| 摘要 |
PROBLEM TO BE SOLVED: To provide a metallurgical method for refining crystal grains in steel, with which the cleanliness of molten steel is made high, the number of fine crystal nucleus in the molten steel is increased, micronizing crystal grains in steel is promoted, and further, the strength and toughness of the steel are made high.SOLUTION: Aluminum is added into the molten steel and aluminum oxide is generated by reacting the aluminum with oxygen and sulfur in the molten steel until resulting in 15-120 ppm of the total oxygen content in the molten steel and 15-150 ppm of the sulfur content to obtain cleaner molten steel liquid. Successively, magnesium is further added into the cleaner molten steel liquid and thereby, the magnesium is reacted with the remaining oxygen, sulfur and aluminum oxide (AlO) in the cleaner molten steel liquid until resulting in 10-60 ppm of the total oxygen content and 5-100 ppm of the sulfur content in the molten steel liquid, and magnesium oxide, magnesium sulfide and magnesium aluminum spinel as inclusions are generated to produce fine granular steel with the precipitated inclusions as the crystal nucleus in the solidifying process of the molten steel liquid. |
