GTAW Flashcards

1
Q

The word ‘TUNGSTEN’ refers to what?

A

The pure element

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2
Q

Tungsten’s melting point is…

A

6170 degrees Fahrenheit

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3
Q

All GTAW electrodes start with the letters…

A

EW

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4
Q

The ‘E’ stands for…

A

Electrode

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5
Q

The ‘W’ stands for…

include the German name as well

A

Tungsten

From Wolfram, which is German for tungsten

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6
Q

Electrodes are further identified by the element with which they are alloyed. Identify the following by what they stand for…

Th...
La...
Ce...
Zr...
P...
A

Th…Thoriated

La…Lanthanated

Ce…Ceriated

Zr…Zirconiated

P…pure

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7
Q

EWla-1.5%

In the electrode classification above what does the 1.5% stand for?

A

Indicated the percentage of element that is in the electrode…

1.5% lanthanated

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8
Q

The key material GTAW electrodes are comprised of…

A

Tungsten

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9
Q

GTAW electrodes with a red color code indicate:

A. Pure tungsten
B. 1.7% - 2.2% Thoriated
C. 1.3% Lanthanated
D. 1.8% -2.2% ceriated

A

B. 1.7% - 2.2% Thoriated

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10
Q

GTAW electrodes come in diameters of:

1/8”
0.040”
5/32”
All of the above

A

All of the above

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11
Q

What type of electrode is EWP?

Color code?

Current?

Perfect for welding on what kind of material?

A

Pure

Green

AC

Aluminum

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12
Q

What electrode type is EWCe-2?

Color code?

Current?

A

2% Ceriated

Orange

DCEN, AC

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13
Q

What electrode type is EWLa-1?

Color code?

Current?

A

1% Lanthanated

Black

DCEN, AC

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14
Q

What electrode type is EWLa-1.5%?

Color code?

Current?

A

1.5% Lanthanated

Gold

DCEN, AC

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15
Q

What electrode type is EWLa-2%?

Color code?

Current?

A

2% Lanthanated

Blue

DCEN, AC

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16
Q

What electrode type is EWZr-1?

Color code?

Current?

A

1% Zirconiated

Brown

AC

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17
Q

What electrode type is EWTh-1?

Color code?

Current?

A

1% Thoriated

Yellow

DCEN, Inverter AC

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18
Q

What electrode type is EWTh-2?

Color code?

Current?

A

2% Thoriated

Red

DCEN, Inverter AC

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19
Q

What electrode type is EWG?

Color code?

Current?

A

General

Gray

Manufacturer Specified

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20
Q

GTAW electrodes with a green color code indicate:

A

Pure tungsten

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21
Q

EWP electrodes contain a minimum of _____ tungsten, with no additional __________ ___________.

A

99.5%

Alloying elements

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22
Q

EWP (pure tungsten) provides good _____ __________ when used with _________ current.

A

Arc stability

AC current either balanced-wave or continuous high frequency

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23
Q

The tip of the EWP electrode maintains…

A

A clean, balled end that promotes good arc stability

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24
Q

EWP electrodes are usually used with AC but may also be used with ______ but doesn’t provide the arc initiation and arc stability characteristics

A

DC

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25
Q

EWP electrodes are generally used for welding what?

A

Aluminum and Magnesium alloys

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26
Q

EWTh electrode characteristics include

A

Easy are starting
Excellent arc performance
Long service life
Withstands high amps

Note: contains Thoria which is radioactive.

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27
Q

EWLa electrode characteristics include:

A

Easy arc start
Arc stability
Good service life

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28
Q

What is the best non-radioactive alternative to EWTh-2 electrodes?

A

EWLa-1.5

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29
Q

ELa-2 is better suited for ________ ________ __________ and numerous _____________.

