A long-life wear-resistant steel S650A and its manufacturing method

Abstract

This invention discloses a long-life wear-resistant media steel S650A and its manufacturing method. The main chemical components of this wear-resistant media steel are C: 0.75%~0.85%, Si: 0.15%~0.40%, Mn: 1.00%~1.10%, Cr: 1.00%~1.10%, Mo: 0.06%~0.10%, Al: 0.015%~0.030%, N: 0.0045%~0.0100%, etc. The wear-resistant media S650A is produced by "ecological electric furnace smelting + LF furnace refining + RH vacuum treatment + continuous casting + 1150BD continuous rolling mill". This method can effectively improve the service life of wear-resistant media steel, reduce production costs, reduce carbon emissions, and produce products with excellent performance, ensuring the long service life requirements of wear-resistant media. It can meet users' requirements for high purity, high fatigue life, and high wear resistance of wear-resistant media.

Description

Technical Field

[0001] This invention belongs to the fields of metallurgy and materials technology, specifically relating to a long-life wear-resistant steel S650A and its manufacturing method. Background Technology

[0002] Mining wear-resistant media, including steel grinding rods, grinding sections, and grinding balls, are consumables primarily used for grinding materials to achieve finer grinding and meet applicable standards. They are mainly used in mines, power plants, cement plants, steel mills, silica sand plants, and coal chemical industries. Globally, the annual consumption of steel for mining wear-resistant media is 30-50 million tons, with my country consuming approximately 3-5 million tons of steel balls annually, making it a major consumer of steel balls. In the context of global efforts to promote low-carbon emissions reduction, extending the service life of wear-resistant media can significantly reduce consumption and costs, contributing to energy conservation and emission reduction. Summary of the Invention

[0003] To meet the requirements of high purity, long fatigue life, and high wear resistance of wear-resistant media, this invention provides a long-life wear-resistant media steel S650A and its manufacturing method. It can effectively improve the service life of wear-resistant media steel, reduce production costs, reduce carbon emissions, and has excellent product performance, ensuring the long service life requirements of wear-resistant media and meeting the user's requirements.

[0004] A long-life wear-resistant steel S650A, wherein the chemical composition of the wear-resistant steel is as follows (mass content): C: 0.75%–0.85%, Si: 0.15%–0.40%, Mn: 1.00%–1.10%, P≤0.025%, S≤0.012%, Cr: 1.00%–1.10%, Mo: 0.06%–0.10%, Al: 0.015%–0.030%, Cu≤0.40%, Ni≤0.20%, Ti≤0.01%, V≤0.03%, Sn≤0.03%, O≤0.0015%, N: 0.0045%–0.0100%, H≤0.0001%, with the balance being iron and unavoidable impurities.

[0005] A method for manufacturing the aforementioned long-life wear-resistant steel S650A, the method comprising the following steps: smelting molten steel in an ECOARC ecological electric arc furnace, refining molten steel in an LF ladle refining furnace, refining molten steel in an RH vacuum circulation degassing furnace, continuous casting (390mm×480mm large square billet), heating in a walking beam heating furnace, and rolling on a 1150BD continuous rolling mill.

[0006] ①ECOARC Eco-friendly Electric Arc Furnace Smelting

[0007] Scrap steel is used as the steelmaking material, and the scrap steel is light and thin. The total amount of steelmaking material added is 125-135t / furnace. The steelmaking material is added in 10-12 batches. Graphite briquetting is used for carbon addition, and the carbon content is ≥1.50%. Oxygen blowing is added to the electrodes to assist melting. Automatic slag flow process is used for blowing. Activated lime and magnesite are used for slag formation and dephosphorization. The lime addition is 3000-5000kg / furnace, and the magnesite addition is 1000-2000kg / furnace. Carbon powder is continuously injected into the smelting process to create foamy slag.

