CN112139240B - Production method for reducing performance line difference of reinforcing steel bar - Google Patents
Production method for reducing performance line difference of reinforcing steel bar Download PDFInfo
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- CN112139240B CN112139240B CN202010803077.8A CN202010803077A CN112139240B CN 112139240 B CN112139240 B CN 112139240B CN 202010803077 A CN202010803077 A CN 202010803077A CN 112139240 B CN112139240 B CN 112139240B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
- B21B1/18—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section in a continuous process
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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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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
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- 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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Abstract
The invention provides a production method for reducing the performance linear difference of a reinforcing steel bar, which comprises the following steps: step A: controlling the components of the steel bar blank: carbon: 0.18% -0.25%, silicon: 0.20-0.80%, manganese: 1.20-1.60 percent of phosphorus, less than or equal to 0.0045 percent of phosphorus and less than or equal to 0.0045 percent of sulfur; and B: rolling the reinforcing steel bars with the specification of phi 12-phi 20mm by adopting a three-slitting or four-slitting process, wherein in the three-slitting or four-slitting process, the hole types of a precutting hole K4, a slitting hole K3, a finished product front hole K2 and a finished product hole K1 meet the requirements on design and manufacture: in each hole type, the middle hole is larger than the two side holes by 3 percent of the inner diameter of the hole. The invention reduces the performance fluctuation of each line and improves the performance stability of the reinforcing steel bar.
Description
Technical Field
The invention relates to the field of steel rolling, in particular to a production method for reducing the mechanical property line difference of each line after steel bars are cut, namely a production method for reducing the steel bar property line difference.
Background
In order to improve the yield and the production efficiency of the small-size steel bars and realize energy conservation and consumption reduction, the slitting rolling technology is mostly adopted for the steel bar production. At present, steel bars with the diameter of 25 mm and below in China tend to be produced by adopting a cutting mode of two-cutting, three-cutting, four-cutting and the like according to different specifications, the yield of the steel bars produced by adopting the cutting process can be improved by 10-30%, and correspondingly, the energy consumption can be reduced by 10-20% at the same time, so that the steel bars produced by adopting the cutting process in China are generally produced by adopting the cutting process, especially the steel bars with small specifications.
The size line difference control is one of the difficulties of splitting rolling when the steel bar is produced by adopting a splitting process, the size line difference can cause the size and weight deviation to be over poor and can also cause the performance of the steel bar to fluctuate, the situation generally causes the attention of people and controls the situation in a key way, if Zheng Fu print and the like research the four-splitting size line difference and the control method of the steel bar, the Mongolian analysis solves the splitting process difficulties such as the five-line splitting size line difference of the steel bar with the diameter of 10mm, and the Shao International et al analyzes and controls the 12mm five-splitting performance line difference of the steel bar of Xinjiang Kunyu iron and steel Limited company from the aspects of cooling control, size line difference and the like. At present, the control means for the dimension line difference of the reinforcing steel bars and the related technology application are relatively mature.
However, in production, even if the reinforcing steel bars with better control of the size line difference of the divided reinforcing steel bars and small size line difference are found, the performance of the reinforcing steel bars, particularly the strength difference of the reinforcing steel bars, still has larger difference, particularly the reinforcing steel bars adopting the three-division and four-division processes.
In summary, the following problems exist in the prior art: under the condition that the size and weight deviation are basically consistent, the performance of the steel bars among the lines is fluctuated, and the mechanical performance line difference of the steel bars is large.
Disclosure of Invention
The invention provides a production method for reducing the performance line difference of a reinforcing steel bar, which aims to solve the problems that the performance of the reinforcing steel bar between each two split lines is fluctuated, and the mechanical performance line difference of each line of the reinforcing steel bar is large.
