Continuous casting method of HPB300 casting blank

Abstract

The invention discloses a continuous casting method of an HPB300 casting blank, and relates to the technical field of steel production. Comprising the steps that refined molten steel is introduced into a crystallizer for continuous casting and cooled through a secondary cooling area to form a casting blank, and the R angle of a copper pipe of the crystallizer is 9-11 mm. By increasing the R angle of the copper pipe of the crystallizer, the bending degree of the copper pipe of the crystallizer is reduced, the molten steel liquid level can be tightly attached to the inner wall face of the copper pipe to be solidified in the molten steel continuous casting process, and casting blank stripping is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and in particular to a continuous casting method of a HPB300 ingot. Background Art

[0002] In the process of steel smelting, continuous casting is the key process to transform liquid steel into solid steel billets. For some steel grades with low alloy content, such as HPB300, whose element composition includes C, Si, Mn, P, S and Fe, the heat transfer capacity of the billet is relatively poor during the continuous casting process, and it is easy to have defects such as billet de-squareness and even steel leakage, which seriously affects product quality control and safe production.

[0003] Taking HPB300 steel as an example, billet de-squareness means that one of the four corners of the cross section of the billet is less than 90° and the other is greater than 90°. The difference in diagonal length is generally used to indicate the amount of de-squareness. De-squareness of the billet is prone to induce cracks inside the billet, especially diagonal cracks, and the billet de-squareness will be accompanied by a certain degree of bulging, resulting in steel leakage accidents, affecting the normal production of the billet; the appearance of the billet after de-squareness is deformed, which is easy to loosen during the lifting process, causing damage to equipment or safety accidents, and on the other hand, it is difficult for the de-squared billet to absorb the hole during rolling, which is prone to folding defects, and it is difficult to push the steel in the heating furnace. Therefore, in order to avoid de-squareness and even steel leakage accidents in low-alloy steel, especially HPB300 steel, during the continuous casting process is one of the problems that need to be solved in this field.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a continuous casting method for HPB300 ingot.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides a continuous casting method for HPB300 ingots, comprising: introducing refined molten steel into a crystallizer for continuous casting and cooling in a secondary cooling zone to form ingots, wherein the R angle of the copper tube of the crystallizer is 9 to 11 mm.

[0008] The present invention has the following beneficial effects:

[0009] The invention provides a continuous casting method of HPB300 ingot, which reduces the bending degree of the copper tube of the crystallizer by increasing the R angle of the copper tube of the crystallizer, so that the molten steel liquid surface can be solidified close to the inner wall surface of the copper tube during the continuous casting of molten steel, thereby preventing the ingot from being out of square. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0011] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0012] In a first aspect, the present invention provides a continuous casting method for HPB300 ingots, comprising: introducing refined molten steel into a crystallizer for continuous casting and cooling in a secondary cooling zone to form ingots, wherein the R angle of the copper tube of the crystallizer is 9 to 11 mm.

[0013] Preferably, the R angle of the copper tube of the crystallizer is 10 mm. By increasing the R angle of the copper tube of the crystallizer, the curvature of the copper tube of the crystallizer is reduced, and the meniscus solidified shell is easier to stick to the inner wall of the copper tube under the static pressure of the molten steel, and the shell is less likely to produce cracks, so that during the continuous casting of molten steel, the molten steel liquid surface can solidify close to the inner wall of the copper tube to prevent the cast billet from de-squareness.

[0014] In an optional embodiment, when the mass percentage of S in the refined molten steel is greater than 0.025%, the continuous casting pulling speed is adjusted according to the mass percentages of Mn and S in the refined molten steel, including: when 30≥Mn / S>25, the continuous casting pulling speed is 2.3m / min; when 25≥Mn / S≥22, the continuous casting pulling speed is 2.1m / min; when Mn / S<22, the continuous casting pulling speed is 1.9m / min.

