Continuous casting dynamic soft reduction method

Abstract

The invention discloses a continuous casting dynamic soft reduction method, and belongs to the technical field of continuous casting in the metallurgical industry. According to the method, the pressure of the solidification tail end of the casting blank is guaranteed while dynamic soft reduction is input, and the pressure should reach 180 bar or above. For a fan-shaped section with an axial clearance and a clearance, the due effect of dynamic soft reduction cannot be fully exerted according to soft reduction of the set reduction amount, according to the method, the solidification tail end pressure of the casting blank is guaranteed during soft reduction, center segregation of the manufactured casting blank is obviously relieved, and the internal quality of the casting blank is obviously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of continuous casting in the metallurgical industry, and in particular relates to a continuous casting dynamic soft reduction method. Background Art

[0002] Chemical analysis was performed by taking samples from the surface to the center of the cross-section of the ingot at regular intervals. It was found that the C, Mn, S and other elements in the center were significantly higher than those in other parts. This phenomenon is called center segregation. Center segregation is caused by the flow of unsolidified molten steel during the solidification process of the ingot, especially at the end of solidification. When the center segregation is severe and accompanied by center porosity, serious internal quality defects will occur after the ingot is rolled. Therefore, measures must be taken to reduce the center segregation of the ingot.

[0003] At present, due to the improvement of wide plate casting technology, many wide plate casting machines have dynamic water distribution and dynamic light pressure reduction functions. The pressure reduction position and pressure reduction amount will be automatically adjusted with the changes in steel type, molten steel superheat, cooling intensity and even the surrounding environment, and the center segregation is greatly improved. However, due to the inherent characteristics of some manufacturers' equipment, there are axial clearances and clearances in the fan-shaped segment bearings. The axial clearances and clearances are as small as less than 1mm and as large as more than 3mm, or the fan-shaped segments are severely worn. If the pressure reduction amount and pressure reduction range are set according to the dynamic light pressure reduction, the center segregation of the ingot cannot be improved, and the dynamic light pressure reduction does not play its due effect.

[0004] Baosteel's wide and thick plate casting machine uses Danieli technology and has never had dynamic light reduction. In 2023, the equipment was upgraded and renovated, using MCC Jingcheng's dynamic light reduction, but the effect was not good after it was put into use, and the center segregation of the ingot was serious. The reason is that Danieli's fan-shaped segment bearings have axial clearance and clearance, resulting in the light reduction according to the set reduction amount. The dynamic light reduction cannot fully play its due role, resulting in no improvement in the center segregation of the ingot. Summary of the invention

[0005] The purpose of the present invention is to provide a continuous casting dynamic soft reduction method to significantly improve the center segregation of the casting billet when shaft clearance and play exist in the sector bearings of some manufacturers and the center segregation of the casting billet cannot be improved according to the set process parameters of dynamic soft reduction.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a continuous casting dynamic soft reduction method, which ensures the pressure at the end of solidification of the ingot while performing dynamic soft reduction, and the pressure should reach above 180 bar.

[0008] Further, it specifically includes:

[0009] After normal pouring, dynamic light pressure is put into use with a pulling speed of 0.9m / min. The system calculates the pressure positions of 11, 12, and 13. The end of the pressure is at sector 13. The designed total pressure reduction is 7mm, and the pressure reduction range is 0.2-0.88. At this time, the outlet pressure of sector 13 at the end of the pressure reduction is 125bar. At this time, the outlet of sector 13 is manually adjusted to increase the pressure by 1.5mm to reach more than 180bar.

[0010] Further, it specifically includes:

[0011] After normal pouring, dynamic light pressure is put into use with a pulling speed of 1.1m / min. The system calculates the pressure positions of 9, 10, and 11 sections. The end of the pressure is at sector 11. The designed total pressure reduction is 7mm, and the pressure reduction range is 0.2-0.88. At this time, the inlet pressure of sector 11 at the end of the pressure reduction is 138bar, and the outlet pressure is 142bar. At this time, manual adjustment is made to increase the pressure of the inlet of sector 11 by 1mm and the outlet by 1.5mm, so that the inlet and outlet pressures reach more than 180bar.