Therefore, the invention provides a production method for reducing the performance line difference of the reinforcing steel bar, which comprises the following steps of:
step A: controlling the components of the steel bar blank: carbon: 0.18% -0.25%, silicon: 0.20-0.80%, manganese: 1.20-1.60 percent of phosphorus, less than or equal to 0.0045 percent of phosphorus and less than or equal to 0.0045 percent of sulfur;
and B: rolling the reinforcing steel bars with the specification of phi 12-phi 20mm by adopting a three-slitting or four-slitting process, wherein in the three-slitting or four-slitting process, the hole types of a precutting hole K4, a slitting hole K3, a finished product front hole K2 and a finished product hole K1 meet the requirements on design and manufacture:
in each hole type, the middle hole is used for amplifying the inner diameter of the hole according to 3 percent than the two side holes;
and C: heating the steel bar rolling blank in the furnace for 60-90 min, adopting three-stage heating, controlling the temperature of a soaking section at 1150 +/-40 ℃, controlling the initial rolling temperature at 1040 +/-30 ℃, heating the blank, rolling the blank by a rough, medium and finish rolling tandem mill set, controlling the rolling speed of a finished product rack at 10-15 m/s, and controlling the temperature of an upper cooling bed to be more than or equal to 920 ℃.
Furthermore, the inner diameter of the hole is enlarged by 3% in the middle of the four-split two-line holes compared with the holes at the two sides of the four-split two-line holes, so that the weight deviation of the two-line reinforcing steel bar in the middle of the four-split two-line holes is 2.5-3.5% larger than that of the two-line reinforcing steel bar at the side under the condition of ensuring the normal control of the material type in the rolling process.
Furthermore, the inner diameter of the hole in the middle of the three-segmentation is enlarged by 3 percent compared with the inner diameter of the holes at two sides of the three-segmentation, so that the weight deviation of the middle line of the three-segmentation is 2.5 to 3.5 percent larger than that of the two-line steel bar at the side surface under the condition of ensuring the normal control of the material type in the rolling process.
Further, in the step a, the carbon: 0.24%, silicon: 0.55%, manganese: 1.34%, phosphorus: 0.023%, sulfur: 0.028 percent.
Further, in the step B, the billet is heated in the furnace for 65min by adopting three-section heating, the temperature of a soaking section is controlled according to 1150 +/-40 ℃, the initial rolling temperature is 1050 ℃, a four-segmentation process and a hole pattern system are adopted, the rolling speed of a finished product rack is controlled at 13m/s, and the temperature of a finished product rack is 960 ℃.
Further, in the step a, the carbon: 0.23%, silicon: 0.46%, manganese: 1.44%, phosphorus: 0.026%, sulfur: 0.027 percent.
Further, in the step B, the billet is heated in the furnace for 62min by adopting three-section heating, the temperature of a soaking section is controlled according to 1150 +/-40 ℃, the initial rolling temperature is 1060 ℃, a three-segmentation process and a pass system are adopted, the rolling speed of a finished product rack is controlled at 13m/s, and the temperature of an upper cooling bed is 980 ℃.
Further, the invention also provides a split steel bar with small performance line difference, and the split steel bar comprises the following components: carbon: 0.18% -0.25%, silicon: 0.20-0.80%, manganese: 1.20-1.60 percent of phosphorus, less than or equal to 0.0045 percent of phosphorus, and less than or equal to 0.0045 percent of sulfur;
after splitting, the weight deviation of the reinforcing steel bars of the middle line is 2.5-3.5% larger than that of the reinforcing steel bars of the two lines on the side surface.
Furthermore, the split steel bars with small performance line difference are four split steel bars, and after the split steel bars are split, the weight deviation of the steel bars on the two middle lines of the split line is 2.5-3.5% larger than that of the steel bars on the two side lines of the split line.
Furthermore, the segmented steel bars with small performance line difference are three segmented steel bars, and after segmentation, the weight deviation of the steel bars in the middle line on the segmented line is 2.5-3.5% larger than that of the steel bars in the two lines on the side surface.
