Continuous casting production method for gear steel

Abstract

The invention relates to the technical field of steel and iron smelting processes, in particular to a gear steel continuous casting production method which comprises the steps that firstly, the superheat degree of molten steel in a crystallizer is controlled to range from 15 DEG C to 25 DEG C; a four-side hole type submersed nozzle or a double-side hole type submersed nozzle is adopted in the continuous casting process of the round blank; a double-side hole type submersed nozzle is adopted in the continuous casting process of the rectangular blank and the square blank; 2, the throwing speed is controlled; 3, the cooling specific water flow of a secondary cooling area is controlled; fourthly, the rolling reduction of the continuous casting billet at the solidification tail end is controlled; electromagnetic stirring devices are arranged in the crystallizer, in a secondary cooling area and at the solidification tail end, the current intensity of the electromagnetic stirring devices is 0-1200 A, and the frequency of the electromagnetic stirring devices is 0-15 Hz. According to the method, the ingot segregation and CET interval segregation of the gear steel continuous casting billet are effectively controlled by regulating and controlling the technological parameters of the processes of crystallization, throwing, secondary cooling and solidification in the continuous casting production process of the gear steel, and the quality of the gear steel continuous casting billet is improved.

Description

Technical Field

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

[0002] With the continuous advancement of industrial technology, gear steel, as a key engineering material, plays a vital role in the fields of automobile, aerospace, machinery manufacturing, etc. 20CrMnTiH series round steel is a carburizing steel with good performance and high low-temperature impact toughness. It is mainly used to manufacture important parts with a cross-section of less than 30mm that withstand high-speed heavy loads, impact and friction, such as gears, gear rings, gear shafts, crossheads, etc. It is the most used steel in the gear industry. Heat treatment refers to heating, heat preservation and cooling of metal materials under a certain temperature, time and atmosphere, thereby changing the structure of metal materials and improving the performance of metal materials.

[0003] In order to improve the hardness, strength and toughness of gears and ensure the reliability and service life of gear transmission, it is usually necessary to heat treat the blank during the process of processing gears with 20CrMnTiH series round steel as blank. Due to the temperature difference between the inside and the surface of the round steel, there is a difference in the deformation of the inside and the surface of the round steel after heating. When there is different degrees of carbon segregation in the blank, the difference in the deformation between the inside and the surface of the round steel after heating will become larger, especially when the carbon segregation on the surface or shallow surface of the blank is large, the difference in the deformation between the inside and the surface of the round steel after heating will be more significant due to the larger deformation of the surface.

[0004] The use of arc continuous casting can alleviate the oxidation of the billet surface and reduce the inclusions in the billet, alleviate carbon segregation to a certain extent, and improve the quality of the billet. However, during the arc continuous casting process, due to the effect of gravity, the solidification process in the inner and outer arc directions may be consistent but the solidification structure evolution law may be inconsistent, resulting in asymmetric solute segregation positions in the CET interval and inducing deformation and fracture. Summary of the invention

[0005] In view of the technical problem that white bright bands and central cracks appear in continuous casting billets due to ingot segregation and CET interval segregation in the continuous casting billet, the present invention provides a gear steel continuous casting production method, which effectively controls the ingot segregation and CET interval segregation of the gear steel continuous casting billet by regulating the process parameters of crystallization, billet drawing, secondary cooling and solidification processes in the gear steel continuous casting production process, thereby improving the quality of the gear steel continuous casting billet.

[0006] The technical solution of the present invention is as follows: A gear steel continuous casting production method comprises the following steps: Step 1: Control the superheat of the molten steel in the crystallizer at 15-25°C; use a four-side hole type immersion nozzle or a double-side hole type immersion nozzle during the continuous casting of round billets; use a double-side hole type immersion nozzle during the continuous casting of rectangular billets and square billets; Step 2: Control the billet drawing speed. During the continuous casting process of the round billet, the billet drawing speed is controlled to 0.3-0.4 m / min. During the continuous casting process of the rectangular billet and the square billet, the billet drawing speed is controlled to 1.4-1.6 m / min. Step 3: Control the cooling water ratio in the secondary cooling zone. The cooling water ratio on the inner arc side of the continuous casting billet is 0.05-0.1 L / kg; the cooling water ratio on the outer arc side of the continuous casting billet is 0.2-0.35 L / kg; the cooling water ratio on the left and right sides of the continuous casting billet is 0.1-0.2 L / kg; Step 4: Control the reduction amount of the continuous casting billet at the end of solidification. The reduction amount on the left and right sides of the continuous casting billet is 2-5 mm, and the reduction amount on the outer and inner arc sides of the continuous casting billet is ≤ 2 mm. Electromagnetic stirring is set inside the crystallizer, in the secondary cooling zone and at the end of solidification. The current intensity of the electromagnetic stirring is 0-1200A, and the frequency of the electromagnetic stirring is 0-15Hz.

