Smelting method of steel for loading machinery
Through the use of iron dregs and limestone residue technology in the smelting process to optimize the smelting conditions, the problem of insufficient mechanical steel performance in existing technologies and high smelting costs were successfully prepared. Switching costs.
Patent Information
- Application Number
- CN202411429827.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-14
- Publication Date
- 2025-01-24
AI Technical Summary
It is difficult to prepare mechanical steel with high yield strength and tensile strength in the prior art, and low-cost smelting technology has not yet achieved the goal of low cost and high quality.
Using desulfurization, converter smelting, LF refining, RH refining and continuous casting processes, through the iron slag forming route and limestone slag making process, the f-CaO content of the final slag of high basicity steel slag is controlled, the MgO ratio is increased, and the oxygen supply is reduced quantity and optimize smelting conditions to improve the performance of steel.
Preparing mechanical steel with yield strength Rel≥345Mpa and tensile strength Rm≥470Mpa reduces smelting costs and improves the market competitiveness of the product.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of steel smelting, and in particular relates to a method for smelting steel for loader machinery. Background Art
[0002] The main structural parts of construction machinery are subjected to complex and variable cyclic loads, requiring their component materials to have high yield strength and fatigue strength, good impact toughness, cold forming and excellent weldability. As construction machinery develops towards large-scale and lightweight, the requirements for the above performance are more prominent. The performance level of high-strength steel plates plays an important role in improving the capacity and efficiency of construction machinery, extending its service life, reducing the weight of equipment, reducing energy consumption, and improving the grade of the entire machine.
[0003] As competition intensifies, resource utilization has become the mainstream trend for reducing costs and improving efficiency. Low-cost, high-quality smelting technology has become the current direction of technical research. Faced with complex and severe operating conditions and environmental protection innovation, low-cost control of the steel industry has become an inevitable choice for survival and continuation. Therefore, it is necessary to develop a low-cost and high-performance mechanical steel to improve the market competitiveness of the product. Summary of the invention
[0004] The object of the present invention is to provide a smelting method for mechanical steel for a loader, wherein the mechanical steel prepared by the method has a lower yield strength Rel (Mpa) ≥ 345 and a tensile strength Rm (Mpa) ≥ 470.
[0005] To achieve the above purpose, the technical solution of the present invention is as follows:
[0006] A smelting method for loader mechanical steel includes desulfurization, converter smelting, LF refining, RH refining and continuous casting processes.
[0007] Furthermore, the converter smelting of the present invention adopts an iron slag forming route, lime, limestone, and lightly burned dolomite are used for slag forming in the early stage of smelting, and after the CO2 of limestone is decomposed by heat, it can react with [Fe], [Si], [Mn], [C], etc. to produce an oxidation reaction, which plays a good role in fluxing and stirring, and meets the relevant conditions of low-temperature and high-basicity dephosphorization of the converter. In order to improve the activity of steelmaking lime and limestone, 2 to 3 tons of magnetic separation slag under the furnace is quantitatively proportioned per furnace, so that the initial slag formation time can be advanced by 1 to 2 minutes, which is conducive to the stable control of the blowing process and the reduction of molten steel overoxidation, and the slag forming process of adding lime to reduce the basicity is adopted to effectively control the final slag f-CaO content of high-basicity slag; in addition, the slag retention operation of the previous furnace is used to increase the MgO ratio in the early stage of blowing, and the MgO content is basically saturated, which can not only accelerate the rapid formation of the initial slag, but also slow down the erosion of the initial slag on the furnace lining and increase the service life of the converter.