A

Short weld cycles

Re-ignitions

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30
Q

GTAW electrode that offers the best performance and longevity for welding higher current mild steel in DC - polarity

A

1.7% - 2.2% Thoriated

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31
Q

If the amount of current used exceeds the capability of the electrode (diameter), tungsten inclusions in the weld may result. This can be identified with radiographic inspection and is known as:

A

Tungsten spitting

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32
Q

As a general rule, the inside diameter of the gas nozzle should be a minimum of:`

A

3x the diameter of the electrode

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33
Q

Tungsten boasts the highest melting point of any metal:

A

6191 degrees Fahrenheit

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34
Q

The AWS standard that guides GTAW electrodes is:

A

A5.12

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35
Q

AWS GTAW electrode classification EWG:

A. Zirconiated
B. Rare earth tungsten(varies per manufacturer)
C. Ceriated
D. Pure tungsten

A

Rare earth tungsten

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36
Q

AWS GTAW electrode color classification EWP:

A

Green

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37
Q

EWTh electrodes are superior to EWP electrodes in several ways:

A
Higher current capacity
Longer life
Greater resistance to contamination of the weld
Arc starting is easier
More stable arc
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38
Q

EWTh electrodes maintain what kind of tip?

A

Sharpened

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39
Q

Sharpened tips are desired for __________ welding operations

A

DCEN

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40
Q

Electrode tip preferred for AC welding:

A

Balled end

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41
Q

Compared to EWP electrodes, the EWCe electrode advantages are:

A

Facilitate arc starting
Improve arc stability
Reduce rate of vaporization or burn-off
Work well with either AC/DC polarity

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42
Q

AWS GTAW electrode classification with excellent low amperage arc staring:

A

EWP

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43
Q

Electrodes that can be used as a non-radioactive substitute for EWTh-2

A

EWLa-1
EWLa-1.5
EWLa-2

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44
Q

EWZr electrode advantages v.s pure tungsten

A

Arc stability and starting
Recommended over EWP for radiographic-quality weld on aluminum and magnesium
Balls up easier
Higher resistance to contamination

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45
Q

With AC welding, EWP or EWZr electrodes form a _______ ______.

A

Balled end

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46
Q

With DC welding, EWTh, EWCe and EWLa electrodes are usually used, and the electrode end is usually ground to a specific included angle and is often __________.

A

Truncated

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47
Q

Small-diameter electrodes can be used with a _________ ____________ preparation for _______ welding

A

Square end

DCEN

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48
Q

Tungsten tips are generally prepared by:

A

Grinding
Balling
Chemical sharpening

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49
Q

What are the 3 main advantages of GTAW electrodes

A

One of the highest melting points of all metals @ 6170’ F

Low electrical resistance

Good heat conductivity

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50
Q

If tungsten spitting occurs:

A

Change the type of electrode
Use a larger diameter electrode
Decrease the welding current

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51
Q

GTAW-P is usually applied with electrode negative(DCEN)

TRUE OR FALSE

A

TRUE

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52
Q

Generally, the GTAW-P adjustments are pre-set in the power source with the minimal adjustability from the operator.

True of false

A

False

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53
Q

PPS stands for:

A

Pulses per second

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54
Q

In pulsed DC welding, the pulse current level is usually set at:

A

2-10x the background current

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55
Q

Advantages of pulsed current include:

A

Greater penetration

Minimizes distortion

Equal penetration to joints with dissimilar metal thicknesses

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56
Q

Ceriated tungsten requires special precautions due to radioactive dust concerns

True or false

A

False

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57
Q

When it come to shielding gas flow, more is better

True or false

A

False

58
Q

Use the heat of the arc to melt the arc

True or false

A

False

59
Q

A grinding wheel dedicated to sharpening tungsten electrodes is essential to prevent______________

A

Contamination

60
Q

A __________ point is recommended for AC welding of aluminum. This provides better __________ __________

A

Blunted

Directional control

61
Q

A _______ _______ uses a mesh screen to distribute the shielding gas more evenly

A

Gas lens

62
Q

As a general rule, tungsten extension should NOT exceed the _______ _______ of the cup or nozzle

A

Inside diameter

63
Q

On material prone to ________, such as thin gauge stainless steel, use additional tacks

A

Warping

64
Q

The preferred GTAW technique to melt filler metal is to touch the end of the _____ _____ to the leading edge of the ______ ______

A

Filler rod

Molten(weld) pool

65
Q

Torches are rated in accordance with the max. _________ that can be used without overheating.

A

Current

66
Q

GTAW torched for manual applications are designed:

A

With a head angle of 120 degrees
Adjustable angle heads
With 90 degree or straight heads

67
Q

The heat generated in a GTAW torch during welding is removed by:

A
A. Gas cooling
B. Water cooling
C. Both
D. None
Look it up
68
Q

Gas cooled(air cooled) torches are limited to welding currents of

A

200A

69
Q

Water cooled GTAW torches can run continuously at currents reaching ________.

