Intro to Welding Proc- GTAW quiz study guide

Which of the following is an inert gas? A, Hydrogen B. Oxygen C. Nitrogen D. Helium

D

Penetration

Normally machines are set to 375-385% penetration

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

TIG benefits

-greater control operating -more accurate -stronger welds -allow the arc starts without touching the electrode to work -HF Start only: DC & Inverters -HF off SMAW & scratch start TIG

Which of the following is a way to minimize erosion of the tungsten electrode? A. Using as high a current as possible. B. Using an air-cooled torch. C. Using as small a size of tungsten electrode as possible. D. Using DCEN current.

D

Which of the following is true of grinding tungsten electrodes? A. A grinder should never be used to clean contaminated tungsten. B. The grinder used to sharpen tungsten should have a coarse stone. C. A fine, hard grinding stone will result in more tungsten breakage and a poor finish. D. 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 started.

D

____ is denser than air, so it effectively shields welds in deep grooves in the flat position. A. Helium B. Nitrogen C. Hydrogen D. Argon

D

Foot pedal

Gives power to the machine when the machine is "on," conducting electricity.

____________________ is the time during which gas flows to clear out any air in the nozzle or surrounding the weld zone.

Preflow

shielding gas

Protective gas used to prevent atmospheric contamination.

How TIG welding is commonly used

The TIG machine is commonly operated by a foot pedal.

Collet

cone-shaped sleeve that holds the electrode in the torch.

The ____ possible gas flow rates and the ____ preflow or postflow time can help reduce the cost of welding.

lowest, shortest

____________________ is the time during which the gas continues flowing after the welding current has stopped.

Postflow

Heliarc

utilizing a tungsten electrode and helium as a shielding gas

DC welding properties

-Grind tungsten to conical tip -Conical angle should be 2-3 times tungsten diameter -Do not grind to a sharp point '-Grind parallel to electrode

TIG Welding properties

-Requires constant current power source -Non-consumable tungsten electrode -Requires external shielding gas -Filler rod may or may not be necessary -AC is used for Aluminum and magnesium -DC is used for most other materials -DC+ is rarely, if at all, used

In GTA welding, the torch may be angled ____ for better visibility.

0 to 15 degrees from perpendicular

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

Recommended TIG welding settings (stainless steel)

100 amp, DCEN, HF start only, 3/32 Tungsten, 2% Thor., pure argon

Heat focus

2/3 on work, 1/3 on electrode

Maximum voltage

20 volts

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. A. preflow period B. postflow period C. shielding gas D. nozzle

B

Water hose fittings have ____ threads, and gas hose fittings have ____ threads. A. left-hand, left-hand B. left-hand, right-hand C. right-hand, left-hand D. right-hand, right-hand

B

The ____________________ is the cone-shaped sleeve that holds the electrode in the torch

Collet

AC Balance control

Controls the amount of arc cleaning action and width of the arc etching zone around the weld. Also controls depth of penetration into base material.

AC Frequency control

Controls with of arc cone 60 Hz- soft, wide arc 200 Hz- Narrow, focused arc

DCEN concentrates about ____ of its welding heat on the work, and about ____ on the tungsten. A. 1/3, 2/3 B. 1/4, 3/4 C, 1/2, 1/2 D. 2/3, 1/3

D

Which of the following is true of DCEP?

DCEP has the highest heat concentration on the electrode tip

High frequency

Elevated frequency super imposed over welding current

​Tungsten electrodes that contain elements such as lanthanum or yttrium are referred to as _____.

Rare-Earth tungstens

​Why does the return water on a water-cooled GTAW torch flow out around the power cable?

So a smaller power cable can be used

TIG challenges

TIG welding is a small and compact process; it's hard to see what's going on.

What should be done to the end of the filler rod if it becomes oxidized?

The end of the rod should be cut off.

The most common types of contaminants are ____.

