CN115595498B - Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate and preparation method thereof - Google Patents
Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate and preparation method thereof Download PDFInfo
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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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- 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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
Abstract
The invention discloses a Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate and a preparation method thereof, belonging to the technical field of high-strength high-toughness steel plates. The steel plate comprises the following chemical components in percentage by mass: c:0.02-0.05wt.%, si:0.20-0.30wt.%, mn:1.40 to 1.80wt.%, P is less than or equal to 0.008wt.%, S is less than or equal to 0.008wt.%, ti:0.08-0.20wt.%, mo:0.05-0.15wt.%, zr:0.01-0.07wt.%, balance Fe and unavoidable impurities. The steel plate has high strength, high toughness and low yield ratio, and is suitable for the fields of engineering machinery, heavy-duty bridges, energy-saving vehicles and the like.
Description
Technical Field
The invention belongs to the technical field of high-strength and high-toughness steel plates, and relates to a Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength and high-toughness steel plate and a preparation method thereof.
Background
In the prior art, the high-strength and high-toughness steel plate is generally obtained by precisely controlling the content of chemical elements in steel, a high-purity steel metallurgy technology, a heat treatment strengthening technology, a low-cost high-performance microalloying technology, a rolling control and cooling control technology and the like.
The method for precisely controlling the content of chemical elements in the steel and the metallurgical technology of the high-purity steel has the advantages of high cost, high operation difficulty, complex process and no contribution to industrial mass production and popularization.
The traditional high-strength and high-toughness steel plate is produced by a quenching and tempering heat treatment process (quenching and high-temperature tempering), and the steel has good strength and toughness, but has a very high yield ratio (more than 0.96), so that the steel is not beneficial to the application in certain fields.
In order to reduce the yield ratio of steel, the technology of quenching, two-phase zone secondary quenching and tempering is adopted at present, but for a high-strength and high-toughness medium plate, the growth of crystal grains is promoted by prolonging the heating time, so that the performance of the steel is reduced. Additional tempering heat treatment increases the manufacturing process and increases the manufacturing cost. Especially for hot rolled steel plates with yield strength up to 800MPa, the prior art needs to be subjected to micro-alloying such as Nb, ti, cu, ni, mo, B, tempering treatment is necessary, and relaxation time needs to be regulated.
Although the low-cost high-performance microalloying technology and the controlled rolling and cooling technology can respectively realize grain refinement of the steel plate, the strength and the toughness cannot be well matched, and then the high-strength high-toughness steel plate can be obtained only by matched heat treatment, so that the preparation process is complex, and the cost is high.
For example: chinese patent CN 113046635A discloses a high-strength and high-toughness corrosion-resistant steel for ocean engineering and a manufacturing method thereof, wherein the microalloying elements are Cr, mo, ni, V, B, the obtained material needs to be subjected to forging process and heat treatment process, and the performance can reach 800MPa level, but the preparation process is complex, the cost is high, the operation difficulty is high, and the industrial mass production is not facilitated.
Chinese patent CN105603322a discloses a steel sheet with ultra-low cost, 800 MPa-level high toughness and excellent weldability and a manufacturing method thereof, wherein the micro-alloying elements are Cr, mo, nb, ni, V, ti, B, al, ca, the number of the alloying elements is relatively large, the cost is relatively high, the obtained material needs tempering through a heat treatment process, the heat energy consumption and the cost are increased, the grain growth probability is increased, the tensile strength of 800 MPa-level is the tensile strength, the high-strength toughness hot rolling with the yield strength of 800 MPa-level cannot be equivalent to the heat treatment of the steel sheet, the low-temperature impact toughness is very high, but the yield strength is lower than 800MPa, and the elongation is also lower.
Chinese patent CN103131956a discloses a high strength and toughness steel plate with tensile strength of more than 800MPa and a manufacturing method thereof, wherein the microalloying elements are Cr, mo, V, ti, al, B, the alloy elements are more, the cost is higher, the heat treatment process of quenching and tempering is adopted to heat treat the rolled steel plate, the heat consumption is more, the crystal grains grow up, the tensile strength of the steel plate is more than or equal to 800MPa, the yield ratio is less than or equal to 0.92, and the low temperature impact toughness is higher, but the yield strength is less than 800 MPa.
