To prevent the generation of internal carbunization and also to improve the quality of the inside surface by regulating the temp. of the inside of a material to be pierced just before rolling with the 2nd piercer (elongator) within a range of specific temp. and executing rolling while applying a nongraphitic lubricant on the inside surface or without the lubricant.

By regulating the rolling starting temp. of the elongator at 1100-1300°C at which a high-temp. ductility is obtained, inside rash of the elongater is prevented. The generation of carburization in the piecer is prevented by executing rolling while applying the nongraphitic lubricant on the inside surface or without the lubricant. When the temp. of the inside surface is lower, the ductility is lowered and the internal flaws such as inside rash is generated. When the temp. is too high, the ductility is eliminated by melting and the inside rash is generated. When a graphitic lubricant is used and the temp. of the material to be pierced before rolling is ≤1100°C, partial melting and CO gas are generated by heat generation by working at the time of rolling and the carburization of graphite is rapidly generated in the material to be pierced because the carbon content of the material to be pierced is small.