CN110523942B - Control method for improving internal defects of high-carbon chromium bearing steel bloom - Google Patents
Control method for improving internal defects of high-carbon chromium bearing steel bloom Download PDFInfo
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- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
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- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
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- B22D11/18—Controlling or regulating processes or operations for pouring
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
Abstract
The invention discloses a control method for improving internal defects of a high-carbon chromium bearing steel bloom, which comprises the steps of casting molten steel into a large chamfer angle bloom with a liquid core, controlling continuous casting parameters and implementing a soft reduction process on the large chamfer angle bloom with the liquid core. The invention controls the included angle between the corner of the continuous casting blank and the wide surface of the casting blank to be 30-40 degrees, and the length of the bevel edge to be 45-60 mm; controlling the superheat degree of the molten steel in the tundish to be 15-30 ℃ and the drawing speed to be 0.70-0.85 m/min; and respectively implementing dynamic soft reduction and static soft reduction on the large-chamfer continuous casting billet with the liquid core. The invention solves the internal defects of high-carbon chromium bearing steel bloom such as pressing crack, center segregation and the like, and the high-carbon chromium bearing steel bloom is subjected to low-power inspection: the center porosity is 0-0.5 grade, the center segregation is 0.5-1.0 grade, the shrinkage cavity is 0-0.5 grade, the intermediate crack is 0-0.5 grade, the center crack is 0-0.5 grade, and the equiaxed crystal rate is 55-68 percent; the center carbon segregation index of the continuous casting slab is 0.95-1.06.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a control method for improving internal defects of a high-carbon chromium bearing steel bloom.
Background
With the development and progress of continuous casting technology and the improvement of the requirements on product quality, the section size of a casting blank tends to be large-scale. However, due to the inherent properties of solidification of each element of molten steel, particularly for high-carbon steel, internal defects such as center segregation, porosity, intermediate cracks and the like are difficult to control, and great influence is caused on the product quality.
In order to improve the internal defects of the continuous casting billet, an electromagnetic stirring technology, a heating tundish low superheat degree pouring technology, a solidification tail end pressing technology and the like are developed and successfully applied in sequence, the internal quality of the continuous casting billet is greatly improved, and particularly the solidification tail end pressing technology enables the center segregation of the continuous casting billet to control the physical leap. However, the contradiction between the large reduction action required for improving the center segregation and the reduction crack caused by the tensile stress borne by the middle area during reduction is a new difficult problem in continuous casting, and the conventional reduction process is usually difficult to obtain a continuous casting billet which has light center segregation and no internal reduction crack, especially high-carbon steel with a long solid-liquid two-phase area and a large brittle temperature range.
The publication number CN103121092A proposes a continuous casting bloom soft reduction process based on tail end electromagnetic stirring, which installs a tail end electromagnetic stirring device after a continuous casting secondary cooling area, improves the core quality of a casting blank by utilizing the dual functions of the tail end electromagnetic stirring and the soft reduction process, and can effectively avoid the problem of internal cracks caused by the tensile stress of an inner arc side.
The publication number CN101642774A proposes a bearing steel GCr15 bloom continuous casting dynamic soft reduction process, which utilizes the change of the central solid phase rate of a casting blank to control the reduction amount to solve the problems of the internal quality of the casting blank, such as central segregation, central porosity, central shrinkage cavity and the like of the bearing steel bloom.
The publication number CN102873287A proposes a continuous casting billet with a longitudinal boss, a continuous casting crystallizer copper tube and a casting and rolling method thereof, the middle part of the continuous casting billet produced by the method is provided with the longitudinal boss protruding outwards, and the boss is pressed down when the tail end is pressed down. However, the crystallizer has a complex shape and high processing requirements, and meanwhile, the foot roller has small contact area with the casting blank, insufficient supporting force and easy occurrence of steel leakage accidents.
The publication number CN107537987A proposes a convex combination roller of a continuous casting alloy steel bloom and a heavy reduction process, and internal defects of segregation, looseness, shrinkage cavity and the like can be effectively overcome by carrying out large-deformation reduction on a casting blank. However, the method has high requirements on a hydraulic system, and the improvement effect on the press crack is unknown.
Publication No. CN105618481A proposes a continuous casting billet convex roller preheating rolling device and a continuous casting billet convex roller preheating rolling process, and realizes effective improvement of the internal quality of a casting billet by utilizing continuous casting billet preheating to carry out convex roller rolling on the casting billet. However, the method has large equipment investment, and the casting blank is completely solidified and then reduced, so that the method is only effective to the defects of looseness, shrinkage cavity and the like, and cannot effectively improve the core segregation.
