CN115216683A - Method for regulating and controlling ferrite form in casting blank tissue and prepared microalloyed steel - Google Patents
Method for regulating and controlling ferrite form in casting blank tissue and prepared microalloyed steel Download PDFInfo
- Publication number
- CN115216683A CN115216683A CN202210547101.5A CN202210547101A CN115216683A CN 115216683 A CN115216683 A CN 115216683A CN 202210547101 A CN202210547101 A CN 202210547101A CN 115216683 A CN115216683 A CN 115216683A
- Authority
- CN
- China
- Prior art keywords
- steel
- percent
- rare earth
- ferrite
- refining
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
-
- 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
-
- 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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
-
- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
-
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
-
- 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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a method for regulating and controlling ferrite form in a casting blank tissue and prepared microalloyed steel, belonging to the field of steel materials and metallurgical manufacturing. The production method comprises the working procedures of molten iron pretreatment, converter smelting, external refining and continuous casting. Specifically, boron alloy is added in the LF refining process, rare earth Ce alloy is added in the RH refining process, the B content and the rare earth Ce content in steel are reasonably controlled, and the temperature of a casting blank is controlled by cooling water in the continuous casting process. According to the invention, through the synergistic effect of boron, rare earth and cooling control in the continuous casting process, the addition amount of alloy elements is reduced, ferrite is regulated and controlled to be separated out in an intragranular ferrite form, the intragranular ferrite content is increased, the reduction of area of the casting blank is more than 70% through a Gleeble1500 thermal simulator, and the surface quality of the casting blank can be effectively improved.
Description
Technical Field
The invention belongs to the field of steel materials and metallurgical manufacturing, and particularly relates to a method for regulating and controlling ferrite morphology in a casting blank tissue and microalloyed steel prepared by the method, which are suitable for improving the surface quality of a casting blank in the continuous casting process of the microalloyed steel.
Background
With the development of industry and society, the performance requirements for steel materials are increasing day by day. Trace amounts of Nb, V, ti and other alloy elements are added into steel at present, the micro alloy elements can be combined with C and N in the steel to generate carbonitride, the carbonitride can prevent austenite grains from growing, and fine dispersed carbonitride can also play a role in strengthening a second phase, so that steel with high strength, high toughness and excellent welding performance is obtained, and the steel is widely applied to the fields of engineering machinery, railway vehicles, bridge buildings, pressure vessels and the like.
However, during continuous casting, the grain boundary is pinned by the fine carbonitrides in the microalloy steel, and the solid-dissolved Nb atoms have strong dragging action on the grain boundary and dislocation, so that the generation of dynamic recrystallization is inhibited, and meanwhile, a large amount of net-shaped intergranular ferrite is easily generated, and the strength of the grain boundary is reduced. When a microalloy steel casting blank passes through a straightening section in continuous casting, the lower-strength intergranular ferrite can form microcracks under the action of straightening stress, and the microcracks expand into macrocracks along grain boundaries, finally resulting in the formation of cracks on the surface of the casting blank, especially transverse corner cracks. The prior art can not eliminate the generation of transverse cracks at the corner of a casting blank, and can only reduce the influence by continuous casting corner cutting and rolling edge cutting, thereby reducing the yield of steel. Therefore, in order to fundamentally solve the surface quality problem of microalloyed steel in the continuous casting process, it is necessary to improve the ferrite morphology in the cast slab structure to inhibit the formation of ferrite along the crystal, and to develop a new method for regulating the ferrite morphology in the cast slab structure.
Disclosure of Invention
In order to solve the problems, the invention provides a method for regulating and controlling ferrite morphology in a casting blank structure and a prepared microalloyed steel. Through the synergistic effect of boron and rare earth, solid solution boron and solid solution rare earth with certain content exist in the steel, and meanwhile, rare earth inclusions and boride are generated, so that the segregation of S and P at the grain boundary is reduced, the occurrence of dynamic recrystallization is facilitated, and the ferrite is promoted to be separated out in an intragranular ferrite form; meanwhile, the cooling control in the continuous casting process is matched, the content of intragranular ferrite in the structure is further improved, the surface quality of the final casting blank is improved, and the yield of steel is obviously improved.
