Fririction Shear Welding
Modified friction welding process deployed particularly for repair operations and joining sheet metal via thermomechanical shear action.
In friction welding, the heat is generated purely by mechanical friction. You press the parts together and rub them against each other until the material at the contact surface becomes plastic. Then you forge the parts together firmly, and the joint is done. The whole process takes place in the solid state, so the material doesn't really melt. This gives you a very clean and strong weld without needing filler material or shielding gas. It's important that the surfaces are clean and free of grease, otherwise you won't get a clean weld. Parameters like rotational speed and forging pressure must be set according to the material and part size. If you apply too much pressure or rub too fast, things get too hot and can lead to precipitations or cracks. Better to start more gently and develop a feel for the right upsetting.