By means of proper steel bar component control, combined with the change of the splitting hole pattern design, the strength of the steel bar is improved by increasing weight deviation, the strength reduction caused by steel quality of the three-split middle first-line steel bar and the four-split middle second-line steel bar is compensated, after the technology is adopted, the HRB 400-grade steel bar with the specification of phi 12-phi 20mm and adopting the three-split and four-split processes is adopted, the strength difference of the split steel bars of all lines is reduced to be below 0-15 MPa from 0-25 MPa, the performance fluctuation of the split lines is greatly reduced, and the performance stability of the steel bar is improved.
1. The niobium-added steel bar has four cutting performances:
the yield strength is 420-465 MPa, and the average value is 443MPa;
poor same batch property line (yield strength): 0 to 15MPa; the average value was 6MPa.
The niobium-added steel bar has three cutting performances:
the yield strength is 425-465 MPa, and the average value is 448MPa;
poor same batch property line (yield strength): 0 to 10MPa; the average value was 4MPa.
2. The vanadium (nitrogen) added steel bar has four cutting performances:
the yield strength is 420-475 MPa, and the average value is 456MPa;
poor same batch property line (yield strength): 0 to 15MPa; the average value was 5MPa.
Three-cutting performance of vanadium (nitrogen) added steel bars:
the yield strength is 420-480 MPa, and the average value is 453MPa;
poor same batch property line (yield strength): 0 to 10MPa; the average value was 4MPa.
Drawings
FIG. 1 is a schematic diagram of the hole pattern of a pre-cutting hole K7 adopted by the invention;
FIG. 2 is a schematic diagram of the hole pattern of a front hole K6 adopted in the present invention;
FIG. 3 is a schematic diagram of the hole pattern of the pre-cutting hole K5 adopted in the present invention;
FIG. 4 is a schematic diagram of the hole pattern of the pre-cut hole K4 adopted in the present invention;
FIG. 5 is a schematic diagram of the hole pattern of the cutting hole K3 adopted in the present invention;
fig. 6 is a schematic diagram of the hole pattern of the finished front hole K2 used in the present invention, wherein only one of the plurality of cutting holes is shown;
fig. 7 is a schematic diagram of the hole pattern of the finished hole K1 used in the present invention, in which only one of the plurality of cutting holes is shown.
Detailed Description
In order to more clearly understand the technical features, objects, and effects of the present invention, the present invention will now be described with reference to the accompanying drawings.
The applicant finds that even if the reinforcing steel bars with better control of the size line difference of the reinforcing steel bars and small size line difference are cut, the performance of the reinforcing steel bars, particularly the strength difference of the reinforcing steel bars, still has larger difference, particularly the reinforcing steel bars adopting the three-cutting and four-cutting processes, mainly because: the inevitable defects of central looseness, central segregation and the like in the central area of the cross section of the blank and the coarse crystal area are not evenly distributed to all lines after rolling and splitting, namely, the steel quality of the steel bars of all lines is different, so that the performance of the steel bars is influenced.
The steel bar is generally produced by rolling a continuous casting square billet, the macroscopic structure of the cross section of the square billet is extremely uneven in distribution and generally consists of three parts, namely edge fine equiaxed crystals, middle columnar crystals and core coarse equiaxed crystals; the most common defects of the square billet comprise different grades, inevitable center porosity and center segregation, if the control is not proper, the defects of shrinkage cavity, corner and middle cracks, inclusion, surface pores and the like can also occur, and solute elements such as C, mn, P, S and the like are generally segregated in the center of the billet. Therefore, the distribution of the structure and defects of the blank itself in the cross section is very uneven, and even in a blank of a normal quality, the steel quality of the central region is greatly different from that of other portions.