[0015] When the S content is too high, if a higher pulling speed is used for continuous casting, the square deviation phenomenon may be aggravated or even steel leakage may occur. Therefore, when the mass percentage of S in the refined steel water is greater than 0.025%, controlling the pulling speed within the above range according to the relationship between the S and Mn contents in the refined steel water is beneficial to reduce the steel leakage phenomenon.

[0016] When the S content is low, in order to improve the continuous casting efficiency, the continuous casting pulling speed can be adjusted according to the temperature of the molten steel. In an optional embodiment, when the mass percentage of S in the refined molten steel is less than or equal to 0.025%, the continuous casting pulling speed is adjusted according to the tundish temperature after the refined molten steel is transferred to the tundish and the superheat of the molten steel, including:

[0017] When the ladle temperature ≤1532℃ and / or the superheat of molten steel ≤20℃, the continuous casting pulling speed is 2.9m / min; when the ladle temperature satisfies 1532℃<tundish temperature≤1542℃ and / or the superheat of molten steel satisfies 20℃<molten steel superheat≤30℃, the continuous casting pulling speed is 2.7m / min; when the ladle temperature satisfies 1542℃<tundish temperature≤1557℃ and / or the superheat of molten steel satisfies 30℃<molten steel superheat≤45℃, the continuous casting pulling speed is 2.5m / min; when the ladle temperature is>1557℃ and / or the superheat of molten steel is>45℃, the continuous casting pulling speed is 2.0m / min.

[0018] By controlling the pulling speed within the above range, it is beneficial to ensure continuous casting efficiency while avoiding billet de-squareness. When the ladle temperature and molten steel superheat are both low, a higher pulling speed is used to ensure smooth continuous casting; when the ladle temperature and molten steel superheat are both high, a lower pulling speed is used to avoid high-temperature molten steel causing the solidified billet shell to become thinner and the billet shell strength to decrease, which in turn causes billet de-squareness. Mismatching of pulling speed and superheat will aggravate billet de-squareness and be accompanied by billet bulging.

[0019] In an optional embodiment, when the first heat of molten steel for starting continuous casting is processed by a LF furnace and the ladle used belongs to category A, B, or C, the temperature of the continuous casting platform is 1585-1599°C.

[0020] When the first batch of molten steel at the beginning of continuous casting is treated by the argon station, the temperature of the continuous casting platform is 1596-1610℃.

[0021] The temperature of the process platform is 1561~1571℃.

[0022] Preferably, during the continuous casting process, the temperature difference of the molten steel in the crystallizer is controlled to be less than or equal to 10° C., and the casting speed fluctuation range is ±0.3 m / min.

[0023] In an optional embodiment, when the mass percentage of S in the refined molten steel is greater than 0.015% and the superheat of the molten steel is greater than 45° C., the electromagnetic stirrer at the end of solidification is turned on to avoid de-squareness of the ingot.

[0024] The parameters of the electromagnetic stirrer at the end of solidification include: current 280-320A, frequency 7-9HZ, and pause of 1-5s every 15-20s of stirring.

[0025] For example, at the end of solidification, the electromagnetic stirrer stirs for 18 seconds, pauses for 3 seconds, then stirs for another 18 seconds, pauses for another 3 seconds, and repeats this cycle.

[0026] Since the ingot coming out of the crystallizer is only solidified on the surface and the inside is not completely solidified, it is necessary to cool the ingot by cooling water in the secondary cooling zone, i.e., secondary cooling water, to ensure that the molten steel inside the ingot is completely solidified.

[0027] In an optional embodiment, the secondary cooling water ratio in the secondary cooling zone is 0.9-0.98 L / kg. By reducing the secondary cooling water ratio, uniform cooling of the ingot is ensured and the ingot de-squareness phenomenon is avoided.

