11.5 Chapter Conclusion

Karl Fulton

Summary

GTAW is an arc welding process utilizing a non-consumable tungsten electrode and inert gas to protect molten puddles. Originally developed for welding magnesium it is now utilized for a wide variety of metals. GTAW gives you a very high degree of control over the molten puddle. You will see this process used widely in many industries such as food processing equipment, casting repair, aerospace, spacecraft, and more.

The weld machine can have a wide variety of settings to help with puddle manipulation, arc shape and even cleaning. Use direct current straight polarity for most welding and alternating current for aluminum and magnesium.

The type of gas or mix of gas you use will affect the penetration of your weld. Argon (heavier than air) is the most common. Helium (lighter than air) will create a hotter puddle and can be mixed with argon for a desired effect.

The type of tungsten you use can be a personal preference as there are many alloys of tungsten. Pure Tungsten is for AC welding with a transformer-type welding machine.

Cleanliness and fit-up are incredibly important and should not be taken lightly.

This chapter is simply the tip of the iceberg when it comes to GTAW. If you are a hobbyist or plan to make a career of GTAW I hope this has helped you on your path.

Review Questions

  1. What was GTAW originally developed for?
    1. Welding magnesium.
  2. What do you do if it starts to hurt as you are welding?
    1. Stop
    2. Suck it up
    3. Grit my teeth
    4. Make funny noises until I am done.
  3. What is the concern about using a thoriated tungsten?
    1. Radioactive dust from grinding
  4. What percentage if heat is on the tungsten when welding in Straight polarity(DCEN)
    1. 30%
    2. 70%
    3. 50%
    4. None of the above
  5. What is the approximate melting temperature of pure aluminum?
    1. 1200 degrees
    2. 3700 degrees
    3. 1300 degrees
    4. 5500 degrees
  6. What is the approximate melting temperature of aluminum oxide?
    1. 3700 degrees
    2. 1200 degrees
    3. 1330 degrees
    4. 5500 degrees
  7. What is one of the advantages of using a gas lens over a colet body?
    1. Greater tungsten stick out
    2. Better gas coverage
    3. Less gas consumption
    4. All of the above
  8. What is an Autogenous Weld
    1. Weld using only the base material
    2. Weld that is made for the auto industry
    3. Weld is made automatic
    4. All of the above
  9. Why is it important to fill the crater when welding aluminum?
    1. Cracks will develop in the crater if not filled.
  10. When GTAW what should melt the filler rod?
    1. The arc
    2. The puddle

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Introduction to Welding Copyright © by Washington State Board for Community and Technical Colleges is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.