The Influence of the Rolling Direction of AA5056 on the Microstructure and Properties of Weld Joints obtained by Friction Stir Welding

OBRABOTKAMETALLOV Vol. 22 No. 4 2020 134 MATERIAL SCIENCE The In fl uence of the Rolling Direction of AA5056 on the Microstructure and Properties of Weld Joints obtained by Friction Stir Welding Anastasia Gusarova 1, a, * , Valery Rubtsov 1, 2, b , Evgeny Kolubaev 1, 2, c , Vladimir Bakshaev 3, d , Yury Nikitin 3, 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 Novosibirsk State Technical University, 20 Prospekt K. Marksa, Novosibirsk, 630073, Russian Federation 3 SESPEL Cheboksary enterprise, CJSC, 36 Leningradskaya st., Cheboksary, 428021, Chuvash Republic, Russian Federation a https://orcid.org/0000-0002-4208-7584, gusarova@ispms.ru , b https://orcid.org/0000-0003-0348-1869, rvy@ispms.ru, c https://orcid.org/0000-0001-7288-3656, eak@ispms.ru, d https://orcid.org/0000-0001-9777-0164, vlba@sespel.com , e https://orcid.org/0000-0002-6514-7383, urni@sespel.com Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2020 vol. 22 no. 4 pp. 124–136 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2020-22.4-124-136 Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov ARTICLE INFO Article history : Received: 01 September 2020 Revised: 14 September 2020 Accepted: 21 September 2020 Available online: 15 December 2020 Keywords : Friction stir welding Rolled aluminum Rolling direction Microstructure 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 CJSC “Cheboksary enterprise “Sespel”, NSTU and the ISPMS SB RAS with 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. Heat emission and plastic deformation during friction stir welding (FSW) cause profound changes in the microstructure and structural properties of weld joints. The grain size, crystallographic texture evolution and second-phase precipitate are the most important microstructural changes during welding of aluminum alloys, which largely in fl uence the strength properties of weld joints. In addition to process- dependent parameters (instrument sump force, its rotation frequency, and travel rate) of the FSW process, a signi fi cant factor, determining the properties of the obtained weld joints, is also a mutual orientation of structural elements of the weld material and the direction of the instruments impact on the material during welding. In this regard, the purpose of the work is to analyze the combined in fl uence of the direction of the initial rolling and the instrument pressure during FSW on the structure and properties of weld joints from the AA5056 aluminum alloy. Methods. Research methods are mechanical tests for statistical tension, microhardness as well as metallographic analysis of the structure of welded joints. Results and discussion. As a result, it is established that at low values of the axial force on the instrument (7 kN), defects such as the joint line and voids are observed in welded joints both rolling and transverse directions. When the load increases from 8 kN to 12 kN, defect-free weld joints with enhanced mechanical properties form. It is determined that the rolling direction of AA5056 during FSW does not in fl uence the structure and tensile strength of the weld joints, but it in fl uences the relative elongation and microhardness. It is shown that in the stir zone of the weld joint, obtained by FSW in the transverse direction of AA5056 fl ats, the relative elongation is 1.3-2 times greater, and the microhardness is by 4-10% greater than that in the stir zone of weld joints, obtained by FSW in the rolling direction of AA5056 fl ats. For citation: GusarovaA.V., Rubtsov V. Е ., Kolubaev E.A., Bakshaev V. А ., NikitinYu.V. The in fl uence of the rolling direction ofAA5056 on the microstructure and properties of weld joints obtained by friction stir welding. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2020, vol. 22, no. 4, pp. 124–136. DOI: 10.17212/1994-6309-2020-22.4-124-136. (In Russian). ______ * Corresponding author Gusarova Anastasia V. , Postgraduate, Junior researcher Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences, 2/4 pr. Akademicheskii, 634055, Tomsk, Russian Federation Tel.: +7 (996) 937-71-35, e-mail: gusarova@ispms.ru