Fusion welding: types and mechanism of arc welding

Types of arc welding

Arc welding is a type of fusion welding and is widely used in various industrial fields.
There are many varieties of arc welding that are selected depending on the material characteristics, mechanism of the equipment, and gas to be used. Gas shielded arc welding that uses a shielding gas to protect the weld from atmosphere, such as TIG welding, MIG welding, and MAG welding, has been used extensively due to ease of automation.

Arc welding, including gas shielded arc welding, is broadly divided into two types: consumable (fusible) electrode type and non-consumable (non-fusible) electrode type depending on whether the welding rod/wire melts in the process or not.

Arc welding
Electrode consumption Welding method
Non-consumable (non-fusible) electrode type
  • TIG welding
  • Plasma welding
Consumable (fusible) electrode type
  • Shielded metal arc welding
  • MAG welding
  • MIG welding
  • Electrogas arc welding (EGW)

The classifications above are just an example. There are various ways to classify the types, and some may differ from the table above.

Mechanism of arc welding

Arc welding uses an electric phenomenon called arc discharge. An arc discharge is an electric discharge phenomenon of a gas and refers to current released in air. When the voltage applied to two spatially separated electrodes is gradually increased, the air insulation finally breaks and current flows between the electrodes, emitting bright light and high heat at the same time. The generated arc-shaped light is called an electric arc or arc. Arc welding is welding using the heat of an arc as a heat source.
In arc welding, positive voltage is applied to the electrode (welding rod/wire) and negative voltage is applied to the base material. This makes an arc occur from the base material to the electrode.
The output current of the arc is about 5 to 1,000 A and the output voltage is about 8 to 40 V. The temperature of the arc is about 5,000°C to 20,000°C. The melting temperature of iron is about 1,500°C. Consequently, the base material and electrode are heated to a high temperature and fuse together.

Mechanism of arc welding
  1. Arc
  2. Weld