[0028] In an optional embodiment, the relationship between the secondary cooling water flow rate in the secondary cooling zone and the casting speed of the ingot includes:

[0029]

[0030] In an optional embodiment, the service life of the crystallizer is ≤ 600 furnaces. When the service life of the crystallizer increases, for example, it is replaced after 800 or even 1000 furnaces, which may cause the cooling of molten steel to remain in the copper tube, affect the inner cavity size of the copper tube, and reduce the adhesion between the molten steel and the inner wall of the crystallizer copper tube, resulting in the phenomenon of de-squareness of the ingot.

[0031] In an optional embodiment, the upper opening size of the copper tube of the crystallizer is (166-167) m×(164-165) m, the lower opening size is (165-166)×(163-164) mm, the copper tube height is 890-910 mm, the upper and lower opening difference is 1.4-1.6 mm, and the crystallizer taper is 2.0-2.3% / m.

[0032] Preferably, the upper opening size of the copper tube of the crystallizer is 166.6 mm×164.6 mm, the lower opening size is 165×163 mm, the copper tube height is 900 mm, the upper and lower opening difference is 1.6 mm, and the crystallizer taper is 2.1% / m.

[0033] The taper of the copper tube of the crystallizer is too small, and air gaps and uneven heat transfer are easily generated in the molten steel in the crystallizer, resulting in uneven thickness of the billet shell and de-squareness.

[0034] In an optional embodiment, the water inlet pressure of the cooling water main of the crystallizer is 1.0-1.3 MPa, and the flow rate is 890-920 m 3 / h; the single tube cooling water flow rate of the crystallizer is 150~160m 3 / h.

[0035] Preferably, the temperature difference between the inlet and outlet of the cooling water of the crystallizer is 7-8°C, and the water flow rate of the water seam of the crystallizer is 5-6m / s.

[0036] When the water cooling of the crystallizer is too weak, the heat flux density is too small, and the billet shell out of the lower mouth of the crystallizer will be too thin, causing steel leakage; when the water cooling of the crystallizer is too strong, the heat flux density is too large, which will cause uneven heat transfer and lead to de-squareness. Therefore, controlling the cooling water parameters of the crystallizer within the above range will help ensure the quality of the billet.

[0037] Example 1

[0038] The present embodiment provides a continuous casting method of HPB300 ingots, comprising the following steps: introducing refined molten steel into a crystallizer for continuous casting and cooling in a secondary cooling zone to form ingots.

[0039] Among them, the R angle of the copper tube of the crystallizer is 10mm, the upper opening size of the copper tube of the crystallizer is 166.6m×164.6m, the lower opening size is 165×163mm, the copper tube height is 900mm, the upper and lower opening difference is 1.6mm, and the crystallizer taper is 2.1% / m. The service life of the crystallizer is ≤600 furnaces.

[0040] In addition, the cooling water main inlet pressure of the crystallizer is controlled to be 1.1MPa and the flow rate is 895m 3 / h; the single tube cooling water flow rate of the crystallizer is 152m 3 / h, the temperature difference between the inlet and outlet of the cooling water in the crystallizer is 7.5℃, and the water flow rate of the water seam of the crystallizer is 5m / s.

[0041] Since the percentage of S in the refined molten steel is 0.0255%, the percentage of Mn in the molten steel is 0.716%, and Mn / S is 28, the continuous casting speed is 2.3min / m. The temperature of the platform during the continuous casting process is 1571℃, the temperature of the tundish process is 1558~1563℃, the temperature deviation of the tundish process is 5℃, and the temperature difference of the molten steel in the tundish during the continuous casting process is controlled to be less than or equal to 10℃, and the fluctuation range of the pulling speed is ±0.3m / min.

[0042] Since the mass percentage of S in the refined molten steel is greater than 0.015%, the tundish temperature is 1558°C, and the superheat of the molten steel is 48°C, which is greater than 45°C, the electromagnetic stirrer at the end of solidification is turned on to prevent the billet from de-squared. The parameters of the electromagnetic stirrer at the end of solidification include: current 300A, frequency 8HZ, stirring for 18s, pausing for 3s, then stirring for another 18s, pausing for another 3s, and so on.

