AWS SENSE Level I
Module 7: GTAW
1. Copper-coated mild steel filler metals used for oxyacetylene welding are NOT
recommended for GTAW.
2. Filler metals used for GTAW are similar in classification as those used for GMAW.
3. Filler metal must be of the same composition as the base metal.
4. You do not always use filler metal when welding with the GTAW process.
5. The electrode classification EWP indicates a pure tungsten electrode.
6. It is necessary to keep the hot end of the filler wire in the gas-shielding zone.
7. GTAW produces no spatter and requires limited post-weld cleaning.
8. Shielding gas flow rates should be Increased when welding in the overhead
position.
9. GTAW is a good process for high quality welds on a wide variety of metals.
10. GTAW is also commonly referred to as Tungsten Inert Gas and Heliarc Welding.
11. Ceriated Tungsten
12. 2% Thoriated Tungsten
13. Pure Tungsten
14. Zirconiated Tungsten
15. Lanthanated Tungsten
Tungsten classification colors
Orange
Red
Green
Brown
Black
Power supplies
16. Magnesium
17. Mild steel
18. Aluminum
19. Stainless Steel
AC
DCEN
AC
DCEN
20. Direction of welding
A
21. Collet body
22. Torch
23. Tungsten electrode
24. Gas Shield
25. Arc
26. Solidified weld metal
27. Filler metal
28. Gas nozzle
D
B
E
AC
AD
AE
AB
C
29. Filler metal with an AWS classification of ER308 is used to weld Stainless steel.
30. Filler metal with an AWS classification of ER70S-X is used to weld Carbon steel.
31. Filler metal with an AWS classification of ER4043 is used to weld Aluminum.
32. The voltage present when the welding machine power switch is in the ON position,
but no welding is taking place is called Open-Circuit voltage.
33. The approximate percentage of the heat of the arc directed toward the electrode
when welding with DCEP is 70%.
34. Tungsten is used for GTAW electrodes because it has which of the following
properties? High melting point, Low electrical resistance and Good heat conductivity
35. An EWTh-2 electrode is
2% Thoriated tungsten.
36.
If tungsten spitting occurs, what may be done to correct the problem?
Change to a different type of tungsten electrode.
Use a larger diameter tungsten electrode.
Decrease the welding current.
37. High deposition rate is not an advantage of GTAW?
38. To break up the oxide coating from aluminum prior to welding you should brush the
weld joint with a stainless steel brush.
39. The shielding gas most commonly used for welding low carbon steel with GTAW is
ARGON.
40. Pulsed current is useful for welding out of position because the weld pool is easier to
control.
41. Pulsed current is useful for welding stainless steel because it produces less heat
input than steady current.
42. As a general rule, the inside diameter of the gas nozzle should be three times the
electrode diameter.
43. When the GTAW power source is set to DCEP most of the heat is directed toward the
electrode.
44. High Frequency current is added to alternating current to maintain the arc.
45. High frequency start method is used to start the GTAW arc without touching the
base metal .
46. Alternating Current (AC) is used for welding aluminum because of the cleaning action
and medium penetration of the arc.
47. When using GTAW to weld Aluminum with alternating current (AC), the tip of the
tungsten electrode should be rounded at the tip.
48. The post purge (shielding gas) should be allowed to flow after the welding
arc is broken Long enough to allow the base metal and electrode to cool.
49. The chemical symbol for tungsten is W