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Question 1

What positions can be welded when using the GTAW process?

Answer 1

All positions.

Question 2

What is an advantage of TIG when referring to post weld cleaning?

Answer 2

Post weld cleaning is reduced.

Question 3

Can current be adjusted during the TIG welding process?

Answer 3

Yes.

Question 4

What weldments does the TIG process produce?

Answer 4

Low-hydrogen weldments.

Question 5

What is the after affect of distortion, corrosion, and ductility, after the TIG welding process?

Answer 5

Less distortion, more ductile, more corrosion resistant.

Question 6

What are some disadvantages to GTAW?

Answer 6

Cost
Pre cleaning
Skill learning

Question 7

What type of shielding gas is required for TIG?

Answer 7

Inert shielding gases.

Argon, helium etc.

Question 8

At what material point thickness does GTAW have issues welding?

Answer 8

More than 10mm (3/8”)

Question 9

What is the effect of excessive torch angle?

Answer 9

Air entrainment, porosity.

Question 10

Explain air entrainment.

Answer 10

Air entrainment is caused by excessive torch angle. The air is sucked into the weld zone causing problems such as porosity.

Question 11

At what degree does air entrainment become an issue.

Answer 11

> 35°.

Question 12

How does one maintain adequate gas shielding during the GTAW process?

Answer 12

Smaller stick out.

Question 13

How is it possible for a welder to use a larger nozzle-to-work distance?

Answer 13

With the use of a gas lens. The shielding gas is projected a greater distance making is possible for longer electrode stick out.

Question 14

For thin materials, what is the appropriate stick out?

Answer 14

3-5mm.

Question 15

For thick materials, what is the appropriate stick out?

Answer 15

8-10mm.

Question 16

What is the preferred option when purging?

Answer 16

Solar flux.

Question 17

What benefit comes with using Solar Flux?

Answer 17

It protects the backside of the piece from oxides as well as supports the molten weldment.

Question 18

What does Solar Flux help prevent besides oxidation?

Answer 18

Burn-through.

Question 19

Does Solar flux help control penetration?

Answer 19

Yes.

Question 20

What must be done for multi-pass welds when using Solar Flux?

Answer 20

Solar flux is preferred for single pass welds. For multi-pass welds, the flux needs to be re-applied before each pass and the application time of such is increased.

Question 21

What type of Solar Flux is specifically designed for stainless steels?

Answer 21

Solar Flux B.

The exception is stainless steels containing nickel.

Question 22

What is the purpose of a gas lens?

Answer 22

For some torches, the flow of shielding gas from the gas cup can become finicky. When a torch is fitted with a gas lens, the shielding gas coverage of the weld is improved by creating laminar flow, preventing turbulence.

Question 23

What are gas lenses made of?

Answer 23

Multiple layers of fine mesh screening designed to fit the tungsten electrode or collet.

Question 24

Is a tungsten electrode considered a consumable?

Answer 24

No.

Question 25

What is the melting point of tungsten?

Answer 25

3410° C (6170° F).

Question 26

What is the difference between alloyed tungsten electrodes apposed to other non-alloyed tungsten electrodes?

Answer 26

Alloyed electrodes have a higher melting point. Meaning they have a higher current capacity.

Question 27

When welding aluminum, what is a particular concern?

Answer 27

The creation of ozone.

Question 28

How is ozone produced?

Answer 28

The UV radiation emitted from GTAW can produce ozone (O3) from the oxygen in the surrounding air.

Question 29

Why should one be wary of ozone?

Answer 29

It is highly toxic and chemically reactive. It can cause severe lung and tissue damage, headaches, dryness of eyes, irritation of nose and throat.

Question 30

What are shielding gas flow rates dependent on?

Answer 30

Gas nozzle outlet size Weld joint design Material Current Drafts, ie. wind Travel speed and position Shielding gas.

Question 31

What is the outcome of excessive gas flow rates?

Answer 31

Waste of gas and turbulence resulting in weld contamination.

Question 32

What is the outcome of little gas flow rates?

Answer 32

Oxidization and porosity due to lack of coverage.

Question 33

How do gas flow rates and cups correspond?

Answer 33

The larger the nozzle (cup) the higher the flow rate can be without the effect of turbulence.

Question 34

What is the gas flow rate of shielding gas for argon?

Answer 34

5-15 Ipm (10.5-31.5 cfh).

Question 35

At what distance does high frequency arc starting occur?

Answer 35

within about 5mm of the workpiece. This high frequency closes the gap between the two.

Question 36

What is a drawback of high frequency GTAW?

Answer 36

It can be quite noisy depending on the frequency range. It can also interfere with electronic devices such as pace makers.

Question 37

What type of brush or wire wheel should be used when cleaning stainless steel?

Answer 37

Stainless steel bristle or wire.

Question 38

How does one avoid cross contamination of tools when handling stainless steel?

Answer 38

Only use tools dedication to stainless and stainless **only**.

Question 39

What should be done prior to welding stainless steel?

Answer 39

Clean off dirt and grease.

Question 40

What type of shielding gas should not be used to weld on stainless steel?

Answer 40

100% CO2.

Question 41

What is the most common current and polarity used for GTAW?