[0043] Since the pulling speed of this embodiment is 2.3min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 9.0m 3 / h, flow rate in zone 1 is 8.1m 3 / h, flow rate in zone 2 is 3.7m 3 / h, flow rate in zone 3 is 1.5m 3 / h, the total flow rate is 24.8m 3 / h, and the specific water volume is 0.91~0.93L / kg.

[0044] A total of 25 furnaces were produced by the continuous casting method of HPB300 ingots provided in this embodiment, and 0 furnace had de-squareness or steel leakage defects.

[0045] Example 2

[0046] This embodiment provides a continuous casting method for HPB300 ingot, which is similar to Embodiment 1, except that:

[0047] Since the S content in the refined molten steel is 0.028%, the Mn content in the molten steel is 0.680%, and Mn / S is 24, the continuous casting speed is 2.1.

[0048] Since the pulling speed of this embodiment is 2.1min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 8.2m 3 / h, flow rate in zone 1 is 7.2m 3 / h, flow rate in zone 2 is 3.4m 3 / h, flow rate in zone 3 is 1.3m 3 / h, the total flow rate is 22.3m 3 / h, and the specific water volume is 0.9~0.93L / kg.

[0049] A total of 20 furnaces were produced by the continuous casting method of HPB300 ingots provided in this embodiment, and 0 furnace had de-squareness or steel leakage defects.

[0050] Example 3

[0051] This embodiment provides a continuous casting method for HPB300 ingot, which is similar to Embodiment 1, except that:

[0052] Since the S content in the refined molten steel is 0.038%, the Mn content in the molten steel is 0.76%, and Mn / S is 20, the continuous casting speed is 1.9.

[0053] Since the pulling speed of this embodiment is 1.9 min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 8.2 m 3 / h, flow rate in zone 1 is 7.2m 3 / h, flow rate in zone 2 is 3.6m 3 / h, flow rate in zone 3 is 1.8m 3 / h, the total flow rate is 20.2m 3 / h, and the specific water volume is 0.9~0.91L / kg.

[0054] A total of 18 furnaces were produced using the continuous casting method for HPB300 ingots provided in this embodiment, and no furnace had de-squareness or steel leakage defects.

[0055] Example 4

[0056] The present embodiment provides a continuous casting method of HPB300 ingots, comprising the following steps: introducing refined molten steel into a crystallizer for continuous casting and cooling in a secondary cooling zone to form ingots.

[0057] Among them, the R angle of the copper tube of the crystallizer is 10mm, the upper opening size of the copper tube of the crystallizer is 166.6m×164.6m, the lower opening size is 165×163mm, the copper tube height is 900mm, the upper and lower opening difference is 1.6mm, and the crystallizer taper is 2.1% / m. The service life of the crystallizer is ≤600 furnaces.

[0058] In addition, the cooling water main inlet pressure of the crystallizer is controlled to be 1.2MPa and the flow rate is 910m 3 / h; the single tube cooling water flow rate of the crystallizer is 156m 3 / h, the temperature difference between the inlet and outlet water of the crystallizer's cooling water is 7.5℃, and the water flow rate at the water seam of the crystallizer is 5.6m / s.

[0059] Since the content percentage of S in the refined molten steel is 0.017%, which is less than 0.025%, and the temperature of the tundish after the refined molten steel reaches the tundish is 1538℃, and the superheat of the molten steel is 28℃. Therefore, the continuous casting speed is 2.7m / min. The temperature of the platform during the continuous casting process is 1568℃, and the temperature of the tundish process is 1531~1538℃. During the continuous casting process, the temperature difference of the molten steel in the tundish is controlled to be less than or equal to 10℃, and the pulling speed is stably controlled at 2.7m / min, and the pulling speed fluctuation range is ±0.3m / min.

