The effects of different Si content

including 1.0%

1.1%.1.3%.and 1.5%

on hot crack and mechanical properties as well as microstructure of 6082 alloy have been investigated

in which the microstructures of the alloys have been observed by OM（optical microscope）and SEM（scanning electron microscope）.The results reveal that the eutectic phase in grain boundary of the alloys with decreasing in hot crack tendency is increased with increasing in Si content.Meanwhile

the hardness and tensile strength of alloy with the reduction of elongation are increased.