Semi-molten steel smelting control method for eliminating white spots of rolling oil scraping cylinder

Abstract

The invention provides a semi-molten steel smelting control method for eliminating white spots of a rolling oil scraping cylinder, which comprises the following steps: (1) smelting and desulfurizing semi-molten steel: sequentially carrying out vanadium extraction blowing and KR deep desulfurization on the semi-molten steel, and controlling the S content in the semi-molten steel subjected to KR deep desulfurization to be less than or equal to 0.02 wt%; (2) converter smelting, wherein refining top slag is pre-manufactured in the tapping process; (3) refining treatment: according to different steel types, the refining treatment comprises a refining desulfurization process and a refining non-desulfurization process; and (4) continuous casting protective pouring. According to the method, effective desulfurization is achieved before refining treatment, stable maintenance of a refining slag system is achieved by reasonably regulating and controlling the slag proportion in the refining treatment, inclusions are fully promoted to float upwards and be adsorbed, finally, the core quality of a casting blank is further stably controlled through continuous casting, the inclusions are prevented from being gathered at the core position, and the quality of the casting blank is improved. And the white spot defect of the steel for the rolling oil scraping cylinder can be thoroughly eliminated.

Description

Technical Field

[0001] The invention belongs to the field of steel smelting, and relates to a white spot control method, in particular to a semi-molten steel smelting control method for eliminating white spots on a rolling and scraping cylinder. Background Art

[0002] In recent years, with the need for high-quality development and transformation of the national economy, high-end customers have strict quality requirements. Among them, the inner wall of the rolling scraper cylinder tube has very high quality requirements to meet the high-strength and harsh working environment conditions that the inner wall faces for a long time. However, for a long time, due to the influence of process technology and equipment level, deep desulfurization will affect vanadium indicators, steelmaking inclusions and large particle inclusion control, etc., which has been plaguing the stable control of the inner wall quality of the rolling scraper cylinder tube, seriously restricting the expansion of high-end varieties and high-end customers.

[0003] At present, there are process technologies for reducing inclusions in steel grades. For example, CN 111378810A discloses a refining process for reducing the size and number of non-metallic inclusions in steel. The refining process specifically includes the following steps: (i) adding aluminum blocks for deoxidation during the converter steel-tapping process to control the oxygen content within 100 ppm, the converter steel-tapping time is ≥5 min, and slag is strictly prohibited during the steel-tapping process; (ii) in the early stage of LF refining, argon is blown from the bottom at a flow rate of 0.5 to 1 Nm / h, and aluminum wire is added at the same time to control the oxygen content within the range of 30 to 60 ppm; (iii) in the late stage of LF refining, quartz sand is added, and then pure calcium wire is fed, and the argon flow rate is increased to 4 to 5 Nm 3 / h bottom blowing for 1 to 2 minutes, then reduce the argon flow rate to 0.5 to 1 Nm 3 / h bottom blowing for 3-5min, and controlling the CaO / SiO ratio at 4.0-6.0; (iv) after RH refining vacuum breaking, feed pure calcium wire, and then static stirring for a total time of ≥25 minutes. CN 111964950A discloses a method for controlling titanium nitride inclusions in 35MnB series engineering machinery steel bars, comprising the following steps: during converter smelting of molten iron, controlling the C mass percentage at the converter end point to be 0.09-0.14% or the steel tapping TSO oxygen level ≤400ppm, and the steel tapping temperature ≥1560℃; adding graphite carbon powder and deoxidizer for pre-deoxidation in the early stage of steel tapping, and then adding alloy for deoxidation alloying, and maintaining argon blowing throughout the deoxidation alloying process.

[0004] Although the process provided by the above patent reduces the inclusions in the steel, it does not completely eliminate the white spots.

[0005] In summary, it is necessary to provide a steelmaking process method to completely eliminate white spot defects. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a semi-molten steel smelting control method for eliminating white spots on rolling and scraping cylinders. The method provided by the present invention realizes effective desulfurization before refining treatment, and through the reasonable regulation of the slag ratio during the refining treatment, the stable maintenance of the refined slag system is achieved, which fully enables inclusions to float and be adsorbed, and finally, through continuous casting, the stable control of the core quality of the ingot is further achieved, avoiding the accumulation of inclusions at the core position, thereby completely eliminating the white spot defects of steel for rolling and scraping cylinders.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder, the semi-molten steel smelting control method comprising the following steps:

[0009] (1) Semi-molten steel smelting desulfurization:

[0010] The semi-steel is subjected to vanadium extraction blowing and KR deep desulfurization in sequence, the C content in the semi-steel obtained by the vanadium extraction blowing is controlled to be 3.0-3.3wt%, and the S content in the semi-steel after the KR deep desulfurization is controlled to be ≤0.02wt%;

[0011] (2) Converter smelting:

[0012] The end point C content of the converter smelting is controlled to be ≥0.08wt% and the S content is ≤0.025wt%; the top slag is pre-made and refined during the steel tapping process;

[0013] (3) Refining treatment:

[0014] According to different steel types, the refining treatment includes a refining and desulfurization process and a refining and non-desulfurization process;

[0015] The refining process includes the following steps: molten steel arrival, temperature adjustment, sampling and temperature measurement, composition adjustment and post-processing;

[0016] (4) Continuous casting protection pouring.

[0017] In the present invention, based on the fact that the formation of inclusions in the steel for rolling and scraping cylinders is closely related to the sulfur content, the KR deep desulfurization process can effectively remove the sulfur element and control the S content in the semi-molten steel to be ≤0.02wt%, which can greatly reduce the subsequent desulfurization and deoxidation pressure and ensure that the S content at the refining process is ≤0.025wt%; at the same time, through the reasonable regulation of the slag ratio in the refining process, the stable maintenance of the refining slag system is achieved, which fully promotes the floating and adsorption of inclusions, and finally, through continuous casting, the stable control of the core quality of the casting is further achieved, avoiding the accumulation of inclusions at the core position, and thus the white spot defects of the steel for rolling and scraping cylinders can be completely eliminated.

[0018] The inclusion control level of the steel ingot obtained by adopting the semi-molten steel smelting control method provided by the present invention reaches Class A≤0.5 level, and Class B and Class D≤1.0 level.