[0060] Since the pulling speed of this embodiment is 2.7min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 10.8m 3 / h, flow rate in zone 1 is 10.5m 3 / h, flow rate in zone 2 is 5.8m 3 / h, flow rate in zone 3 is 3.0m 3 / h, the total flow rate is 30.1m 3 / h, and the specific water volume is 0.9~0.98L / kg.

[0061] A total of 280 furnaces were produced by the continuous casting method of HPB300 ingots provided in this embodiment, and 0 furnace had de-squareness or steel leakage defects.

[0062] Example 5

[0063] The present embodiment provides a continuous casting method of HPB300 ingots, comprising the following steps: introducing refined molten steel into a crystallizer for continuous casting and cooling in a secondary cooling zone to form ingots.

[0064] Among them, the R angle of the copper tube of the crystallizer is 10mm, the upper opening size of the copper tube of the crystallizer is 166.6m×164.6m, the lower opening size is 165×163mm, the copper tube height is 900mm, the upper and lower opening difference is 1.6mm, and the crystallizer taper is 2.1% / m. The service life of the crystallizer is ≤600 furnaces.

[0065] In addition, the cooling water main inlet pressure of the crystallizer is controlled to be 1.3MPa and the flow rate is 920m 3 / h; the single tube cooling water flow rate of the crystallizer is 160m 3 / h, the temperature difference between the inlet and outlet of the cooling water in the crystallizer is 8℃, and the water flow rate of the water seam of the crystallizer is 6m / s.

[0066] Since the content of S in the refined molten steel is 0.012%, which is less than 0.025%, and the temperature of the tundish after the refined molten steel is in the tundish is 1562℃, and the superheat of the molten steel is 52℃. Therefore, the continuous casting speed is 1.8min / m. The temperature of the platform during the continuous casting process is 1570℃, the temperature of the tundish process is 1558~1562℃, and the temperature difference of the molten steel in the crystallizer is controlled to be less than or equal to 10℃ during the continuous casting process, and the fluctuation range of the pulling speed is ±0.3m / min.

[0067] Since the pulling speed of this embodiment is 1.8min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 7.59m 3 / h, flow rate in zone 1 is 6.83m 3 / h, flow rate in zone 2 is 3.24m 3 / h, flow rate in zone 3 is 1.31m 3 / h, the total flow rate is 18.97m 3 / h, and the specific water volume is 0.9L / kg.

[0068] A total of 25 furnaces were produced by the continuous casting method of HPB300 ingots provided in this embodiment, and 0 furnace had de-squareness or steel leakage defects.

[0069] Example 6

[0070] This embodiment provides a continuous casting method for HPB300 ingot, which is similar to Embodiment 5, except that:

[0071] Since the content percentage of S in the refined molten steel is less than 0.025%, and the temperature of the tundish after the refined molten steel is in the tundish is 1560° C., the superheat of the molten steel is 50° C. Therefore, the continuous casting speed is 2.0 min / m.

[0072] Since the pulling speed of this embodiment is 2.0min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 8.38m 3 / h, flow rate in zone 1 is 7.46m 3 / h, flow rate in zone 2 is 3.62m 3 / h, flow rate in zone 3 is 1.59m 3 / h, the total flow rate is 21.05m 3 / h, and the specific water volume is 0.9L / kg.

[0073] A total of 46 furnaces were produced using the continuous casting method for HPB300 ingots provided in this embodiment, and no furnace had de-squareness or steel leakage defects.

[0074] Example 7

[0075] This embodiment provides a continuous casting method for HPB300 ingot, which is similar to Embodiment 5, except that:

[0076] Since the content percentage of S in the refined molten steel is less than 0.025%, and the temperature of the tundish after the refined molten steel is in the tundish is 1545° C., the superheat of the molten steel is 35° C. Therefore, the continuous casting speed is 2.5 min / m.

