The paper shows the results of metallographic examination and mechanical properties of electron beam welded joints of quenched and tempered S960QL and Weldox 1300 steel grades. The aim of this study was to examine the feasibility of producing good quality electron beam welded joints without filler material.
Metallographic examination revealed that the concentrated electron beam significantly affects the changes of microstructure in the weld and the adjacent heat affected zone (HAZ) in both steel grades. The microstructure of the welded joints is not homogeneous. The four zones, depending on the distance from the weld face, can be distinguished. Basically, the microstructure of the weld consists of a mixture of martensite and bainite. However, the microstructure of HAZ depends on the distance from the fusion line. It is composed of martensite near the fusion line and a mixture of bainite and ferrite in the vicinity of the base material.
Significant differences in mechanical properties of the welded joints were observed. For a butt welded joint of the S960QL steel grade the strength is at the level of the strength of the base material (Rm = 1074 MPa). During the bending test the required angle of 180° was achieved. The impact strength at −40°C was 71,7 J/cm2. In the case of the Weldox 1300 steel grade butt welded joints exhibit high mechanical properties (Rm = 1470 MPa), however, the plastic properties are on the lower level than for the base material.
 R. Willms, High strength steel for steel constructions, in: Nordic Steel Construction Conference, Malmo, Sweden, 2009.
 M.S. Węglowski, M. Zeman, Prevention of cold cracking in ultra-high strength steel Weldox 1300. Archives of Civil and Mechanical Engineering 14, 417-424 (2014).
 A. Grajcar, Thermodynamic analysis of precipitation processes in Nb-Ti-microalloyed Si-Al TRIP steel, Journal of Thermal Analysis and Calorimetry 118, 1011-1020 (2014).
 A. Grajcar, M. Rozanski, S. Stano, et al., Microstructure characterization of laser-welded Nb-microalloyed silicon-aluminum TRIP steel, Journal of Materials Engineering and Performance 23, 3400-3406 (2014).
 M.St. Węglowski, K. Krasnowski, K. Kwieciński, R. Jachym, The characteristics of Nd:YAG laser welded joints of dual phase steel, Archives of Civil and Mechanical Engineering 9, 85-97 (2009).
 A. Grajcar, M. Rozanski, S. Stano, et al., Effect of heat input on microstructure and hardness distribution of laser welded Si-Al TRIP-type steel, Advances in Materials Science and Engineering, Article Number: 658947 (2014).
 T. Wegrzyn, S. Wieszala, Significant alloy elements in welded steel structures of car body, Archives of Metallurgy and Materials 57, 45-52 (2012).
 A. Grajcar, W. Zalecki, et al., Dilatometric study of phase transformations in advanced high-strength bainitic steel, Journal of Thermal Analysis and Calorimetry 118, 739-748 (2014).
 M.S. Węglowski, S. Stano, G. Michta, W. Osuch, Structural characterization of Nd:YAG laser welded joint of dual phase steel, Archives of Metallurgy and Materials 55, 211-220 (2010).
 M.S. Węglowski, M. Zeman, M. Łomozik, Physical Simulation of Weldability of Weldox 1300 Steel, Materials Science Forum 762, 551-555 (2013).
 M. Gaspar, A. Balogh, GMAW experiments for advanced (Q+T) high strength steels. Production Processes and Systems 6, No 1, 9-24 (2013).
 H. Sumi, K. Oi, K. Yasuda, Effect of chemical composition on microstructure and mechanical properties of laser weld metal of high-tensile-strength steel, Welding in the World 59, 173-178 (2015).
 M.S. Weglowski, S. Błacha, A. Phillips, Electron beam welding – Techniques and Trends – Review. Vacuum 130, 72-92 (2016).
 V.E. Lazko, Mechanical properties and structure of welded joints in thick high-strength steel produced by electron beam welding and arc welding in a slit-like gap. Welding International 1, 566-569 (1987).
 G. Zhang, X. Yang, X. He, J. Li, H. Hu, Enhancement of mechanical properties and failure mechanism of electron beam welded 300M ultrahigh strength steel joints. Materials & Design 45, 56-66 (2013).
 S. Elliott, Electron beam welding of C/Mn steels – toughness and fatigue properties. Welding Journal 63, 8-16 (1984).
 X. He, X. Yang, G. Zhang, J. Li, H. Hu, Quenching microstructure and properties of 300M ultra-high strength steel electron beam welded joints. Materials & Design 40, 386-391 (2012).
 S. Schwantes, P. Gerster, K.R. Schulze, Schweißen der höchstfester Feinkornbaustählre S1100QL und S1300QL–Ein Vergleich des Elektronenstrahlschweißen an Atmosphäre mit einem Plasma-MSG-Hybridverfahren. Aachener Berichte Fügetechnik, 543-557 (2007).
 Fr.-W. Bach, A. Beniyash, K. Lau, R. Konya, Nonvacuum electron beam welding of structural steels. The Paton Welding Journal, No 5, 22-26 (2009).
 T. Hassel, R. Konya, et al., Economical joining of tubular steel towers for wind turbines employing non-vacuum electron beam welding for high-strength steels in comparison with submerged arc welding. Welding in the World 57, 551-559 (2013).
 PN-EN 10025-6:2009 Hot rolled products of structural steels – Part 6: Technical delivery conditions for flat products of high yield strength structural steels in the quenched and tempered condition.
 PN-EN ISO 148-1:2010 Metallic materials – Charpy pendulum impact test – Part 1: Test method.
 PN-EN ISO 9016:2013-05 Destructive tests on welds in metallic materials – Impact tests – Test specimen location, notch orientation and examination.
 PN-EN ISO 9015-1:2011 Destructive tests on welds in metallic materials – Hardness testing – Part 1: Hardness test on arc welded joints.
 PN-EN ISO 6507-1:2007 Metallic materials – Vickers hardness test – Part 1: Test method.
 PN-EN ISO 17639:2013-12, Destructive tests on welds in metallic materials – Macroscopic and microscopic examination of welds.
 PN-EN ISO 15614-11:2005 Specification and qualification of welding procedures for metallic materials. Welding procedure test. Part 11: Electron and laser beam welding.
 P. Seyffarth, R. Schmidt, W.F. Demtschenko, U. Jasnau, Simulation of microstructure – transformation – kinetics of unalloyed constructional steel in case of fast thermal cycles. Proceedings of the 3rd LANE 2001, Meisenbach Verlag, Bamberg, 2001.