Long-life wear-resistant medium steel S650A and manufacturing method thereof

Abstract

The invention discloses long-life wear-resistant medium steel S650A and a manufacturing method thereof, the wear-resistant medium steel comprises the following main chemical components in percentage by mass: 0.75%-0.85% of C, 0.15%-0.40% of Si, 1.00%-1.10% of Mn, 1.00%-1.10% of Cr, 0.06%-0.10% of Mo, 0.015%-0.030% of Al, 0.0045%-0.0100% of N. The wear-resistant medium S650A is produced by adopting ecological electric furnace smelting, LF furnace refining, RH vacuum treatment, continuous casting and a 1150BD continuous rolling unit; the service life of the steel for the wear-resistant medium can be effectively prolonged, the production cost is reduced, carbon emission is reduced, the product performance is excellent, the requirement for the long service life of the wear-resistant medium is met, and the use requirements of a user for high purity, long fatigue life, high wear resistance and the like of the wear-resistant medium can be met.

Description

Technical Field

[0001] The invention belongs to the field of metallurgy and material technology, and specifically relates to a long-life wear-resistant medium steel S650A and a manufacturing method thereof. Background Art

[0002] Wear-resistant steel for mining is divided into grinding rods, grinding segments and grinding balls, etc. It is a consumable product, and its main purpose is to grind materials to make them finer to meet the use standards; it is mainly used in mines, power plants, cement plants, steel plants, silica sand plants, coal chemical industry and other fields. The annual consumption of wear-resistant steel for mining in the world is 30 to 50 million tons, of which my country consumes about 3 to 5 million tons of steel balls annually, making it a major consumer of steel balls; in the context of the global promotion of low-carbon emission reduction, improving the service life of wear-resistant media can greatly reduce consumption, reduce costs, and contribute to energy conservation and emission reduction. Summary of the invention

[0003] In order to meet the requirements of high purity, high fatigue life, high wear resistance and the like of wear-resistant media, the present invention provides a long-life wear-resistant media steel S650A and a manufacturing method thereof, which can effectively improve the service life of the wear-resistant media steel, reduce production costs, and reduce carbon emissions. The product has excellent performance, ensures the longevity requirements of the wear-resistant media, and can meet the user's usage requirements.

[0004] A long-life wear-resistant medium steel S650A, the chemical composition mass content of the wear-resistant medium steel is 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%, and the balance is iron and unavoidable impurities.

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

[0006] ①ECOARC ecological electric arc furnace smelting

[0007] Scrap steel is used as steel material, and the scrap steel used is light and thin material. The total amount of steel material added is 125-135t / furnace, and the steel material is added in 10-12 batches. Graphite balls are used for C mixing, and the amount of C mixing is ≥1.50%. Oxygen blowing is added to the electrode to assist melting, and automatic slag flow process is used for blowing. Active lime and magnesite are used for slag making and dephosphorization. The amount of lime added is 3000-5000kg / furnace, and the amount of magnesite is 1000-2000kg / furnace. Carbon powder is continuously sprayed in the smelting process to make foamed slag.

[0008] The steel tapping requirements are C ≥ 0.10%, P ≤ 0.010%, other residual elements are qualified, and the temperature is 1610℃ ~ 1630℃; when 15-20t of steel is tapped, add pre-deoxidizer (aluminum wire segment 50-150kg / furnace), carburizer, ferroalloy (high chromium 1600-1800kg / furnace, silicon manganese 600-800kg / furnace, high manganese 540-560kg / furnace), slag (active lime 500-700kg / furnace), and add all the additions when 70t of steel is tapped.

[0009] ②LF refining

[0010] Silicon carbide + aluminum particles are used for diffusion deoxidation and white slag smelting, and the white slag time is ≥25min. Argon is blown and stirred at the bottom of the ladle during the whole refining process. During the refining process, the composition and temperature of the molten steel are finely adjusted to the target requirements to ensure that no alloy is added after RH degassing, and the aluminum in the steel is adjusted to the appropriate range to avoid aluminum addition after RH degassing.

