Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Mat E 202 > Ch 7 > Flashcards

Ch 7 Flashcards

1
Q

Define annealing

(Two things)

A

Heat treatment process that reduces the effects of cold working and can restore the properties and dislocation structure to the pre-cold work state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Annealing can reverse the effects of what

A

Strain hardening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Three things annealing does

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of activated process is annealing and what does it involve?

A

Thermally activated process

Involves atomic rearrangement, especially with atoms, located in dislocations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

List the three stages of annealing in order

A

Recovery

Recrystallization

Grain growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the extent to which the properties changing each of the three stages of annealing

A

Recovery: minor changes in properties

Recrystallization: significant changes in properties

Grain growth: minor changes in properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the order of activation energy for each of the three stages of annealing

A

Recovery: smallest

Recrystallization: larger

Grain growth: largest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What two processes might not occur in annealing, and what always occurs

A

Green growth and recrystallization

Recovery always happens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the three vertical sections on this diagram?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe what happens to the grains during annealing

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define recovery

A

The relief of some of the internal strain energy of a previously cold worked metal, usually by heat treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In a light microscope is recovery visible

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define stress relief anneal

A

Reduces the internal residual stress is caused due to cold work (strain hardening)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Does a stress relief anneal result in significant property changes

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What phase of annealing does a stress relief anneal occur

A

Recovery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens during recovery?

A

Thermal energy added from heat, triggers, diffusion, and some dislocation motion can occur to either redo strain, energy, or reduce the number of dislocations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does equiaxed grain structure mean?

A

Grains with nearly equal dimensions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define nucleation

A

The initial stage in phase transformation

Evident by the formation of small particles (nuclei) of the new phase that are capable of growing

19
Q

Define recrystallization

A

Equiaxed grains nucleateand grow in the deformed (elongated) greens until these elongated grains have been totally replaced

20
Q

What does recrystallization reverse?

A

The effects of cold, working, or strain hardening

21
Q

During recrystallization what decreases in what increases

A

Strength decreases

Ductility increases

22
Q

When does the recovery stage occur?

(in terms of temp)

A

Occurs at lowest temp her first at higher temps

(since it has the lowest activation energy

23
Q

Stress relief anneal: what is retains and what is removed?

A

Strength is retained

Internal stresses are removed

24
Q

Is there any recrystallization during a stress relief anneal?

A

NO

25
Q

Recrystallization: will not occur unless what

A

A certain amount of %CW has been done

(About 2-20%, about 5% for iron)

26
Q

Recrystallization: what happens if you plot % completion versus log t

A

You get sigmoidal (S shaped curves)

27
Q

Recrystallization: what does a higher temperature mean?

A

Faster reaction

Small drop in temperature means large increase in time

28
Q

Define recrystallization temperature

A

Attempt at which a heavily cold work (greater than 50% CW) will fully recrystallized in one hour

29
Q

What represents recrystallization temp?

A
30
Q

What is grain growth driven by?

A

Reduction in green boundary area

(Reduction in energy associated with high energy green boundaries)

31
Q

What can green growth be visualized as?

A

Soap, bubbles getting bigger

32
Q

Define the Hall-Petch relationship

A

Drain Greengrove there is a drop in strength with increase in grain size proportional to

1/sqrt(d)

33
Q

At what temperature is hot working done

A

Above a metal’s recrystallization temperature

34
Q

Define hot working

A

Plastic deformation with dynamic recrystallization occurring at the same time as a generation in multiplication of dislocations

35
Q

Hot working: why can’t the dislocation density increase significantly?

A

Due to recrystallization

36
Q

When would a hot working not be used?

A

If good appearance or accurate dimensions are important

37
Q

Hot working: can produce a very large what

A

Reductions in area

38
Q

Is this hot working or cold working and what is the temp?

A
39
Q

Is this hot working or cold working and what is the temp?

A
40
Q

Annealing reduces the total ______ of cold worked metal

A

Energy

41
Q

Annealing: reduces ________ density significantly

A

Dislocation

42
Q

When is kneeling often used?

And why?

A

Between cold working steps to reverse the effects of cold work

So that the final properties can be tailored for a particular dimension of part

43
Q

Does annealing alter the dimensions of a part

A

NO

44
Q

Lower dislocation density means what two things

A

Strength is lower

Ductility is higher

Mat E 202 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions