Byelorussian Steel Works — Management Company of “Byelorussian Metallurgical Company” Holding (Zhlobin, Belarus):

Gerasimov Yu. L., Mag. Tech., e-mail: gtp1.icm@bmz.gomel.by
Avdeev S. V., Mag. Tech.

Gomel State Technical University named after P. O. Sukhoy (Gomel, Belarus):
Bobarikin Yu. L., Cand Eng.

The results of complex investigations of the effect of features of oxidized coating of piercing plugs, manufactured by Byelorussian Steel Works — Management Company of “Byelorussian Metallurgical Company” Holding, on their resistance are presented. Metallographic analysis of plug structure has been conducted in order to determine the causes of low resistance of piercing mill plugs. Chemical and phase composition of oxidized coating, distribution of the elements and identification of coating substructure are examined. It was established that internal extension stresses in coating and low level of micro-hardness of steel ground and oxide layer can be the causes of low operating resistance of piercing plugs. Comparative testings of plugs with different quality of oxidized coating are done. It was revealed that local red-brown colour of plugs is connected with presence of large hematite amount in oxide layer structure, while delaminations of coating upper layer are caused by internal extension, as a result of passed high-temperature annealing.

1. Vavilkin N. M., Bukhmirov V. V. Piercing mandrel. Moscow : MISIS, 2000. 128 p.
2. Romantsev B. A., Goncharuk A. V., Vavilkin N. M., Samusev S. V. Pipe manufacturing. Second edition, revised and enlarged. Moscow : Izdatelskiy dom MISiS, 2011. 970 p.
3. Iida S., Hidaka Y. Influence of iron oxide of carbon steel on lubricating properties in seamless pipe hot rolling and the effectiveness of borax application. Tetsu-to-Hagane/Journal of the Iron and Steel Institute of Japan. 2010. No. 9. pp. 550–556.
4. Makedonov S. I., Ermakova R. V., Kozlov V. M. High-temperature oxidation of piercing mill mandrels. Stal. 1989. No. 11. pp. 68–70.
5. Serin K., Pehle H. J. Improved service life for hot forming tools in seamless tube plants. Stahl und Eisen. 2014. Vol. 134, Iss. 11. pp. 161–174.
6. Available at: https://www.stahleisen.de/Portals/stahleisen/11-TTPehle_Originalversion.pdf
7. Senyakina A. S., Makarova O. A. Investigation of microhardness of piercing mill mandrel and its infl uence on wear resistance. Izvestiya VolgGTU. 2013. No. 20(123). pp. 60–62.
8. Severdenko V. P., Makushok E. M., Ravin A. N. Cinder during the hotforming method. Moscow : Metallurgiya, 1977. 208 p.
9. Hidaka Yasuyoshi, Simoda, Kazuhito et al. Piercing and rolling mandrel, method and technological line for its restoration. Patent No. 2446024 RU C2, IPC В21 В25/00. Sumitomo Metal Industries, 2008.
10. Suyazov V. M., Tarasova T. S. Investigation of piercing mandrel restoration methods. 12-th scientific and practical conference of teaching staff of VPI VolgGTU (Volzhskiy, 30–31 January 2013) : collection of materials. Volgograd, 2013. CD-ROM. pp. 99–101.
11. Vavilkin N. M., Goncharov V. S., Bodrov D. V. et al. Peculiarities of water-cooled mandrels’ wear during the piercing of alloyed steels. Izvestiya vuzov. Chernaya metallurgiya. 2009. No. 7. pp. 37–40.
12. Gerasimov Yu. L., Avdeev S. V., Bobarikin Yu. L. Perfection of grooving plug of 120 mm dia for workpieces piercing at two-high helical rolling mill. Metallurg. 2015. No. 9. pp. 62–65.