CN113278777A - Method for controlling steel strip-shaped structure of alloy structure - Google Patents
Method for controlling steel strip-shaped structure of alloy structure Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
- 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
- B22D11/18—Controlling or regulating processes or operations for pouring
- B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
- B22D11/182—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level by measuring temperature
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- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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Abstract
The invention relates to a method for controlling a steel strip structure of an alloy structure, which comprises the steps of controlling the superheat degree delta t of molten steel during casting according to the carbon content of alloy structure steel in the casting process, wherein the basic superheat degree range of the alloy structure steel is (A1-A2) DEG C, further reducing the superheat degree according to 10 times of the carbon content mass percent C of the alloy structure steel on the basis of the basic superheat degree, and the steel during castingDegree of superheat of water Deltat is in accordance with [ (A)1‑10*C)~(A2‑10*C)]Setting the temperature to be DEG C, wherein C is the mass percentage of the carbon content of the alloy structural steel; controlling the secondary cooling ratio water index of continuous casting billet cooling during casting according to the carbon content of the alloy structural steel in the casting process, wherein the secondary cooling ratio water index of continuous casting is [0.9+ 0.2C ]]L/kg, wherein C is the mass percent (%) of the carbon content; and a preheating section, a soaking section and a heating section are adopted to reheat the continuous casting billet, and the heating temperature and the heating time of each section are controlled and increased according to the specification of the product.
Description
Technical Field
The invention belongs to the technical field of iron-based alloy, and particularly relates to alloy structural steel.
Background
The alloy structural steel is mainly used as mechanical parts, automobile parts, engineering components and the like. Because of the action of alloy elements, the alloy structural steel has better mechanical properties, and the high-quality alloy structural steel is an important basis of modern industry.
The strip structure of the alloy structural steel can cause anisotropy of the steel, and the strength and toughness of the steel are reduced; the steel material is easy to deform after heat treatment, the cold bending performance is reduced, the stamping rejection rate is high, and other adverse effects can be caused, so that the production efficiency of industrial parts and the service life of products are influenced.
The alloy structural steel contains certain content of carbon elements and alloy elements, so that dendritic segregation is inevitably generated in the casting process of the carbon elements and the alloy elements, a pro-eutectoid ferrite strip and a pearlite strip are formed in the rolling process of the steel along the rolling direction of the steel, and the pro-eutectoid ferrite strip and the pearlite strip are stacked with each other to finally generate a banded structure. The control of the banded structure is always a difficult point in the field of metallurgical production, and the banded structure of the alloy structural steel hot rolled material of the advanced level in the world can be stably controlled to be less than or equal to 2.0 level at present.
The reason for the generation of the steel strip-shaped structure of the alloy structure is as follows: and the carbon element and the alloy element are partially aggregated to generate micro segregation in the continuous casting process. The segregated chemical elements generally lower the Ar3 temperature of the steel, thereby promoting the formation of a steel strip. During rolling, dendritic segregation in the billet is elongated in the rolling direction to form pro-eutectoid ferrite and pearlite bands in the rolling direction of the steel, which are stacked on each other to finally generate a band-shaped structure.
The existing research results show that: the technological parameters in the casting process of the casting blank and the casting blank heating process have great influence on dendritic segregation and interdendritic segregation formed by carbon elements and alloy elements, so that the final strip structure of the steel is determined. Determining reasonable continuous casting superheat degree and specific water index according to alloy structural steel with different carbon contents; according to the alloy structural steel with different carbon contents and the casting blanks with different specifications, reasonable heating temperature and heating time are set, and the steel strip-shaped structure of the alloy structure can be effectively controlled.
Patent CN 103194580 a discloses a rolling method of low-strip-shaped structure alloy structural steel, which reduces the strip-shaped structure of the alloy structural steel to a lower level through the procedures of billet heating, rough rolling, intermediate rolling, water cooling, finish rolling, water cooling, air cooling, shearing and slow cooling and proper process parameters.
Patent 200810223796.1 discloses a method for controlling the strip-shaped structure of structural alloy steel, which comprises the steps of molten iron pretreatment, converter-ladle refining, vacuum degassing, continuous casting of steel billets, heating of the steel billets, rolling of the steel billets by 20 continuous rolling mills, and controlling the hot rolled round steel produced at different finishing rolling temperatures to enable the grade of the strip-shaped structure of the structural alloy steel to be less than or equal to 2.5, thereby meeting the requirements of users.
