A356.2 alloy semi-solid billets were prepared by near liquidus pouring combining with equal channel angular extrusion and semi-solid isothermal treatment. Equivalent spherical diameter and shape factor of the semi-solid billets were measured by metallographic microscope and metallographic analysis system. The results reveal that A356.2 alloy semi-solid billets with desirable properties in which average grain size is in range of 60

9

0 μm and shape factor is in range of 0.7

0

.9 can be successfully prepared by the composite technology. Semi-solid billets with fine rosette and lumpy grain can be obtained by near liquidus pouring

and grain accumulate severe energy of deformation through severely distortion and breaking during ECAE process

which results in the gradual transformation of grain into near-spherical and spherical structure with the increase of grain size.