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Flashcards in Chapter 17 Deck (12):

Define: Metal Forming

Includes a large group of manufacturing processes in which plastic deformation is used to change the shape of metal workpieces


Define: Deformation Processes

Generally characterized by significant deformations and massive shape changes:

- Rolling
- Forging
- Extrusion
- Drawing


Define: Bulk vs. Sheet

Bulk: the work parts that have low area-to-volume ratio

Sheet: The surface area-to-volume ratio is very high


Define: Rolling

Compressive deformation process in which the thickness of a slab or plate is reduced by two opposing cylindrical tools called rolls.


Define: Forging

A workpiece is compressed between two opposing dies, so that the die shapes are imparted to the work. Traditionally a hot working process, but sometimes done cold.


Define: Extrustion

Compression process in which the work metal is forced to flow through a die opening, thereby taking the shape of the opening as its own cross section.


Define: Drawing

The diameter of a round wire or bar is reduced by pulling it through a die opening.


Define: Stamping

A part produced from from sheet metal operations (press-working)


Define: Flow Stress

The strength property that determines forces and power required to accomplish a particular forming operation. Defined as the instantaneous value of stress required to continue deforming the material to keep the metal "flowing"


Define: Average Flow Stress

Average value of stress over the stress-strain curve from the beginning of strain to the final (maximum) value that occurs during deformation.. (Y = Ke^n) / (1+n)


Define: Cold vs. Warm vs Hot Working

Cold: is metal forming performed at room temperature or slightly above. Advantages - greater accuracy, better surface finish, high strength and hardness, no heating required

Warm: is metal forming above .3*T_melt. Advantages - lower forces and power, more intricate work geometries, and need for annealing.

Hot: Metal forming and deformation at temperatures above the re-crystallization temperature.


Define: Strain Rate Sensitivity

The effect of strain rate on strength properties. Strain rate is referred to as epsilon_dot and is deformation speed divided by instantaneous height of the workpiece.