Damage in which atomic hydrogen, generated by corrosion, cathodic protection, pickling or electroplating, diffuses into steel and cuts its ductility and toughness. High-strength steels, roughly above 1000 MPa tensile strength, are the most vulnerable, and fasteners can crack hours or days after they are loaded. Excessive CP potentials on high-strength steel and plated bolts that were never baked are the classic causes.
Those plated bolts snapped two days after torquing, smells like hydrogen embrittlement, ask if they were baked.
Electroplated high-strength fasteners need a bake soon after plating to drive the hydrogen out, so ask for the bake record.
Also heard as
- HE
- hydrogen-assisted cracking
- HAC
Related terms
Sulfide stress cracking
Cracking of hard steel under tension in wet hydrogen sulfide service, a form of hydrogen embrittlement.
Overprotection
So much cathodic current that potentials get too negative, risking coating damage and hydrogen problems.
SCC
Stress corrosion cracking: brittle cracking caused by tensile stress acting together with a specific corrosive environment.