[0011] Further, the composition of LF refining steel is controlled according to the values ​​in Table 1, and the mass content of the main chemical components of LF steel is controlled to be 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%. The details are as follows:

[0012] Table 1 Main chemical composition of molten steel from LF steelmaking

[0013]

[0014]

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

[0016] Table 2 LF tapping temperature control process parameters

[0017]

[0018] ③RH refining

[0019] RH uses high vacuum for cyclic degassing to ensure that the hydrogen content reaches less than 0.0001% before leaving the station. The temperature of entering RH is 1564℃~1614℃. Before entering RH, the Al content of molten steel should be adjusted to 0.015%~0.030%, so as to ensure that the Al content of the finished product reaches 0.015%~0.025%. The vacuum degree reaches below 100Pa within 2min and is maintained for more than 30min. After re-pressurization, the static argon blowing time is ≥25min, based on the slight movement of the slag surface and the molten steel is not exposed, to prevent secondary oxidation. The temperature of the hanging bag is controlled at 1519℃~1559℃; in principle, RH does not adjust the composition, and it is necessary to adjust to ensure that the net cycle is greater than 8min. The temperature control of RH refining is shown in Table 3. The temperature control parameters of RH refining hanging bag are 1549℃~1559℃ for the first furnace, 1529℃~1539℃ for the second furnace, and 1519℃~1529℃ for the third furnace and later.

[0020] Table 3 Temperature control parameters of RH refining

[0021]

[0022] The mass content of chemical components of molten steel produced by RH refining is controlled as shown in Table 4. The mass content of main chemical components of molten steel produced by RH refining is 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 Main chemical components of molten steel from RH refining

[0024]

[0025] ④Continuous casting

[0026] To prevent hydrogenation in the ladle, the baking time of the tundish is greater than 240 minutes, and the baking temperature is ≥1000℃ to ensure good baking. Before continuous casting, confirm that the ladle cover is sealed, the tundish is filled with argon, and the full liquid level is poured; the argon gas volume of the long water nozzle of the large ladle is 20-40NL / min, and the liquid level of the tundish moves slightly and the steel liquid surface is not exposed; maintain a constant pulling speed, and do not allow the pulling speed to be adjusted; automatically add protective slag: eddy current detection liquid level fluctuation control: ±3mm; use crystallizer electromagnetic stirring, end electromagnetic stirring and heavy pressure process to improve the density of the core. The specific process parameters of continuous casting are shown in Tables 5 and 6.

[0027] Table 5 Temperature control parameters of continuous casting process Unit: °C

[0028]

[0029] Table 6 Control parameters of continuous casting process

[0030]

[0031]

[0032] ⑤Heating rolling

[0033] It adopts regenerative walking beam heating furnace for heating, the blank 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 temperature is 1190℃~1210℃.

[0034] The rolling process uses 1150BD billet opening machine, 800 and 650 finishing mills for rolling, and the production specification range is Ф35~Ф100mm; small bars are rolled by 24 Danieli finishing mills, and equipped with sizing units; the steel should be slow-cooled in time after rolling. ≥Φ85mm steel insulation treatment, pit entry temperature ≥550℃, pit exit temperature ≤200℃, insulation time ≥48h; <Φ85mm steel timely collection of pile cooling process.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention provides a long-life wear-resistant medium steel S650A and a manufacturing method thereof. The wear-resistant medium S650A is produced by adopting "ECOARC ecological electric furnace smelting + LF furnace refining + RH vacuum treatment + continuous casting + 1150BD continuous rolling unit", which can effectively improve the service life of the wear-resistant medium steel, reduce production costs, and reduce carbon emissions. The product has excellent performance, ensures the longevity requirement of the wear-resistant medium, and can meet the user's requirements for high purity, high fatigue life, high wear resistance, etc. of the wear-resistant medium. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with specific examples, but the present invention is not limited in any way. To avoid redundant description, the raw materials in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0038] A long-life wear-resistant medium steel S650A and a manufacturing method thereof. The chemical composition mass content of the wear-resistant medium steel is 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%, and the balance is iron and unavoidable impurities.

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

[0040] ① Ecological arc furnace smelting: using scrap steel as steel material, the total addition amount is 125-135t / furnace; carbon content of graphite pellets is ≥1.50%; steel C ≥0.10%, P ≤0.010%, temperature 1610℃~1630℃;

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

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

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

[0044] ⑤ Heating rolling: heating by heat storage walking beam heating furnace, high temperature diffusion temperature 1200℃~1250℃, high temperature diffusion time ≥5.5h, total heating time ≥10h, furnace temperature 1190℃~1210℃;

[0045] After rolling, the steel is slowly cooled. For the insulation treatment of large bars, the temperature entering the pit is ≥550℃, the temperature leaving the pit is ≤200℃, and the insulation time is ≥48h; small bars are pile cooled.

[0046] The matters not described in the following embodiments are the same as the description of the above specific implementation methods.