[0007] Furthermore, in step 1, a four-side hole type immersion nozzle is used for a round billet with a diameter of ≥500 mm; a double-side hole type immersion nozzle is used for a round billet with a diameter of <500 mm. The use of a side hole type immersion nozzle is beneficial to improving component segregation and reducing impurity accumulation. The present invention adjusts the number of side holes of the immersion nozzle according to the diameter of the round billet, which is beneficial to the uniform growth of the billet shell in the crystallizer and the stable flow of molten steel.

[0008] Furthermore, in step 1, the maximum fluctuation range of the liquid level of the molten steel is 0-2 mm, and the maximum thickness range of the shell of the molten steel is 0-30 mm.

[0009] Furthermore, in step 2, the cross-sectional length of the rectangular billet is 210-230 mm, the cross-sectional width of the rectangular billet is 170-190 mm, and the cross-sectional side length of the square billet is 210-230 mm. Rectangular billets and square billets have higher requirements for the flow distribution uniformity and temperature distribution uniformity of molten steel than circular billets, and the use of a double-side hole immersion nozzle can improve the flow distribution uniformity and temperature distribution uniformity of molten steel.

[0010] Furthermore, in step 3, the inner arc side of the continuous casting billet, the outer arc side of the continuous casting billet, the left side of the continuous casting billet and the right side of the continuous casting billet use independent cooling water. The cooling water used for the inner arc side of the continuous casting billet, the outer arc side of the continuous casting billet, the left side of the continuous casting billet and the right side of the continuous casting billet is controlled by the automatic control system according to the actual temperature of the continuous casting billet in the secondary cooling zone.

[0011] Furthermore, in step 4, a four-roller pressing system is used to control the pressing amount at the end of solidification.

[0012] Furthermore, the four-roller pressing system includes an upper roller, a lower roller, a left roller and a right roller, wherein the upper roller and the left roller are active rollers, and the lower roller and the right roller are driven rollers. The upper roller and the left roller are driven by a hydraulic motor, and the lower roller and the right roller are driven by the friction between them and the continuous casting billet.

[0013] Furthermore, during the continuous casting process of round billets with a diameter ≥500 mm, the current intensity of the electromagnetic stirring inside the crystallizer is 200-600 A, and the frequency is 1-10 Hz; the current intensity of the electromagnetic stirring in the secondary cooling zone is 100-400 A, and the frequency is 1-10 Hz; the current intensity of the electromagnetic stirring at the end of solidification is 400-1000 A, and the frequency is 1-15 Hz.

[0014] Furthermore, during the continuous casting process of rectangular billets, square billets or round billets with a diameter of less than 500 mm, the current intensity of the electromagnetic stirring inside the crystallizer is 100-600A, and the frequency is 1-10Hz; the current intensity of the electromagnetic stirring in the secondary cooling zone is 100-300A, and the frequency is 1-10Hz; the current intensity of the electromagnetic stirring at the end of solidification is 300-700A, and the frequency is 1-15Hz.

[0015] Furthermore, electromagnetic stirrers are used inside the crystallizer, in the secondary cooling zone, and at the end of solidification. Clockwise stirring, counterclockwise stirring, or alternating stirring can change the coil current direction of the electromagnetic stirrer, adjust the magnetic field direction in the molten steel, eliminate component segregation, regulate the viscosity of the molten steel, improve the microstructure uniformity of the molten steel during solidification, and reduce CET zone segregation.

[0016] The beneficial effects of the present invention are: The present invention provides a gear steel continuous casting production method, which controls the superheat of molten steel in the crystallization process, improves the equiaxed crystal rate, is beneficial to the homogenization of the continuous casting billet structure, selects an immersed water nozzle according to the cross-sectional shape of the billet, is beneficial to promote the uniform production of the billet shell in the crystallizer, and improves the flow stability of the molten steel; in the billet drawing process, the billet drawing speed is controlled according to the cross-sectional shape of the billet, the solidification process of the molten steel is controlled, the uniformity of the microstructure inside and on the surface of the continuous casting billet is improved, the CET zone segregation in the center of the continuous casting billet is reduced, and the quality of the continuous casting billet is improved; in the secondary cooling process, the internal A smaller cooling water ratio is applied to the arc side, a larger cooling water ratio is applied to the outer arc side of the continuous casting billet, and a medium cooling water ratio is applied to the left and right sides of the continuous casting billet to promote uniform growth of dendrites on all sides of the continuous casting billet; in the solidification process, a reduction of 2-5mm is applied to the left and right sides of the continuous casting billet, and a reduction of ≤2mm is applied to the outer and inner arc sides of the continuous casting billet to prevent excessive difference in deformation between the interior and surface of the continuous casting billet; electromagnetic stirring is set inside the crystallizer, in the secondary cooling zone and at the end of solidification, and the current intensity and frequency of the electromagnetic stirring are adjusted to improve the carbon segregation phenomenon of the continuous casting billet.

[0017] According to the characteristics of continuous casting billets with different cross-sectional shapes, the present invention reduces the superheat, matches the appropriate crystallizer submerged nozzle, adopts electromagnetic stirring and adjusts the pressure reduction at the end of solidification, controls the uniform growth of dendrites in all directions of the continuous casting billet, reduces ingot segregation defects, avoids the CET zone or the most serious segregation zone from appearing at the root or surface of the gear, thereby reducing the problem of gear deformation and fracture. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a low-magnification microstructure diagram of the gear steel continuous casting billet produced in Example 1. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0021] Example 1 A continuous casting production method for a rectangular gear steel continuous casting billet with a cross-sectional height of 180 mm and a cross-sectional width of 220 mm comprises the following steps: Step 1: Control the superheat of the molten steel in the crystallizer at 16°C; use a double-side hole immersion nozzle during the continuous casting process; control the maximum difference of the liquid level fluctuation of the molten steel to 1mm, and the maximum difference of the shell thickness of the molten steel to 15mm.

[0022] Step 2: Control the throwing speed and set the throwing speed to 1.45m / min.

[0023] Step 3: Control the cooling water ratio in the secondary cooling zone. The cooling water ratio on the inner arc side of the continuous casting billet is 0.1L / kg; the cooling water ratio on the outer arc side of the continuous casting billet is 0.2L / kg; the cooling water ratio on the left side of the continuous casting billet is 0.11L / kg, and the cooling water ratio on the right side of the continuous casting billet is 0.11L / kg. The inner arc side, the outer arc side, the left side and the right side of the continuous casting billet use independent cooling water. The cooling water used on the inner arc side, the outer arc side, the left side and the right side of the continuous casting billet is controlled by the automatic control system according to the actual temperature of the continuous casting billet in the secondary cooling zone.

[0024] Step 4: Control the amount of reduction of the continuous casting billet at the end of solidification. Use a four-roller reduction system to reduce the amount of reduction on the left and right sides of the continuous casting billet by 2.5 mm, and the reduction on the outer arc side and inner arc side of the continuous casting billet by 0.8 mm. The four-roller reduction system includes an upper roller, a lower roller, a left roller, and a right roller, wherein the upper roller and the left roller are active rollers, and the lower roller and the right roller are driven rollers. The upper roller and the left roller are driven by a hydraulic motor, and the lower roller and the right roller are driven by the friction between the continuous casting billet and the roller.

