All-Russian Scientific Research Institute of Aviation Materials at the Kurchatov Institute National Research Centre, Moscow, Russia

T. A. Shlyapnikova, Deputy Head of Laboratory, Candidate of Technical Science
A. V. Somov, Lead Engineer, e-mail: andrey-somov@inbox.ru
A. L. Ivanov, Lead Engineer
A. A. Selivanov, Head of Laboratory, Candidate of Technical Science

Development of advanced high-strength aluminium alloys is one of the most relevant problems in the area of aviation materials, aimed at enhanced weight efficiency and durability of new-generation air- and spacecrafts. This paper looks at the effect of temperature and time parameters of artificial ageing on the properties and structure of extruded sections made of alloy V-1977 up to 60 mm thick, with the aim to identify a heat treatment regime that would ensure the desired combination of properties. The authors used optical and scanning electron microscopy to examine the structure and phase state of V-1977 sections. It was found that maximum strength is reached after the first ageing step as a result of precipitation of disperse particles of the strengthening phase, whereas the alloy loses some strength after the second ageing step as these particles get bigger. As part of this study, the authors determined the tensile properties, as well as corrosion resistance and fracture toughness of extruded V-1977 sections after a one- and two-step ageing process. The parameters of the two-step (T2) artificial ageing of extruded V-1977 sections were established that ensure a high strength (σ_в = 700 MPa, σ_0.2 = 675 MPa), acceptable corrosion resistance (proneness to layer corrosion — 4 points, to intercrystalline corrosion — max. 60 μm) and high fracture toughness (37.2 MPa·m^1/2), which are necessary for basic structural components of new-generation air- and spacecrafts.
This research was carried out as part of implementing Comprehensive Research Initiative 8.1 “High-Strength Weldable Aluminium and Aluminium-Lithium Alloys with Low Density and High Fracture Toughness” (“Strategic Areas for the Development of Materials and Processing Techniques for the Period till 2030”), under Governmental Contract No. 21411.1770290019.18.008 dated 01/03/2021.

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