Answer 41

DCEN aka straight polarity.

Question 42

What percentage of the heat from the arc is released into the workpiece?

Answer 42

70%.

Question 43

What is a characteristic of DCEN?

Answer 43

Deep penetration, narrow beads.

Question 44

Does DCEN have any cleaning action?

Answer 44

No. Unlike AC or DCEP, DCEN does not have any cleaning action.

Question 45

With DCEP 70% of the heat from the arc is released where?

Answer 45

Into the electrode.

Question 46

What is a characteristic of DCEP?

Answer 46

Reduced penetration, wide beads. Reduced tungsten life.

Question 47

Which current requires a larger tungsten?

Answer 47

DCEP.

Question 48

Does DCEP have any cleaning action?

Answer 48

Yes. Both DCEP and AC current have cleaning action due to the flow of electrons. This is useful for welding aluminum.

Question 49

When is AC current needed?

Answer 49

When the advantages of DCEN polarity and the cleaning action of DCEP are needed.

Question 50

What are the most common power sources of GTAW?

Answer 50

Transformer/rectifier. This is because they can produce both AC and DC current.

Question 51

What are two characteristics of an inverter?

Answer 51

Higher cost, greater electrical efficiency.

Question 52

How is the shielding gas supply controlled?

Answer 52

With the use of a flowmeter regulator.

Question 53

What does a flowmeter regulator do?

Answer 53

Reduces cylinder pressure and controls gas flow.

Question 54

Why are two-stage regulators recommended apposed to single?

Answer 54

For precision and high volume applications.

Question 55

What is the typical outlet pressure to a flowmeter?

Answer 55

40-60 psi (276-414 kPa)

Question 56

How do some tungsten electrodes have a round/balled end?

Answer 56

Some electrodes have a round/balled end due to establishing an arc for a short interval of time while running AC or DCEP current. This is simply the electrode melting at the tip.

Question 57

When are rounded/balled tipped electrodes used?

Answer 57

This shape is often used for welding on materials that require cleaning action.

Question 58

What position should the tungsten be held to produce a round/balled end?

Answer 58

Vertically.

Question 59

What shape of tungsten should be used when using DCEN?

Answer 59

Tapered or pointed end.

Question 60

What position should tungsten be ground?

Answer 60

Lengthwise. AKA grinding marks should go along with the length of the electrode.

Question 61

What is something to consider when using thoriated tungsten?

Answer 61

It is radioactive (on a low level).

Question 62

What are pure tungsten electrodes mainly used for?

Answer 62

AC welding of aluminum.

Question 63

What colour and classification is pure tungsten?

Answer 63

Green. EWP.

Question 64

What is a recommended alternate to thoriated tungsten?

Answer 64

Lanthanated tungsten or E3 tungsten.

Question 65

What safety steps should be used when using thoriated tungsten?

Answer 65

Avoid breathing in dust generated by grinding.

Question 66

Why is porosity such an issue in the GTAW process?

Answer 66

Due to the puddle forming to quickly, gases do not have a chance to escape.

Question 67

How can the issue of porosity be solved using filler rods?

Answer 67

Using a deoxidized filler rod. Ie. A thin copper coating.

Question 68

For mild steel, what filler rod should be used?

Answer 68

ER70S-X.

Question 69

In the filler rod ER70S-X what does the ER represent?

Answer 69

Electrode Rod

Question 70

In the filler rod ER70S-X what does the 70 represent?

Answer 70

Minimum tensile strength in ksi.

Question 71

In the filler rod ER70S-X what does the S represent?

Answer 71

Filler metal is solid

Question 72

In the filler rod ERS70S-X what does the X represent?

Answer 72

Indicates chemical composition of solid electrode

Question 73

What is the affect of a longer arc?

Answer 73

Wide shallower beads.

Question 74

What is the affect of a short arc?

Answer 74

Deep narrow bead.

Question 75

What times the electrode diameter can the arc length be adjusted?

Answer 75

1.5 times.

Question 76

What does the Collet Body do?

Answer 76

Creates an electrical contact between the collet and torch body.

Question 77

How are tungsten electrodes held in the collet?

Answer 77

Through the use of friction and pressure.

Question 78

How can collets be damaged?

Answer 78

When paired with the incorrect size of electrode and/or collet body.

Question 79

What electrodes are used for welding aluminum with AC current?

Answer 79

Cerium, Zirconia, Pure tungsten, EWG

Question 80

What are some characteristics of using Argon?

Answer 80

Smooth and quiet Easier to weld thin materials Greater cleaning on aluminum using AC Easier arc starting Lower flow rates Better resistance to drafts Heavier than air.

Question 81

Why is welding thin materials easier using argon?

Answer 81

Argon provides a stable arc and better control over heat input, reducing the risk of burning through the material.

Question 82

What type of joint protection is needed with stainless steels?

Answer 82

Full joint protection.

Question 83

How are the backsides of workpieces protected against atmospheric corrosion.

Answer 83

Purging or with the use of flux.

Question 84

What gases are used for purging?

Answer 84

Argon and nitrogen, due to their non-flammability.

Question 85

If no filler metal is added, the weld formed is called ___________ weld.

Answer 85

an autogenous