In summary, in the prior art, a lot of 800 MPa-grade hot rolled steel plates need tempering treatment after hot rolling to improve tensile strength, yield strength and elongation, and obviously if the tempering treatment is not performed, the yield strength of the hot rolled steel plates cannot reach 800MPa grade, so that additional heat treatment is required, and the production cost is increased; and in other hot rolled steel plates, additional microalloying elements are required to be added, the preparation process is complex, the consumption cost is high, the operation difficulty is high, and the industrial mass production and popularization are not facilitated.
Disclosure of Invention
The technical problem to be solved by the invention is that the 800 MPa-grade hot rolled steel plate in the prior art needs an additional heat treatment process to correspondingly adjust the hot rolled structure, thereby increasing the production cost and having great operation difficulty; the element component has higher selection cost; the yield strength of the hot rolled steel plate with the thickness of 3-20mm, which is not subjected to the heat treatment process, is less than 800MPa, and the low-temperature impact toughness is not matched with the yield strength, the tensile strength and the elongation percentage, so that the production efficiency is low, and the hot rolled steel plate is not suitable for industrial production.
In order to solve the technical problems, the invention provides the following technical scheme:
a Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate comprises the following chemical components in percentage by mass: c:0.02-0.05wt.%, si:0.20-0.30wt.%, mn:1.40 to 1.80wt.%, P is less than or equal to 0.008wt.%, S is less than or equal to 0.008wt.%, ti:0.08-0.15wt.%, mo:0.05-0.15wt.%, zr:0.01-0.03wt.%, balance Fe and unavoidable impurities; wherein, ti: zr is 1.14:1-20:1, ti: mo 0.53:1-4:1, zr: mo 0.07:1-1.4:1, ti+Zr+Mo:0.14-0.42wt.%.
Preferably, the structure of the steel plate is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for more than 65%, and the average grain size of the steel plate is 2-5 μm.
Preferably, the thickness of the steel plate is 3-9mm, the yield strength is not less than 820MPa, the tensile strength is not less than 880MPa, the yield ratio is not more than 0.92, the elongation is more than 20%, the impact fracture absorption work at-20 ℃ is more than 90J, and the impact fracture absorption work at-40 ℃ is not less than 82J; the thickness of the steel plate is 10-20mm, the yield strength is not less than 800MPa, the tensile strength is not less than 880MPa, the yield ratio is not more than 0.91, the elongation is more than 20%, the impact fracture absorption power at-20 ℃ is more than 90J, and the impact fracture absorption power at-40 ℃ is not less than 80J.
The preparation method of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength and high toughness steel plate comprises the following specific steps:
s1, smelting process
Weighing raw materials, proportioning and smelting according to the mass percentages of the chemical components of the steel plate, and casting the steel plate blank after smelting is completed;
s2, heating process
Heating and preserving the steel plate blank in the step S1;
s3, rolling process
Air cooling the heated and insulated steel plate blank in the step S2, removing phosphorus, and then performing hot rolling, wherein the hot rolling comprises 2-3 times of rough rolling and 2-3 times of finish rolling to obtain a Ti-Zr composite micro-alloyed steel plate sample;
s4, cooling process
And (3) cooling the Ti-Zr composite microalloyed steel plate sample in the step (S3) to a coiling temperature by air, coiling, and then cooling to room temperature along with a furnace.
Preferably, in the smelting in the step S1, aluminum deoxidization is adopted in the tapping process, deep desulfurization deoxidization is performed in the LF refining process, and then Zr alloy and ferromolybdenum are added to ensure that the components of the Zr alloy and ferromolybdenum reach target components. Adding Ti alloy in RH refining process to station molten steel temperature 1600-1650 deg.C, vacuum treating for 10min, controlling nitrogen and sulfur content in molten steel to be less than 0.005% before adding Ti alloy, vacuum treating for 20min, and argon blowing and soft stirring for 5min.
Preferably, the temperature of heating and heat preservation in the step S2 is 1150-1250 ℃, and the heat preservation time is 1-3h.
Preferably, the air cooling in the step S3 is to control the cooling rate to be 2-7 ℃ per second until the temperature of the steel plate blank is reduced to 1000-1100 ℃.
Preferably, the initial rolling temperature of the rough rolling in the step S3 is 1000-1100 ℃, the final rolling temperature is 980+/-10 ℃, the reduction of each pass is more than 20%, the total reduction is 50-60%, and the structure is an austenite structure.
Preferably, the starting temperature of 2-3 pass finish rolling in the step S3 is a temperature at which the intermediate blank is heated to 960-975 ℃, the rolling reduction rate of each pass is more than 20%, and the final rolling temperature is 800-900 ℃.