The common cutting modes of the steel bars at present mainly comprise three cutting, four cutting and the like of two cutting and multi-line cutting. Taking a four-slit system as an example, as shown in fig. 1, fig. 2, fig. 3, fig. 4, fig. 5, fig. 6 and fig. 7, the four-slit system mainly includes pre-slit holes K5 to K7, pre-slit hole K4, slit hole K3, pre-product hole K2 and product hole K1. As shown in fig. 1, 2 and 3, as can be seen from the four-slit hole system, the holes before slitting are elliptical holes, rectangular holes or box-shaped holes, and compared with the blanks, the rolled pieces before slitting have no obvious change in the structures and defect positions of the blanks, and the centers are loose and are still segregated at the center of the rolled pieces; when the rolled piece passes through the pre-cut hole and the splitting hole, the rolled piece is flattened and split, when splitting is finished, the center loose and center segregation band of the blank is mainly distributed to the middle two lines after splitting, and the two lines on the side surface are mainly formed by metal flows of fine equiaxed crystals and middle columnar crystals on the edge of the blank, so that the structures and the defects of the metal flows of the middle two lines and the two lines on the side surface after the rolled piece is four-split are obviously different due to the uneven distribution of the structures and the defects of the blank on the cross section. Similarly, for three-segmentation, the steel quality difference between the middle line and the two lines on the side surface is large after the three-segmentation; for the second segmentation, the steel quality of two lines after the segmentation is not very different.
Under the condition that the size and weight deviation are basically consistent, because of the steel quality difference between different splitting lines, the strength of the middle line of the three splitting and the strength of the middle two lines of the four splitting are both obviously reduced compared with the strength of the two lines on the side surface, taking HRB400E as an example, the strength of the middle line of the three splitting and the strength of the middle two lines of the four splitting are both reduced by 12-16 MPa compared with the yield strength of the two lines on the side surface, the reduction range is 2.5-3.5%, the steel quality of the two lines of the two splitting is relatively consistent, the yield strength difference is about 5MPa, and the strength fluctuation is within 1%. When the weight deviation of the middle first line of the three-segmentation and the middle two lines of the four-segmentation is relatively small, namely the strength reduction caused by the weight deviation is superposed with the strength reduction caused by steel, the strength reduction value of the steel bars of the middle first line of the three-segmentation and the middle two lines of the four-segmentation can reach 25MPa to the maximum compared with the strength reduction value of the steel bars of the two lines of the side surface.
Based on the above analysis, the applicant found that: the performance of the steel bars fluctuates due to the inconsistent steel quality among the cutting lines.
Therefore, the invention provides a production method for reducing the performance line difference of the reinforcing steel bar, which comprises the following steps of:
step A: controlling the components of the steel bar blank: the components of the segmented reinforcing steel bar are as follows: carbon: 0.18% -0.25%, silicon: 0.20-0.80%, manganese: 1.20-1.60 percent of phosphorus, less than or equal to 0.0045 percent of phosphorus and less than or equal to 0.0045 percent of sulfur;
and B: rolling the steel bars with the specification of phi 12-phi 20mm by adopting a three-slitting or four-slitting process, wherein in the three-slitting or four-slitting process, the hole patterns of a precutting hole K4, a slitting hole K3, a finished product front hole K2 and a finished product hole K1 meet the requirements on design and manufacture:
in each hole pattern, as shown in fig. 4, 5, 6 and 7, the middle hole enlarges the inner diameter of the hole by 3 percent compared with the two side holes; under the condition of ensuring the normal control of the material type in the rolling process, the weight deviation of the four-split middle second wire and the three-split middle first wire is 2.5 to 3.5 percent larger than that of the two-wire steel bars on the side surface;
and C: the billet for rolling the reinforcing steel bar is heated in a furnace for 60-90 min by adopting three-section heating, the temperature of a soaking section is controlled according to 1150 +/-40 ℃, the initial rolling temperature is controlled at 1040 +/-30 ℃, the billet is heated and then is rolled by a rough, medium and finish rolling continuous rolling unit, the rolling speed of a finished product rack is controlled at 10-15 m/s, and the temperature of an upper cooling bed is more than or equal to 920 ℃.
Sampling a finished product: 5 samples are respectively cut on different cutting lines of the steel bars, and the sample length is 500-550 mm.
Measuring and calculating the weight deviation of each cut line according to the requirement of 8.4 in the GB/T1499.2-2018 standard; 1 sample of each cut line is directly subjected to a tensile test according to the GB/T28900 standard without processing.
