In order to reduce the energy consumption of automobile and the pollution of exhaust gas to the environment, the development of automobile engine shows the development trend of high efficiency and light weight. At present, most car cylinders have been produced by aluminum alloy.
Liu Wei et al. Studied the influence of Si, Cu, Mg and Mn on the mechanical properties of ADC12 Aluminum alloy. The results are shown in Figure 1. With the increase of Si content, the elongation and tensile strength of the alloy first increased and then decreased. The comprehensive mechanical properties are the best when containing 11% Si; With the increase of Cu content, the tensile strength increases significantly; With the increase of Mg content, when the Mg content reaches a certain degree, due to the formation of more mgzsi phase, and when there are more Mg2Si phase, its morphology also changes from block to strip, so as to split the matrix and damage its tensile strength, which first increases and then decreases. As can be seen from Fig. 1, with the increase of Mn content, the tensile strength of the alloy decreases, and the elongation first increases and then decreases.
The influence order of each element on the tensile strength of the alloy is Cu > mg > Si > Mn, and the influence order on the elongation is mg > Mn > Si > Cu.
Wu Bo et al. Studied the common defects of cast aluminum alloy cylinder block. The results show that leakage, loose shrinkage cavity and slag pore are the main defects of gravity cast cylinder block.
Figure 2 shows the shrinkage and looseness defect of aluminum alloy cylinder block, which mainly exists on both sides of crankshaft. By controlling the mold temperature, that is, the cooling water inlet enters from the pouring side, and by controlling the cooling water time of the bottom mold and the cooling water time of the cylinder liner block, the overall temperature gradient of the mold is improved to make the castings solidify in sequence. Since it takes 18-20 seconds to complete the mold filling of the cylinder block, and the height of the extraction block is about 1 / 2 of the cylinder block, the cylinder liner extraction block is delayed for 5 seconds after pouring, and the mold temperature can be distributed according to the gradient through the cooling of four extraction blocks. So as to improve the shrinkage defect.
Fig. 3 shows the porosity defects of aluminum alloy slag, which are mainly caused by the dead corner position during liquid aluminum filling, accompanied by slag and porosity. The improvement of such defects is mainly through improving the flow channel of molten aluminum to open up the dead corner position in the mold filling process and reduce the occurrence of such defects.
Gao Hua et al. Studied the slag inclusion of die cast Al – Si – Cu alloy automobile cylinder block, and the results are shown in Figure 4.
The energy spectrum analysis of massive inclusions is γ- Al2O3 and α- Al2O3, and carbides. Oxide inclusion is formed by the reaction between liquid metal splash and oxygen due to the high speed of die. Carbide inclusion is caused by the reaction between punch lubricating oil and aluminum alloy melt.