Preferably, the thickness of the steel plate blank in the step S1 is 100-120mm, the thickness of the intermediate blank in the step S3 is 50-60mm, and the thickness of the Ti-Zr composite micro-alloyed steel plate sample in the step S3 is 3-20mm.
Preferably, the coiling temperature in the step S4 is 600-700 ℃, and the air cooling rate is controlled to be 2-7 ℃/S.
Compared with the prior art, the invention has the following beneficial effects:
in the scheme, the high strength, the high toughness and the low yield ratio are realized by designing alloy components, optimizing the rolling and cooling control technology and controlling the phase composition of the steel plate.
The invention adopts Ti-Zr-Mo composite addition, simultaneously accurately controls the contents of Ti, zr, mo and C, is designed for economic components, can improve yield strength and tensile strength, simultaneously does not reduce elongation, and improves low-temperature impact toughness; by adopting the controlled rolling and cooling production process, additional quenching and tempering heat treatment is not needed after rolling, thereby simplifying the manufacturing process and reducing the manufacturing cost of steel.
The structure of the steel plate is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for more than 65 percent, and the average grain size of the steel plate is 2-5 mu m.
The thickness of the steel plate prepared by the invention is 3-9mm, the yield strength is not less than 820MPa, the tensile strength is not less than 880MPa, the yield ratio is not more than 0.92, the elongation is more than 20%, the impact fracture absorption work at-20 ℃ is more than 90J, and the impact fracture absorption work at-40 ℃ is not less than 82J; the thickness of the steel plate is 10-20mm, the yield strength is not less than 800MPa, the tensile strength is not less than 880MPa, the yield ratio is not more than 0.91, the elongation is more than 20%, the impact fracture absorption power at-20 ℃ is more than 90J, and the impact fracture absorption power at-40 ℃ is not less than 80J.
The invention can meet the requirements of fields of engineering machinery, heavy-duty bridges, energy-saving vehicles, ocean platforms and the like in China on low-cost, high-strength, high-toughness and long-service-life steel, has strong adaptability and popularization value, and has relatively high cost performance and popularization market.
In a word, the Ti-Zr-Mo composite microalloyed 800 MPa-grade high-strength high-toughness steel plate and the preparation method thereof provided by the invention can improve the strength, plasticity and low-temperature impact toughness of the prepared material by utilizing Ti-Zr-Mo composite addition, the thickness of the prepared steel plate is 3-20mm, the industrial mass production and popularization and application are facilitated, and the steel plate is suitable for the fields of engineering machinery, heavy-load bridges, energy-saving vehicles, ocean platforms and the like.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a diagram showing the morphology of a metallographic structure of a Ti-Zr-Mo composite microalloyed 800 MPa-level high strength high toughness steel sheet according to example 1 of the present invention;
FIG. 2 is a diagram showing the morphology of a metallographic structure of a Ti-Zr-Mo composite microalloyed 800 MPa-level high strength high toughness steel sheet according to example 2 of the present invention;
FIG. 3 is a diagram showing the morphology of a metallographic structure of a Ti-Zr-Mo composite microalloyed 800 MPa-level high strength high toughness steel sheet according to example 3 of the present invention;
FIG. 4 is a diagram showing the morphology of a metallographic structure of a Ti-Zr-Mo composite microalloyed 800 MPa-level high strength high toughness steel sheet according to example 4 of the present invention;
FIG. 5 is a diagram showing the morphology of a metallographic structure of a Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel sheet according to example 5 of the present invention;
FIG. 6 is a diagram showing the morphology of a metallographic structure of a Ti-Zr-Mo composite microalloyed 800 MPa-level high strength and high toughness steel sheet according to example 6 of the present invention.
Detailed Description
The technical solutions and the technical problems to be solved in the embodiments of the present invention will be described below in conjunction with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present patent.
Example 1
A Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with the thickness of 10mm comprises the following chemical components in percentage by mass: 0.05wt.%, si:0.215wt.%, mn:1.51wt.%, P:0.005wt.%, S:0.002wt.%, ti:0.148wt.% Mo:0.05wt.%, zr:0.015wt.%, balance Fe and unavoidable impurities; wherein, ti: zr: mo is 148:50:15, ti+Zr+Mo: 0.213wt.%.
