Effect Of Cold Material On Temperature Field And Microstructure Of DC Casting 2024 Aluminum Alloy

The large-size aluminum alloy semi-continuous casting technology is widely used large-scale aluminum alloy forming technology.In order to obtain better quality ingots,the casting process is continuously improved.This topic is a new attempt on the basis of traditional DC casting.In the casting process,the ingot core is added with the same component round bar cold material,the cooling rate of the ingot core is increased,and a new large-size aluminum alloy casting process is developed.That is,DC casting containing a core cold material.In this paper,the physical model of traditional DC casting and DC casting with core cold material is established by using the Fluent plate in ANSYS finite element simulation software.The numerical simulation is used to analyze the temperature field in the traditional DC casting and DC casting process with core cold material.Temperature field results indicate that DC casting with core cold material smoothes the liquid pocket,but also increases the extent of the two-phase zone.Then the effects of cold material diameter and feeding speed on the temperature field were studied separately.Simulation of the temperature field change when the feeding speed is 60mm/min and the cold material diameter is 20mm and 30mm respectively and the temperature field changes with the cold material diameter is 20mm when the feeding speed is 60mm/min,150mm/min,240mm/min and 360mm/min.The influence of different insertion speeds on the DC casting temperature field containing the core cold material is obtained through numerical simulation:the fusion process of the cold material temperature field and the melt temperature field exists in the DC casting process containing the core cold material,and the faster the insertion speed The longer the fusion phase,the better the cooling effect of the cold material on the center melt,and the wider the range of the two-phase region.According to the numerical simulation results,DC casting with actual core cold material was selected for the insertion speeds of 150mm/min and 240mm/min.The macroscopic structure of the DC casting and the traditional DC casting ingot containing the core cold material was compared.Center of the section,1/4R,1/2R,3/4R and edge microstructure from the center.The experimental results show that the equiaxed grain size of the DC casting core containing the core cold material is larger than that of DC casting,the distribution range is reduced,and a large number of bright crystals appear.The columnar crystal grain size and distribution range are larger than DC casting,and the edge fine crystal.The area is not much different from DC casting,but the grain size in the segregation layer increases,increasing its thickness.