Development of GTAW

In 1942 Russell Meredith received a patent for a welding torch that utilized inert gas . This was in association with Northrop Aircraft Inc. The challenge at hand was to produce a welding process for Magnesium and other nonferrous materials that bring specific challenges. Magnesium was already being used in aircraft to reduce weight but was limited to extruded and riveted parts because Magnesium burns at temperatures above 883 degrees Fahrenheit. This makes other welding processes unsuitable. The answer to this predicament was to blanket the electric arc and molten weld pool with inert gas. You can see the original sketch of the welding torch.

Since then, there have been many advances in GTAW, from the alloying elements in the tungsten, water-cooled touches, power sources using different polarities, customizing the AC wave, and even automation. Let’s look more closely at these.

Basics of the process

The GTAW process involves an intense arc between the base metal and a tungsten electrode to create a molten puddle. The intensity of this arc is controlled by a foot pedal or a hand-held device that can vary your amperage/current. After establishing a molten puddle, filler material is added, though there are applications where no filler material is added; this is an autogenous weld. The arc, electrode, and weld zone are surrounded by an inert gas (usually argon, helium, or a mixture of the two) that displaces the air and eliminates the possibility of weld contamination by the oxygen and nitrogen present in the atmosphere. The tungsten electrode has a high melting point that makes it virtually non-consumable. This does not make it indestructible. Tiny bits of tungsten can spit into your weld and create inclusions.

Advantages of gas tungsten-arc welding (GTAW) include the following:

• Welding can be done in all positions.
• The weld is usually equal to the base metal in composition.
• Flux is not used; therefore, finished welds do not require cleaning of corrosive residue.
• Smoke or fumes are not present to obscure vision; therefore, you can easily see the welding process.
• The process gives you a high level of control of the weld puddle.
• No spatter is produced because metal is not transferred across the arc.

Disadvantages of GTAW include the following:

• Material needs to be extremely clean, and material preparation takes more time.
• Portability is reduced because of the need for shielding gas.
• Welding outdoors requires extra caution; wind 5 mph or more will disrupt your shielding gas, leading to contamination and porosity.
• Slower welding process and may lead to excessive heat input.

Uses of GTAW in Industry Today

Some of the industries that utilize GTAW are:

• Food processing equipment (for extremely clean stainless steel welding)
• Casting repair (Wide range of materials that will need miner repair)
• Aerospace/Spacecraft (ability to weld exotic materials like Titanium and inconel)
• Boilers and refineries (for welding boiler tube in tight spaces)

Attributions

1. Figure 11.2: Welding Torch by Russel Meredith in the Public Domain; U.S. Patent: Subject to limited exceptions reflected in 37 CFR 1.71(d) & (e) and 1.84(s), the text and drawings of a patent are typically not subject to copyright restrictions (https://www.uspto.gov/terms-use-uspto-websites).
2. Figure 11.3: GTAW by Duk is released under CC BY-SA 3.0