Numerical Simulation Of Solidification Of Large-sized Alloy Prepared By Aluminum Thermal Reduction-Slag Refining Method

Cu-Cr alloy with high strength, hardness, good electrical and thermal conductivity, is one of the most commonly used materials for vacuum switch contact. This paper proposed a new preparation process of large size of Cu-Cr alloy ingot based on Aluminum thermal reduction-slag refining method. The process has the advantages of simple process and low cost. But the Cu-Cr alloy is immiscible alloy and is prone to segregation in the solidification process. Using finite element analysis software ANSYS, this paper analyzed thermal field of casting solidification process, studied the influence of different cooling methods, different mold sizes and different types of mold slag on the temperature field and provided a theoretical basis for selecting the technological parameters in the rapid solidification process of Cu-Cr alloy. The conclusions are as follows:The cooling speed of natural cooling, cooling water jacket and direct water cooling increase gradually, the average values were respectively2.8K/s,10K/s,42.5K/s. The rate of cooling water jacket and direct water cooling is large and cooling intensity is high, which can be used in cooling process.With the increasing slag addition, high temperature zone gradually shift from the center to the above axis side. The thermal conductivity of the slag has a certain influence on the cooling rate of alloy. The slag of large thermal conductivity transfers more heat in the cooling process, thus the cooling rate of the alloy will slow down. However, the larger mold inner diameter, the smaller impact of the slag on the cooling performance. Therefore, refining slag with lower thermal conductivity and smaller slag thickness is more conducive to the rapid solidification of alloys.The cooling rate of the alloy decreases with the increase of mold diameter. With the increasing cooling intensity, the influence of the mold diameter is reduced gradually. Because the heat conducting ability of the CuCr25alloy is stronger, the cooling rate is higher than that of CuCr50alloy. When producing CuCr50alloy ingots or the large-sized alloy ingots, the cooling intensity should be increased as much as possible.The theoretical calculation of floating distances of chromium particles of different sizes varies with the changing coagulation times were carried out. Combined with the solidification time under different conditions obtained by numerical simulation, this paper found that when cooling water jacket and direct water cooling, the floating distance of chromium particles is small, and when the natural cooling, the floating distance of chromium particles is larger, which can produce apparent gravity segregation.