The status function and prospect of steel ingot

Position and function in steelmaking production:

The quantity and quality requirements of ingot are the basis of various technical and economic indexes in steelmaking. The yield of molten steel, the qualified rate of ingot, the consumption of ingot mould and refractory materials directly affect the consumption of steel materials and energy and the unit cost of steel. Ingot casting is usually the slowest and weakest link in the steel production process. In modern oxygen converters, it takes about 30 minutes to produce a single furnace of steel, while pouring and condensing a single furnace of molten steel often takes several hours. The production potential of steel making can be tapped by increasing the production capacity of ingot. Therefore, enlarging ingot shape, increasing ingot injection speed and improving ingot casting efficiency have always been the important technical measures for the existing steel mill to tap potential transformation. Ingot operation has the final and decisive effect on ingot quality. Correct and appropriate ingot casting operation may make the poor smelting quality of molten steel be remedied, and cast good ingot; At the same time, any error in casting the ingot will make the qualified molten steel cast into a certain defect or even completely scrap steel ingot. Ingot defects due to poor ingot casting, some (such as most surface defects) can be eliminated by fine cleaning; Some (such as loose, coarse grain, etc.) can be improved or alleviated in the process of thermoplastic processing; Most (such as ingot physical nonuniformity of residual porosity, crack, bubble, chemical inhomogeneity, macro and micro segregation, and nonmetallic inclusions, etc.) has to go into the finished steel, degrade the performance of the steel grade and quality, and may even become a hidden trouble, lead to serious consequences, including steel sudden failure in use. Ingot is an intermediate link connecting steel making and rolling, which is related to high yield, high quality and low consumption in steel making and rolling.

The continuous casting technology developed in the 1970s has become a new form of molten steel solidification. Due to its high metal yield, energy saving effect and convenient mechanization, automation and other outstanding advantages, in the world has been rapidly developed and popular, and gradually take the mold casting instead. In 1997, the continuous casting ratio of the world and China respectively reached 80.5% and 60.7%, but there are still 20% ~ 40% steel, still using the traditional ingot process production. Therefore, it is still of great significance to continuously update and improve ingot casting process, improve ingot efficiency, improve quality and reduce consumption for a long time in the future.

Outlook:



In the future, it is necessary to update, exploit and transform the casting technology. Around the main direction of improving quality and reducing consumption, new efforts need to be made continuously in the following areas:



(1) Promote the refining process outside the furnace in die casting steel plants to improve the cleanliness of molten steel and reduce the fluctuation range of temperature and composition of molten steel;



(2) Further improve the technical equipment of the steel barrel preparation, improve the process operation, and improve the automation level of the casting operation;



(3) Improve the design of ingot mold, continue to improve the thermal efficiency of insulation cap, improve the material and production technology of ingot mold, to further increase the yield of ingot and reduce the consumption of ingot mold;



(4) Improve the efficiency of mechanized cleaning of ingot mold, study and improve the coating of ingot mold and bottom plate, and improve the surface quality of ingot;

(5) Improve or develop a new protective pouring process to reduce or basically eliminate the secondary oxidation and inclusion pollution of molten steel in the pouring process, so as to improve the cleanliness of ingot. To realize specialization, serialization and hollow granulation of mold casting slag as soon as possible.