[0025] A rotary electromagnetic stirrer is installed inside the crystallizer and in the secondary cooling zone, and a composite electromagnetic stirrer is installed at the end of solidification. The current intensity of the rotary electromagnetic stirrer inside the crystallizer is 250A, the frequency is 1.5Hz, and clockwise, counterclockwise or alternating stirring is adopted; the current intensity of the rotary electromagnetic stirrer in the secondary cooling zone is 150A, the frequency is 3Hz, and clockwise, counterclockwise or alternating stirring is adopted; the current intensity of the composite electromagnetic stirrer at the end of solidification is 600A, the frequency is 5Hz, and clockwise, counterclockwise or alternating stirring is adopted.

[0026] Example 2 A continuous casting production method for a rectangular gear steel continuous casting billet with a cross-sectional height of 320 mm and a cross-sectional width of 420 mm comprises the following steps: Step 1: Control the superheat of the molten steel in the crystallizer at 17°C; use a double-side hole immersion nozzle during the continuous casting process; control the maximum difference of the liquid level fluctuation of the molten steel to 1.6mm, and the maximum difference of the shell thickness of the molten steel to 20mm.

[0027] Step 2: Control the throwing speed and set the throwing speed to 1.45m / min.

[0028] Step 3: Control the cooling water ratio in the secondary cooling zone. The cooling water ratio on the inner arc side of the continuous casting billet is 0.1L / kg; the cooling water ratio on the outer arc side of the continuous casting billet is 0.21L / kg; the cooling water ratio on the left side of the continuous casting billet is 0.11L / kg, and the cooling water ratio on the right side of the continuous casting billet is 0.11L / kg. Independent cooling water is used for the inner arc side, the outer arc side, the left side and the right side of the continuous casting billet. The cooling water used for the inner arc side, the outer arc side, the left side and the right side of the continuous casting billet is controlled by the automatic control system according to the actual temperature of the continuous casting billet in the secondary cooling zone.

[0029] Step 4: Control the amount of reduction of the continuous casting billet at the end of solidification. Use a four-roller reduction system to reduce the amount of reduction of the left and right sides of the continuous casting billet by 2.5 mm, and the reduction of the outer arc side and inner arc side of the continuous casting billet by 1.5 mm. The four-roller reduction system includes an upper roller, a lower roller, a left roller, and a right roller, wherein the upper roller and the left roller are active rollers, and the lower roller and the right roller are driven rollers. The upper roller and the left roller are driven by a hydraulic motor, and the lower roller and the right roller are driven by the friction between the continuous casting billet and the roller.

[0030] A rotary electromagnetic stirrer is installed inside the crystallizer and in the secondary cooling zone, and a composite electromagnetic stirrer is installed at the end of solidification. The current intensity of the rotary electromagnetic stirrer inside the crystallizer is 450A, the frequency is 1.5Hz, and clockwise, counterclockwise or alternating stirring is adopted; the current intensity of the rotary electromagnetic stirrer in the secondary cooling zone is 250A, the frequency is 3Hz, and clockwise, counterclockwise or alternating stirring is adopted; the current intensity of the composite electromagnetic stirrer at the end of solidification is 800A, the frequency is 5Hz, and clockwise, counterclockwise or alternating stirring is adopted.

[0031] Example 3 A continuous casting production method for a rectangular gear steel continuous casting billet with a cross-sectional height of 320 mm and a cross-sectional width of 420 mm comprises the following steps: Step 1: Control the superheat of the molten steel in the crystallizer at 18°C; use a double-side hole immersion nozzle during the continuous casting process; control the maximum value of the liquid level fluctuation of the molten steel to 1.6mm, and the maximum value of the shell thickness of the molten steel to 20mm.

[0032] Step 2: Control the throwing speed and set the throwing speed to 1.45m / min.

[0033] Step 3: Control the cooling water ratio in the secondary cooling zone. The cooling water ratio on the inner arc side of the continuous casting billet is 0.1L / kg; the cooling water ratio on the outer arc side of the continuous casting billet is 0.21L / kg; the cooling water ratio on the left side of the continuous casting billet is 0.11L / kg, and the cooling water ratio on the right side of the continuous casting billet is 0.11L / kg. Independent cooling water is used for the inner arc side, the outer arc side, the left side and the right side of the continuous casting billet. The cooling water used for the inner arc side, the outer arc side, the left side and the right side of the continuous casting billet is controlled by the automatic control system according to the actual temperature of the continuous casting billet in the secondary cooling zone.