A

?

70
Q

________ or patterned jets incorporated into the torch body to feed shielding gas into the nozzle

A

Diffusers

71
Q

Gas nozzles are made of various ____ _____ materials ranging in different shapes, diameters and lengths

A

Heat resistant

72
Q

The least expensive but most brittle GTAW nozzles:

A

Ceramic

73
Q

_______ _______ contain a porous barrier diffuser and are designed to fit around the electrode or collet.

A

Gas lenses

74
Q

Gas lenses produce a longer, undisturbed flow of shielding gas and enable operators to weld with the nozzle ________ inch or more from the workpiece

A

1 inch

75
Q

Pulsed current is useful for welding stainless steel because it

A

Produces less heat input that a steady current

76
Q

Shielding gas flow rates should be decreased when welding in the overhead position

True or false

A

False

77
Q

When the GTAW power source is set to DCEP…

A

Most of the heat is directed toward the electrode

78
Q

Which of the following methods is used to start GTAW arc without touching the base metal?

—high frequency start
—lift start
—scratch start
—pulse start

A

High frequency start

79
Q

High frequency currents is added to alternating current to…

A

Maintain the arc

80
Q

It’s not necessary to keep the hot end of the filler wire in the gas-shielding zone

True or false

A

False

81
Q

AC is used for welding aluminum because…

A

Of the cleaning action and medium penetration of the arc

82
Q

When using GTAW to weld aluminum with AC, the tip of the tungsten electrode should be…

A

Rounded at the tip

83
Q

The shielding gas most commonly used for welding low carbon steel with GTAW is…

A

Argon

84
Q

Which is not an advantage of GTAW?

—all pos. Welding
—very little spatter and post-weld cleaning
—high quality welds in a great variety of metals
—high deposition rate

A

High deposition rate

85
Q

What approximate percentage of the heat of the arc is directed toward the electrode when welding with DCEP

A

70%

86
Q

Pulsed current is useful for welding out of position because

A

The weld pool is easier to control

87
Q

How long should the post purge (shielding gas) be allowed to flow after the welding arc is broken?

A

Long enough to allow the base metal and the electrodes to cool

88
Q

Chemical symbol for tungsten is

A

W (wolfram)

89
Q

The voltage present when the welding machine power switch is in the ON position, but no welding is taking place is called

A

Open-circuit voltage

90
Q

Filler metal with an AWS classification of ER4043 is used to weld…

A

Aluminum

91
Q

Copper coated mild steel filler metals used for oxyacetylene welding are also recommended for GTAW

True or false

A

False

92
Q

Color brown is associated with what type of tungsten electrode?

A

Zirconiated

93
Q

Color black is associated with what type of tungsten electrode?

A

Lanthanated

94
Q

Color red is associated with what type of tungsten electrode?

A

2% thoriated

95
Q

Color green is associated with what type of tungsten electrode?

A

Pure

96
Q

Color yellow is associated with what type of tungsten electrode?

A

Thoriated

97
Q

Color orange is associated with what type of tungsten electrode?

A

Ceriated

98
Q

Filler metal with an AWS classification of ER308 is used to weld…

A

Stainless steel

99
Q

Filler metal with an AWS classification of er4043 is used to weld:

A

Aluminum

100
Q

Filler metal with an AWS classification of er308 is used to weld

A

Stainless steel

101
Q

GTAW is…

A

An arc welding process in which shielding gas protects the arc between a non consumable tungsten electrode and a base metal.

102
Q

High frequency

A

Is high voltage, low current pulses over 16,000 cycles per second. Is used to start an arc without touching an electrode to the work.

103
Q

DC

A

Is an electrical current that flows in one direction only

104
Q

GTAW machines are _______ current power sources.

A

Constant

105
Q

What current has the quality of both DCEN & DCEP and is used for aluminum and magnesium?

A

AC

106
Q

Filler metal rods usually come in _____” lengths

A

36

107
Q

A GTAW electrode is held in the torch by a…

A

Collet

108
Q

A short ____ and electrode permit use of torches in difficult-to-reach places

A

Cap

109
Q

What 2 types of electrodes are preferred when AC is used for a GTAW project?

