Process for manufacturing a tubular profile resistant to bending and flexible in torsion

The manufacturing method uses a round cross-section high-quality steel tube (1), which is subjected to a U-shaped cold-forming process at its central section (c), with localised heating of partial sections of the steel tube to a temperature of between 920 and 960 degrees C, before hardening in water at a temperature above the AC3 point , followed by a temperature of between 240 and 320 degrees C maintained for a duration of at least 20 minutes and subsequent surface hardening.