Bulk deformation

?
What is “work hardening” (or strain hardening)? Why does it occur?
Is a permanent deformation induced in a metal, raising the yield strength beyond the properties of a deformed shape. The overall effects make the finished part stronger as it receives no further plastic deformation
1 of 17
Under which of these conditions could work hardening occur: Cold working, warm working, hot working?
Yes for cold and hot as hardening occurs because no recrystilllisation takes place. Hot working doesn't because the temperature is above recrystallisation temp.
2 of 17
What is the main advantage of work hardening?
Stronger parts
3 of 17
What are some disadvantages of work hardening?
Reduces ductility, more rapid failure, mechanical properties are less easy to predict
4 of 17
How does increasing temperature affect the strength and ductility properties of a metal?
Yield and ultimate strength not decrease with increasing temp. Ductility increases.
5 of 17
What is the recrystallisation temperature?
The temperature where a a new crystal structure forms. Approx half of the metals temprature.
6 of 17
Indicate some of the advantages of cold working relative to warm and hot working.
Better accuracy, Better surface finish, increase in strength due to work hardening, possible directional properties due to grain flow, no heating work required
7 of 17
Indicate some of the advantages of hot working relative to cold and warm working.
Work piece can be altered, lower forces and power required, metals that usually fracture in cold working can be formed, strength properties are generally isentropic, no strentghing of part occurs from work hardening
8 of 17
What are the reasons why the bulk deformation processes are important commercially and technologically?
Capable of significant shape change, positive effect on part strength, little material waste
9 of 17
Name the three key bulk deformation processes (not including wire and bar drawing). Draw a simple sketch that illustrates the fundamental operation in each.
Rolling, forging, extrusion
10 of 17
Describe rolling in the context of the bulk deformation processes?
Rolling is where a workpiece is rolled by two compressive forces
11 of 17
List some of the products produced on a rolling mill
Flat sheet, plate sock, rods
12 of 17
What is forging?
Forging is a deformation process where the workpiece is compressed between two dies
13 of 17
One way to classify forging operations is by the degree to which the work is constrained in the die. By this classification, name the three basic types.
Open die, impression die, fleshless forging
14 of 17
What is a trimming operation in the context of impression die forging?
Triming is used to remove the flash on the workpiece
15 of 17
What are the two basic types of forging equipment?
Hammers and presses
16 of 17
What is extrusion?
Extrusion is a compression forming operation in which a workpiece is forced to flow through a die opening
17 of 17

Other cards in this set

Card 2

Front

Under which of these conditions could work hardening occur: Cold working, warm working, hot working?

Back

Yes for cold and hot as hardening occurs because no recrystilllisation takes place. Hot working doesn't because the temperature is above recrystallisation temp.

Card 3

Front

What is the main advantage of work hardening?

Back

Preview of the front of card 3

Card 4

Front

What are some disadvantages of work hardening?

Back

Preview of the front of card 4

Card 5

Front

How does increasing temperature affect the strength and ductility properties of a metal?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Engineering resources:

See all Engineering resources »See all Thermo resources »