ОЦЕНКА ВОЗМОЖНОСТИ ПРИМЕНЕНИЯ ПОДСТУЖИВАНИЯ ЗАГОТОВКИ ДЛЯ БОРЬБЫ С НЕОДНОРОДНОСТЬЮ ДЕФОРМАЦИЙ ПО ВЫСОТЕ ЗАГОТОВКИ

D. V. Perevozchikov; L. V. Radionova

doi:10.14529/met180105

Authors

D. V. Perevozchikov South Ural State University, Chelyabinsk; PJSC Chelyabinsk Pipe-Rolling Plant, Chelyabinsk
L. V. Radionova South Ural State University, Chelyabinsk

DOI:

https://doi.org/10.14529/met180105

Keywords:

inhomogeneity of temperature field, calling-dawn of billet, Inhomogeneity of structure by graine size, piercing pipes, finite difference methods

Abstract

In the article considers the problem of the heterogeneity of grain caused by the dissipation of stresses and non-uniform examination of the high deformation zone. To reduce the inhomogeneous deformation in the work it is proposed to use forced calling-dawn to create more hot and pliable to deform the middle billet. The paper also notes that calling-dawn can be reason of freezing the sidewall billet. To estimate the temperature field in the workpiece, a mathematical model of cooling on the workpiece is developed. The mathematical model is based on the solution of the heat equation by finite difference method. At the decision the four-point implicit scheme of Samarskii is used. The problem is solved in the cylindrical coordinate system, and takes into account the cooling in the radial direction and length. As boundary conditions, the symmetry conditions, the temperature derivative equality at the coordinate zero, and on the surface the mixed boundary condition considering radiation according to the Stefan-Boltzmann law and convective heat exchange according to the Newton-Richmann law are used. It is proposed to use shielding of radiated energy to reduce end face hardening. A formula is given to estimate the conditional emissivity factor, taking into account the reflected energy screen. In the article calculations of the temperature field according to the method given in the work are carried out. Also the estimation of the difference of the resistance to plastic deformation according to the law of the Zener-Holomon subject to a constant strain and rate of deformation. The conclusion about the futility of the use of calling-dawn of the workpiece in the described way in order to deal with heterogeneity of deformation. After the calculation it was found that short-term calling-dawn of the workpiece with the use of screens can lead to the small alignment of the temperature field along the length of the workpiece.

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