Further, in the step A: controlling the components of the steel bar blank: the components of the segmented reinforcing steel bar are as follows: carbon: 0.18% -0.25%, silicon: 0.20-0.80%, manganese: 1.20-1.60 percent of phosphorus, less than or equal to 0.0045 percent of phosphorus, and less than or equal to 0.0045 percent of sulfur; niobium: 0.023% -0.033% or
Carbon: 0.18% -0.25%, silicon: 0.20-0.80%, manganese: 1.20-1.60 percent of phosphorus, less than or equal to 0.0045 percent of phosphorus and less than or equal to 0.0045 percent of sulfur; niobium: 0.023% -0.033% and vanadium: 0.022% -0.034%, nitrogen: 0.0080% -0.0110%;
by controlling components and changing the design of splitting holes, the strength of the steel bar is improved by increasing weight deviation, the strength reduction caused by steel quality of the steel bar with the diameter of 12-20 mm and the HRB 400-grade steel bar adopting the three-splitting and four-splitting processes is compensated, the strength difference of the steel bar of each line after splitting is reduced from 0-25 MPa to below 0-15 MPa, the performance fluctuation of each line after splitting is greatly reduced, and the performance stability of the steel bar is improved.
Furthermore, the inner diameter of the hole is enlarged by 3% in the middle of the four-split two-line holes compared with the holes at the two sides of the four-split two-line holes, so that the weight deviation of the two-line reinforcing steel bar in the middle of the four-split two-line holes is 2.5-3.5% larger than that of the two-line reinforcing steel bar at the side under the condition of ensuring the normal control of the material type in the rolling process.
Furthermore, the inner diameter of the hole in the middle of the three-segmentation is enlarged by 3 percent compared with the inner diameter of the holes at two sides of the three-segmentation, so that the weight deviation of the middle line of the three-segmentation is 2.5 to 3.5 percent larger than that of the two-line steel bar at the side surface under the condition of ensuring the normal control of the material type in the rolling process.
Example 1
The steel bar with the diameter of 12mm and the HRB400E is produced by a four-segmentation process according to the GB/T1499.2-2018 standard, and the concrete steps are as follows:
1) Controlling smelting components of the blank: carbon: 0.24%, silicon: 0.55%, manganese: 1.34%, phosphorus: 0.023%, sulfur: 0.028%, niobium: 0.025 percent;
2) Pre-cut holes K4 and cut holes K3 in the rolling process, and hole pattern design and manufacturing requirements of a front finished product hole K2 and a finished product hole K1 are as follows: the inner diameter of the hole is enlarged by 3 percent compared with the two side holes in the middle of the four-segmentation;
3) Heating the billet in the furnace for 65min by adopting three-section heating, controlling the temperature of a soaking section according to 1150 +/-40 ℃, controlling the initial rolling temperature to 1050 ℃, adopting a four-segmentation process and a pass system, controlling the rolling speed of a finished rack to be 13m/s, and controlling the temperature of a cooling bed to be 960 ℃;
4) Controlling steel making and rolling according to the process parameters, wherein the weight deviation of the two middle lines of the four-split steel bars is-2.4%, -2.1%, the yield strength is 455MPa and 450MPa, the weight deviation of the two lines of the four-split side steel bars is-5.2%, -5.0%, the yield strength is 445MPa and 450MPa, other tensile property indexes and weight deviation of the steel bars meet the requirements of GB/T1499.2-2018 standards, and the strength fluctuation of the split steel bars is within 10 MPa.
The niobium-added steel bar has four cutting performances:
the yield strength is 420-465 MPa, and the average value is 443MPa;
poor same batch property line (yield strength): 0 to 15MPa; the average value was 6MPa.
The niobium-added steel bar has three-cutting performance:
the yield strength is 425-465 MPa, and the average value is 448MPa;
poor same batch property line (yield strength): 0 to 10MPa; the average value was 4MPa.
