p10-7 task 1

Question 1

which type of electrodes are most commonly used for welding aluminum?

1. striped tungsten
2. 1% thoriated tungsten
3. 2% thoriated tungsten
4. zirconium alloyed tungsten

Answer 1

d. zirconium alloyed tungsten

Question 2

for welding aluminum with the GTAW process, the preferred current is

1. DCEN
2. DCEP
3. ACHF
4. AC

Answer 2

C. ACHF

Question 3

cleaning agents such as trichloroethylene and tetrachlorethylene must not be used to preclean aluminum as the fumes from these substances break down to form deadly

1. propanoic gas
2. phosgene gas
3. piperidine gas
4. paraldehyde gas

Answer 3

b. phosgene gas

Question 4

smaller diameter aluminum filler wires are supplied in the “F” temper which means they are

1. used on tempered aluminum alloys
2. used for welding marine grade aluminum alloys
3. rods that have been softened
4. rods that have been stiffened

Answer 4

d. rods that have been stiffened

Question 5

to weld aluminum using the GTAW process, the electrode is prepared with a

1. sharp point
2. ground end
3. square end
4. balled end

Answer 5

d. balled end

Question 6

hot shortness, a problem common to GTAW on aluminum, is defined as

1. a loss of ductility as the metal reaches its melting temperature
2. a loss of corrosion resistance when the metal is overheated
3. an increase in hardness when the metal is quenched
4. a decrease in impact strength upon cooling

Answer 6

a. a loss of ductility as the metal reaches its melting temperature

Question 7

match the colour code with the correct electrode listed below

1. _____ black
2. _____ orange
3. _____ red
4. _____ green
5. 1100
6. 4043
7. 5254
8. 5056

Answer 7

1. _d____ black
2. _c____ orange
3. _a____ red
4. _b____ green
5. 5056 black
6. 5254 orange
7. 1100 red
8. 4043 green

Question 8

a stainless steel brush used to clean aluminum should

1. have long, angled bristles
2. be cleaned in a caustic soda solution after each use
3. be pre-heated before use
4. be used only for aluminum

Answer 8

d. be used only for aluminum

Question 9

after you pre clean aluminum in a chemical solution you must

1. put the metal through an electrolytic brightening process
2. rinse the metal thoroughly in distilled water
3. brush the metal with an aluminum brush
4. heat treat the metal to restore its temper

Answer 9

b. rinse the metal thoroughly in distilled water

Question 10

after pre-cleaning the aluminum you should weld the joint

1. with a copper backing to prevent recontamination
2. after a 3 hour standing time
3. as soon as you possibly can
4. while it is still moist from rinsing

Answer 10

c. as soon as you possibly can

Question 11

the problems of cracking and holes associated with hot shortness can be averted by

1. reducing your travel speed
2. using DCEN
3. control composition of weld metal
4. increasing the root Gap in the joint design

Answer 11

c. control composition of weld metal