TIG Welding (GTAW) Process
GTAW is an arc welding process in which the desired heat is obtained using an electric arc, between the workpiece and the tungsten electrode.
GTAW :An overview
Today, the popular welding process in the industry is “GTAW” welding. In this method, there is no risk of flux getting trapped due to not using any flux. Due to the clear visibility of the arc and the job, the welding operator can easily weld the joint.
TIG welding (GTAW or gas tungsten) is an arc welding process that works by heating metals to a high temperature (over 6,000 degrees Fahrenheit). Although it is more expensive than stick welding, it provides the best results with an attractive weld that is clean and strong. This process is more complicated than the others, so it requires good hand/eye coordination and practice.
Gas tungsten arc welding is an arc welding process in which fusion is produced by an electric arc striking between the electrode and the workpiece.
Welding in the GTAW process can be started in two ways, by touching tungsten on scrap metal or using a high-frequency unit. In the high-frequency method, bringing the torch from the job to two to three milliliters jumps a spark between the tungsten and the jab causing the air path to get ionized, and an arc is established.
Equipment used in GTAW Process
The flow meter with a welding torch, tungsten electrode, collet, and collet body, filler metal, power source, high-frequency unit, cables, inert gas, pressure regulator for inert gas, and water supply and valves for water and gas solenoids is needed.
Both DC and AC welding machines with good current control can be used for the GTAW welding process.
DC is preferred for welding stainless steel, nickel, copper, and copper alloys whereas DCRP or AC is used for welding magnesium, aluminum, and their alloys. Reverse polarity of current removes oxide film on aluminum and magnesium.
How it Works
When using AC, a high-frequency unit is employed to keep the arc ignited and stabilized.
A DC suppressor unit is incorporated in the electrical circuit to balance the current wave.
A DC, suppressor unit reduces the effect of DC component of current which comes into operation due to the fact that arc voltage is more when the electrode is positive than when it is negative.
In the absence of a DC suppressor unit, the arc may blow and behave erratically, and the transformer may become saturated, over-heated and derated.
Various types of inert gases are used in the GTAW welding process:
- A mixture of Argon and helium
- A mixture of Argon and Hydrogen
- A mixture of Argon and oxygen
Joint Design for GTAW
Usually, Butt, Lap, Corner, Edge, and T joints are welded by using the GTAW process,
GTAW can be applied for welding:
Carbon and alloy steels, Stainless steels, Refractory metals, Copper alloys, Aluminium alloys, Magnesium alloys, Nickel alloys, heat-resisting alloys, etc
Advantages and Disadvantages
- This is a good welding process for non-ferrous metal.
- Flux is not used in this welding process, so there is no risk of flux impingement.
- In this method, the welding job is clearly visible because of its clear visibility, so that welding can be well performed.
- This method is very good for thin metals and high-quality welding can be achieved.
Despite such qualities, there are some disadvantages to this process, such as: –
- If the filler wire comes out of the shielding zone, there is a risk of contamination of the weld metal.
- Compared to other welding processes, the cast of this process is higher.
- If tungsten is transferred to molten metal, there is a risk of defect”tungsten inclusions”.
In today’s era, gravitation and compaction are the most common welding processes in the arc welding process, they are used in the welding of the industry as well as general equipment, mainly due to their portability and ease of use.