Questions and Answers
The chemical symbol for tungsten is?
W
How long should the post purge (shielding gas) be allowed to flow after the welding arc is broken?
Long enough to allow the base metal and electrode to cool.
When using GTAW to weld aluminum with alternating current (AC), the tip of the tungsten electrode should be?
rounded at the tip.
Alternating Current (AC) is used for welding aluminum because?
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Which of the following methods is used to start the GTAW arc without touching the base metal?
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High Frequency current is added to alternating current to?
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When the GTAW power source is set to DCEP, most of the heat is directed toward the?
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As a general rule, the inside diameter of the gas nozzle should be?
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Pulsed current is useful for welding stainless steel because it?
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Pulsed current is useful for welding out of position because?
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The shielding gas most commonly used for welding low carbon steel with GTAW is?
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To break up the oxide coating from aluminum prior to welding you should?
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Which of the following is not an advantage of GTAW?
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If tungsten spitting occurs, what may be done to correct the problem?
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An EWTh-2 electrode is?
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Tungsten is used for GTAW electrodes because it has which of the following properties?
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What approximate percentage of the heat of the arc is directed toward the electrode when welding with DCEP?
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The voltage present when the welding machine power switch is in the ON position, but no welding is taking place is called?
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Filler metal with an AWS classification of ER4043 is used to weld?
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Filler metal with an AWS classification of ER70S-X is used to weld?
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Filler metal with an AWS classification of ER308 is used to weld?
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Match the following terms with their definitions:
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GTAW is also commonly referred to as Tungsten Inert Gas and Heliarc Welding.
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GTAW is a good process for high-quality welds on a wide variety of metals.
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Shielding gas flow rates should be decreased when welding in the overhead position.
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GTAW produces no spatter and requires limited post-weld cleaning.
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It is not necessary to keep the hot end of the filler wire in the gas-shielding zone.
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The electrode classification EWP indicates a pure tungsten electrode.
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You must always use filler metal when welding with the GTAW process.
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Filler metal must be of the same composition as the base metal.
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Filler metals used for GTAW are similar in classification as those used for GMAW.
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Copper-coated mild steel filler metals used for oxyacetylene welding are also recommended for GTAW.
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Study Notes
GTAW (Gas Tungsten Arc Welding) Overview
- Tungsten's chemical symbol is W.
- Shielding gas should flow long enough to allow cooling of the base metal and electrode after arc termination.
- For aluminum welding using AC, the tungsten electrode tip must be rounded to ensure effective welding.
Current and Power Source Settings
- AC provides cleaning action and medium penetration, essential for aluminum welding.
- High frequency starts are used to initiate the GTAW arc without contacting the base metal.
- DCEP (Direct Current Electrode Positive) directs most heat (approximately 70%) toward the electrode.
Nozzle and Electrode Specifications
- Gas nozzle inside diameter should be three times the electrode diameter to ensure proper gas flow.
- Types of tungsten electrodes include:
- EWTh-2, which contains 2% thoriated tungsten.
- Ceriated (orange), 2% thoriated (red), pure (green), zirconiated (brown), and lanthanated (black) tungsten types are identified by colors.
Welding Techniques and Advantages
- Pulsed current reduces heat input, making it beneficial for welding stainless steel and for out-of-position welding due to better weld pool control.
- Argon is the most commonly used shielding gas for low carbon steel in GTAW.
- Effective oxide coating removal from aluminum requires using a stainless steel brush on the weld joint.
Filler Metal Classifications
- AWS classifications:
- ER4043 is for aluminum welding.
- ER70S-X is for carbon steel welding.
- ER308 is for stainless steel welding.
Common GTAW Myths and Facts
- GTAW is not known for a high deposition rate but is preferred for high-quality welds across various metals.
- Shielding gas flow rates must not be reduced when welding overhead, as sufficient gas coverage is essential.
- GTAW produces no spatter and requires limited post-weld cleaning, contributing to its cleanliness.
- Keeping the filler wire's hot end in the gas shield is necessary for effective protection against contamination.
Application and Process Validity
- Filler metal must match the base metal's composition for effective bonding.
- GTAW process can use filler metal, but it is not mandatory, unlike other welding processes.
- Filler metals for GTAW share similarities with those classified for GMAW (Gas Metal Arc Welding).
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Description
Explore the fundamentals of Gas Tungsten Arc Welding (GTAW), including the properties of tungsten, settings for current and power sources, and specifications for nozzles and electrodes. This quiz covers essential techniques and components vital for successful aluminum welding. Test your knowledge and understanding of these key concepts in GTAW.
