Influence of Zn

Mg and Cu elements on mechanical properties and hot cracking tendencies of cast Al-Zn-Mg-Cu alloys were investigated by using orthogonal experiment method.The results show that the influence of three elements on the tensile strength and hot cracking tendency of alloys is distinct.The influencing sequence on the tensile strength is as follows:Zn>Mg>Cu

while the order of affecting hot cracking tendency is Cu=Mg>Zn.In the experiment range

tensile strength and hot crack tendency are increased with increasing in Zn content

and decreased with increasing in Cu content

respectively.However

with Mg content increases

tensile strength shows firstly increased and then decreased

while hot crack tendency shows firstly decreased and then increased.The eutectic phase with low melting point and along the grain boundary has important effect on tensile strength and hot cracking

where with the eutectic number increases

tensile strength is decreased

and hot tearing tendency is firstly reduced and then increased.