Obrabotka Metallov 2018 Vol. 20 No. 3

OBRABOTKAMETALLOV Vol. 20 No. 3 2018 132 MATERIAL SCIENCE References 1. Sharma R.S., Molian P. Weldability of advanced high strength steels using an Yb:YAG disk laser. Journal of Materials Processing Technology, 2011, vol. 211, iss. 11, pp. 1888–1897. doi: 10.1016/j.jmatprotec.2011.06.009. Structural Features of Laser Welded 13Mn6 Constructional Steel Alexander Kolubaev 1, а,* , Olga Sizova 1, b , Evgeny Kolubaev 1, c , Anastasia Zaikina 1, d , Andrey Vorontsov 1, e , Yuliya Denisova 1 ,2, f , Valery Rubtsov 1, e 1 Institute of Strength Physics and Materials Science of the Siberian Branch of the RAS, 2/4 pr. Akademicheskii, Tomsk, 634055, Russian Federation 2 Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, 2/3 Akademichesky Avenue, Tomsk, 634055, Russian Federation а https://orcid.org/0000-0002-2839-5249, kav@ispms.tsc.ru , b https://orcid.org/0000-0001-9177-6602, ovs@ispms.ru , c https://orcid.org/0000-0001-7288-3656, eak@ispms.tsc.ru, d https://orcid.org/0000-0001-8507-3417, aaz@ispms.tsc.ru, e https://orcid.org/0000-0002-4334-7616, vav@ispms.tsc.ru , f https://orcid.org/0000-0002-3069-1434, yukolubaeva@mail.ru , g https://orcid.org/0000-0003-0348-1869, rvy@ispms.tsc.ru Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2018 vol. 20 no. 3 pp. 123–133 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2018-20.3-123-133 Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov ARTICLE INFO Article history : Received: 14 June 2018 Revised: 03 July 2018 Accepted: 15 August 2018 Available online: 15 September 2018 Keywords : Laser welding Constructional steel Welded joint Dendrite structure Microstructure Defects Tensile strength Funding : This work was financially supported by Russian Federation Ministry of Education and Science (agreement No 14.607.21.0190, project identifier RFMEFI60717X0190) ABSTRACT Introduction. The technological process of manufacturing products made from structural steels is often complicated by the poor quality of welded joints during arc and gas flame welding due to high residual stresses and deformation caused by a high level of heat input into the welding zone. The example of an effective solution of this problem is development and adaptation of advanced joining techniques such as laser welding as a method of fuse welding. Due to high-power density and welding speed, as well as narrow heat-affected zone, laser welding provides lowest deformation of welded joints. Laser welding, as an advanced technology, is applied for various metals joining. Goal of research is to reveal the regularities in the formation of the crystallographic structure of welds of structural steel plates 13Mn6, formed as a result of laser welding, including the ultrasonic treatment during welding process, to conduct analysis of the defects formed and to perform the tensile tests. Results and Discussion. Optical and scanning electron microscopy results revealed gradient structure of the welds, which is characterized by the presence of a fusion zone, an overheating zone located on the boundary with a molten metal zone but not melted, and a normalization zone with a fine-grained structure. The fusion zone is formed by dendrites oriented toward the center of the weld. The internal structure of dendrites consists of packets with a rack structure, formed as a result of the γ→α transformation. The spaces between the racks are separated by interlayers, consisting, presumably, of residual austenite. The overheating zone is characterized by a coarse-grained ferritic structure with a ferrite of the Widemanstatten type, which needles come up from the boundaries into the interior of the main grain. A fine-grained ferrite-perlite structure in the normalization zone indicates the complete phase-recrystallization of the grain of the initial steel. When varying the laser power and the welding speed, it was found that the defectiveness of the welds is more affected by the welding speed. The ultrasonic treatment in the process of fusion penetration made it possible to eliminate large pores formed in the welds. For citation: Kolubaev A.V., Sizova O.V., Kolubaev E.A., Zaikina A.A., Vorontsov A.V., Denisova Yu.A., Rubtsov V.E. Structural features of laser welded 13Mn6 constructional steel. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science , 2018, vol. 20, no. 3, pp. 123–133. doi:10.17212/1994-6309-2018-20.3-123-133. (In Russian). ______ * Corresponding author Kolubaev Alexanler V., D.Sc. (Engineering), Professor Institute of Strength Physics and Materials Science of the Siberian Branch of the RAS 2/4, pr. Akademicheskii Tomsk, 634055, Russian Federation Tel.: 8 (382) 228–69–70, e–mail: kav@ispms.ru