Rotational Friction Stir Welding
Rotary friction stir welding is a solid-state joining process where a rotating pin tool softens and plastically mixes the material through frictional heat. It prevents fusion defects in light metals.
Physical-Chemical Mechanism of Action
Rotary friction stir welding uses the frictional heat between a pin tool and the material being welded. This friction generates enough heat to locally soften the material and mix it plastically. This process occurs without fully melting the material.
Metallurgical Relevance & Risks in Welding
This process is especially suitable for light metals like aluminum or copper, where full melting can lead to fusion defects. It prevents the formation of pores and improves joint strength. However, insufficient frictional heat conditions can result in the joint not being plastically mixed well enough, leading to poor weld quality.
Workshop Practice & Instructions
To successfully perform rotary friction stir welding, it is important that the pin tool be made of a hard material such as diamond or cobalt. The rotation speed and the downward force must be precisely adjusted. A typical speed range is 100 to 200 rpm, with a downward force of 50 to 100 N. It is also important to regularly clean the tool to ensure optimal friction.