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Custom Metal Fabrication > Specialty Gas Metal Arc Welding > Flashcards

Specialty Gas Metal Arc Welding Flashcards

1
Q

What is the most common mode of metal transfer when welding base metal that is made of coated steel or stainless steel?

A

Short-circuit transfer

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2
Q

What does GMAW stand for?

A

Gas Metal Arc Welding

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3
Q

What GMAW process is used most for sheet metal work?

A

Short-circuit transfer

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4
Q

What effect does changing the wire speed have on the voltage or amperage of the welding process?

A

The current varies with the amount of wire feed and increases in proportion to the wire speed.

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5
Q

Which organizations have written specifications for GMAW filler metals?

A

AWS and CSA

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6
Q

When using GMAW on mild steel with carbon dioxide shielding, which type of filler wire should be selected?

A

Deoxidized wire

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7
Q

When wires are packaged in sealed containers, what are we protecting them from?

A

Moisture contamination

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8
Q

Improperly stored wires most often produce welds with which defects?

A

Porosity

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9
Q

When welding aluminum you ___ the gun towards the weld?

A

Push

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10
Q

When welding stainless you ___ the gun towards the weld?

A

Pull

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11
Q

Filler metals containing additional deoxidizers are intended for use on which metals?

A

Moderately rusty low-carbon steels

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12
Q

When adding small percentages of oxygen to inert gases like argon, the oxidizing nature of oxygen breaks down surface tension on the molten metal and allows the puddle to?

A

Wet out the edges of the weld bead and minimize undercut in the molten weld.

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13
Q

Which gas is the lightest?

A

Hydrogen

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14
Q

Argon and helium are what kind of gases?

A

Inert gases

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15
Q

Where would you use pure argon shielding gas with GMAW?

A

In the welding of non-ferrous metals such as aluminum, magnesium and their alloys.

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16
Q

What is carbon dioxide gas primarily used for?

A

The welding of mild steel and low alloy steels

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17
Q

What is a characteristic of helium used as a shielding gas when used with short-circuiting metal transfer?

A

A uniform penetration pattern and a broader weld bead result

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18
Q

All GMAW processes need shielding gas. True or False?

A

False

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19
Q

What is the recommended lens shade for a person welding aluminum or stainless steel?

A

They should use the darkest shade that is comfortable, but not lighter than the recommended one.

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20
Q

What is the best material to wear while welding?

A

Heavy denim

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21
Q

What is the best way to prevent sparks from entering your pockets and other entry’s?

A

Keep collars buttoned and pocket flaps and cuffs covered

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22
Q

What must be done to cylinders being stored or transported?

A

They must have their protective caps in place, valves closed, and be stored in the upright position..

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23
Q

What recommended pressure must remain in the depleted cylinder to avoid atmospheric contamination?

A

25 psi residual pressure

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24
Q

What GMAW process is used mostly for welding lighter gauges of sheet metal work?

A

Short-circuit transfer

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25
Q

What determines the type of metal transfer method?

A

The voltage used

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26
Q

What is the recommended flow settings for shielding gas in cfh?

A

25 cfh

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27
Q

What weld defect is not obvious, but very common to the GMAW process?

A

Cold lap

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28
Q

What mixture is best to eliminate the spatter on mild steel?

A

Carbon dioxide and argon

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29
Q

Which gas mixes tend to produce low crowned welds on stainless steels?

A

Argon - helium - carbon dioxide

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30
Q

When 1 percent to 5 percent oxygen is added to argon shielding gas, it is to?

A

Improve wetting action

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31
Q

Improperly stored stainless steel wire most often will produce welds with?

A

Porosity

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32
Q

When you are welding austenitic stainless steels, why must you maintain the moisture content at low levels?

A

Because moisture can cause porosity

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33
Q

What must you do because austenitic stainless steel has a very high coefficient of thermal expansion?

A

You must control distortion by balancing the heat input and minimize joint restraint.

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34
Q

What does MIG stand for?

A

Metallic Inert Gas

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35
Q

What is becoming the main welding process in the sheet metal industry?

