A monitoring system of tundish preheat process has been developed for the control of hydrogen content in molten steel at China Steel (CSC). The hydrogen gas accumulated inside the steel matrix may eventually induce pinholes or hydrogen-induced cracking. And the possibilities of hydrogen pick up during casting could be from the atmosphere, tundish lining, or casting powder. Our study has proved that most of the moisture comes from tundish lining. Therefore, preheated tundish was used to avoid moisture pick-up from lining at CSC. An IR-based temperature sensor has been set up to detect tundish shell temperature in this research. The temperature of tundish shell is recorded during the preheat process. It is been noticed that the temperature profile of the preheated tundish shell has a horizontal zone at 100℃. This indicates the moisture of tundish lining is evaporating at that time. When all of the moisture is out of tundish, the temperature of tundish shell will increase with preheating time until casting starts. After compared with the amount of hydrogen pickup in tundish process, the result shows that the hydrogen content in steel will decrease with the highest preheat temperature of tundish shell. When the temperature of tundish shell is higher than 120℃, the amount of hydrogen pickup in tundish is less than 1.5 ppm. Accordingly, in this study, we have built up quality indexes for the references of tundish preheat process to reduce the defects of steel product.Keywords: Tundish, preheat, monitoring, hydrogen pickup
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