[0008] Furthermore, the converter smelting of the present invention: the furnace S is less than or equal to 0.020%, a high gun position and low oxygen pressure are adopted, the gun position is controlled at 1.5 to 1.8 meters, and the oxygen pressure is controlled at 0.6 to 0.7 MPa; the blowing is started within 2 to 3 minutes, and the oxygen flow rate is 24000 to 26000 Nm 3 / h, so that it has sufficient time to melt, laying a good foundation for the early slag in the early stage of smelting, and playing a vital role in the early dephosphorization; in the middle stage of blowing, in order to reduce and avoid metal splashing caused by drying, the lance is raised in advance during the drying period, and a small amount of ore is added to eliminate drying. The oxygen lance position of the process smelting is controlled at 1.4-1.5 meters, the oxygen pressure is 0.7-0.9Mpa, and the oxygen flow rate is 32000-38000Nm 3 / h, determine the slagging situation and blowing state according to the flame state and the sound in the furnace, adjust the gun position and the addition of cold material in time, and control the blowing smoothly; add part of the carbon powder for gasification and deoxidation according to the oxygen content of the molten steel at the end point, improve the alloy yield of the molten steel and reduce the smelting cost; the end point temperature of the first converter is 1645-1615℃, and the continuous pulling temperature is 1620-1640℃. The converter end point is controlled to be C≥0.06%, P≤0.015%, S≤0.015%.
[0009] Furthermore, the converter smelting of the present invention: 300-500 kg of lime and 200-350 kg of refined slag are added to the ladle slag after steel tapping; the argon station adjusts the argon flow rate to 1000-1500 NL / min, blows argon for 3-5 minutes to fully stir and modify the slag, and the slag washing process has a diffusion deoxidation function, which can effectively reduce the FeO content in the slag. At the same time, the changes in various components in the slag have a certain modification effect on the ladle slag, which can reduce the erosion of the steel slag on the tank lining. Since the slag contains a certain amount of metal, it oxidizes and generates heat during the slag washing process, which has the function of compensating the temperature drop of the molten steel and plays a thermal compensation function. At the same time, the deoxidation is moved forward to assist deoxidation and desulfurization. The liquid product after slag washing covers the surface of the molten steel, which can play a good role in heat preservation and prevention of secondary oxidation, reduce the LF refining deoxidation time, and shorten the smelting cycle.
[0010] Further, the LF refining of the present invention: set the argon flow rate ≤ 1500NL / min, add slag-making materials in multiple batches and small batches according to the permeability of the ladle to prevent the appearance of large pieces of raw slag; fully melt the slag material to avoid incomplete melting of the material pile and uneven slag roll carbon powder, and it is strictly forbidden to add carbon powder in the early stage; according to the chemical sample of the previous process, reasonably prepare the slag to ensure the slag alkalinity, viscosity, and slag amount, add lime after adding deoxidizer and slag material, and add 1000-1300kg of lime in batches before heating once, and each batch ≤ 800kg; after adding the materials, stir and melt them fully, and heat them. In the early stage of electrode heating, long arc heating is used to heat the slag, and short arc + foam slag operation is used to heat quickly in the later stage. After the end of the heating once, adjust the argon gas to 800-1500NL / min for deoxidation and desulfurization operations. Observe the color and state of the sticky slag, add deoxidizer and slag agent in time, and deep deoxidation forms white slag during the strong stirring of argon gas. The thickness of the sticky slag is preferably 1.5-3mm, and alloying is performed. Adjust the argon gas to 200-300NL / min to stir and even out the temperature and composition. When measuring temperature and sampling, water cooling is prohibited to avoid cracks in the sample and make it unrepresentative. According to the chemical sample, all chemical components are added to meet the process requirements. After refining, [O]≤10ppm, [N]≤40ppm, and then hoisted to the RH furnace for processing.
[0011] Furthermore, the RH refining process of the present invention: top gun baking operation is performed before smelting treatment. Before smelting this steel grade, two furnaces of low-carbon steel are used to wash the tank, clean the cold steel in the tank, reduce the alloy burning loss of RH treated steel liquid, and improve the alloy recovery rate. Confirm that the vacuum tank immersion pipe circulation pipe is well permeable, the gun position is 6.0-4.5m, and the flow rate is 180-220Nm 3 / h, start 4a pump pre-vacuum before smelting operation to save smelting cycle, adjust the circulating argon gas to 70~100Nm 3 / h, control degassing for 15 to 20 minutes to carry out molten steel circulation treatment, the circulation of molten steel in the vacuum tank begins, according to the chemical sample steel of the previous process, add Taiwan aluminum to adjust to the upper limit of the target ALs content, circulate for 3 to 6 minutes, perform the ALs content operation of the oxygen meter, and perform alloying fine-tuning when it meets the upper limit of the target ALs content, add titanium iron to adjust the alloy composition to the target range at one time; keep the vacuum degree ≤100Pa, pure degassing time
[0012] ≥8min, after the treatment, calcium treatment is completed at 200-400m / furnace, and it is allowed to stand for 15-20min; RH first furnace tapping temperature: 1590-1600℃, continuous pulling temperature: 1570-1580℃.
