GMAW FILLER METALS, SHIELDING GASES, AND SAFETY 120103B

Question 0

Which organizations have written specifications for GMAW filler metals?
A) WCB and CSA
B) CWB and AWS
C) ASME and CWB
D) AWS and CSA

Answer 0

D. AWS and CSA have written specifications for GMAW filler metals.

Question 1

The composition of the base metal is the major factor to consider when selecting:
A) a shielding gas
B) filler materials
C) a power source
D) current settings

Answer 1

B. The composition of the base metal is a major factor to consider when selecting filler metals.

Question 2

Silicon, aluminum and manganese, when added to ER49S-2 are used as:
A) stabilizers
B) deoxidizers
C) lubricators
D) indicators

Answer 2

B. Silicon, aluminum, and manganese are used as deoxidizers when added to ER49S-2.

Question 3

With GMAW wire, cast refers to the:
A) circle formed by one wrap of the wire
B) method of forming the wire
C) natural twisting action of the wire during forming
D) ability of the wire to be pushed through a plastic liner

Answer 3

A. Cast refers to the circle formed by one wrap of the wire.

Question 4

Describe the helix of a wire and the effect that it may have on welding.

Answer 4

Helix is the result of the natural twisting action of the wire during forming. If the helix of the wire is excessive, the wire does not exit straight out through the contact tip. This in turn can cause the wire to wander. The arc becomes unstable as this corkscrew effect causes a change in the direction of wire feed.

Question 5

Interpret the ER49S-2 electrode classification:
E:
R:
49:
S:
2:

Answer 5

E: electrode
R: rod
49: minimum as welded tensile strength and megapascals divided by 10.
S: solid wire
2: chemical analysis

Question 6

When using GMAW on mild steel with carbon dioxide shielding, which type of filler wire should be selected?
A) an oxidized wire
B) a deoxidized wire
C) a high alloy wire
D) a flux coated wire

Answer 6

B. A deoxidized wire.

Question 7

When wires are packaged in sealed containers, it is merely to protect them from:
A) smoke and fumes
B) moisture contamination
C) transportation damage
D) ultraviolet light radiation

Answer 7

B. Moisture contamination.

Question 8

Improperly stored wires most often produce welds with:
A) wagon tracks
B) cold lapping
C) slag inclusions
D) porosity

Answer 8

D. Porosity

Question 9

Filler metals containing additional deoxidizers are intended for use on:
A) moderately rusty low carbon steels
B) alloy steels containing chromium
C) nonferrous metals
D) stainless steels with more than 18% chromium

Answer 9

A. Moderately rusty low carbon steels.

Question 10

What does the G stand for in the CSA GMAW electrode classification
ER49S-G?
A) gas shielded
B) general classification for new electrodes not covered under any other classification
C) approved for use on class G secondary containment vessels for nuclear service
D) general-purpose electrode for use on carbon and low alloy steels

Answer 10

B. General classification for new electrodes not covered under any other classification

Question 11

What is the primary purpose of a shielding gas?

Answer 11

To prevent the molten weld metal from absorbing elements from atmospheric air, such as oxygen and nitrogen.

Question 12

When oxygen and nitrogen from the atmosphere become mixed in the molten weld metal, they:
A) increase the tensile strength of the weld metal
B) form harmful oxides and nitrides in the weld metal
C) help increase the ductility of the weld zone
D) increase the fracture toughness of the weld metal

Answer 12

B. Form harmful oxides and nitrides in the weld metal.

Question 13

Which gas is the lightest?
A) hydrogen
B) argon
C) helium
D) oxygen

Answer 13

A. Hydrogen.

Question 14

Argon and helium are:
A) reactive gases
B) inert gases
C) ionized gases
D ) nonconductive gases

Answer 14

B. Inert gases.

Question 15

Where would you use pure argon shielding gas with GMAW?

Answer 15

In the welding of nonferrous metals such as aluminum, magnesium, copper and their alloys.

Question 16

What is carbon dioxide gas primarily used for?

Answer 16

For welding of carbon steels.

Question 17

List three factors to consider when selecting a gas for GMAW.

