High-Frequency Resistance Welding
High-frequency resistance welding heats metal edges by a rapid, high-frequency electric current. It is ideal for longitudinal seam pipes and avoids heat wear.
Physicochemical Mechanism of Action
The current flow in the weld zone is generated by high-frequency alternating currents that switch on and off rapidly. This leads to rapid heating of the metal edges without simultaneous fusion of the entire material.
Metallurgical Relevance & Risks in Welding
This process prevents fusion and the increase of porosity, resulting in a fine-grained structure. It also reduces heat wear on electrodes and in the workshop. However, inaccurate current regulation can lead to uneven heating or excessive stress, causing cracks or damage to the pipe.
Workshop Practice & Instructions
Use high-frequency alternating currents with a frequency of at least 50 kHz. Ensure electrodes are clean and provide good contact surface. Adjust the current so that edges are heated without melting the pipe. Typical heating time is 1 to 2 seconds per meter of pipe length.