Abstract: An apparatus of adding high vapor pressure magnesium to a steel liquid, includes a magnesium additive device and a tube furnace. The magnesium additive device includes a storage barrel, a conveying pipe, a control valve, and an insertion tube. A method of adding high vapor pressure magnesium to a steel liquid, includes placing the magnesium additive device in the tube furnace, and delivering pure magnesium particles into the storage barrel. When the temperature at the mediate lower position of the conveying pipe is increased to reach a preset value, the control valve is opened to pour the pure magnesium particles into the conveying pipe to form a magnesium vapor, and an argon regulating valve is opened to introduce the argon into the conveying pipe so as to add the magnesium vapor to a steel liquid by carrying of the argon.

Abstract: An apparatus of adding high vapor pressure magnesium to a steel liquid, includes a magnesium additive device and a tube furnace. The magnesium additive device includes a storage barrel, a conveying pipe, a control valve, and an insertion tube. A method of adding high vapor pressure magnesium to a steel liquid, includes placing the magnesium additive device in the tube furnace, and delivering pure magnesium particles into the storage barrel. When the temperature at the mediate lower position of the conveying pipe is increased to reach a preset value, the control valve is opened to pour the pure magnesium particles into the conveying pipe to form a magnesium vapor, and an argon regulating valve is opened to introduce the argon into the conveying pipe so as to add the magnesium vapor to a steel liquid by carrying of the argon.

Abstract: A metallurgical method for refining grains of steel includes adding aluminum into molten steel obtained from a secondary refining process. Aluminum reacts with oxygen and sulfur in the molten steel to reduce the total oxygen content in the molten steel to 15-120 ppm, to reduce a sulfur content in the molten steel to 15-150 ppm, and to produce aluminum oxide, obtaining cleaner molten steel. Magnesium is added into the cleaner molten steel and reacts with oxygen, sulfur, and aluminum oxide in the cleaner molten steel to reduce the total oxygen content in the molten steel to 10-60 ppm, to reduce the sulfur content in the molten steel to 5-100 ppm, and to produce inclusions including magnesium oxide, magnesium sulfide, and magnesium-aluminum spinel. Precipitates of the inclusions can serve as crystalline cores in a subsequent crystallization process to obtain fine-grained steel.