Grain Boundary Strengthening
Where a buildup of dislocations at a grain boundary causes a repulsive force between dislocations. As grain size decreases, the surface area to volume ratio of the grain increases, allowing more buildup of dislocations at the grain edge. Since it requires a lot of energy to move dislocations to another grain, these dislocations build up along the boundary, and increase the yield stress of the material. Also known as Hall-Petch strengthening, this type of strengthening is governed by the formula:
where
- is the stress required to move dislocations,
- k is a material constant, and
- d is the grain size.
Read more about this topic: Yield (engineering), Factors Influencing Yield Stress, Strengthening Mechanisms
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