Experimental setup of pressure transfer law in squeeze casting process

In the process of squeeze casting experiment, the material of the casting is aluminum alloy and magnesium alloy. The shape and size of the casting and the installation of the measuring unit are shown in Figure 1. Among them, point a is the center position of the top surface of the casting, and point B is the top angle position of the top surface of the plate mold casting. The alloy composition and thermophysical properties of related materials involved in this study are shown in Table 2. Other experimental settings and processes are implemented according to the experimental methods.

In the study, working conditions 1, 2 and 3 represent three working conditions with applied pressure of 70, 46 and 23 MPa. Three to four experiments were carried out under each condition. The initial mold temperature of aluminum alloy in working condition 1 is 230 ℃, and that of other working conditions is 250 ℃; the pouring temperature of three working conditions is 660 ℃. In this chapter, the squeeze casting experiments of aluminum alloy and magnesium alloy under the above three working conditions are carried out, and the quantitative data of interface heat transfer coefficient and interface pressure are obtained.

(a) Casting top (b) B-B section

In the study, the heat transfer coefficient and pressure of the interface were obtained by squeeze casting experiment, as shown in Fig. 2 and 3. As shown in Fig. 2, when the high temperature melt is poured into the mold cavity, the interface heat transfer coefficient rises sharply to the peak value, and then it begins to decrease gradually after reaching the peak value. This is due to the close contact between the high temperature melt and the mold wall. As the solidification proceeds, the contact gradually deteriorates due to the influence of solidification shrinkage, and the heat transfer coefficient begins to decrease gradually. As shown in Fig. 2 and Fig. 3, the interfacial heat transfer coefficient increases sharply to the peak value and the interfacial pressure increases almost at the same time

Add to the peak. This shows that the interface contact is closer under the action of external pressure. As shown in Figure 3, the interface pressure begins to decrease after reaching the peak value, and the interface heat transfer coefficient also begins to decrease after reaching the peak value, which decreases rapidly in the initial stage, and then gradually slows down. The reason is that with the decrease of interface pressure, the interface contact deteriorates more seriously at the initial stage, and then the deterioration gradually slows down.

As shown in Fig. 2, although there are some similarities in the variation of the interfacial heat transfer coefficient between aluminum alloy and magnesium alloy, the differences are also very obvious. For aluminum alloy, the interfacial heat transfer coefficient remains unchanged when it decreases to 6.6 kwm-2k-1. However, for magnesium alloy, the interfacial heat transfer coefficient fluctuates around 6 kwm-2k-1, and the fluctuation is large. This is mainly due to the large fluctuation of interfacial heat transfer coefficient caused by the reaction between magnesium and oxygen on the surface of the casting after the high temperature magnesium alloy melt is poured into the mold and contacts with air. The results show that the interface heat transfer coefficient reaches the peak quickly after the applied pressure. The peak value of interfacial heat transfer coefficient of magnesium alloy is about half of that of aluminum alloy. The change trend of interface heat transfer coefficient of aluminum alloy in condition 2 and 3 is similar to that of magnesium alloy in condition 1 and 2. It can be seen from Figure 3 that the values and acting time of interface pressure of aluminum alloy in condition 2 and condition 3 are similar to those of magnesium alloy in condition 1 and condition 2, and the difference between the interface pressure of aluminum alloy in condition 2 and condition 3 is larger than that of magnesium alloy in condition 1 and condition 2. These trends are also reflected in the change trend of interface heat transfer coefficient. In addition, the interface heat transfer coefficient of magnesium alloy in condition 1 and condition 2 decreases sharply at 19S. Because of the large interface pressure and action time, the change of interface heat transfer coefficient of aluminum alloy in condition 1 is quite different from that of other working conditions, and the influence of interface pressure is particularly significant.

The heat transfer coefficient and pressure of the interface between aluminum alloy and magnesium alloy obtained by the experiment can be used to establish the heat transfer coefficient model of aluminum alloy and magnesium alloy according to the proposed modeling method. The model can be applied to the numerical simulation to provide accurate boundary conditions for the numerical simulation.

Scroll to Top