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Production method for increasing continuous pouring times for calcium-free treatment of cold heading steel in furnace

A production method and calcium treatment technology, applied in the field of metallurgy, can solve problems such as production interruption, and achieve the effect of reducing the risk of large-particle inclusions exceeding the standard and avoiding nozzle nodules

Inactive Publication Date: 2020-12-15
XINGTAI IRON & STEEL
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Problems solved by technology

Large DS inclusions in cold heading steel are mainly liquid CaO-Al after calcium treatment 2 o 3 Composite inclusions enter the molten steel and cannot be removed through the steel slag reaction, while the inclusions in molten steel produced by the calcium-free treatment process mainly exist in the form of high melting points, which are easy to accumulate and form nodules inside the nozzle during the pouring process of the continuous casting machine. Severe formation of nodules at the nozzle after 5-6 furnaces of continuous pouring by the machine led to production interruption

Method used

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  • Production method for increasing continuous pouring times for calcium-free treatment of cold heading steel in furnace

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Effect test

Embodiment 1

[0023] In the converter smelting process, the dissolved oxygen content in the molten steel at the end of the smelting process is 385ppm. In the converter tapping process, deoxidation and alloying are carried out during the tapping process, so that the Al content in the incoming molten steel composition of the LF furnace is 0.025%, and high alkali is added when tapping 2 / 3 of the converter Pre-melted slag and lime, the amount of pre-melted slag and lime added is 3.5kg / ton of steel, and the binary alkalinity of ladle slag is controlled at 10.0. LF process, add lime 2.5kg / ton of steel when the LF furnace starts heating for 0.5 minutes, control the binary alkalinity of the refining slag to be 13.0 when the LF furnace starts heating; feed aluminum wires to control the aluminum content of molten steel at 0.052 when the LF furnace is treated for 12 minutes %, the aluminum content of the finished molten steel is controlled to be 0.015%, and the feeding time of the aluminum wire ensures...

Embodiment 2

[0025] In the converter smelting process, the dissolved oxygen content in the molten steel at the end of the smelting process is 413ppm. In the converter tapping process, deoxidation and alloying are carried out during the tapping process, so that the Al content in the incoming molten steel composition of the LF furnace is 0.029%, and high alkalinity is added when the converter tapping reaches 70%. Pre-melted slag and lime, the amount of pre-melted slag and lime added is 3.75kg / ton of steel, and the binary basicity of ladle slag is controlled at 9.2. In the LF process, add lime 2.6kg / ton of steel when the LF furnace starts heating for 0.7 minutes, and control the binary alkalinity of the refining slag to be 12.0 when the LF furnace starts heating; feed aluminum wire to control the aluminum content of molten steel at 0.051 when the LF furnace is treated for 5 minutes %, the aluminum content of the finished molten steel is controlled to be 0.024%, and the aluminum wire feeding ti...

Embodiment 3

[0027] In the converter smelting process, the dissolved oxygen content in the molten steel at the end of the smelting process is 345ppm. In the converter tapping process, deoxidation and alloying are carried out during the tapping process, so that the Al content in the incoming molten steel composition of the LF furnace is 0.035%, and high alkalinity is added when the converter tapping is 65%. Pre-melted slag and lime, the amount of pre-melted slag and lime added is 3.65kg / ton of steel respectively, and the binary basicity of ladle slag is controlled at 9.4. In the LF process, add lime 2.7kg / ton of steel when the LF furnace starts heating for 0.9 minutes, and control the binary alkalinity of the refining slag to be 11.0 when the LF furnace starts heating; feed aluminum wires to control the aluminum content of molten steel at 0.053 when the LF furnace starts heating for 11 minutes %, the aluminum content of the finished molten steel is controlled to be 0.023%, and the aluminum w...

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Abstract

The invention relates to a production method for increasing the continuous pouring times for calcium-free treatment of cold heading steel in a furnace. The production method comprises the following steps of: controlling the binary alkalinity of refining slag to be 9.0-13.0 when an LF furnace starts to heat; evenly scattering ferrosilicon powder is to the surface of the refining slag for slagging after 10-15 min of treatment of an LF furnace, where the added amount of the ferrosilicon powder is 0.8-1.4 kg per ton of steel, and the binary alkalinity of the refining slag is controlled to be 2.8-4.5; and after 5-15 min of treatment of the LF furnace, feeding an aluminum wire to control the aluminum content of molten steel to be 0.050% to 0.060%, controlling the aluminum content of a finished molten steel product to be 0.015% to 0.030%, and ensuring that the aluminum wire is fed before ferrosilicon powder is added; wherein final slag of the LF furnace comprises the following components in percentage: 48% to 58% of CaO, 13% to 17% of SiO2, 20% to 30% of Al2O3 and 4% to 8% of MgO. The production method provided by the invention prevents nodulation of a sprue in a pouring process of a steel billet and realizes 15-20 times of continuous pouring for calcium-free treatment of the molten steel in the furnace.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a production method for increasing the number of continuous casting furnaces for calcium-free treated cold heading steel. Background technique [0002] Cold heading steel is widely used in the production of standard parts such as screws and nuts. Among them, SCM435 series cold heading steel belongs to high-grade cold heading steel with special requirements, which is applied to high-strength bolts of grade 10.9 and above. The fatigue life of steel is significantly affected, so the requirements for inclusions in steel are very strict when used in passenger car parts such as engine bolts. Large DS inclusions in cold heading steel are mainly liquid CaO-Al after calcium treatment 2 o 3 Composite inclusions enter the molten steel and cannot be removed through the steel slag reaction, while the inclusions in molten steel produced by the calcium-free treatment process ma...

Claims

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Application Information

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IPC IPC(8): C21C7/00C21C7/10C21C7/072C21C7/076C21C5/28
CPCC21C5/28C21C7/0037C21C7/0056C21C7/072C21C7/076C21C7/10Y02P10/20
Inventor 李刚郭键叶凡新赵彦岭李富伟李智刚阎丽珍修建军李永超李敏锐和红杰刘学强
Owner XINGTAI IRON & STEEL
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