An intergranular fracture is a fracture that follows the grains of the material. If the material has multiple lattice organizations, when one lattice ends and another begins, the fracture changes direction to follow the new grain. This results in a fairly jagged looking fracture with bumpy edges.
Intergranular fractures are cracks that take place along the grain boundary of a material. Straight edges of the grain and shiny surface may be seen. There are several processes that can lead to intergranular fracture.
- Microvoid nucleation and coalescence at inclusions or second phase particles located along grain boundaries
- Grain boundary crack and cavity formation associated with elevated temperature stress rupture condition.
- Decohesion between contiguous grain due to presence of impurity at grain boundaries and in the presence of hydrogen and liquid metals.
- Stress corrosion cracking associated with chemical dissolution along grain boundaries.
- Cyclic loading when the material insufficient number of independent slip systems to accommodate plastic deformation between contiguous grain leading to grain boundaries.
Think of several wooden jigsaw puzzle pieces with the grains showing, but with each piece having grains running in a different direction.An intergranular fracture follows the edges of the puzzle pieces, ignoring the grains in the wood.
This is opposed to a Transgranular fracture.