{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,16]],"date-time":"2026-01-16T10:02:32Z","timestamp":1768557752282,"version":"3.49.0"},"reference-count":37,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2024,11,12]],"date-time":"2024-11-12T00:00:00Z","timestamp":1731369600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan","award":["AP19676903"],"award-info":[{"award-number":["AP19676903"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>Traditionally, structural wire is characterized by a homogeneous microstructure, where the average grain size in different parts of the wire is uniform. According to the classical Hall\u2013Petch relationship, a homogeneous polycrystalline metal can be strengthened by decreasing the average grain size since an increase in the volume fraction of grain boundaries will further impede the motion of dislocations. However, a decrease in the grain size inevitably leads to a decrease in the ductility and deformability of the material due to limited dislocation mobility. Putting a gradient microstructure into the wire has promising potential for overcoming the compromise between strength and ductility. This is proposed a new combined technology in this paper in order to obtain a gradient microstructure. This technology consists of deforming the wire in a rotating equal-channel step die and subsequent traditional drawing. Deformation of copper wire with a diameter of 6.5 mm to a diameter of 5.0 mm was carried out in three passes at room temperature. As a result of such processing, a gradient microstructure with a surface nanostructured layer (grain size ~400 nm) with a gradual increase in grain size towards the center of the wire was obtained. As a result, the microhardness in the surface zone was 1150 MPa, 770 Mpa in the neutral zone, and 685 MPa in the central zone of the wire. Such a symmetrical spread of microhardness, observed over the entire cross-section of the rod, is a direct confirmation of the presence of a gradient microstructure in deformed materials. The strength characteristics of the wire were doubled: the tensile strength increased from 335 MPa to 675 MPa, and the yield strength from 230 MPa to 445 MPa. At the same time, the relative elongation decreased from 20% to 16%, and the relative contraction from 28% to 23%. Despite the fact that the ductility of copper is decreased after cyclic deformation, its values remain at a fairly high level. The validity of all results is confirmed by numerous experiments using a complex of traditional and modern research methods, which include optical, scanning, and transmission microscopy; determination of mechanical properties under tension; and measurement of hardness and electrical resistance. These methods allow reliable interpretation of the fine microstructure of the wire and provide information on its strength, plastic, and electrical properties.<\/jats:p>","DOI":"10.3390\/sym16111515","type":"journal-article","created":{"date-parts":[[2024,11,12]],"date-time":"2024-11-12T05:21:59Z","timestamp":1731388919000},"page":"1515","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Obtaining Symmetrical Gradient Structure in Copper Wire by Combined Processing"],"prefix":"10.3390","volume":"16","author":[{"given":"Andrey","family":"Volokitin","sequence":"first","affiliation":[{"name":"Department of Metal Forming, Karaganda Industrial University, Temirtau 101400, Kazakhstan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2190-5672","authenticated-orcid":false,"given":"Irina","family":"Volokitina","sequence":"additional","affiliation":[{"name":"Department of Metallurgy and Material Science, Karaganda Industrial University, Temirtau 101400, Kazakhstan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7766-1198","authenticated-orcid":false,"given":"Mehmet Seref","family":"Sonmez","sequence":"additional","affiliation":[{"name":"Department of Metallurgical and Materials Engineering, Faculty of Chemistry and Metallurgy, Istanbul Technical University, Sariyer, Istanbul 34469, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anastassiya","family":"Denissova","sequence":"additional","affiliation":[{"name":"Department of Metal Forming, Karaganda Industrial University, Temirtau 101400, Kazakhstan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zoya","family":"Gelmanova","sequence":"additional","affiliation":[{"name":"Department of Management and Business, Karaganda Industrial University, Temirtau 101400, Kazakhstan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,11,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2985","DOI":"10.1016\/j.jmrt.2024.07.038","article-title":"Gradient microstructure formation in carbon steel bars","volume":"31","author":"Volokitina","year":"2024","journal-title":"J. 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