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The effect ofcounter-pressure castingparameters on secondarydendrite armspacing (SDAS) of A357 alloy under different process parameters was studied. Quartz sand mould with chill can strongly decrease the SDAS. Reduced SDAS close to the mould bottom because of chilling was obtained. Pressure seems to have no apparent effect on the SDAS. In order to obtain casts with UTS ≥320 MPa, SDAS must be less than 55 μm, which means a local cooling rate VL≥0.23 ℃/s.