CWB Welding questions level 3 ABC Exam Questions Reviewed And Revised With Correct Answers <Guarantee Pass |Updated!!>
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Course
CWB Welding Inspector
Institution
CWB Welding Inspector
CWB Welding questions level 3
ABC
Exam Questions Reviewed And
Revised With Correct Answers
<Guarantee Pass |Updated!!>
1) Which of the listed materials has the highest melting point
range?
ANSWER
ceramics
2)The type of crystalline structure found in the centre of a
si...
CWB Level 3 Module > Basic
Metallurgy and Welding Metallurgy
of Aluminum
Exam Questions Reviewed And
Revised With Correct Answers
<Guarantee Pass |Updated!!>
1) What is the cause for weld bead cracking in Al ? - ANSWER
Hot shortness of Al
2) What are the properties of Al ?
- ANSWER 1. low density
2. Corrosion resistance
3. High electrical resistance
4. High thermal conductivity
5. good appearance
6. toughness at low temps
, 3) True / False ?
Al is covered with a coherent oxide. - ANSWER True
4) Thermal conductivity of Al is _______ times that of Steel -
ANSWER 4
5) Melting point of Al is about _______ of Steel - ANSWER
half
6) Coefficient of thermal expansion for Al is about _______ that
of Steel - ANSWER twice
7) Modulus of elasticity (stiffness) for Al is about _______ that
of Steel - ANSWER one-third
8) True / False
"Nitrogen is not inert to Al and is not used for sheilding" -
ANSWER True
9) What is responsible for Al's excellent corrosion resistance? -
ANSWER Al oxide but it changes to Magnesium oxide (MgO)
,or Magnesium spinel ( Mg Al2O4) when the Mg % exceeds
0.05%.
10) What is the thickness of Al oxide on the surface of Al ? -
ANSWER 50-150 angstroms
11) True/ False ?
The form of magnesium oxide is a function of the magnesium
concentration and the thermal history of the alloy - ANSWER
True
13) True / False ?
The oxide transformation from aluminum oxide to magnesium
oxide or magnesium spinel ,has a profound effect on the solid -
state bonding b/w any clad and the Al base - ANSWER True
14) The solid -state bonding b/w Al and another metal or
another Aluminum alloy generally requires a control of the
magnesium level to ____ % - ANSWER Less than 0.05%
, 15) Why does Mg has the profound influence on the oxide
found on Al? - ANSWER 1. Mg has a greater affinity than Al
for O2.
2. Mg behaves as a surface-active element in Al, that is, it tends
to diffuse readily to the surface of the metal.
16) The oxidation rate of Mg containing alloys is
_____________ than for Mg free alloys. - ANSWER greater
17) Why is oxide thickness on an Mg- Al alloy surface thicker
than one on a Mg free alloy for the same thermal / mechanical
history? - ANSWER The oxidation rate of Mg containing
alloys is greater than for Mg free alloys.
18) Which is the element which reacts with Mg oxide to form
its oxides on the Al surface? - ANSWER Lithium
19) Which is the surface oxide for lithium bearing Al alloys? -
ANSWER Lithium oxide / spinel
True / False ?
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