The specific process steps of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate are as follows:
s1, smelting process
Weighing raw materials, proportioning and smelting according to the mass percentages of the chemical components of the steel plate, and casting into a steel plate blank with the thickness of 100mm after smelting;
s2, heating process
Heating and preserving the steel plate blank in the step S1, wherein the temperature of heating and preserving the heat is 1250 ℃, and the preserving time is 2h;
s3, rolling process
Air cooling the heated and insulated steel plate blank in the step S2, wherein the cooling rate is controlled at 5 ℃/S until the temperature of the steel plate blank is reduced to 1050 ℃; and then dephosphorizing, and then carrying out hot rolling, wherein the hot rolling comprises 2-3 times of rough rolling and 2-3 times of finish rolling, wherein the 2-3 times of rough rolling is carried out at a rough rolling start temperature of 1035 ℃ and a finish rolling temperature of 980 ℃, the rolling reduction of each time is 25%, and the total rolling reduction is 50%. The structure is an austenite structure, the starting temperature of 2-3 passes of finish rolling is the temperature of the intermediate billet to be heated to 970 ℃, the thickness of the intermediate billet is 50mm, the rolling reduction rate of each pass is more than 20%, and the final rolling temperature is 850 ℃; obtaining a Ti-Zr-Mo composite microalloyed steel plate sample with the thickness of 10 mm;
s4, cooling process
And (3) carrying out water cooling on the Ti-Zr-Mo composite microalloyed steel plate sample in the step (S3) to the coiling temperature of 600 ℃, controlling the water cooling rate within a certain range, coiling, and then cooling to room temperature along with a furnace to obtain the Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 10 mm.
The microstructure of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with the thickness of 10mm prepared in the embodiment is shown in figure 1, the microstructure is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for 68%, and the average grain size of the steel plate is 3.1 μm. Mechanical properties: the yield strength is 807MPa, the tensile strength is 885MPa, the after-break expansion rate is 20.8%, the impact fracture absorption power at-20 ℃ is 92J, and the impact fracture absorption power at-40 ℃ is 80J.
The Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 10mm prepared by the embodiment can be applied to any one of the fields of engineering machinery, heavy-duty bridges, energy-saving vehicles, ocean platforms and the like.
Example 2
A Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with thickness of 6mm comprises the following chemical components in percentage by mass: 0.05wt.%, si:0.215wt.%, mn:1.51wt.%, P:0.005wt.%, S:0.002wt.%, ti:0.148wt.% Mo:0.07wt.%, zr:0.02wt.%, balance Fe and unavoidable impurities; wherein, ti: zr: mo is 37:15:5, ti+Zr+Mo: 0.238wt.%.
The specific process steps of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate are as follows:
s1, smelting process
Weighing raw materials, proportioning and smelting according to the mass percentages of the chemical components of the steel plate, and casting into a steel plate blank with the thickness of 100mm after smelting;
s2, heating process
Heating and preserving the heat of the steel plate blank in the step S1, wherein the heating and preserving temperature is 1150 ℃, and the preserving time is 1h;
s3, rolling process
Air cooling the heated and insulated steel plate blank in the step S2, wherein the cooling rate is controlled at 7 ℃/S until the temperature of the steel plate blank is reduced to 1000 ℃; then dephosphorizing, and then carrying out hot rolling, wherein the hot rolling comprises 2-3 times of rough rolling and 2-3 times of finish rolling, the 2-3 times of rough rolling is carried out at a rough rolling start temperature of 1000 ℃, a finish rolling temperature of 990 ℃, the reduction of each time is more than 20%, the total reduction is 50%, the structure is an austenitic structure, the starting temperature of the 2-3 times of finish rolling is the temperature of a middle blank to be heated to 960 ℃, the thickness of the middle blank is 50mm, the reduction rate of each time of rolling is more than 20%, and the finish rolling temperature is 830 ℃; obtaining a Ti-Zr-Mo composite microalloyed steel plate sample with the thickness of 6 mm;
s4, cooling process
And (3) air cooling the Ti-Zr-Mo composite microalloyed steel plate sample in the step (S3) to the coiling temperature of 600 ℃, controlling the air cooling rate to 7 ℃/S, coiling, and then cooling to room temperature along with a furnace to obtain the Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 6 mm.
The microstructure of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with the thickness of 6mm prepared in the embodiment is shown in figure 2, the microstructure is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for 78%, and the average grain size of the steel plate is 2.8 mu m. Mechanical properties: the yield strength is 835MPa, the tensile strength is 902MPa, the after-break expansion rate is 21.7%, the impact fracture absorption power at-20 ℃ is 98J, and the impact fracture absorption power at-40 ℃ is 82J.
The Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 6mm prepared by the embodiment can be applied to any one of the fields of engineering machinery, heavy-duty bridges, energy-saving vehicles, ocean platforms and the like.
Example 3
A Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with thickness of 12mm comprises the following chemical components in percentage by mass: 0.04wt.%, si:0.245wt.%, mn:1.48wt.%, P:0.005wt.%, S:0.003wt.%, ti:0.2wt.% Mo:0.15wt.%, zr:0.07wt.%, balance Fe and unavoidable impurities; wherein, ti: zr: mo is 20:15:7, ti+Zr+Mo: 0.42wt.%.
The specific process steps of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate are as follows:
s1, smelting process
Weighing raw materials, proportioning and smelting according to the mass percentages of the chemical components of the steel plate, and casting into a steel plate blank with the thickness of 120mm after smelting;
s2, heating process
Heating and preserving the heat of the steel plate blank in the step S1, wherein the temperature of the heating and preserving the heat is 1205 ℃, and the preserving time is 3h;
s3, rolling process
Air cooling the heated and insulated steel plate blank in the step S2, wherein the cooling rate is controlled to be 4 ℃/S until the temperature of the steel plate blank is reduced to 1080 ℃; then dephosphorizing, and then carrying out hot rolling, wherein the hot rolling comprises 2-3 times of rough rolling and 2-3 times of finish rolling, the 2-3 times of rough rolling is carried out at the initial rolling temperature of 1050 ℃ and the final rolling temperature of 980 ℃, the rolling reduction of each time is 25%, the total rolling reduction is 50%, the structure is an austenitic structure, the starting temperature of the 2-3 times of finish rolling is the temperature of the intermediate billet to be at the temperature of 970 ℃, the thickness of the intermediate billet is 60mm, the rolling reduction of each time is more than 20%, and the final rolling temperature is 850 ℃; obtaining a Ti-Zr-Mo composite microalloyed steel plate sample with the thickness of 12 mm;
s4, cooling process
And (3) air cooling the Ti-Zr-Mo composite microalloyed steel plate sample in the step (S3) to a coiling temperature of 650 ℃, controlling the air cooling rate to be 4 ℃/S, coiling, and then cooling to room temperature along with a furnace to obtain the Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 12 mm.
The microstructure of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with the thickness of 12mm prepared in the embodiment is shown in figure 3, the microstructure is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for 71%, and the average grain size of the steel plate is 3.3 μm. Mechanical properties: the yield strength is 905MPa, the tensile strength is 980MPa, the expansion rate after fracture is 22%, the impact fracture absorption power at-20 ℃ is 91J, and the impact fracture absorption power at-40 ℃ is 79J.
The Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 12mm prepared by the embodiment can be applied to any one of the fields of engineering machinery, heavy-duty bridges, energy-saving vehicles, ocean platforms and the like.
Example 4
A Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with a thickness of 15mm comprises the following chemical components in percentage by mass: 0.04wt.%, si:0.215wt.%, mn:1.41wt.%, P:0.005wt.%, S:0.002wt.%, ti:0.158wt.% Mo:0.07wt.%, zr:0.045wt.%, balance Fe and unavoidable impurities; wherein, ti: zr: mo is 158:70:45, ti+Zr+Mo: 0.273wt.%.
The specific process steps of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate are as follows:
s1, smelting process
Weighing raw materials, proportioning and smelting according to the mass percentages of the chemical components of the steel plate, and casting into a steel plate blank with the thickness of 100mm after smelting;
s2, heating process
Heating and preserving the heat of the steel plate blank in the step S1, wherein the temperature of the heating and preserving the heat is 1200 ℃, and the preserving time is 1h;
s3, rolling process
Air cooling the heated and insulated steel plate blank in the step S2, wherein the cooling rate is controlled at 5 ℃/S until the temperature of the steel plate blank is reduced to 1050 ℃; then dephosphorizing, and then carrying out hot rolling, wherein the hot rolling comprises 2-3 times of rough rolling and 2-3 times of finish rolling, the 2-3 times of rough rolling is carried out at a rough rolling start temperature of 1035 ℃, a finish rolling temperature of 1000 ℃, a rolling reduction of 20% per time, a total rolling reduction of 40%, a structure of austenite, the 2-3 times of finish rolling start temperature is a temperature at which an intermediate billet is to be heated to 975 ℃, the thickness of the intermediate billet is 60mm, the rolling reduction rate of each time is more than 20%, and the finish rolling temperature is 820 ℃; obtaining a Ti-Zr-Mo composite microalloyed steel plate sample with the thickness of 15 mm;
s4, cooling process
And (3) air cooling the Ti-Zr-Mo composite microalloyed steel plate sample in the step (S3) to a coiling temperature of 700 ℃, controlling the air cooling rate to 5 ℃/S, coiling, and then cooling to room temperature along with a furnace to obtain the Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 15 mm.
