CN109136779B - Preparation method of 1100 MPa-level rare earth Q & P steel with martensite matrix - Google Patents

Preparation method of 1100 MPa-level rare earth Q & P steel with martensite matrix Download PDF

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CN109136779B
CN109136779B CN201810924896.0A CN201810924896A CN109136779B CN 109136779 B CN109136779 B CN 109136779B CN 201810924896 A CN201810924896 A CN 201810924896A CN 109136779 B CN109136779 B CN 109136779B
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casting blank
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CN109136779A (en
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景财年
丁啸云
邢兆贺
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山东建筑大学
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226Hot rolling
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/002Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/005Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/06Ferrous alloys, e.g. steel alloys containing aluminium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/12Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D2211/00Microstructure comprising significant phases
    • C21D2211/008Martensite

Abstract

The invention relates to a preparation method of a martensite matrix 1100 MPa-grade rare earth Q & P steel, which comprises the following components: 0.15 to 0.22%, Si: 0.60 to 1.70%, Mn: 1.10-2.40%, Mo: 0.1-0.5%, Al: 0.1-0.5%, V: 0.05-0.11%, Y: 0.01-0.05%, P: 0.02-0.04%, S is less than or equal to 0.005%, Nb: 0.040-0.0700%, N is less than or equal to 0.0060%, B: 0.001 to 0.006% and the balance of Fe and unavoidable impurities. Smelting in a converter after batching, refining in a vacuum furnace, continuously casting to obtain a casting blank, adding trace alloy element powder into an electric arc smelting furnace to obtain a secondary casting blank, and heating and hot rolling; cold rolling after acid washing; then heating to a two-phase region for heat preservation; carbon partitioning and tempering to obtain the final structure. According to the invention, through a proper amount of a plurality of beneficial alloy elements, the contents of C, Si, Mn and other elements in the traditional steel are reduced, the weldability and corrosion resistance are enhanced, crystal grains are refined, and the produced steel plate has good comprehensive mechanical properties, and is beneficial to automobile light weight, energy conservation and emission reduction.

