Gas Tungsten Arc Welding

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Gas Tungsten Arc Welding
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Gas Tungsten Arc Welding
Heat is produced by an electric arc between a non
consumable tungsten electrode and the work.
Why Tungsten High Tensile Strength 500,000lbs/in
² 75,000lbs/in² Hardness C45
Rockwell Mild Steel C20 High Melting
6170 High Boiling Temperature 10,700
F Good Electrical Conductivity
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Gas Tungsten Arc Welding

• Does not melt but erodes due to heat
• Good collet to electrode contact
• Low current
• Water-cooled torch
• Large tungsten
• DCEN
• Keep electrode short

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Types

• Pure Green Aluminum Magnesium
• Thorium Improves Current Capacity
• 1 yellow, 2 Red mild steel, stainless steel
• Zirconium ¼ to ½ Brown
• AC Aluminum Improved weld pool
• Cerium 2 Orange, AC or DC Not radio active
• Lithium 1 Not radio active

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Tungsten Shape
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Sharpening Tungsten

• Grind with lines going from the point to the
  downward.
• Should be on a separate wheel for tungsten only?

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AC Oxide Removal
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High Frequency
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Shielding Gases

• Base
• Argon
• Heavier than Air
• Not for overhead
• Cheap

• Additives
• Helium
• Deeper penetration
• Better cleaning
• 75 Helium 25 Argon
• Hydrogen
• Adds penetration
• Nitrogen
• Adds penetration

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Gas Flow

• Pre Purge
• Gas flow prior to start of an arc. Clears Oxygen
  from the area

• Post Purge
• Gas flow after the arc has stopped. Keeps oxygen
  from the area until area solidifies.

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Gas Tungsten Arc Welding Parts of a welder
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Parts of a torch