High-silicon alloy steel hydrogen control steelmaking smelting method

Abstract

The invention discloses a high-silicon alloy steel hydrogen control steelmaking smelting method, belongs to the technical field of steel smelting, and solves the technical problems of high hydrogen content, long alloy baking time and high-silicon steel hydrogen embrittlement sensitivity in a non-vacuum treatment process in the prior art. According to the high-silicon alloy steel hydrogen control steelmaking smelting method, the processes of converter steelmaking, LF refining and continuous casting machine casting are adopted; the early-stage blowing flow of a converter is controlled, pulverized coal is added for blowing, the early-stage temperature is rapidly increased, the moisture content in raw materials and auxiliary materials is controlled, the raw materials comprise dry waste steel and converter alloy, the converter alloy is turned over through two stock bins, and the converter alloy is baked in advance; the auxiliary materials comprise lime, blast furnace return mine and slagging material drying treatment, the auxiliary materials adopt lime kiln lime with turnover time less than or equal to 48 hours and sintering machine head return mine, and finally, the hydrogen content in the high-silicon alloy steel (Si is greater than or equal to 1.40%) molten steel is stably controlled within 3.0 ppm under the condition that vacuum degassing equipment is not adopted for treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of steel smelting, and in particular to a method for smelting high-silicon alloy steel by controlling hydrogen. Background Art

[0002] Hydrogen dissolved in steel can reduce the steel's plasticity and toughness. If hydrogen is not promptly released during the solidification process, it can form tiny pores in the steel, causing surface defects on the ingot and leading to defects such as white spots and cracks in the rolled product. The presence of white spots has a very negative impact on the steel's performance, reducing its mechanical properties and seriously affecting product quality. This is especially true for high-silicon alloy steels, whose silicon content is typically greater than 1.4%. Their unique composition makes them even more sensitive to hydrogen, making conventional hydrogen content control standards difficult to meet quality requirements.

[0003] Currently, the most effective way to reduce hydrogen content in steelmaking processes is to use vacuum degassing equipment such as VD or RH to keep the hydrogen content at a low level, but this also increases process costs. Therefore, reducing and stabilizing the hydrogen content in molten steel without using vacuum degassing equipment such as VD or RH is a key technology in the steelmaking field.

[0004] Existing patent document patent CN117551839A discloses a refining method for low hydrogen and low nitrogen control of ultra-high alloy steel. Its alloying process uses metallic manganese and the baking time is 17-20h. The baking time is long and the alloy cost is high. Patent CN116004946A adopts the process route of converter steelmaking, CAS refining, and continuous casting to obtain molten steel with a hydrogen content of ≤5ppm. Patent CN116855682A can stably ensure that the hydrogen content in molten steel is within 4ppm by improving the operating process related to converter-refining. Although the above scheme can also ensure that the hydrogen content in ordinary steel meets the standard, for high-silicon alloy steels, there is still a quality impact on steel grades with high hydrogen content requirements. Therefore, how to achieve precise control of the hydrogen content of high-silicon alloy steel without significantly increasing production costs has become a technical problem that needs to be solved urgently in the current steelmaking field. Summary of the Invention

[0005] In response to the shortcomings and deficiencies in the prior art, the present invention provides a hydrogen-controlled smelting method for high-silicon alloy steel, which stably controls the hydrogen content of molten steel to below 3.0 ppm by optimizing the converter blowing process, strictly controlling raw materials and the alloy baking system without using vacuum degassing equipment. The operation process is simple and easy, and solves the technical problems of insufficient hydrogen content control in non-vacuum treatment processes in the prior art, long alloy baking time, and high hydrogen embrittlement sensitivity of high-silicon steel grades.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: The present invention provides a high-silicon alloy steel hydrogen-controlled steelmaking method, wherein the high-silicon alloy steel comprises the following components: C: 0.51%-0.58%, Si: 1.40%-1.60%, Mn: 0.50%-0.80%, P≤0.015%, S≤0.015%, Ni≤0.10%, Cr: 0.50%-0.80%, Cu≤0.08%, Al≤0.003%, Ti≤0.002%, H≤3.0ppm, and the remainder is Fe and unavoidable impurities;

[0007] High silicon alloy steel hydrogen controlled steelmaking adopts converter steelmaking, LF refining and continuous casting process. Among them, by controlling the oxygen flow in the early stage of converter blowing and adding pulverized coal to blow, the early stage temperature is quickly increased.