Many documents show that researchers work on optimization of shape and size of a continuous casting blank, particularly on a large-chamfer continuous casting blank, but research work focuses on surface quality control aspects such as corner defects of the continuous casting blank, and research on control of large square blanks, particularly internal defects, is not reported.
In conclusion, the method for controlling the internal defects of the bloom of the high-carbon chromium bearing steel is developed, the internal defects of the bloom are controlled, the continuous casting billet with light center segregation and no internal press-down cracks is obtained, and the method has an important significance for producing the high-carbon steel continuous casting billet with a long solid-liquid two-phase region and a large brittle temperature range.
Disclosure of Invention
The invention aims to provide a control method for improving the internal defects of a bloom of high-carbon chromium bearing steel. According to the invention, the problems of internal defects such as pressing cracks, center segregation and the like of the bloom of the high-carbon chromium bearing steel are solved by casting the molten steel into the bloom of the large chamfer with the liquid core, controlling continuous casting parameters and implementing the improvement and implementation of the soft reduction process of the bloom of the large chamfer with the liquid core.
In order to solve the technical problems, the invention adopts the technical scheme that: a control method for improving internal defects of a bloom of high-carbon chromium bearing steel, comprising the following steps:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 mm multiplied by 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 30-40 degrees, and the length of the bevel edge of the continuous casting blank is 45-60 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 15-30 ℃, the pulling speed to be 0.70-0.85m/min, the electromagnetic stirring current intensity of the crystallizer to be 400-500A and the frequency to be 1.2-2.4 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the single-frame pressing roller is determined by the central solid phase ratio of the bloom corresponding to the roller position, and the corresponding relation is as follows:
when the central solid phase ratio of the casting blankf S When the pressure is less than 0.3, no pressing is carried out;
when the content is less than or equal to 0.30f S When the rolling reduction is less than or equal to 0.40, the rolling reduction is 1.0 mm;
when the content is less than or equal to 0.45f S When the rolling reduction is less than or equal to 0.50, the rolling reduction is 2.0 mm;
when the content is less than or equal to 0.60f S When the rolling reduction is less than or equal to 0.65, the rolling reduction is 3.0 mm;
when the content is less than or equal to 0.75f S When the rolling reduction is less than or equal to 0.80, the rolling reduction is 4.0 mm;
when the content is less than or equal to 0.90 ≦f S When the rolling reduction is less than or equal to 0.95, the rolling reduction is 3.0 mm;
when the central solid phase rate of the casting blank at the position of the press roll is 0.40 <f S ＜0.45、0.50＜f S ＜0.60、0.65＜f S ＜0.75、0.80＜f S When the reduction is less than 0.90, the reduction is a numerical value calculated by adopting a linear interpolation method;
b. and in the static soft reduction stage, the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 1.5-2.5 mm.
In the present invention, when the central solid phase ratio is 0.95 or lessf S When the rolling reduction is less than or equal to 1.00, the rolling reduction is not fixed, which corresponds to the static soft rolling reduction stage of the following b, and whether the rolling reduction is determined by whether the previous roller is the last dynamic soft rolling reduction roller.
The high-carbon chromium bearing steel bloom produced by the control method comprises the following chemical components in percentage by mass: c: 0.95-1.05%, Si: 0.15-0.35%, Mn: 0.25-0.45%, Cr: 1.40 to 1.65 percent of Fe, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.0050 percent of Ti, and the balance of Fe and inevitable trace impurity elements.
The high-carbon chromium bearing steel bloom produced by the control method of the invention is subjected to low-power inspection: the center porosity is 0-0.5 grade, the center segregation is 0.5-1.0 grade, the shrinkage cavity is 0-0.5 grade, the intermediate crack is 0-0.5 grade, the center crack is 0-0.5 grade, and the equiaxed crystal rate is 55-68 percent.
The center carbon segregation index of the continuous casting billet produced by the control method is 0.95-1.06. The center carbon segregation index of the continuous casting billet is obtained by calculation, and the carbon segregation index C0=C/CMolten steelI.e. the ratio of the carbon content in the center of the continuous casting billet to the actual carbon content of the molten steel of the corresponding heat of the continuous casting billet.