[0008] The steel tapping requirements are C≥0.10%, P≤0.010%, and other residual elements must be qualified. The temperature is 1610℃~1630℃. When tapping 15~20t, add pre-deoxidizer (50~150kg / heat of aluminum wire), carbon raiser, ferroalloy (1600~1800kg / heat of high chromium, 600~800kg / heat of silicon manganese, 540~560kg / heat of high manganese), and slag (500~700kg / heat of active lime). The addition is completed when tapping 70t.

[0009] ②LF Refining

[0010] Diffusion deoxidation using silicon carbide and aluminum particles is employed, followed by white slag smelting with a white slag time ≥25 min. Argon stirring is performed throughout the refining process using bottom blowing from the ladle. The steel composition and temperature are precisely adjusted to target requirements during refining to ensure no alloying is added after RH degassing, and the aluminum content in the steel is adjusted to a suitable range to avoid aluminum addition after RH degassing.

[0011] Furthermore, the composition of the steel produced by LF refining is controlled according to the values ​​in Table 1. The main chemical components of the molten steel from LF are controlled as follows: C: 0.78%–0.85%, Si: 0.24%–0.35%, Mn: 1.03%–1.10%, P≤0.025%, S≤0.012%, Cr: 1.03%–1.10%, Mo: 0.06%–0.10%, Al: 0.015%–0.030%, Cu≤0.20%, Ni≤0.15%, Ti≤0.01%, V≤0.03%, Sn≤0.03%, O≤0.0015%, N: 0.0050%–0.095%. Details are as follows:

[0012] Table 1. Main Chemical Composition of Molten Steel from LF

[0013]

[0014]

[0015] Furthermore, the control of the LF tapping temperature is shown in Table 2. The tapping temperature control parameters are 1609℃~1619℃ for the first heat, 1579℃~1589℃ for the second heat, and 1569℃~1579℃ for the third heat and thereafter.

[0016] Table 2 Process parameters for LF tapping temperature control

[0017]

[0018] ③RH Refining

[0019] The RH (Refrigerant Regulator) uses high vacuum for circulating degassing to ensure the hydrogen content is below 0.0001% before leaving the station. The RH inlet temperature is 1564℃~1614℃. Before entering the RH, the Al content of the molten steel must be adjusted to 0.015%~0.030% to ensure the finished product Al reaches 0.015%~0.025%. The vacuum level must reach below 100Pa within 2 minutes and be maintained for at least 30 minutes. After repressurization, the static argon blowing time is ≥25 minutes, ensuring slight slag surface movement and no exposed molten steel, to prevent secondary oxidation. The ladle temperature is controlled between 1519℃~1559℃; in principle, the RH composition should not be adjusted, but if adjustment is necessary, ensure a net circulation time of more than 8 minutes. The RH refining temperature control is shown in Table 3. The RH refining ladle temperature control parameters are: 1549℃~1559℃ for the first heat, 1529℃~1539℃ for the second heat, and 1519℃~1529℃ for the third heat and subsequent heats.

[0020] Table 3 Temperature control parameters for RH refining

[0021]

[0022] The chemical composition of the molten steel produced by RH refining is controlled as shown in Table 4. The main chemical components of the molten steel produced by RH refining are controlled as follows: C: 0.78%–0.85%, Si: 0.24%–0.35%, Mn: 1.03%–1.10%, P≤0.025%, S≤0.012%, Cr: 1.03%–1.10%, Mo: 0.06%–0.10%, Al: 0.015%–0.030%, Cu≤0.20%, Ni≤0.15%, Ti≤0.01%, V≤0.03%, Sn≤0.03%, H≤0.0002%, O≤0.0015%, N: 0.0050%–0.095%, H≤0.0001%.

[0023] Table 4. Mass content of main chemical components in molten steel from RH refining.

[0024]

[0025] ④ Continuous casting

[0026] To prevent hydrogen accumulation in the ladle, the tundish baking time should be greater than 240 min, and the baking temperature ≥1000℃ to ensure proper baking. Before continuous casting begins, confirm the ladle cover is sealed, fill the tundish with argon, and pour at full liquid level; for the ladle long nozzle protection, pour argon at a rate of 20–40 NL / min, ensuring the tundish liquid level fluctuates slightly without exposing the molten steel surface; maintain a constant casting speed, and do not allow adjustment of the casting speed; automatically add protective slag; control liquid level fluctuations by eddy current detection: ±3 mm; employ electromagnetic stirring in the crystallizer, end electromagnetic stirring, and heavy pressure processes to improve core density. Specific continuous casting process parameters are shown in Tables 5 and 6.

