LAB cold rolling and annealing

LAB cold rolling and annealing - Electrical and thermal...

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Edge Dislocation Extra half plane of atoms Note : the dislocation line extends out of the screen . C T
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Cold Working “Strain Hardening” Plastic deformation exponentially increases Dislocation Density: a. New dislocations formed b. Dislocations get closer c. Strain interaction are repulsive More obstacles to interfere with slip “Forest of Dislocations”
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No Cold Work Cold worked/Strain Hardened
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Effect of Cold Work on the Stress vs. Strain curve
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Effects on Mechanical Properties Cold Working
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TS(psi) = 500 X HB TS(Mpa) = 3.45 X HB
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Definitions Annealing : A generic term used to denote a heat treatment wherein the microstructure and, consequently, the the properties are altered. Typically, used when heat treating a cold worked material thus causing it to recrystallize. Recovery Recrystallization Grain Growth
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No Cold Work Cold worked/Strain Hardened 33% Cold Worked
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Recovery Relief of some of the stored internal strain energy of a previously cold-worked metal Driving force: Stored internal strain energy
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Unformatted text preview: Electrical and thermal properties restored 3 sec @ 580 C 4 sec @ 580 C 8 sec @ 580 C CW 33% 100% recystallized. .this is not the recystallization temp The formation of a new set of grains within a previously cold worked material; normally by an annealing heat treatment • Driving force: Stored internal strain energy • New strain-free equiaxed grains formed through short range diffusion • Dependent on time, temperature, and % CW • Restores pre-cold worked mechanical properties Recrystallization 10 min @ 700 C 8 sec @ 580 C 15 min @ 580 C • Increase in the average grain size of a polycrystalline material • Elevated temperature • Driving force: reduction of energy associated with grain boundary area • Lowers strength and toughness Grain Growth 100% Recrystallized 33% Cold Worked Grain Growth Begins Recrystallization starts Effects on Mechanical Properties Time or Temp (horizontal axis) Process Annealing Bicycle wheel spoke manufacturing...
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This note was uploaded on 04/07/2010 for the course MAT SCI n/a taught by Professor N/a during the Spring '10 term at West Point.

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LAB cold rolling and annealing - Electrical and thermal...

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