Answer 17

A) base metal
B) cost of the gas
C) quality required
D) joint design
E) joint position
F) type of metal transfer
G) jigging and fixturing

Question 18

Is carbon dioxide a monatomic gas or a compound gas?

Answer 18

A compound gas.

Question 19

A characteristic of carbon dioxide shielding gas used with short-circuiting metal transfer is:
A) a deep, narrow penetration pattern
B) high weld metal loss in the form of 
spatter
C) excellent surface cleaning action
D) a shallow, wide penetration pattern

Answer 19

B. High weld metal loss in the form of spatter.

Question 20

Which modes of metal transfer are possible with GMAW using .9 mm (0.035") mild steel wire and carbon dioxide shielding gas?
A) spray and globular
B) globular and short circuiting
C) short circuiting and pulse spray
D) spray and pulse spray

Answer 20

B. Globular and short circuiting.

Question 21

The addition of oxygen to argon causes the temperature of the molten metal to:
A) decrease
B) increase
C) stabilize
D) oxidize

Answer 21

B. Increase.

Question 22

Compared to carbon dioxide, argon is an excellent shielding gas for GMAW because it allows the use of:
A) spray metal transfer
B) globular metal transfer
C) short circuit metal transfer
D) low gas flow rates in globular transfer

Answer 22

A. Spray metal transfer.

Question 23

When 1% to 5% oxygen is added to argon shielding gas, it is to:
A) reduce spatter
B) increase the deposition rate
C) improve wetting action
D) reduce welding costs

Answer 23

C. Improve wetting action.

Question 24

Which of the following gas mixes tends to produce low crowned weld beads on stainless steels?
A) helium-carbon dioxide
B) argon-carbon dioxide
C) nitrogen-carbon dioxide
D) argon-helium-carbon dioxide

Answer 24

D. Argon-helium-carbon dioxide.

Question 25

List three advantages of GMAW.

Answer 25

A) lower skill requirements then SMAW
B) excellent for light gauge metals
C) good arc control when working with poor fit-ups
D) less heat input means less distortion than SMAW
E) high production rates
F) no slag to remove, little or no post weld cleanup

Question 26

List three disadvantages of GMAW.

Answer 26

A) special equipment required resulting in higher initial cost
B) equipment requires more maintenance and downtime
C) lack of fusion can be a problem
D) cannot be used outdoors or in drafty locations
E) high radiant energy requires protection for the welder and others in the vicinity
F) wire feeder must be in close proximity to welding

Question 27

What color should your protective clothing be when welding with GMAW and why?

Answer 27

Clothing should be dark to reduce reflected light radiation.

Question 28

Name two toxic gases that can be created from the ultraviolet light produced from welding.

Answer 28

Ozone and phosgene gas (from chlorinated hydrocarbon degreasers).

Question 29

Is it advisable to weld with any arc welding process under wet conditions?
Explain.

Answer 29

When you are exposed to wet weather conditions, or are standing on wet surfaces, protect yourself from electrical shock hazards by wearing rubber boots with dry socks and rubber gloves.

Question 30

The use of shielding gases for GMAW increases the need for:
A) good lighting
B) good ventilation
C) good heat shielding
D) better eye protection

Answer 30

B. Good ventilation.

Question 31

How can the air-quality be affected when welding with the process that uses a shielding gas?

Answer 31

Shielding gases in sufficient quantities will displace enough air to render the work area oxygen deficient. Dizziness or a feeling of euphoria is usually the first sign of oxygen deficiency and precautions must always be taken to ensure adequate breathing air is supplied.

Question 32

High ultraviolet radiation emissions from GMA W can cause atmospheric oxygen in the vicinity of the arc to convert to:
A) ozone
B) carbon monoxide
C) carbon dioxide
D) argon

Answer 32

A. Ozone.

Question 33

A potential source of poisonous chemical fume when welding is:
A) inert shielding gases
B) chlorinated degreasing solvents
C) carbon dioxide extinguishers
D) anti-spatter nozzle sprays

Answer 33

B. Chlorinated degreasing solvents.