[0027] Table 5 Temperature control parameters for continuous casting process (unit: °C)

[0028]

[0029] Table 6 Control parameters for continuous casting process

[0030]

[0031]

[0032] ⑤ Heating and rolling

[0033] Heating is carried out using a regenerative walking beam furnace. The billet shape is 390mm×480mm, the high-temperature diffusion temperature is 1200℃~1250℃, the high-temperature diffusion time is ≥5.5h, the total heating time is ≥10h, and the furnace exit temperature is 1190℃~1210℃.

[0034] Rolling is performed using a 1150BD roughing mill, followed by rolling with 800 and 650 finishing mills, producing specifications ranging from Ф35 to Ф100mm. Small bars are rolled using a 24-stand Danieli finishing mill, equipped with a sizing mill. Rolled steel should be slowly cooled promptly. Steel ≥Φ85mm requires heat preservation treatment: initial temperature ≥550℃, exit temperature ≤200℃, and holding time ≥48 hours. Steel <Φ85mm undergoes a timely stacking cooling process.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This invention provides a long-life wear-resistant media steel S650A and its manufacturing method. The wear-resistant media S650A is produced by "ECOARC ecological electric furnace smelting + LF furnace refining + RH vacuum treatment + continuous casting + 1150BD continuous rolling mill". It can effectively improve the service life of wear-resistant media steel, reduce production costs, reduce carbon emissions, and the product has excellent performance, ensuring the long service life requirements of wear-resistant media. It can meet users' requirements for high purity, high fatigue life, and high wear resistance of wear-resistant media. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments, but this does not limit the invention in any way. To avoid redundancy, unless otherwise specified, the raw materials used in the following embodiments are all commercially available products, and the methods used are all conventional methods unless otherwise specified.

[0038] A long-life wear-resistant steel S650A and its manufacturing method are disclosed. The chemical composition of the wear-resistant steel is as follows (mass content): C: 0.75%–0.85%, Si: 0.15%–0.40%, Mn: 1.00%–1.10%, P≤0.025%, S≤0.012%, Cr: 1.00%–1.10%, Mo: 0.06%–0.10%, Al: 0.015%–0.030%, Cu≤0.40%, Ni≤0.20%, Ti≤0.01%, V≤0.03%, Sn≤0.03%, O≤0.0015%, N: 0.0045%–0.0100%, H≤0.0001%, with the balance being iron and unavoidable impurities.

[0039] A method for manufacturing the above-mentioned long-life wear-resistant media steel S650A, the method comprising the following steps: ecological electric arc furnace smelting, LF refining, RH refining, continuous casting, and heated rolling;

[0040] ① Ecological electric arc furnace smelting: Scrap steel is used as the steel material, with a total addition of 125-135t / furnace; graphite briquettes are used for carbon addition, with a carbon content of ≥1.50%; the tapped steel has C ≥0.10% and P ≤0.010%, and the temperature is 1610℃~1630℃;

[0041] ②LF refining: Silicon carbide + aluminum particles are used for diffusion deoxidation, white slag smelting, and the white slag time is ≥25min; the whole refining process is carried out by bottom blowing argon stirring in the ladle, and the steel composition and temperature are finely adjusted to the target requirements during the refining process;

[0042] ③RH refining: High vacuum circulation degassing is adopted, and the hydrogen content is reduced to below 0.0001% before leaving the station; the RH entry temperature is 1564℃~1614℃, and the Al content of the molten steel is adjusted to 0.015%~0.030% before entering the RH.