[0077] Since the pulling speed of this embodiment is 2.5min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 10.19m 3 / h, flow rate in zone 1 is 9.51m 3 / h, flow rate in zone 2 is 5.01m 3 / h, flow rate in zone 3 is 2.52m 3 / h, the total flow rate is 27.23m 3 / h, and the specific water volume is 0.93L / kg.

[0078] A total of 68 furnaces were produced using the continuous casting method for HPB300 ingots provided in this embodiment, and no furnace had de-squareness or steel leakage defects.

[0079] Example 8

[0080] This embodiment provides a continuous casting method for HPB300 ingot, which is similar to Embodiment 5, except that:

[0081] Since the content percentage of S in the refined molten steel is less than 0.025%, and the temperature of the tundish after the refined molten steel is in the tundish is 1536° C., the superheat of the molten steel is 26° C. Therefore, the continuous casting speed is 2.7 min / m.

[0082] Since the pulling speed of this embodiment is 2.7min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 10.84m 3 / h, flow rate in zone 1 is 10.52m 3 / h, flow rate in zone 2 is 5.75m 3 / h, flow rate in zone 3 is 2.98m 3 / h, the total flow rate is 30.09m 3 / h, specific water volume is 0.95L / kg.

[0083] A total of 89 furnaces were produced using the continuous casting method for HPB300 ingots provided in this embodiment, and no furnace had de-squareness or steel leakage defects.

[0084] Example 9

[0085] This embodiment provides a continuous casting method for HPB300 ingot, which is similar to Embodiment 5, except that:

[0086] Since the content percentage of S in the refined molten steel is less than 0.025%, and the temperature of the tundish after the refined molten steel is in the tundish is 1528° C., the superheat of the molten steel is 18° C. Therefore, the continuous casting speed is 2.9 min / m.

[0087] Since the pulling speed of this embodiment is 2.9min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 11.46m 3 / h, flow rate in zone 1 is 11.63m 3 / h, flow rate in zone 2 is 6.58m 3 / h, flow rate in zone 3 is 3.49m 3 / h, the total flow rate is 33.17m 3 / h, and the specific water volume is 0.98L / kg.

[0088] A total of 186 furnaces were produced using the continuous casting method for HPB300 ingots provided in this embodiment, and no furnace had de-squareness or steel leakage defects.

[0089] Comparative Example 1

[0090] This comparative example provides a continuous casting method for HPB300 ingots, comprising the following steps: introducing refined molten steel into a crystallizer for continuous casting and cooling in a secondary cooling zone to form ingots.

[0091] Among them, the R angle of the copper tube of the crystallizer is 5mm, the upper opening size of the copper tube of the crystallizer is 167m×167m, the lower opening size is 164×164mm, the copper tube height is 900mm, the upper and lower opening difference is 3mm, and the crystallizer taper is 2.6% / m. The service life of the crystallizer is ≤1050 furnaces.

[0092] In addition, the cooling water main inlet pressure of the crystallizer is controlled to be 0.81MPa and the flow rate is 851m 3 / h; the single tube cooling water flow rate of the crystallizer is 137m 3 / h, the temperature difference between the inlet and outlet of the cooling water in the crystallizer is 9.6℃, and the water flow rate of the water seam of the crystallizer is 7.9m / s.

[0093] The temperature of the continuous casting platform is 1590±7℃, and the temperature of the process platform is 1582±5℃.

[0094] The temperature of the tundish after the refined molten steel reaches the tundish is 1568°C, and the superheat of the molten steel is 58°C. Therefore, the pulling speed is 1.8min / m.

[0095] Since the pulling speed of this comparative example is 1.8min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 10.88m 3 / h, flow rate in zone 1 is 9.78m 3 / h, flow rate in zone 2 is 4.63m 3 / h, flow rate in zone 3 is 1.91m 3 / h, the total flow rate is 27.19m 3 / h, and the specific water volume is 1.29L / kg.