The above patent technologies realize the control level of the banded structure through measures such as the temperature of the water cooling control process in the rolling process, cooling after rolling and the like, but the control process is complex, the operation difficulty is high, and the control effect of the banded structure is difficult to effectively ensure.
Disclosure of Invention
In order to solve the problem that the banded structure in the alloy structural steel is obvious, the invention aims to provide a brand-new production process method for controlling the continuous casting superheat degree, the secondary cooling specific water index, the casting blank heating temperature and the heating time, and the optimized new method can control the banded structure level in the alloy structural steel to be less than or equal to 2.0 level.
The technical scheme adopted by the invention for solving the problems is as follows: a method for controlling a strip structure of an alloy structural steel obtained by hot rolling a cast slab cast from molten steel, comprising
(1) Casting blank by adopting continuous casting process
(1.1) controlling the superheat degree delta t of molten steel during casting according to the carbon content of the alloy structural steel in the casting process, wherein the basic superheat degree range of the alloy structural steel is (A1-A2) DEG C, the superheat degree is further reduced according to 10 times of the carbon content mass percentage C of the alloy structural steel on the basis of the basic superheat degree, and the superheat degree delta t of the molten steel during casting is according to [ (A) the superheat degree delta t of the molten steel during casting1-10*C)~(A2-10*C)]Setting the temperature at the preset value, wherein C is the mass percentage of the carbon content of the alloy structural steel.
T-T superheat degree of continuous castingPouring basket-TMolten steelThe setting of the basic superheat degree of continuous casting firstly considers the production efficiency of a casting blank, and the condition that the temperature of a tundish is too low (close to or lower than the liquidus temperature of steel grade) can cause the 'death' of molten steel in a water port of a crystallizer; the tundish temperature is too high, and bleed-out may be caused. The two conditions reduce the billet production efficiency to a certain extent and reduce the billet yield. By continuously adjusting the superheat degree of the alloy structural steel, a large number of production tests and large data acquisition and analysis are carried out, the basic superheat degree range of the alloy structural steel is determined to be (A1-A2) DEG C, the superheat degree range can ensure the optimal production efficiency of the alloy structural steel, and the determined standard is the highest or higher superheat degree range which ensures that steel leakage does not occur in the continuous casting process. On the basis, the strip-shaped structure in the structural steel is further considered to be improved, the influence of different superheat degrees on the grade of the strip-shaped structure is inspected by adjusting the basic superheat degree range and carrying out large-scale production tests, and the optimal superheat degree adjusting variable is found to be-10C when the molten steel of the alloy structural steel is cast, C is the mass percent (%) of C element in the alloy structural steel, namely the optimal range of the continuous casting superheat degree is [ (A)1-10*C)~(A2-10*C)]The alloy structural steel produced according to the superheat degree range can achieve the optimal composition segregation and banded structure, and the casting blank yield is relatively high.
(1.2) controlling a secondary cooling ratio water index of continuous casting billet cooling during casting according to the carbon content of the alloy structural steel in the casting process, wherein the secondary cooling ratio water index of continuous casting is set according to [0.9+ 0.2C ] L/kg, and C is the mass percent (%) of the carbon content.
The secondary cooling ratio water index is the ratio n of the total water consumed in the secondary cooling area of the continuous casting machine in unit time to the mass of a casting blank passing through the secondary cooling area in unit time, wherein n is a constant of 1.15 and is expressed in L/kg. The basic specific water index of the alloy structural steel is obtained by continuously adjusting the continuous casting specific water index, the alloy structural steel can obtain the optimal surface quality by setting the basic specific water index, namely, the surface of the continuous casting billet is flat, smooth and free of defects, and generally, for the basic alloy structural steel, the basic specific water index is 0.90L/kg, so that the production can be met. In order to reduce segregation of the slab and the band structure of the steel, it is necessary to increase the base specific water content index. And obtaining the variable + 0.2C of the specific water index of the alloy structural steel through a large-scale process test of specific water index adjustment and corresponding large data acquisition and analysis. That is, the specific water index should be set to (0.90+0.2 × C) L/kg. The alloy structural steel produced according to the water ratio index has the best composition segregation and banded structure, and the surface quality of the casting blank is also better.
