Global Casting News

Compostion of die casting aluminum


Die casting aluminum features low density,good heat conductive property,corrosion resistance,while it has disadvantages,such as sticking to the cavity.Therefore,it is important to understand the properties of die casting aluminum.There are two methods that can improve die casting aluminum property.One is to improve die casting processing,the other is to improve composition of die casting aluminum.Most of die casting process are fully developed and hard to improve.Therefore,to adjust composition of die casting aluminum is useful way to improve die casting aluminum property.By composition,the die casting aluminum categories are divided into Al-Si,Al-Mg,Al-Si-Mg and Al-Si-Cu.By add Cu,Fe,Sr,Zr,Mn,Ti,the die casting aluminum property can be improve dramatically.

The pure aluminum can only be used into cables,heat exchange system and capacitors since there is no high requirement for low load,low corrosion resistance and electric conduct in these field.By compare to pure aluminum,aluminum alloy can be widely used in many field.By adding certain elements into aluminum alloy,the castability and mechanical property can be improve very much.

Si is main element in die casting aluminum.The strength of die casting aluminum enhanced when composition of Si is lower,while strength decreased when composition of Si goes higher.Few amount of Si can improve fluidity of alloy.The fluidity affected badly when there is over amount of Si in alloy.Therefore,the fluidity of alloy can be improved by adding about 12.5% Si into Al-Mg alloy.

Mg can improve tensile strength,hardness and corrosion resistance of die casting aluminum.By research,the corrosion resistance and mechanical property can be improved by adding small amount of Mg into alloy.While the alloy is easy to crack if add too much Mg into alloy.The following chart show the performance of alloy with different amount of Mg.



Tensile Strength(Mpa)

Yield Strength


















Cu can improve hardness,strength and heat resistance of die casting aluminum.When composition of Cu goes to 4.5%-5.5%,the aluminum alloy is suitable to heat treatment,while the aluminum alloy tend to crack when composition of CU is more than 5.5%.Also,the effect of heat treatment is weak when composition of Cu is over amount.

The elongation of die casting aluminum does not change when alloy contain 0.6%-0.8% Fe.However,elongation lower very much when composition of Fe is more than 1.0%.If composition of Fe is more than 1.0%,the castings will be hard for machining.Therefore,it is necessary to keep Fe within 0.8% in order to get good performance of die casting aluminum.

In addition,Sr can improve mechanical and machining property.The roughness of surface can be improved by add small amount of Sr into die casting aluminum.Zr is good for strength and corrosion resistance of die casting aluminum.Mn and Ti are also helpful to improve the strength and mechanical property of die casting aluminum.

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