[0096] A total of 68 furnaces were produced using the continuous casting method for HPB300 ingots provided in this comparative example, and 11 furnaces had de-squareness or steel leakage defects.

[0097] Comparative Example 2

[0098] This comparative example provides a continuous casting method for HPB300 ingot, the steps of which are similar to those of comparative example 1, except that:

[0099] The temperature of the tundish after the refined molten steel reaches the tundish is 1562°C, and the superheat of the molten steel is 52°C. Therefore, the pulling speed is 2.0 min / m.

[0100] Since the pulling speed of this comparative example is 2.0min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 12.92m 3 / h, flow rate in zone 1 is 11.61m 3 / h, flow rate in zone 2 is 5.74m 3 / h, flow rate in zone 3 is 2.67m 3 / h, the total flow rate is 32.94m 3 / h, and the specific water volume is 1.34L / kg.

[0101] A total of 82 furnaces were produced using the continuous casting method for HPB300 ingots provided in this comparative example, and 16 furnaces had de-squareness or steel leakage defects.

[0102] Comparative Example 3

[0103] This comparative example provides a continuous casting method for HPB300 ingot, the steps of which are similar to those of comparative example 1, except that:

[0104] The temperature of the tundish after the refined molten steel reaches the tundish is 1558°C, and the superheat of the molten steel is 48°C. Therefore, the pulling speed is 2.2min / m.

[0105] Since the pulling speed of this comparative example is 2.2min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 13.54m 3 / h, flow rate in zone 1 is 12.24m 3 / h, flow rate in zone 2 is 6.13m 3 / h, flow rate in zone 3 is 2.94m3 / h, the total flow rate is 34.85m 3 / h, and the specific water volume is 1.36L / kg.

[0106] A total of 75 furnaces were produced by the continuous casting method of HPB300 ingots provided in this comparative example, and 16 furnaces had de-squareness or steel leakage defects.

[0107] Comparative Example 4

[0108] This comparative example provides a continuous casting method for HPB300 ingot, the steps of which are similar to those of comparative example 1, except that:

[0109] The temperature of the tundish after the refined molten steel reaches the tundish is 1538°C, and the superheat of the molten steel is 28°C. Therefore, the pulling speed is 2.6min / m.

[0110] Since the pulling speed of this comparative example is 2.6min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 15.75m 3 / h, flow rate in zone 1 is 14.85m 3 / h, flow rate in zone 2 is 7.87m 3 / h, flow rate in zone 3 is 4.05m 3 / h, the total flow rate is 45.52m 3 / h, specific water volume is 1.4L / kg.

[0111] A total of 102 furnaces were produced by the continuous casting method of HPB300 ingots provided in this comparative example, and 22 furnaces had de-squareness or steel leakage defects.

[0112] Comparative Example 5

[0113] This comparative example provides a continuous casting method for HPB300 ingot, the steps of which are similar to those of comparative example 1, except that:

[0114] The temperature of the tundish after the refined molten steel reaches the tundish is 1530℃, and the superheat of the molten steel is 20℃, so the pulling speed is 2.8min / m.

[0115] Since the pulling speed of this comparative example is 2.8min / m, the parameters of the secondary cooling water include: the flow rate of the foot roll area is 16.69m 3 / h, flow rate in zone 1 is 16.21m 3 / h, flow rate in zone 2 is 8.82m 3 / h, flow rate in zone 3 is 4.64m 3 / h, the total flow rate is 46.36m 3 / h, and the specific water volume is 1.42L / kg.

[0116] A total of 118 furnaces were produced using the continuous casting method for HPB300 ingots provided in this comparative example, and 36 furnaces had de-squareness or steel leakage defects.

[0117] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A continuous casting method for HPB300 ingot, characterized in that: The method comprises the steps of passing refined molten steel into a crystallizer for continuous casting and cooling the molten steel in a secondary cooling zone to form a casting billet, and the R angle of the copper tube of the crystallizer is 9-11 mm.