[0019] Exemplarily, the C content in the semi-steel water obtained by the vanadium extraction blowing in step (1) is 3.0-3.3wt%, for example, it can be 3.0wt%, 3.05wt%, 3.1wt%, 3.15wt%, 3.2wt%, 3.25wt% or 3.3wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] The S content in the semi-molten steel after the KR deep desulfurization in step (1) is ≤0.02wt%, for example, it can be 0.02wt%, 0.018wt%, 0.016wt%, 0.014wt%, 0.012wt% or 0.01wt%, etc., but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable;

[0021] The endpoint C content of the converter smelting in step (2) is ≥0.08wt%, for example, it can be 0.08wt%, 0.085wt%, 0.09wt%, 0.095wt% or 0.1wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable; the S content is ≤0.025wt%, for example, it can be 0.025wt%, 0.023wt%, 0.021wt%, 0.019wt%, 0.017wt% or 0.015wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0022] As a preferred technical solution of the present invention, the temperature of the semi-steel water in the KR deep desulfurization in step (1) is 1350-1415°C, for example, it can be 1350°C, 1360°C, 1370°C, 1380°C, 1390°C, 1400°C, 1410°C or 1415°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, lime powder is stirred and mixed in the KR deep desulfurization in step (1).

[0024] Preferably, the addition amount of the lime powder is 17-21 kg / t molten steel, for example, it can be 17 kg / t molten steel, 18 kg / t molten steel, 19 kg / t molten steel, 20 kg / t molten steel or 21 kg / t molten steel, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, the stirring and mixing time is 16 to 18 minutes, for example, 16 minutes, 16.5 minutes, 17 minutes, 17.5 minutes or 18 minutes, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] In the present invention, by limiting the temperature, C content and stirring and mixing time of semi-molten steel in KR deep desulfurization, the desulfurization effect is improved, so that the S content in the semi-molten steel after KR deep desulfurization is ≤0.02wt%.

[0027] As a preferred technical solution of the present invention, the double sliding slag blocking technology is adopted in the converter smelting in step (2) to achieve the purpose of not increasing sulfur in the converter smelting process.

[0028] As a preferred technical solution of the present invention, lime and refining slag are mixed in the prefabricated refining top slag in step (2).

[0029] Preferably, the amount of lime added is 450-550 kg, for example, 450 kg, 470 kg, 490 kg, 510 kg, 530 kg or 550 kg, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, the amount of refined slag added is 250-350 kg, for example, 250 kg, 270 kg, 290 kg, 310 kg, 330 kg or 350 kg, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] Preferably, the timing of pre-making the refined top slag in step (2) is the converter steel-tapping process.

[0032] In the present invention, the purpose of the pre-made refining top slag is to pre-deoxidize, create preliminary conditions for refining and desulfurization, and stabilize the formation of the final refining slag system.

[0033] It is worth noting that during the refining process described in step (3) of the present invention, the sampling and temperature measurement process is carried out during the temperature adjustment process, the purpose of which is to adjust the composition of the molten steel to meet the requirements, adjust the temperature fluctuation in a narrow range, control the overheat of continuous casting, and better control the dense solidification of the core of the ingot.

[0034] In addition, during the refining process of step (3), the post-treatment is specifically to adjust the composition of the molten steel and adjust the argon gas to enable the inclusions to fully float and be adsorbed by the refining slag.

[0035] As a preferred technical solution of the present invention, the temperature adjustment treatment in step (3) includes: in the process of mixing silicon carbide powder and aluminum particles, performing primary electrode refining and secondary electrode refining in sequence.

[0036] The specific process of the primary electrode refining and the secondary electrode refining of the present invention is: mixing lime powder for refining when the electrode is lowered.

[0037] Preferably, the amount of silicon carbide powder added in the temperature adjustment treatment in step (3) is 80 to 100 kg, for example, 80 kg, 85 kg, 90 kg, 95 kg or 100 kg, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] Preferably, the amount of aluminum particles added in the temperature adjustment treatment in step (3) is 20 to 40 kg, for example, 20 kg, 25 kg, 30 kg, 35 kg or 40 kg, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] Preferably, the amount of lime powder added in the primary electrode refining is 200-300 kg, for example, 200 kg, 220 kg, 240 kg, 260 kg, 280 kg or 300 kg, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] Preferably, the time for the primary electrode refining is ≥15 min, for example, it can be 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] Preferably, the aluminum content is adjusted to 0.055-0.070% after the primary electrode refining, for example, it can be 0.055%, 0.06%, 0.065% or 0.070%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0042] Preferably, the amount of lime powder added in the secondary electrode refining is 80-120 kg, for example, 80 kg, 90 kg, 100 kg, 110 kg or 120 kg, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0043] Preferably, the secondary electrode refining time is ≥10 min, for example, it can be 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] As a preferred technical solution of the present invention, the mass percentage components of the refined slag system after the temperature adjustment treatment include: CaO content of 56.65-57.53wt%, SiO2 content of 11.42-13.00wt%, Al2O3 content of 21.94-22.16wt%, and FeO content of 0.5-0.94wt%.

[0045] Exemplarily, the CaO content in the refined slag system is 56.65-57.53wt%, for example, it can be 56.65wt%, 56.85wt%, 57.05wt%, 57.25wt%, 57.45wt% or 57.53wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0046] The SiO2 content in the refined slag system is 11.42-13.00wt%, for example, it can be 11.42wt%, 11.7wt%, 12.0wt%, 12.3wt%, 12.6wt%, 12.9wt% or 13.00wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0047] The Al2O3 content in the refined slag system is 21.94-22.16wt%, for example, it can be 21.94wt%, 21.98wt%, 22.03wt%, 22.08wt%, 22.12wt% or 22.16wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0048] The FeO content in the refined slag system is 0.5-0.94wt%, for example, it can be 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 0.94wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0049] In the present invention, by respectively limiting the slag materials in the prefabricated top slag, primary electrode refining and secondary electrode refining processes, the refining slag system is stably maintained after the temperature adjustment treatment is completed, so that a low melting point and high basicity refining slag system is formed. The slag system has significant advantages such as high sulfur capacity, low melting temperature, fast slagging, good fluidity, and strong deoxidation and adsorption capacity of inclusions. Its reasonable slag system ratio, combined with aluminum and silicon slag surface diffusion deoxidation, can keep the oxides w(MnO)+w(FeO) in the slag below 1%, thereby ensuring that the slag always has a strong deoxidation and adsorption capacity of non-metallic inclusions in steel.

[0050] As a preferred technical solution of the present invention, the composition adjustment treatment in step (3) includes feeding metal wire, or a combination of a mixed carburizer, an alloy block and a feeding metal wire.

[0051] In the present invention, whether to add a carburizer and an alloy block is determined according to the composition adjustment result.

