120103i Flashcards
Up to what length of contact tip is best suited for GMAW with aluminum filler wires?
a) 25.4mm / 1”
b) 50.8 mm / 2”
c) 76.2 mm / 3”
d) 101.6 mm /4”
d) 101.6 mm /4”
List 3 advantages of using GMAW on Al
Any of the following 3 are correct
- High deposition rates compared to GTAW
- can be used long distances from the power source
- no flux or slag; no inclusions in the weld
- clean up time is reduced or eliminated
- may be used in all positions
- works well on materials 3.2mm (1/8”)
works well for spot welding operations
Which Al filler metal is not recommended for sustained high temp service
a) 2319
b) 4145
c) 4043
d) 5356
d) 5356
because of its high Mg content it is prone to stress corosion cracking
What 3 factors should you consider when setting GMAW welding parameters?
Material thickness
alloy type
available equipment
What effect does stick out have on arc length with GMAW on Al
Very little change in arc length is noticed with various stick out distances.
This is due to the high electrical conductivity of Al, the ESO is not as critical as that required for steel
After pre-cleaning Al, you should weld the joint:
a) with copper backing bar to prevent oxide contamination
b) before it dries to prevent cracking
c) after age hardening has occurred
d) as soon as all liquids have evaporated from the area
d) as soon as all liquids have evaporated from the area
What precaution must you take when using heavy wire brushing or an abrasive grinding disk to remove a heavy oxide layer from Al
Heavy brushing or abrasive disks tend to drive Al oxides into the surface and entrap them.
The result is possible contamination of the weld
What are the 2 most commonly used filler metals for GMAW on Al
a) 2319 & 4145
b) 4145 & 5356
c) 4043 & 4047
d) 4043 & 5356
d) 4043 & 5356
What is the purpose of a light preheat on Al alloys
a) to remove moisture
b) to reduce residual stresses after welding
c) easier arc starting
d) to remove surface oxides
a) to remove moisture
What type of current do you use with GMAW for welding Al
a) AC
b) DCEP
c) DCEN
d) AC with continuous high frequency
b) DCEP
What methods can you use to fill a crater?
-reverse travel direction for a short distance
- use run-off tabs
- breaking and restarting the arc
- the use of special current controls on the power source
What electrode inclination is recommended for welding Al?
a) forehand
b) backhand
c) forehand at all times
d) backhand at all times
c) forehand at all times
Most shielding gasses for GMAW on Al are:
a) inert gases
b) oxidizing gases
c) nitriding gases
d) ionized gases
a) inert gases
The shielding gas most commonly used with GMAW on non-ferrous metals is
a) carbon dioxide
b) nitrogen
c) helium
d) argon
d) argon
List 4 causes of burn back
Any of the following 4 are correct:
wire feed to slow
worn or dirty tip, or liner
wrong polarity
kinked electrode wire
liner to long
arcing inside the contact tube
What happens when you use a backhand inclination when using GMAW on Al?
a) lack of fusion
b) the wire tends to burn back into the contact tube
c) a black soot oxide appears on the surface
d) excessive bead convexity
c) a black soot oxide appears on the surface
Preheat applied to Al components is:
a) done using inductance heating methods only
b) seldom required to exceed 149°C (300°F)
c) not applied unless the ambient temp is below -18°C (0°F)
d) done only prior to solution heat treating
b) seldom required to exceed 149°C (300°F)
The recommended technique and metal transfer for GMAW on Al is:
a) pulsed spray transfer with a long stickout
b) forehand (pushing) inclination with short circuit or spray transfer
c) backhand ( pulling) inclination with spray transfer
d) fast travel speed with continuous high frequency current transfer
b) forehand (pushing) inclination with short circuit or spray transfer
What element causes porosity in an Al weld
a) O2
b) N2
c) CO2
d) hydrogen
d) hydrogen
What can happen if you leave a crater at the end of an Al weld?
a) porosity
b) oxidization
c) cracking
d) lack of fusion
c) cracking
T / F
By using GMAW mode of metal transfer, Al can be welded using both manual and semi-automatic welding methods
True
Are each of the following statements T / F?
1. You can achieve high deposition rates on Al with GMAW compared to GTAW _________
2. Welding long distances from the power source is possible using a push-pull gun __________
3. Flux and slag are common inclusions ________
4. You can weld in all positions __________
5. The GMAW process is not adaptable on thin materials ______
- T
- T
- F - there is no flux or slag to become entrapped
- T
- F - GMAW is readily adaptable on materials as thin as 1/8”
Using GMAW on Al which technique is preferred?
