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Generally, the tubes used in internal high-pressure forming must not only meet the mechanical properties required for the structure, but also satisfy the forming properties as well as the accuracy of diameter and wall thickness. In terms of formability, high plasticity as well as large values for n and r are required. The processing method of the pipe material has a significant impact on its mechanical and formability properties. Pipes used for internal high-pressure forming require that processing hardening be minimized during manufacturing, so as to retain as much plasticity in the material as possible and increase the r value, thereby facilitating subsequent internal high-pressure forming. The precision requirements for the outer diameter and wall thickness of internally pressurized formed pipes are often higher than those for steel pipes used in ordinary applications. It is determined based on the sealing method used in the molding process and the required precision of the part wall thickness. Generally, the outer diameter and wall thickness tolerances of precision hot-rolled and cold-rolled steel pipes meet the requirements for internal high-pressure forming, and the tolerances of resistance-welded pipes also easily satisfy these requirements. If there are differences in the tolerances among different batches of pipes, this can also be resolved by adjusting the dimensions of the mold. The pipe end must be cut perpendicular to the pipe’s centerline, with the deviation of the end face from this centerline being within 1.5°. Internal high-pressure formed pipes also have cleanliness requirements; both the inner and outer walls of the pipes must be highly clean. The surface of the steel pipe should be pickled to ensure there is no rust. In internal high-pressure forming, the oxide scale and rust on the surface of the tube can cause wear to the die and contaminate the pressurized medium. Various kinds of debris present on the inner and outer surfaces of the tubing can fall into the mold cavity and be pressed into the surface of the formed part, affecting the quality of the part.