(2) Reheating a continuous cast slab before rolling the slab
Adopting preheating section, soaking section, heating section to reheat the continuous casting billet, the heating temperature and the heating time of each section set up the reference:
(2.1) for a billet continuous casting billet, a preheating section: heating at the temperature of (650-800) + 50C DEG C for (h 0.20+10) - (h 0.45+10) min; a soaking section: heating at the temperature of (1000-1150) + 100C DEG C for (h 0.25+10) - (h 0.50+10) min; a heating section: heating temperature [ (1100-1250) +100 × C ] DEG C, heating time [ (h × 0.25+10) - (h × 0.60+10) ] min.
(2.2) for a round billet continuous casting blank, a preheating section: heating at 650-800 + 50C deg.C for [ d 0.25+20) - (d 0.50+20) ] min; a soaking section: heating at the temperature of (1000-1150) + 100C DEG C for (d 0.30+20) - (d 0.55+20) min; a heating section: heating temperature [ (1100-1250) +100 × C ] ° C, heating time [ (d × 0.30+20) - (d × 0.65+20) ] min.
In the formula, C is the mass percent (%) of the carbon content of the alloy structural steel; d is the diameter (mm) of the continuous casting round billet; h is the thickness (mm) of the continuous casting square billet.
The setting of the basic heating temperature of the three-section heating process of steel rolling takes energy conservation into priority, a large number of tests prove that the setting of the basic heating temperature can save energy as much as possible on the premise of meeting production, and the basic heating temperature interval is set according to the principle that the plasticity in the steel rolling process can be ensured, so that blanks with excellent heating quality are provided for the rolling mill, and the service life of the rolling mill is ensured. In order to reduce segregation of the slab and the band structure of the steel, the heating temperature of the rolled steel may be appropriately increased. And the optimal rolling temperature variable is obtained through large-scale process experiment groping. The steel rolling three-section heating temperature is properly adjusted according to different carbon contents, and the environment protection and energy conservation are considered while the steel segregation and the banded structure are improved.
Further, the chemical composition (100% by mass) of the alloy structural steel suitable for the above-described control method satisfies C: 0.08-0.60%, Si: 0.17-1.40%, Mn: 0.30 to 2.60 percent of Cr, 0.10 to 1.65 percent of Cr, less than or equal to 0.55 percent of Mo, less than or equal to 4.50 percent of Ni, less than or equal to 0.20 percent of Cu, less than or equal to 0.50 percent of V, less than or equal to 0.10 percent of Ti, less than or equal to 1.10 percent of Al, less than or equal to 0.0035 percent of B, and less than or equal to 1.20 percent of W. The basic superheat degree range (A1-A2) DEG C of molten steel based on the chemical components is (35-55) ° C through field tests.
Compared with the prior art, the invention has the advantages that: the invention adjusts the continuous casting superheat degree and the secondary cooling ratio water quantity index according to different carbon contents of the alloy structural steel. The heating temperature and the heating time of the alloy structural steel with different carbon contents and the casting blanks with different specifications are adjusted, so that the improvement of the banded structure of the alloy structural steel is facilitated, and the grade of the banded structure is reduced to be below 2.0. The invention has the characteristics of simple and convenient production operation, easy realization of control and the like.
Detailed Description
The present invention is described in further detail below in connection with the following examples, which are intended to be illustrative and not to be construed as limiting the invention.
Example 1:
the production process comprises the following steps: 100tEAF + LF + VD + CCM (300mm multiplied by 340mm) casting blank-continuous casting square blank heating-continuous casting square blank rolling to phi 55 mm.
Continuous casting: the superheat degree of the tundish is 34 ℃, and the secondary cooling specific water index is 0.94L/kg.
The heating process of the continuous casting square billet in a heating furnace comprises the following steps: the temperature of the preheating section is 699 ℃, and the time is 89 minutes; the temperature of the heating section is 1042 ℃ for 101 minutes, and the temperature of the soaking section is 1145 ℃ for 102 minutes.
The steel produced in this example had the main chemical components of C0.20%, Si 0.23%, Mn 0.65%, Cr 0.82%, P0.015%, and S0.002%. The rolled steel has a banded structure grade of 1.5.
