CWB Welding Inspector Level III
Study Guide
Which of the following metals has the highest thermal conductivity?
(a) carbon steel
(b) stainless steel
(c) aluminum - ✔✔ correct 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. - ✔✔ correct answer (b)
True or False?
A metal with a high negative free energy of oxide formation will generally require greater shielding
from the atmosphere during welding. - ✔✔ correct answer True
Electricity can be conducted by:
(a) atoms and electrons.
(b) electrons and ions.
(c) only ions. - ✔✔ correct 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 - ✔✔ correct answer (b)
Thoria is added to tunsten electrodes for what purpose? - ✔✔ correct answer To increase thermionic
emission by lowering the work function.
True or False?
All pure metals have the same crystal structure. - ✔✔ correct answer False. Metals generally have
one of three basic structures.
, CWB Welding Inspector Level III
Study Guide
Which crystal structure(s) is (are) composed of close-packed planes? - ✔✔ correct answer FCC 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. - ✔✔ correct 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. - ✔✔ correct answer (b)
Which of the following elements are most likely to form interstitial solid solutions?
(a) copper
(b) nickel
(c) carbon - ✔✔ correct answer (c)
If FCC iron has a denser structure than BCC iron, why does it have a higher solubility for carbon? -
✔✔ correct answer The 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? - ✔✔ correct answer One
How many phases are there in a eutectic- one or two? - ✔✔ correct answer Two
Without referring to the text, draw the phase diagram for a eutectic system with limited mutual solid
solubility of the two components. - ✔✔ correct answer Refer to Figure 6.6(Module 20-2014, page
18)
Study Guide
Which of the following metals has the highest thermal conductivity?
(a) carbon steel
(b) stainless steel
(c) aluminum - ✔✔ correct 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. - ✔✔ correct answer (b)
True or False?
A metal with a high negative free energy of oxide formation will generally require greater shielding
from the atmosphere during welding. - ✔✔ correct answer True
Electricity can be conducted by:
(a) atoms and electrons.
(b) electrons and ions.
(c) only ions. - ✔✔ correct 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 - ✔✔ correct answer (b)
Thoria is added to tunsten electrodes for what purpose? - ✔✔ correct answer To increase thermionic
emission by lowering the work function.
True or False?
All pure metals have the same crystal structure. - ✔✔ correct answer False. Metals generally have
one of three basic structures.
, CWB Welding Inspector Level III
Study Guide
Which crystal structure(s) is (are) composed of close-packed planes? - ✔✔ correct answer FCC 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. - ✔✔ correct 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. - ✔✔ correct answer (b)
Which of the following elements are most likely to form interstitial solid solutions?
(a) copper
(b) nickel
(c) carbon - ✔✔ correct answer (c)
If FCC iron has a denser structure than BCC iron, why does it have a higher solubility for carbon? -
✔✔ correct answer The 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? - ✔✔ correct answer One
How many phases are there in a eutectic- one or two? - ✔✔ correct answer Two
Without referring to the text, draw the phase diagram for a eutectic system with limited mutual solid
solubility of the two components. - ✔✔ correct answer Refer to Figure 6.6(Module 20-2014, page
18)
