CWB Level 3 Module 24 Basic Metallurgy
and Welding Metallurgy of Aluminum
At critical stress levels, Al alloys will be prone to ... - ANSHot short cracking .. Occurs when
Al alloys are partially solidified
What temperature melts Al? - ANS660 C What temperature melts Al oxides? - ANS2072 C
Chlorine gas from a Chloride flux in presence of an arc can create poisonous gas called
.......... - ANSPhosgene (COCL2) or Mustard gas produced by the reaction of chlorine and
carbon monoxide in the presence of intense light
Coefficient of thermal expansion for Al is about _______ that of Steel - ANStwice
Al's coefficient of thermal expansion is about twice that of steel, which means that Al's
dimensional change will be twice as great as steel's for the same temperature rise. Distortion
is higher than steel. Additionally, distortion is more obvious on the brightly reflective surface
of bare aluminum than it is on steel. What is die casting of Al alloys? - ANS> the process of
forcing molten Al alloy into a steel mold under pressure > produces a net-like shape >
process that can handle Al alloys of lower purity and is cost-effective for large-scale
production. > recycled (secondary) Al can be the feed stock
Describe permanent casting - ANS> moulds and cores are made of steel
> Al was pumped into the mold by gravity, pressure, or vacuum. > moulds represent
substantial investment and therefore relatively high volume production is required
ANS> Describe sand casting: any pattern can be used to press sand into a mold. > sand
extracts heat more slowly than metal moulds
> Compared to the other two processes, productivity is lower. > used for low production runs
Distortion is an issue bcs it can :- - ANS1. Have a negative impact on how the part is fitted
for the final assembly. 2. Cause the welded component to have an unacceptable
appearance
3. cause the finished product to have an unattractive physical appearance. 4. Cause the
joint line to move.
Does age strengthening of AA-7004 & AA-7005 require rapid cooling/water quenching to
retain constituents in the solid solution? - ANSNo
Ductility of Al casting is very low in ................... castings - ANSSand
Al oxides can be dissolved by the following fluxes: ANSHalide compounds (fluorine,
chlorine, bromine, and so on). For the same heat input, AA-5083 will have a .................
penetration weld than 6061 T6 - ANSdeeper
How do filler alloys prevent cracking? - Utilize the GMAW and GTAW processes. By
increasing the magnesium content of the weld pool, filler alloys like AA 5356 have the
potential to shift the weld bead composition of an AA-5052 joint to a less crack-sensitive
region. How are strengthening mechanisms divide Wrought Al Alloys? - ANS1. Non-heat
treatable / work hardening alloys ( 1XXX, 3XXX, 4XXX and 5XXX alloy series)
2. Heat treatable alloys (2XXX, 6XXX, 7XXX)
How does the 2nd digit applies to the non-heat treatable alloys ? - ANS> 0-8
> denotes the degree of work hardening.
and Welding Metallurgy of Aluminum
At critical stress levels, Al alloys will be prone to ... - ANSHot short cracking .. Occurs when
Al alloys are partially solidified
What temperature melts Al? - ANS660 C What temperature melts Al oxides? - ANS2072 C
Chlorine gas from a Chloride flux in presence of an arc can create poisonous gas called
.......... - ANSPhosgene (COCL2) or Mustard gas produced by the reaction of chlorine and
carbon monoxide in the presence of intense light
Coefficient of thermal expansion for Al is about _______ that of Steel - ANStwice
Al's coefficient of thermal expansion is about twice that of steel, which means that Al's
dimensional change will be twice as great as steel's for the same temperature rise. Distortion
is higher than steel. Additionally, distortion is more obvious on the brightly reflective surface
of bare aluminum than it is on steel. What is die casting of Al alloys? - ANS> the process of
forcing molten Al alloy into a steel mold under pressure > produces a net-like shape >
process that can handle Al alloys of lower purity and is cost-effective for large-scale
production. > recycled (secondary) Al can be the feed stock
Describe permanent casting - ANS> moulds and cores are made of steel
> Al was pumped into the mold by gravity, pressure, or vacuum. > moulds represent
substantial investment and therefore relatively high volume production is required
ANS> Describe sand casting: any pattern can be used to press sand into a mold. > sand
extracts heat more slowly than metal moulds
> Compared to the other two processes, productivity is lower. > used for low production runs
Distortion is an issue bcs it can :- - ANS1. Have a negative impact on how the part is fitted
for the final assembly. 2. Cause the welded component to have an unacceptable
appearance
3. cause the finished product to have an unattractive physical appearance. 4. Cause the
joint line to move.
Does age strengthening of AA-7004 & AA-7005 require rapid cooling/water quenching to
retain constituents in the solid solution? - ANSNo
Ductility of Al casting is very low in ................... castings - ANSSand
Al oxides can be dissolved by the following fluxes: ANSHalide compounds (fluorine,
chlorine, bromine, and so on). For the same heat input, AA-5083 will have a .................
penetration weld than 6061 T6 - ANSdeeper
How do filler alloys prevent cracking? - Utilize the GMAW and GTAW processes. By
increasing the magnesium content of the weld pool, filler alloys like AA 5356 have the
potential to shift the weld bead composition of an AA-5052 joint to a less crack-sensitive
region. How are strengthening mechanisms divide Wrought Al Alloys? - ANS1. Non-heat
treatable / work hardening alloys ( 1XXX, 3XXX, 4XXX and 5XXX alloy series)
2. Heat treatable alloys (2XXX, 6XXX, 7XXX)
How does the 2nd digit applies to the non-heat treatable alloys ? - ANS> 0-8
> denotes the degree of work hardening.