According to a first aspect of the invention, a method for regulating and controlling the ferrite morphology in a casting blank structure is provided, the method comprises molten iron pretreatment, converter smelting, LF refining, RH refining and continuous casting, boron alloy is added in the LF refining process, rare earth Ce alloy is added in the RH refining process, and the temperature of a casting blank is controlled by cooling water in the continuous casting process.
Furthermore, 25-35 t of scrap steel is added in the smelting process of the converter, the sulfur content in the scrap steel is less than or equal to 0.025 percent, and the proportion of molten iron entering the converter is controlled to be 80-90 percent; deoxidizing and alloying, and controlling the oxygen content of the steel to be less than or equal to 0.050 percent.
Preferably, 32t of scrap steel is added in the converter smelting process, the sulfur content in the scrap steel is 0.015 percent, and the proportion of molten iron fed into the converter is controlled at 85 percent.
The sulfur content in the scrap steel and the oxygen content of the converter tapping are controlled to be lower, so that the burden of deoxidation and desulfurization in the refining process can be reduced, and the improvement of the yield and the solid solution amount of the subsequent B and Ce is guaranteed.
Further, boron alloy is added in the LF refining process, aluminum alloy deoxidation and titanium alloy nitrogen fixation are sequentially added before the boron alloy is added, the temperature of the molten steel is more than 1580 ℃, and the total amount of B in the molten steel is 0.0010-0.0020% after the LF refining is finished.
Preferably, the temperature of the molten steel is 1610 ℃, and the total amount of B in the molten steel is 0.0016 percent after LF refining.
Further, the boron alloy includes, but is not limited to, ferroboron with 16.4% by mass of boron; the aluminum alloy comprises, but is not limited to, 38.9 mass percent aluminum iron; the titanium alloy comprises, but is not limited to, ferrotitanium with the mass percentage of titanium of 25.6%.
Furthermore, rare earth Ce alloy is added in the RH refining process, the vacuum degree is 0.20kPa, the vacuum treatment time is more than 15min, the oxygen content in the molten steel is controlled to be less than or equal to 0.0020 percent, the nitrogen content is controlled to be less than or equal to 0.0030 percent, and the total amount of the rare earth Ce in the molten steel is 0.025-0.050 percent after the RH refining is finished.
Preferably, the vacuum treatment time is 20min, the oxygen content in the molten steel is controlled to be 0.0015%, the nitrogen content is controlled to be 0.0025%, and the total content of rare earth Ce in the molten steel is controlled to be 0.030% after RH refining is finished.
Further, the rare earth Ce alloy comprises, but is not limited to, cerium iron, wherein the mass percent of Ce in the cerium iron is 20.0%, and the total mass percent of the rest impurity elements of carbon, sulfur, oxygen, phosphorus and the like is less than 0.02%.
Further, the surface temperature of the casting blank in the secondary cooling zone is controlled to be 630-920 ℃ in the continuous casting process, and the surface temperature of the casting blank in the straightening zone is controlled to be higher than 1050 ℃.
Preferably, the surface temperature of the cast slab in the secondary cooling zone is controlled to be 700 ℃ in the continuous casting process, and the surface temperature of the cast slab in the straightening zone is controlled to be 1100 ℃.
In the secondary cooling area of the casting machine, the temperature of the casting blank is controlled in the formation area of the intragranular ferrite, the intragranular ferrite content in the structure before the casting blank enters the straightening area is increased, and the intragranular ferrite with good ductility and toughness can reduce stress concentration caused by straightening stress.
Further, the continuous casting process adopts a secondary cooling nozzle for gas-water atomization. The nozzle mixes the compressed air and the water, so that the water drop penetration capacity is strong, and the cooling efficiency is high; meanwhile, the coverage area of the nozzle is wide, the casting blank is uniformly cooled, the surface temperature is accurately controlled, and the fluctuation range is 40-100 ℃.