[0043] ④ Continuous casting: Tundish baking time greater than 240 min, baking temperature ≥1000℃; first heat turntable temperature 1544℃~1554℃, tundish temperature 1484℃~1494℃, superheat 30℃~40℃; second heat turntable temperature 1534℃~1544℃, tundish temperature 1474℃~1484℃, superheat 20℃~35℃; third to last heat turntable temperature 1524℃~1534℃, tundish temperature 1474℃~1484℃, superheat 20℃~35℃;

[0044] ⑤ Heating and rolling: Heating is carried out in a regenerative walking beam furnace with a high-temperature diffusion temperature of 1200℃~1250℃, a high-temperature diffusion time of ≥5.5h, a total heating time of ≥10h, and a furnace exit temperature of 1190℃~1210℃.

[0045] After rolling, the steel is slowly cooled. The temperature of the large steel bars entering the pit is ≥550℃, the temperature of the bars exiting the pit is ≤200℃, and the heat preservation time is ≥48h; the small steel bars are cooled in a pile.

[0046] Any aspects not described in the following embodiments are the same as those described in the specific embodiments above.

[0047] Example

[0048] A long-life wear-resistant steel S650A and its manufacturing method are described below.

[0049] ①ECOARC Eco-friendly Electric Arc Furnace Smelting

[0050] Scrap steel was used as the steel material, with a total addition of 129 tons. Graphite briquetting was used for carbon addition, with a carbon content of 1.60%. Oxygen blowing was added to the electrodes for smelting, and an automatic slag flow process was used for blowing. Activated lime and magnesite were used for slag formation and dephosphorization, with 3800 kg of lime and 1600 kg of magnesite added. Carbon powder was continuously injected during the smelting process to create foamed slag, consuming 1200 kg of foaming agent.

[0051] The steel tapping requirements are C 0.15%, P 0.008%, and other residual elements must be within acceptable limits. The temperature is 1618℃. When the steel tapping reaches 15t, add pre-deoxidizer (80kg aluminum wire segments), 600kg carbon raiser, ferroalloy (1700kg / heat of high chromium, 700kg / heat of silicon manganese, and 550kg / heat of high manganese), and slag (600kg / heat of active lime). The addition is completed when the steel tapping reaches 70t.

[0052] ②LF Refining

[0053] Diffusion deoxidation using silicon carbide and aluminum granules was employed, followed by white slag smelting with a white slag time of 27 minutes. Argon stirring was used throughout the refining process, with bottom blowing from the ladle. The steel composition and temperature were fine-tuned to target requirements during refining to ensure no alloying was added after RH degassing, and the aluminum content in the steel was adjusted to 0.028% to avoid aluminum addition after RH degassing. The LF discharge temperature was 1615℃. The LF tapping steel composition is as follows:

[0054] The main chemical composition of the molten steel produced by LF refining is controlled as follows: C: 0.81%, Si: 0.28%, Mn: 1.07%, P: 0.016%, S: 0.003%, Cr: 1.06%, Mo: 0.08%, Al: 0.025%, Cu: 0.05%, Ni: 0.06%, Ti: 0.0055%, V: 0.01%, Sn: 0.002%, H: 0.00016%, O: 0.0005%, N: 0.065%.

[0055] ③RH Refining

[0056] The RH system employs high vacuum for circulating degassing to ensure that the hydrogen content is below 0.0001% before leaving the station. The RH inlet temperature is 1610℃, and the Al content before entering the RH system is 0.025%. The vacuum level is lower than 68 Pa within 2 minutes and maintained for 32 minutes. After repressurization, the static argon blowing time is 27 minutes, and the hoisting temperature is 1556℃.

[0057] The main chemical composition of the molten steel refined by RH is controlled as follows: C: 0.805%, Si: 0.27%, Mn: 1.06%, P: 0.016%, S: 0.003%, Cr: 1.05%, Mo: 0.08%, Al: 0.022%, Cu: 0.05%, Ni: 0.06%, Ti: 0.0058%, V: 0.01%, Sn: 0.002%, H: 0.00008%, O: 0.0004%, N: 0.065%.

