CWB Level 3 Module 20 Practice questions With Answers
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Course
CWB
Institution
CWB
CWB Level 3 Module 20 Practice questions With Answers
1. Which of the following metals has the highest thermal conductivity? C
(a) carbon steel
(b) stainless steel (
(c) aluminum: (c) aluminum
2. The Ellingham diagram C
(a) is a plot of thermal conductivity against temperature.
(b) shows the...
CWB Level 3 Module 20 Practice questions
Study online at https://quizlet.com/_c5vppb
1. Which of the following metals has the highest thermal conductivity? C
(a) carbon steel
(b) stainless steel (
(c) aluminum: (c) aluminum
2. The Ellingham diagram C
(a) is a plot of thermal conductivity against temperature.
(b) shows the free energy of oxide formation against temperature.
(c) shows the rate of oxidation of metals against temperature.: (b) shows the
free energy of oxide formation against temperature.
3. True or False?
A metal with a high negative free energy of oxide formation will generally
require
greater shielding from the atmosphere during welding.: True
4. Electricity can be conducted by:
(a) atoms and electrons.
(b) electrons and ions. C
(c) only ions.: (b) electrons and ions. C
5. Which of the following elements is often present in submerged arc fluxes
to improve arc
stability?
(a) copper (
(b) potassium (
(c) nickel C
(d) tungsten: (b) potassium (
6. Thoria is added to tungsten electrodes for what purpose?: To increase
thermionic emission by lowering the work function.
7. True or False?
All pure metals have the same crystal structure.: False. Metals generally have
one of three basic structures.
8. Which crystal structure(s) is (are) composed of close-packed planes?: FCC
and HCP
9. The real strength of metals is lower than the theoretical value because:
(a) real crystals always fracture along specific crystal planes.
(b) grain boundary sliding occurs.
(c) the presence of dislocations facilitates slip.: (c) the presence of dislocations
facilitates slip.
10. Multiplication and subsequent congestion of moving dislocations causes:
(a) elastic extension.
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, CWB Level 3 Module 20 Practice questions
Study online at https://quizlet.com/_c5vppb
(b) work or strain hardening.
(c) a drop in the yield stress.: (b) work or strain hardening.
11. Which of the following elements are most likely to form interstitial solid
solutions?
(a) copper
(b) nickel
(c) carbon: (c) carbon
12. If FCC iron has a denser structure than BCC iron, why does it have a higher
solubility
for carbon?: The preferred site for carbon in BCC iron is smaller than that in FCC
iron.
13. If two metals have complete mutual solid solubility how many phases are
formed in the
solid— one ortwo?: One
14. How many phases are there in a eutectic—one or two?: Two
15. Without referring to the text, draw the phase diagram for a eutectic system
with limited
mutual solid solubility of the two components.: Refer to Figure 6.6.
16. Using the portion of the iron—carbon phase diagram in Figure 6.10, use
the lever rule to
determine the percentage of ferrite and eutectoid pea rlite present in a slowly
cooled
0.2% carbon steel.: About 25% pearlite and 75% ferrite. Here the tie line begins at
0.0%C (a ferrite) and
ends at 0.08%C (pearlite).
The fulcrum for the lever rule is at 0.2%C
% pearlite = (0.2%C — 0.0%C)I(0.8%C — 0.0%C) x 100%
% pearlite = (0.2/0.8) x 100%
% pearlite = 25%
17. Which of the following metals has the highest work hardening coefficient?
(a) 70/30 brass
(b) aluminum
(c) copper
(d) low carbon steel: a
18. True or False?
Recrystallization always involves the formation of a new phase.: False
19. To get recovery and recrystallization the metal must have been previously
(a) quenched.
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