According to a second aspect of the invention, the microalloyed steel is smelted according to the method for regulating and controlling the ferrite form in the casting blank structure, and the microalloyed steel comprises the following chemical components in percentage by mass: 0.10 to 0.14%, si:0.20 to 0.35%, mn:1.4 to 1.7%, nb:0.04 to 0.07%, V: 0.06-0.08%, al:0.010 to 0.040%, ti: 0.010-0.030%, N:0.0015 to 0.0030 percent, less than or equal to 0.0020 percent of O, less than or equal to 0.0060 percent of S, and the balance of iron and inevitable impurity elements, wherein the content of B is 0.0010 to 0.0015 percent, and the content of rare earth Ce is 0.020 to 0.050 percent.
Further, the steel casting blank mainly contains spherical or ellipsoidal Ce 2 O 2 S rare earth inclusions, wherein the number of the rare earth inclusions is 300/mm 2 And more than 85% of rare earth inclusions are smaller than 2 mu m in size.
Preferably, the number of the rare earth inclusions is 350/mm 2 And more than 85% of rare earth inclusions are smaller than 1 μm in size.
The linear expansion coefficient of the fine and evenly distributed rare earth inclusions is close to that of a steel matrix, and stress concentration is not easy to generate when the stress is applied; at the same time, rare earth inclusions Ce 2 O 2 S may provide a nucleation core for the generation of intragranular ferrite, thereby promoting the formation of intragranular ferrite.
Furthermore, the steel casting blank has no intergranular ferrite in a structure near a tensile fracture at the temperature of 650-1050 ℃, the ferrite is precipitated in the form of intragranular ferrite, and the intragranular ferrite accounts for more than 40%.
Preferably, the intragranular ferrite accounts for 45%.
Furthermore, no surface crack defect is found in the steel casting blank detection, and the reduction of area of the casting blank within the range of 650-1050 ℃ is measured to be more than 70%.
The invention has the beneficial effects that:
aiming at microalloy steel, the invention carries out boron and rare earth composite treatment in the external refining process, reasonably controls the boron content and the rare earth content in molten steel, controls the temperature of a casting blank by cooling water in the continuous casting process, and effectively regulates and controls the ferrite form in a casting blank tissue. The core of the method of the invention is that: by solid solution in steelThe characteristic that boron and rare earth are easy to be segregated at the grain boundary reduces the energy of the grain boundary and simultaneously reduces the dragging effect of solid-solution Nb atoms on the grain boundary and dislocation, thereby playing the roles of purifying the grain boundary and promoting dynamic recrystallization and inhibiting the formation of ferrite along the grain; the rare earth Ce can modify coarse inclusions in steel into fine and dispersed Ce 2 O 2 S rare earth inclusions, the linear expansion coefficients of which are close to that of a steel matrix, are not easy to generate stress concentration, and are coordinated with the matrix during deformation; produced rare earth inclusions and Fe 23 (C,B) 6 Borides can be used as nucleation cores of intragranular ferrite, so that the generation amount of the intragranular ferrite is increased; the temperature of the casting blank is controlled to be in the formation interval of the intragranular ferrite by utilizing the cooling water, the content of the intragranular ferrite in the structure is further improved, and the condition that the ferrite in the casting blank is precipitated in the form of the intragranular ferrite with better ductility and toughness is finally regulated, wherein the intragranular ferrite accounts for more than 40 percent. The casting blank smelted according to the invention has no surface crack defect by off-line detection, and the reduction of area of the casting blank is obviously higher than 70% within the range of 650-1050 ℃.
Drawings
FIG. 1 shows typical inclusion Ce in a cast slab according to an embodiment of the present invention 2 O 2 S。
FIG. 2 shows typical Al inclusions in an ingot blank according to a comparative example of the present invention 2 O 3 -MnS。
Figure 3 shows a microstructure near a 750 ℃ tensile fracture according to one embodiment of the invention.