[0058] ④ Continuous casting

[0059] The tundish baking time is 265 minutes, and the baking temperature is 1100℃ to ensure proper baking. Before continuous casting begins, confirm the ladle cover is sealed, purge the tundish with argon for 10 minutes, and pour at full liquid level. For the ladle, use a long nozzle protection system with an argon flow rate of 26 NL / min, ensuring the tundish liquid level fluctuates slightly without exposing the molten steel. Maintain a constant casting speed; speed adjustments are not permitted. Automatic addition of protective slag is used. Eddy current detection controls liquid level fluctuations to ±3mm. Electromagnetic stirring in the crystallizer, end-point electromagnetic stirring, and heavy pressure are employed to improve core density. The turntable temperature is 1552℃, and the tundish temperatures are 1492℃, 1494℃, 1492℃, and 1489℃. Specific continuous casting process parameters are shown in Tables 7 and 8.

[0060] Table 7 Continuous casting process parameters for the embodiments

[0061]

[0062]

[0063] Table 8. Process parameters for continuous casting under heavy pressure in the embodiments.

[0064] Roller serial number 3 4 5 6 7 Indentation, mm 2 3 4 7 9

[0065] ⑤ Heating and rolling

[0066] Heating is performed using a regenerative walking beam furnace with a heating temperature of 1210℃, a soaking time of 350min, a total heating time of 640min, and an exit temperature of 1198℃.

[0067] The rolling process employed a 24-stand Danieli finishing mill to produce Ф100mm steel. After rolling, the steel was kept at a temperature of 650℃ upon entering the mill for 50 hours, and then exited at 150℃. The mill strokes are shown in Table 9.

[0068] Table 9. Rolling Parameters of the Finishing Mill in the Embodiments

[0069]

[0070] The chemical composition of the finished long-life wear-resistant media steel S650A prepared in the examples is shown in Table 10, the inclusion characteristics are shown in Table 11, and the low-magnification microstructure is shown in Table 12. The results show that the oxygen content of the steel reaches 3 ppm, and the total inclusion level is ≤3.0, indicating high purity. The general porosity and central porosity of the steel in low-magnification are both ≤0.5, and the ingot segregation and central segregation are both 0, indicating high density.

[0071] Table 10 Chemical composition of the finished wear-resistant media steel S650A prepared according to the examples

[0072]

[0073] Table 11. Inclusions in the finished products obtained from the examples.

[0074]

[0075] Table 12. Low-magnification microstructure of the finished products obtained in the examples.

[0076] Sample number Generally loose Central loose Ingot segregation Central segregation 1 0.5 0.5 0 0 2 0.5 0.5 0 0 3 0.5 0.5 0 0 4 0.5 0.5 0 0 5 0.5 0.5 0 0 6 0.5 0.5 0 0

