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