The linear interpolation is a simple difference method, and the function y = f (x) is set at two points x0，x1Respectively is y0，y1Then function y = a0+a1x satisfies y (x)0)=y0，y(x1)=y1Then, for any point x where y = f (x) corresponds to y = f (x) = y0+(y1-y0)×[(x-x0)/(x1-x0)]。
For example: the central solid phase rate of the casting blank is 0.53, and the reduction is not more than 0.45f S Less than 0.50 and less than or equal to 0.60f S And linear interpolation calculation is carried out on the reduction corresponding to the reduction of less than 0.65. At this time, x0=0.5，y0=2.0mm（0.45≤f S Reduction amount corresponding to < 0.50), x1=0.6，y1=3.0mm（0.60≤f S < the reduction corresponding to 0.65), x = 0.53. Reduction y = y0+(y1-y0)×[(x-x0)/(x1-x0)]=2.0+（3.0-2.0）×[(0.53-0.50)/(0.60-0.50)]=2.3mm。
The central solid phase rate of the casting blank is 0.85, and the reduction is not more than 0.75f S Less than 0.80 and less than or equal to 0.90f S And linear interpolation calculation is carried out on the reduction corresponding to the reduction of less than 0.95. At this time, x0=0.8，y0=4.0mm（0.75≤f S Reduction amount corresponding to < 0.80), x1=0.9，y1=3.0mm（0.90≤f S < the reduction corresponding to 0.95), x = 0.85. Reduction y = y0+(y1-y0)×[(x-x0)/(x1-x0)]=4.0+（3.0-4.0）×[(0.85-0.80)/(0.90-0.80)]=3.5mm。
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: 1. the invention solves the problems of internal defects such as pressing cracks, center segregation and the like of the bloom of the high-carbon chromium bearing steel by casting the molten steel into the bloom with the liquid core and controlling the continuous casting parameters and optimizing the soft reduction process. 2. The invention relates to a control method for improving internal defects of a high-carbon chromium bearing steel bloom, wherein a casting blank reduction process comprises dynamic soft reduction during a certain solid phase rate and static soft reduction close to a solidification end point, the reduction efficiency of an internal area of the large-chamfer continuous casting bloom is improved due to the change of the shape of a continuous casting blank, the tensile stress of the casting blank in an intermediate area is reduced, the stress of a core part is increased, the generation of casting blank reduction cracks can be greatly reduced, the quality of the core part is improved, the static reduction close to the solidification end point is beneficial to realizing the stabilizing effect on the solidification end point of the casting blank, the core segregation level of the continuous casting blank is stabilized, and the internal quality of the continuous casting blank is improved. 3. The high-carbon chromium bearing steel bloom produced by the control method of the invention is subjected to low-power inspection: the center porosity is 0-0.5 grade, the center segregation is 0.5-1.0 grade, the shrinkage cavity is 0-0.5 grade, the intermediate crack is 0-0.5 grade, the center crack is 0-0.5 grade, and the equiaxed crystal rate is 55-68 percent; the center carbon segregation index of the continuous casting slab is 0.95-1.06.
Drawings
FIG. 1 is a schematic sectional view of a continuous casting bloom.
Wherein: 1 is an included angle between a corner of a large-chamfer continuous casting billet and a wide surface of the casting billet; 2, the length of the narrow edge of the large-chamfer continuous casting billet is shown; 3, the length of the bevel edge of the corner of the large-chamfer continuous casting billet is shown; and 4, the length of the wide edge of the large-chamfer continuous casting billet.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples.
Example 1
The control method for improving the internal defects of the bloom of the high-carbon chromium bearing steel comprises the following steps of:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 x 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 30 degrees, and the length of the bevel edge of the continuous casting blank is 60 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 15-25 ℃, the drawing speed to be 0.70m/min, the electromagnetic stirring current intensity of the crystallizer to be 400A and the frequency to be 2.4 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the roller pressed in a single frame is determined by the central solid phase rate of the bloom corresponding to the position of the roller; b. a static soft reduction stage, wherein the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 2.5 mm; the specific conditions are shown in Table 1;
table 1 example 1 center solid phase ratio and reduction at each of the rolls at the solidification end of continuous casting machine
| |
1# | 2# | 3# | 4# | 5# | 6# | 7# |
| Center solid fraction | 0.58 | 0.75 | 0.88 | 0.95 | 1.00 | 1.00 | 1.00 |
| Reduction/mm | 2.8 | 4.0 | 3.2 | 3.0 | 2.5 | 0 | 0 |
Note: 1# to 4# is dynamic soft reduction, and 5# is static soft reduction.
The macroscopic examination result of the high-carbon chromium bearing steel bloom produced by the control method for improving the internal defect of the high-carbon chromium bearing steel bloom is shown in table 2; the chemical compositions and the mass percentage of the components of the bloom of the high-carbon chromium bearing steel are shown in Table 17.