FIG. 4 shows the microstructure in the vicinity of 750 ℃ tensile fracture according to one comparative example of the invention.
Figure 5 illustrates a microstructure near a 650 ℃ tensile fracture according to one embodiment of the invention.
The specific implementation mode is as follows:
in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail by examples below.
According to the technical scheme, a proper amount of B and Ce is added in the external refining process, and the temperature of a casting blank is controlled by cooling water in the continuous casting process, so that the form of ferrite in a casting blank structure is effectively regulated and controlled. The method sequentially comprises the steps of molten iron pretreatment, converter smelting, external refining and continuous casting. According to the invention, by controlling the boron content of the casting blank to be 0.0010-0.0015% and the rare earth content to be 0.020-0.050%, the synergistic effect of boron and rare earth is exerted, so that the steel contains a certain content of solid-solution boron and solid-solution rare earth, rare earth inclusions and boride are generated at the same time, segregation of S and P at a crystal boundary is reduced, dynamic recrystallization is facilitated, and thus ferrite is promoted to be precipitated in an intragranular ferrite form; meanwhile, the cooling control in the continuous casting process is matched, the content of intragranular ferrite in the structure is improved, the surface quality problem of a casting blank in the continuous casting process is solved, and the yield of steel products is greatly improved. The reason is that boron and rare earth dissolved in steel act to suppress the formation along the intragranular ferrite, the rare earth inclusions and boride increase the amount of intragranular ferrite generated, and the control of the casting slab temperature in the intragranular ferrite formation region promotes the formation of intragranular ferrite.
Examples
The production method of the microalloy steel comprises the working procedures of molten iron pretreatment, converter smelting, LF refining, RH refining and continuous casting, and comprises the following specific process steps:
(1) The molten iron is subjected to deep desulfurization through pretreatment.
(2) In the converter smelting process, molten iron and scrap steel are loaded into a 210t converter for smelting, wherein the adding amount of the scrap steel is 25-35 t, the sulfur content in the scrap steel is less than or equal to 0.025%, and the proportion of the molten iron fed into the converter is controlled to be 80-90%. Adding silicomanganese and ferromanganese for deoxidation and alloying, and controlling the oxygen content of the steel tapping to be less than or equal to 0.050%.
(3) Adding boron alloy in the LF refining process, and sequentially adding aluminum alloy and titanium alloy before adding the boron alloy, wherein the temperature of the molten steel is more than 1580 ℃, and the total amount of B in the molten steel is 0.0010-0.0020% after the LF refining is finished.
(4) Adding rare earth Ce alloy in the RH refining process, controlling the temperature of molten steel arriving at a station to be 1590-1600 ℃, the vacuum degree to be 0.20kPa, the vacuum treatment time to be more than 15min, controlling the oxygen content in the molten steel to be less than or equal to 0.0020 percent, controlling the nitrogen content to be less than or equal to 0.0030 percent, and controlling the total amount of the rare earth Ce in the molten steel to be 0.025-0.050 percent after the RH refining is finished.
(5) In the continuous casting process, a secondary cooling nozzle of gas-water atomization is adopted to adjust the temperature of a casting blank, the surface temperature of the casting blank in a secondary cooling zone is controlled to be 630-920 ℃, the surface temperature of the casting blank in a straightening zone is controlled to be higher than 1050 ℃, and a continuous casting plate blank with the thickness of 250mm is prepared.
The micro-alloy steel prepared by smelting comprises the following chemical components in percentage by mass: 0.10 to 0.14%, si:0.20 to 0.35%, mn:1.4 to 1.7%, nb:0.04 to 0.07%, V: 0.06-0.08%, al:0.010 to 0.040%, ti:0.010 to 0.030%, N:0.0015 to 0.0030 percent, less than or equal to 0.0020 percent of O, less than or equal to 0.0060 percent of S, and the balance of iron and inevitable impurity elements, wherein the content of B is 0.0010 to 0.0015 percent, and the content of rare earth Ce is 0.020 to 0.050 percent.