Example 2
The method is applied to the phi 18mm and HRB400E steel bars produced by the willow steel according to the GB/T1499.2-2018 standard by adopting a three-segmentation process, and comprises the following specific steps:
1) Controlling smelting components of the blank: carbon: 0.23%, silicon: 0.46%, manganese: 1.44%, phosphorus: 0.026%, sulfur: 0.027%, vanadium: 0.026%, nitrogen: 0.0088%
2) Pre-cut holes K4 and cut holes K3 in the rolling process, and hole pattern design and manufacturing requirements of a front finished product hole K2 and a finished product hole K1 are as follows: the inner diameter of the three-cut middle hole is enlarged by 3 percent than that of the two side holes;
3) Heating the billet in the furnace for 62min by adopting three-stage heating, controlling the temperature of a soaking section according to 1150 +/-40 ℃, controlling the rolling temperature at 1060 ℃, adopting a three-segmentation process and a pass system, controlling the rolling speed of a finished rack at 13m/s, and controlling the temperature of a cooling bed at 980 ℃;
4) Controlling steel making and rolling according to the process parameters, wherein the weight deviation of the steel bar at the middle line of the three-segmentation is-1.8%, the yield strength is 455MPa, the weight deviation of the steel bar at the two lines at the side surfaces of the three-segmentation is-4.5%, -4.6%, the yield strength is 455MPa and 460MPa, other tensile property indexes and weight deviations of the steel bar meet the requirements of GB/T1499.2-2018 standard, and the strength fluctuation of the steel bar at each segmentation line is within 5MPa.
The vanadium (nitrogen) added steel bar has four cutting performances:
the yield strength is 420-475 MPa, and the average value is 456MPa;
poor same batch property line (yield strength): 0 to 15MPa; the average value was 5MPa.
The vanadium (nitrogen) added steel bar has three cutting performances:
the yield strength is 420-480 MPa, and the average value is 453MPa;
poor same batch property line (yield strength): 0 to 10MPa; the average value was 4MPa.
Further, the invention also provides a split steel bar with small performance line difference, and the split steel bar comprises the following components: carbon: 0.18% -0.25%, silicon: 0.20-0.80%, manganese: 1.20-1.60 percent of phosphorus, less than or equal to 0.0045 percent of phosphorus and less than or equal to 0.0045 percent of sulfur; niobium: 0.023% -0.033% or
Carbon: 0.18% -0.25%, silicon: 0.20-0.80%, manganese: 1.20-1.60 percent of phosphorus, less than or equal to 0.0045 percent of phosphorus and less than or equal to 0.0045 percent of sulfur; niobium: 0.023% -0.033% and vanadium: 0.022% -0.034%, nitrogen: 0.0080% -0.0110%;
after splitting, the weight deviation of the steel bars of the middle line is 2.5-3.5% larger than that of the steel bars of the two lines of the side surface.
Furthermore, the segmented steel bars with small performance line difference are four segmented steel bars, and after segmentation, the weight deviation of the steel bars on the two middle lines of the segmented steel bars on the segmented line is 2.5-3.5% larger than that of the steel bars on the two side lines of the segmented steel bars on the side surface.
Furthermore, the split steel bars with small performance line difference are three split steel bars, and after the split steel bars are split, the weight deviation of the steel bars in the middle line on the split line is 2.5-3.5% larger than that of the steel bars in the two lines on the side surface.
