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W.I-W2 > GTAW Electrodes, Filler Metals and Shielding > Flashcards

GTAW Electrodes, Filler Metals and Shielding Flashcards

1
Q
  1. A characteristic of tungsten is that it:
    a) oxidizes readily.
    b) dissolves homogeneously into the weld.
    c) retains its hardness at red heat.
    d) has a melting point of 325ºC (617ºF).
A

c) retains its hardness at red heat.

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2
Q
  1. Tungsten is classed as a __refractory___ metal, which means that it has a high
    melting point of _____(6170°F).________.
A
  1. Tungsten is classed as a __refractory___ metal, which means that it has a high
    melting point of _____(6170°F).________.
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3
Q
  1. What type of electrode is used for the gas tungsten arc welding process?
    a) consumable
    b) non-consumable
    c) flux coated
    d) flux cored
A

b) non-consumable

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4
Q
  1. The advantage that a ground-finished electrode has over a chemically cleaned
    electrode is that it:
    a) has better electrical contact with the collet.
    b) is easier to strike the arc.
    c) produces more heat in the torch body.
    d) gives you better control with out of position work.
A

a) has better electrical contact with the collet.

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5
Q

The reason thoria is added to GTAW electrodes is to:
a) increase electrical resistance at the molten end.
b) improve the electrode’s ability to create a clean, round, balled end.
c) improve thermal conductivity which promotes cooling.
d) increase current-carrying capacity and arc stability.

A

d) increase current-carrying capacity and arc stability.

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6
Q
  1. An EWTh-1 electrode would be a good choice for welding:
    a) aluminum.
    b) magnesium.
    c) cast iron.
    d) mild steel.
A

d) mild steel.

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7
Q
  1. What would be a good current choice for a green-coded electrode?
    a) DC reverse polarity on mild steel
    b) AC with start only high frequency on stainless steel
    c) DC straight polarity on magnesium
    d) AC with continuous high frequency on aluminum
A

d) AC with continuous high frequency on aluminum

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8
Q
  1. State three (3) methods that may be used to prepare an electrode for welding.
    a)
    b)
    c)
A

a) electrical arc
b) grinding
c) chemical sharpening

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9
Q
  1. An EWTh-2 ground to a conical point is prepared correctly for welding on:
    a) stainless steel.
    b) aluminum.
    c) magnesium.
    d) aluminum/magnesium castings.
A

a) stainless steel.

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10
Q
  1. What protects the electrode from atmospheric contamination?
    a) shielding gases
    b) fluxes
    c) electrode coatings
    d) water cooling of the torch
A

a) shielding gases

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11
Q
  1. Oxidation of the electrode immediately after the arc is extinguished is prevented by:
    a) a post-flow of the shielding gas.
    b) working within the recommended current ranges.
    c) selecting the correct grade of tungsten electrode.
    d) not touching the electrode to the work.
A

a) a post-flow of the shielding gas.

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12
Q
  1. How can the electrode in Figure 22 be prepared to a clean, balled end without the use of a grinder or chemical compound?(image)
A

Break the contaminated end off using a clamping tool to prevent the electrode from splitting. Set to a much higher current on AC or use DCEP. Strike an arc and hold until the end ball is formed. Adjust the power source and continue welding

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13
Q
  1. What is the primary consideration when selecting a filler rod?
A

The primary consideration is the type of material so as to ensure the rod chemistry and mechanical properties match the required job specifications.

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14
Q
  1. Which two filler metals can be used to weld most weldable aluminum alloys?
    a) ER1100 and ER3003
    b) ER4043 and ER5356
    c) ER5083 and ER5454
    d) ER6061 and ER6351
A

b) ER4043 and ER5356

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15
Q
  1. The AWS/CSA filler metal classifications for GTAW of carbon steels may also be used for:
    a) SMAW.
    b) FCAW.
    c) SAW.
    d) GMAW.
A

d) GMAW.

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16
Q
  1. Interpret the following filler metal classifications.
    a) B-G 49A 3 A G2
    B =
    G =
    49A =
    3 =
    A =
    G2 =
    b) ER347
    E =
    R =
    347 =
    c) ER4043
    E =
    R =
    4 =
    0 =
    43 =
A

a) B-G 49A 3 A G2
B = electrode was classified by tensile strength and tested with an average 27 joule impact test.
G = gas shielded metal arc welding process
49A = the minimum tensile strength of the deposited weld metal
in the as-welded condition in megapascals (MPa) divided by 10
3 = a minimum of -30°C temperature for impact tests
A = argon as a shielding gas
G2 = the manufactured chemical analysis
b) ER347
E = electrode
R = rod
347 = grade of stainless steel
c) ER4043
E = electrode
R = rod
4 = major alloying element
0 = modification to the alloy
43 = identifies the specific alloy within the group

17
Q
  1. To prevent porosity during GTAW of rimmed steels, filler rods must have:
    a) multiple deoxidizers.
    b) a high manganese content.
    c) a low carbon content.
    d) a low silicon content.
A

a) multiple deoxidizers.

