Discussion and Analysis of Cast Aluminum Technology

Aluminum has low density, high plasticity, excellent electrical and thermal properties, dense oxide film protection on the surface, and good corrosion resistance. The reserves of aluminum in the earth's crust are large. According to statistics, iron in the earth's crust accounts for 4.7% (mass fraction, the same below) and aluminum accounts for 7.5%. At present, aluminum has become a relatively large amount of metal in non-ferrous metals.

Cast aluminum alloys are based on pure aluminum with the addition of other metals or non-metallic elements, which not only maintain the basic properties of pure aluminum, but also have a good overall performance due to alloying and heat treatment. Aluminum and aluminum alloys occupy an important position in the industry, and are used in a large number of fields such as military, industry, agriculture, and transportation, and are also widely used as building structural materials, household life appliances, sporting goods, and the like.

In such alloys, Si is the main alloying element, and Si improves the fluidity of the alloy, reduces hot cracking tendency, reduces porosity, and improves airtightness. These alloys have good corrosion resistance and moderate machining performance, moderate strength and hardness, but low plasticity. According to the Si content in the alloy, the alloys can be divided into eutectic Al-Si alloys (ZL102, YL102, ZL108, YL108 and ZL109), hypereutectic Al-Si alloys (ZL1l7 and YL1117) and hypoeutectic aluminum-silicon alloys ( The rest of the alloy).

ZLI02 is a typical binary eutectic Al-Si alloy. The mass fraction of Si in the alloy is 10%-13%. This alloy has excellent casting properties, but mechanical properties and cutting performance are poor. In order to improve the room temperature and high temperature mechanical properties of the ZL102 alloy, a certain amount of Mg, Cu and Mn are added to make the ZL108 alloy, so that the coefficient of thermal expansion is small, and the wear resistance is improved. ZL109 is also a eutectic aluminum-silicon alloy. Compared with ZL108 alloy, the Cu content is reduced, Mg content is increased, and Ni is used instead of Mn. The alloy has better heat resistance. The ZL108 and ZL109 alloys are widely used as pistons for internal combustion engines. YL102 and YL108 are mainly used as die casting alloys.

Al-Si-Mg alloys in hypoeutectic Al-Si alloys include ZL101, ZL101 A, ZL104, YL104, ZL114A, ZLl15, and ZL1l6. The main differences in the composition of these alloys are: ZL104 alloy added Mn, ZL115 alloy added Zn and he, ZL1l6 alloy added Ti and Be, ZL101A and ZL114A alloy is made of high purity refined aluminum as raw material, reducing the impurity content . These alloys have good casting properties, moderate mechanical properties and good corrosion resistance and are widely used in industry. The alloys belonging to the Al-Si-Cu system include ZL105, ZL105A, ZL106, ZL11O, ZL111, ZL107, YL112 and YL113. The first five alloys contain Mg, the latter three alloys do not have Mg, but the Cu content is high. In addition, a small amount of Mn and TicZL110 alloys with high Cu content and low Mg content were added to the ZLI06 and ZL111 alloys. Al-Si-Cu alloys have good casting properties, moderate mechanical properties, and poor corrosion resistance compared with Al-Si-Mg alloys. YL112 and YL113 alloys are mainly used as die casting alloys, and other alloys are used for sand casting, Metal casting and precision casting.

The mass fraction of Si in hypereutectic Al-Si alloys generally exceeds 15%. The mass fraction of Si in the United States 390. 0 alloy, German KS281 alloy and Chinese YL 117 alloy is about 18%; the mass fraction of Si in China's ZL117 alloy and Germany's KS280 alloy is about 21%; in Germany's KS282 alloy. The mass fraction of Si is about 24%. With the increase of Si content, these alloys have reduced density, reduced coefficient of thermal expansion, increased hardness, wear resistance, and volume stability. They are mainly used as piston materials. Their main drawbacks are that they are difficult to machine and require strict tools.