Table 2 example 1 high carbon chromium bearing steel bloom macroscopic examination results
| Serial number | Center loose (grade) | Centre segregation (grade) | Shrinkage cavity (grade) | Median crack (grade) | Center crack (grade) | Equiaxed crystal ratio (%) |
| Casting blank-1 | 0.5 | 1.0 | 0 | 0 | 0 | 58 |
| Casting blank-2 | 0.5 | 1.0 | 0 | 0.5 | 0 | 60 |
| Casting blank-3 | 0.5 | 0.5 | 0.5 | 0 | 0 | 55 |
Center carbon segregation index of continuous casting slab: 0.97-1.05.
Example 2
The control method for improving the internal defects of the bloom of the high-carbon chromium bearing steel comprises the following steps of:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 x 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 40 degrees, and the length of the bevel edge of the continuous casting blank is 45 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 20-30 ℃, the drawing speed to be 0.85m/min, the electromagnetic stirring current intensity of the crystallizer to be 500A and the frequency to be 1.2 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the roller pressed in a single frame is determined by the central solid phase rate of the bloom corresponding to the position of the roller; b. in the stage of static soft reduction, the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 1.5 mm; the specific conditions are shown in Table 3;
TABLE 3 center solid phase ratio and reduction at each of the rolls at the solidification end of example 2 continuous casting machine
| |
1# | 2# | 3# | 4# | 5# | 6# | 7# |
| Center solid fraction | 0.27 | 0.43 | 0.58 | 0.70 | 0.81 | 0.90 | 1.00 |
| Reduction/mm | 0 | 1.6 | 2.8 | 3.5 | 3.9 | 3.0 | 1.5 |
Note: 2# to 6# is dynamic soft reduction, and 7# is static soft reduction;
the macroscopic examination result of the high-carbon chromium bearing steel bloom produced by the control method for improving the internal defect of the high-carbon chromium bearing steel bloom is shown in table 4; the chemical compositions and the mass percentage of the components of the bloom of the high-carbon chromium bearing steel are shown in Table 17.
Table 4 example 2 high carbon chromium bearing steel bloom macroscopic examination results
| Serial number | Center loose (grade) | Centre segregation (grade) | Shrinkage cavity (grade) | Median crack (grade) | Center crack (grade) | Equiaxed crystal ratio (%) |
| Casting blank-1 | 0.5 | 1.0 | 0.5 | 0.5 | 0 | 64 |
| Casting blank-2 | 0.5 | 0.5 | 0 | 0.5 | 0 | 65 |
| Casting blank-3 | 0.5 | 0.5 | 0 | 0 | 0 | 68 |
Center carbon segregation index of continuous casting slab: 0.96-1.06.
Example 3
The control method for improving the internal defects of the bloom of the high-carbon chromium bearing steel comprises the following steps of:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 mm multiplied by 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 32 degrees, and the length of the bevel edge of the continuous casting blank is 50 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 18-23 ℃, the drawing speed to be 0.75m/min, the electromagnetic stirring current intensity of the crystallizer to be 430A and the frequency to be 1.5 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the roller pressed in a single frame is determined by the central solid phase rate of the bloom corresponding to the position of the roller; b. in the stage of static soft reduction, the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 1.8 mm; the details are shown in Table 5;
TABLE 5 example 3 center solid phase ratio and reduction at each of the rolls at the solidification end of the continuous casting machine
| |
1# | 2# | 3# | 4# | 5# | 6# | 7# |
| Center solid fraction | 0.47 | 0.63 | 0.77 | 0.89 | 0.97 | 1.0 | 1.0 |
| Reduction/mm | 2.0 | 3.0 | 4.0 | 3.1 | 1.8 | 0 | 0 |
Note: 1# to 4# is dynamic soft reduction, and 5# is static soft reduction;
the macroscopic examination result of the high-carbon chromium bearing steel bloom produced by the control method for improving the internal defect of the high-carbon chromium bearing steel bloom is shown in table 6; the chemical compositions and the mass percentage of the components of the bloom of the high-carbon chromium bearing steel are shown in Table 17.
Table 6 example 3 high carbon chromium bearing steel bloom macroscopic examination results
| Serial number | Center loose (grade) | Centre segregation (grade) | Shrinkage cavity (grade) | Median crack (grade) | Center crack (grade) | Equiaxed crystal ratio (%) |
| Casting blank-1 | 0.5 | 0.5 | 0 | 0 | 0.5 | 55 |
| Casting blank-2 | 0.5 | 0.5 | 0.5 | 0.5 | 0 | 59 |
| Casting blank-3 | 0 | 0.5 | 0.5 | 0 | 0 | 62 |
Center carbon segregation index of continuous casting slab: 0.95-1.05.