The chemical compositions and mass percentages of three specific examples and a comparative example of the invention are shown in table 1.
TABLE 1 chemical composition (wt%) of examples and comparative examples
Typical inclusions in cast slabs according to one embodiment of the present invention are shown in fig. 1, and typical inclusions in cast slabs according to one comparative example of the present invention are shown in fig. 2. By adopting the method of the invention, the inclusions in the microalloyed steel consist of coarse Al with edges and corners 2 O 3 Modification of-MnS composite inclusions into small-size ellipsoidal Ce 2 O 2 S rare earth inclusions.
The examples and comparative examples of the present invention were subjected to high temperature hot stretch testing by a Gleeble1500 thermal simulator. The specific process is as follows: 1) Sampling at the 1/4 thickness part of a casting blank, and processing into a high-temperature hot tensile sample with phi 10mm multiplied by 120mm and two threaded ends; 2) The high-temperature hot tensile test is carried out under the protection of argon, the sample is heated to 1250 ℃ at the heating speed of 10 ℃/s, the temperature is kept for 3min to eliminate the temperature gradient and make the components uniform, then the sample is cooled to the tensile temperature (650 ℃ -1050 ℃ and 50 ℃ interval) at the cooling rate of 3 ℃/s, the temperature is kept for 30s, and then the sample is heated to the temperature of 1 multiplied by 10 -3 Breaking the sample at a deformation rate of/s, and spraying water to the fracture immediately after breakingCooling to room temperature; 3) The reduction of area of each sample was calculated and the microstructure near the fracture was analyzed.
Generally, it is considered that the reduction of area is less than 60%, the crack sensitivity of the cast slab is significantly improved, and crack defects are easily generated. The reduction of area at different drawing temperatures for the examples and comparative examples of the present invention are shown in Table 2.
TABLE 2 area reduction (%)
As can be seen from the data in Table 2, the reduction of area for each drawing temperature is higher for the examples than for the comparative examples. Specifically, the reduction of area in examples 1 to 3 is higher than 70% in the range of 650 to 1050 ℃; in contrast, in comparative example 1, the reduction of area is less than 60% in the temperature range of 700-850 ℃, and only 37.43% in the temperature range of 750 ℃, so that corner transverse cracks are easily formed when the casting blank passes through the straightening area of the continuous casting machine, and the surface quality is poor.
The microstructure in the vicinity of 750 ℃ tensile fracture according to an example of the present invention is shown in FIG. 3, and the microstructure in the vicinity of 750 ℃ tensile fracture according to a comparative example of the present invention is shown in FIG. 4. As is clear from the figure, the microstructure in the vicinity of fracture in the examples was martensite at the drawing temperature of 750 ℃ while the structure in the comparative examples began to precipitate ferrite along austenite grain boundaries, and the ferrite along the grains was easily cracked to form cracks, which is a factor of rapidly decreasing the reduction of area in the comparative examples at 700 to 850 ℃. The formation of intergranular ferrite was suppressed in the structure of the example as compared with the comparative example.
The microstructure near a 650 ℃ tensile fracture according to one embodiment of the invention is shown in figure 5. As is clear from fig. 5, when the stretching temperature was 650 ℃, a large amount of ferrite was present in the structure near the fracture surface of the example, ferrite precipitated as intragranular ferrite, no intergranular ferrite was present, and the ratio of intragranular ferrite in the structure exceeded 40%. Because the intragranular ferrite has good ductility and toughness, a large amount of ferrite exists in the intragranular ferrite form in the embodiment, and therefore, the generation of cracks can be effectively avoided in the continuous casting process.
