Influence of forging on the microstructure and tensile properties of Al–based vortex plate

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Abstract An AHS-2 alloy billet (~80 mm in diameter), with the composition of Al-10.13 wt.% Si-4.08 wt.% Cu-0.7 wt.% Mg-0.24 wt.% Fe, was hot forged to a vortex plate (~120 mm in diameter) product by hot die forging process (HDFP), through the back-pressure processing technology. The microstructure of both the billet and the product was investigated by optical microscope, X-ray diffraction, field emission scanning electron microscope, and electron backscatter diffraction. The main second phases in the alloy include Si, Al2Cu, Mg2Si and Al5FeSi. The phase particles were broken into smaller ones during the HDFP process, while the averaged grain size of α-Al matrix was slightly increased from 3.8 to 4.5 μm. The α-Al matrix of the billet has the texture close to <100> // ND (normal direction) and <111> // ND, while the product keeps the texture close to <100> // TeD (tensile direction) and <111> // TeD. The yield strength is increased from 142 ± 2 MPa for the billet to 430 ± 2 MPa for the product, while the ultimate tensile strength is simultaneously enhanced from 222 ± 3 MPa to 477 ± 2 MPa. The enhancement of yield strengthening is regarded mainly related to the texture difference of α-Al matrix, while the ultimate tensile strength difference has relationship with the variance of both matrix texture and size change of second phase particles. This study may be referred for material choosing and forging parameter designing in new energy automobile industries.