GTAW Welding (TIG) Overview

GTAW Welding process is also commonly known as TIG welding or Tungsten Inert Gas welding. It is an arc welding process that uses a non-consumable electrode (tungsten) for producing welds. Normally, the TIG type uses filler materials but in some cases, it may not be required. In this process, the weld area is protected by atmospheric contamination of inert shielding gas.

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Post Highlights:

• What is TIG Welding?
• TIG Welding Equipment
• Shielding Gases for Different Metals in TIG Welding
• Gases Emitted from Welding Processes
• How to Protect from Welding Gases?
• Where the TIG Welding is Used?
• Employment Areas for TIG Welding
• Companies Hire TIG Welders
• Job Types for TIG welders
• Salary of TIG Welder

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What is TIG Welding?

GTAW (TIG) welding is one of the welding techniques. It happens by striking an arc between the workpiece and a non-consumable tungsten electrode. An inert gas, usually argon protects the weld pool and the electrode which is supplied through a gas cup at the end of the welding gun.

TIG Welding Equipment

Same to other welding types, gas tungsten arc welding (GTAW) also use the equipment for the process. They are as follows:

1. Welding Gun

The welding gun must be well insulated and easy to handle for manual welding activities. Mechanical welding requires these necessary things. Mainly, there are two types of welding guns.

i) Water-cooled Welding Gun: It can carry welding currents of 400 A.
ii) Air-cooled Welding Gun: It can carry welding currents of 200 A.

2. Igniting the Arc

A high-frequency generator is mainly the source of ignition. It produces a spark that initials a necessary conducting path. The frequency of the initial ignition pulse can be different MHz.

Normally, welders should not practice striking the arc by scraping the electrode on the workpiece. Because it causes a risk of tungsten inclusions in the weld and damage to the electrode. Instead, another method is the ‘lift-arc’ method which happens by touching the electrode against the workpiece.

3. Source of Power

Normally TIG works on using DC with the electrode connected to the negative. When the electrode is connected to the positive pole, the oxide layer is broken down when welding aluminum. Therefore, the magnesium and aluminum are normally welded with AC. Generally, TIG power sources are controlled electronically.

4. Square Wave AC

During the 1970s, several new designs of power sources were being applied. Basically, they work on a new technology involving a square waveform. They do not use a continuous HF ignition voltage for AC TIG welding.

5. Pulsing of Thermal

Pulsing of thermal mainly provides better control of the melt pool and the solidification process. The setting of pulse frequency low allows the melt pool to partially solidify. Supplying the heat in pulses has some advantages such as better control of penetration and the penetration profile; better control of the weld pool in positional welding; less sensitivity to gap width variations; and reduced sensitivity to uneven heat conduction and removal.

6. Equipment for Control

The requirement of control equipment depends on the extent of the welding process mechanization. It is usual to be automatically controlled for the pre-flow and post-flow of the shielding gas, and the HF generator. The slope-down of the current and the ability to pulse the current fill the craters. The gas pre-flow and post-flow protect the electrode and weld pool against oxidation.

7. Electrodes for TIG Process

There are many noteworthy features before selecting a suitable electrode for TIG welding. Welders should consider them.

• Good emission of electrons
• High melting point
• Good thermal conductivity
• Low electrical resistance
• The material that best meets these requirements is tungsten

Take a look at IS0 6848 TIG welding electrodes and their details

Additive	Proportion (%)	Color Codes	Types	AC/DC
	0	Green	WP	AC
Cerium	2	Grey	WC20	AC/DC
Lanthanum	1	Black	WL10	AC/DC
Zirconium	0.8	Brown	WZ8	AC
Thorium	2	Red	WT20	DC

Shielding Gases for Different Metals in GTAW Welding

There are many gases used in welding processes and other related welding cutting processes. They are fuel gases (Acetylene, Propane, Butane) and shielding gases (Carbon Dioxide, Argon, Helium). Besides this, a small amount of oxygen is used in both fuel gas and shielding gas as a mixture.

The shielding gases are used according to the materials of the workpiece while performing the TIG welding process.

1. Shielding Gas for Steel

Generally, TIG welding employs Argon for the following materials such as stainless steel, unalloyed steels, and low-alloyed steels. The mixture of Hydrogen or Helium and Argon as a shielding gas is applied to the mechanical welding of all these metals. When welding duplex stainless steel, a small addition of nitrogen may be used to ensure the correct ferritic austenitic balance. The root gas is used while making quality welds with TIG welding to protect the root site of the weld against oxidation. The root gas is a mixture of nitrogen, hydrogen, or pure argon.

2. Shielding Gas for Aluminum and its Alloys

While performing TIG welding for aluminum and aluminum alloys, the shielding gas is usually argon, and sometimes mixed with helium. The Helium is mainly added to improve the heat transfer or when to weld thicker sections. Normally, the welding current is AC or at low current levels. It may be DC with the electrode connected to the positive. Employing argon as a shielding gas improves things like oxide breakdown performance, arc stability, and weld quality.