[0052] Preferably, the metal wire includes an alloy wire and an aluminum wire.

[0053] Preferably, the feeding rate of the metal wire is 3.5-4.0 m / s, for example, 3.5 m / s, 3.6 m / s, 3.7 m / s, 3.8 m / s, 3.9 m / s or 4.0 m / s, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0054] Preferably, the alloy wire comprises calcium silicon wire.

[0055] Preferably, the first furnace addition amount of the silicon-calcium wire is 0.8-1.2 m / t steel, for example, it can be 0.8 m / t steel, 0.9 m / t steel, 1.0 m / t steel, 1.1 m / t steel or 1.2 m / t steel, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0056] Preferably, the amount of aluminum wire added is 20 to 60 m / furnace, for example, 20 m / furnace, 30 m / furnace, 40 m / furnace, 50 m / furnace or 60 m / furnace, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0057] According to different types of steel, the present invention divides the refining process into a refining and desulfurization process and a refining and non-desulfurization process; the present invention can fully float and adsorb inclusions by regulating the flow rate and pressure of the inert gas at each stage of the refining process, thereby further improving the removal of inclusions;

[0058] Furthermore, in the refining treatment, it is appropriate that the liquid surface of the molten steel is exposed by 200 to 300 mm. By controlling the flow rate and pressure of the inert gas, it is possible to ensure that the molten steel does not roll up slag, effectively remove inclusions in the steel, and fully contact the slag for desulfurization. The temperature control treatment can ensure that the composition and temperature of the molten steel are uniform, and the exposed area of ​​the molten steel surface is small, thereby avoiding secondary oxidation of the molten steel.

[0059] As a preferred technical solution of the present invention, in the refining and desulfurization process, the flow rate of inert gas during the arrival of molten steel at the station is 600-800 L / min, for example, it can be 600 L / min, 640 L / min, 680 L / min, 720 L / min, 760 L / min or 800 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0060] Preferably, in the refining and desulfurization process, the pressure of the inert gas during the arrival of the molten steel at the station is ≥0.6MPa, for example, it can be 0.6MPa, 0.62MPa, 0.64MPa, 0.66Mpa, 0.68MPa or 0.7MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0061] Preferably, in the refining and desulfurization process, the flow rate of the inert gas after the shell is broken when the molten steel arrives at the station is 20 to 180 L / min, for example, it can be 20 L / min, 60 L / min, 100 L / min, 140 L / min or 180 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0062] Preferably, in the refining and desulfurization process, the pressure of the inert gas after the shell is broken when the molten steel arrives at the station is 0.2-0.25 MPa, for example, it can be 0.2 MPa, 0.21 MPa, 0.22 MPa, 0.23 MPa, 0.24 MPa or 0.25 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0063] Preferably, in the refining and desulfurization process, the flow rate of the inert gas during the temperature adjustment treatment is 80 to 400 L / min, for example, it can be 80 L / min, 120 L / min, 160 L / min, 200 L / min, 240 L / min, 280 L / min, 320 L / min, 360 L / min or 400 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0064] Preferably, in the refining and desulfurization process, the pressure of the inert gas during the temperature adjustment treatment is 0.23-0.45 MPa, for example, it can be 0.23 MPa, 0.29 MPa, 0.33 MPa, 0.37 MPa, 0.41 MPa or 0.45 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0065] Preferably, in the refining desulfurization process, the flow rate of the inert gas during the sampling and temperature measurement process is 150-250 L / min, for example, it can be 150 L / min, 170 L / min, 190 L / min, 210 L / min, 230 L / min or 250 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0066] Preferably, in the refining desulfurization process, the pressure of the inert gas during the sampling and temperature measurement process is 0.25-0.35 MPa, for example, it can be 0.25 MPa, 0.27 MPa, 0.29 MPa, 0.31 MPa, 0.33 MPa or 0.35 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0067] Preferably, in the refining desulfurization process, the flow rate of the inert gas when mixing the carburizer in the composition adjustment treatment is 600-800 L / min, for example, it can be 600 L / min, 640 L / min, 680 L / min, 720 L / min, 760 L / min or 800 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0068] Preferably, in the refining desulfurization process, the pressure when mixing the carburizer during the composition adjustment treatment is 0.55-0.65 MPa, for example, it can be 0.55 MPa, 0.57 MPa, 0.59 MPa, 0.61 MPa, 0.63 MPa or 0.65 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0069] Preferably, in the refining desulfurization process, the recarburizer is mixed during the composition adjustment process and stirred for 2 to 3 minutes, for example, 2 minutes, 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes or 3 minutes, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0070] Preferably, in the refining and desulfurization process, the flow rate of the inert gas when feeding the alloy wire and the aluminum wire in the composition adjustment treatment is 200-400 L / min, for example, it can be 200 L / min, 240 L / min, 280 L / min, 320 L / min, 360 L / min or 400 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0071] Preferably, in the refining and desulfurization process, the pressure when feeding the alloy wire and the aluminum wire in the composition adjustment treatment is 0.4-0.5 MPa, for example, it can be 0.4 MPa, 0.42 MPa, 0.44 MPa, 0.46 MPa, 0.48 MPa or 0.5 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0072] Preferably, in the refining desulfurization process, the flow rate of the inert gas in the post-treatment is 100-200 L / min, for example, it can be 100 L / min, 120 L / min, 140 L / min, 160 L / min, 180 L / min or 200 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0073] Preferably, in the refining desulfurization process, the pressure of the inert gas in the post-treatment is 0.23-0.33 MPa, for example, it can be 0.23 MPa, 0.25 MPa, 0.27 MPa, 0.29 MPa, 0.31 MPa or 0.33 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0074] As a preferred technical solution of the present invention, in the refining without desulfurization process, the flow rate of inert gas during the arrival of molten steel at the station is 250-350 L / min, for example, it can be 250 L / min, 270 L / min, 290 L / min, 310 L / min, 330 L / min or 350 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0075] Preferably, in the refining without desulfurization process, the pressure of the inert gas during the arrival of the molten steel at the station is ≥0.4MPa, for example, it can be 0.4MPa, 0.42MPa, 0.46MPa, 0.48MPa or 0.5MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0076] Preferably, in the refining without desulfurization process, the flow rate of the inert gas after the shell is broken during the arrival of the molten steel at the station is 20 to 100 L / min, for example, it can be 20 L / min, 40 L / min, 60 L / min, 80 L / min or 100 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0077] Preferably, in the refining without desulfurization process, the pressure of the inert gas after the shell is broken during the arrival of the molten steel at the station is 0.2-0.25 MPa, for example, it can be 0.2 MPa, 0.21 MPa, 0.22 MPa, 0.23 MPa, 0.24 MPa or 0.25 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0078] Preferably, in the refining without desulfurization process, the flow rate of the inert gas during the temperature adjustment treatment is 150-250 L / min, for example, it can be 150 L / min, 170 L / min, 190 L / min, 210 L / min, 230 L / min or 250 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0079] Preferably, in the refining without desulfurization process, the pressure of the inert gas during the temperature adjustment treatment is 0.25-0.40 MPa, for example, it can be 0.25 MPa, 0.28 MPa, 0.31 MPa, 0.34 MPa, 0.37 MPa or 0.40 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0080] Preferably, in the refining without desulfurization process, the flow rate of the inert gas during the sampling and temperature measurement process is 100-200 L / min, for example, it can be 100 L / min, 120 L / min, 140 L / min, 160 L / min, 180 L / min or 200 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0081] Preferably, in the refining without desulfurization process, the pressure of the inert gas during sampling and temperature measurement is 0.23-0.35 MPa, for example, it can be 0.23 MPa, 0.25 MPa, 0.27 MPa, 0.29 MPa, 0.31 MPa, 0.33 MPa or 0.35 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0082] Preferably, in the refining without desulfurization process, the flow rate of the inert gas when mixing the carburizer in the composition adjustment treatment is 600-700 L / min, for example, it can be 600 L / min, 620 L / min, 640 L / min, 660 L / min, 680 L / min or 700 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0083] Preferably, in the refining without desulfurization process, the pressure when mixing the carburizer in the composition adjustment process is 0.55-0.65 MPa, for example, it can be 0.55 MPa, 0.57 MPa, 0.59 MPa, 0.61 MPa, 0.63 MPa or 0.65 MPa, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. ;

