Exam (elaborations)

CURRENTLY TESTING CWB Level 3 Module 24 Basic Metallurgy and Welding Metallurgy of Aluminum EXAM QUESTIONS WITH ACTUAL CORRECT DETAILED ANSWERS

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CWB Level 3 Module 24 Basic Metallurgy And Weldi

CURRENTLY TESTING CWB Level 3 Module 24 Basic Metallurgy and Welding Metallurgy of Aluminum EXAM QUESTIONS WITH ACTUAL CORRECT DETAILED ANSWERS CURRENTLY TESTING CWB Level 3 Module 24 Basic Metallurgy and Welding Metallurgy of Aluminum EXAM QUESTIONS WITH ACTUAL CORRECT DETAILED ANSWERS C...

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module 24 basic meta
currently testing cwb level 3 module 24 basic meta
cwb level 3 module 24 basic meta

Institution CWB Level 3 Module 24 Basic Metallurgy and Weldi
Course CWB Level 3 Module 24 Basic Metallurgy and Weldi

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CURRENTLY TESTING CWB Level 3 Module 24 Basic Metallurgy
and Welding Metallurgy of Aluminum EXAM QUESTIONS WITH
ACTUAL CORRECT DETAILED ANSWERS

What is the cause for weld bead cracking in Al ? - ANSWER-Hot shortness of Al

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

True / False ?

Al is covered with a coherent oxide. - ANSWER-True

Thermal conductivity of Al is _______ times that of Steel - ANSWER-4

Melting point of Al is about _______ of Steel - ANSWER-half

Coefficient of thermal expansion for Al is about _______ that of Steel - ANSWER-twice

Modulus of elasticity (stiffness) for Al is about _______ that of Steel - ANSWER-one-third

,True / False

"Nitrogen is not inert to Al and is not used for sheilding" - ANSWER-True

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%.

What is the thickness of Al oxide on the surface of Al ? - ANSWER-50-150 angstroms

True/ False ?

The form of magnesium oxide is a function of the magnesium concentration and the thermal history of
the alloy - ANSWER-True

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

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%

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.

The oxidation rate of Mg containing alloys is _____________ than for Mg free alloys. - ANSWER-greater

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.

Which is the element which reacts with Mg oxide to form its oxides on the Al surface? - ANSWER-Lithium

, Which is the surface oxide for lithium bearing Al alloys? - ANSWER-Lithium oxide / spinel

True / False ?

When the Al oxide is transformed to lithium oxide or spinal, then the coherency between the oxide and
the metal substrate may change. Instead of the oxide being tenacious it may be a porous scale layer that
does not protect the parent metal or that can readily trap moisture or any other air borne contaminant. -
ANSWER-True

True / False ?

Oxide is scrapped off the metal prior to welding Al-Li alloys to minimize the weld porosity - ANSWER-True

True / False?

After mechanical milling or chemical treatment for oxide removal prior to welding, the surface will
almost instantly re-oxidize in dry air. - ANSWER-True

True / False

Oxide removal prior to welding, the surface will form local electrolytic cells between dry and wet
sections and the wet part will corrode preferentially, forming a stain. - ANSWER-True

True / False

Al loses strength with welding - ANSWER-True

Fluxes that can dissolve the oxides on Al are ............ - ANSWER-Halide compounds ( Fluorine, chlorine,
Bromine etc.)

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Exam (elaborations) ·

Exam (elaborations)

CURRENTLY TESTING CWB Level 3 Module 24 Basic Metallurgy and Welding Metallurgy of Aluminum EXAM QUESTIONS WITH ACTUAL CORRECT DETAILED ANSWERS

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