[0013] Furthermore, the chemical composition of the mechanical steel described in the present invention is calculated by weight percentage as follows: C 0.28-0.31%, Si 0.30-0.40%, Mn 1.35-1.45%, P≤0.015%, S≤0.005%, B 0.0030-0.0050%, Ti0.03-0.05%, Mo 0.05-0.10%, Cr 0.40-0.60%, Cu 0.05-0.10%, Ni 0.016-0.026%, Als 0.015-0.050%, [O]≤10ppm, [N]≤40ppm, and the remainder is Fe and unavoidable impurities.
[0014] Furthermore, the mechanical steel obtained by the method of the present invention has a lower yield strength Rel (Mpa) ≥ 345 and a tensile strength Rm (Mpa) ≥ 470.
[0015] The inventive principle and beneficial effects of the technical solution of the present invention are:
[0016] The converter adopts the iron slag formation route. In order to improve the activity of steelmaking lime and limestone, the magnetic separation slag under the furnace is quantitatively proportioned to 2-3 tons / furnace, and the self-produced steel slag surface and slag-making materials with components such as MnO, Al2O3 and SiO2 are increased. The MgO and MnO in the slag are used to expand the liquid phase, promote the melting of lime, and advance the initial slag formation time by 1-2 minutes. The slag drying phenomenon in the process can be improved; and the slag-making process of adding lime to reduce the alkalinity is adopted to effectively control the final slag f-CaO content of high-alkalinity steel slag, and the lime consumption is reduced by 5-8kg / t. The slag retention operation of the previous furnace is used to increase the MgO ratio, accelerate the rapid formation of the initial slag, and effectively reduce the oxygen supply. The oxidizability of the molten steel is effectively controlled, with an average reduction of 100-250ppm, and the amount of deoxidizer added can be reduced by 30-75kg / furnace, reducing the smelting cost.
[0017] The high gun position and low oxygen pressure allow sufficient time for melting, laying a good foundation for early slag melting in the early stage of smelting, and playing a vital role in early dephosphorization; at the same time, the application of limestone can reduce the cost of converter steelmaking, reduce the impact of active lime supply interruption on production, achieve the purpose of carbon dioxide emission reduction, and increase the added value of products. The argon station slag washing and deoxidation are moved forward to assist deoxidation and desulfurization; the liquid product after slag washing covers the surface of the molten steel, which can play a good role in heat preservation and prevention of secondary oxidation, reduce the LF refining deoxidation time, and shorten the smelting cycle. DETAILED DESCRIPTION
[0018] The technical solution of the present invention is further described in detail below in conjunction with embodiments.
[0019] Examples 1-6
[0020] A smelting method for loader mechanical steel, characterized by comprising desulfurization, converter smelting, LF refining, RH refining and continuous casting; the details are as follows:
[0021] (1) Converter smelting: The iron slag forming route is adopted. In the early stage of smelting, lime, limestone and light-burned dolomite are used to make slag. 2 to 3 tons of magnetic separation slag is quantitatively mixed per furnace, and slag retention operation is performed.
[0022] S in the furnace is ≤0.020%, high gun position and low oxygen pressure are adopted, the gun position is controlled at 1.5-1.8 meters, and the oxygen pressure is controlled at 0.6-0.7Mpa; within 2-3 minutes of blowing, the oxygen flow rate is 24000-26000Nm 3 / h; in the middle stage of blowing, the oxygen lance position is controlled at 1.4-1.5 meters, the oxygen pressure is 0.7-0.9Mpa, and the oxygen flow rate is 32000-38000Nm 3 / h, the first converter end point temperature is 1645-1615℃, the continuous pulling temperature is 1620-1640℃, the converter end point control C≥0.06%, P≤0.015%, S≤0.015%.