[0084] Preferably, in the refining without desulfurization process, the recarburizer is mixed in the composition adjustment process and stirred for 2 to 3 minutes, for example, 2 minutes, 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes or 3 minutes, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0085] Preferably, in the refining without desulfurization process, the flow rate of the inert gas when feeding the alloy wire and the aluminum wire in the composition adjustment treatment is 200-300 L / min, for example, it can be 200 L / min, 220 L / min, 240 L / min, 260 L / min, 280 L / min or 300 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0086] Preferably, in the refining without desulfurization process, the pressure when feeding the alloy wire and the aluminum wire in the composition adjustment treatment is 0.4-0.5 MPa, for example, it can be 0.4 MPa, 0.42 MPa, 0.44 MPa, 0.46 MPa, 0.48 MPa or 0.5 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0087] Preferably, in the refining without desulfurization process, the flow rate of the inert gas in the post-treatment is 100-200 L / min, for example, it can be 100 L / min, 120 L / min, 140 L / min, 160 L / min, 180 L / min or 200 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0088] Preferably, in the refining without desulfurization process, the pressure of the inert gas in the post-treatment is 0.23-0.33 MPa, for example, it can be 0.23 MPa, 0.25 MPa, 0.27 MPa, 0.29 MPa, 0.31 MPa or 0.33 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0089] As a preferred technical solution of the present invention, the inert gas includes any one of argon, nitrogen or helium, or a combination of at least two of them. Typical but non-limiting combinations include: a combination of argon and helium, a combination of argon and nitrogen, a combination of nitrogen and helium, or a combination of argon, nitrogen and helium.

[0090] Preferably, the endpoint of the refining desulfurization process is an S content ≤ 0.002wt%, for example, it can be 0.002wt%, 0.0018wt%, 0.0016wt%, 0.0014wt%, 0.0012wt% or 0.001wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0091] Preferably, the endpoint of the refining without desulfurization process is an S content ≤ 0.015wt%, for example, it can be 0.015wt%, 0.014wt%, 0.013wt%, 0.012wt% or 0.011wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0092] As a preferred technical solution of the present invention, the steel types using the refining and desulfurization process include 25Mn or Q235B-1 / 21 / 13.

[0093] Preferably, the steel type using the refining without desulfurization process includes any one of H345B, 40Mn2 or 27SiMn.

[0094] As a preferred technical solution of the present invention, the continuous casting protective pouring in step (4) of the present invention adopts a continuous casting low-speed strong stirring mode to control the quality of the core of the ingot and avoid the accumulation of large particles in the core.

[0095] Preferably, the continuous casting protection pouring in step (4) adopts a large ladle steel retention operation and is controlled at 2.3-5.4 t / furnace, for example, it can be 2.3 t / furnace, 2.9 t / furnace, 3.5 t / furnace, 4.1 t / furnace, 4.7 t / furnace or 5.4 t / furnace, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0096] Preferably, in step (4) of continuous casting protection pouring, the automatic liquid level control fluctuation of the entire pouring is ≤±2mm, for example, it can be -2mm, -1mm, 1mm or 2mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0097] Preferably, the pulling speed in the continuous casting protective pouring in step (4) is 0.75-1.30 m / min, for example, it can be 0.75 m / min, 0.80 m / min, 0.90 m / min, 1.0 m / min, 1.1 m / min, 1.2 m / min or 1.3 m / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0098] Preferably, the stirring intensity in the continuous casting protective pouring in step (4) is 130-150A, for example, it can be 130A, 135A, 140A, 145A or 150A, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0099] It is worth mentioning that based on the automatic control technology of the tundish liquid level, the continuous casting control process of "constant temperature, constant speed, constant crystallizer liquid level, constant tundish liquid level + low speed + low superheat" has been optimized. Combined with the "crystallizer + end strong electromagnetic stirring" technology, the quality of the core of the ingot is stably controlled to avoid the accumulation of inclusions in the core position.