The microstructure of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with the thickness of 15mm prepared in the example is shown in fig. 4, the microstructure is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for 73%, and the average grain size of the steel plate is 2.8 μm. Mechanical properties: the yield strength is 833MPa, the tensile strength is 925MPa, the expansion rate after fracture is 22.5%, the impact fracture absorption power at-20 ℃ is 98J, and the impact fracture absorption power at-40 ℃ is 83J.
The Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 15mm prepared by the embodiment can be applied to any one of the fields of engineering machinery, heavy-duty bridges, energy-saving vehicles, ocean platforms and the like.
Example 5
A Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with the thickness of 10mm comprises the following chemical components in percentage by mass: 0.05wt.%, si:0.271wt.% Mn:1.60wt.%, P:0.005wt.%, S:0.005wt.%, ti:0.138wt.% Mo:0.12wt.%, zr:0.035wt.%, balance Fe and unavoidable impurities; wherein, ti: zr: mo is 138:120:35, ti+Zr+Mo:0.293wt.%.
The specific process steps of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate are as follows:
s1, smelting process
Weighing raw materials, proportioning and smelting according to the mass percentages of the chemical components of the steel plate, and casting into a steel plate blank with the thickness of 100mm after smelting;
s2, heating process
Heating and preserving the heat of the steel plate blank in the step S1, wherein the heating and preserving temperature is 1150 ℃, and the preserving time is 2h;
s3, rolling process
Air cooling the heated and insulated steel plate blank in the step S2, wherein the cooling rate is controlled at 3 ℃/S until the temperature of the steel plate blank is reduced to 1035 ℃; then dephosphorizing, and then carrying out hot rolling, wherein the hot rolling comprises 2-3 times of rough rolling and 2-3 times of finish rolling, the 2-3 times of rough rolling is carried out at the initial rolling temperature of 1000 ℃ and the final rolling temperature of 980 ℃, the rolling reduction of each time is 25%, the total rolling reduction is 50%, the structure is an austenitic structure, the starting temperature of the 2-3 times of finish rolling is the temperature of the intermediate billet to 968 ℃, the thickness of the intermediate billet is 50mm, the rolling reduction rate of each time is more than 20%, and the final rolling temperature is 870 ℃; obtaining a Ti-Zr-Mo composite microalloyed steel plate sample with the thickness of 10 mm;
s4, cooling process
And (3) air cooling the Ti-Zr-Mo composite microalloyed steel plate sample in the step (S3) to a coiling temperature of 650 ℃, controlling the air cooling rate to 3 ℃/S, coiling, and then cooling to room temperature along with a furnace to obtain the Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 10 mm.
The microstructure of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with the thickness of 10mm prepared in the example is shown in FIG. 5, the microstructure is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for 75%, and the average grain size of the steel plate is 2.8 μm. Mechanical properties: the yield strength is 812MPa, the tensile strength is 894MPa, the after-break expansion rate is 20.5%, the impact fracture absorption power at-20 ℃ is 101J, and the impact fracture absorption power at-40 ℃ is 89J.
The Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 10mm prepared by the embodiment can be applied to any one of the fields of engineering machinery, heavy-duty bridges, energy-saving vehicles, ocean platforms and the like.
Example 6
A Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with the thickness of 20mm comprises the following chemical components in percentage by mass: 0.05wt.%, si:0.215wt.%, mn:1.51wt.%, P:0.005wt.%, S:0.002wt.%, ti:0.148wt.% Mo:0.10wt.%, zr:0.035wt.%, balance Fe and unavoidable impurities; wherein, ti: zr: mo is 148:100:35, ti+Zr+Mo: 0.283wt.%.