[0077] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention, or equivalent embodiments can be modified based on the disclosed technical content, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A method of manufacturing a steel S650A for long-lasting abrasion-resistant media, characterized in that, The chemical composition of the wear-resistant medium steel is C: 0.81% to 0.85%, Si: 0.15% to 0.40%, Mn: 1.00% to 1.06%, P: 0.014% or less, S: 0.004% or less, Cr: 1.00% to 1.10%, Mo: 0.06% to 0.10%, Al: 0.015% to 0.030%, Cu: 0.05%, Ni: 0.07%, Ti: 0.01% or less, V: 0.01%, Sn: 0.002%, O: 0.0015% or less, N: 0.0045% to 0.0100%, and H: 0.0001% or less, with the balance being iron and inevitable impurities. The manufacturing method of the long-life wear-resistant medium steel S650A comprises the following steps: ecological electric arc furnace smelting, LF refining, RH refining, continuous casting, and heating rolling. ① Ecological electric arc furnace smelting: scrap steel is used as the steel material, the total addition amount is 125 to 135 t / furnace; graphite pressure ball is used for carbon addition, and the carbon addition amount is greater than or equal to 1.50%; the tapping C is greater than or equal to 0.10%, the P is less than or equal to 0.010%, and the temperature is 1610 to 1630 ℃. In the ecological electric arc furnace smelting process, active lime and magnesite are used for slagging and dephosphorization, the lime addition amount is 3000 to 5000 kg / furnace, and the magnesite is 1000 to 2000 kg / furnace; when 15 to 20 t of molten steel is tapped, a pre-deoxidizer, a carbon additive, an iron alloy, and a slag material are added, and the addition is completed when 70 t of molten steel is tapped; the pre-deoxidizer addition amount is 50 to 150 kg / furnace of aluminum wire segment, the iron alloy addition amounts are 1600 to 1800 kg / furnace of high-chromium, 600 to 800 kg / furnace of silicon manganese, and 540 to 560 kg / furnace of high manganese, and the slag material addition amount is 500 to 700 kg / furnace of active lime; ② LF refining: silicon carbide + aluminum particles are used for diffusion deoxidization, and white slag smelting is used, and the white slag time is greater than or equal to 25 min; argon stirring is used for the whole refining process, and the molten steel composition and temperature are precisely adjusted to the target requirements during the refining process; The main chemical composition of the molten steel tapped in the LF refining is controlled to be C: 0.81% to 0.85%, Si: 0.15% to 0.40%, Mn: 1.00% to 1.06%, P: 0.014% or less, S: 0.004% or less, Cr: 1.00% to 1.10%, Mo: 0.06% to 0.10%, Al: 0.015% to 0.030%, Cu: 0.05%, Ni: 0.07%, Ti: 0.01% or less, V: 0.01%, Sn: 0.002%, O: 0.0015% or less, and N: 0.0045% to 0.0100%; The tapping temperature control parameters of the LF refining are 1609 to 1619 ℃ for the first furnace, 1579 to 1589 ℃ for the second furnace, and 1569 to 1579 ℃ for the third furnace and later; ③ RH refining: high vacuum degree cycle degassing is used, and the hydrogen content is less than 0.0001% before leaving the station; the RH temperature is 1564 to 1609 ℃, and the Al content of the molten steel is adjusted to 0.015% to 0.030% before entering the RH; ​ ​ The RH refining process, vacuum degree 2 min to reach 100 Pa or less, and maintain 30 min or more; After re-pressing, static argon ≥ 25 min; The RH refining ladle temperature control parameters are 1549℃ ~ 1559℃ for the first furnace, 1529℃ ~ 1539℃ for the second furnace, and 1519℃ ~ 1529℃ for the third furnace and later; The main chemical composition of the RH refining molten steel is controlled as follows: C: 0.81% ~ 0.85%, Si: 0.15% ~ 0.40%, Mn: 1.00% ~ 1.06%, P≤0.014%, S≤0.004%, Cr: 1.00% ~ 1.10%, Mo: 0.06% ~ 0.10%, Al: 0.015% ~ 0.030%, Cu: 0.05%, Ni: 0.07%, Ti≤0.01%, V: 0.01%, Sn: 0.002%, O≤0.0015%, N: 0.0045% ~ 0.0100%, H≤0.0001%; ④ Continuous casting: the tundish baking time is greater than 240 min, and the baking temperature is ≥1000℃; The first furnace rotary table temperature is 1544℃ ~ 1554℃, the tundish temperature is 1484℃ ~ 1494℃, and the superheat is 30℃ ~ 40℃; The second furnace rotary table temperature is 1534℃ ~ 1544℃, the tundish temperature is 1474℃ ~ 1484℃, and the superheat is 20℃ ~ 35℃; The third furnace to the last furnace rotary table temperature is 1524℃ ~ 1534℃, the tundish temperature is 1474℃ ~ 1484℃, and the superheat is 20℃ ~ 35℃; ⑤ Heating rolling: using a heat accumulating type walking beam heating furnace for heating, high temperature diffusion temperature 1200℃ ~ 1250℃, high temperature diffusion time ≥5.5 h, total heating time ≥10 h, and the discharge temperature is 1190℃ ~ 1210℃; After rolling, the steel is slowly cooled, the large bar steel is treated with heat preservation into the pit temperature ≥550℃, and the out-pit temperature is ≤200℃, the heat preservation time is ≥48 h; The small bar is stack cooled. ​

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