Papers by Author: M.A. Tsepin

Abstract: Blank punch was applied for manufacturing of hollow billets by press piercing. Analysis of piercing by different punches was carried out. Data showing fluctuating of load during piercing and changing of billet’s shape was received.

Abstract: In the present work, there are presented the results of experimental studies on the basis of regression analysis and FEM-based modeling of the processes of aluminum alloys preforms and semi-finished products manufacture including such widely known processes as cutting rolled products by shear and thixotropic stamping (stamping of metal during crystallization). It is investigated the influence of technological heredity created by variation of cant angles of end surfaces and mono- and poly-directional pulling-down by shear in cutting rolled blanks on stability of the process of subsequent longitudinal upsetting while producing preforms for bulk stamping. As a result of studying the ways of eliminating such negative consequences of technological heredity and increasing high-strength aluminum alloys technological plasticity, there is revealed the possibility of using phase transitions (from solid to liquid state and back) while manufacturing semifinished products in thixotropic conditions close to superplastic deformation.

Abstract: The variety of metal forming processes can be arranged according to some essential features such as structure, properties and structure evolution of the metal being deformed, deformation temperature and dynamics of its changing during deformation, interrelation between flow stress, strain and strain rate, temperature and structural parameters etc. These features in the aggregate compose rheological behavior of the metal being deformed and the rheological equation’s database for simulation of metal forming processes in cold, warm, hot and superplastic state. Taking these ideas into account, the authors would like to present some basic elements of these rheological models database i.e. classification of metallic materials as objects of deformation, classification of deformation modes in dependence on temperature regimes, thermal-kinetic map of metal processing and, as a result of this analysis, a set of rheological models related to certain modes of metal forming processes, which can be used as basic elements of computer software systems for simulation of these processes.

Abstract: There are presented original experimental results of studying rheological behavior of Vitralloy 1 (Zr41Ti14Cu12.5Ni10Be22.5), which shows in the certain strain rate range stable linear viscous (Newtonian) flow. Comparative analysis of these results and the results related to other superplastic alloys as well as to crystallizing metallic melts has been carried out.