Effects of Si and Mg content and alloying elements on mechanical properties of A356 alloy were investigated.The results show that with increasing in Si and Mg content in a permissible range

mechanical properties of as-cast and T6 treated A356 alloy are improved to some extent

which is attributed to Si and Mg promoting the more creation of Mg2Si phase and increasing the numbers of eutectic phase.Furthermore

with adding alloying element

the mechanical properties of the alloy are greatly improved as a result of more effective refinement of primary Al phase and more full modification of eutectic Si phase.A356 alloy containing high Si and Mg element exhibits more sensitive to refinement and modification

tensile strength and elongation of T6 treated alloy reach up to 320MPa and 8.0%

respectively

increased by 18.6% and by 35.6%

respectively

compared with those of T6 treated alloy with low Si and Mg element.