Ch 7

Question 1

Define annealing

(Two things)

Answer 1

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

Question 2

Annealing can reverse the effects of what

Answer 2

Strain hardening

Question 3

Three things annealing does

Answer 3

Question 4

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

Answer 4

Thermally activated process

Involves atomic rearrangement, especially with atoms, located in dislocations

Question 5

List the three stages of annealing in order

Answer 5

Recovery

Recrystallization

Grain growth

Question 6

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

Answer 6

Recovery: minor changes in properties

Recrystallization: significant changes in properties

Grain growth: minor changes in properties

Question 7

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

Answer 7

Recovery: smallest

Recrystallization: larger

Grain growth: largest

Question 8

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

Answer 8

Green growth and recrystallization

Recovery always happens

Question 9

What are the three vertical sections on this diagram?

Answer 9

Question 10

Describe what happens to the grains during annealing

Answer 10

Question 11

Define recovery

Answer 11

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

Question 12

In a light microscope is recovery visible

Answer 12

No

Question 13

Define stress relief anneal

Answer 13

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

Question 14

Does a stress relief anneal result in significant property changes

Answer 14

No

Question 15

What phase of annealing does a stress relief anneal occur

Answer 15

Recovery

Question 16

What happens during recovery?

Answer 16

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

Question 17

What does equiaxed grain structure mean?

Answer 17

Grains with nearly equal dimensions

Question 18

Define nucleation

Answer 18

The initial stage in phase transformation

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

Question 19

Define recrystallization

Answer 19

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

Question 20

What does recrystallization reverse?

Answer 20

The effects of cold, working, or strain hardening

Question 21

During recrystallization what decreases in what increases

Answer 21

Strength decreases

Ductility increases

Question 22

When does the recovery stage occur?

(in terms of temp)

Answer 22

Occurs at lowest temp her first at higher temps

(since it has the lowest activation energy

Question 23

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

Answer 23

Strength is retained

Internal stresses are removed

Question 24

Is there any recrystallization during a stress relief anneal?

Answer 24

NO

Question 25

Recrystallization: will not occur unless what

Answer 25

A certain amount of %CW has been done (About 2-20%, about 5% for iron)

Question 26

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

Answer 26

You get sigmoidal (S shaped curves)

Question 27

Recrystallization: what does a higher temperature mean?

Answer 27

Faster reaction Small drop in temperature means large increase in time

Question 28

Define recrystallization temperature

Answer 28

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

Question 29

What represents recrystallization temp?

Answer 29

Question 30

What is grain growth driven by?

Answer 30

Reduction in green boundary area (Reduction in energy associated with high energy green boundaries)

Question 31

What can green growth be visualized as?

Answer 31

Soap, bubbles getting bigger

Question 32

Define the Hall-Petch relationship

Answer 32

Drain Greengrove there is a drop in strength with increase in grain size proportional to 1/sqrt(d)

Question 33

At what temperature is hot working done

Answer 33

Above a metal’s recrystallization temperature

Question 34

Define hot working

Answer 34

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

Question 35

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

Answer 35

Due to recrystallization

Question 36

When would a hot working not be used?

Answer 36

If good appearance or accurate dimensions are important

Question 37

Hot working: can produce a very large what

Answer 37

Reductions in area

Question 38

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

Answer 38

Question 39

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

Answer 39

Question 40

Annealing reduces the total ______ of cold worked metal

Answer 40

Energy

Question 41

Annealing: reduces ________ density significantly

Answer 41

Dislocation

Question 42

When is kneeling often used? And why?

Answer 42

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

Question 43

Does annealing alter the dimensions of a part

Answer 43

NO

Question 44

Lower dislocation density means what two things

Answer 44

Strength is lower Ductility is higher