The components optimized design and performance analysis of Al-Si-Mg based alloy were investigated systematically by the orthogonal experimental design of the four factors to three levels

combined with the JMat-Pro material simulation software.The results show that the Si element has the strongest role for the cooling rate of Al-Si-Mg based alloy during the solidification process

followed by the Fe element and Ti element

whereas the Mg element exhibits the minimal impact.Mg has the most obvious effect on the yield strength

tensile strength and hardness（HRC）of Al-Si-Mg based alloy

followed by Fe element and Ti element

Si element.The tensile strength of the alloy is increased to 337.2MPa from175.2MPa with the SDAS of the Al-Si-Mg based alloy decreased from 200μm to 20μm

where the Mg element is dominant role in the SDAS

followed by the Si element

Fe element and Ti element.After three step solid solution and the two step aging heat treatment

the average tensile strength

yield strength and elongation of Al-6.5Si-0.7Mg-0.2Fe-0.2Ti-0.1Zn-0.1Mn-0.1Cu alloy reach 371 MPa

310MPa and 5.84%

respectively

which is near to the calculation of JMat-Pro software.The structure of Si phase in the alloy at as-cast state exhibits plate-like or needle

while the morphology is converted into spheroidization ones gradually after heat treatment

and the fracture morphology is characterized by the dimple fracture.