CWB WELDING INSPECTOR LEVEL III STUDY
GUIDE QUESTIONS AND 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)
True or False?
A metal with a high negative free energy of oxide formation will generally require greater
shielding from the atmosphere during welding. - ANSWER True
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)
Thoria is added to tunsten electrodes for what purpose? - ANSWER To increase
thermionic emission by lowering the work function.
True or False?
All pure metals have the same crystal structure. - ANSWER False. Metals generally
have one of three basic structures.
, Which crystal structure(s) is (are) composed of close-packed planes? - 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. - 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)
True or False?
Recrystallization always involves the formation of a new phase. - ANSWER False
To get recovery and recrystallization the metal must have been previously
(a) quenched.
(b) heated.
(c) cold worked. - ANSWER (c)
Can strain aging in low carbon steels take place at room temperature? - ANSWER Yes
Why is the temperature range 150°C-400°C usually avoided when forming steels? -
ANSWER Because of "blue brittleness", i.e., lower ductility due to dynamic strain aging.
Which of the following is a condition for an alloy to show precipitation hardening?
(a) there must be a eutectoid system
(b) the solubility of one component must rise with increasing temperature
(c) there must be complete solid solubility - ANSWER (b)
How does yield strength vary with grain size? - ANSWER Inversely 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.
GUIDE QUESTIONS AND 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)
True or False?
A metal with a high negative free energy of oxide formation will generally require greater
shielding from the atmosphere during welding. - ANSWER True
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)
Thoria is added to tunsten electrodes for what purpose? - ANSWER To increase
thermionic emission by lowering the work function.
True or False?
All pure metals have the same crystal structure. - ANSWER False. Metals generally
have one of three basic structures.
, Which crystal structure(s) is (are) composed of close-packed planes? - 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. - 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)
True or False?
Recrystallization always involves the formation of a new phase. - ANSWER False
To get recovery and recrystallization the metal must have been previously
(a) quenched.
(b) heated.
(c) cold worked. - ANSWER (c)
Can strain aging in low carbon steels take place at room temperature? - ANSWER Yes
Why is the temperature range 150°C-400°C usually avoided when forming steels? -
ANSWER Because of "blue brittleness", i.e., lower ductility due to dynamic strain aging.
Which of the following is a condition for an alloy to show precipitation hardening?
(a) there must be a eutectoid system
(b) the solubility of one component must rise with increasing temperature
(c) there must be complete solid solubility - ANSWER (b)
How does yield strength vary with grain size? - ANSWER Inversely 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.
