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        BecauseCold drawn precision tubeUnstable factors in production, casting slabs that exceed process requirements are called unstable slabs, and unstable slabs are easily scrapped. For unstable billets, we first focus on identification to reduce the occurrence of unstable billets for cold drawn precision tubes. The judgment of unsteady billet is:
1. If the black ladle, new ladle, and continuous casting tundish are not baked or the baking temperature does not meet the process requirements, the tundish will be poured with the first cast slab.
2. Due to various reasons, the molten steel level in the tundish is less than 400 mm, the liquid level fluctuates more than 5 mm, and the casting time lasts less than 3 minutes.
3. The crystallizer liquid level fluctuates greatly during low-temperature flocculation, unloading of immersed nozzles in emergencies, and processing of cast slabs produced during accidents.
4. Abnormal converter smelting heats, cast slabs with severe peroxidation of molten steel or abnormal composition, the last billet of each stream in the previous furnace and the first billet of each stream in the subsequent furnace, slab shrinkage cavities, internal cracks and other defect levels≥3. 0 billet.