Terms Commonly Used in Gas Shielded Welding Process

Shielding gases are inert or semi-inert gases that are commonly used in several welding processes, most notably gas metal arc welding and gas tungsten arc welding (GMAW and GTAW, more popularly known as MIG (Metal Inert Gas) and TIG (Tungsten Inert Gas), respectively). Their purpose is to protect the weld area from oxygen, and water vapour. Depending on the materials being welded, these atmospheric gases can reduce the quality of the weld or make the welding more difficult. Other arc welding processes use alternative methods of protecting the weld from the atmosphere as well – shielded metal arc welding, for example, uses an electrode covered in a flux that produces carbon dioxide when consumed, a semi-inert gas that is an acceptable shielding gas for welding steel.

Welding involves a lot of terms that can be confusing for beginners. Check out these frequently asked questions about common welding terms so you understand the difference between duty cycle and direct current.

Arc Length:

Distance Between the tip of the electrode and the Surface of the Weld Pool is Know as Arc Length.
Base Metal:
Incorrectly used to describe the metal from which the components of the joint are made. The correct term is Parent Metal.
A single run of weld metal deposited onto the surface of the Parent metal is know as Bead.
Deposited Metal:
The material which is added, either from the electrode or filler wire, to build up the weld profile is know as Deposited Metal.
Deposition Rate:
The rate at which melted electrode metal is added to the weld pool. Quoted in kg/hr (Kilograms per hour). Sometimes incorrectly used in reference to the ratio of electrode melted this is the deposition effeciency.
The flux coated rod in manual metal arc welding, the tungsten in TIG and plasma welding and the consumable wire in MIG or MAG welding. The arc is formed between the parent metal and one end o the electrode.
Filler Metal:
Metal added to the weld pool during welding is know as Filler Metal. For TIG it is supplied as cut lengths of wire.
Inter pass Temperature:
The temperature of the material adjacent to the joint between each run is the inter pass temperature. In some applications, a maximum temperature is specified to avoid metallurgical changes in the metal.
Melt Run:
Melting the Parent metal by passing a TIG arc along the surface. Filler metal is not used.
In TIG and MIG or MAG welding. A metal or ceramic tune which confines the shielding gas to the weld area.
Parent Metal:
The metal which is to be joined by welding process is know as Parent Metal. Often incorrectly called the base metal.
Pass or Run:
The metal deposited during one traverse of the joint by an arc. In TIG welding without a filler, the term melt run may be more correct.
Preheat Temperature:
The temperature of the Parent Metal just before welding is started is know as Preheat Temperature. With some metals the Parent Metal is heated before welding to avoid problems such as cracking or lack of fusion.
Root Run:
The first run deposited in a join where further runs are needed to fill the groove is called Root Run.
Sealing Run:
A run of weld metal deposited on the reverse side of a butt joint, along the line of the root.

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