Example 4
The control method for improving the internal defects of the bloom of the high-carbon chromium bearing steel comprises the following steps of:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 x 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 36 degrees, and the length of the bevel edge of the continuous casting blank is 55 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 20-25 ℃, the drawing speed to be 0.80m/min, the electromagnetic stirring current intensity of the crystallizer to be 480A and the frequency to be 2.0 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the roller pressed in a single frame is determined by the central solid phase rate of the bloom corresponding to the position of the roller; b. in the stage of static soft reduction, the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 1.5 mm; the details are shown in Table 7;
TABLE 7 example 4 center solid phase ratio and reduction at each of the rolls at the solidification end of continuous casting machine
| |
1# | 2# | 3# | 4# | 5# | 6# | 7# |
| Center solid fraction | 0.36 | 0.53 | 0.68 | 0.81 | 0.91 | 0.95 | 1.00 |
| Reduction/mm | 1.0 | 2.3 | 3.3 | 3.9 | 3.0 | 3.0 | 1.5 |
Note: 1# to 6# is dynamic soft reduction, and 7# is static soft reduction;
the macroscopic examination result of the high-carbon chromium bearing steel bloom produced by the control method for improving the internal defect of the high-carbon chromium bearing steel bloom is shown in table 8; the chemical compositions and the mass percentage of the components of the bloom of the high-carbon chromium bearing steel are shown in Table 17.
TABLE 8 EXAMPLE 4 high-carbon chromium bearing Steel bloom Low-power test results
| Serial number | Center loose (grade) | Centre segregation (grade) | Shrinkage cavity (grade) | Median crack (grade) | Center crack (grade) | Equiaxed crystal ratio (%) |
| Casting blank-1 | 0 | 0.5 | 0.5 | 0.5 | 0 | 68 |
| Casting blank-2 | 0.5 | 0.5 | 0 | 0.5 | 0.5 | 63 |
| Casting blank-3 | 0.5 | 0.5 | 0 | 0 | 0 | 62 |
Center carbon segregation index of continuous casting slab: 0.95-1.04.
Example 5
The control method for improving the internal defects of the bloom of the high-carbon chromium bearing steel comprises the following steps of:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 mm multiplied by 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 35 degrees, and the length of the bevel edge of the continuous casting blank is 57 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 16-19 ℃, the drawing speed to be 0.83m/min, the electromagnetic stirring current intensity of the crystallizer to be 450A and the frequency to be 1.8 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the roller pressed in a single frame is determined by the central solid phase rate of the bloom corresponding to the position of the roller; b. in the stage of static soft reduction, the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 1.5 mm; the details are shown in Table 9;
TABLE 9 center solid phase ratio and reduction at each of the rolls at the solidification end of example 5 continuous casting machine
| |
1# | 2# | 3# | 4# | 5# | 6# | 7# |
| Center solid fraction | 0.29 | 0.45 | 0.60 | 0.73 | 0.83 | 0.91 | 1.00 |
| Reduction/mm | 0 | 2.0 | 3.0 | 3.8 | 3.7 | 3.0 | 1.5 |
Note: 2# to 6# is dynamic soft reduction, and 7# is static soft reduction;
the macroscopic examination result of the high-carbon chromium bearing steel bloom produced by the control method for improving the internal defect of the high-carbon chromium bearing steel bloom is shown in table 10; the chemical compositions and the mass percentage of the components of the bloom of the high-carbon chromium bearing steel are shown in Table 17.
TABLE 10 EXAMPLE 5 high carbon chromium bearing Steel bloom Low magnification test results
| Serial number | Center loose (grade) | Centre segregation (grade) | Shrinkage cavity (grade) | Median crack (grade) | Center crack (grade) | Equiaxed crystal ratio (%) |
| Casting blank-1 | 0 | 0.5 | 0 | 0 | 0 | 59 |
| Casting blank-2 | 0.5 | 0.5 | 0 | 0 | 0 | 62 |
| Casting blank-3 | 0.5 | 0.5 | 0.5 | 0.5 | 0 | 60 |
Center carbon segregation index of continuous casting slab: 0.97-1.05.