Stringer beads or weave bead technique
Stringer beads
What type of liner must you use?
nylon or teflon liners
- they help min the drag on the wire
Is a longer or shorter contact tip preferred when welding Al with GMAW?
The longer the better as it is easier to feed the wire as the current transfer is more efficient. some are 4” long
What are the 2 most common shielding gasses when welding Al?
a) Helium & CO2
b) Helium & Argon
c) Argon & O2
d) Argon & CO2
b) Helium & Argon
Helium
- greater penetration, broader root with less cleaning & poor arc initiation.
- higher flow rates & therefore higher $
Argon
- more effective, good cleaning action, stable & easy to start arc
- lower $
- usually preferred for the non ferrous metals
- used extensively on semi-automatic processes
What is necessary for oxide removal?
a) heavily abrasive wire brushes, power brush, stainless wire wool
b) alkaline solution and tools such as SS wire brush, SS power brush, SS wire wool with light pressure
c) alkaline solution and tools such as heavily abrasive wire brushes, power brush, stainless wire wool
d) once Al has oxidized there is no way to clean it off
b) alkaline solution and tools such as SS wire brush, SS power brush, SS wire wool with light pressure
What are the 2 most common filler metals when welding Al?
a) 4043 & 5355
b) 4043 & 5356
c) 4053 & 5356
d) 4053 & 5535
b) 4043 & 5356
Which filler wire is suitable for high temp service?
a) 5535
b) 4043
c) 5554
d) 5535
c) 5554
it has a low Mg content and is not prone to stress cracking
How would you remove traces of moisture before welding Al?
a) heavy preheat
b) light preheat
c) allow to air dry
d) use chemicals which evaporate quickly to dry the surface
b) light preheat
What current type is used for welding Al with GMAW
a) DCEP
b) DCEN
c) AC
d) current type depends on the thickness of the plate
a) DCEP
Alloy groups require different ESO and have different sounds with each, describe the sound each type would have
1. 5XXX - low voltage - high amperage - aprox 1/4” ESO
2. 4XXX - High voltage - low amperage - aprox 3/8” - 1/2” ESO
- 5XXX has a crackling sound
- 4XXX has a hum
When welding using the 5000 series electrodes which statement is correct?
a) use lower currents and higher voltages
b) use high currents and low voltages
c) both use lower currents and higher voltages
d) both use higher currents and higher voltages
b) use high currents and low voltages
When welding using the 1000, 2000, 4000 series electrodes which statement is correct?
a) use lower currents and higher voltages
b) use high currents and low voltages
c) both use lower currents and higher voltages
d) both use higher currents and higher voltages
a) use lower currents and higher voltages
Does Al have high or low electrical conductivity?
High electrical conductivity
With Al having much higher travel speeds what change to your equipment would you need to make?
a) change current type
b) use heavy preheat
c) use a larger nozzle
d) no changes are needed due to travel speed
c) use a larger nozzle
What room temperature or preheat is generally adequate
a) up to 149°C (300°F)
b) 0°C 32°F
c) 66°C 150°F
d) Al doesn’t require preheat
c) 66°C 150-°F
When welding Al why is it necessary to remove all water?
As H2O breaks down during welding the hydrogen enters the Al and causes porosity
What electrode angle is used with GMAW on Al.
a) 1/4 the included angle
b) 1/2 the included angle
c) 3/4 the included angle
d) electrode angle is not as important as it is with steels
b) 1/2 the included angle
What inclination is used with Al welding
a) 10-20° back hand
b) 10-20° forehand
c) 0-30° back hand
d) 0-30° forehand
d) 0-30° forehand
T / F
If using 0°-30° forehand the resulting weld bead is clean with good appearance
True
Are the following true or false?
The use of a back hand technique
_____ deeper penetration
_____ soot oxide appears on the surface
Both are true
How do you fill a crater to prevent cracking?
a) reverse direction for a short distance
b) use run off tabs
c) breaking and restarting the arc
d) using special current controls on the power source
e) all of the above
e) all of the above
What electrodes are these welding parameters for
a) ER4043
b) ER5356
c) ER 5653
d) both 4043 & 5356
d) both 4043 & 5356
For a 1F weld on Al using Short circuit or spray transfer what should your eso be?
a) as short as possible
b) as long as possible and still maintain the arc
c) 3/8”
d) 1/4”
a) as short as possible to supply adequate shielding gas coverage