Friction stir fillet welding
Specialized application of friction stir welding to produce T-joint and fillet configurations using specially shaped, wear-resistant shoulder and pin tools.
In friction stir fillet welding, you join two sheets at a right angle by guiding a rotating tool along the edge. The tool consists of a shoulder and a pin that plunges into the material. The friction makes the material plastic and mixes it without melting – so you don't need filler material. It's important that the tool matches the joint geometry exactly and is wear-resistant. If the pin doesn't sit cleanly in the corner or the shoulder is too small, the weld will be messy and the joint will lose strength. Keep the tool clean and guide it with steady pressure, then the fillet weld will be tight and strong.