Oxides, oils, and dirt

Wired systems

__________________________________ are more effective

Flowmeters measure the flow rate of a shielding gas in __________units. A. BTU or mm/sec B. CFM or L/min C. PSI or kPa D. GPH or K/min

B

____ results in welds with deep penetration, and a smaller-size tungsten can be used. A. DCEN B. DCEP C. DCRP D. ACHF

A

Why is an inert shielding gas required for GTA welding? A. To keep the air away from the hot tungsten and molten weld metal. B. To help remove the welding fumes to make it easier to see the weld pool. C. It helps to reduce the UV light that can cause skin burns. D. All of the above

A

With ____, penetration and bead profile are sensitive to arc length, and the long arcs needed for feeding filler wires are more difficult to control. A. helium B. nitrogen C. hydrogen D. argon

A

____ has the poorest heat resistance and electron emission characteristic of all the tungsten electrodes. A. Pure tungsten B. Thoriated tungsten C. Zirconium tungsten D. Lanthanum tungsten

A

​The useful life of a ceramic nozzle is affected by the _____________. A. current level and proximity to the work B. tungsten type and shielding gas flow rate C. whether the torch is air or water cooled D. type of current and type of base metal

A

Reverse polarity

A magnetic field opposite to that which exists at present. It strips the oxide layer off the aluminum.

stainless steel

A metal alloy of steel, chromium, and sometimes nickel which is used in casket construction; noted for its ability to resist rust. This makes it a high-quality material.

TIG Welding

Also called gas tungsten arc welding (GTAW), this welding process joins metals by heating them with a tungsten electrode, which does not become part of the completed weld. Filler metal is sometimes used and argon inert gas or inert gas mixtures are used for shielding.

With ____, cleanliness is a critical factor.

Aluminum

TIG Torch

Amperage ranges from 125 to 350 amp.

Which of the following is true of DCEN? A. DCEN concentrates the heat in the tip of the electrode. B. With DCEN, a pointed tip concentrates the arc. C. With DCEN, arc starting with a high-voltage electrical discharge is more difficult. D. With DCEN, the electrode becomes damaged in a short period of time.

B

Which of the following is true of breaking and remelting tungsten? A. It should be melted with a DCEN current. B. It should be broken squarely. C. It should be melted by striking an arc on a piece of carbon. D. It should not be melted by striking an arc on copper, as it will contaminate the tungsten.

B

____ electrodes have a current-carrying capacity similar to that of pure tungsten, and may be used for both AC and DC welding currents. A. Thoriated tungsten B. Cerium tungsten C. Zirconium tungsten D. Lanthanum tungsten

B

____ is very well suited for making welds on steel, steel alloys (including stainless), nickel alloys, and most other metals other than aluminum or magnesium. A. Pure tungsten B. Thoriated tungsten C. Zirconium tungsten D. Lanthanum tungsten

B

AC concentrates about ____ of its welding heat on the work and ____ on the tungsten. A. 1/3, 2/3 B. 1/4, 3/4 C. 1/2, 1/2 D. 2/3, 1/3

C

Adding ____ has the same effect on the electrode characteristic as thorium, but is not radioactive. A. pure tungsten B. cerium C. zirconium D. lanthanum

C

In GTAW, the arc temperature is around ____ degrees Fahrenheit. A. 3,000 B. 6,000 C. 11,000 D. 17,000

C

What material should shielding gas hoses be made of? A. Rubber B. Copper C. Plastic D. Any material is fine: the gas is inhert

C

____ additions are restricted to stainless steels because it is the primary cause of porosity in aluminum welds. A. Helium B. Nitrogen C. Hydrogen D. Argon

C

​How must tube- and ball-type flowmeters be mounted? A. horizontally B. on a solid surface C. vertically D. Between 5 ft and 5.5 feet above the floor

C

​What is the purpose of a gas lens? A. It helps to see the molten weld pool by magnifying it. B. It filters out most of the harmful UV and some of the IR light. C. It reduces the turbulence in the shielding gas. D. It filters out dust and dirt that might be in the shielding gas due to a dirty shielding gas hose.

C

____________________ is a by-product of the natural gas industry. It is removed from natural gas as the gas undergoes separation for purification or refinement.

Helium

shielding gas' main issue

If you melt the filler metal, the shielding gas will oxidize it.

Argon and helium are _________________________ gases, which means they will not combine chemically with any other material, and will not affect the molten weld pool in any way.

Inert

The ____________________ directs the shielding gas directly on the welding zone.

Nozzle

How must tube- and ball-type flowmeters be mounted?

Vertically

Which of the following is a reason to use GTA welding?

When a close tolerance, high-quality weld is required.