T6处理对半固态压铸Al-27Si合金组织与性能的影响

Effects of T6 Treatment on the Mechanical Properties and Microstructure of Rheo-die Casting Al-27Si Alloy

采用纯铜质蛇形通道复合Sr变质制备了Al-27Si-4.5Cu-0.6Mg合金的半固态浆料,并进行了压铸,研究了在不同Sr加入量时,T6处理对流变压铸试样的性能和组织的影响。结果表明,复合工艺充分细化了初生Si和有效变质了共晶Si,再经T6处理后可以得到圆整的颗粒状共晶Si和棱角被钝化的初生Si,并且热处理前的变质效果越好,T6处理后得到的共晶Si形貌越圆整细小。T6处理进一步提高了复合处理制备的Al-27Si-4.5Cu-0.6Mg合金半固态流变压铸试样的抗拉强度,热处理前后的最高抗拉强度都出现在Sr含量为0.02%条件下,分别为228.8 MPa和254.7 MPa。

The semi-solid slurry of Al-27Si-4.5Cu-0.6Mg alloy was prepared by a composite process of serpentine pouring channel(SPC)and Sr-modifier.The rheological die-casting was carried out.The effects of heat treatment on the properties and microstructure of the rheological die-casting samples with different Sr addition were investigated.The results show that primary Si and modified eutectic Si are fully refined by the composite process,and the rounded granular eutectic Si and primary Si with edges and angles passivated can be obtained after T6 treatment.The better the modification effect before heat treatment,the more rounded and finer the morphology of the obtained eutectic Si after heat treatment.Heat treatment further improves the tensile strength of semi-solid rheological die-casting samples of Al-27Si-4.5Cu-0.6Mg alloy prepared by composite treatment,and the maximum tensile strength appears at the condition of 0.02%Sr content before and after heat treatment,which are 228.8 MPa and 254.7 MPa,respectively.