WLD-131 GTAW Study Guide
When welding mild steel, slight changes in the metal have a large effect on the welding skill required
False
If the end of the filler rod is removed from the shielding gas protection, _______.
It will oxidize rapidly
Using a _____ current setting with _____ travel speeds is important when welding stainless steel
Low, faster
The _____ possible gas flow rates and the _____ possible preflow or postflow time can help reduce the cost of welding
Lowest, shortest
______ is inexpensive and requires the least amount of cleaning
Mild steel
Which of the following is true of erosion of the tungsten electrode?
Slow erosion results in limited tungsten inclusions in the weld
Tungsten erosion can be limited by using a water-cooled torch
True
Tungsten is hard but brittle, and has a low impact strength
True
Which of the following is a reason to use GTA welding?
When a close-tolerance, high quality weld is required
Which of the following is true of DCEN?
With DCEN, a pointed tip concentrates the arc
Which of the following is true of breaking and remelting tungsten?
It should be broken squarely
Water hose fittings have _____ threads, and gas hose fittings have _____ threads
Left-hand, right-hand
The gas pre-flow and post-flow times depend on which of the following?
Nozzle size
The most common types of contaminants are _____
Oxides, oils, and dirt
The greater the contamination of the stainless steel weld, _____ of the bead after the weld
The darker the color
Failure to remove tungsten contamination properly will result in _____
The failure of the weld
DCEN concentrates about _____ of its welding heat on the work, and about _____ on the tungsten
2/3, 1/3
When the GTAW process was first developed, argon was the primary shielding gas used
False
The torch may be angled for better visibility, and still have the proper shielding _____
Gas coverage
Which of the following is an inert gas?
Helium
_____ additions are restricted to stainless steels because it is the primary cause of porosity in aluminum welds
Hydrogen
The _____ protects the molten weld pool, the filler rod, and the tungsten electrode as they cool to a temperature at which they will not oxidize rapidly
Postflow period
______ has the poorest heat resistance and electron emission characteristic of all the tungsten electrodes
Pure tungsten
With _____, lack of cleanliness may cause the weld pool to show overheating or poor gas coverage
Stainless steel
______ is somewhat affected by cleanliness, requiring little pre-weld cleaning
Stainless steel
In the GTAW process, contamination left on the metal will be deposited in the weld because______
There is no flux to remove it
_______ Is very well suited for making welds on steel, steel alloys (including stainless), nickel alloys, and most other metals other than aluminum or magnesium
Thoriated tungsten
A steep angle between the torch and the work May draw in air
True
A strong alkaline can be used to chemically clean and point tungsten
True
All three types of welding current can be used for GTA welding
True
Black crusty spots appearing on wild beads are often caused by improper cleaning of the filler rod
True
If the end of the filler rod becomes oxidized it must be cut off before restarting
True
The amperage set on a machine and the actual welding current are often not the same
True
The gas tungsten arc welding process can be used to join nearly all types and thicknesses of metal
True
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
Which of the following is true of tungsten contamination?
Tungsten contamination causes a weak weld and must be cleaned
Which of the following is a way to minimize erosion of the tungsten electrode?
Using DCEN current
Welding power in watts is equal to the ______.
Volts multiplied by amperes
Adding _____ has the same effect on the electrode characteristics as thorium, but is not radioactive
Zirconium
______ electrodes have a current-carrying capacity similar to that of pure tungsten, and maybe used for both AC and DC welding currents
Cerium tungsten
Carbide precipitation occurs in some stainless steels when they are kept at a temperature between _____ degrees Fahrenheit for a long period of time
800 and 1500
One drawback of GTA welding is that welders have an obstructed view of the molten weld pool
False
The molten aluminum weld pool has low surface tension
False
With _____, penetration and bead profile are sensitive to arc length, and the long arcs needed for feeding filler wires are more difficult to control
Helium
Which of the following is true of grinding tungsten electrodes?
If the grinder is used for metals other than tungsten, particles of these metals may become trapped on the tungsten as it is ground, resulting in contamination when the arc is starting
In general the current carrying capacity at DCEN is about _____ than that at DCEP
Ten times greater
Which of the following is true of welding machine settings?
The settings will differ for various sizes and types of tungsten from machine to machine
The improved electron emission of the _____ allows it to carry approximately 20% more current than pure tungsten
Thoriated tungsten
The shielding gas flow rate should be as high as possible
False
In GTA welding, the torch maybe angled _____ for better visibility
0 to 15 degrees from perpendicular
Carbon is the primary alloy in classification of low carbon and mild steel, and ranges from _____ for mild steel
0.15% to .30%
AC concentrates about _____ of its welding heat on the work and _____ on the tungsten
1/2, 1/2
DCEP concentrates ______ of the arc heat on the plate, and _____ of the heat on the electrode.
1/3, 2/3
In GTAW, the arc temperature is around _____ degrees Fahrenheit
11,000
A ______ degree angle or less to the plate surface prevents air from being pulled into the welding zone behind the rod
15
Oxides on _____ May prevent the molten weld pool from flowing together
Aluminum
With ____, cleanliness is a critical Factor
Aluminum
With _____, surface tension helps hold the metal in place, giving excellent bead contour
Aluminum
_____ is denser than air, so it effectively Shields welds and deep grooves in the flat position
Argon
_____ is relatively easy to ionize and thus is suitable for alternating-current applications and easier starts
Argon
An oxide layer on aluminum is _____, while on iron it is ______.
Black, reddish
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
During the manufacturing process, sometimes pockets of primarily _____ gas become trapped inside low carbon and mild steels
Carbon dioxide
Carbide precipitation is the combining of _____
Carbon with chromium
_____ results in welds with deep penetration, and a smaller-size tungsten can be used.
DCEN
_____ produces wide welds with shallow penetration
DCEP
Which of the following is true of DCEP?
DCEP has the highest heat concentration on the electrode tip
As much as 20% of the heat generated by a GTA welding torch does not enter the weld
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
DCEP has the lowest heat concentration on the electrode tip
False
Fused quartz nozzles are no more expensive than ceramic nozzles, but are more easily broken
False
Mild steel is expensive and requires the most amount of cleaning
False
As the gas flows out of the torch it must form a (n) _____ around the weld
Cone protective zone
Exceeding the maximum gas flow rates _____.
Causes weld contamination
The _____ is the cone-shaped sleeve that holds the electrode in the torch
Collet