Chapters 16 welding test
Which of the following is true of breaking and remelting tungsten?
It should be broken squarely
Which of the following is true of erosion of the tungsten electrode?
Slow erosion results in limited tungsten inclusions in the weld
The improved electron emission of the ___ allows it to carry approximately 20% more current than pure tungsten.
thoriated tungsten
Adding ___ has the same effect on the electrode characteristics as thorium, but is not radioactive.
zirconium
DCEN concentrates about ____ of its welding heat on the work, and about ____ on the tungsten.
2/3, 1/3
____ is denser than air, so it effectively shields welds in deep grooves in the flat position.
Argon
Which of the following is true of grinding tungsten electrodes?
If a grinder is used for metals other than tungsten, particles of these metal may be trapped on the tungsten
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
____ results in welds with deep penetration, and a smaller-size tungsten can be used.
DCEN
____ additions are restricted to stainless steels because it is the primary cause of porosity in aluminum welds.
Hydrogen
Water horse fittings have ___ threads, and gas hose fittings have ___ threads.
left-hand, right-hand
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
Tungsten electrodes that contain elements such as lanthanum or yttrium are referred to as ___.
rare earth tungstens
Which of the following is an inert gas?
Helium
___ has the poorest heat resistance and electron emission characteristics of all the tungsten electrodes.
Pure tungsten
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
___ electrodes have a current-carrying capacity similar to that of pure tungsten, and may be used for both AC and DC welding currents.
Cerium tungsten
Which of the following is true of DCEP?
DCEP has the highest heat concentration on the electrode tip
Which type of tungsten electrode does not break evenly when trying to break off contamination?
EWLa-1
____ 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
In GTAW, the arc temperature is around ____ degrees fahrenheit.
11,000
Why is an inert shielding gas required for GTA welding?
To keep the air away from the hot tungsten and molten weld metal
Which of the following is a way to minimize erosion of the tungsten electrode?
Using DCEN current
Which of the following is true of DCEN?
With DCEN, a pointed tip concentrates the arc