Obrabotka Metallov 2018 Vol. 20 No. 2

OBRABOTKAMETALLOV Vol. 20 No. 2 2018 113 MATERIAL SCIENCE Investigation of the Influence of Energy Parameter of the Covered-Electrode Welding on the Impact Strength Characteristics and Cracking Resistance of the Welded Joints Obtained Yury Saraev 1, a, * , Sergey Gladkovsky 2, b , Sergey Lepikhin 2, c , Ivan Kamantsev 2, d , Alexey Lunev 1, e , Marina Perovskaya 1, f 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 Engineering Science Ural Branch of Russian Academy of Sciences, 34 Komsomolskaya str., Yekaterinburg, 630049, Russian Federation a http://orcid.org/0000-0002-9457-4309, litsin@ispms.tsc.ru , b http://orcid.org/0000-0002-3542-6242, gsv@imach.uran.ru, c http://orcid.org/0000-0002-0240-2164, lsv@imach.uran.ru d http://orcid.org/0000-0003-0775-4043, ks@imach.uran.ru, e http://orcid.org/0000-0002-0777-5357, agl@ ispms.tsc.ru , f http://orcid.org/0000-0003-2780-6023, mv_perovskaya@inbox.ru Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2018 vol. 20 no. 2 pp. 100–115 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2018-20.2-100-115 ARTICLE INFO Article history : Received: 17 March 2018 Revised: 27 March 2018 Accepted: 09 April 2018 Available online: 15 June 2018 Keywords : Welding Surfacing Fracture Impact strength Fracture toughness Energy parameters Arc Welded joints Acknowledgements : The authors are grateful to the staff of the IMASh UrB RAS Veselova V.E. for the performed fractographic studies and Kuteneva S.V. for the quantitative metallographic analysis of welds with the use of equipment of OJSC “Uralturbo” (Ekaterinburg). The results of the research presented in the paper were obtained using the equipment of the CUC “Plastometry” of the Urals Branch of the Russian Academy of Sciences. Funding : The research is executed with financial support of RSF, the project No. 16-19- 10010. ABSTRACT Justification: High-strength low-alloy steels are used in mechanical engineering, construction industry, shipbuilding, pipeline transport among others due to increased requirements for the performance characteristics of welded structures. The main method used in the construction of metal structures is arc welding, which has a significant impact on the properties of the weld zone, its structure and mechanical properties. At the same time, there is always a risk of various defects in the weld zone, which physical origin is diverse and difficult to predict. The purpose of the research is to find ways to improve performance of the high-duty structures by estimating the influence of energy parameters of the covered-electrode welding modes and the change of its control algorithms on the weld structure and the heat-affected zone, as well as the characteristics of the impact toughness and crack resistance of the resulting welded joints. Experiment technique: steel 09G2S specimen, obtained by electrode welding in the modes of direct current (DC) and low-frequency current modulation (LFM) are used to carry out tests. Optical microscopy combined with image analyzer is used to study the structure of welds, the heat-affected zone (HAZ) and the base metal (BM). As a part of the study the average grain size is determined. An analysis of fractures of different sections is carried out using scanning electron microscopy. Results: the assessment of the impact of the energy parameters of the covered-electrode welding modes on the characteristics of the impact toughness and crack resistance of welds, as the main indicators of the operational characteristics of the high-duty structures is taken. The dependence of the energy parameters of covered-electrode welding modes and the change of its control algorithms on the structure of the weld and heat affected zone is established. It is shown that the pulsed nature of changes in the energy parameters of the welding mode has a favorable effect on the heat capacity of the melt of the molten pool and the conditions of its crystallization. Testing of HAZ in static fracture toughness showed that all investigated compounds have high values in the whole temperature range: from +20 ℃ to -60 ℃ , even in the presence of defects such as fatigue cracks. The effective influence of welding performed in the low-frequency current modulation mode, as compared to DC welding, on the resistance to brittle fracture of welded joints made of low-carbon steels at low climatic temperatures is determined. Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov