TMK Research, LLC, Chelyabinsk, Russia

N. V. Fokin, Deputy Head of the Laboratory of Drawing and Extrusion, e-mail: fokin@tmk-group.com
Ya. I. Kosmatsky, Dr. Eng., Deputy General Director for Scientific Work, e-mail: KosmatskiyYI@tmk-group.com

Volzhsky Pipe Plant, Volzhsky, Russia
A. S. Tumashev, Leading Process Engineer, Pipe Rolling Laboratory, e-mail: aleksandr.tumashev@tmk-group.com
V. V. Baykov, Leading Process Engineer, Pipe Rolling Laboratory, e-mail: vasiliy.baykov@tmk-group.com

Due to the rapid development of the nuclear industry and energy in the world, in recent years there has been a trend towards an increase in the market for seamless stainless-steel pipes in the Russian Federation. At the same time, the share of PJSC TMK, as a global supplier of pipe products, in this segment also tends to grow. A significant volume of commercial stainless pipes is produced using a modern pipe pressing unit according to the technological scheme with piercing of the original billet, including continuously cast, solid section. As in any other metal forming process, during the press piercing of workpieces, defects in the surface of the product may occur, in this case, sleeves for subsequent pressing on a horizontal pipe profile press. The causes and nature of the emerging surface imperfections can be different, due to both technological factors of production and the initial properties of the material. In the present work, the possible reasons for the occurrence of a specific defect of the inner surface, which is formed in the zone of the stripping of the metal of the extrusion, are analyzed. In order to confirm the possible causes and the degree of their influence on the formation of the failure of the extrusion, a computer simulation of the piercing process was implemented with the implementation of the variation of the main parameters that determine the probability of the formation of defects. Based on the simulation results, the tasks necessary for solving were determined and projects of technological measures were developed to reduce the likelihood of the appearance of the previously mentioned defects.

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