"Suchasna Elektrometallurgiya" (Electrometallurgy Today), 2026, #1, 53-63 pages
Microstructure and phase composition of joints of cast and wrought nickel superalloys produced by friction welding
I.V. Ziakhor
, A.M. Levchuk

E.O. Paton Electric Welding Institute of the NAS of Ukraine
11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine.
E-mail: zyakhor2@ukr.net
Abstract
For domestic manufacturers of aviation gas turbine engines (GTEs), the development of efficient technologies for
welding nickel superalloys remains an important challenge, particularly for friction welding of “disk–blade” (blisk-type)
components. The paper presents the results of a study on the formation of dissimilar joints between cast alloy VZhL12U
and wrought alloy EI698VD produced by friction welding. Experimental methods were used to investigate the influence
of friction welding process parameters and post-weld heat treatment (HT) conditions on the joint microstructure and
the morphology of strengthening phase particles, including carbides and the γ′-phase. The experiments were carried
out on superalloy specimens with a diameter of 24 mm. A hybrid friction welding technology was applied with varying
durations of rotation braking during the forging stage in the range of tbr = 0.3–3.0 s. It was established that an increase
in tbr significantly affects structural and phase transformations in the thermomechanically affected zone (TMAZ) of the
joints. In particular, at tbr = 3.0 s, dissolution of both secondary dispersed γ′-phase particles and thermally stable primary eutectic γ′-phase on the side of the cast alloy VZhL12U occurs during the forging stage. A heat treatment mode was
determined that ensures restoration of the γ′-phase particle morphology on the side of the EI698VD alloy and eliminates
regions of reduced microhardness within the joint zone. The phenomenon of an anomalous increase in the size of
dispersed γ′-phase particles in the TMAZ of the VZhL12U alloy after a three-stage HT (according to the specifications
for EI698VD alloy) was also observed. 25 Ref., 2 Tabl., 13 Fig.
Keywords: nickel superalloys, friction welding, joints, microstructure, heat treatment, γ′-phase, carbides,
microhardness
Received: 02.04.2026
Received in revised form: 06.04.2026
Accepted: 31.03.2026
Posted online: 14.04.2026
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Suggested Citation
I.V. Ziakhor, A.M. Levchuk (2026) Microstructure and phase composition of joints of cast and wrought nickel superalloys produced by friction welding.
Electrometallurgy Today, 01, 53-63.
https://doi.org/10.37434/sem2026.01.07