[0100] As a preferred technical solution of the present invention, the semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder provided by the present invention comprises the following steps:

[0101] (1) Semi-molten steel smelting and desulfurization;

[0102] The semi-steel is subjected to vanadium extraction blowing and KR deep desulfurization in sequence, the C content in the semi-steel obtained by the vanadium extraction blowing is controlled to be 3.0-3.3wt%, and the S content in the semi-steel after the KR deep desulfurization is controlled to be ≤0.02wt%;

[0103] (2) Converter smelting:

[0104] The end point C content of the converter smelting is controlled to be ≥0.08wt% and the S content is ≤0.025wt%; the top slag is pre-made and refined during the steel tapping process;

[0105] The prefabricated refining top slag is mixed with 450-550 kg of lime and 250-350 kg of refining slag;

[0106] (3) Refining treatment:

[0107] According to different steel types, the refining treatment includes a refining and desulfurization process and a refining and non-desulfurization process;

[0108] The refining process includes the following steps: molten steel arrival, temperature adjustment, sampling and temperature measurement, composition adjustment and post-processing;

[0109] The temperature adjustment treatment comprises: in the process of mixing silicon carbide powder and aluminum particles, performing primary electrode refining and secondary electrode refining in sequence; wherein the addition amount of the silicon carbide powder is 80-100kg, and the addition amount of the aluminum particles is 20-40kg; the addition amount of lime powder in the primary electrode refining is 200-300kg, the time is ≥15min, and the end point is that the aluminum content is 0.055-0.070%; the addition amount of lime powder in the secondary electrode refining is 80-120kg, and the time is ≥10min;

[0110] The mass percentage components of the refined slag system after the temperature adjustment treatment include: CaO content of 56.65-57.53wt%, SiO2 content of 11.42-13.00wt%, Al2O3 content of 21.94-22.16wt%, and FeO content of 0.5-0.94wt%;

[0111] The composition adjustment process includes feeding metal wire, or a combination of mixed carburizer, alloy block and feeding calcium silicon wire and aluminum wire; the mixed carburizer and alloy block are added according to the sampling results; the feeding rate of calcium silicon wire and aluminum wire is 3.5-4.0 m / s; the first furnace addition amount of calcium silicon wire is 0.8-1.2 m / t steel, and the addition amount of aluminum wire is 20-60 m / furnace;

[0112] When the steel type includes 25Mn or Q235B-1 / 21 / 13, a refining and desulfurization process is performed; in the refining and desulfurization process, the flow rate of the inert gas during the arrival of the molten steel is 600-800L / min, and the pressure is ≥0.6MPa; the flow rate of the inert gas after shell breaking is 20-180L / min, and the pressure is 0.2-0.25MPa; the flow rate of the inert gas during the temperature adjustment process is 80-400L / min, and the pressure is 0.23-0.45MPa; the flow rate of the inert gas during the sampling and temperature measurement process is 150~250L / min, pressure is 0.25~0.35MPa; the flow rate of inert gas when mixing carburizer in the composition adjustment treatment is 600~800L / min, pressure is 0.55~0.65MPa, stirring for 2~3min; the flow rate of inert gas when feeding alloy wire and aluminum wire in the composition adjustment treatment is 200~400L / min, pressure is 0.4~0.5MPa; the flow rate of inert gas in post-treatment is 100~200L / min, pressure is 0.23~0.33MPa;

[0113] When the steel grade includes any one of H345B, 40Mn2 or 27SiMn, a refining without desulfurization process is performed; the flow rate of the inert gas when the molten steel arrives at the station in the refining without desulfurization process is 250-350L / min, and the pressure is ≥0.4MPa; the flow rate of the inert gas after shell breaking is 20-100L / min, and the pressure is 0.2-0.25MPa; the flow rate of the inert gas during the temperature adjustment process is 150-250L / min, and the pressure is 0.25-0.40MPa; the flow rate of the inert gas during the sampling and temperature measurement is 150-250L / min, and the pressure is 0.25-0.40MPa; the flow rate of the inert gas during the sampling and temperature measurement is 150-250L / min, and the pressure is 0.25-0.40MPa. The flow rate of inert gas is 100-200L / min, and the pressure is 0.23-0.35MPa; the flow rate of inert gas when mixing carburizer in the composition adjustment treatment is 600-700L / min, the pressure is 0.55-0.65MPa, and stirring is 2-3min; the flow rate of inert gas when feeding alloy wire and aluminum wire in the composition adjustment treatment is 200-300L / min, and the pressure is 0.4-0.5MPa; the flow rate of inert gas in post-treatment is 100-200L / min, and the pressure is 0.23-0.33MPa;

[0114] (4) Continuous casting protection pouring:

[0115] The operation of retaining steel in a large ladle is adopted, and pouring is carried out in the continuous casting low casting speed strong stirring mode;

[0116] Among them, the automatic liquid level control fluctuation of the whole pouring is ≤±2mm, the pulling speed is 0.75~1.30m / min, and the stirring intensity is 130~150A.

[0117] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0118] Compared with the prior art, the present invention has the following beneficial effects:

[0119] (1) The inclusion control level of the steel ingot obtained by the semi-molten steel smelting control method for eliminating white spots on the rolling and scraping cylinder provided by the present invention reaches Class A ≤ Grade 0.5, Class B and Class D ≤ Grade 1.0, thereby completely eliminating the white spot defects of the rolling and scraping cylinder steel;

[0120] (2) The semi-molten steel smelting control method provided by the present invention can fully promote the floating and adsorption of inclusions by scientifically and reasonably allocating the inert gas flow rate and pressure at each stage of the refining process and regulating the composition and dosage of the refining slag during the refining process, and can further achieve stable control of the core quality of the ingot under the conditions of low-speed and strong stirring of continuous casting, thereby avoiding the accumulation of inclusions at the core position;

[0121] (3) The present invention can effectively remove sulfur elements through the KR deep desulfurization process and control the S content in the semi-molten steel to ≤ 0.02wt%, which can greatly reduce the subsequent desulfurization and deoxidation pressure. DETAILED DESCRIPTION

[0122] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0123] Example 1

[0124] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder, and the semi-molten steel smelting control method comprises the following steps:

[0125] (1) Semi-molten steel smelting and desulfurization;

[0126] The semi-steel water is subjected to vanadium extraction blowing and KR deep desulfurization in sequence, the C content in the semi-steel water obtained by the vanadium extraction blowing is controlled to be 3.15wt%, and the S content in the semi-steel water after the KR deep desulfurization is controlled to be 0.014wt%;

[0127] The temperature of the semi-molten steel in the KR deep desulfurization is 1380°C, and the lime powder is stirred and mixed for 17 minutes; the amount of lime powder added is 19kg / t molten steel;

[0128] (2) Converter smelting:

[0129] The end point C content of the converter smelting is controlled to be 0.09wt% and the S content is controlled to be 0.018wt%; the top slag is pre-made and refined during the steel tapping process;

[0130] 500 kg of lime and 300 kg of refined slag are mixed into the prefabricated refined top slag;

[0131] (3) Refining treatment:

[0132] According to different steel types, the refining treatment includes a refining and desulfurization process and a refining and non-desulfurization process;

[0133] The refining process includes the following steps: molten steel arrival, temperature adjustment, sampling and temperature measurement, composition adjustment and post-processing;

