Metal 259

Exam 1 ­ Fall 2001

Only one answer per question. For some questions, you may feel that more than one answer works; choose only the best answer. There is only one correct answer for each question.

0. Code your SS# on your answer sheet now.

1. Yield strength:

a. the elongation of a mat'l
b. the maximum stress a mat'l can stand without fracture
c. a measure of the elasticity of a mat'l
d. the stress required to initiate plastic flow
e. the stress required to initiate elastic flow

2. A practical reason for deforming an alloy

a. to form a solid solution
b. to soften it
c. to strengthen it
d. to anneal it
e. to destroy dislocations

3. Hardness is usually defined as:

a. the ability of a material to undergo plastic deformation before fracture
b. the amount of energy absorbed by a material as it fractures
c. the resistance of a material to deformation by indentation
d. the capacity of a material to absorb energy when elastically deformed
e. none of the above

4. Ageing is:

a. the quenching of an aluminum alloy
b. the process in which all of a second phase is dissolved in an aluminum alloy, forming a solid
solution
c. the process in which dislocations are slowed in their movement through interaction with precipitate particles
d. the process in which fine particles of a second phase form
e. a process which does not involve diffusion

5. Which of the following is a single phase that can occur in steels:

a. CM
b. eutectoid
c. Al-Cu solid solution
d. pearlite
e. carbon

6. According to the Aluminum Association numbering system for aluminum alloys, 2024 indicates:

a. an Al-C alloy
b. an Al-C alloy with 0.24 % C
c. an Al-C alloy with 2.4 % C
d. an Al-Cu alloy with 2.4 % Cu
e. an Al-Cu alloy

7. A dislocation is:

a. a defect which involves interstitial atoms on a slip plane
b. a grain boundary which can slip
c. responsible for the inability of steels to be plastically deformed
d. a pileup against a grain boundary
e. a wonderful structural defect that is present in essentially all metals and alloys

8. What does the T4 in 2024-T4 mean?

a. an aluminum alloy with 0.4% carbon
b. the alloy has been heated to 492 C and held there for 20 minutes
c. the alloy has been quenched at 492 C and aged at room temp
d. the alloy is iron-based with 0.4% carbon
e. all dislocations must be removed by a room temperature heat treatment

9. All steels used in the temperature range from 0° to 100° C must contain:

a. Fe and C
b. Fe and 6.67 w/o C
c. FE
d. MAR
e. AUS

10. Dislocations:

a. move along a slip plane
b. move in a direction perpendicular to a slip plane
c. cannot be destroyed
d. move in response to a tensile force in the direction of the slip plane
e. can move in any direction in a slip plane

11. Which of the following does not involve diffusion:

a. cold working
b. austenitization
c. ageing
d. annealing
e. none of the above

12. A 1020 steel, slowly cooled to room temperature, contains:

a. roughly equal amounts of FE and P
b. 0.20% C
c. all AUS
d. all MAR
e. all Pearlite

13. Aluminum alloys cannot be strengthened by:

a. cold working
b. precipitation hardening
c. solution hardening
d. quenching

14. Steels cannot be strengthened by

a. quenching
b. adding more carbon
c. adding alloying elements
d. annealing
e. cold working

15. Which is false?

a. no dislocations = extremely strong material
b. no dislocations = extremely ductile material
c. many dislocations = strong material
d. the presence of dislocations weakens a material

16. Impede dislocation motion:

a. precipitate particles
b. other dislocations
c. grain boundaries
d. solute atoms
e. all of the above

17. An aluminum-4% copper alloy is heated to 500° C and quenched. Upon quenching:

a. the temperature increases
b. precipitate particles form
c. a solid solution is formed
d. the alloy is strengthened
e. nothing (other than the mat'l cools and probably shrinks)

18. Rank 1-2-3-4 for possible strength (1 = highest)

Steels Al alloys polymers ceramic mat'ls

a. 3 2 1 4

b. 1 2 4 3

c. 2 3 4 1

d. 3 2 4 1

e. 1 3 2 4

19. Choose the correct dependence for hardness:

(figure missing)

20. A slip system consists of:

a. a slip plane and a shear stress
b. a slip plane and an edge dislocation
c. a slip plane and a slip direction
d. an edge dislocation and a shear stress
e. an edge dislocation and a slip direction

21. The higher the percent carbon in a steel,

a. the higher the brittle to ductile transition temperature
b. the lower the brittle to ductile transition temperature
c. the amount of carbon present does not effect the transition temperature
d. more dislocations form upon heating
e. fewer dislocations form upon heating

22. Which of the following is not a method for strengthening metals and alloys:

a. cold working
b. precipitation hardening
c. solution hardening
d. work hardening
e. none of the above

23. The ease of dislocation motion depends upon:

a. the presence of alloy elements in a material
b. the presence of precipitates in an alloy
c. the number of available slip systems
d. all of the above

24. A heat treated Al alloy contains, at room temperature, an Al-Mg-Fe-Si solid solution, an Mg-Si precipitate, and an Al-Fe-Si precipitate. How many states and phases?

a. 1 state, 1 phase
b. 3 states, 1 phase
c. 1 state, 4 phases
d. 1 state, 3 phases
e. 3 states, 4 phases

25. Another name for precipitation hardening:

a. solution hardening
b. age hardening
c. work hardening
d. austenitization
e. annealing