[0023] After steel tapping is completed, 300-500 kg / furnace of lime and 200-350 kg / furnace of refined slag are added to the ladle slag; the argon station adjusts the argon flow rate to 1000-1500 NL / min, and blows argon for 3-5 minutes.
[0024] The control parameters of the converter steelmaking process in each embodiment are shown in Table 1 and Table 2 respectively.
[0025] Table 1 Example 1-6 Converter Steelmaking Process Parameters 1
[0026]
[0027] Table 2 Example 1-6 Converter Steelmaking Process Parameters 2
[0028]
[0029]
[0030] (2) LF refining: set the argon flow rate to ≤1500NL / min, add slag-making materials in multiple batches or small batches according to the permeability of the ladle, and it is strictly forbidden to add carbon powder in the early stage; add lime after adding deoxidizer and slag-forming materials, and add 1000-1300kg of lime in batches before heating once, and each batch is ≤800kg; stir and melt the materials after adding, and heat them. In the early stage of electrode heating, long arc heating is used to melt the slag, and short arc + foam slag operation is used to heat quickly in the later stage. After the first heating is completed, adjust the argon to 800-1500NL / min for deoxidation and desulfurization operations; control the thickness of sticky slag to 1.5-3mm; adjust the argon to 200-300NL / min; after refining, [O]≤10ppm, [N]≤40ppm, and hoist it to the RH furnace for treatment. The refining process parameters of each embodiment are shown in Table 3.
[0031] Table 3 Parameters of LF refining process in Examples 1-6
[0032]
[0033] (3) RH refining process: Top gun baking operation is carried out before smelting treatment; confirm that the vacuum tank immersion pipe circulation pipe is well permeable, the gun position is 6.0~4.5m, and the flow rate is 180~220Nm 3 / h, before the smelting treatment operation, the 4a pump pre-vacuum is turned on to save the smelting cycle, the circulating argon is adjusted to 70-100Nm3 / h, and the degassing is controlled for 15-20min to carry out the molten steel circulation treatment. The molten steel circulation in the vacuum tank begins, and the target ALs content Als 0.015-0.050% upper limit is added to the chemical sample steel of the previous process, and the circulation is 3-6min, and the ALs content of the oxygen meter is operated. The alloying fine adjustment is carried out when it meets the upper limit of the target ALs content, and titanium iron is added to adjust the alloy composition to the target range at one time; the vacuum degree is maintained at ≤100Pa, and the pure degassing time is ≥8min. After the treatment, the calcium treatment is completed at 200-400m / furnace, and it is left to stand for 15-20min; the RH first furnace tapping temperature: 1590-1600℃, and the continuous pulling temperature: 1570-1580℃. The control parameters of the RH refining process of each embodiment are shown in Table 4.
[0034] Table 4 RH refining process parameters for Examples 1-6
[0035]
[0036]
[0037] The chemical composition and mass percentage of the loader mechanical steel in each embodiment are shown in Table 6.
[0038] Table 6 Chemical composition and mass percentage of molten steel in Example 1-6 (%)
[0039]
[0040] In Table 6, the remainder is Fe and unavoidable impurities.
[0041] The mechanical properties of the continuous casting slabs obtained in each embodiment after hot rolling are shown in Table 7.
[0042] Table 7 Mechanical properties of continuous casting slabs after hot rolling in various embodiments
[0043]
[0044] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A method for smelting steel for loader machinery, characterized in that: Including desulfurization, converter smelting, LF refining, RH refining and continuous casting.
2. The smelting method of a loader mechanical steel according to claim 1, characterized in that: The converter smelting adopts an iron slag forming route, lime, limestone and light-burned dolomite are used for slag forming in the early stage of smelting, 2 to 3 tons of magnetic separation slag is quantitatively mixed per furnace, and slag retention operation is performed.
