaching the base metal) are reported separately, and specifications usually give a separate duration for each. On painted surfaces, creep from a scribe and blistering come to the fore.

Electrochemical methods are a separate body of work and answer a different question. Potentiodynamic polarisation, electrochemical impedance spectroscopy and pitting potential measurements reveal the MECHANISM and rate of corrosion within hours; chamber tests give the result visually over weeks. The two are complementary rather than alternatives.

Stainless steels have a special sub-body in the field: pitting and crevice corrosion and intergranular corrosion tests indicate the quality of the heat treatment and the condition after welding.

Method groups in this field

Constant-condition salt spray
ASTM B117 and ISO 9227 (NSS); for repeatable comparison and process control.
Acidified and accelerated
The AASS and CASS conditions of ISO 9227; preferred for decorative chromium-nickel coatings.
Cyclic corrosion
SAE J2334, VDA 233-102, ASTM G85 and ISO 16701; approaches field behaviour through wet-dry cycles.
Humidity and condensation
Steady damp heat, condensation and cyclic humidity tests; these reveal coating blistering.
Electrochemical
Polarisation, impedance spectroscopy, pitting and crevice corrosion potential measurements.
Stainless steel specific tests
Pitting and crevice corrosion, intergranular corrosion; indicators of heat treatment and weld quality.
Assessment scales
Scales for degree of rusting, blistering, creep from a scribe and loss of adhesion; the ratings come from these standards.

Commonly confused in this field

Chamber hours cannot be converted into field life; there is no reliable conversion factor.
Constant and cyclic tests can produce different rankings; whichever the specification states is the one applied.
A corrosion report without a stated duration and acceptance criterion cannot be interpreted.
If the coating thickness is not reported, the result cannot be compared; thickness directly affects durability.
White rust and red rust say different things; the two must be reported separately.
The position and angle of the specimen in the chamber affect the result; standards govern this and the report must document it.

Which decisions these results support

Selection of the coating system and supplier approval
Process control of the coating line and lot acceptance
Evidence of durability for automotive and outdoor products
Assessment of field corrosion damage and warranty decisions
Verification of heat treatment and weld quality in stainless steel

Related Tests

Frequently Asked Questions About Hydrogen Embrittlement

Why is stress-relief baking important?

Post-coating baking is applied to drive out hydrogen absorbed into the material during electroplating. If this is skipped or delayed, the risk of delayed fracture in high-strength parts increases.