A

GMAW

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36
Q

What does GMAW stand for?

A

Gas Metal Arc Welding

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37
Q

What does SMAW stand for?

A

Shielded Metal Arc Welding

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38
Q

Which welding process uses more radiation? GMAW or SMAW

A

GMAW

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39
Q

What is mandatory for all GMAW operations?

A

Adequate ventilation

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40
Q

You must use extreme caution when working with what type of metals that contain these?

A

Zinc, cadmium, lead, and beryllium

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41
Q

Fans or drafts of over ___ surface feet per minute may blow the protective gas envelope away from the weld zone, causing oxidation of the weld metal.

A

50 surface feet per minute

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42
Q

All cylinders must have what attached to it?

A

A WHMIS symbol attached

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43
Q

Which welding process uses a constant voltage (CV) power source that is used to supply a constant voltage no matter what the conditions are and has a wire feed mechanism that feeds wire at a constant rate to the weld zone?

A

GMAW

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44
Q

More voltage requires?

A

Thicker wire and material

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45
Q

More wire being supplied to the weld zone requires?

A

More heat to melt it

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46
Q

What are the 3 basic types of metal transfer methods?

A

Short-circuit transfer, globular transfer, and spray arc transfer

47
Q

Which type of metal transfer methods should be avoided?

A

Globular transfer

48
Q

The welding of steel sheet metal, whether it is coated steel or stainless steel is accomplished through?

A

The short-circuit transfer method

49
Q

Which transfer occurs when the weld metal passes through an open arc in the form of large globules that are often larger in diameter than the filler wire?

A

Globular transfer

50
Q

What transfer occurs when using a direct current electrode positive (DCEP) with a shielding gas containing at least 85 percent argon and by increasing the welding current above a critical value called the transition current?

A

Spray transfer

51
Q

What type of transfer is a stream of tiny metal droplets crossing the welding arc from the filler wire to the base metal?

A

Spray transfer

52
Q

What does DCEP stand for?

A

Direct current electrode positive

53
Q

What does DCEN stand for?

A

Direct current electrode negative

54
Q

Current goes from ____ to ____?

A

Negative to positive

55
Q

The spray transfer method must have no less than ___ percent argon when welding carbon steel?

A

85 percent

56
Q

Voltage set the?

A

Arc length

57
Q

Wire speed sets the?

A

Heat

58
Q

If the voltage is too low or the wire speed is too high, you will get what is referred to as?

A

Stubbing

59
Q

What does FCAW stand for?

A

Flux cored arc welding

60
Q

What is referred to as a semiautomatic welding process?

A

FCAW

61
Q

Which type of welding produces a flux that must be removed, has good weld appearance, and creates smooth uniform welds?

A

FCAW

62
Q

Wires must be identified by?

A

Classification, batch number, wire and spool size

63
Q

What is the purpose of a shielding gas?

A

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

64
Q

The atmosphere is made up of approximately?

A

1 percent argon, 21 percent oxygen, and 78 percent nitrogen

65
Q

What is the thermal conductivity of a gas?

A

It is its ability to conduct heat

66
Q

Argon gas has a low or high thermal conductivity?

A

Low thermal conductivity

67
Q

Helium has a low or high thermal conductivity?

A

High thermal conductivity

68
Q

What is a chemically inert gas that does not combine with the products of the weld zone. It is also a colourless, odourless, non flammable gas that acts as an asphyxiant which can cause suffocation?

A

Argon

69
Q

Argon is approximately ____ times heavier than air.

A

1.4 times

70
Q

Which is better fir welding thin sections? Argon or Helium?

A

Argon

71
Q

What gas is colourless, odourless, non-flammable and is derived from the processing of natural gas?

A

Helium

72
Q

The density of helium is about ___ that of air.

A

0.14 times

73
Q

What gas is used primarily for the non-ferrous metals such as aluminum, magnesium, and copper?

A

Helium

74
Q

Argon gas flow rates are usually set to?

A

20 to 25 cubic ft per hour (cfh)

75
Q

What are referred to as reactive gases?