[0034] Step 4: Control the amount of reduction of the continuous casting billet at the end of solidification. Use a four-roller reduction system to reduce the amount of reduction of the left and right sides of the continuous casting billet by 2.5 mm, and the reduction of the outer arc side and inner arc side of the continuous casting billet by 1.5 mm. The four-roller reduction system includes an upper roller, a lower roller, a left roller, and a right roller, wherein the upper roller and the left roller are active rollers, and the lower roller and the right roller are driven rollers. The upper roller and the left roller are driven by a hydraulic motor, and the lower roller and the right roller are driven by the friction between the continuous casting billet and the roller.

[0035] A rotary electromagnetic stirrer is installed inside the crystallizer and in the secondary cooling zone, and a composite electromagnetic stirrer is installed at the end of solidification. The current intensity of the rotary electromagnetic stirrer inside the crystallizer is 300A, the frequency is 1.5Hz, and clockwise, counterclockwise or alternating stirring is adopted; the current intensity of the rotary electromagnetic stirrer in the secondary cooling zone is 200A, the frequency is 3Hz, and clockwise, counterclockwise or alternating stirring is adopted; the current intensity of the composite electromagnetic stirrer at the end of solidification is 600A, the frequency is 7Hz, and clockwise, counterclockwise or alternating stirring is adopted.

[0036] Comparative Example 1 A continuous casting production method for a rectangular gear steel continuous casting billet with a cross-sectional height of 180 mm and a cross-sectional width of 220 mm comprises the following steps: Step 1: Control the superheat of the molten steel in the crystallizer at 18°C; use a double-side hole immersion nozzle during the continuous casting process; control the maximum difference of the liquid level fluctuation of the molten steel to 1mm, and the maximum difference of the shell thickness of the molten steel to 15mm.

[0037] Step 2: Control the throwing speed and set the throwing speed to 1.45m / min.

[0038] Step 3: Control the cooling water ratio in the secondary cooling zone. The cooling water ratio on the inner arc side of the continuous casting billet is 0.1L / kg; the cooling water ratio on the outer arc side of the continuous casting billet is 0.1L / kg; the cooling water ratio on the left side of the continuous casting billet is 0.1L / kg, and the cooling water ratio on the right side of the continuous casting billet is 0.1L / kg. Independent cooling water is used for the inner arc side, the outer arc side, the left side and the right side of the continuous casting billet. The cooling water used for the inner arc side, the outer arc side, the left side and the right side of the continuous casting billet is controlled by the automatic control system according to the actual temperature of the continuous casting billet in the secondary cooling zone.

[0039] Step 4: Control the amount of reduction of the continuous casting billet at the end of solidification. Use a four-roller reduction system to reduce the amount of reduction of the left and right sides of the continuous casting billet by 1.0 mm, and the reduction of the outer arc side and inner arc side of the continuous casting billet by 0.8 mm. The four-roller reduction system includes an upper roller, a lower roller, a left roller, and a right roller, wherein the upper roller and the left roller are active rollers, and the lower roller and the right roller are driven rollers. The upper roller and the left roller are driven by a hydraulic motor, and the lower roller and the right roller are driven by the friction between the continuous casting billet and the roller.

[0040] A rotary electromagnetic stirrer is installed inside the crystallizer and in the secondary cooling zone, and a composite electromagnetic stirrer is installed at the end of solidification. The current intensity of the rotary electromagnetic stirrer inside the crystallizer is 250A, the frequency is 1.5Hz, and clockwise, counterclockwise or alternating stirring is adopted; the current intensity of the rotary electromagnetic stirrer in the secondary cooling zone is 150A, the frequency is 3Hz, and clockwise, counterclockwise or alternating stirring is adopted; the current intensity of the composite electromagnetic stirrer at the end of solidification is 600A, the frequency is 5Hz, and clockwise, counterclockwise or alternating stirring is adopted.

[0041] The C uniformity, equiaxed crystal area ratio, white bright band and center crack of the gear steel continuous casting billets produced in Examples 1-3 and Comparative Example 1 were tested, and the test results are shown in Table 1.

[0042] Table 1 Test results of gear steel continuous casting billets produced in Examples 1-3 and Comparative Example 1

[0043] It can be seen from Table 1 that the continuous casting production method provided by the invention has a positive effect on reducing the width of the CET area and increasing the proportion of the equiaxed crystal area.