Comparative example 1:
the production process comprises the following steps: 100tEAF + LF + VD + CCM (300mm multiplied by 340mm) casting blank-continuous casting square blank heating-continuous casting square blank rolling to phi 55 mm.
Continuous casting: the superheat degree of the tundish is 54 ℃, and the secondary cooling specific water index is 0.91L/kg.
The heating process of the continuous casting square billet in a heating furnace comprises the following steps: the temperature of the preheating section is 653 ℃ and the time is 74 minutes; the temperature of the heating section is 1008 ℃ and the time is 93 minutes, and the temperature of the soaking section is 1112 ℃ and the time is 91 minutes.
The steel produced in this example had the main chemical components of C0.20%, Si 0.25%, Mn 0.66%, Cr 0.81%, P0.013%, and S0.002%. The rolled steel has a banded structure grade of 3.0.
Example 2:
the production process comprises the following steps: 100tEAF + LF + VD + CCM (300mm multiplied by 340mm) casting blank-continuous casting square blank heating-continuous casting square blank rolling to phi 65 mm.
Continuous casting: the superheat degree of the tundish is 36 ℃, and the secondary cooling specific water index is 0.96L/kg.
The heating process of the continuous casting square billet in a heating furnace comprises the following steps: the temperature of the preheating section is 706 ℃, and the time is 86 minutes; the temperature of the heating section is 1061 ℃ and the time is 101 minutes, and the temperature of the soaking section is 1163 ℃ and the time is 102 minutes.
The steel produced in the embodiment comprises 0.30% of C, 0.27% of Si, 1.56% of Mn, 0.017% of P and 0.003% of S. The rolled steel has a banded structure grade of 1.0.
Comparative example 2:
the production process comprises the following steps: 100tEAF + LF + VD + CCM (300mm multiplied by 340mm) casting blank-continuous casting square blank heating-continuous casting square blank rolling to phi 65 mm.
Continuous casting: the superheat degree of the tundish is 31 ℃, and the secondary cooling specific water index is 0.96L/kg.
The heating process of the continuous casting square billet in a heating furnace comprises the following steps: the temperature of the preheating section is 652 ℃, and the time is 73 minutes; the temperature of the heating section is 1021 ℃ for 91 minutes, and the temperature of the soaking section is 1120 ℃ for 89 minutes.
The steel grade produced in the embodiment comprises 0.30% of C, 0.29% of Si, 1.55% of Mn, 0.016% of P and 0.002% of S. The rolled steel has a banded structure grade of 2.5.
Example 3:
the production process comprises the following steps: 100tEAF + LF + VD + CCM (300mm multiplied by 340mm) casting blank-continuous casting square blank heating-continuous casting square blank rolling to phi 80 mm.
Continuous casting: the superheat degree of the tundish is 32 ℃, and the secondary cooling specific water index is 0.97L/kg.
The heating process of the continuous casting square billet in a heating furnace comprises the following steps: the temperature of the preheating section is 709 ℃ and the time is 89 minutes; the temperature of the heating section is 1067 ℃ for 100 minutes, and the temperature of the soaking section is 1162 ℃ for 105 minutes.
The steel grade produced in the example comprises 0.35% of C, 0.26% of Si, 0.56% of Mn, 0.96% of Cr, 0.19% of Mo, 0.013% of P and 0.002% of S. The rolled steel has a banded structure grade of 1.5.
Comparative example 3:
the production process comprises the following steps: 100tEAF + LF + VD + CCM (300mm multiplied by 340mm) casting blank-continuous casting square blank heating-continuous casting square blank rolling to phi 80 mm.
Continuous casting: the superheat degree of the tundish is 53 ℃, and the secondary cooling specific water index is 0.93L/kg.
The heating process of the continuous casting square billet in a heating furnace comprises the following steps: the temperature of the preheating section is 661 ℃ and the time is 79 minutes; the temperature of the heating section is 1029 ℃ and the time is 93 minutes, and the temperature of the soaking section is 1122 ℃ and the time is 92 minutes.
The steel grade produced in the example comprises 0.35% of C, 0.25% of Si, 0.55% of Mn, 0.012% of P, 0.19% of Mo, 0.012% of P and 0.002% of S. The rolled steel has a banded structure grade of 2.5.
Example 4:
the production process comprises the following steps: 100tEAF + LF + VD + CCM (300mm multiplied by 340mm) casting blank-continuous casting square blank heating-continuous casting square blank rolling to phi 70 mm.
