National University of Science and Technology MISiS, Moscow, Russia:

A. Ya. Travyanov, Director of the Institute of Ecotechnology and Engineering, Candidate of Technical Sciences

A. O. Lagutin, Engineer
M. G. Khomutov, Senior Researcher, Candidate of Technical Sciences, e-mail: khomutov@misis.ru

Aviation Technology Park, Research & Production Association, Ufa, Russia:
V. V. Lukianov, Head of the Department, Candidate of Technical Sciences

Nowadays, the rapid development of the new methods of assembling large-scale parts consisting of several materials elaborated by different manufacturing methods is observed. These materials are unique in terms of the mechanical and physical properties of the part. Diffusion welding is one of the most promising multipurpose assembling techniques allowing the formation of lowporous high-quality welding joints with stable mechanical properties and absence of oxide inclusions. This method is widely applied for assembling titanium alloy parts requiring the welding in a vacuum due to the high chemical activity of titanium in the normal atmosphere containing oxygen, nitrogen and hydrogen. In this work, the structure and properties of parts produced from Ti6Al4V titanium alloy by the combination of laser powder bed fusion, hot rolling and diffusion welding were studied. The diffusion welding was performed in an autoclave (at temperature T = 920 ^оC, pressure 4 MPa, holding time of 4 h) and hot isostatic pressing (at temperature T = 930 ^оC, pressure 100 MPa, holding time of 2 h). It was shown that the microstructure of the weld joint depended on the welding method (autoclave or HIP). No defects in the zone of diffusion joints were observed in both cases. The impact toughness of samples obtained during hot isostatic pressing is higher than for the samples obtained in an autoclave. Both types of welded samples had high mechanical properties and met the requirements of GOST 23755–79 standard for bulk titanium samples.
The authors would like to thank V. V. Cheverikin, Candidate of Technical Sciences, MISiS, and P. V. Petrovskiy, Candidate of Technical Sciences, MISiS, for conducting metallography studies and discussing the results. This research was funded by the Ministry of Science and Higher Education of the Russian Federation. Within the framenork of the Government Resolution No. 218 based on the Agreement on subvention assignment No. 075-11-2019-058 dated 25.11.2019 “Establishing a production line for locally reinforced titanium alloy components designed to operate under high loads and temperatures as a part of innovative gas turbine engines“.

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