High-Frequency Upset Welding

In high-frequency pressure welding, you heat the workpiece edges contactlessly by induction until they are welding-hot. Then you press the parts together with plenty of force, and the joint forms in the solid state through diffusion. It's important that the edges are clean and free of scale or grease, otherwise the weld won't hold. Cooling should be controlled to avoid cracks or stresses in the material. If you work too fast or the pressure isn't right, the weld will be porous or cold.