[0008] Control the moisture content in raw materials and auxiliary materials, including:

[0009] The raw materials include dry scrap steel and converter alloy. The converter alloy is circulated in two silos and is baked in advance.

[0010] Auxiliary materials include lime, blast furnace return ore and slag drying;

[0011] Finally, without vacuum degassing, the hydrogen content in molten high silicon alloy steel (Si≥1.40%) was controlled within 3.0 ppm.

[0012] Preferably, in the process of high silicon alloy steel hydrogen controlled steelmaking, the specific control of each process step is as follows:

[0013] (1) Preparation and pretreatment: Use a normal turnover hot ladle, control the drying of scrap steel entering the furnace, control the drying of auxiliary materials entering the furnace in advance, and bake the converter alloy in advance;

[0014] (2) Converter blowing: Control the early blowing flow rate, add pulverized coal in the early stage and use a large flow rate to quickly increase the early temperature of the molten pool to reduce the amount of process auxiliary materials such as lime, blast furnace return ore and slag material added; add materials in batches during the blowing process, and adjust the temperature appropriately by adding blast furnace return ore and lime in the middle and late stages of the blowing process according to temperature requirements;

[0015] (3) Alloying of steel: In the early stage of steel tapping, the converter alloy after baking treatment is added in sequence, and the carburizer is added in the later stage of steel tapping. After the steel tapping is completed, refined slag is added into the ladle;

[0016] (4) LF refining: Wollastonite is added to the refining station. No additional slag material is added during the refining process. The remaining components are adjusted by alloying the molten steel. The total amount of refined alloy added is controlled to be ≤300kg / furnace;

[0017] (5) Continuous casting: After the soft blowing of the LF refining furnace is completed and the continuous casting machine is hung for casting, the billet is put into the pit for slow cooling.

[0018] Preferably, in step (1), the control requirements for raw materials and auxiliary materials during the preparation of hydrogen-controlled raw materials are:

[0019] The raw material ladle adopts a normal turnover hot ladle, and the scrap steel is ensured to be surface dry before entering the furnace;

[0020] The auxiliary materials include lime and blast furnace return ore. The lime is lime from a lime kiln with a turnover time of ≤48h. The blast furnace return ore is operated in advance and uses freshly produced sintering machine head material. The water content of the blast furnace return ore is ≤0.3%.

[0021] Preferably, in step (3), the converter alloy includes ferrosilicon, high carbon ferromanganese, and high carbon ferrochromium.

[0022] The converter alloy is baked in advance to remove moisture. The specific alloy baking temperature is ≥120℃ and the baking time is ≥4h.

[0023] Preferably, the converter alloy uses a double silo turnover.

[0024] Preferably, in step (2), the converter blowing process is as follows: first, dry scrap steel and molten iron are added, pulverized coal is added in the early stage of blowing, and the oxygen flow rate is 26000m 3 A large flow rate of / h quickly increases the early temperature. During the blowing process, lime and blast furnace return ore are added in two batches:

[0025] The first batch of lime and blast furnace return ore should be added within the first 6 minutes of the blowing process; the second batch of lime and blast furnace return ore should be added within 7-10 minutes of the blowing process. Later, lime and blast furnace return ore should be added according to temperature requirements to adjust the temperature and ensure that the final temperature target is above 1610℃.

[0026] Preferably, during the converter smelting process, the amount of scrap steel added is 20% of the mass of the molten iron.

