What is Fusion in Welding?
In welding, fusion is the process of melting together filler metal and base metal (substrate), or of melting base metal only. This melted material, called the weld pool, coalesces to form a metallurgical bond between the parts being joined. The amount of heat required to achieve fusion depends on the composition of the metals being welded and their thickness.
Fusion welding types
There are two main types of welding processes: fusion welding and solid-state welding:
- In fusion welding, the heat required for melting is generated by an electric arc between the filler metal electrode and the workpiece. The molten weld pool created by the arc forms the metallurgical bond between the parts being joined. Common examples of fusion welding processes include gas tungsten arc welding (GTAW), plasma arc welding (PAW), and shielded metal arc welding (SMAW).
- In solid-state welding, the heat required for melting is generated by friction between the surfaces of the parts being joined. This can be done by pressing the surfaces together with or without the use of an external force, or by passing an electric current through the contact area. The molten weld pool created by the friction forms the metallurgical bond between the parts being joined. Common examples of solid-state welding processes include resistance welding and ultrasonic welding.
Fusion welding is generally used for joining metals, while solid-state welding is more often used for joining plastics and other non-metallic materials.
What causes fusion in welding?
The amount of heat required to achieve fusion in welding depends on the composition of the metals being welded and their thickness. In general, fusion welding requires higher temperatures than solid-state welding.
What is the fusing of metal?
The process of melting together filler metal and base metal (substrate), or of melting base metal only, results in coalescence. The amount of heat required to achieve fusion depends on the composition of the metals being welded and their thickness.
What is non-fusion welding?
Non-fusion welding is a solid-state welding process that joins materials without melting them. This type of welding uses heat and pressure to create a metallurgical bond between the parts being joined. Common examples of non-fusion welding processes include resistance welding and ultrasonic welding.