[0134] The temperature adjustment treatment includes: in the process of mixing silicon carbide powder and aluminum particles, performing primary electrode refining and secondary electrode refining in sequence; wherein the amount of silicon carbide powder added is 90 kg, and the amount of aluminum particles added is 30 kg; the amount of lime powder added in the primary electrode refining is 150 kg, the time is 16 minutes, and the end point is that the aluminum content is 0.062%; the amount of lime powder added in the secondary electrode refining is 100 kg, and the time is 10 minutes;

[0135] The mass percentage components of the refined slag system after the temperature adjustment treatment include: CaO content of 57.21wt%, SiO2 content of 12.57wt%, Al2O3 content of 22.08wt%, and FeO content of 0.78wt%;

[0136] The composition adjustment process includes: mixing a carburizer and feeding calcium silicon wire and aluminum wire; the feeding rate of calcium silicon wire and aluminum wire is 3.5-4.0 m / s; the first furnace addition amount of calcium silicon wire is 0.8-1.2 m / t steel, and the addition amount of aluminum wire is 20-60 m / furnace;

[0137] The steel grade of the rolling scraper cylinder described in this embodiment is 25Mn, and a refining and desulfurization process is performed; in the refining and desulfurization process, the flow rate of the inert gas during the arrival of the molten steel at the station is 700L / min, and the pressure is 0.8MPa; the flow rate of the inert gas after the shell is broken is 120L / min, and the pressure is 0.23MPa; the flow rate of the inert gas during the temperature adjustment process is 280L / min, and the pressure is 0.39MPa; the flow rate of the inert gas during the sampling and temperature measurement process is 200L / min, and the pressure is 0.3MPa; the flow rate of the inert gas when mixing the carburizer in the composition adjustment process is 700L / min, and the pressure is 0.6MPa, and the flow rate of the inert gas when feeding the alloy wire and the aluminum wire in the composition adjustment process for 2.5min is 300L / min, and the pressure is 0.45MPa; the flow rate of the inert gas in the post-treatment is 150L / min, and the pressure is 0.28MPa;

[0138] (4) Continuous casting protection pouring:

[0139] The operation of retaining steel in a large ladle is adopted, and pouring is carried out in the continuous casting low casting speed strong stirring mode;

[0140] Among them, the automatic liquid level control fluctuation of the whole pouring is ≤±1mm, the pulling speed is 1.10m / min, and the stirring intensity is 140A.

[0141] Example 2-3

[0142] Examples 2-3 respectively provide a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The differences between the semi-molten steel smelting control method and Example 1 are summarized in Table 1.

[0143] Table 1

[0144]

[0145]

[0146] Example 4

[0147] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from that of Embodiment 1 only in that:

[0148] In this embodiment, in the refining and desulfurization process of step (3), the flow rate of argon gas in the temperature adjustment treatment is adjusted to 50 L / min, and the pressure is adjusted to 0.2 MPa.

[0149] Example 5

[0150] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from that of Embodiment 1 only in that:

[0151] In this embodiment, in the refining and desulfurization process of step (3), the flow rate of argon gas in the temperature adjustment treatment is adjusted to 500 L / min, and the pressure is adjusted to 0.65 MPa.

[0152] Example 6

[0153] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from that of Embodiment 1 only in that:

[0154] In this embodiment, in the refining and desulfurization process of step (3), the flow rate of argon gas in the sampling and temperature measurement is adjusted to 100 L / min, and the pressure is adjusted to 0.2 MPa.

[0155] Example 7

[0156] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from that of Embodiment 1 only in that:

[0157] In this embodiment, in the refining and desulfurization process of step (3), the flow rate of argon gas in the sampling and temperature measurement is adjusted to 300 L / min, and the pressure is adjusted to 0.5 MPa.

[0158] Example 8

[0159] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from that of Embodiment 1 only in that:

[0160] In this embodiment, in the refining and desulfurization process described in step (3), the flow rate of argon gas in each stage is adjusted to 500 L / min, and the pressure is adjusted to 0.3 MPa.

[0161] Example 9

[0162] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from that of Embodiment 1 only in that:

[0163] In this embodiment, the steel grade to be processed is adjusted to H345B; the refining treatment in step (3) adopts a refining without desulfurization process; the flow rate of the inert gas when the molten steel arrives at the station in the refining without desulfurization process is 300L / min, and the pressure is 0.45MPa; the flow rate of the inert gas after shell breaking is 60L / min, and the pressure is 0.23MPa; the flow rate of the inert gas during the temperature adjustment process is 200L / min, and the pressure is 0.32MPa; the flow rate of the inert gas during the sampling and temperature measurement process is 150L / min, and the pressure is 0.3MPa; the flow rate of the inert gas when mixing the carburizer in the composition adjustment process is 650L / min, the pressure is 0.6MPa, and stirring is performed for 2.5min; the flow rate of the inert gas when feeding the alloy wire and the aluminum wire in the composition adjustment process is 250L / min, and the pressure is 0.45MPa; the flow rate of the inert gas in the post-treatment is 150L / min, and the pressure is 0.28MPa;

[0164] Example 10

[0165] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from that of Embodiment 9 only in that:

[0166] In this embodiment, in the refining without desulfurization process in step (3), the flow rate of argon gas in the temperature adjustment treatment is adjusted to 100 L / min, and the pressure is adjusted to 0.2 MPa.

[0167] Embodiment 11

[0168] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from that of Embodiment 9 only in that:

[0169] In this embodiment, in the refining without desulfurization process in step (3), the flow rate of argon gas in the temperature adjustment treatment is adjusted to 300 L / min, and the pressure is adjusted to 0.5 MPa.

[0170] Example 12

[0171] This embodiment provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from that of Embodiment 9 only in that:

[0172] In this embodiment, the flow rate of argon gas in each stage of the refining without desulfurization process in step (3) is adjusted to 300 L / min, and the pressure is adjusted to 0.3 MPa.

[0173] Comparative Example 1

[0174] This comparative example provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from Example 1 only in that:

[0175] In this embodiment, the C content in the semi-steel water obtained by the vanadium extraction blowing in step (1) is adjusted to 2.5wt%. At this time, the S content in the semi-steel water after the KR deep desulfurization is 0.045wt%.

[0176] Comparative Example 2

[0177] This comparative example provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from Example 1 only in that:

[0178] In this comparative example, the C content in the semi-steel water obtained by the vanadium extraction blowing in step (1) is adjusted to 3.8wt%. At this time, the S content in the semi-steel water after the KR deep desulfurization is 0.033wt%.

