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| Effects of Electrically Assisted Forming on the Microstructure and Mechanical Properties of 7050 Aluminum Alloy Thin-Walled High-Ribbed Forgings |
| XING, Zi-Han, HU, Jian-Liang |
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1 College of Mechanical Engineering,
Yanshan University, Qinhuangdao 066004, China
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2 State Key Laboratory of Precision
Manufacturing for Extreme Service Performance, Central South University, Changsha
410083, China
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3 Deyang Wanhang Die Forging Co. Ltd., China National Erzhong Group,
Deyang 618013, China
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Cite this article:
XING, Zi-Han, HU, Jian-Liang. Effects of Electrically Assisted Forming on the Microstructure and Mechanical Properties of 7050 Aluminum Alloy Thin-Walled High-Ribbed Forgings. Acta Metall Sin, 0, (): 0-.
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Abstract 7050 aluminum alloy
thin-walled high-ribbed die forgings are essential structural components in
aerospace engineering, necessitating a lightweight design coupled with high
mechanical performance. However, conventional hot die forging often results in
a substantial microstructural gradient distribution, characterized by coarse
surface grains and severe inhomogeneity between the surface and core of the
forgings due to rapid surface cooling when the billet contacts the die. These
defects significantly degrade the mechanical properties and reliability of the
components. In addition, conventional process optimization methods cannot
fundamentally resolve these issues, often necessitating the removal of
unacceptable surface layers, which leads to considerable material waste. Pulsed
current-based electrically assisted forming (EAF) has demonstrated unique
advantages in regulating metal plastic deformation and microstructure via the
skin, electrothermal, and electroplastic effects. However, its systematic
application in complex thin-walled high-ribbed die forgings has not been
documented. To address these challenges, this study incorporates pulsed current
into the conventional hot die forging process, taking 7050 aluminum alloy
H-shaped thin-walled high-ribbed die forgings as the research object. Key
parameters include a pulse voltage of 400 V, pulse width of 50 μs, and
energizing time of 60 s. Two current frequencies, 600 and 1000 Hz, are selected
as experimental variables to assess the regulatory effects of EAF on the
microstructure and mechanical properties. The study employs finite element
simulations to analyze current density and temperature field distributions,
alongside multiscale experimental characterizations such as OM, EBSD, SEM, TEM,
and tensile testing. This comprehensive approach reveals the microstructural
evolution and strengthening mechanisms under electro-thermal-mechanical
multifield coupling. Results demonstrate that the 600-Hz medium-frequency EAF
process yields the optimal comprehensive regulation effect. The pulsed current
mitigates surface heat loss during die forging, facilitates sufficient dynamic
recrystallization, and generates uniform equiaxed grains throughout the
cross-section, thus eliminating microstructural inhomogeneity. Moreover, the electro-thermal-mechanical
coupling effect enhances solute solid solubility and boosts the contribution of
precipitation strengthening to yield strength, leading to simultaneous improvements
in strength and ductility. The mechanical properties of the surface and core of
the forgings are highly balanced, with yield strength, tensile strength, and
elongation measuring 495 MPa, 511 MPa, and 13.6% for the surface, and 492 MPa,
507 MPa, and 13.5% for the core, respectively. By contrast, the 1000-Hz
high-frequency current exacerbates the skin effect, causing excessive current
concentration on the surface and insufficient energy penetration into the core,
resulting in incomplete recrystallization and increased structural
inhomogeneity. Consequently, the mechanical properties of the 1000-Hz-processed
forgings are inferior and less uniform. This study elucidates the regulatory
mechanism of current frequency on the microstructural homogeneity and
mechanical properties of complex aluminum alloy die forgings under electro-thermal-mechanical
multifield coupling. The findings provide a novel and efficient technical
approach for integrated microstructure-performance control in high-strength
aluminum alloy thin-walled high-ribbed components, offering considerable
potential for reducing material waste and enhancing component reliability in
aerospace manufacturing.
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Received: 08 August 2025
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| Fund: National Natural Science Foundation of China(No. 52171018); Natural Science Foundation of Hebei Province(No. E2021203059); Central Guiding Local Science and Technology Development Fund Projects(No.236Z1016G); Open Research Fund of State Key Laboratory of Precision Manufacturing for Extreme Service Performance, Central South University(No. Kfkt2023-09); Open Research Fund of Sichuan Engineering Technology Research Center of Aviation Die Forgings.; Central Guiding Local Science and Technology Development Fund Projects(No.254Z4503G) |
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