Continuous casting: the superheat degree of the tundish is 31 ℃, and the secondary cooling specific water index is 1.00L/kg.
The heating process of the continuous casting square billet in a heating furnace comprises the following steps: the temperature of the preheating section is 719 ℃, and the time is 89 minutes; the temperature of the heating section is 1083 ℃ for 102 minutes, and the temperature of the soaking section is 1185 ℃ for 103 minutes.
The steel grade produced in the example comprises the following main chemical components of 0.50% of C, 0.26% of Si, 0.59% of Mn, 0.67% of Cr, and Ni: 1.25 percent, P is 0.012 percent and S is 0.003 percent. The rolled steel has a banded structure grade of 1.5.
Comparative example 4:
the production process comprises the following steps: 100tEAF + LF + VD + CCM (300mm multiplied by 340mm) casting blank-continuous casting square blank heating-continuous casting square blank rolling to phi 70 mm.
Continuous casting: the superheat degree of the tundish is 52 ℃, and the secondary cooling specific water index is 0.92L/kg.
The heating process of the continuous casting square billet in a heating furnace comprises the following steps: the temperature of a preheating section is 672 ℃, and the time is 77 minutes; the temperature of the heating section is 1041 ℃ for 93 minutes, and the temperature of the soaking section is 1142 ℃ for 92 minutes.
The steel grade produced in the example comprises the following main chemical components of 0.50% of C, 0.25% of Si, 0.58% of Mn, 0.69% of Cr, and Ni: 1.25 percent, P0.013 percent and S0.003 percent. The rolled steel has a banded structure grade of 3.0.
Example 5:
the production process comprises the following steps: 100tBOF + LF + RH + CCM (phi 600mm), casting blank, continuous casting round blank heating and continuous casting square blank rolling into phi 120 mm.
Continuous casting: the superheat degree of the tundish is 36 ℃, and the secondary cooling specific water index is 0.94L/kg.
The heating process of the continuous casting round billet in a heating furnace comprises the following steps: the temperature of the preheating section is 701 ℃ and the time is 189 minutes; the temperature of the heating section is 1056 ℃, and the time is 221 minutes; the temperature of the soaking section is 1159 ℃, and the time is 237 minutes.
The steel for the high-grade automobile produced in the embodiment comprises the following main chemical components of 0.20% of C, 0.22% of Si, 1.16% of Mn, 1.17% of Cr, 0.012% of P and 0.002% of S. The rolled steel has a banded structure grade of 0.5.
Comparative example 5:
the production process comprises the following steps: 100tBOF + LF + RH + CCM (phi 600mm), casting blank, continuous casting round blank heating and continuous casting square blank rolling into phi 120 mm.
Continuous casting: the superheat degree of the tundish is 27 ℃, and the secondary cooling specific water index is 0.91L/kg.
The heating process of the continuous casting round billet in a heating furnace comprises the following steps: the temperature of the preheating section is 656 ℃, and the time is 166 minutes; the temperature of the heating section is 1009 ℃, and the time is 191 minutes; the temperature of the soaking section is 1112 ℃, and the time is 201 minutes.
The steel for the high-grade automobile produced in the embodiment comprises the main chemical components of 0.20% of C, 0.23% of Si, 1.15% of Mn, 1.17% of Cr, 0.011% of P and 0.002% of S. The rolled steel has a banded structure grade of 2.5.
Example 6:
the production process comprises the following steps: 100tBOF + LF + RH + CCM (phi 600mm), casting blank-continuous casting round blank heating-continuous casting square blank rolling to phi 110 mm.
Continuous casting: the superheat degree of the tundish is 45 ℃, and the secondary cooling specific water index is 0.98L/kg.
The heating process of the continuous casting round billet in a heating furnace comprises the following steps: the temperature of the preheating section is 713 ℃ and the time is 189 minutes; the temperature of the heating section is 1073 ℃, and the time is 219 minutes; the temperature of the soaking section is 1179 ℃, and the time is 237 minutes.
The steel for the high-grade automobile produced in the embodiment comprises the following main chemical components of 0.40% of C, 0.23% of Si, 0.69% of Mn, 1.08% of Cr, 0.21% of Mo, 0.012% of P and 0.002% of S. The rolled steel has a banded structure grade of 0.5.