The specific process steps of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate are as follows:
s1, smelting process
Weighing raw materials, proportioning and smelting according to the mass percentages of the chemical components of the steel plate, and casting into a steel plate blank with the thickness of 100mm after smelting;
s2, heating process
Heating and preserving the heat of the steel plate blank in the step S1, wherein the heating and preserving temperature is 1150 ℃, and the preserving time is 3h;
s3, rolling process
Air cooling the heated and insulated steel plate blank in the step S2, wherein the cooling rate is controlled at 7 ℃/S until the temperature of the steel plate blank is reduced to 1000-1100 ℃; then dephosphorizing, and then carrying out hot rolling, wherein the hot rolling comprises 2-3 times of rough rolling and 2-3 times of finish rolling, the 2-3 times of rough rolling is carried out at the initial rolling temperature of the rough rolling of 1000 ℃, the finish rolling temperature of 980 ℃, the reduction of each time is more than 25%, the total reduction of 50%, the structure is an austenitic structure, the starting temperature of the 2-3 times of finish rolling is the temperature of the intermediate billet to be at 975 ℃, the thickness of the intermediate billet is 60mm, the reduction rate of each time of rolling is more than 20%, and the finish rolling temperature is 890 ℃; obtaining a Ti-Zr-Mo composite microalloyed steel plate sample with the thickness of 20 mm;
s4, cooling process
And (3) air cooling the Ti-Zr-Mo composite microalloyed steel plate sample in the step (S3) to the coiling temperature of 600 ℃, controlling the air cooling rate to 7 ℃/S, coiling, and then cooling to room temperature along with a furnace to obtain the Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 20mm.
The microstructure of the Ti-Zr-Mo composite microalloyed 800MPa grade high strength high toughness steel plate with the thickness of 20mm prepared in the example is shown in FIG. 6, the microstructure is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for 68%, and the average grain size of the steel plate is 3.2 μm. Mechanical properties: the yield strength is 805MPa, the tensile strength is 882MPa, the after-break expansion rate is 20.5%, the impact fracture absorption power at-20 ℃ is 92J, and the impact fracture absorption power at-40 ℃ is 87J.
The Ti-Zr-Mo composite microalloyed 800 MPa-level high-strength high-toughness steel plate with the thickness of 20mm prepared by the embodiment can be applied to any one of the fields of engineering machinery, heavy-duty bridges, energy-saving vehicles, ocean platforms and the like.
In summary, the comparison of examples 1-6 shows that the Ti-Zr-Mo composite addition increases yield strength and tensile strength while simultaneously not decreasing elongation, and increases low temperature impact toughness.
In the scheme, the high strength, the high toughness and the low yield ratio are realized by designing alloy components, optimizing the rolling and cooling control technology and controlling the phase composition of the steel plate.
The invention adopts Ti-Zr-Mo composite addition, simultaneously accurately controls the contents of Ti, zr, mo and C, is designed for economic components, can improve yield strength and tensile strength, simultaneously does not reduce elongation, and improves low-temperature impact toughness; by adopting the controlled rolling and cooling production process, additional quenching and tempering heat treatment is not needed after rolling, thereby simplifying the manufacturing process and reducing the manufacturing cost of steel.
The structure of the steel plate is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for more than 65 percent, and the average grain size of the steel plate is 2-5 mu m.
The thickness of the steel plate prepared by the invention is 3-9mm, the yield strength is not less than 820MPa, the tensile strength is not less than 880MPa, the yield ratio is not more than 0.92, the elongation is more than 20%, the impact fracture absorption work at-20 ℃ is more than 90J, and the impact fracture absorption work at-40 ℃ is not less than 82J; the thickness of the steel plate is 10-20mm, the yield strength is not less than 800MPa, the tensile strength is not less than 880MPa, the yield ratio is not more than 0.91, the elongation is more than 20%, the impact fracture absorption power at-20 ℃ is more than 90J, and the impact fracture absorption power at-40 ℃ is not less than 80J.
The invention can meet the requirements of fields of engineering machinery, heavy-duty bridges, energy-saving vehicles, ocean platforms and the like in China on low-cost, high-strength, high-toughness and long-service-life steel, has strong adaptability and popularization value, and has relatively high cost performance and popularization market.
In a word, the Ti-Zr-Mo composite microalloyed 800 MPa-grade high-strength high-toughness steel plate and the preparation method thereof provided by the invention can improve the strength, plasticity and low-temperature impact toughness of the prepared material by utilizing Ti-Zr-Mo composite addition, the thickness of the prepared steel plate is 3-20mm, the industrial mass production and popularization and application are facilitated, and the steel plate is suitable for the fields of engineering machinery, heavy-load bridges, energy-saving vehicles, ocean platforms and the like.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.
