Hydrogen Embrittlement
Hydrogen embrittlement is the loss of ductility and load-bearing capacity of a metal caused by the absorption of atomic hydrogen, typically affecting high-strength steels, titanium alloys, and some nickel alloys.
Definition
Hydrogen sources include cathodic protection, electroplating, pickling acids, welding moisture, and wet H2S service. Prevention includes baking after plating, low-hydrogen welding processes, and material/hardness control per NACE MR0175. Related: HIC and SSC.
How this damage forms
Dissolved atomic hydrogen reduces a metal's ductility and its resistance to crack propagation, so a component that would have deformed instead fractures — often well below the stress it was designed for, and often after a delay while hydrogen diffuses to a stress concentration.
How it is detected
There is no NDT method that measures embrittlement directly. What is detected is the cracking that results, by magnetic particle or ultrasonic examination depending on location, and often after failure rather than before.
Why it gets missed
The susceptible-but-not-yet-cracked condition, which is the state anyone would actually want to find. This is why it is controlled by process rather than by inspection.
What causes it, and what prevents it
Control is preventive: baking after electroplating to drive hydrogen out, low-hydrogen consumables kept dry, preheat and controlled cooling in welding, and limits on cathodic protection potential. High-strength steels are the most vulnerable, and susceptibility rises sharply with hardness.
Codes that govern assessment
ASTM F1624 and ASTM F519 for susceptibility and process control testing; NACE MR0175 / ISO 15156 for hardness limits in sour service; API 571 for the mechanism in refinery equipment.
The common reporting error
Assuming a delayed failure was a manufacturing defect. Delayed cracking hours or days after load application is characteristic of hydrogen, and looking only for a pre-existing flaw misses the actual cause.
Where Hydrogen Embrittlement fits in an inspection programme
A term is only useful when it connects to a decision. Hydrogen Embrittlement appears in written procedures, in technique sheets, and in the records an owner or accreditation body reviews afterwards — which means the way it is defined in your documentation has to match the way it is applied on site. Where the two drift apart, audits find it. Atlantis writes and reviews procedures against the governing codes, trains inspection personnel to apply them, and builds the record-keeping that makes the evidence retrievable years later. Procedure development and code consulting · NDT training and certification · Ask us about your programme.
Related terms
- Hydrogen-Induced Cracking (HIC) — Hydrogen-induced cracking is a stepwise internal cracking in carbon and low-alloy steel pipelines and vessels exposed to wet H2S service, in which atomic hydrogen accumulates at inclusions and recombines, generating high internal pressure that causes blister-l
- Sulfide Stress Cracking (SSC) — Sulfide stress cracking is hydrogen-assisted brittle cracking of high-strength steels in wet H2S environments, principally affecting hardened steels above approximately 22 HRC such as fasteners, valve internals, and high-strength pipe.
- Stress Corrosion Cracking (SCC) — Stress corrosion cracking is the brittle cracking of a normally ductile material under the combined action of tensile stress and a specific corrosive environment, propagating along grain boundaries (intergranular) or through grains (transgranular).
Further reading
hydrogen assisted cracking in welds detection
More defect terms
Crack · Lack of Fusion · Lack of Penetration · Slag Inclusion · Porosity · Undercut · Overlap · Burn-Through · Weld Spatter · Lamination
Where this comes up in practice
Terms like this one appear in three places that matter commercially: the written practice that governs how your personnel are qualified, the procedures and technique sheets that define how an examination is actually performed, and the evidence an auditor or client asks for when they want to know why an inspection was accepted. Getting the terminology right is the easy part; being able to produce the qualification record, the calibration traceability and the procedure revision that applied on the day of the inspection is the part that decides audits.
Atlantis NDT provides NDT training and certification against ASNT SNT-TC-1A and ISO 9712, ASNT Level III consulting for written practices and procedure approval, inspection management software that holds qualification, calibration and procedure-revision evidence in recoverable form, and an asset integrity platform that binds inspection results to the asset they describe. Browse the full NDT glossary or ask a Level III directly.