| Mold is the key processing tool in plastic forming. The properties and service life of the plastic forming mold are determined by the material of the mold. It determines the quality of plastic products. Cast Al-Zn alloy have good casting properties and high mechanical properties, it is suitable for the manufacture of plastic mold. However, currently, it is lack of systematic and in-depth study on Cast Al-Zn alloy as plastic mold material at home and abroad.This paper focuses on the microstructure and mechanical properties of cast Al-Zn alloy as plastic mold material. Including,effect of alloying elements, modification, cooling conditions and pouring temperature on microstructure and properties of Al-Zn alloy. The main research conclusions are as follows:(1) The effects of alloying elements Zn, Si and Mg on microstructure and hardness of An-Zn-Si-Mg based alloy were studied. The result showed that a(Al) in the microstructure of the alloy is gradually increased. Brinell hardness and the microhardness of a-phase of the alloy are gradually improved. Brinell hardness of the alloy is increased by8.75%. Microhardness of a-phase in the alloy is increased by5.2%when zinc content is increased from9%to13%. Eutectic silicon gradually in the microstructure is increased and Brinell hardness of the alloy is inproved by6.33%when silicon content is increased from6%to8%. When the content of magnesium is increased from0.1%to0.3%, the microstructure of the alloy did not change significantly, but the brinell hardness value is increased3.75%and the microhardness of a-phase is increased by3.2%.(2) The effects of alloying elements Zn on microstructure and hardness of An-Zn-Mg based alloy were studied. The result showed that a(Al) in the microstructure of the alloy is gradually increased, brinell hardness and the microhardness of a-phase of the alloy are gradually improved. Brinell hardness of the alloy is increased by26%and microhardness of the a-phase is increased by27.7%when zinc content is from5%to6.5%.(3) The effects of the modification whit the Al-Ti alloy and the La-Ce mixed rare earth on microstructure and brinell hardness of Al-12Zn-7Si-0.2Mg alloy were studied. The result showed that the microstructure of alloy could be refined by Ti and La-Ce rare earth by adding amount of Ti from0to0.3%and amount of La-Ce mixed rare earth from0.8to1.4%. Comparing with no modification, the hardness of alloy is increased by3.7%when addition of0.2%Ti. The microstructure of alloy could be refined and the hardness of alloy is increased by4.9%when an amount of La-Ce mixed rare earth is added.(4) The effects of the cooling conditions and pouring temperature on microstructure and brinell hardness of Al-12Zn-7Si-0.2Mg alloy were studied. The result showed that the microstructure of alloy is refined and uniform, when alloy melt was poured in metal mold, the hardness of alloy is increased by3.8%, comparing with pouring in graphite mold. The microstructure of alloy is trefined and uniform, when alloy melt was poured at700℃, the hardness of alloy is also increased by7.3%, comparing with the alloy melt was poured at780℃. |
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