Stir zone material flow patterns during friction stir welding of heavy gauge AA5056 workpieces and stability of its mechanical properties

OBRABOTKAMETALLOV Vol. 23 No. 4 2021 152 MATERIAL SCIENCE Stir zone material fl ow patterns during friction stir welding of heavy gauge AA5056 workpieces and stability of its mechanical properties Tatiana Kalashnikova 1, 2, a, * , Vladimir Beloborodov 1, b , Kseniya Osipovich 1, c , Andrey Vorontsov 1, d , Kirill Kalashnikov 1, e 1 Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences, 2/4, pr. Akademicheskii, Tomsk, 634055, Russian Federation 2 National Research Tomsk State University, 36 Lenin ave., Tomsk, 634050, Russian Federation a https://orcid.org/0000-0002-0388-4011 , gelombang@ispms.tsc.ru , b https://orcid.org/0000-0003-4609-1617, vabel@ispms.ru , c https://orcid.org/0000-0001-9534-775X , osipovich_k@ispms.ru, d https://orcid.org/0000-0002-4334-7616, vav@ispms.tsc.ru, e https://orcid.org/0000-0002-0286-7156, kkn@ispms.tsc.ru Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2021 vol. 23 no. 4 pp. 140–154 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2021-23.4-140-154 Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov ARTICLE INFO Article history : Received: 16 September 2021 Revised: 28 September 2021 Accepted: 05 October 2021 Available online: 15 December 2021 Keywords : Friction stir welding Friction stir processing Structural-phase state Mechanical properties Funding The results were obtained in the framework of the Integrated Project “Establishment of production of high-tech large-sized equipment for intelligent adaptive friction stir welding for the aerospace and transport industries of the Russian Federation” (Agreement No. 075- 11-2019-033 dated November 22, 2019) implemented by the NSTU and ISPMS SB RAS at the fi nancial support of the Ministry of Education and Science of the Russian Federation as part of Decree of the Government of the Russian Federation No. 218 dated April 09, 2010. ABSTRACT Introduction. Friction stir welding and processing are almost identical processes of severe plas- tic deformation at elevated temperatures. These technologies differ mainly in the purpose of its use: the formation of a hardened surface layer or producing a welded joint. However, it is known that both dur- ing welding and during processing of heavy gauge workpieces temperature gradients occur. As a result, the conditions of adhesive interaction, material plastic fl ow, and the formation of the stir zone change as compared to thin-sheet workpieces with fundamentally different heat dissipation rates. In this con- nection, the purpose of the work is to determine the regularities of the structure formation and sta- bility of the mechanical properties in different directions in the material of 35-mm-thick aluminum- magnesium alloy samples produced by friction stir welding/processing. Research Methodology. The technique and modes of friction stir welding and processing of AA5056 alloy workpieces with a thickness of 35 mm are described. Data on the equipment used for mechanical tests and structural research are given. Results and discussion. The data obtained show the excess mechanical properties of the processing zone material over the base metal ones in all studied directions. Material structure heterogeneities after friction stir welding/processing of heavy gauge workpieces have no determining effect on the stir zone properties. At the same time, there is no clear correlation between the tensile strength values and the load application direction, nor is there any signi fi cant difference in mechanical properties depending on the location of the samples inside the stir zone. The average ultimate tensile strength values in the vertical, transverse, and longitudinal direc- tions are 302, 295 and 303 MPa, respectively, with the yield strength values of 155, 153 and 152 MPa, and the relative elongation of 27.2, 27.5, 28.7 %. For citation: Kalashnikova T.A., Beloborodov V.A., Osipovich K.S., Vorontsov A.V., Kalashnikov K.N. Stir zone material fl ow patterns during friction stir welding of heavy gauge AA5056 workpieces and stability of its mechanical properties. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science , 2021, vol. 23, no. 4, pp. 140–154. DOI: 10.17212/1994-6309-2021-23.4- 140-154. (In Russian). ______ * Corresponding author Kalashnikova Tatiana A. , Research Of fi cer Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences, 2/4, pr. Akademicheskii, 634055, Tomsk, Russian Federation Tel.: 8 (382) 228-68-63, e-mail: gelombang@ispms.ru