[0179] Comparative Example 3

[0180] This comparative example provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from Example 1 only in that:

[0181] In this comparative example, the temperature of the semi-molten steel in the KR deep desulfurization in step (1) is 1300°C, and the lime powder is stirred and mixed for 18 minutes; the amount of lime powder added is 20kg / t molten steel. At this time, the S content in the semi-molten steel after the KR deep desulfurization is 0.029wt%.

[0182] Comparative Example 4

[0183] This comparative example provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from Example 1 only in that:

[0184] In this comparative example, the temperature of the semi-molten steel in the KR deep desulfurization in step (1) is 1450°C, and the lime powder is stirred and mixed for 20 minutes; the amount of lime powder added is 20kg / t molten steel. At this time, the S content in the semi-molten steel after the KR deep desulfurization is 0.025wt%.

[0185] Comparative Example 5

[0186] This comparative example provides a semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder. The semi-molten steel smelting control method is different from Example 1 only in that:

[0187] In this comparative example, the process of pre-making the top slag of the refining process described in step (2) is omitted.

[0188] Performance testing:

[0189] (1) The inclusions of the steel ingots obtained by the semi-molten steel smelting control method provided by the above-mentioned embodiment and comparative example were characterized, and the results are shown in Table 2;

[0190] In the actual characterization process, 4 samples need to be inspected in each batch (the data in the table are the average values ​​of four data).

[0191] (2) The appearance of the scraping cylinder prepared by the steel ingot obtained by the semi-molten steel smelting control method provided in the above embodiment and comparative example was inspected to check whether there were white spots on its inner wall. The results are shown in Table 2.

[0192] Table 2

[0193]

[0194]

[0195] According to Table 2, we can know the following points:

[0196] (1) Comprehensive analysis of Examples 1-3 and Example 9 shows that for different steel grades, the method provided by the present invention can be used to reduce the inclusion content in the steel by adjusting the inert gas flow rate and pressure during the refining process, thereby achieving 100% elimination of white spots on the steel used for the rolling and scraping cylinder;

[0197] (2) Comprehensive analysis of Example 1 and Examples 4-12 shows that adjusting the flow rate and pressure of argon gas during the refining process will affect the removal of inclusions in steel;

[0198] Comprehensive analysis of Examples 1, 4-5, 9-11 shows that when the flow rate and pressure of the inert gas in the temperature adjustment process are low, large particle inclusions are not easy to float up and are captured and adsorbed by the refining slag system; on the contrary, when the flow rate and pressure of the inert gas in the temperature adjustment process are high, the molten steel will be rolled and the refining slag will be drawn into the molten steel, forming slag inclusions;

[0199] Comprehensive analysis of Example 1 and Examples 6-7 shows that when the flow rate and pressure of the inert gas in the sampling and temperature measurement process are too low or too high, foreign matter will not fully float up and Class D will exceed the standard;

[0200] Comprehensive analysis of Examples 1, 8-9 and Example 12 shows that, whether it is a refining desulfurization process or a refining non-desulfurization process, when the inert gas flow rate and pressure of the entire process are determined as fixed values ​​(i.e., the inert gas flow rate and pressure do not change with the change of the process flow), the overall desulfurization effect will be poor, and while changing the slag system affects the removal of inclusions, Class A inclusions will increase;

[0201] (3) Comprehensive analysis of Example 1 and Comparative Examples 1-4 shows that adjusting the semi-steel molten temperature, lime powder addition amount or stirring time during the KR deep desulfurization process will affect the desulfurization effect, so that the S content in the semi-steel molten after the KR deep desulfurization is greater than 0.02wt%, which leads to desulfurization and deoxidation during the refining process, large amounts of lime and aluminum particles are added, unbalanced refining slag system, and increased number of inclusions, especially increased number of Class B inclusions;

[0202] (4) Comprehensive analysis of Example 1 and Comparative Example 5 shows that when the pre-made top slag is omitted, the components of the refined slag will seriously deviate from the design value, fail to adsorb inclusions, and cause an overall increase in various types of inclusions in the molten steel.

[0203] In summary, the method provided by the present invention achieves effective desulfurization before refining treatment, and achieves stable maintenance of the refined slag system through reasonable regulation of the slag ratio during the refining treatment. Then, through scientific regulation of the refining process, the inclusions are fully promoted to float and be adsorbed, and the quality of the core of the ingot is further stably controlled during continuous casting to avoid the accumulation of inclusions in the core position, thereby completely eliminating the white spot defects of the steel used for the rolling and scraping cylinder.

[0204] The applicant declares that the specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A semi-molten steel smelting control method for eliminating white spots on a rolling and scraping oil cylinder, characterized in that: The semi-molten steel smelting control method comprises the following steps: (1) Semi-molten steel smelting desulfurization: The semi-steel is subjected to vanadium extraction blowing and KR deep desulfurization in sequence, the C content in the semi-steel obtained by the vanadium extraction blowing is controlled to be 3.0-3.3wt%, and the S content in the semi-steel after the KR deep desulfurization is controlled to be ≤0.02wt%; (2) Converter smelting: The end point C content of the converter smelting is controlled to be ≥0.08wt% and the S content is ≤0.025wt%; the top slag is pre-made and refined during the steel tapping process; (3) Refining treatment: According to different steel types, the refining treatment includes a refining and desulfurization process and a refining and non-desulfurization process; The refining process includes the following steps: molten steel arrival, temperature adjustment, sampling and temperature measurement, composition adjustment and post-processing; (4) Continuous casting protection pouring.

2. The semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder according to claim 1 is characterized in that: The temperature of the semi-molten steel in the KR deep desulfurization in step (1) is 1350-1415° C. Preferably, lime powder is stirred and mixed in the KR deep desulfurization in step (1); Preferably, the amount of lime powder added is 17-21 kg / t molten steel; Preferably, the stirring and mixing time is 16 to 18 minutes.

3. The semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder according to claim 1 or 2, characterized in that: Mixing lime and refined slag in the prefabricated refined top slag in step (2); Preferably, the amount of lime added is 450-550 kg; Preferably, the amount of refined slag added is 250-350 kg; Preferably, the timing of pre-making the refined top slag in step (2) is the converter steel-tapping process.

