Chapter 7
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Chapter 7. Effects of Plastic Deformation and Heat. Plastic Deformation and Structure • Plastic Deformation and Mechanical Properties • Heat, Structure, and Mechanical Properties.

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Chapter 7

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Chapter 7

Chapter 7

Effects of Plastic Deformationand Heat

Plastic Deformation and Structure • Plastic Deformation and Mechanical Properties • Heat, Structure, and Mechanical Properties


Chapter 7

During slip, one part of a metal crystal undergoes a shear displacement relative to another that preserves the crystal structure of the metal.


Chapter 7

When a metal undergoes plastic deformation, certain parallel crystallographic planes undergo slip. The bulk of the material between the planes retains its original crystallographic orientation.


Chapter 7

Slip bands change direction at the grain boundary because each grain has a different crystallographic orientation.


Chapter 7

To calculate the resolved shear stress acting on a set of crystallographic planes, the force applied is resolved into two components (parallel and perpendicular to the slip planes).


Chapter 7

FCC metals have 12 slip systems, consisting of four (111) slip planes multiplied by three 〈110〉 slip directions.


Chapter 7

Individual crystals tend to rotate under an applied force, so that the crystallographic planes move into the most favorable orientation for slip.


Chapter 7

Slip originates in the grains with slip systems most favorably oriented (45°) to the direction of the applied force.


Chapter 7

The crystal structure of a metal is preserved during mechanical twinning.


Chapter 7

Slip appears as slip bands and mechanical twinning appears as bands in the microstructure.


Chapter 7

Point defects include vacancies and interstitial atoms.


Chapter 7

The movement of each atom during slip can be illustrated by describing the resisting force associated with sliding a heavy rug across a floor.


Chapter 7

Edge dislocation is characterized by the Burgers vector, which is obtained by enclosing the dislocation in an atom-by-atom path and measuring the change in distance and direction from the starting position.


Chapter 7

The mechanism of slip caused by movement of an edge dislocation greatly lowers the stress required for slip.


Chapter 7

The path taken around the axis of the screw dislocation is a helix.


Chapter 7

The boundary between the slip region and the region without slip is perpendicular to the axis of an edge dislocation and parallel to the axis of a screw dislocation.


Chapter 7

Stacking faults are most common in close-packed planes of atoms.


Chapter 7

With increased cold working or reduction of cross-sectional area, the grains elongate in the direction of cold working.


Chapter 7

The increase in strain hardening is the result of the increase of cold working.


Chapter 7

Annealing refers to a variety of specific heat treatment processes.


Chapter 7

Stress-relieving temperature ranges vary for different types of alloys.


Chapter 7

The percent residual stress removed is related to the stress-relieving temperature and the time at temperature.


Chapter 7

Sharp changes in mechanical properties are exhibited during recrystallization.


Chapter 7

Recrystallization requires an incubation period to initiate the process.


Chapter 7

Recrystallization temperature and recrystallized grain size fall to minimum values with increasing amounts of cold working.


Chapter 7

A stacking fault formed after annealing of certain cold-worked FCC metals leads to the formation of an annealing twin (mirror images).


Chapter 7

Amounts of grain growth increase with increasing temperature and time at temperature. As both increase, grain growth will eventually stabilize.


Chapter 7

Critical strain produces abnormal grain growth in a material.


Chapter 7

Hot working is plastic deformation by controlled mechanical operations performed above the recrystallization temperature of a material.


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