Claims (8)
1. The Ti-Zr-Mo composite microalloyed 800MPa grade high strength and high toughness steel plate is characterized by comprising the following chemical components in percentage by mass: c:0.02-0.05wt.%, si:0.20-0.30wt.%, mn:1.40 to 1.80wt.%, P is less than or equal to 0.008wt.%, S is less than or equal to 0.008wt.%, ti:0.08-0.20wt.%, mo:0.05-0.15wt.%, zr:0.01-0.07wt.%, balance Fe and unavoidable impurities; wherein, ti: zr is 1.14:1-20:1, ti: mo 0.53:1-4:1, zr: mo 0.07:1-1.4:1, ti+Zr+Mo:0.14-0.42wt.%;
the structure of the steel plate is a polygonal ferrite and acicular ferrite structure, the acicular ferrite accounts for more than 65%, and the average grain size of the steel plate is 2-5 mu m;
the thickness of the steel plate is 3-9mm, the yield strength is not less than 820MPa, the tensile strength is not less than 880MPa, the yield ratio is not more than 0.92, the elongation is more than 20%, the impact fracture absorption power at-20 ℃ is more than 90J, and the impact fracture absorption power at-40 ℃ is not less than 82J; the thickness of the steel plate is 10-20mm, the yield strength is not less than 800MPa, the tensile strength is not less than 880MPa, the yield ratio is not more than 0.91, the elongation is more than 20%, the impact fracture absorption power at-20 ℃ is more than 90J, and the impact fracture absorption power at-40 ℃ is not less than 80J.
2. The method for preparing the Ti-Zr-Mo composite microalloyed 800MPa grade high strength and high toughness steel plate according to claim 1, wherein the specific steps of the preparation method are as follows:
s1, smelting process
Weighing raw materials, proportioning and smelting according to the mass percentage of the chemical components of the steel plate, and casting the steel plate blank after smelting;
s2, heating process
Heating and preserving the steel plate blank in the step S1;
s3, rolling process
Air cooling the heated and insulated steel plate blank in the step S2, descaling, and then hot rolling, wherein the hot rolling comprises 2-3 times of rough rolling and 2-3 times of finish rolling, so as to obtain a Ti-Zr composite micro-alloyed steel plate sample;
s4, cooling process
And (3) cooling the Ti-Zr composite microalloyed steel plate sample in the step (S3) to a coiling temperature by air, coiling, and then cooling to room temperature along with a furnace.
3. The method for preparing the Ti-Zr-Mo composite microalloyed 800 MPa-level high strength and high toughness steel sheet according to claim 2, wherein the heating and heat preservation temperature in the step S2 is 1150-1250 ℃, and the heat preservation time is 1-3h.
4. The method for preparing a Ti-Zr-Mo composite micro-alloyed 800 MPa-level high-strength high-toughness steel plate according to claim 2, wherein the air cooling in step S3 is to control the cooling rate to 2-7 ℃/S until the temperature of the steel plate blank is reduced to 1000-1100 ℃.
5. The method for preparing the Ti-Zr-Mo composite microalloyed 800 MPa-level high strength and high toughness steel sheet according to claim 2, wherein the rough rolling start temperature of the 2-3 pass rough rolling in the step S3 is 1000-1100 ℃, the finish rolling temperature is 980±10 ℃, the reduction of each pass is more than 20%, the total reduction is 50-60%, and the structure is an austenitic structure.
6. The method for producing a Ti-Zr-Mo composite micro-alloyed 800 MPa-level high strength and high toughness steel sheet according to claim 2, wherein the 2-3 pass finish rolling start temperature in step S3 is a temperature at which the intermediate blank is to be heated to 960-975 ℃, rolling reduction rate per pass is >20%, and finishing temperature is 800-900 ℃.
7. The method for producing a Ti-Zr-Mo composite microalloyed 800 MPa-level high strength and high toughness steel sheet according to claim 2, wherein the thickness of the steel sheet slab in said step S1 is 100 to 120mm, the thickness of the intermediate blank in said step S3 is 50 to 60mm, and the thickness of the Ti-Zr composite microalloyed steel sheet sample in said step S3 is 3 to 20mm.
8. The method for producing a Ti-Zr-Mo composite microalloyed 800 MPa-level high strength and high toughness steel sheet according to claim 2, wherein the coiling temperature in said step S4 is 600-700 ℃, and the air cooling rate is controlled to 2-7 ℃/S.
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