[0027] Preferably, in step (3), ferrosilicon, high carbon ferromanganese and high carbon ferrochrome are added in sequence starting from 20t of steel tapping; a recarburizer is added after 70t of steel tapping, and 1t of refined slag is added to the ladle after steel tapping is completed.

[0028] Preferably, the water content of the recarburizer is ≤0.05%.

[0029] Preferably, in step (4), after refining is completed, the molten steel needs to be hydrogenated, and after soft blowing treatment, it is hoisted to the continuous casting machine for casting.

[0030] The present invention provides a high silicon alloy steel hydrogen controlled steelmaking method. It has the following beneficial effects:

[0031] (1) The high silicon alloy steel hydrogen controlled steelmaking method of the present invention controls the moisture content in the raw and auxiliary materials through alloy baking technology to block the hydrogen source, optimizes the converter blowing process to use coal powder to quickly increase the temperature to shorten the hydrogen absorption window, and accurately controls the addition time of the auxiliary materials. While ensuring the efficient utilization of alloy elements, it effectively inhibits the absorption of hydrogen gas and reduces the introduction of moisture. The hydrogen content of the high silicon alloy steel (Si≥1.40%) molten steel is stably controlled to be below 3.0ppm under the condition of not using vacuum treatment.

[0032] (2) The present invention is aimed at the steelmaking and smelting of high-silicon alloy steel (Si≥1.40%), and adopts an innovative converter alloy baking treatment technology to shorten the treatment time by more than 12 hours compared with the traditional process. The double-bin turnover system is used to significantly improve the batching efficiency, and combined with the precise control of the auxiliary material addition time, the above multiple processes are coordinated and optimized, which ensures that the hydrogen content of the molten steel of the high-silicon alloy steel is stably controlled at an ultra-low level while significantly improving the production efficiency and effectively reducing the overall production cost. It effectively solves the current industry problems of high-silicon alloy steel grades that are not up to standard in hydrogen content control accuracy under non-vacuum treatment processes, long alloy baking time, high hydrogen embrittlement sensitivity of high-silicon steel grades, and high production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a diagram of hydrogen determination data before the continuous casting process in Example 1 of the present invention;

[0034] Figure 2 This is a diagram of hydrogen determination data before the continuous casting process in Example 2 of the present invention. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0036] The high-silicon alloy steel hydrogen-controlled steelmaking method of the present invention adopts the process of smelting high-silicon alloy steel 55SiCr, whose chemical composition includes C: 0.51%-0.58%, Si: 1.40%-1.60%, Mn: 0.50%-0.80%, P≤0.015%, S≤0.015%, Ni≤0.10%, Cr: 0.50%-0.80%, Cu≤0.08%, Al≤0.003%, Ti≤0.002%, H≤3.0ppm, and the rest is Fe and unavoidable impurities. The high-silicon alloy steel is smelted by the process of converter steelmaking, LF refining, and continuous casting machine casting. For the sake of clarity, the following examples are used to describe the detailed description.

[0037] Example 1

[0038] The high silicon alloy steel hydrogen controlled steelmaking method comprises the following steps:

[0039] (1) Preparation and pretreatment of raw and auxiliary materials: Confirm that the ladle is a normal turnover hot ladle, and the raw material is dry scrap steel. The surface must be dry before entering the furnace; the converter alloy uses two silos for turnover and is baked in advance to remove moisture. The specific alloy baking temperature is 298℃ and the baking time is 6.5h.

[0040] Auxiliary materials include lime, blast furnace return ore and slag drying process. Lime uses lime from a lime kiln with a turnover time of ≤48h to ensure that the limestone is dry and free of moisture. Blast furnace return ore is operated in advance using freshly produced sintering machine head material, and the moisture content of blast furnace return ore is ≤0.3%.