3. The smelting method of a loader mechanical steel according to claim 1, characterized in that: The converter smelting: S≤0.020% in the furnace, high lance position and low oxygen pressure, the lance position is controlled at 1.5-1.8 meters, the oxygen pressure is controlled at 0.6-0.7Mpa; the blowing is started within 2-3 minutes, and the oxygen flow rate is 24000-26000Nm 3 / h; in the middle stage of blowing, the oxygen lance position is controlled at 1.4-1.5 meters, the oxygen pressure is 0.7-0.9Mpa, the oxygen flow rate is 32000-38000N / h, the first furnace end temperature of the converter is 1645-1615℃, the continuous pulling temperature is 1620-1640℃, and the converter end point is controlled at C≥0.06%, P≤0.015%, and S≤0.015%.
4. The smelting method of a loader mechanical steel according to claim 1, characterized in that: The converter smelting: after the steel is tapped, 300-500 kg of lime and 200-350 kg of refined slag are added to the ladle slag; the argon station adjusts the argon flow rate to 1000-1500 NL / min, and blows argon for 3-5 minutes.
5. The smelting method of a loader mechanical steel according to claim 1, characterized in that: The LF refining: set the argon flow rate ≤1500NL / min, add slag-making materials in multiple batches or small batches according to the permeability of the ladle, and it is strictly forbidden to add carbon powder in the early stage; add lime after adding deoxidizer and slag-forming material, and add 1000-1300kg of lime in batches before the first heating, and each batch ≤800kg; after the addition is completed, stir and melt fully, and heat treatment is carried out. In the early stage of electrode heating, long arc heating is used to melt the slag, and short arc + foam slag operation is used for rapid heating in the later stage. After the first heating is completed, adjust the argon to 800-1500NL / min for deoxidation and desulfurization operations; control the thickness of sticky slag to 1.5-3mm; adjust the argon to 200-300NL / min; after refining, [O]≤10ppm, [N]≤40ppm, and hoist it to the RH furnace for treatment.
6. The smelting method of a loader mechanical steel according to claim 1, characterized in that: The RH refining process: top gun baking operation is performed before smelting treatment; confirm that the vacuum tank immersion pipe circulation pipe is well ventilated, the gun position is 6.0-4.5m, and the flow rate is 180-220Nm 3 / h, start 4a pump pre-vacuum before smelting operation to save smelting cycle, adjust the circulating argon gas to 70~100Nm 3 / h, control degassing for 15-20min to carry out molten steel circulation treatment, the molten steel circulation in the vacuum tank begins, according to the chemical sample steel of the previous process, add Taiwan aluminum to adjust to the upper limit of the target ALs content and circulate for 3-6min, perform the ALs content operation of the oxygen meter, and perform alloying fine-tuning when it meets the upper limit of the target ALs content, and add titanium iron to adjust the alloy composition to the target range at one time; maintain the vacuum degree ≤100Pa, the pure degassing time ≥8min, and after the treatment, the calcium treatment is completed for 200-400m / furnace and let it stand for 15-20min; RH first furnace tapping temperature: 1590~1600℃, continuous pulling temperature: 1570~1580℃.
7. The smelting method of a loader mechanical steel according to claim 1, characterized in that: The chemical composition of the mechanical steel is as follows by weight percentage: C 0.28-0.31%, Si 0.30-0.40%, Mn 1.35-1.45%, P≤0.015%, S≤0.005%, B 0.0030-0.0050%, Ti 0.03-0.05%, Mo 0.05-0.10%, Cr 0.40-0.60%, Cu 0.05-0.10%, Ni 0.016-0.026%, Als 0.015-0.050%, [O]≤10ppm, [N]≤40ppm, and the remainder is Fe and unavoidable impurities.
8. The smelting method of a loader mechanical steel according to claim 1, characterized in that: The mechanical steel obtained by the method has a lower yield strength Rel (Mpa) ≥ 345 and a tensile strength Rm (Mpa) ≥ 470.