Annealing Processes in Metals Outline

Annealing Processes in Metals Outline - Annealing Processes...

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Annealing Processes in Metals Outline An Important Distinction: hot working and cold working does NOT rest with temperature alone. Cold working can happen at temperatures as high as 3000 degrees Celsius. Hot working can occur at room temperature. It depends on the material! Cold Working A. What gets cold worked? What causes cold working? a. Only metals and alloys get cold worked. Ceramics are too brittle to be. b. Cold working is the altering of the shape and/or size of a metal by plastic deformation i. Examples of this include rolling, drawing, elongation in tension c. Amount of cold working is expressed in terms of: i. % elongation in tension test ii. % RA of cross-section in rolling or wire-drawing B. Effects of Cold Working a. Increase in strength, but a reduction in Ductility of the metal i. Strength can be doubled for large amounts of cold work b. The production of preferred orientation of the grains, especially with increased amounts of cold- working i. Grains elongated in the “working direction” c. An increase in stored energy in the form of lattice distortions. These distortions lead to an increase in dislocations and vacancies i. The increase in strength is largely due to the increase of dislocations 1. dislocation density can be raised from 10^6 lines/sq. meter to 10^13 lines/sq. meter. C. Cold Working Efficiency a. Only 5-10% of energy stored in the metal is put into producing dislocations i. The remaining energy is converted to heat b. Even with low efficiency, cold working can be the “driving force” for changes that occur during annealing
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The Annealing Process: Reversing Cold Work A. Important Definitions c. Annealing- the heating of material for a certain period of time in order to change
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This note was uploaded on 03/31/2008 for the course MATERIAL S 350 taught by Professor Samuel during the Fall '07 term at Wisconsin.

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Annealing Processes in Metals Outline - Annealing Processes...

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