Recrystallization Theoretical & Practical Aspects - Materials Science ...

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Intro <strong>Recrystallization</strong> Lab 1 Grain Boundaries <strong>Recrystallization</strong> Characteristics • In order for the boundary between a new grain (nucleus) and the deformed material to be able to move, it must be a high angle boundary. This is a consequence of the properties of boundaries, to be described later. • The requirement that new grains have high angle boundaries means that the final grain size and the rate at which recrystallization takes place is highly dependent on the strain level. • Higher strains mean greater lattice rotations (from dislocation slip) inside grains and higher stored energies. Therefore the probability of generating new grains increases with strain and the driving force increases. • Increasing probability for nucleation translates directly into increased density of nuclei and therefore smaller recrystallized grain size. 8
Grain size as a function of prior deformation level • The grain size after recrystallization decreases with increasing prior strain, i.e. the nucleation density increases. • Example of commercial purity Al, recrystallized at Intro 600°C (1.5h) after 2 (top), 6, Recryst- 8 & 10% (bottom) reduction allization in tensile strain. Lab 1 • Note that these are very small strains compared to Grain commercial practice. Boundaries • Next slide shows industrial data on grain size, also for commercial purity aluminum. 9
Page 1 and 2: Intro Recrystallization Lab 1 Grain
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Page 13 and 14: Intro Recrystallization Lab 1 Tempe
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Recrystallization Theoretical & Practical Aspects - Materials Science ...

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