[0012] Further, it specifically includes:

[0013] After normal pouring, dynamic light pressure is put into use with a pulling speed of 1.0m / min. The system calculates the pressure positions of 8, 9, and 10. The end of the pressure is at sector 10. The designed total pressure reduction is 7mm, and the pressure reduction range is 0.2-0.88. At this time, the inlet pressure of sector 10 at the end of the pressure reduction is 159bar, and the outlet pressure is 145bar. At this time, the inlet pressure of sector 11 is manually adjusted to increase by 0.5mm and the outlet pressure by 1.0mm, so that the inlet and outlet pressures are both above 180bar.

[0014] Furthermore, it is suitable for producing wind power steel Q355NE with a section of 300×2200

[0015] Furthermore, it is suitable for producing wind power steel Q355NE with a section of 250×2000.

[0016] Furthermore, it is suitable for producing wear-resistant steel BGNM450 with a section of 250×1600.

[0017] Furthermore, when the terminal pressure is ensured by this method, the center segregation of the ingot is significantly improved.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are:

[0019] The beneficial effect of the present invention is that for fan-shaped segments with axial clearance and play, the light reduction according to the set reduction amount cannot fully exert the due effect of dynamic light reduction. According to the method of the present invention, the terminal pressure of the ingot solidification is guaranteed during light reduction, the central segregation of the ingot obtained is significantly reduced, and the internal quality of the ingot is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings.

[0021] Figure 1 This is the low-magnification effect of the ingot in Example 1 of the present invention.

[0022] Figure 2 This is the low-magnification effect of the ingot in Example 2 of the present invention.

[0023] Figure 3 This is the low-magnification effect of the ingot in Example 3 of the present invention.

[0024] Figure 4 This is a low-magnification effect of the casting in the comparative example of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the implementation case of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the implementation case.

[0026] Embodiment 1:

[0027] According to the invention described in the present invention, the wind power steel Q355NE with a cross section of 300×2200 is produced: after normal pouring, dynamic light pressing is put into operation, the pulling speed is 0.9m / min, the system calculates the pressing positions 11, 12, and 13, the pressing end is at the fan-shaped section 13, the total designed pressing amount is 7mm, the pressing interval is 0.2-0.88, at this time, the pressure at the outlet of the fan-shaped section 13 at the pressing end is 125bar, at this time, the pressure at the outlet of the section 13 is manually adjusted to increase by 1.5mm, so that the pressure reaches more than 180bar, and the ingot sample is taken for low-power detection, Figure 1 This is a low-magnification photograph of this embodiment.

[0028] Embodiment 2:

[0029] According to the invention described in the present invention, the wind power steel Q355NE with a cross section of 250×2000 is produced: after normal pouring, dynamic light pressing is put into use, the pulling speed is 1.1m / min, the system calculates the pressing positions 9, 10, and 11, the pressing end is in the fan-shaped section 11, the total designed pressing amount is 7mm, the pressing range is 0.2-0.88, at this time, the inlet pressure of the fan-shaped section 11 at the pressing end is 138bar, and the outlet pressure is 142bar. At this time, the inlet pressure of section 11 is manually adjusted to increase by 1mm and the outlet pressure is increased by 1.5mm, so that the inlet and outlet pressures are both above 180bar, and the ingot sample is taken for low-power detection. Figure 2 This is a low-magnification photograph of this embodiment.

[0030] Embodiment 3:

[0031] According to the invention described in the present invention, wear-resistant steel BGNM450 with a cross section of 250×1600 is produced: after normal pouring, dynamic light pressing is put into operation, the pulling speed is 1.0m / min, the system calculates the pressing positions of 8, 9, and 10, the pressing end is at the fan-shaped 10th section, the designed total pressing amount is 7mm, the pressing interval is 0.2-0.88, at this time, the inlet pressure of the fan-shaped 10th section at the pressing end is 159bar, and the outlet pressure is 145bar. At this time, the inlet pressure of the 11th section is manually adjusted to be 0.5mm more, and the outlet pressure is 1.0mm more, so that the inlet and outlet pressures are both above 180bar, and the ingot sample is taken for low-power detection. Figure 3 This is a low-magnification photograph of this embodiment.

