Smelting method of ultralow-oxygen and medium-high-carbon steel

Abstract

The invention provides a smelting method of ultralow-oxygen and medium-high-carbon steel. Molten iron is pretreated until [S] is smaller than or equal to 0.003%, and special low-sulfur waste steel is matched. [C] at the end point of a converter is controlled between 0.1% and 0.2%, the [S] at the end point is smaller than or equal to 0.01%, carbon powder is adopted before tapping and in a tapping process for primary deoxidization, the carbon powder added before tapping accounts for 50-65% of the total quantity, and the carbon powder accounting for 35-50% of the total quantity is added after tapping is started for 2-4 minutes. The molten iron which is treated by primary deoxidization is lifted into a ladle furnace and is heated, and at the same time, part of refining slags is added. The total slag quantity is controlled at 12-15kg per ton of steel. Then, after the molten iron is lifted into a RH furnace and kept at the condition that the vacuum degree is smaller than or equal to 70pa for 6-7 minutes, aluminum pellets are added according to 0.6-0.8kg per ton of steel, and vacuum is kept for another 3 to 5 minutes; and finally, vacuum alloying is carried out, vacuum is kept for another 5-6 minutes. The molten iron treated by the RH furnace is lifted into the ladle furnace again, and at the same time, deoxidization is carried out by using aluminum pellets for making white slags. Finally, after pure calcium lines are fed according to 1.0-1.2m per ton of steel to carry out inclusion denaturating treatment, and soft blowing is carried out for 20-25 minutes, tapping and continuous casting pouring are sequentially carried out.

Description

technical field [0001] The invention belongs to the new technology of steelmaking, and in particular relates to a method for smelting ultra-low oxygen medium-high carbon steel. Background technique [0002] At present, there are basically two smelting methods for smelting ultra-low oxygen steel or even ultra-low oxygen medium-high steel in the world: the first method is to add a large amount of aluminum-based deoxidizer during the tapping process of the converter, and to produce high-alkalinity refining slag twice in the ladle furnace, and then Vacuum treatment, then calcium treatment and long-term soft blowing; the second method, adding a large amount of aluminum-based deoxidizer during the converter tapping process, using two vacuum treatment processes, and adding a ladle furnace treatment process between the two vacuum treatments . The technical defects of these two methods are: aluminate-based inclusions are produced during the deoxidation process; ladle slag removal op...

AI Technical Summary

Problems solved by technology

The technical defects of these two methods are: aluminate-based inclusions are produced during the deoxidation process; ladle slag removal operation is likely to cause secondary oxidation of molten steel, and increase metal loss and temperature loss at the same time; Large consumption of slag

In addition, the above method has a long refining cycle, difficult production organization, and high production costs.

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