Ladle furnace low alkalinity slag refining process

Abstract

The invention provides ladle furnace low alkalinity slag refining process. According to the process, bottom blowing of argon to ladles is carried out in the whole course of steel making and tapping, and ferrosilicon, silicon-calcium-barium and high carbon ferromanganese are sequentially added into the ladles for deoxidation and alloying; under the condition that argon flow is 30 to 50 NL / min, argon is blown to the liquid steel for two to three minutes, electrodes are inserted to melt slag, and the slag is modified; the liquid steel is heated to a temperature of 1580 to 1600 DEG C, and alkalinity of the slag is controlled to be 0.8 to 1.3; under the condition that argon flow is 20 to 30 NL / min, argon is blown to the liquid steel for 25 to 30 minutes, and components of the slag are controlled. Therefore, compound inclusion particles with a low melting point and good plastic deformation are formed in the liquid steel and float upward rapidly, which is beneficial for effective removal of inclusions in the liquid steel, thereby substantially improving cleanliness of the liquid steel, obviously enhancing quality of billets, enabling defects of billets like looseness, cracks, segregationand non-metallic inclusions to be greatly reduced, the content of micro inclusions, especially inclusions of B type oxides and D type oxides, in steel products to be substantially reduced and the steel products to meet subsequent processing requirements of 70 high carbon steel wires and 60 Si2Mn spring steel.

Description

[0001] technical field [0002] The invention relates to an LF furnace refining process, in particular to an LF furnace low-alkalinity slag refining process, which belongs to the technical field of steelmaking. Background technique [0003] With the increasing requirements of users for steel quality, ladle refining furnace (Ladle Furnace referred to as LF furnace) has developed rapidly as a means of improving the cleanliness of molten steel and improving steel quality, and has become an indispensable process in the short process of modern steel production. . In addition to adopting more mature secondary refining technologies such as submerged arc heating in reducing atmosphere, vacuum degassing, argon blowing and stirring with breathable bricks, LF refining furnace also introduces synthetic slag refining technology to achieve desulfurization and deoxidation through reasonable slagging process Even for the purpose of denitrification, so as to effectively absorb the inclusion...

AI Technical Summary

Problems solved by technology

However, the alkalinity of refining slag should not be too high. If the alkalinity is too high, such as greater than 5, the viscosity of refining slag will be too high, melting will be difficult, and fluidity will be poor, which will eventually affect the deoxidation and desulfurization effects of molten steel.

At present, in the production of domestic aluminum-killed steel and other varieties of steel, the basicity (CaO / SiO 2 ) are generally greater than 2, which belongs to the high-basicity slag refining process, which has good desulfurization and degassing effects, but this process is not conducive to the effective control of oxide inclusions such as B and D, and the oxides of B and D It is an inclusion with a high melting point and no deformation. The interface between it and the steel base will generate quality defects such as microcracks and voids, which will significantly reduce the fatigue and drawing properties of the steel during subsequent processing, which is not conducive to the improvement of steel properties.

Since the high-alkalinity slag refining process of the LF furnace is difficult to effectively control the amount of non-deformable spherical oxides in the steel, the quality control is unstable and difficult in the production of high-carbon hard wire steel, spring steel and other steels that have strict requirements on inclusions. Meet the requirements of subsequent processing

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