| KINEMATIC VISCOSITY, SURFACE TENSION, and DENSITY of PIPE STEEL in LIQUID STATE Vladimir Tsepelev1; Yuri Starodubtsev2; Kai-ming Wu3; Nadezda Konovalova4; 1BORIS YELTZIN URAL FEDERAL UNIVERSITY, Ekaterinburg, Russian Federation; 2GAMMAMET RESEARCH & PRODUCTION ENTERPRISE, Ekaterinburg, Russian Federation; 33INTERNATIONAL RESEARCH INSTITUTE FOR STEEL TECHNOLOGY, WUHAN UNIVERSITY OF SCIENCE AND TECHNOLOGY, Wuhan, China; 4BORIS YELTSIN URAL FEDERAL UNIVERSITY, Ekaterinburg, Russian Federation; PAPER: 195/Metals/Regular (Oral) SCHEDULED: 12:20/Tue. 29 Nov. 2022/Arcadia 1 ABSTRACT: Pipe steel must have high strength, toughness and ductile-brittle transition temperature. To achieve these indicators, the steel has a limited C content, not more than 0.24 wt. %, Mn, no more than 1.4 wt. %, and Si, no more than 0.6 wt. % and this content depends on the strength class of pipe steel. For grain refinement, pipe steel is alloyed with Al, Nb, Ti, V in an amount of not more than 0.15 wt. %. To increase the corrosion resistance, steel may contain a limited amount of Cr, Ni, Mo, Cu. The minimum level should be the content of harmful impurities P, S, N. As a rule, the content of alloying elements and impurities in pipe steel does not exceed 2 wt. %, so this steel can be called a multicomponent low alloyed steel. The structure of multicomponent melts has a significant effect on the physical properties of steel [1]. Multicomponent melts have a heterogeneous structure [2], which manifests itself in the features of the temperature dependences of the kinematic viscosity. When the melt is heated above the temperature Th, the heating and cooling curves diverge at T < Th. There is a temperature region near Th, within which the heating and cooling curves form a hysteresis loop [3]. The critical temperature Tk separates regions with different activation energies for viscous flow. The work investigated the temperature dependences of the kinematic viscosity, surface tension and density in liquid pipe steel. Evaluation of the thermophysical properties of liquid pipe steel was carried out in terms of the cluster size, which are structural components of the melt. The cluster size was calculated using the formula for the kinematic viscosity obtained in the transition state theory [4]. From Arrhenius plots, the activation energy and pre-exponential factor were determined. The relative free volume was found from the Batschinsky relationship [5]. It is shown that the activation energy Ea increases with an increase in the cluster size. This relationship allows one to explain the anomalous behavior of the temperature dependence of the kinematic viscosity. The local change in the viscosity is caused by the decomposition of clusters and the subsequent formation of new clusters of a different size and chemical composition. The viscosity at the cooling stage corresponds to the melt structure formed at the maximum heating temperature. The relationship between the surface tension and the chemical composition in the surface layer of the melt is shown. The melt heating temperature is recommended to obtain the optimal structure of the pipe steel. References: [1] B.A. Baum, G.A. Khasin, G.V. Tyagunov, Ye.A. Klimenkov, Yu.A. Bazin, L.V. Kovalenko, V.B. Mikhailov, G.A. Raspopov, Liquid Steel,Moscow, Metallurgia, 1984. [2] M. Calvo-Dahlborg, P.S. Popel, M.J. Kramer, M. Besser, J.R. Morris, U. Dahlborg, J. Alloys Comp. 550 (2013) 9–22. [3] V.S. Tsepelev, Yu.N. Starodubtsev, Nanomaterials 11 (2021) 00108. [4] V.S. Tsepelev, Yu.N. Starodubtsev, K.M. Wu, Ye.A. Kochetkova, Key Eng. Mater. 861 (2020) 107–112. [5] V.Tsepelev, Yu. Starodubtsev, V. Konashkov, K. Wu, R. Wang, J. Alloys Comp. 790 (2019) 547–550. |
