Actual Problems in Machine Building 2016 No. 3

Актуальные проблемы в машиностроении. 2016. №3 Инновационные технологии в машиностроении ____________________________________________________________________ 29 DEGRADATION OF STRUCTURE AND PROPERTIES OF SILUMIN SUBJECTED TO ELECTRON-BEAM TREATMENT AND HIGH-CYCLE FATIGUE TESTING Aksenova K.V. 1 , Ph.D. student, e-mail: alsaraeva_kv@physics.sibsiu.ru Gromov V.E. 1 , D.Sc. (Physics and Mathematics), Professor, e-mail: gromov@physics.sibsiu.ru Konovalov S.V. 1 , D.Sc. (Engineering), Associate Professor, e-mail: konovalov@physics.sibsiu.ru Ivanov Yu.F. 2 , D.Sc. (Physics and Mathematics), Professor, e-mail: yufi55@mail.ru 1 Siberian State Industrial University, 42 Kirov Street, Novokuznetsk, 654007, Russian Federation 2 Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, 2/3 Prospect Akademicheskii, Tomsk, 634055, Russian Federation Abstract Nowadays silumins find wide application in manufacturing of the critical parts working in regimes of cyclic deformations determining the failure even under insignificant loads. Practically they are not hardened by thermal treatment due to the small difference in solubility of silicon at high and low temperature therefore the most important methods of improving their strength and mechanical properties is modification. One of the promising and approved methods of modification of structure-phase states of surface layers of metals and alloys is electron-beam processing (EBP). The analysis of variation of structure-phase states and defect substructure of silumin subjected to electron beam processing followed by fatigue loading up to the failure was carried out by methods of transmission electron diffraction microscopy. It was established that EBP of silumin resulted in the formation of cellular crystallization structure in surface layer independent of irradiation regimes used. The following multi-cycle fatigue tests resulted in the failure of cellular crystallization structure accompanied by globularization of silicon particles. The tribology and strength properties of silumin surface after electron beam processing and fatigue tests were studied. It was revealed that multi-cycle fatigue tests result in reduction in nanohardness, increase in wear intensity and friction coefficient. It was shown that one of the main reasons of reduction in strength and tribological properties of silumin surface layer was intensive deformation of the material taking place under multi-cycle fatigue tests and leading to failure of high speed crystallization structure formed in EBP. Keywords Structure, phase composition, electron beam treatment, silumin, fatigue, cellular crystallization Funding This work was supported by a grant of the RF President for state support of young Russian scientists - doctors (MD-2920.2015.8 project) and state task № 3.1496.2014 / K.