Obrabotka Metallov 2018 Vol. 20 No. 3

OBRABOTKAMETALLOV Vol. 20 No. 3 2018 106 MATERIAL SCIENCE References 1. Panin V.E., Panin A.V., Pochivalov Yu.I., Elsukova T.F., Shugurov A.R. Scale invariance of structural transformations in plastically deformed nanostructured solids. Physical Mesomechanics , 2017, vol. 20, iss. 1, pp. 55– 68. doi: 10.1134/S1029959917010052. 2. Oláh A., Croitoru C., Tierean M.H. Surface properties tuning of welding electrode-deposited hardfacings by laser heat treatment. Applied Surface Science , 2018, vol. 438, pp. 41–50. doi: 10.1016/j.apsusc.2017.10.090. Simulation of Atomic Mechanisms of Nucleation and Development of Plastic Deformation under Conditions of Shear Loading Anton Nikonov a, * Institute of Strength Physics and Materials Science SB RAS, 2/4 Prospect Akademicheskiy, Tomsk, 634055, Russian Federation a http://orcid.org/0000-0002-0980-0317, anickonoff@ispms.ru Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2018 vol. 20 no. 3 pp. 97–108 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2018-20.3-97-108 Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov ARTICLE INFO Article history : Received: 18 June 2018 Revised: 23 July 2018 Accepted: 25 July 2018 Available online: 15 September 2018 Keywords : Plastic deformation Defect formation Molecular dynamics Shear deformation Local loading Funding The research was carried out with the financial support of the Program for Basic Scientific Research of the RAS on 2013-2020, Project III.23.2.4. ABSTRACT Introduction Methods of surface treatment of materials are one of the effective ways to improve its per- formance characteristics. One of the methods for finishing the surfaces of parts is the method of surface plastic deformation (nanostructuring burnishing), at which a layer with a nanocrystalline structure is formed. The study of the structural changes that occur directly in such burnishing process is extremely difficult. In this regard, numerical simulation methods can be an important addition to experimental studies. The purpose of the work is a numerical study of the mechanical response of a metal sample in a mono and nanoscale polycrystalline state to shear loading. In this paper, atomic mechanisms of nucleation and development of plastic deformation in a crystalline material under conditions of loading identical to local stresses arising during the processing of a material by surface plastic defor- mation are investigated . The methods of investigation. The research is carried out within the framework of high- performance parallel computations using the molecular dynamics method. The monocrystalline and polycrystalline body-centered cubic iron were chosen as the subject of research. Results and Discussion . The results of the studies show that under conditions of local shear loading in an initially defect-free α-iron crystal, it is possible to form a system of mutually intersecting dislocations, which subsequently leads to misorientation of individual parts of the crystallite and the formation of a nanofragmented structure of the surface layer. On the other hand, simulation data show that a shear in a nanoscale polycrystal is realized by the means of two competing mechanisms: grain boundary slip on one side and the process of recrystallization of individual grains on the other. With the growth of grains to di- mensions comparable with the size of the crystallite under study, the deformation in it begins to develop mainly due to the formation of structure defects, just as it occurs in a single crystal. Thus, the grain sizes and the orientation of its crystal lattice in relation to the direction of the external load determine the type of plastic deformation mechanisms of the surface material being realized. The obtained results can be used for a better understanding of the laws of processes and mechanisms realized in the surface layer of the material under surface plastic deformation conditions. For citation: Nikonov A.Y. Simulation of atomic mechanisms of nucleation and development of plastic deformation under conditions of shear loading. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science , 2018, vol. 20, no. 3, pp. 97–108. doi: 10.17212/1994-6309-2018-20.3-97-108. (In Russian). ______ * Corresponding author Nikonov Anton Yu. , Ph.D., Researcher Institute of Strength Physics and Materials Science of the Siberian Branch of the RAS, 2/4 pr. Akademicheskii, 634055, Tomsk, Russian Federation Tel.: 8 (3822) 286-973, e-mail: anickonoff@ispms.ru