Overheating of copper mold tube meniscus in billet crystallizer
This situation is common in many copper tube production bases for small square billets, and if it persists, it’s not normal. In short, the temperature in the meniscus region is too high. What causes this? There are many influencing factors; otherwise, why would the crystallizer be considered the heart of continuous casting?
For example, the crystallizer’s operating water temperature, cooling flow rate and pressure, water quality, uniformity of the water gap, high casting speed, excessively high number of furnace runs using the copper tube, insufficient protective slag addition resulting in a thin slag layer, and the copper tube’s material and plating type all have an impact.
Of course, these aren’t all the core factors causing this overheating. Excluding stable factors like the copper tube material, we can verify other factors such as water temperature and quality, protective slag addition, and service life, especially the protective slag. Personally, I believe that the blackening on the four sides of the copper tube suggests a thin protective slag layer in the crystallizer. The intense heat transfer from the high-temperature molten steel causes uneven heating on different sides. Meanwhile, due to the inconsistent heat flux density on each side, the billet shell grows unevenly, the air gap between the billet shell and the copper tube of the crystallizer increases, heat transfer is hindered and in an unstable state. Once stress is concentrated, there is a risk of cracks and leakage when the billet exits the crystallizer.
