AWS Certified Welding Inspector — FundamentalsWelding ProcessesMedium
A CWI is reviewing a Weld Procedure Specification (WPS) for Friction Stir Welding (FSW) of a 6061-T6 aluminum alloy. The WPS specifies a travel speed of 10 inches per minute (ipm) and a tool rotation speed of 400 RPM. What is the primary purpose of the tool's rotation in FSW?
- ATo create frictional heat and stir the material for solid-state bonding.
- BTo generate an electric arc for melting the base metal.
- CTo provide shielding gas coverage to the weld zone.
- DTo mechanically cut and remove excess material from the joint.
Show answer & explanationAnswer & explanation
Correct answer: A. To create frictional heat and stir the material for solid-state bonding.
In Friction Stir Welding, the rotating tool generates significant frictional heat as it plunges into and traverses the joint. This heat plasticizes the material, and the tool's rotation then mechanically stirs this plasticized material, forging it together in a solid-state process without melting.
Why the other options are wrong
- B. FSW is a solid-state process; it does not involve an electric arc or melting of the base metal.
- C. FSW does not typically require shielding gas as it's a solid-state process and less susceptible to atmospheric contamination than fusion welding.
- D. While some flash material may be expelled, the primary purpose of rotation is not to cut or remove material, but to stir and forge the plasticized metal.
FSW Tool Rotation
The rotating tool in Friction Stir Welding is central to the process, generating heat and mechanically stirring the material to achieve a solid-state weld.
- Generates frictional heat.
- Plasticizes the base metal.
- Mechanically stirs and forges material.
- No melting occurs.
Memory trick: Spinning tool, hot mix, strong bond, no melt.