Comparative example 6:
the production process comprises the following steps: 100tBOF + LF + RH + CCM (phi 600mm), casting blank-continuous casting round blank heating-continuous casting square blank rolling to phi 110 mm.
Continuous casting: the superheat degree of the tundish is 29 ℃, and the secondary cooling specific water index is 0.92L/kg.
The heating process of the continuous casting round billet in a heating furnace comprises the following steps: the temperature of the preheating section is 665 ℃, and the time is 165 minutes; the temperature of the heating section is 1035 ℃, and the time is 196 minutes; the soaking section temperature is 1135 ℃, and the time is 193 minutes.
The steel for the high-grade automobile produced in the embodiment comprises 0.40% of C, 0.26% of Si, 0.68% of Mn, 1.09% of Cr, 0.21% of Mo, 0.011% of P and 0.002% of S. The rolled steel has a banded structure grade of 2.5.
In addition to the above embodiments, the present invention also includes other embodiments, and any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of the claims of the present invention.
Claims (3)
1. A method for controlling a steel strip structure of an alloy structural steel obtained by hot rolling a cast slab cast from molten steel, characterized by comprising: the method for controlling the banded tissue includes
(1) Casting blank by adopting continuous casting process
(1.1) controlling the superheat degree delta t of molten steel during casting according to the carbon content of the alloy structural steel in the casting process, wherein the basic superheat degree range of the alloy structural steel is (A1-A2) DEG C, the superheat degree is further reduced according to 10 times of the carbon content mass percentage C of the alloy structural steel on the basis of the basic superheat degree, and the superheat degree delta t of the molten steel during casting is according to [ (A) the superheat degree delta t of the molten steel during casting1-10*C)~(A2-10*C)]Setting the temperature to be DEG C, wherein C is the mass percentage of the carbon content of the alloy structural steel;
(1.2) controlling a secondary cooling ratio water index of continuous casting billet cooling during casting according to the carbon content of the alloy structural steel in the casting process, wherein the secondary cooling ratio water index of continuous casting is set according to [0.9+ 0.2C ] L/kg, and C is the mass percent (%) of the carbon content;
(2) reheating a continuous cast slab before rolling the slab
Adopt preheating section, soaking section, heating section to the continuous casting billet reheat, the heating temperature of each section and the specification control of heating time reference product refer to:
(2.1) for a billet continuous casting billet, a preheating section: heating at the temperature of (650-800) + 50C DEG C for (h 0.20+10) - (h 0.45+10) min; a soaking section: heating at the temperature of (1000-1150) + 100C DEG C for (h 0.25+10) - (h 0.50+10) min; a heating section: heating temperature [ (1100-1250) +100 × C ] ° C, heating time [ (h × 0.25+10) - (h × 0.60+10) ] min;
(2.2) for a round billet continuous casting blank, a preheating section: heating at 650-800 + 50C deg.C for [ d 0.25+20) - (d 0.50+20) ] min; a soaking section: heating at the temperature of (1000-1150) + 100C DEG C for (d 0.30+20) - (d 0.55+20) min; a heating section: heating at the temperature of (1100-1250) + 100C DEG C for (d 0.30+20) - (d 0.65+20) min;
in the formula, C is the mass percent (%) of the carbon content of the alloy structural steel; d is the diameter (mm) of the continuous casting round billet; h is the thickness (mm) of the continuous casting square billet.
2. The method of controlling the strip-like structure of an alloy structural steel according to claim 1, characterized in that: the alloy structural steel comprises the following chemical components in percentage by weight: 0.08-0.60%, Si: 0.17-1.40%, Mn: 0.30 to 2.60 percent of Cr, 0.10 to 1.65 percent of Cr, less than or equal to 0.55 percent of Mo, less than or equal to 4.50 percent of Ni, less than or equal to 0.20 percent of Cu, less than or equal to 0.50 percent of V, less than or equal to 0.10 percent of Ti, less than or equal to 1.10 percent of Al, less than or equal to 0.0035 percent of B, and less than or equal to 1.20 percent of W.
3. The method of controlling the strip-like structure of an alloy structural steel according to claim 2, characterized in that: in the step (1), the basic superheat range (A1-A2) DEG C is (35-55) DEG C based on the alloy structural steel of the above element components.
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