The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. In order that the components of the present invention may be combined without conflict, it should be apparent to one skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
Claims (9)
1. The production method for reducing the performance linear difference of the reinforcing steel bar is characterized by comprising the following steps of:
step A: controlling the components of the steel bar blank: carbon: 0.18% -0.25%, silicon: 0.20-0.80%, manganese: 1.20 to 1.60 percent, less than or equal to 0.045 percent of phosphorus and less than or equal to 0.045 percent of sulfur; rolling the steel bar by adopting a continuous casting square billet;
and B: rolling the reinforcing steel bars with the specification of phi 12-phi 20mm by adopting a three-slitting or four-slitting process, wherein the three-slitting or four-slitting process mainly comprises front cutting holes K5-K7, precutting holes K4, slitting holes K3, finished product front holes K2 and finished product holes K1, and the front cutting holes are elliptical holes, rectangular holes or box-shaped holes; precutting hole K4, segmentation hole K3, the pass of finished product front hole K2 and finished product hole K1 is:
the inner diameter of the middle hole of each hole type is 3 percent larger than that of the holes at the two sides of each hole type;
and C: heating the billet for rolling the reinforcing steel bar in a furnace for 60-90 min, adopting three-stage heating, controlling the temperature of a soaking section at 1150 +/-40 ℃, controlling the initial rolling temperature at 1040 +/-30 ℃, heating the billet, rolling the heated billet by a rough, medium and finish rolling tandem mill set, controlling the rolling speed of a finished product rack at 10-15 m/s, and controlling the temperature of an upper cooling bed to be more than or equal to 920 ℃;
the strength difference of each line of steel bars after cutting is reduced from 0-25 MPa to below 0-15 MPa.
2. The method for producing a reduced difference in performance line of reinforcing bars according to claim 1, wherein the two middle holes of the four-slit are enlarged by 3% of the inner diameter of the holes than the two side holes of the four-slit, so that the weight deviation of the two middle holes of the four-slit is 2.5-3.5% greater than that of the two side reinforcing bars under the condition of ensuring the normal control of the material type in the rolling process.
3. The method for producing a reduced line of performance of a reinforcing bar according to claim 1, wherein the three-slit center hole has a hole diameter larger than the three-slit side holes by 3%, so that the weight deviation of the three-slit center line is 2.5 to 3.5% larger than that of the two-line reinforcing bar on the side surface under the condition of ensuring the normal control of the material type in the rolling process.
4. The method for reducing the line difference of the performance of the steel bar according to claim 3, wherein in the step B, the steel billet is heated in the furnace for 65min by adopting three-stage heating, the temperature of a soaking stage is controlled according to 1150 +/-40 ℃, the rolling temperature is 1050 ℃, a four-slitting process and a hole pattern system are adopted, the rolling speed of a finished stand is controlled at 13m/s, and the temperature of a cooling bed is 960 ℃.
5. The method for producing a reduced line difference of performance of a steel bar according to claim 1, wherein in the step a, the ratio of carbon: 0.23%, silicon: 0.46%, manganese: 1.44%, phosphorus: 0.026%, sulfur: 0.027 percent.
6. The method for producing a steel bar with reduced line difference of performance according to claim 5, wherein in step B, the billet is heated in the furnace for 62min, three-stage heating is adopted, the temperature of the soaking section is controlled according to 1150 +/-40 ℃, the initial rolling temperature is 1060 ℃, a three-segment process and a pass system are adopted, the rolling speed of the finished stand is controlled at 13m/s, and the temperature of the upper cooling bed is 980 ℃.
7. The method for producing a steel bar with reduced line difference of performance according to claim 1, wherein in the step a, the steel bar stock further comprises niobium: 0.023% -0.033% or vanadium: 0.022% -0.034%, nitrogen: 0.0080% -0.0110%.
8. The method for producing a reduced line difference of performance of a steel bar according to claim 1, wherein in the step a, the ratio of carbon: 0.24%, silicon: 0.55%, manganese: 1.34%, phosphorus: 0.023%, sulfur: 0.028%, niobium: 0.025 percent.
9. The method for producing a reduced line difference of performance of a steel bar according to claim 1, wherein in the step a, the ratio of carbon: 0.23%, silicon: 0.46%, manganese: 1.44%, phosphorus: 0.026%, sulfur: 0.027%, vanadium: 0.026%, nitrogen: 0.0088%.
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| CN113600622B (en) * | 2021-07-23 | 2023-08-11 | 首钢水城钢铁（集团）有限责任公司 | Method for controlling size of finished product full bar through multi-line bar segmentation |
| CN114196876B (en) * | 2021-11-05 | 2022-06-24 | 柳州钢铁股份有限公司 | High-safety hot-rolled steel bar and production method thereof |
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