Transient heat flux coefficient of directional solidification interface in Squeeze Casting

In addition to the research on the interface heat transfer between casting and mold (die) in sand mold, metal mold, directional solidification, investment casting, die casting and other casting processes, there are also many researches on the interface heat transfer in thin strip continuous casting, twin roll casting and other processes, which are characterized by very short solidification time. However, due to the need of technology development and the progress of measurement technology, researchers also pay attention to the research in this area. According to the devices used in the experiment, these works are divided into on-line measurement and physical simulation.

On line measurement is to obtain the corresponding interface heat flux data by directly measuring the temperature change of the crystallizing roll or strip. Tavares et al. Systematically studied the variation of interfacial heat flux between strip and copper roll during the forming process of carbon steel strip by arranging thermocouples in copper roll of experimental twin roll strip caster. Pedro et al. Designed a device to directly measure the transient heat flux of aluminum strip in horizontal continuous casting process. The device is mainly composed of a cylinder body containing high temperature liquid metal and a base which can move at a certain speed. The thermocouple is embedded in the base, and the heat flux on the base surface can be obtained by inverse algorithm. They also systematically studied the effects of various factors such as strip thickness, coating, superheat, substrate velocity and roughness on the substrate surface heat flux.

Physical simulation is to abstract the solidification process of strip continuous casting and twin roll casting, and develop different types of physical simulation devices to simulate the interface of strip continuous casting and twin roll casting

Methods of heat transfer research. Among them, t. loulou et al. Used Pb, Sn and Zn as solidification materials to study the transient heat transfer of high temperature metal droplets during chilling on nickel substrate. They drop molten metal on the surface of the metal matrix, measure the internal temperature distribution of the matrix through the thermocouple embedded in the matrix, and use the measured temperature change curve and Beck’s method The effects of melt temperature, substrate surface roughness, surface lubricant and melt material composition on the surface heat flux are also systematically studied. Strezov et al. Designed a set of corresponding simulation device system according to the heat transfer characteristics of liquid steel in the early solidification stage of strip continuous casting, and used the device to study the transient heat transfer characteristics of the interface between stainless steel and copper roll. By simulating the heat transfer environment similar to the initial solidification stage of stainless steel liquid in strip continuous casting, the device has important guiding significance for the actual strip continuous casting.

Wang A method to accurately measure the transient heat flux was designed, that is, the metal as solidified material was melted by suspension melting device, and then dropped on the inclined metal substrate. The dripping metal melt flowed on the metal substrate and solidified rapidly. An infrared thermometer was set above the solidified metal strip to record the temperature change on the surface of the melt in real time, and the non-linear method was used By using this device, the interface heat transfer coefficient of liquid contact and solid contact can be obtained respectively. Wang also systematically studied the interface heat transfer of several different metals such as Cu and Ni when they drop on different metal substrates, and focused on the influence of melt superheat and substrate surface roughness on the interface heat transfer.

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