Grain-Boundary Sliding
Definition
Relative motion of adjacent grains along their shared boundary, a key deformation mechanism at elevated temperature that opens voids at triple points and eventually leads to intergranular creep fracture.
- Mechanism type
- Deformation along adjacent grain boundaries
- Condition
- Occurs at elevated temperature
- Effect
- Opens voids at triple points
- Outcome
- Leads to intergranular creep fracture
Common questions
How is grain-boundary sliding recognised on a fracture surface?+
It leaves an intergranular fracture surface where the crack path follows the boundaries between grains rather than cutting through them, often visible under SEM as a faceted texture with cavities clustered at triple points where three grains meet.
Why does this mechanism matter in a failure investigation?+
Finding grain-boundary sliding and associated triple-point voids tells the investigator the component failed by creep at sustained high temperature and load, distinguishing it from a fast fracture caused by overload or fatigue at ambient conditions.
Related terms
- Creep
- Time-dependent plastic deformation of a material under sustained stress at elevated temperature, occurring at stress levels below the conventional yield strength.
- Hot Corrosion
- Accelerated degradation of a superalloy or coated turbine component by molten sulfate or vanadate deposits that flux and dissolve the protective oxide...
- Larson-Miller Parameter (LMP)
- A temperature-time combination parameter T(C + log t_r) used to correlate and predict rupture life across different temperature-stress combinations for a given...
- Minimum Creep Rate
- The steady-state strain rate during secondary creep, the single most important material parameter for structural life assessment under creep conditions.
- Reheat Cracking
- Intergranular cracking in the heat-affected zone of welds in certain alloy steels during post-weld heat treatment or early elevated-temperature service, caused by...