Thermal insulation performance of continuous casting moulding slag

Continuous casting moulding slag must have good thermal insulation properties, which can inhibit the formation of bridges and floating bodies in the mould during the continuous casting process. At the same time, it can increase the meniscus temperature, maintain the slag flow channel, reduce the oscillating marks, and reduce surface and subsurface defects. (such as pinholes) lh Especially in the production process of ultra-low carbon steel continuous casting, in order to avoid the surface carburization of the casting and the carbon steel in the crystallizer, the carbon content of the continuous casting mold slag is greatly reduced and the carbon content is reduced. It is still necessary to ensure that the continuous casting mold slag has a certain degree of thermal insulation properties. The measure is to use light continuous casting mold slag and ensure that the thickness of the powder slag layer is sufficiently large defeltH, etc. It is found that the thermal insulation performance of continuous casting mold slag is affected by the sintering speed and melting speed. influences. Nakado et al. krnet Carbonaceous material Microparticle type density Grain size Specific surface area m2.g - Ignition point Purity amount Carbon black Black powder Amorphous structure Graphite gray Black flake Hexagonal structure Active carbon Black gray powder Amorphous structure Temperature rise and fall at the bottom of the graphite crucible at the bottom of 5mm is controlled by a microcomputer program, with a temperature accuracy of ±0.5°C. High-purity graphite crucibles containing slag are internal diameters of 60mm, and high-80mm graphite crucibles are lined with molybdenum sheets to prevent graphite contamination from continuous casting protection. Slag, affecting insulation and thermal insulation performance Three PtRh30-Pt type thermocouples are distributed on the centerline of the graphite crucible at an even distance. The vertical distance between the three temperature measuring points is 10mm1.3. The composition is different, but the experimental results still show that the shape of the slag particles of the mold casting slag has a significant effect on its thermal insulation performance. AJFV (a) and melting rate (b) of the four kinds of low carbon steel continuous casting slag used in the AHif VCD slag It can be seen from Table 2 that the powdered slag and hollow spherical slag have good thermal insulation properties, followed by spherical granule slag and columnar granule slag. According to the heat transfer theory of the packed bed, the heat transfer performance of the slag layer is related to the particle size, voidage, and density of the continuous casting mold flux. The voids of the powdered slag are small and dispersed, and the convective heat transfer in the slag layer is relatively weak, so the thermal insulation performance is better. Hollow spherical slag can improve the thermal insulation performance by reducing the density of continuous casting mold powder. This is consistent with the research results of Nakato et al. 21 that the gap between columnar granules is large and continuous, and the convective heat transfer in the slag layer is relatively strong. Thermal insulation performance is the worst.

In this experiment, the influence of the shape of the slag particles of the continuous casting mold slag on the thermal insulation performance is not completely consistent with that on the melting speed. This is mainly due to the fact that the shape of the slag grains of the continuous casting mold slag is not considered when the melting rate is measured. The effect of melting speed.

For ultra-low carbon steel continuous casting mold slag, in order to suppress carburization on the surface of cast billet and carbon steel in the mold, the amount of carbon in the slag must be reduced. In this case, the use of hollow spherical slag can suppress ultra-low carbon steel. Carbon insulation of slabs while ensuring the thermal insulation properties of continuous casting mould slag Table 2 Slag shape and chemical composition of four types of low carbon steel continuous casting mould slag used on site slag type slag particle shape - chemical composition/% powder slag hollow sphere Slag spherical granule slag columnar granule slag 3 Conclusion A comprehensive evaluation index JRBW describing the adiabatic insulation performance of continuous casting mold powder has been proposed. The physical meaning can be defined as the temperature difference in the slag layer per unit length per unit time as the carbon content increases. , JRBW gradually increased, continuous casting mold flux insulation performance gradually improved.

The influence of the type and content of carbonaceous materials on the adiabatic and thermal insulating properties of continuous casting mould dregs has a certain similarity with that on the melting rate. The influence of the shape of the slag particles on the thermal insulation performance of continuous casting moulding slag is significant. The spherical slag has good thermal insulation properties, followed by spherical granules and columnar granules.