CWB Welding Inspector Level III Study
Guide Questions & Answers 100%
Correct!!
Which of the following metals has the highest thermal conductivity?
(a) carbon steel
(b) stainless steel
(c) aluminum - ANSWER(c)
The Ellingham diagram
(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. - ANSWER(b)
Thoria is added to tunsten electrodes for what purpose? - ANSWERTo increase
thermionic emission by lowering the work function.
True or False?
All pure metals have the same crystal structure. - ANSWERFalse. Metals generally
have one of three basic structures.
True or False?
A metal with a high negative free energy of oxide formation will generally require
greater shielding from the atmosphere during welding. - ANSWERTrue
Electricity can be conducted by:
(a) atoms and electrons.
(b) electrons and ions.
(c) only ions. - ANSWER(b)
Which of the following elements is often present in submerged arc fluxes to improve
arc stability?
(a) copper
(b) potassium
(c) nickel
(d) tungsten - ANSWER(b)
Which crystal structure(s) is (are) composed of close-packed planes? -
ANSWERFCC and HCP
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. - ANSWER(c)
Multiplication and subsequent congestion of moving dislocations causes:
, (a) elastic extension.
(b) work or strain hardening.
(c) a drop in the yield stress. - ANSWER(b)
Which of the following elements are most likely to form interstitial solid solutions?
(a) copper
(b) nickel
(c) carbon - ANSWER(c)
If FCC iron has a denser structure than BCC iron, why does it have a higher
solubility for carbon? - ANSWERThe preferred site for carbon in BCC iron is smaller
than that in FCC iron.
If two metals have complete mutual solid solubility how many phases are formed in
the solid- one or two? - ANSWEROne
How many phases are there in a eutectic- one or two? - ANSWERTwo
Without referring to the text, draw the phase diagram for a eutectic system with
limited mutual solid solubility of the two components. - ANSWERRefer to Figure
6.6(Module 20-2014, page 18)
Using the portion of the iron-carbon phase diagram in Figure 6.10(Module 20-2014,
page 21), use the lever rule to determine the precentage of ferrite and eutectoid
pearlite present in a slowly cooled 0.2% carbon steel. - ANSWERAbout 25% pearlite
and 75% ferrite. Here the tie line begins at 0.0%C (α 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)/).8%C - 0.0%C) x 100%
% pearlite = (0.2/0.8) x 100%
% pearlite = 25%
How does yield strength vary with grain size? - ANSWERInversely as the square
root of the grain size.
Which of the following factors increases the degree of constitutional supercooling?
(a) very slow solidification rate
(b) an alloy with a very narrow solidification range
(c) an alloy with a wide solidification range - ANSWER(c)
Hot Cracking during welding is more likely in:
(a) pure metals.
(b) alloys with a wide solidification range.
(c) alloys with a very high alloy content. - ANSWER(b)
Which of the following metals has the highest work hardening coefficient?
(a) 70/30 brass
(b) aluminum
(c) copper
(d) low carbon steel - ANSWER(a)
Guide Questions & Answers 100%
Correct!!
Which of the following metals has the highest thermal conductivity?
(a) carbon steel
(b) stainless steel
(c) aluminum - ANSWER(c)
The Ellingham diagram
(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. - ANSWER(b)
Thoria is added to tunsten electrodes for what purpose? - ANSWERTo increase
thermionic emission by lowering the work function.
True or False?
All pure metals have the same crystal structure. - ANSWERFalse. Metals generally
have one of three basic structures.
True or False?
A metal with a high negative free energy of oxide formation will generally require
greater shielding from the atmosphere during welding. - ANSWERTrue
Electricity can be conducted by:
(a) atoms and electrons.
(b) electrons and ions.
(c) only ions. - ANSWER(b)
Which of the following elements is often present in submerged arc fluxes to improve
arc stability?
(a) copper
(b) potassium
(c) nickel
(d) tungsten - ANSWER(b)
Which crystal structure(s) is (are) composed of close-packed planes? -
ANSWERFCC and HCP
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. - ANSWER(c)
Multiplication and subsequent congestion of moving dislocations causes:
, (a) elastic extension.
(b) work or strain hardening.
(c) a drop in the yield stress. - ANSWER(b)
Which of the following elements are most likely to form interstitial solid solutions?
(a) copper
(b) nickel
(c) carbon - ANSWER(c)
If FCC iron has a denser structure than BCC iron, why does it have a higher
solubility for carbon? - ANSWERThe preferred site for carbon in BCC iron is smaller
than that in FCC iron.
If two metals have complete mutual solid solubility how many phases are formed in
the solid- one or two? - ANSWEROne
How many phases are there in a eutectic- one or two? - ANSWERTwo
Without referring to the text, draw the phase diagram for a eutectic system with
limited mutual solid solubility of the two components. - ANSWERRefer to Figure
6.6(Module 20-2014, page 18)
Using the portion of the iron-carbon phase diagram in Figure 6.10(Module 20-2014,
page 21), use the lever rule to determine the precentage of ferrite and eutectoid
pearlite present in a slowly cooled 0.2% carbon steel. - ANSWERAbout 25% pearlite
and 75% ferrite. Here the tie line begins at 0.0%C (α 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)/).8%C - 0.0%C) x 100%
% pearlite = (0.2/0.8) x 100%
% pearlite = 25%
How does yield strength vary with grain size? - ANSWERInversely as the square
root of the grain size.
Which of the following factors increases the degree of constitutional supercooling?
(a) very slow solidification rate
(b) an alloy with a very narrow solidification range
(c) an alloy with a wide solidification range - ANSWER(c)
Hot Cracking during welding is more likely in:
(a) pure metals.
(b) alloys with a wide solidification range.
(c) alloys with a very high alloy content. - ANSWER(b)
Which of the following metals has the highest work hardening coefficient?
(a) 70/30 brass
(b) aluminum
(c) copper
(d) low carbon steel - ANSWER(a)
