Final Test Flashcards
True/False: The gas tungsten arc welding process can be used to join nearly all types and thicknesses of metal.
True
True/False: One drawback of GTA welding is that welders have an obstructed view of the molten weld pool.
False
True/False: Charts and graphs that give the correct amperage, gas flow rate, and time for various welds and metals were designed for optimum conditions in the field.
False
True/False: If the end of the filler rod becomes oxidized it must be cut before restarting.
True
True/False: The indicated power to a weld from two different types of welding machines set at 100 amperes will vary depending upon the voltage of the machine.
True
True/False: The amperage set on a machine and the actual welding current are often not the same.
True
True/False: Mild steel is expensive and requires the most amount of cleaning.
False
True/False: When welding mild steel, slight changes in the metal have a large effect on the welding skill required.
False
True/False: Black crusty spots appearing on weld beads are often caused by improper cleaning of the filler rod.
True
True/False: The molten aluminum weld pool has low surface tension.
False
Which of the following is a reason to use GTA welding?
When a close-tolerance, high-quality weld is required.
In GTA welding, the torch may be angled ____ for better visibility.
0 to 15 degrees from perpendicular
If the end of the filler rod is removed from the shielding gas protection protection, _____.
It will oxidize rapidly.
A _____ degree angle or less to the plate surface prevents air from being pulled into the welding zone behind the rod.
15
Which of the following is true of tungsten contamination?
Tungsten contamination causes a weak weld and must be cleaned.
Which of the following is true of welding machine settings?
The setting will differ for various sizes and types of tungsten from machine to machine.
When a weld is contaminated by the tungsten touching the molten weld pool, ____ before resuming welding.
Both the weld and the tungsten must be cleaned.
The gas preflow and postflow times depend on which of the following?
Nozzle size
The ____ possible gas flow rates and the ____ preflow or postflow time can help reduce the cost of welding.
Lowest, shortest.
Exceeding the maximum gas flow rates ____.
Causes weld contamination.
With ____, surface tension helps hold the metal in place, giving excellent bead contour.
Aluminum
With ___, cleanliness is a critical factor.
Aluminum
____ is inexpensive and requires the least amount of cleaning.
Mild steel
With ____, lack of cleanliness may cause the weld pool to show overheating and poor gas coverage.
Stainless Steel
Oxides on _____ may prevent the molten weld weld pool from flowing together.
Aluminum
Carbide precipitation is the combining of _____.
Carbon with chromium
The greater the contamination of a stainless steel weld, ____ of the bead after the weld.
The darker the color.
In the GTAW process, contamination left on the metal will be deposited in the weld because ____.
There is no flux to remove it.
The most common types of contaminants are _____.
Oxides, oils, and dirt.
The torch may be angled for better visibility, and still have the proper shielding _____.
Gas coverage.
As the gas flows out of the torch it must form a ______ around the weld.
Protective Zone
When tungsten touches the molten weld pool, _________ pulls the contamination up onto the hot tungsten.
Surface Tension
Failure to remove tungsten contamination properly will result in ________.
Weld failure
During the manufacturing process, sometimes pockets of primarily ________ has become trapped inside low carbon and mild steels.
Carbon Dioxide
With stainless steel, it is desirable to take the time and necessary precautions to make welds that are no darker than the color _______.
Dark Blue
Most GTA filler metals have some alloys, called _________, that can help prevent porosity caused by gases trapped in the base metal.
Deoxidizers
________ is GTA welded using an EWP, EWZr, EWCe-2, or EWLa-1 rounded tip tungsten, with the welding machine set for ACHF welding current.
Aluminum
A thick piece of metal that is used to absorb heat is also called an _____.
Chill plate.
Mild steel weld coupons can have the welds removed using an OFC torch, but welds on stainless and aluminum coupons will have to be cut out with a _____ torch.
Plasma torch.
Describe how the velocity of the shielding gas and the torch angle affects the protective zone.
The torch angle affects the protective zone because if you move too much your weld will be unprotected from the atmosphere.
Explain why the filler rod end must be kept inside the protective zone.
The filler rod must be kept in the protective zone for it oxides quickly and can contaminate the weld.
Explain why a few molecules of gas trapped inside microscopic pockets within the steel can cause porosity in GTA welding, but not in other types of welding.
There is no flux to remove it.
True/False: In semiautomatic or automatic processes, the welder is required to work harder because of the greater demands on travel speed and current.
False
True/False: The same equipment may be used for may be used for semiautomatic GMAW, FCAW, and SAW.
True
True/False: Wire should not be discarded on the floor because it can work its way into a filter screen on the welding power source.
True
True/False: The lower the density of a gas, the lower the flow rate required for equal arc protection.
False
True/False: More amperage is required to melt the wire the faster it is fed.
True.
True/False: Slight changes in the welding gun angle can be used to control the weld as the groove spacing changes.
True
True/False: The amount of reactive gas required to produce the desired effects is quite small.
True
True/False: Hot-rolled steel has a thin copper layer in which is formed during the rolling process.
False
True/False: Vertical down welds should never be used on thin sheet metals.