Example 6
The control method for improving the internal defects of the bloom of the high-carbon chromium bearing steel comprises the following steps of:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 x 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 38 degrees, and the length of the bevel edge of the continuous casting blank is 48 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 17-21 ℃, the drawing speed to be 0.72m/min, the electromagnetic stirring current intensity of the crystallizer to be 415A and the frequency to be 2.3 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the roller pressed in a single frame is determined by the central solid phase rate of the bloom corresponding to the position of the roller; b. a static soft reduction stage, wherein the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 2.0 mm; the details are shown in Table 11;
TABLE 11 example 6 center solid phase ratio and reduction at each of the rolls at the solidification end of continuous casting machine
| |
1# | 2# | 3# | 4# | 5# | 6# | 7# |
| Center solid fraction | 0.60 | 0.75 | 0.88 | 0.94 | 0.99 | 1.0 | 1.0 |
| Reduction/mm | 3.00 | 4.0 | 3.2 | 3.0 | 2.0 | 0 | 0 |
Note: 1# to 2# is dynamic soft reduction, and 5# is static soft reduction;
the macroscopic examination result of the high-carbon chromium bearing steel bloom produced by the control method for improving the internal defect of the high-carbon chromium bearing steel bloom is shown in table 12; the chemical compositions and the mass percentage of the components of the bloom of the high-carbon chromium bearing steel are shown in Table 17.
TABLE 12 EXAMPLE 6 high carbon chromium bearing Steel bloom Low magnification test results
| Serial number | Center loose (grade) | Centre segregation (grade) | Shrinkage cavity (grade) | Median crack (grade) | Center crack (grade) | Equiaxed crystal ratio (%) |
| Casting blank-1 | 0.5 | 1.0 | 0.5 | 0 | 0 | 59 |
| Casting blank-2 | 0.5 | 0.5 | 0.5 | 0 | 0 | 62 |
| Casting blank-3 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 61 |
Center carbon segregation index of continuous casting slab: 0.98-1.06.
Example 7
The control method for improving the internal defects of the bloom of the high-carbon chromium bearing steel comprises the following steps of:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 mm multiplied by 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 39 degrees, and the length of the bevel edge of the continuous casting blank is 53 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 26-29 ℃, the drawing speed to be 0.81m/min, the electromagnetic stirring current intensity of the crystallizer to be 465A and the frequency to be 1.4 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the roller pressed in a single frame is determined by the central solid phase rate of the bloom corresponding to the position of the roller; b. a static soft reduction stage, wherein the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 2.0 mm; the details are shown in Table 13;
TABLE 13 center solid phase ratio and reduction at each of the rolls at the solidification end of example 7 continuous casting machine
| |
1# | 2# | 3# | 4# | 5# | 6# | 7# |
| Center solid fraction | 0.34 | 0.51 | 0.65 | 0.78 | 0.88 | 0.95 | 1.00 |
| Reduction/mm | 1.0 | 2.1 | 3.0 | 4.0 | 3.2 | 2.0 | 0 |
Note: 1# to 5# is dynamic soft reduction, and 6# is static soft reduction;
the macroscopic examination result of the high-carbon chromium bearing steel bloom produced by the control method for improving the internal defect of the high-carbon chromium bearing steel bloom is shown in table 14; the chemical compositions and the mass percentage of the components of the bloom of the high-carbon chromium bearing steel are shown in Table 17.
TABLE 14 low power test results for example 7 high carbon chromium bearing steel bloom
| Serial number | Center loose (grade) | Centre segregation (grade) | Shrinkage cavity (grade) | Median crack (grade) | Center crack (grade) | Equiaxed crystal ratio (%) |
| Casting blank-1 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 57 |
| Casting blank-2 | 0.5 | 0.5 | 0 | 0 | 0 | 58 |
| Casting blank-3 | 0.5 | 0.5 | 0 | 0 | 0 | 60 |
Center carbon segregation index of continuous casting slab: 0.97-1.05.
Example 8
The control method for improving the internal defects of the bloom of the high-carbon chromium bearing steel comprises the following steps of:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 x 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 31 degrees, and the length of the bevel edge of the continuous casting blank is 46 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 22-27 ℃, the drawing speed to be 0.73m/min, the electromagnetic stirring current intensity of the crystallizer to be 425A and the frequency to be 1.6 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the roller pressed in a single frame is determined by the central solid phase rate of the bloom corresponding to the position of the roller; b. a static soft reduction stage, wherein the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 2.0 mm; the details are shown in Table 15;
TABLE 15 center solid phase ratio and reduction at each of the rolls at the solidification end of example 8 continuous casting machine
| |
1# | 2# | 3# | 4# | 5# | 6# | 7# |
| Center solid fraction | 0.58 | 0.75 | 0.87 | 0.94 | 0.99 | 1.0 | 1.0 |
| Reduction/mm | 2.8 | 4.0 | 3.3 | 3.0 | 2.0 | 0 | 0 |
Note: 1# to 4# is dynamic soft reduction, and 5# is static soft reduction;
the macroscopic examination result of the high-carbon chromium bearing steel bloom produced by the control method for improving the internal defect of the high-carbon chromium bearing steel bloom is shown in table 16; the chemical compositions and the mass percentage of the components of the bloom of the high-carbon chromium bearing steel are shown in Table 17.
