Test 2. Chapter 7

Question 1

Plastic deformation by ______ or ________where one plane of atoms slides over adjacent plane by defect motions (dislocation)

Answer 1

plastic shear or slip

Question 2

if dislocations dont move, deformation ______ occur

Answer 2

doesnt

Question 3

dislocation move along ______ in ______ perpendicular to dislocation line

Answer 3

slip plane

slip direction

Question 4

slip direction same as _________

Answer 4

burgers vector

Question 5

*** Slip relys on what two parts? And describe

Answer 5

slip plane-plane allowing easiest slippage. It has wide interplanar spacings- HIGHEST PLANAR DENSITIES

slip direction-direction of movement- It has HIGHEST LINEAR DENSITIES

Question 6

crystals slip due to a ___________

applied tension can produce such stress

Answer 6

resolved shear stress

Question 7

for dislocation motion resolved shear stress TR must be greater than what?

Answer 7

TCRSS

so for deformation to occur the applied stress must be greater than or equal to the yield stress

Question 8

isotropic=

anisotropic=

Answer 8

since grains are approx. spherical and randomly orientated

since rolling affects grain orientation and shape

Question 9

What are the strategies for strengthening?

Answer 9

1. reduce grain size
2. solid solutions
3. Precipitation Strengthening
4. Cold Work

Question 10

_____________ are barriers to slip. Barrier “strength” increasing with increasing angle of misorientation. Smaller grain size: more barriers to slip

Answer 10

grain boundaries

Question 11

Impurity atoms distort the lattice and generate stress. _______ can produce a barrier to dislocation motion

Answer 11

stress

Question 12

dislocations entangle with one another during _________. Dislocation motion becomes more difficult

Answer 12

cold work

Question 13

As cold work is increased. How does yield stress, tensile strength, and ductility change? (increase or decrease)

Answer 13

yield strength increase

tensile strength increase

ductility decrease

Question 14

Anealing and _________ affects of cold work

Answer 14

reverse

it is a heating process

Question 15

annihilation reduced ___________ density

Answer 15

dislocation

Question 16

during annilhation, new grains are formed that have:

Answer 16

• have a small disloaction density
• are small
• consume cold-worked grains

Question 17

At longer times, larger grains consume smaller ones. Why?

Answer 17

It is because of the grain boundary area (and therefore energy can be reduced)

Question 18

dislocations are observed primarily in __________ and __________

Answer 18

metals and alloys

Question 19

strength is increased by making dislocation motion ___________

Answer 19

difficult

Question 20

what are the particular ways to increase strength?

Answer 20

• decrease grain size
• solid solution strengthening
• precipitate strengthening
• cold work

Question 21

heating (____________________) can reduce dislocation density and increase grain size. This decrease the strength

Answer 21

annealling