A

Carbon dioxide, oxygen, hydrogen, and nitrogen

76
Q

What is a compound gas that is reactive, colourless, odourless, non flammable, and acts as an asphyxiant. It’s elements are carbon and oxygen?

A

Carbon dioxide

77
Q

Carbon dioxide is ___ percent heavier than air.

A

53 percent

78
Q

What compound gas is often used for the short-circuiting and globular modes of metal transfer?

A

Carbon dioxide

79
Q

What is currently the cheapest shielding gas available?

A

Carbon dioxide

80
Q

What is a colourless, odourless, oxidizing gas that combines with with nearly all known elements?

A

Oxygen

81
Q

Added oxygen must be less then ___ percent.

A

10 percent

82
Q

What is a colourless, odourless, flammable gas that acts as an asphyxiant and is the lightest known element. It is also highly combustible in air or oxygen. It also burns with an almost invisible flame?

A

Hydrogen

83
Q

What is generally used for special applications such as joining stainless steel?

A

Hydrogen

84
Q

What gas is colourless, odourless, non-flammable, acts like an asphyxiant and is considered inert, but will react with some elements at high temperatures?

A

Nitrogen

85
Q

A widely used ratio of argon to carbon dioxide is?

A

75 percent argon with 25 percent carbon dioxide known as C25

86
Q

Any mixed gas containing ___ is not recommended for non-ferrous metals, as these metals are generally reactive.

A

Oxygen

87
Q

Welders prefer to use backup plates for materials up to?

A

1/4 “ thick

88
Q

What wire diameters are commonly used for the spray process?

A

0.030” and 0.045”

89
Q

What transfer method must be used in order to minimize distortion when welding lighter gauge stainless steels?

A

The short circuit transfer weld mode is used

90
Q

What is of great importance for all types of stainless steel?

A

The need for cleaning prior to and after welding.

91
Q

What causes porosity?

A

Moisture

92
Q

Stainless steel has high or low thermal conductivity?

A

Low thermal conductivity

93
Q

What type of metal has a high coefficient of thermal expansion?

A

Stainless steel

94
Q

What is the most important aspect of welding austenitic stainless steels?

A

The selection of a filler wire having the correct alloy compostition.

95
Q

What is the second most commonly used metal?

A

Aluminum

96
Q

What is the number one commonly used metal?

A

Steel

97
Q

Aluminum is obtained from an ore called?

A

Bauxite

98
Q

What is the thermal conductivity of aluminum?

A

About half that of copper and almost four times higher than that of steel

99
Q

Aluminum requires a heat input ___ times more rapid than mild steel to raise its temperature to the melting point.

A

4 times more

100
Q

What is the melting point of aluminum?

A

660 degrees C (1220 degress F)

101
Q

What type of metal is non-magnetic and is often used to shield electronic equipment. It also does not spark and is used in the fabrication of storage containers?

A

Aluminum

102
Q

What electro-chemical process is used almost exclusively on aluminum?

A

Anodizing

103
Q

Aluminum’s coefficient of expansion is almost ___ that of steel?

A

Twice that of steel

104
Q

To weld aluminum successfully, you must remove the?

A

Oxide layer

105
Q

For MIG welding alumiunum, you need to use a ___ to ___ push travel angle pointed in the direction of travel.

A

10 degress to 15 degrees

106
Q

GMAW is advantageous for welding aluminum material thicknesses greater than?

A

3.2 mm (1/8”)

107
Q

Argon helium mixes are not required until the metal is more than?

A

1” (25mm) thick

108
Q

What welding process is preferred when weld appearance is not a concern?

A

GMAW

109
Q

What are the two types of power sources that can be used for GMAW on aluminum?

A

Constant voltage (CV) and constant current (CC)

110
Q

What power source is most often used for GMAW on aluminum?

A

Constant voltage (CV)

111
Q

Always use 100 percent of what shielding gas for best results on aluminum?

A

Argon

112
Q

What are the two most popular wires for welding aluminum?

A

ER4043 and ER5356

113
Q

What type of wire feeders are commonly used with aluminum?

A

Pull types, push types, or a combination of both

Custom Metal Fabrication (4 decks)

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