The gas tungsten arc welding (GTAW) is also known as TIG welding (Tungsten inert gas). The consumable tungsten electrode is produced the arc to generate the required heat. It is similar to form of arc welding process. In this method the arc generated between the base metal and tungsten electrode. When the electrode is used to only create the arc and it is non-consumed in welding process. The welding gun provided inside of electrode holder. It gun made of ceramics or it is cooled by using water.
The weld zone, electrode and arc are surrounded by an inert gas. Thus gas usually as helium, argon or both are mixed. The argon is mostly used in welding process because of it is heavier and produce better shielded low flow rating.
The welding gun hold the electrode, carries inert gas and electric current. When the electric power is supplied by electric transformer through hoses. In this gas flow rate controlled by the value fitted on the cylinder. Strikes the arc by maintain the air gap between electrode and work piece, the gas inserted from the gun for the value in the torch.
Now the welding area displaces the shielding gas to atmospheric air and the contamination of weld metal with hydrogen and oxygen in the air. If the filler wire are provided between the molten materials. For high speed welding process the automatic filler wire feed with rated speed into the arc is used. The filler wire is similarly in composition to welded material.
In this gas tungsten arc welding process the AC power is used for best of non-ferrous material. The DC power source is suitable for ferrous alloys in straight polarities. The straight polarities will be reducing the loss of tungsten electrode.
The electrodes are alloyed with thorium (around 1%) or zirconium. For alternating current application, Zr alloyed tungsten is used. Pure Ti electrode are suitable for AC welding of aluminum and magnesium.
The arc welding from voltage may be range from 10v to 15v with current for 50-350 amps in argon material and voltage of 15-25 v with current of 50-350 amps in helium shielding gas. It TIG welding is suitable for 7 mm metal thickness and below.
Advantages of gas tungsten arc welding:
Some advantages of gas tungsten arc welding:
- All position of metal will be welded
- The weld is equal to base metal in composition
- The finished weld surfaces not require cleaning process because of flux is not used.
- Smoke or fumes not presented to obscure vision
- The heat is concentrated in the small area, so distortion of base metal is minimal
- The metal is not transferred across the arc, so no splatter is provided.
- Thus produce high quality weld on non-ferrous metal.
Application of gas tungsten arc welding:
It is general to common welding process of aluminum. The gas tungsten arc welding used to weld for following materials.
- Copper base alloys
- Nickel base alloys
- Low alloy steel
- Dissimilar metal like as copper
- Titanium and its alloy
- Hard falling
- Magnesium alloy
It is suitable for thin sheet 0.5 to 3 mm thickness produce weld with excellent quality and surface finish.
It is used for pressure vessels, pipes, and heat exchanger where tight less is important.