A

Pure

Zirconiated

110
Q

Which method of starting a GTAW arc involves touching an electrode to the base metal, then withdrawing about 1/8”?

A

Touch starting

111
Q

What kind of arc can cool a weld in the overhead position?

A

Pulsed

112
Q

What is the most common power source used for GTAW

A

Transformer-rectifier

113
Q

What is the MAX. Size of the electrode balled tip compared to the diameter of the electrode?

A

1 1/2 size the diameter

114
Q

Which of the following methods is used for starting a GTAW arc?

A

High-voltage

115
Q

In which of the following 2 GTAW positions should you weld using the lowest possible surrender settings?

A

Vertical and overhead

116
Q

InDCEN

A

Elektron flow from the electro to the work piece

117
Q

DCEP

A

Electron’s flow from the work piece to the electros along with about 70% of the heat

118
Q

Alternating current

A

Is an electrical current that has alternating positive and negative values

119
Q

Conventional sine wave transformer rectifier

A

Is a well power source that produces a sinusoidal waveform

120
Q

Sinusoidal waverform

A

Is a 60 cycle per 2nd sine wave. It is considered balance because it has equal amounts of electro positive current and electro negative current

121
Q

Conventional square wave transformer rectifier

A

Is a welding power source that produces a relatively square 60HZ Wave form . It provides 3 advantages the 1st is the change from positive to negative is immediate resulting in a smoother Ark.. Sag in, a conventional square wave form is more efficient than a sine wave because the Ark. Spends more time at peak EP for cleaning and peak EN and for penetration.
3rd, a conventional square wave has an adjustable balance

122
Q

Conventional square wave transformer rectifier ratio of cycle time

A

Approximately 30% cleaning action and 70% penetration to 5 5% cleaning action and 45% penetration

123
Q

Inverter

A

Is a welding power source that produces a true square AC Wave form

124
Q

Argon helium mixtures

A

Helium produces an increase teeth and put in a deeper penetration required to wild thicker material while Oregon aids in arc starting helps to stabilize the Ark. And provide cleaning action

125
Q

Post flow

A

Is the shielding gas after the arc is extinguished

126
Q

Argon

A

Smooth at Ark. At Lord Ambridge and voltage settings, easy art starting, heavier-than-air which means lower gas flow rates, better cleaning action, less expensive

127
Q

Helium

A

Is lighter-than-air which means that it requires higher flow rates to provide adequate coverage And higher ionization potential which means arik starting is harder it is also more expensive

128
Q

GTAW-P

A

Pulsed GTAW Is a gas tungsten Ark. Welding variation in which direct current is pulsed Between A peak current and a background current

129
Q

PPS

A

Pulses per 2nd is the number of times per 2nd that current Achieves peak current

130
Q

Stainless Steals are of the what series

A

Three hundred

131
Q

Stainless steels are commonly welded with what using what

A

GTAW

DCEN, EQUIPPED WITH HIGH FREQUENCY

132
Q

GTAW Is particularly adaptable for welding what

A

Thin-gauge Stainless steel and high pressure stainless steel piping

133
Q

The procedure for welding all types of stainless steel

A

Is the same. Filler metals for welding stainless steels are alloyed To prevent cracking. Welding parameters such as proper current, electro diameter, shielding gas flow rate, and filler metal diameter should we set based on thickness of stainless steel

134
Q

Aluminum

A

Nonferrous metla

135
Q

Heta treatable aluminum alloys above _____ are not weldable

A

7039

136
Q

Contaminants such as oil and grease should be removed by wiping the surface with a suitable cleaner.________ Is commonly used on aluminum

A

Acetone

137
Q

With aluminum, best results are obtained by using____ current with _______ as a shielding gas

A

AC

Argon

138
Q

When welding aluminum

A

What link premitur such as current, electro diameter, argon flow rate, and filler metal diameter are based on the thickness of the aluminum and the welding position

139
Q

Aluminum and magnesium both have what

A

High thermal conductivity, low melting points, high thermal expansion, and rapid oxidation

140
Q

DCENs heat balance in the arc

A

70% at the work end, 30% at the electrode end

141
Q

DCEPs heat balance in the arc

A

70% workpiece, 30% electrode

142
Q

ACs heat balance in the arc

A

70% workpiece, 30% electrode