4. The semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder according to any one of claims 1 to 3, characterized in that: The temperature adjustment treatment in step (3) includes: performing primary electrode refining and secondary electrode refining in sequence during the process of mixing silicon carbide powder and aluminum particles; Preferably, the amount of silicon carbide powder added in the temperature adjustment treatment in step (3) is 80-100 kg; Preferably, the amount of aluminum particles added in the temperature adjustment treatment in step (3) is 20 to 40 kg; Preferably, the amount of lime powder added in the primary electrode refining is 200-300 kg; Preferably, the time of the primary electrode refining is ≥15min; Preferably, the aluminum content is adjusted to 0.055-0.070% after the primary electrode refining; Preferably, the amount of lime powder added in the secondary electrode refining is 80-120 kg; Preferably, the secondary electrode refining time is ≥10 min.

5. The semi-molten steel smelting control method for eliminating white spots on a rolling and scraping cylinder according to claim 4 is characterized in that: The weight percentage components of the refined slag after the temperature adjustment treatment include: CaO content of 56.65-57.53wt%, SiO2 content of 11.42-13.00wt%, Al2O3 content of 21.94-22.16wt%, and FeO content of 0.5-0.94wt%.

6. The semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder according to any one of claims 1 to 5, characterized in that: The composition adjustment treatment in step (3) includes feeding metal wire, or a combination of mixed carburizer, alloy block and feeding metal wire; Preferably, the metal wire comprises an alloy wire and an aluminum wire; Preferably, the alloy wire comprises calcium silicon wire; Preferably, the speed of feeding the metal wire is 3.5-4.0 m / s; Preferably, the addition amount of the calcium silicon wire is 0.8 to 1.2 m / t steel; Preferably, the amount of aluminum wire added is 20-60 m / furnace.

7. The semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder according to any one of claims 1 to 6, characterized in that: In the refining and desulfurization process, the flow rate of the inert gas during the arrival of molten steel at the station is 600-800 L / min; Preferably, in the refining and desulfurization process, the pressure of the inert gas during the arrival of molten steel at the station is ≥0.6MPa; Preferably, in the refining and desulfurization process, the flow rate of the inert gas after the shell is broken during the arrival of the molten steel at the station is 20 to 180 L / min; Preferably, in the refining and desulfurization process, the pressure of the inert gas after the molten steel is broken during arrival at the station is 0.2-0.25 MPa; Preferably, in the refining and desulfurization process, the flow rate of the inert gas during the temperature adjustment process is 80 to 400 L / min; Preferably, in the refining and desulfurization process, the pressure of the inert gas during the temperature adjustment process is 0.23-0.45 MPa; Preferably, in the refining and desulfurization process, the flow rate of the inert gas during the sampling and temperature measurement process is 150 to 250 L / min; Preferably, in the refining and desulfurization process, the pressure of the inert gas during sampling and temperature measurement is 0.25-0.35 MPa; Preferably, in the refining and desulfurization process, the flow rate of the inert gas when mixing the carburizer in the composition adjustment treatment is 600 to 800 L / min; Preferably, in the refining and desulfurization process, the pressure when the carburizer is mixed in the composition adjustment treatment is 0.55-0.65 MPa; Preferably, in the refining and desulfurization process, the recarburizer is mixed during the composition adjustment process and stirred for 2 to 3 minutes; Preferably, in the refining and desulfurization process, the flow rate of the inert gas when feeding the alloy wire and the aluminum wire during the composition adjustment treatment is 200 to 400 L / min; Preferably, in the refining and desulfurization process, the pressure when feeding the alloy wire and the aluminum wire during the composition adjustment treatment is 0.4-0.5 MPa; Preferably, in the refining and desulfurization process, the flow rate of the inert gas in the post-treatment is 100 to 200 L / min; Preferably, in the refining and desulfurization process, the pressure of the inert gas in the post-treatment is 0.23-0.33 MPa.

8. The semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder according to any one of claims 1 to 7, characterized in that: In the refining without desulfurization process, the flow rate of the inert gas during the arrival of molten steel at the station is 250-350 L / min; Preferably, in the refining without desulfurization process, the pressure of the inert gas during the arrival of molten steel at the station is ≥0.4MPa; Preferably, in the refining without desulfurization process, the flow rate of the inert gas after the shell is broken during the arrival of the molten steel at the station is 20 to 100 L / min; Preferably, in the refining without desulfurization process, the pressure of the inert gas after the shell is broken during the arrival of the molten steel at the station is 0.2-0.25 MPa; Preferably, in the refining without desulfurization process, the flow rate of the inert gas during the temperature adjustment process is 150 to 250 L / min; Preferably, in the refining without desulfurization process, the pressure of the inert gas during the temperature adjustment process is 0.25-0.40 MPa; Preferably, in the refining without desulfurization process, the flow rate of the inert gas during sampling and temperature measurement is 100 to 200 L / min; Preferably, in the refining without desulfurization process, the pressure of the inert gas during sampling and temperature measurement is 0.23-0.35 MPa; Preferably, in the refining without desulfurization process, the flow rate of the inert gas when mixing the carburizer in the composition adjustment process is 600-700 L / min; Preferably, in the refining without desulfurization process, the pressure when mixing the carburizer in the composition adjustment process is 0.55-0.65 MPa; Preferably, in the refining without desulfurization process, the recarburizer is mixed during the composition adjustment process and stirred for 2 to 3 minutes; Preferably, in the refining without desulfurization process, the flow rate of the inert gas when feeding the alloy wire and the aluminum wire during the composition adjustment treatment is 200 to 300 L / min; Preferably, in the refining without desulfurization process, the pressure when feeding the alloy wire and the aluminum wire during the composition adjustment treatment is 0.4-0.5 MPa; Preferably, in the refining without desulfurization process, the flow rate of the inert gas in the post-treatment is 100 to 200 L / min; Preferably, in the refining without desulfurization process, the pressure of the inert gas in the post-treatment is 0.23-0.33 MPa.

9. The semi-molten steel smelting control method for eliminating white spots on a rolling and scraping cylinder according to claim 7 or 8, characterized in that: The inert gas includes any one of argon, nitrogen or helium, or a combination of at least two of them; Preferably, the end point of the refining and desulfurization process is a S content of ≤ 0.002 wt%; Preferably, the end point of the refining without desulfurization process is that the S content is ≤ 0.015wt%.

10. The semi-molten steel smelting control method for eliminating white spots on a rolling scraper cylinder according to any one of claims 1 to 9, characterized in that: The steel types using the refining and desulfurization process include 25Mn or Q235B-1 / 21 / 13; Preferably, the steel type using the refining without desulfurization process includes any one of H345B, 40Mn2 or 27SiMn.

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