[0044] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A gear steel continuous casting production method, characterized in that: The steps include: Step 1: Control the superheat of the molten steel in the crystallizer at 15-25°C; use a four-side hole type immersion nozzle or a double-side hole type immersion nozzle during the continuous casting of round billets; use a double-side hole type immersion nozzle during the continuous casting of rectangular billets and square billets; Step 2: Control the billet drawing speed. During the continuous casting process of the round billet, the billet drawing speed is controlled to 0.3-0.4 m / min. During the continuous casting process of the rectangular billet and the square billet, the billet drawing speed is controlled to 1.4-1.6 m / min. Step 3: Control the cooling water ratio in the secondary cooling zone. The cooling water ratio on the inner arc side of the continuous casting billet is 0.05-0.1 L / kg; the cooling water ratio on the outer arc side of the continuous casting billet is 0.2-0.35 L / kg; the cooling water ratio on the left and right sides of the continuous casting billet is 0.1-0.2 L / kg; Step 4: Control the reduction amount of the continuous casting billet at the end of solidification. The reduction amount on the left and right sides of the continuous casting billet is 2-5 mm, and the reduction amount on the outer and inner arc sides of the continuous casting billet is ≤ 2 mm. Electromagnetic stirring is set inside the crystallizer, in the secondary cooling zone and at the end of solidification. The current intensity of the electromagnetic stirring is 0-1200A, and the frequency of the electromagnetic stirring is 0-15Hz.

2. A gear steel continuous casting production method as claimed in claim 1, characterized in that: In step 1, a four-side hole type immersion nozzle is used for a round billet with a diameter ≥500 mm; a double-side hole type immersion nozzle is used for a round billet with a diameter <500 mm.

3. A gear steel continuous casting production method as claimed in claim 2, characterized in that: In step 1, the maximum fluctuation range of the liquid level of the molten steel is 0-2 mm, and the maximum thickness range of the shell of the molten steel is 0-30 mm.

4. A gear steel continuous casting production method as claimed in claim 1, characterized in that: In step 2, the cross-sectional length of the rectangular billet is 210-230 mm, the cross-sectional width of the rectangular billet is 170-190 mm, and the cross-sectional side length of the square billet is 210-230 mm.

5. The gear steel continuous casting production method according to claim 1, characterized in that: In step three, independent cooling water is used for the inner arc side of the continuous casting billet, the outer arc side of the continuous casting billet, the left side of the continuous casting billet and the right side of the continuous casting billet respectively.

6. A gear steel continuous casting production method as claimed in claim 1, characterized in that: In step 4, a four-roller pressing system is used to control the pressing amount at the end of solidification.

7. A gear steel continuous casting production method as claimed in claim 6, characterized in that: The four-roller pressing system includes an upper roller, a lower roller, a left roller and a right roller, wherein the upper roller and the left roller are active rollers, and the lower roller and the right roller are driven rollers.

8. A gear steel continuous casting production method as claimed in claim 1, characterized in that: During the continuous casting process of round billets with a diameter of ≥500mm, the current intensity of the electromagnetic stirring inside the crystallizer is 200-600A, and the frequency is 1-10Hz; the current intensity of the electromagnetic stirring in the secondary cooling zone is 100-400A, and the frequency is 1-10Hz; the current intensity of the electromagnetic stirring at the end of solidification is 400-1000A, and the frequency is 1-15Hz.

9. A gear steel continuous casting production method as claimed in claim 1, characterized in that: During the continuous casting process of rectangular billets, square billets or round billets with a diameter of less than 500 mm, the current intensity of the electromagnetic stirring inside the crystallizer is 100-600A, and the frequency is 1-10Hz; the current intensity of the electromagnetic stirring in the secondary cooling zone is 100-300A, and the frequency is 1-10Hz; the current intensity of the electromagnetic stirring at the end of solidification is 300-700A, and the frequency is 1-15Hz.

10. A gear steel continuous casting production method as claimed in claim 1, characterized in that: Electromagnetic stirrers were used inside the crystallizer, in the secondary cooling zone and at the end of solidification.

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