TABLE 16 Low-magnification test results for bloom of high-carbon chromium bearing steel in example 8
| Serial number | Center loose (grade) | Centre segregation (grade) | Shrinkage cavity (grade) | Median crack (grade) | Center crack (grade) | Equiaxed crystal ratio (%) |
| Casting blank-1 | 0.5 | 1.0 | 0.5 | 0 | 0 | 59 |
| Casting blank-2 | 0.5 | 1.0 | 0.5 | 0 | 0 | 60 |
| Casting blank-3 | 0.5 | 0.5 | 0.5 | 0.5 | 0 | 61 |
Center carbon segregation index of continuous casting slab: 0.96-1.06.
TABLE 17 chemical compositions and mass percents of compositions (%)
| Examples | C | Si | Mn | Cr | | S | Ti | |
| 1 | 1.02 | 0.22 | 0.29 | 1.42 | 0.019 | 0.012 | 0.0028 | |
| 2 | 0.97 | 0.19 | 0.32 | 1.47 | 0.023 | 0.009 | 0.0032 | |
| 3 | 0.99 | 0.28 | 0.37 | 1.53 | 0.015 | 0.017 | 0.0041 | |
| 4 | 1.04 | 0.17 | 0.42 | 1.40 | 0.016 | 0.011 | 0.0049 | |
| 5 | 1.01 | 0.31 | 0.25 | 1.58 | 0.013 | 0.015 | 0.0037 | |
| 6 | 0.95 | 0.35 | 0.40 | 1.65 | 0.020 | 0.013 | 0.0050 | |
| 7 | 1.03 | 0.20 | 0.34 | 1.63 | 0.010 | 0.020 | 0.0043 | |
| 8 | 1.05 | 0.15 | 0.45 | 1.56 | 0.025 | 0.018 | 0.0031 |
The balance of the ingredients in table 17 is Fe and inevitable trace impurity elements.
The control method for the internal defects of the bloom of the high-carbon chromium bearing steel in the embodiment realizes the control of the internal defects of the bloom and obtains the continuous casting billet which has light center segregation and no internal press-down cracks.
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.
Claims (2)
1. A control method for improving internal defects of a bloom of high-carbon chromium bearing steel is characterized by comprising the following steps:
(1) casting molten steel into a large chamfer angle bloom with a liquid core: the size of the continuous casting blank is 280 mm multiplied by 325mm, the included angle between the corner of the continuous casting blank and the wide surface of the casting blank is controlled to be 30-40 degrees, and the length of the bevel edge of the continuous casting blank is 45-60 mm;
(2) controlling continuous casting parameters: controlling the superheat degree of molten steel in the tundish to be 15-30 ℃, the pulling speed to be 0.70-0.85m/min, the electromagnetic stirring current intensity of the crystallizer to be 400-500A and the frequency to be 1.2-2.4 Hz;
(3) the method comprises the following steps of carrying out soft pressing on a large chamfer angle bloom with a liquid core, wherein the soft pressing is divided into a dynamic pressing stage and a static pressing stage:
a. in the dynamic soft pressing stage, the pressing amount of the single-frame pressing roller is determined by the central solid phase ratio of the bloom corresponding to the roller position, and the corresponding relation is as follows:
when the central solid phase rate fS of the casting blank is less than 0.3, no reduction is carried out;
when fS is more than or equal to 0.30 and less than or equal to 0.40, the reduction is 1.0 mm;
when fS is more than or equal to 0.45 and less than or equal to 0.50, the reduction is 2.0 mm;
when fS is more than or equal to 0.60 and less than or equal to 0.65, the reduction is 3.0 mm;
when fS is more than or equal to 0.75 and less than or equal to 0.80, the reduction is 4.0 mm;
when fS is more than or equal to 0.90 and less than or equal to 0.95, the reduction is 3.0 mm;
when the central solid phase rate of the casting blank at the position of the rolling roller is more than 0.40 and less than 0.45, more than 0.50 and less than 0.60, more than 0.65 and less than 0.75 and more than 0.80 and less than 0.90, the rolling reduction is a numerical value calculated by adopting a linear interpolation method;
b. in the stage of static soft reduction, the reduction is only carried out at the next roller of the last dynamic soft-pressing lower roller, and the reduction is 1.5-2.5 mm;
the center carbon segregation index of the continuous casting billet produced by the control method is 0.96-1.06;
the high-carbon chromium bearing steel bloom produced by the control method is subjected to low-power inspection: the center porosity is 0-0.5 grade, the center segregation is 0.5-1.0 grade, the shrinkage cavity is 0-0.5 grade, the intermediate crack is 0-0.5 grade, the center crack is 0-0.5 grade, and the equiaxed crystal rate is 55-68 percent.