[0047] Example

[0048] A long-life wear-resistant medium steel S650A and a manufacturing method thereof, the specific process flow is as follows:

[0049] ①ECOARC ecological electric arc furnace smelting

[0050] Scrap steel is used as steel material, with a total steel material addition of 129t. Graphite balls are used for C mixing, with a C content of 1.60%. Oxygen blowing is added to the electrode to assist melting, and automatic slag flow process is used for blowing. Active lime and magnesite are used for slag making and dephosphorization, with an addition of 3800kg of lime and 1600kg of magnesite. Carbon powder is continuously sprayed during the smelting process to make foamed slag, consuming 1200kg of foaming agent.

[0051] The steel tapping requirements are C 0.15%, P 0.008%, and other residual elements are qualified. The temperature is 1618℃. When 15t of steel is tapped, add pre-deoxidizer (80kg of aluminum wire segment), 600kg of carburizer, ferroalloy (1700kg of high chromium / furnace, 700kg of silicon manganese / furnace, 550kg of high manganese / furnace), and slag (600kg of active lime / furnace). All the addition is completed when 70t of steel is tapped.

[0052] ②LF refining

[0053] Silicon carbide + aluminum particles are used for diffusion deoxidation, white slag smelting, and the white slag time is 27 minutes. Argon is blown and stirred at the bottom of the ladle during the entire refining process. During the refining process, the composition and temperature of the molten steel are finely adjusted to the target requirements to ensure that no alloy is added after RH degassing, and the aluminum in the steel is adjusted to 0.028% to avoid aluminum addition after RH degassing. The LF leaving station temperature is 1615℃. The LF steel composition is as follows:

[0054] The main chemical components of the molten steel produced by LF refining are 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%, and N: 0.065%.

[0055] ③RH refining

[0056] RH uses high vacuum for cyclic degassing to ensure that the hydrogen content is below 0.0001% before leaving the station. The temperature entering RH is 1610℃, and the Al content before entering RH is 0.025%; the vacuum degree reaches below 68Pa within 2 minutes and is maintained for 32 minutes; the static argon blowing time after re-pressurization is 27 minutes, and the bag temperature is 1556℃.

[0057] The main chemical components of the molten steel produced by RH refining are 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%, and N: 0.065%.

[0058] ④Continuous casting

[0059] The baking time of the tundish is 265min, and the baking temperature is 1100℃ to ensure good baking. Before continuous casting, confirm that the cover is sealed, the tundish is filled with argon for 10min, and the full liquid level is poured; the argon gas volume of the long water nozzle of the large ladle is 26NL / min, and the liquid level of the tundish moves slightly and the steel liquid level is not exposed; maintain a constant pulling speed, and do not allow the pulling speed to be adjusted; automatically add protective slag: eddy current detection liquid level fluctuation control: ±3mm; use crystallizer electromagnetic stirring, end electromagnetic stirring and heavy pressure process to improve the density of the core. The turntable temperature is 1552℃, and the tundish temperature is 1492℃, 1494℃, 1492℃, and 1489℃. The specific continuous casting process parameters are shown in Tables 7 and 8.

[0060] Table 7 Continuous casting process parameters of the embodiment

[0061]

[0062]

[0063] Table 8 Process parameters of continuous casting under heavy pressure in Example

[0064] Roller No. 3 4 5 6 7 Depression, mm 2 3 4 7 9

[0065] ⑤Heating rolling

[0066] The heating is carried out in a regenerative walking beam heating furnace, with a heating temperature of 1210°C, a soaking time of 350 minutes, a total heating time of 640 minutes, and a furnace outlet temperature of 1198°C.

[0067] The rolling process is carried out by 24 Danieli finishing mills, and the rolling specification is 100mm steel. After rolling, the steel is kept warm, with the pit temperature of 650℃, the holding time of 50h, and the pit exit temperature of 150℃. The rolling process of the finishing mill is shown in Table 9.

[0068] Table 9 Rolling process parameters of the finishing mill group in the embodiment

[0069]

[0070] The finished chemical composition of the long-life wear-resistant medium steel S650A prepared in the embodiment is shown in Table 10, the finished inclusions are shown in Table 11, and the finished macrostructure is shown in Table 12. The results show that the oxygen content of the steel reaches 3ppm, the total inclusion level is ≤3.0, reflecting that the steel has a high purity, the general looseness and central looseness of the steel are both ≤0.5, and the ingot segregation and central segregation are both 0, reflecting that the steel has a high density.

