The
Crystallizer copper plate is made of Cu-Cr-Zr. The requirements of high-efficiency continuous casting mold are good thermal conductivity, high recrystallization temperature, high thermal fatigue resistance, good wear resistance and long service life. The main feature of the high-efficiency continuous casting mold copper plate material is that the copper plate material achieves comprehensive performance. The copper plate base of Cu-Cr-Zr material has high strength and hardness, and the recrystallization temperature is nearly 500 °C, which effectively avoids the mechanical properties of the copper plate due to recrystallization and the deformation of the copper plate. At present, the copper plating is a 0.3 mm thick Ni-Fe alloy. The Ni-Fe alloy coating has a hardness of about HV450, which is more than twice as high as that of the Ni+Cr composite coating. The wear resistance is enhanced and the service life is long, and the thickness of the coating can be appropriately thinned, so that the influence of the coating on the thermal conductivity of the copper plate is reduced. small.
The process effect of crystallizer vibration is mainly to adjust the consumption of mold flux to improve the lubrication condition of the mold, promote the healing of the shell, reduce the depth of the vibration mark and improve the surface quality of the cast billet. The Tangshan Steel 1700 medium-thin slab mold was used in the initial stage of production to produce an O-frame type vibration device. Due to the poor vibration stability of the vibrating device and the large yaw amount, the liquid level fluctuation of the crystallizer is excessively large, and the steel leakage accident frequently occurs. After the vibration device was changed to the unit type hydraulic vibration, the stability and yaw of the crystallizer vibration were significantly improved, and the fluctuation of the molten steel level in the crystallizer was effectively controlled.
When the molten steel enters the crystallizer, it will solidify and shrink. Inevitably, a certain thickness of air gap will appear between the shell and the crystallizer wall. The appearance of the air gap will greatly reduce the heat transfer effect of the crystallizer. The air gap thermal resistance accounts for the crystallizer. The total thermal resistance is about 70%. The solidification and shrinkage characteristics of steel grades are an important factor affecting the thickness of air gaps. In order to reduce and control the adverse effects of air gaps on the heat transfer of crystallizers, the size of the upper and lower mouths of crystallizers is generally designed to have a certain reverse taper according to the characteristics of steel grades. Improve the heat transfer effect of the mold. Controlling and improving the heat transfer effect of the crystallizer include two aspects, one is to improve the heat transfer efficiency in the longitudinal direction of the crystallizer, increase the thickness of the crystal shell, and on the other hand to improve the heat transfer uniformity in the transverse direction of the crystallizer, and to ensure Uniform growth of the shell within the mold.
July 11, 2022