In summary, for microalloyed steel, the invention controls the content of B in the casting blank to be 0.0010-0.0015% and the content of Ce to be 0.020-0.050% by adding a proper amount of B and Ce in the refining process, controls the temperature of the casting blank by cooling water in the continuous casting process, and fully exerts the synergistic effect of cooling control of boron, rare earth and the continuous casting process. Boron and rare earth which are dissolved in the steel are easy to be segregated at the grain boundary, so that the energy of the grain boundary is reduced, and the dragging effect of the dissolved Nb atoms on the grain boundary and dislocation is reduced, thereby playing the roles of purifying the grain boundary and promoting dynamic recrystallization, and inhibiting the formation of ferrite along the grain; rare earth Ce can remove coarse and large angular Al in steel 2 O 3 Modification of-MnS composite inclusion into fine and dispersedly distributed Ce 2 O 2 S rare earth inclusions, the linear expansion coefficients of which are similar to that of a steel matrix, are not easy to generate stress concentration when stressed, and are coordinated with the matrix when deformed; produced rare earth inclusions and Fe 23 (C,B) 6 Borides can be used as nucleation cores of intragranular ferrite, so that the generation amount of the intragranular ferrite is increased; the temperature of the casting blank is controlled to be in the formation interval of the intragranular ferrite by utilizing the cooling water, the content of the intragranular ferrite in the structure is further improved, and the precipitation of the ferrite in the casting blank in the form of the intragranular ferrite with good ductility and toughness is finally regulated and controlled, wherein the intragranular ferrite accounts for more than 40 percent. The thickness specification of the casting blank smelted according to the invention is 250mm, no surface crack defect is found by offline detection, and the reduction of area of the casting blank is higher than 70% within the range of 650-1050 ℃.
It should be noted that the above-mentioned embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (10)
1. The method for regulating and controlling the ferrite morphology in the casting blank structure is characterized by sequentially comprising molten iron pretreatment, converter smelting, LF refining, RH refining and continuous casting, wherein boron alloy and rare earth Ce alloy are added in the LF refining and RH refining processes, and the temperature of the casting blank is controlled in the continuous casting process.
2. The method according to claim 1, wherein 25 to 35t of scrap steel is added in the converter smelting process, the sulfur content in the scrap steel is less than or equal to 0.025 percent, and the proportion of molten iron fed into the converter is controlled to be 80 to 90 percent; adding silicomanganese and ferromanganese for deoxidation and alloying, and controlling the oxygen content of the steel tapping to be less than or equal to 0.050 percent.
3. The method of claim 1, wherein boron alloy is added during the LF refining, aluminum alloy and titanium alloy are sequentially added before the boron alloy is added, the temperature of the molten steel is more than 1580 ℃, and the total amount of B in the molten steel is 0.0010-0.0020% after the LF refining is finished.
4. The method as claimed in claim 1, wherein the rare earth Ce alloy is added in the RH refining process, the vacuum degree is 0.20kPa, the vacuum treatment time is more than 15min, the oxygen content in the molten steel is controlled to be less than or equal to 0.0020 percent, the nitrogen content is controlled to be less than or equal to 0.0030 percent, and the total content of the rare earth Ce in the molten steel after the RH refining is finished is 0.025-0.050 percent.
5. The method according to claim 1, wherein the surface temperature of the cast slab in the secondary cooling zone is controlled to be 630-920 ℃ and the surface temperature of the cast slab in the straightening zone is controlled to be higher than 1050 ℃.
6. The method as claimed in claim 5, wherein the continuous casting process employs a secondary cooling nozzle for gas-water atomization, and the surface temperature of the cast strand fluctuates in a range of 40 to 100 ℃.
7. A microalloyed steel, prepared by smelting according to the method for regulating and controlling the ferrite morphology in an ingot blank structure of any one of claims 1 to 6, wherein the microalloyed steel comprises the following chemical components in percentage by mass: 0.10 to 0.14%, si:0.20 to 0.35%, mn:1.4 to 1.7%, nb:0.04 to 0.07%, V:0.06 to 0.08%, al:0.010 to 0.040%, ti: 0.010-0.030%, N:0.0015 to 0.0030 percent of the total weight of the alloy, less than or equal to 0.0020 percent of O, less than or equal to 0.0060 percent of S, and the balance of iron and inevitable impurity elements, meanwhile, the content of B is 0.0010 to 0.0015 percent, and the content of rare earth Ce is 0.020 to 0.050 percent.
