Microstructure and mechanical properties of permanent mold A356 aluminum alloy casting before and after hot deformation were investigated to examine the effects of hot deformation by investigating the same parts at varied deformation rate and the different ones at the same deformation rate. The results indicate that elongation of the permanent mold castings is improved as a result of effectively eliminating casting defects in microstructure and making eutectic Si particle distribute orderly by hot deformation. The elongation of the permanent mold casting is increased from 2.1% in as-cast state to 11% in hot deformed state

and at a given 20% hot deformation rate

that at different positions of the castings are increased by 6.13%

7.76% and 8.72%

respectively

compared with that of as-cast ones.