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<p>This experimental study evaluates the applicability and effectiveness of Vortex Extrusion–Equal Channel Angular Pressing (Vo-CAP), a hybrid severe plastic deformation method, in processing AA7075 aluminum alloy. Unlike conventional multi-pass SPD techniques that require multiple processing cycles to obtain significant property improvements, Vo-CAP achieves superior mechanical property enhancement in a single pass and thus provides notable benefits regarding processing efficiency and energy consumption. The Vo-CAP die design consists of three sequential zones: a vortex-extrusion zone that induces rotational shear and contributes to a more homogeneous structure, a transition channel for stabilizing the flow, and a 120° ECAP zone for classical deformation. The process deformation behavior in all three zones was analyzed through combined experimental and numerical approaches, and the corresponding processing parameters were optimized using FEA, ANN, and NSGA-II-based multi-objective algorithms. Microstructural characterization was performed using optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). These analyses revealed significant grain refinement, subgrain formation through continuous dynamic recrystallization, and the redistribution of strengthening precipitates (MgZn₂ and Al₂CuMg phases). The microstructural evolution indicated enhanced grain-boundary strengthening and precipitation strengthening mechanisms. To validate the improvements suggested by the microstructural observations, mechanical testing was subsequently performed. The results indicated that single-pass Vo-CAP processing produced substantial mechanical enhancement, with yield strength improving by 305% to reach approximately 585&#xa0;MPa, ultimate tensile strength increasing by 122% to about 644&#xa0;MPa, and microhardness showing a substantial rise to around 203 HV. Material toughness also improved, with only a moderate reduction in ductility. Taken together, these findings show that Vo-CAP achieves the mechanical properties normally attainable only through multi-pass ECAP but does so in a single processing pass, significantly reducing processing time and energy consumption. Consequently, this study demonstrates the potential of Vo-CAP as an efficient and commercially viable SPD technique for producing ultrafine-grained, high-strength materials, offering substantial advantages for large-scale industrial applications in the aerospace, automotive, and defense sectors.</p>

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Mechanical enhancement of AA7075 via vortex extrusion–ECAP (Vo-CAP) as a single-pass hybrid severe plastic deformation technique

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月7日

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  • Hüseyin Beytüt,
  • Kerim Özbeyaz,
  • Şemsettin Temiz,
  • Ömer Karabey

摘要

This experimental study evaluates the applicability and effectiveness of Vortex Extrusion–Equal Channel Angular Pressing (Vo-CAP), a hybrid severe plastic deformation method, in processing AA7075 aluminum alloy. Unlike conventional multi-pass SPD techniques that require multiple processing cycles to obtain significant property improvements, Vo-CAP achieves superior mechanical property enhancement in a single pass and thus provides notable benefits regarding processing efficiency and energy consumption. The Vo-CAP die design consists of three sequential zones: a vortex-extrusion zone that induces rotational shear and contributes to a more homogeneous structure, a transition channel for stabilizing the flow, and a 120° ECAP zone for classical deformation. The process deformation behavior in all three zones was analyzed through combined experimental and numerical approaches, and the corresponding processing parameters were optimized using FEA, ANN, and NSGA-II-based multi-objective algorithms. Microstructural characterization was performed using optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). These analyses revealed significant grain refinement, subgrain formation through continuous dynamic recrystallization, and the redistribution of strengthening precipitates (MgZn₂ and Al₂CuMg phases). The microstructural evolution indicated enhanced grain-boundary strengthening and precipitation strengthening mechanisms. To validate the improvements suggested by the microstructural observations, mechanical testing was subsequently performed. The results indicated that single-pass Vo-CAP processing produced substantial mechanical enhancement, with yield strength improving by 305% to reach approximately 585 MPa, ultimate tensile strength increasing by 122% to about 644 MPa, and microhardness showing a substantial rise to around 203 HV. Material toughness also improved, with only a moderate reduction in ductility. Taken together, these findings show that Vo-CAP achieves the mechanical properties normally attainable only through multi-pass ECAP but does so in a single processing pass, significantly reducing processing time and energy consumption. Consequently, this study demonstrates the potential of Vo-CAP as an efficient and commercially viable SPD technique for producing ultrafine-grained, high-strength materials, offering substantial advantages for large-scale industrial applications in the aerospace, automotive, and defense sectors.