8. The microalloyed steel of claim 7, wherein the cast billet contains spherical or ellipsoidal Ce 2 O 2 S rare earth inclusions, the number of the rare earth inclusions is 300/mm 2 And the size of more than 85 percent of rare earth inclusions is less than 2 mu m.
9. The microalloyed steel according to claim 7, wherein the cast slab has no intergranular ferrite in a structure near a tensile fracture at 650-1050 ℃, ferrite is precipitated in an intragranular ferrite form, and the intragranular ferrite accounts for more than 40%.
10. The microalloyed steel according to claim 7, wherein the steel billet has no surface crack defects as measured and has a reduction of area >70% at 650-1050 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210547101.5A CN115216683B (en) | 2022-05-19 | 2022-05-19 | Method for regulating and controlling ferrite morphology in casting blank tissue and prepared microalloyed steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210547101.5A CN115216683B (en) | 2022-05-19 | 2022-05-19 | Method for regulating and controlling ferrite morphology in casting blank tissue and prepared microalloyed steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115216683A true CN115216683A (en) | 2022-10-21 |
| CN115216683B CN115216683B (en) | 2023-05-05 |
Family
ID=83608286
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210547101.5A Active CN115216683B (en) | 2022-05-19 | 2022-05-19 | Method for regulating and controlling ferrite morphology in casting blank tissue and prepared microalloyed steel |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115216683B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115710669A (en) * | 2022-11-16 | 2023-02-24 | 安徽工业大学 | Method for reducing harmfulness of residual element antimony in steel |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101818304A (en) * | 2010-03-23 | 2010-09-01 | 武汉钢铁(集团)公司 | Ultra-large linear energy input welding high-strength steel and production method thereof |
| CN103614608A (en) * | 2013-11-25 | 2014-03-05 | 马钢(集团)控股有限公司 | Production method of Q460C-grade high-strength steel |
| WO2016204288A1 (en) * | 2015-06-17 | 2016-12-22 | 新日鐵住金株式会社 | Steel sheet and manufacturing method |
| CN110129508A (en) * | 2019-05-23 | 2019-08-16 | 包头钢铁（集团）有限责任公司 | A kind of technique improving rare earth high-strength steel impact flexibility |
| CN111893240A (en) * | 2020-07-28 | 2020-11-06 | 北京科技大学 | Method for improving welding performance of Nb and Ti microalloyed steel by using rare earth |
| CN112626423A (en) * | 2020-12-15 | 2021-04-09 | 包头钢铁（集团）有限责任公司 | Production process for improving welding performance of rare earth high-strength steel |
| CN113348258A (en) * | 2019-05-09 | 2021-09-03 | 日本制铁株式会社 | Steel sheet and method for producing same |
| WO2021250450A1 (en) * | 2020-06-12 | 2021-12-16 | Arcelormittal | Cold rolled and heat-treated steel sheet and a method of manufacturing thereof |
-
2022
- 2022-05-19 CN CN202210547101.5A patent/CN115216683B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101818304A (en) * | 2010-03-23 | 2010-09-01 | 武汉钢铁(集团)公司 | Ultra-large linear energy input welding high-strength steel and production method thereof |
| CN103614608A (en) * | 2013-11-25 | 2014-03-05 | 马钢(集团)控股有限公司 | Production method of Q460C-grade high-strength steel |
| WO2016204288A1 (en) * | 2015-06-17 | 2016-12-22 | 新日鐵住金株式会社 | Steel sheet and manufacturing method |
| CN113348258A (en) * | 2019-05-09 | 2021-09-03 | 日本制铁株式会社 | Steel sheet and method for producing same |
| CN110129508A (en) * | 2019-05-23 | 2019-08-16 | 包头钢铁（集团）有限责任公司 | A kind of technique improving rare earth high-strength steel impact flexibility |
| WO2021250450A1 (en) * | 2020-06-12 | 2021-12-16 | Arcelormittal | Cold rolled and heat-treated steel sheet and a method of manufacturing thereof |
