Gas Tungsten Arc Welding (GTAW), commonly known as Tungsten Inert Gas (TIG) welding, is a welding process that utilizes a non-consumable tungsten electrode to produce the weld. Here’s an overview of the GTAW process:
1. Equipment:
- Power Source: GTAW machines typically utilize a constant current (CC) power source, which provides stable control over the welding arc and heat input.
- Tungsten Electrode: GTAW electrodes are made of pure tungsten or tungsten alloys and are non-consumable, meaning they do not melt during the welding process. The electrode is held in a welding torch and connected to the power source.
- Shielding Gas: GTAW relies on a shielding gas, commonly argon or a mixture of argon and helium, to protect the weld from atmospheric contamination and stabilize the arc.
- Welding Torch: The welding torch holds the tungsten electrode and directs the flow of shielding gas to the weld area. It also contains a trigger mechanism for controlling arc initiation and gas flow.
2. Process:
- Preparation: Clean and prepare the workpieces to be welded, removing any rust, paint, or contaminants from the welding area.
- Tungsten Selection: Choose a tungsten electrode appropriate for the base metal, welding position, and desired weld characteristics. Thoriated, ceriated, or lanthanated tungsten electrodes are commonly used for various applications.
- Gas Selection: Select a shielding gas suitable for the base metal, welding position, and desired weld characteristics. Argon is the most commonly used shielding gas for GTAW welding.
- Electrode Setup: Grind the tungsten electrode to a sharp point or truncated cone shape and insert it into the welding torch. Adjust the electrode extension and gas flow rate based on the welding parameters.
- Arc Initiation: Position the welding torch at the desired starting point of the weld joint. Depress the torch trigger to initiate the arc, creating a stable and focused welding arc between the tungsten electrode and the workpiece.
- Welding Technique: Move the welding torch along the joint, maintaining a consistent travel speed and distance from the workpiece. Control the torch angle and direction to ensure proper weld penetration and bead shape.
- Deposition: As the welding arc heats the workpiece, a molten weld pool forms, which fuses with the base metal. The shielding gas protects the weld from atmospheric contamination and stabilizes the arc.
- Cooling and Inspection: Allow the welded joint to cool naturally, then inspect the weld for defects such as cracks, porosity, or incomplete fusion. Clean the weld area as needed.
3. Applications:
- GTAW is versatile and can be used to weld a wide range of metals and alloys, including stainless steel, aluminum, copper, titanium, and nickel alloys.
- It is commonly used in industries such as aerospace, automotive, marine, and precision manufacturing, where high-quality welds with precise control over heat input and weld appearance are required.
- GTAW is well-suited for welding thin to medium-thickness materials, as well as for producing welds with minimal spatter, distortion, and heat-affected zone.