[0071] Table 10 Chemical composition of the finished product of wear-resistant medium steel S650A prepared in Example

[0072]

[0073] Table 11: Inclusions in the finished product obtained in Example

[0074]

[0075] Table 12 Macrostructure of the finished product obtained in Example

[0076] Sample No. Generally loose Loose center Ingot segregation Center 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 any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A long-life wear-resistant medium steel S650A and a manufacturing method thereof, characterized in that: The chemical composition mass content of the steel for wear-resistant media is 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%, and the balance is iron and unavoidable impurities.

2. A method for manufacturing the long-life wear-resistant medium steel S650A as claimed in claim 1, characterized in that: The method comprises the following steps: ecological arc furnace smelting, LF refining, RH refining, continuous casting, and hot rolling; ① Ecological arc furnace smelting: using scrap steel as steel material, with a total addition of 125-135t / furnace; carbon addition in graphite pellets, with a carbon content of ≥1.50%; Steel tapping C ≥ 0.10%, P ≤ 0.010%, temperature 1610℃~1630℃; ②LF refining: silicon carbide + aluminum particles are used for diffusion deoxidation, white slag smelting, and the white slag time is ≥25min; argon blowing and stirring are carried out at the bottom of the ladle during the whole refining process, and the composition and temperature of the molten steel are finely adjusted to the target requirements during the refining process; ③RH refining: high vacuum cycle degassing is adopted, and the hydrogen content reaches below 0.0001% before leaving the station; the temperature entering RH is 1564℃~1614℃, and the Al content of molten steel is adjusted to 0.015%~0.030% before entering RH; ④Continuous casting: Tundish baking time is greater than 240min, baking temperature ≥1000℃; the first furnace turntable temperature is 1544℃~1554℃, the tundish temperature is 1484℃~1494℃, and the superheat is 30℃~40℃; the second furnace turntable temperature is 1534℃~1544℃, the tundish temperature is 1474℃~1484℃, and the superheat is 20℃~35℃; the third furnace to the last furnace turntable temperature is 1524℃~1534℃, the tundish temperature is 1474℃~1484℃, and the superheat is 20℃~35℃; ⑤ Heating rolling: heating by heat storage walking beam heating furnace, high temperature diffusion temperature 1200℃~1250℃, high temperature diffusion time ≥5.5h, total heating time ≥10h, furnace temperature 1190℃~1210℃; After rolling, the steel is slowly cooled. For the insulation treatment of large bars, the temperature entering the pit is ≥550℃, the temperature leaving the pit is ≤200℃, and the insulation time is ≥48h; small bars are pile cooled.

3. The manufacturing method according to claim 2, characterized in that: In the ecological arc furnace smelting process of step ①, active lime and magnesite are used for slagging and dephosphorization, and the amount of lime added is 3000-5000 kg / furnace, and the amount of magnesite added is 1000-2000 kg / furnace.

4. The manufacturing method according to claim 2, characterized in that: Step ① During the smelting process of the ecological electric arc furnace, when 15-20 tons of steel is tapped, a pre-deoxidizer, a carburizer, an ferroalloy, and slag are added, and the addition is completed when 70 tons of steel is tapped; The amount of the pre-deoxidizer added is 50-150 kg / furnace of aluminum segments, the amount of the ferroalloy added is 1600-1800 kg / furnace of high chromium, 600-800 kg / furnace of silicon manganese, and 540-560 kg / furnace of high manganese, and the amount of the slag added is 500-700 kg / furnace of active lime.

5. The manufacturing method according to claim 2, characterized in that: Step ② the main chemical components of the molten steel refined by LF are controlled by mass content 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%.

6. The manufacturing method according to claim 2, characterized in that: In step ②, the LF refining steel-making temperature control parameters are 1609°C to 1619°C for the first furnace, 1579°C to 1589°C for the second furnace, and 1569°C to 1579°C for the third furnace and thereafter.

7. The manufacturing method according to claim 2, characterized in that: In step ③, during the RH refining process, the vacuum degree reaches below 100 Pa within 2 minutes and is maintained for more than 30 minutes; after re-pressurization, argon is blown for ≥ 25 minutes; and the bag temperature is 1519°C to 1559°C.

8. The manufacturing method according to claim 2, characterized in that: Step ③ The RH refining bag temperature control parameters are 1549°C to 1559°C for the first furnace, 1529°C to 1539°C for the second furnace, and 1519°C to 1529°C for the third furnace and thereafter; The main chemical components of the molten steel produced by RH refining are controlled to be 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≤0.0001%, O≤0.0015%, and N: 0.0050%-0.095%.

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