| CN111893240A (en) * | 2020-07-28 | 2020-11-06 | 北京科技大学 | Method for improving welding performance of Nb and Ti microalloyed steel by using rare earth |
| CN112626423A (en) * | 2020-12-15 | 2021-04-09 | 包头钢铁（集团）有限责任公司 | Production process for improving welding performance of rare earth high-strength steel |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115710669A (en) * | 2022-11-16 | 2023-02-24 | 安徽工业大学 | Method for reducing harmfulness of residual element antimony in steel |
| CN115710669B (en) * | 2022-11-16 | 2023-10-13 | 安徽工业大学 | Method for reducing harm of residual element antimony in steel |
Also Published As
| Publication number | Publication date |
|---|---|
| CN115216683B (en) | 2023-05-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111748741B (en) | Thick pipeline steel and low compression ratio production process thereof | |
| CN107385328B (en) | The low-alloy super-thick steel plate with superior internal quality, low-temperature impact toughness and anti-lamellar tearing performance of two base laminating productions | |
| CN112662933A (en) | Preparation method of low-temperature impact toughness-resistant wind power steel | |
| CN108929986B (en) | High-strength wear-resistant hot rolled steel plate for automobile braking and production process thereof | |
| CN110184532A (en) | A kind of wear-resisting steel plate and its production method with excellent -60 DEG C of ultralow temperature impact flexibility | |
| CN109652733B (en) | 690 MPa-grade super-thick steel plate and manufacturing method thereof | |
| CN114369764B (en) | High-performance thick hot-rolled H-shaped steel with yield strength of 460MPa and production method thereof | |
| CN110735085A (en) | Manufacturing method of thin Q345qE and Q370qE steel plates | |
| CN105112782A (en) | Low-temperature ferrite LT-FH40 steel plate applied to hot-rolled ships and production method thereof | |
| CN111979483A (en) | Method for producing Q345R steel plate by using conventional hot rolling production line | |
| CN110029268B (en) | 09MnNiDR steel plate for low-temperature pressure vessel with core low-temperature toughness protection and manufacturing method thereof | |
| CN102234742B (en) | A kind of steel plate for longitudinal welded pipe and manufacture method thereof | |
| CN111172462A (en) | 450 MPa-grade weathering steel and preparation method thereof | |
| JP2020509165A (en) | Extra-thick steel material excellent in surface portion NRL-DWT physical properties and method for producing the same | |
| WO2024001078A1 (en) | 80 mm thick 690 mpa-grade ultra-high strength and toughness marine steel plate and preparation method therefor | |
| CN113846260A (en) | Production method of high-strength steel plate for engineering machinery | |
| CN114717377B (en) | Continuous casting thick steel plate and production method thereof | |
| CN103160747A (en) | Low welding crack sensitivity off-line tempering super thick steel plate and manufacturing method thereof | |
| CN112048676A (en) | Strain aging resistant low-temperature toughness S420ML steel plate and production method thereof | |
| CN111270134A (en) | 400 MPa-grade weathering steel and preparation method thereof | |
| CN115216683A (en) | Method for regulating and controlling ferrite form in casting blank tissue and prepared microalloyed steel | |
| CN113957359A (en) | High-strength steel for automobile wheels and preparation method thereof | |
| CN115466905B (en) | Non-quenched and tempered steel with good corrosion resistance for 10.9-grade large-specification wind power bolts and production method thereof | |
| CN112680652A (en) | Cr-Mo low-alloy steel plate for pressure vessel and preparation method thereof | |
| CN114032454B (en) | Steel for PC prestressed steel wire and production process thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |