Hydrogen embrittlement

Hydrogen embrittlement is the loss of ductility and fracture resistance when hydrogen enters a metal. It can cause delayed cracking under tensile stress, sometimes at loads below the metal’s usual strength.

Hydrogen-enhanced localized plasticity: A proposed mechanism in which hydrogen increases dislocation mobility and concentrates plastic deformation in metals. It explains how hydrogen can localize deformation before a crack forms.
Hydrogen storage: The containment of hydrogen in forms suitable for transport, storage, or use. Storage vessels and pipelines must resist hydrogen-assisted cracking during service.
Stress corrosion cracking: Crack growth caused by the combined action of tensile stress and a corrosive environment. It can resemble hydrogen embrittlement, though the environment and crack-growth mechanisms differ.
Hydrogen permeation: The entry, diffusion, and exit of hydrogen through a material, commonly measured as a transport process. Permeation connects hydrogen exposure at a surface to internal metal concentrations.
NACE TM0177: A standard test method for evaluating sulfide stress cracking and stress corrosion cracking of metallic materials in sour environments. Its procedures assess cracking susceptibility in environments that can charge steel with hydrogen.
Hydrogen-enhanced decohesion: A proposed mechanism in which hydrogen lowers the atomic cohesion of a metal, promoting separation along interfaces or planes. It accounts for hydrogen-assisted cracking through weakened atomic bonds.
Hydrogen pipeline: A pipeline designed to transport hydrogen gas, either pure or blended with other gases. Hydrogen exposure can reduce the fracture resistance of pipeline steels.
Liquid metal embrittlement: Loss of ductility when a solid metal is exposed to a contacting liquid metal under stress. It is another environment-assisted form of brittle failure, but involves liquid-metal contact.
Hydrogen trap: A defect or microstructural feature that binds hydrogen and changes its mobility or availability in a metal. Traps can either immobilize hydrogen or supply it to developing cracks.
ASTM F1624: A test method for measuring threshold stress intensity and time-to-failure behavior in metallic materials susceptible to hydrogen embrittlement. It quantifies delayed failure thresholds in high-strength materials.

Linked from 12 pages