Smelting process of high-carbon bearing steel

Abstract

The invention discloses a smelting process of high-carbon bearing steel. High-alkalinity refining slag with the alkalinity value of 6-9 is obtained through adding conditioned slag and a deoxidizing agent, so that relatively good desulfuration and deoxidization effects are achieved, the content of S can be reduced to about 0.002%, and the content of O can be reduced to be less than 7ppm. Meanwhile, in order to avoid brittle impurity generation caused by overhigh alkalinity of refining slag, the content Al of the molten steel is strictly controlled in a smelting process, enough aluminum blocks for deoxidizing are added at one step in a tapping process, and no aluminum is replenished in the subsequent process, so that a deoxidized product is prevented from being floated; the content of Al in the refining slag is controlled at about 0.010%, so that secondary oxidation caused in a pouring process is reduced. On the other hand, the value of CaO / Al2O3 in the refining slag is controlled at about 1.7, so that the melting point of slag is relatively low, the flowability of the slag is relatively good, the steel slag is easy to separate, and the slag rolling and reduction reaction of molten steel in a vacuumizing process are reduced. Therefore, D-type inclusions in the bearing steel are effectively prevented from being increased, and the rating standards of inclusions in the bearing steel are reached.

Description

technical field [0001] The invention belongs to the field of metallurgy and relates to a smelting process, in particular to a smelting process of high-carbon bearing steel. Background technique [0002] The non-metallic inclusions in bearing steel are the key factors affecting its service life, and a considerable part of the non-metallic inclusions in steel is caused by oxygen, so the rating of inclusions in steel and the oxygen content in steel are often used as a measure of bearing steel important indicator of quality. [0003] In order to effectively deoxidize and remove the inclusions in the steel to the greatest extent, so that the bearing steel can obtain higher cleanliness and quality, after determining the deoxidizer, select the appropriate slag material component to determine the physical and chemical properties of the refining slag. extremely important. For high-quality, high-cleanness bearing steel, the principles for determining the chemical composition of the ...

AI Technical Summary

Problems solved by technology

In order to reduce the oxygen content of bearing steel to a lower level, the refining slag generally requires a higher dissolved [Al] content in the steel during the production process, and even additional aluminum wires are added during the refining process, resulting in deoxidized products in the molten steel It is difficult to completely form clustered inclusions that are conducive to floating; in addition, because the Al in the slag 2 o 3 The content is low, the melting point of refining slag is relatively high, and the ability of refining slag to absorb spherical inclusions is limited

[0005] Although high-alkalinity refining slag is beneficial to the desulfurization and deoxidation of bearing steel, it is easy to form brittle inclusions in molten steel during the smelting process of bearing steel, which will greatly endanger the life of bearing steel. CaO or MgO in the furnace lining is reduced by [Al] or [C] in the steel and enters the molten steel, and combines with Al deoxidized products to form Ca, Mg, Al, O composite products, due to insufficient flotation, it stays in the molten steel, forming large-grained brittle inclusions

[0006] The patent with the publication number CN1621538 discloses a method for reducing and refining high-carbon bearing steel D-type inclusions, which uses high-basicity slag desulfurization at the LF station, low-basicity slag at the VD station, and VD Feed the aluminum wire 0.2~0.5kg / t after sampling. The advantage is that it can reduce the CaO activity in the slag during the vacuum process, thereby achieving the purpose of reducing the D-type inclusions. The disadvantage is that the inclusions formed by feeding the aluminum wire during the VD process are in the process. It is difficult to float in the middle, which increases the content of inclusions in the steel. In addition, the slag is made twice in the refining and vacuum process, and the cost is greatly increased.