What is the difference between intergranular cracking, transgranular cracking, and intercrystalline cracking?

**Intergranular cracking **primarily occurs at the boundaries between grains; that is, the cracks propagate along the contact surfaces between grains. Such cracks do not penetrate through the interior of the grains, but rather surround the edges of the grains. **Transgranular cracking** occurs when the crack propagates directly through the interior of the grain, passing through the entire grain. This type of crack does not stop or change direction at the grain boundaries. **Grain-edge cracking **is a phenomenon similar to intergranular cracking; the cracks propagate primarily along the grain boundaries, but they may also extend into parts of the grains themselves. Grain-boundary cracking and intergranular cracking may be considered the same type in some literature. In summary, the main difference lies in the path of crack propagation: intergranular cracking is confined to the grain boundaries, whereas transgranular cracking extends through the interior of the grains. Grain-boundary cracking falls between the two. .