18
Q
  1. CSA filler metal specifications differ from AWS specifications in that tensile strength
    is expressed in:
    a) kilograms.
    b) joules.
    c) newtons.
    d) megapascals.
A

d) megapascals.

19
Q
  1. Which of the following aluminum filler rods has magnesium as its major alloying element?
    a) ER1100
    b) ER2319
    c) ER4043
    d) ER5356
A

d) ER5356

20
Q
  1. GTAW filler rods should be properly stored to prevent contamination from:
    a) moisture.
    b) ozone.
    c) non-ionizing radiation.
    d) high frequency current.
A

a) moisture.

21
Q
  1. What are two (2) advantages of using consumable inserts for the joining of pipe?
A

Any two (2) of the following are correct.
a) consistent quality of metal deposit
b) suitable when access is only from one side
c) exact metallurgical properties are obtainable
d) smooth, crevice-free internal weld surfaces
e) can serve as backing rings

22
Q
  1. What is the maximum allowable gap when joining the ends of a consumable insert?
A

(1/32”)

23
Q

24.Name two (2) shielding gases used with GTAW that are described as:
a) inert =
b) reactive =

A

a) inert = argon and helium
b) reactive = nitrogen and hydrogen

24
Q
  1. Explain why argon-CO2 gas mixtures are not recommended for GTAW.
A

-CO2 breaks down in the heat of the arc

  • turns into carbon monoxide and oxygen

-Causing electrode oxidation and weld metal contamination

25
Q
  1. The gas shielding of the GTAW process:
    a) promotes the flow of filler metal to the bead edges.
    b) allows arc ignition without having to touch the electrode to the work.
    c) protects the electrode and the weld puddle from atmospheric contamination.
    d) helps to control AC arc rectification.
A

c) protects the electrode and the weld puddle from atmospheric contamination.

26
Q
  1. Which of the following gases is the heaviest in air?
    a) argon
    b) helium
    c) nitrogen
    d) hydrogen
A

a) argon

27
Q
  1. Which of the following is a characteristic of argon shielding gas?
    a) promotes deep penetrating qualities
    b) used for fast welding speeds
    c) narrow heat-affected zone
    d) smooth quiet arc action
A

d) smooth quiet arc action

28
Q
  1. Which gas generally requires higher flow rates? Why?
A

Helium because it is lighter than the atmosphere and tends to disperse from the weld zone quickly

29
Q
  1. When using GTAW on aluminum, changing from argon to a mixture of argon-helium results in:
    a) improved cleaning action.
    b) a much faster welding speed.
    c) a reduced risk of hot short cracking.
    d) a flatter weld bead.
A

b) a much faster welding speed.

30
Q
  1. The shielding gas mixture argon-hydrogen is an advantage when welding:
    a) heavy mild steel materials.
    b) at high speeds on aluminum.
    c) root passes on copper pipe.
    d) light wall stainless steel with automatic equipment.
A

d) light wall stainless steel with automatic equipment.

31
Q
  1. The gas best suited for manual GTAW on carbon steels is __.
A
  1. The gas best suited for manual GTAW on carbon steels is argon.
32
Q
  1. When using GTAW on aluminum, what inert gas produces the most efficient oxide
    removal?
    a) argon
    b) helium
    c) neon
    d) xenon
A

a) argon

33
Q
  1. Helium is used as a shielding gas on stainless steel when:
    a) high heat input is of primary importance.
    b) undercutting at the edges is a problem.
    c) maximum penetration is desired.
    d) root bead contamination becomes excessive
A

c) maximum penetration is desired.

34
Q

Electrode-Alloying Element-Colour Code
EWP -None- Green
EWTh-1 -Thoria- Yellow
EWTh-2 -Thoria -Red
EWLa-1 -Lanthana -Black
EWCe-2 -Ceria -Orange
EWZr -Zirconia- Brown
EWG -Unspecified oxide or element-
Grey

A

Electrode-Alloying Element-Colour Code
EWP -None- Green
EWTh-1 -Thoria- Yellow
EWTh-2 -Thoria -Red
EWLa-1 -Lanthana -Black
EWCe-2 -Ceria -Orange
EWZr -Zirconia- Brown
EWG -Unspecified oxide or element-
Grey

W.I-W2 (4 decks)

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