False
True/False: The heat produced during GMA welding is sufficient to force 100% penetration consistently, making it ideal for industrial applications.
False
The equipment for _____ is more likely to be automated.
FCAW and SAW
While less likely to be automated, _____ welding equipment can be automated easily.
GMA
Electrode wire has a natural curve that is known as its ______.
Cast
The _______ the density of a gas, the _______ will be the flow rate required for equal arc protection.
Lower, higher.
The correct flow rate of a shielding gas can be set by ____.
Checking welding guides.
High gas flow rates _____.
Waste shielding gas.
Which of the following gases is the least dense?
Helium
In GMA welding, the voltage is set ____ and the amperage is set _____.
On the welder, by changing the wire-feed speed.
At any one voltage setting, ____ amperage is required to melt the wire the _____ it is fed.
More, faster.
The longer the ____, the greater the _____ to the welding current.
Electrode extension, resistance.
As the electrode extension is shortened, the welding current ___.
Decreases
_____ is increased and ____ is decreased as the electrode extension is shortened.
Penetration, buildup.
Slight changes in _____ can be used to control the weld as the groove spacing changes.
Welding gun angle.
A _____ gap may require _____.
Wide, more penetration.
____ provide the necessary shielding because they do not form compounds with any other substance.
Inert gases
Which of the following is true of mill scale?
The porosity it causes is most often confined to the interior of the weld.
Which of the following deoxidizinf elements is weak?
Manganese
A weld that is high and his little or no fusion is too “cold.” To correct this, ____.
Stop welding and make the needed adjustments.
The major advantages of the vertical down position technique are _____.
Speed, shallow penetration, and good bead appearance.
Which of the following is true of short-circuiting arc metal transfer in the overhead position?
It has less molten weld pool sag.
Often, FCAW and SAW will have a ____ amperage range than GMAW.
Higher
The ______ of a wire is measured by the diameter of the circle that the wire would make if it were loosely laid on a flat surface.
Cast
With the feed running, adjust the ______ so that the reel stops when the feed stops.
Spoil drag
______ is the chief determinant of how effective a gas is for arc shielding.
Density
The exact shielding gas ______ required for a certain job will vary depending upon the welding conditions.
Flow rate
Because of the constant-potential power supply, the welding current will change as the distance between the _______ and the work changes.
Contact Tip
The _____ refers to the angle between the GMA welding gun and the work as it relates to the direction of travel.
Welding gun angle
Shielding gases in the gas metal arc process are used primarily to protect the molten metal from oxidation and ________.
Contamination.
________ is a thin layer of dark gray or black iron oxide formed during the rolling process.
Mill scale
Filler metals and fluxes usually have ________ added to them so that that adverse effects of the mill scale are reduced or eliminated.
Deoxidizers
Why should wire not be discarded on the floor?
Because it becomes a safety hazard, especially if it gets into the welder.
Why should you do if you need more shielding gas coverage in a windy area?
Put up wind blockers and get the job done as quickly but efficiently as possible.
Explain how high gas flow rates can lead to contamination.
Venturi affect
Describe how to keep the weld bead straight and uniform when visibility is limited.
Keep an eye on the weld pool, sparks and the bead contour.
Explain what happens when spatter falls onto the shielding gas nozzle, and how this can be minimized.
When spatter calls into the nozzle is has higher chances of contaminating the weld, to prevent this, change your work-to-gun angle and lengthen your stick out.
Define GMAW.
Gas metal arc welding is an arc welding process that uses a continuously fed wire and the use of a shielding gas to provide a coalescence between the arc and the work piece without the application of pressure.
In what form is metal transferred across the arc in the axial spray metal transfer method of GMA welding?
It is transferred axially across the arc in hundreds of small droplets.
What three conditions are required for the spray transfer process to occur?
- Argon Shielding Gas
- DCEP
- Transition Current
Why is helium added to argon when making some spray or pulsed-spray transfer welds?
Helium is sometimes added to provide the spray with more of a globular affect. The more helium, the more globular the weld.
Why does DCRP help with welds on metals such as aluminum?
Helps clean the metal.
Why is CO2 added to argon when making GMA spray transfer welds?
CO2 is added because it gives the bead better contour
What may happen if the GMA welding electrode is allowed to strike the base metal outside of the molten weld pool?
It will result in a loud pop and a shower of sparks.
What effect does shortening the electrode extension have on weld penetration?
More penetration and a thicker bead
Describe the weld produced by a backhand welding angle.
Deeper penetration, higher bead contour.
Describe the weld produced by a forehand welding angle.
Less penetration, wider bead contour.
What components make up a GMA welding system?
- Power Source
- Gun
- Wire Feed System
- Shielding Gas with Flowmeter
- Related wires and hoses
- Wire
What parts of a typical GMA welding gun can be replaced?
- Conduit
- Trigger
- Gas Diffuser
- Nozzle
- Contact Tip
The shielding has used on carbon steel when using the short circuit mode of transfer is….
Argon and CO2
Two gases used in the GMAW process that are not inert.
Oxygen and carbon dioxide