2. The control method for improving the internal defects of the high-carbon chromium bearing steel bloom as claimed in claim 1, wherein the high-carbon chromium bearing steel bloom produced by the control method comprises the following chemical components in percentage by mass: c: 0.95-1.05%, Si: 0.15-0.35%, Mn: 0.25-0.45%, Cr: 1.40 to 1.65 percent of Fe, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.0050 percent of Ti, and the balance of Fe and inevitable trace impurity elements.
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| CN110777300B (en) * | 2019-12-05 | 2020-11-27 | 宝钢特钢韶关有限公司 | Method for manufacturing high-carbon chromium bearing steel |
| CN111136228A (en) * | 2020-01-07 | 2020-05-12 | 邢台钢铁有限责任公司 | Control method for improving transverse cracks of corners of continuous casting billet |
| CN112662832A (en) * | 2020-12-18 | 2021-04-16 | 芜湖新兴铸管有限责任公司 | Production method of special-section square billet of high-carbon chromium bearing steel |
| CN114012055B (en) * | 2021-11-11 | 2023-05-19 | 建龙北满特殊钢有限责任公司 | Continuous casting process of rectangular bloom of high-homogeneity high-carbon chromium bearing steel |
| CN114734010A (en) * | 2022-03-18 | 2022-07-12 | 首钢京唐钢铁联合有限责任公司 | Production method for thin slab continuous casting and rolling on-line casting blank thinning |
| CN114769540B (en) * | 2022-04-26 | 2023-06-20 | 武汉钢铁有限公司 | Production method of high-grade non-oriented silicon steel casting blank |
| CN117226059B (en) * | 2023-11-15 | 2024-01-26 | 北京科技大学 | Reduction control method for improving macro-segregation and semi-macro-segregation of high-carbon low-alloy steel |
| CN117272761A (en) * | 2023-11-21 | 2023-12-22 | 北京科技大学 | Method and system for monitoring middle cracks of bloom |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63242453A (en) * | 1987-03-30 | 1988-10-07 | Nkk Corp | Method for casting by light rolling reduction |
| EP1088610A1 (en) * | 1999-09-29 | 2001-04-04 | SMS Demag AG | Process and device for the production of continuously cast steel products |
| EP1132161A1 (en) * | 2000-03-10 | 2001-09-12 | SMS Demag AG | Process for continuous casting slabs, especially thin slabs |
| CN1393308A (en) * | 2001-06-29 | 2003-01-29 | 中国冶金建设集团包头钢铁设计研究总院 | Light pressing method and apparatus for conticast |
| CN1449877A (en) * | 2002-04-08 | 2003-10-22 | 住友金属工业株式会社 | Continuous casting method, continuous casting device and continuous casting blanket |
| CN101642774A (en) * | 2009-09-15 | 2010-02-10 | 邢台钢铁有限责任公司 | GCr15 bearing steel bloom continuous casting dynamic soft reduction process |
| CN101648263A (en) * | 2009-09-15 | 2010-02-17 | 邢台钢铁有限责任公司 | Bloom continuous casting dynamic soft reduction process for high-quality tire cord steel |
-
2019
- 2019-08-29 CN CN201910809310.0A patent/CN110523942B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63242453A (en) * | 1987-03-30 | 1988-10-07 | Nkk Corp | Method for casting by light rolling reduction |
| EP1088610A1 (en) * | 1999-09-29 | 2001-04-04 | SMS Demag AG | Process and device for the production of continuously cast steel products |
| EP1132161A1 (en) * | 2000-03-10 | 2001-09-12 | SMS Demag AG | Process for continuous casting slabs, especially thin slabs |
| CN1393308A (en) * | 2001-06-29 | 2003-01-29 | 中国冶金建设集团包头钢铁设计研究总院 | Light pressing method and apparatus for conticast |
| CN1449877A (en) * | 2002-04-08 | 2003-10-22 | 住友金属工业株式会社 | Continuous casting method, continuous casting device and continuous casting blanket |
| CN101642774A (en) * | 2009-09-15 | 2010-02-10 | 邢台钢铁有限责任公司 | GCr15 bearing steel bloom continuous casting dynamic soft reduction process |
| CN101648263A (en) * | 2009-09-15 | 2010-02-17 | 邢台钢铁有限责任公司 | Bloom continuous casting dynamic soft reduction process for high-quality tire cord steel |
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