[0032] Comparative Example:

[0033] Casting of wind power steel Q355NE with a section of 250×2000: After normal pouring, dynamic light pressure was put into use, with a pulling speed of 1.1m / min. The system calculated the pressure positions 9, 10, and 11, with a designed total pressure reduction of 7mm and a pressure reduction range of 0.2-0.88. At this time, the inlet pressure of the fan-shaped 11th section at the end of the pressure reduction was 145bar, and the outlet pressure was 137bar. The ingot sample was taken for low-power detection. Figure 4 This is a low-magnification photograph of this comparison ratio.

[0034] Table 1 is the low-magnification results of the examples and comparative examples of the present invention rated according to YB / T4003-1997.

[0035] Table 1

[0036] Example Low magnification results Example 1 C1.0 Example 2 C0.5 Example 3 C1.0 Comparative Example B1.0

[0037] It can be seen that for the fan-shaped segments with axial clearance and play, the center segregation of the ingot is still relatively serious only by performing dynamic light reduction according to the set reduction amount and reduction range. However, when the reduction end pressure is guaranteed according to the method of the present invention, the center segregation of the ingot is significantly improved.

[0038] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A continuous casting dynamic soft reduction method, characterized in that: While applying dynamic soft pressure, ensure the pressure at the end of solidification of the ingot, and the pressure should reach more than 180bar.

2. The continuous casting dynamic soft reduction method according to claim 1, characterized in that: Specifically include: After normal pouring, dynamic light pressure is put into use with a pulling speed of 0.9m / min. The system calculates the pressure positions of 11, 12, and 13. The end of the pressure is at sector 13. The designed total pressure reduction is 7mm, and the pressure reduction range is 0.2-0.

88. At this time, the outlet pressure of sector 13 at the end of the pressure reduction is 125bar. At this time, the outlet of sector 13 is manually adjusted to increase the pressure by 1.5mm to reach more than 180bar.

3. The continuous casting dynamic soft reduction method according to claim 1, characterized in that: Specifically include: After normal pouring, dynamic light pressure is put into use with a pulling speed of 1.1m / min. The system calculates the pressure positions of 9, 10, and 11 sections. The end of the pressure is at sector 11. The designed total pressure reduction is 7mm, and the pressure reduction range is 0.2-0.

88. At this time, the inlet pressure of sector 11 at the end of the pressure reduction is 138bar, and the outlet pressure is 142bar. At this time, manual adjustment is made to increase the pressure of the inlet of sector 11 by 1mm and the outlet by 1.5mm, so that the inlet and outlet pressures reach more than 180bar.

4. The continuous casting dynamic soft reduction method according to claim 1, characterized in that: Specifically include: After normal pouring, dynamic light pressure is put into use with a pulling speed of 1.0m / min. The system calculates the pressure positions of 8, 9, and 10. The end of the pressure is at sector 10. The designed total pressure reduction is 7mm, and the pressure reduction range is 0.2-0.

88. At this time, the inlet pressure of sector 10 at the end of the pressure reduction is 159bar, and the outlet pressure is 145bar. At this time, the inlet pressure of sector 11 is manually adjusted to increase by 0.5mm and the outlet pressure by 1.0mm, so that the inlet and outlet pressures are both above 180bar.

5. The continuous casting dynamic soft reduction method according to claim 2, characterized in that: Suitable for producing wind power steel Q355NE with a section of 300×2200.

6. The continuous casting dynamic soft reduction method according to claim 3, characterized in that: Suitable for producing wind power steel Q355NE with a section of 250×2000.

7. The continuous casting dynamic soft reduction method according to claim 4, characterized in that: Suitable for producing wear-resistant steel BGNM450 with a section of 250×1600.

8. The continuous casting dynamic soft reduction method according to any one of claims 1 to 7, characterized in that: According to this method, when the end pressure is pressed down, the center segregation of the ingot is significantly improved.

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