[0041] (2) Converter smelting: First, add 24.9t of dry scrap steel and 99t of molten iron. Add 1.2t of pulverized coal before blowing. Set the oxygen flow rate at the early stage of blowing to 26000m 3 / h, using a large flow rate for ignition blowing to quickly increase the early temperature, reduce the amount of slag materials such as lime and blast furnace return ore added during the process, and reduce the introduction of moisture;

[0042] During the blowing process, lime and blast furnace return ore were added in two batches; the first batch of materials was completed in 5 minutes and 13 seconds with 18.54 kg of lime per ton of steel and 10.23 kg of blast furnace return ore per ton of steel; the second batch of materials was completed in 9 minutes and 41 seconds with 3.5 kg of lime per ton of steel and 2.2 kg of blast furnace return ore per ton of steel; during the converter smelting process, when the second batch of furnace charges was added, the temperature measuring system detected that the molten pool temperature was 1575°C. No slag-forming materials such as lime and blast furnace return ore were added in the later stage, and the terminal temperature of the converter smelting was 1612°C.

[0043] (3) Alloying of steel: The alloying process begins when 20 tons of steel are tapped. 20.98 kg of ferrosilicon per ton of steel, 7.5 kg of high carbon ferromanganese per ton of steel, and 10.0 kg of high carbon ferrochromium per ton of steel are added in sequence. The baking temperature of the converter alloy is 298 °C. When the tapping volume reaches 70 tons, 3.0 kg of recarburizer per ton of steel is added. After tapping, 1 ton of refined slag is added into the ladle for off-furnace refining.

[0044] (4) LF refining: add 200kg of wollastonite into the refining station, use alloying agent to add 1.0kg of ferrosilicon per ton of steel, 0.4kg of high carbon ferromanganese per ton of steel, and 0.5kg of high carbon ferrochrome per ton of steel. After refining, carry out hydrogen determination operation on molten steel, such as Figure 1 As shown, the hydrogen concentration is set at 2.5ppm before soft blowing. After the soft blowing is completed, the steel is hoisted to the continuous casting machine for casting, and the ingot is put into the pit for slow cooling.

[0045] Example 2

[0046] The high silicon alloy steel hydrogen controlled steelmaking method comprises the following steps:

[0047] (1) Preparation and pretreatment of raw and auxiliary materials: Confirm that the ladle is a normal turnover hot ladle, and the raw material is dry scrap steel. The surface must be dry before entering the furnace; the converter alloy uses two silos for turnover and is baked in advance to remove moisture. The specific alloy baking temperature is 298℃ and the baking time is 6.5h.

[0048] Auxiliary materials include lime, blast furnace return ore and slag drying process. Lime uses lime from a lime kiln with a turnover time of ≤48h to ensure that the limestone is dry and free of moisture. Blast furnace return ore is operated in advance using freshly produced sintering machine head material, and the moisture content of blast furnace return ore is ≤0.3%.

[0049] (2) Converter smelting: First, add 25.16t of dry scrap steel and 98.7t of molten iron. Add 1.2t of pulverized coal before blowing. Set the oxygen flow rate at the early stage of blowing to 26000m 3 / h, using a large flow rate for ignition blowing to quickly increase the early temperature, reduce the amount of slag materials such as lime and blast furnace return ore added during the process, and reduce the introduction of moisture;

[0050] During the blowing process, lime and blast furnace return ore were added in two batches; the first batch of materials was completed in 5 minutes and 52 seconds with 18.36 kg of lime per ton of steel and 9.53 kg of blast furnace return ore per ton of steel; the second batch of materials was completed in 9 minutes and 22 seconds with 3.1 kg of lime per ton of steel and 2.9 kg of blast furnace return ore per ton of steel; during the converter smelting process, when the second batch of furnace charges was added, the temperature measuring system detected that the molten pool temperature was 1570°C, and later in 11 minutes and 30 seconds, an additional 1.3 kg of lime per ton of steel was added, and the terminal temperature of the converter smelting was 1614°C.