3. Shielding Gas for Copper and its Alloys

Argon is considered a suitable option for welding copper in all positions. Besides this, it imparts excellent results when welding metal thicknesses up to about 6 mm. In this case, preheating is required for the high thermal conductivity of the metal. The best shielding gas for welding workpieces more than 6 rnm thick is helium, or helium containing 35% argon.

4. Shielding Gas for Titanium

The selection of shielding gas for titanium welding requires extremely high purity not less than 99.99 %. But in some cases, an extra shielding gas is required. Possibly, it may be either helium or argon. Generally, argon is suitable for metal thicknesses up to about 3 mm due to its good shielding performance and higher density.

Gases Emitted from Welding Processes

All the burning things produce some amount of gases and fumes. Welding and cutting processes also emit gases. Take a look.

Sr. No.	Gas Types	Activity/Processes
1.	Carbon Dioxide (CO2)	Emitted by the breakdown of CO2 Shielding gas
2.	Nitrogen Oxide (NO)	Produced due to the heating of nitrogen and oxygen from the atmosphere
3.	Carbon Monoxide (CO)	Produced due to the decomposition of fluxes
4.	Hydrogen Chloride (HCl) and Phosgene (COCl2)	Created due to the reaction of vapors and ultraviolet lights.
5.	Ozone (O3)	Emitted due to the interaction of atmospheric oxygen and an electric arc.

How to Protect from Welding Gases?

The fumes and gases emitted from welding are harmful to human beings. Every welder should read safety instructions from the manufacturer before starting welding. Some of the general safety measures are listed below:

i) There should be a proper ventilation system for removing gases and fumes from the nearby breathing zone.
ii) Always wear appropriate respiratory protective equipment, possibly made up of the latest technologies.
iii) Welders should not use the fan for blowing fumes away; it can be a problem for everyone working around.
iv) Welders should not weld places still wet using degreasing solvent.
v) There should be enough availability of oxygen at the welding spot for breathing easily.

Applications of GTAW Welding

Where the TIG welding is used?

Different industries use TIG welding in the stainless-steel sections and non-ferrous metals such as aluminum, magnesium, and copper alloys. It can be used on steel, brass, bronze, copper, nickel, aluminum, magnesium, and gold. TIG welding is clean as it does not create smoke and fume.

In addition, TIG welding is used for applications such as joining pipes and welding tubes into the end plates of heat exchangers. The main of TIG welding is for stainless steel welding, welding of light metals i.e. aluminum and magnesium alloys, and copper welding. The following industries use GTAW welding on large scales.

1. Use of TIG in the Automotive Industry – The car industry mainly uses TIG welding for its secure construction. Further, TIG welding reduces corrosion and protects cars from rust over time due to its advanced techniques.

2. Use of TIG in Pipe Industry – The use of TIG welding in the piping industry is for joining pipes at various angles, for example, in the chemical industry, the Bicycle industry, etc.

3. Use of TIG in the Aerospace Industry – TIG welding made space journey easy by constructing safe aircraft and spacecraft. There is wide use of TIG type in commercial aircraft manufacturing companies like Boeing Company. Due to its strength and precision, it is used for making special complex crafts like International Space Station (ISS).

4. Use of TIG in the Art/Sculpture Industry – Normally, TIG welding is known for its superior cosmetic appearance. It may be used in the metal sculpture industry and other similar metal works of art.

5. Use of TIG in Repair Industry – GTAW is used in the repair industry extensively ranging from small toys to heavy airplanes. GTAW welding is handy and can be performed even on tiny child-playing wagons, and tools made up of aluminum.

6. Use of TIG in Military/Defense Industry – When you think about the defense industry accuracy matters the most. But due to TIG welding’s modern techniques and tools, welders achieve that much level of required accuracy.

Tungsten inert gas welding is suitable for all weldable materials with all types of joints and in all welding positions, except lead and zinc. It is best suited to thin materials of 0.5 rnm up to about 3 rnm thick.

Employment Areas for GTAW Welding

The following are the main areas for TIG welding activities.

• Automobile Industry
• Defense Industry
• Pipe Industry
• Repair Industry
• Sculpture/Art Industry
• Space Industry
• Welding Schools & Colleges

Companies Hire TIG Welders

There are so many welding companies and institutions that recruit welders for various positions. Some of them are as follows.

• AMC Fabrication, Las Vegas, NV
• MDC Vacuum, Hayward, CA
• Robert’s Company, Roanoke Rapids, NC
• SpaceX, Hawthorne, CA

Job Types for TIG Welding

The following are job types for TIG Welding.

• Educator/Instructor
• TIG Operator
• TIG Pipe Welder
• TIG Welder
• TIG Welder/Fabricator
• TIG/GTAW IV Chamber Welder

Salary of TIG Welder

All the welders do not fetch the same monthly or yearly salary in the entire United States. There are many factors that affect salary trends in the welding industry. The dominant factors are the number of welding industries, location, experiences, skills of a welder, rampant competition, etc. Generally, a TIG Welder is given $18.36 per hour.

Conclusion

Above all, almost every industry uses GTAW welding in different welding activities. The information on TIG welding types is beneficial for students, welders, educators, and welding professionals in many ways.

Related: Other Welding Types