2. The method according to claim 1, characterized in that When the mass percentage of S in the refined molten steel is greater than 0.025%, the casting speed is adjusted according to the mass percentage of Mn and S in the refined molten steel, including: When 30≥Mn / S>25, the continuous casting pulling speed is 2.3m / min; when 25≥Mn / S≥22, the continuous casting pulling speed is 2.1m / min; when Mn / S<22, the continuous casting pulling speed is 1.9m / min.

3. The method according to claim 1, characterized in that When the mass percentage of S in the refined molten steel is less than or equal to 0.025%, the casting speed is adjusted according to the temperature of the tundish after the refined molten steel is transferred to the tundish and the superheat of the molten steel, including: When the tundish temperature ≤1532℃ and / or the superheat of molten steel ≤20℃, the continuous casting pulling speed is 2.9m / min; when the tundish temperature satisfies 1532℃<tundish temperature≤1542℃ and / or the superheat of molten steel satisfies 20℃<molten steel superheat≤30℃, the continuous casting pulling speed is 2.7m / min; when the tundish temperature satisfies 1542℃<tundish temperature≤1557℃ and / or the superheat of molten steel satisfies 30℃<molten steel superheat≤45℃, the continuous casting pulling speed is 2.5m / min; when the tundish temperature>1557℃ and / or the superheat of molten steel>45℃, the continuous casting pulling speed is 2.0m / min.

4. The method according to claim 3, characterized in that When the first batch of molten steel at the beginning of continuous casting is processed by the LF furnace and the ladle used belongs to the A, B, and C categories, the temperature of the continuous casting platform is 1585-1599℃; When the first batch of molten steel at the beginning of continuous casting is treated by the argon station, the temperature of the continuous casting platform is 1596~1610℃; The temperature of the process platform is 1561-1571°C; Preferably, during the continuous casting process, the temperature difference of the molten steel in the crystallizer is controlled to be less than or equal to 10° C., and the casting speed fluctuation range is ±0.3 m / min.

5. The method according to claim 1, characterized in that When the mass percentage of S in the refined molten steel is greater than 0.015% and the superheat of the molten steel is greater than 45° C., turning on the electromagnetic stirrer at the end of solidification; The parameters of the electromagnetic stirrer at the end of solidification include: current 280-320A, frequency 7-9HZ, and pause of 1-5s every 15-20s of stirring.

6. The method according to claim 1, characterized in that The secondary cooling water specific water volume in the secondary cooling zone is 0.9 to 0.98 L / kg.

7. The method according to claim 6, characterized in that The relationship between the secondary cooling water flow rate in the secondary cooling zone and the casting speed of the ingot includes:

8. The method according to claim 1, characterized in that The service life of the crystallizer is ≤600 furnaces.

9. The method according to claim 1, characterized in that: The upper opening size of the copper tube of the crystallizer is (166-167) m×(164-165) m, the lower opening size is (165-166)×(163-164) mm, the copper tube height is 890-910 mm, the upper and lower opening difference is 1.4-1.6 mm, and the crystallizer taper is 2.0-2.3% / m; Preferably, the upper opening size of the copper tube of the crystallizer is 166.6 mm×164.6 mm, the lower opening size is 165×163 mm, the copper tube height is 900 mm, the upper and lower opening difference is 1.6 mm, and the crystallizer taper is 2.1% / m.

10. The method according to claim 1, characterized in that The inlet pressure of the cooling water main of the crystallizer is 1.0-1.3 MPa, and the flow rate is 890-920 m 3 / h; the single tube cooling water flow rate of the crystallizer is 150~160m 3 / h; Preferably, the temperature difference between the cooling water inlet and outlet of the crystallizer is 7-8° C., and the water flow rate of the water seam of the crystallizer is 5-6 m / s.

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