[0051] (3) Alloying of steel: The alloying process begins when 20 tons of steel are tapped. 20.05 kg of ferrosilicon per ton of steel, 7.3 kg of high carbon ferromanganese per ton of steel, and 9.8 kg of high carbon ferrochrome per ton of steel are added in sequence. The baking temperature of the converter alloy is 265°C. When the tapping volume reaches 70 tons, 3.0 kg of recarburizer per ton of steel is added. After tapping, 1 ton of refined slag is added into the ladle for off-furnace refining.

[0052] (4) LF refining: add 200kg of wollastonite into the refining station, use alloying agent to add 1.02kg of ferrosilicon per ton of steel, 0.55kg of high carbon ferromanganese per ton of steel, and 0.72kg of high carbon ferrochrome per ton of steel. After refining, carry out hydrogen determination operation on molten steel, such as Figure 2 As shown, the hydrogen concentration was set at 2.7ppm before soft blowing. After the soft blowing was completed, the steel was hoisted to the continuous casting machine for casting, and the ingot was put into the pit for slow cooling.

[0053] In summary, the high silicon alloy steel controlled hydrogen steelmaking method of the present invention controls the moisture content in the raw and auxiliary materials by alloy baking technology to block the hydrogen source, optimizes the converter blowing process to use coal powder to quickly raise the temperature to shorten the hydrogen absorption window, accurately controls the addition time of auxiliary materials, effectively inhibits hydrogen gas absorption while ensuring the efficient utilization of alloy elements, reduces the introduction of moisture, and makes the high silicon alloy steel steelmaking process stable under the condition of not using vacuum treatment. The hydrogen content of high silicon alloy steel molten steel is controlled to below 3.0ppm. At the same time, the innovative converter alloy baking treatment technology is adopted to shorten the treatment time by more than 12h compared with the traditional process, and the double silo turnover system is used to significantly improve the batching efficiency, and combined with the precise control of the auxiliary material addition time, the above multiple processes are coordinated and optimized, while ensuring that the hydrogen content of high silicon alloy steel molten steel is stably controlled at an ultra-low level, the production efficiency is significantly improved and the comprehensive production cost is effectively reduced, solving the technical problems of the industry problems of insufficient hydrogen content control in the non-vacuum treatment process in the prior art, the difficulty of combined hydrogen control, the long gold baking time, the high hydrogen embrittlement sensitivity of high silicon steel and the high production cost.

[0054] On the basis of the above embodiments, the present invention continues to describe in detail the technical features involved therein and the functions and roles played by the technical features in the present invention, so as to help technicians in this field fully understand the technical solutions of the present invention and reproduce them.

[0055] Finally, although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A high silicon alloy steel hydrogen controlled steelmaking method, characterized in that: The high silicon alloy steel comprises the following components: C: 0.51%-0.58%, Si: 1.40%-1.60%, Mn: 0.50%-0.80%, P≤0.015%, S≤0.015%, Ni≤0.10%, Cr: 0.50%-0.80%, Cu≤0.08%, Al≤0.003%, Ti≤0.002%, H≤3.0ppm, and the remainder is Fe and unavoidable impurities; The high silicon alloy steel hydrogen controlled steelmaking process adopts converter steelmaking, LF refining and continuous casting process, wherein the oxygen flow rate in the early stage of converter blowing is controlled and coal powder is added for blowing to quickly increase the early stage temperature. Control the moisture content in raw materials and auxiliary materials, including: The raw materials include dry scrap steel and converter alloy. The converter alloy is circulated in two silos and is baked in advance. Auxiliary materials include lime, blast furnace return ore and slag drying; Finally, without vacuum degassing, the hydrogen content in molten high silicon alloy steel (Si≥1.40%) was controlled within 3.0 ppm.

