The two edges of the billet are heated to welding temperature and, under the pressure of the extrusion rolls, form a solid weld by allowing the metal grains to interpenetrate and crystallize together. If the extrusion pressure is too low, fewer interpenetrating crystals are formed, resulting in reduced metal strength of the weld, which may crack under stress. On the other hand, if the extrusion pressure is too high, molten metal may be forced out of the weld, not only lowering the weld strength but also causing numerous burrs inside and out, potentially leading to defects like gaps in the weld.

4 Frequency induction coil position adjustment

The high-frequency coil should be as close as possible to the extrusion roller position. If the coil is too far from the extrusion roller, the effective heating time is longer, the heat-affected zone is wider, and the weld strength decreases; conversely, the lack of heating at the weld edge results in poor shaping after extrusion.