The rheological die forging forming of A356 semi-solid slurry which was treated by self-developed power ultrasonic double-sound field apparatus was performed on the YB32-200 four pillars hydraulic machinery to understand microstructure and mechanical properties of the parts formed after and before T6 treatment at 625

615

605℃.The results show that the α-Al+Si eutectic phase is dissolved into primary α-Al phase

and fine Mg2Si dispersoids are generated in the alloy parts during ageing process.Tensile strength and elongation are improved

where the tensile strength reaches 241.20MPa at 615℃

and the elongation rate reaches 17.88% at 605℃.