2. The high silicon alloy steel hydrogen controlled steelmaking method according to claim 1, characterized in that: In the process of high silicon alloy steel hydrogen controlled steelmaking, the specific control of each process step is as follows: (1) Preparation and pretreatment: Use a normal turnover hot ladle, control the drying of scrap steel entering the furnace, control the drying of auxiliary materials entering the furnace in advance, and bake the converter alloy in advance; (2) Converter blowing: Control the oxygen flow rate in the early stage of converter blowing, add pulverized coal and use high-flow blowing to quickly increase the temperature of the molten pool in the early stage, so as to reduce the amount of lime, blast furnace return ore and slag material added as auxiliary materials in the process; add materials in batches during the blowing process, and adjust the temperature appropriately by adding blast furnace return ore and lime in the middle and late stages of blowing according to temperature requirements; (3) Alloying of steel: In the early stage of steel tapping, the converter alloy after baking treatment is added in sequence, and the carburizer is added in the later stage of steel tapping. After the steel tapping is completed, refined slag is added into the ladle; (4) LF refining: Wollastonite is added to the refining station. No additional slag material is added during the refining process. The remaining components are adjusted by alloying the molten steel. The total amount of refined alloy added is controlled to be ≤300kg / furnace; (5) Continuous casting: After the soft blowing of the LF refining furnace is completed and the continuous casting machine is hung for casting, the billet is put into the pit for slow cooling.

3. The high silicon alloy steel hydrogen controlled steelmaking method according to claim 2, characterized in that: In step (1), the control requirements for raw materials and auxiliary materials during the preparation of hydrogen control raw materials are as follows: The raw material ladle adopts a normal turnover hot ladle, and the scrap steel is ensured to be surface dry before entering the furnace; The auxiliary materials include lime and blast furnace return ore. The lime is lime from a lime kiln with a turnover time of ≤48h. The blast furnace return ore is operated in advance and uses freshly produced sintering machine head material. The water content of the blast furnace return ore is ≤0.3%.

4. The high silicon alloy steel hydrogen controlled steelmaking method according to claim 2, characterized in that: In step (3), the converter alloy includes ferrosilicon, high carbon ferromanganese, and high carbon ferrochromium. The converter alloy is baked in advance to remove moisture. The specific alloy baking temperature is ≥120℃ and the baking time is ≥4h.

5. A high silicon alloy steel hydrogen controlled steelmaking method according to claim 4, characterized in that: The converter alloy uses a double silo turnover.

6. The high silicon alloy steel hydrogen controlled steelmaking method according to claim 2, characterized in that: In step (2), the converter blowing process is as follows: first, add dry scrap steel and molten iron, add pulverized coal in the early stage of blowing and use an oxygen flow rate of 26000m 3 A large flow rate of / h quickly increases the early temperature. During the blowing process, lime and blast furnace return ore are added in two batches: The first batch of lime and blast furnace return ore should be added within the first 6 minutes of the blowing process; the second batch of lime and blast furnace return ore should be added within 7-10 minutes of the blowing process. Later, lime and blast furnace return ore should be added according to temperature requirements to adjust the temperature and ensure that the final temperature target is above 1610℃.

7. The high silicon alloy steel hydrogen controlled steelmaking method according to claim 6, characterized in that: During the converter smelting process, the amount of scrap steel added is 20% of the mass of the molten iron.

8. The method for smelting high silicon alloy steel by controlling hydrogen according to claim 2, characterized in that: In step (3), ferrosilicon, high carbon ferromanganese and high carbon ferrochrome are added in sequence starting from 20t of steel tapping; recarburizer is added after 70t of steel tapping, and 1t of refined slag is added to the ladle after steel tapping is completed.

9. The high silicon alloy steel hydrogen controlled steelmaking method according to claim 8, characterized in that: The water content of the recarburizer is ≤0.05%.

10. The method for smelting high silicon alloy steel by controlling hydrogen according to claim 2, characterized in that: In step (4), after refining is completed, the molten steel needs to be hydrogenated, and after soft blowing treatment, it is hoisted to the continuous casting machine for casting.

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