rk7-3 task 2

Question 1

What effect does copper as an alloying element have on aluminum alloys?

1. increase tensile strength
2. raises melting temperature
3. reduces thermal conductivity
4. counteracts hot shortness

Answer 1

d. counteracts hot shortness

Question 2

which of the following is the strongest aluminum alloy?

1. aluminum-silicon
2. aluminum-magnesium-silicide
3. aluminum-zinc-manganese
4. aluminum-copper

Answer 2

c. aluminum-zinc-manganese

Question 3

which alloy is characterized by high fluidity?

1. aluminum-silicon
2. aluminum-zinc-manganese
3. aluminum–copper
4. aluminum-magnesium

Answer 3

a. aluminum-silicon

Question 4

which alloy has a particularly good anti-friction characteristics?

1. aluminum-magnesium
2. aluminum-silicon
3. aluminum-tin
4. aluminum-manganese

Answer 4

c. aluminum-tin

Question 5

before welding wrought aluminum you need to

1. demagnetize the metal
2. apply an anodizing treatment
3. remove the oxide film
4. put the metal through an annealing process

Answer 5

c. remove the oxide film

Question 6

aluminum has high thermal conductivity. For this reason when welding aluminum you need to

1. use a higher rate of heat input
2. decrease your current setting
3. heat treat the metal after welding
4. apply flux to the joint area before welding

Answer 6

a. use a higher rate of heat input

Question 7

define hot shprtness.

1. a tendency of the weld area to harden
2. complete loss of ductility when the metal nears its melting point
3. tendency of the root bead to sink
4. change in space lattice structure upon Heating

Answer 7

b. complete loss of ductility when the metal nears its melting point
* loss of _ductility _ plasticity causes weld cracking unless the composition and stresses are controlled.**

Question 8

which alloys are especially prone to hot shortness?

1. 3003
2. 5056
3. 5454
4. 6061

Answer 8

d. 6061
* others easily prone to hot shortness include*
* 6063, 6160, 6351, 5052 and 7004*

Question 9

which of the following conditions in castings decreases their weldability?

1. shrinkage
2. undercut
3. hot shortness
4. deoxidization

Answer 9

a. shrinkage

Question 10

which of the following alloys is not prone to hot shortness?

1. 5052
2. 5154
3. 6063
4. 6101

Answer 10

b. 5154
* others also not prone to hot shortness include*
* 1050, 1100, 3003, 5454, 5083 and 5056*