Description

Preparation method of 1100 MPa-level rare earth Q & P steel with martensite matrix
Technical Field
The invention relates to the field of ferrous metallurgy and manufacturing, in particular to a preparation method of a martensite matrix 1100 MPa-level rare earth Q & P steel.
Background
According to the data of the ministry of public security, the number of motor vehicles in the country reaches 3.10 hundred million by 2017. 3352 motor vehicles newly registered and registered in a public security traffic management department in 2017 have high innovation history. The number of cars is 2.17 hundred million, and compared with 2016, 2304 million cars are increased all the year round, and the increase is 11.85%. The proportion of automobiles in automobiles is continuously increasing, and the proportion of automobiles in automobiles is increased from 54.93% to 70.17% in recent five years, so that automobiles become a main constituent of automobiles. Meanwhile, related tests show that the oil consumption can be reduced by 6-8% and the emission can be reduced by 4% when the mass of the automobile is reduced by 10%.
At present, although China obtains the first automobile sales in the world for 9 years continuously, the automobile quantity of each thousand people is 140, and the automobile quantity is far from that of developed countries and still has huge space. Therefore, higher requirements are put on advanced high-strength steel. The advanced high-strength steel fully plays a role in phase transformation strengthening on the basis of the traditional strengthening means, and simultaneously obtains a complex phase structure containing two or more phases of martensite, bainite, ferrite and retained austenite by matching with a proper heat treatment process means, so that each phase structure fully plays the characteristics of the advanced high-strength steel, and the respective defects or shortcomings are weakened or eliminated due to the existence of other phases, thereby achieving the purpose of improving the comprehensive performance of the steel. Representative advanced high-strength steels studied and developed in recent years include martensite (M) steel, Dual Phase (DP) steel, transformation induced plasticity (TRIP) steel, carbide-free bainite/martensite complex phase (CFB/M) steel, twin induced plasticity (TWIP) steel, and nano bainite (B) steel, etc. Q & P steel is widely concerned and researched as advanced high-strength steel with good comprehensive mechanical properties.
The existing Q & P steel production process has the following problems: (1) quenching-partitioning treatment is mostly carried out after the existing steel grade is completely annealed, namely, the material is completely austenitized twice, so that on one hand, great energy waste is caused, and on the other hand, a great deal of time is wasted in the complete annealing process; (2) the cost is reduced, and the simple structure adjustment is carried out by only regulating the content of the C element and utilizing Mn and Si elements. However, too high a content of C element seriously affects the welding property while increasing brittleness; (3) part of high-strength steel only focuses on strength or plasticity, and the product of strength and plasticity is low, so that the requirement of modern automobiles cannot be met; (4) the heat treatment process is complex, the production technical requirement is high, a novel instrument with high price needs to be purchased for realizing industrialization, and the equipment management and maintenance cost is relatively high.
Disclosure of Invention
In order to improve and solve the defects, the invention provides a preparation method of the 1100 MPa-grade rare earth Q & P steel with the martensite matrix by reasonably designing the original components and the treatment process of the steel, can greatly improve the comprehensive mechanical property, reduces the process steps, saves energy, and has the characteristics of low cost and high production efficiency.
In order to achieve the purpose, the invention adopts the technical scheme that:
the invention comprises the following components: c: 0.15 to 0.22%, Si: 0.60 to 1.70%, Mn: 1.10-2.40%, Mo: 0.1-0.5%, Al: 0.1-0.5%, V: 0.05-0.11%, Y: 0.01-0.05%, P: 0.02-0.04%, S is less than or equal to 0.005%, Nb: 0.040-0.0700%, N is less than or equal to 0.0060%, B: 0.001 to 0.006% and the balance of Fe and unavoidable impurities.
The principle of component design is as follows:
when the carbon content exceeds 0.23 percent, the welding performance of the steel is remarkably reduced, and simultaneously, the atmospheric corrosion resistance of the steel is reduced due to the increase of the carbon content, so that the high-carbon steel in an open material yard is easy to rust; in addition, carbon can increase the cold brittleness and age sensitivity of the steel. Therefore, the content of the C element designed by the invention is 0.15-0.22%;
si: silicon is an element added to steel as a deoxidizer in steel making. Silicon is a beneficial element because it forms a less dense silicate slag with the FeO in the molten steel and is removed. Silicon is dissolved in ferrite in steel to increase the strength and hardness of the steel and reduce the plasticity and toughness. Silicon can significantly improve the elastic limit, yield point and tensile strength of steel. When the silicon content in the steel is not more than 0.5%, the influence on the performance of the steel is small, so that the Si element content designed by the invention is 0.60-1.70%;
mn: manganese is added to steel as a deoxidizer during steel making. Since manganese can form high melting point (1600 ℃) MnS with sulfur, the detrimental effects of sulfur are eliminated to some extent. Manganese has good deoxidizing capacity and can be converted into MnO together with FeO in steel to enter slag, so that the quality of the steel is improved, the brittleness of the steel is particularly reduced, and the strength and the hardness of the steel are improved. Therefore, manganese is a beneficial element in steel, and when more than 0.70 percent of manganese is added, the hardenability of the steel can be effectively improved, and the hot workability of the steel can be improved. However, the manganese content is too high, so that the corrosion resistance of the steel is weakened, and the welding performance is reduced, so that the Mn element content designed by the invention is 1.10-2.40%;
mo: the method can obviously improve the hardenability and the heat strength of the steel, prevent the tempering brittleness, improve the remanence and the coercive force, refine the crystal grains of the steel and keep enough strength and creep resistance at high temperature. The addition of molybdenum into the steel can improve the mechanical property, inhibit the brittleness of the alloy steel caused by tempering, and improve the corrosion resistance to a certain extent, so that the content of the Mo element designed by the invention is 0.1-0.5%;
al can refine the grain structure of the steel, inhibit the aging of the low-carbon steel, improve the toughness of the steel at low temperature, improve the oxidation resistance of the steel, improve the wear resistance and fatigue strength of the steel and the like. Therefore, the content of the Al element designed by the invention is 0.1-0.5%;
v: the refined crystal grains have strong effect, the strength and the toughness of the steel can be improved, the overheating sensitivity is reduced, and the thermal stability is improved. The tempering stability of the M body is improved. VC has high dispersity and is very stable. Therefore, the oxygen can be removed and the gas can be removed. The compact fine crystal structure is obtained, the plasticity, the toughness and the high strength are improved, the impact property and the fatigue strength are higher than those of V-free steel, and the high strength and the toughness are realized at high temperature and low temperature (less than 0 ℃). The high dispersion of vanadium carbide prevents coarse grains of a weld joint, so that the weldability of steel can be improved, but steel grains can be caused to grow strongly after the steel is heated to the VC dissolving temperature, so that the content of the V element designed by the invention is 0.05-0.11%;
y: the steel has the effects of degassing, desulfurizing and eliminating other harmful impurities, the cast structure of the steel is improved, the oxidation resistance, the high-temperature strength and the creep strength can be improved by extremely low content, and the corrosion resistance is increased, so that the content of the Y element designed by the invention is 0.01-0.05%;
n: ferrite has a low ability to dissolve nitrogen. When supersaturated nitrogen is dissolved in the steel, the nitrogen is precipitated in a nitride form after the steel is placed for a long period of time or is heated at 200-300 ℃, so that the hardness and the strength of the steel are improved, the plasticity is reduced, and the aging is performed. Al, Ti or V is added into the molten steel for nitrogen fixation treatment, so that nitrogen is fixed in AlN, TiN or VN, and the aging tendency can be eliminated. Therefore, the content of the N element designed by the invention is 0.006%;
s: sulfur is derived from steel making ores and fuel coke. It is a harmful element in steel. Sulphur is present in the steel in the form of iron sulphide (FeS), which forms low melting (985 ℃) compounds with Fe. Since the hot working temperature of steel is generally 1150 to 1200 ℃ or higher, when steel is hot worked, the work is cracked due to premature melting of FeS compounds, which is called "hot embrittlement". The higher the sulfur content, the more severe the hot shortness phenomenon, so the sulfur content in the steel must be controlled. Therefore, the content of the S element designed by the invention is less than or equal to 0.005 percent;
b: when the steel contains a trace amount (0.001-0.005%) of boron, the hardenability of the steel can be improved by times, and at this time, other properties and the like are not affected or are little affected, but when the content of B exceeds 0.007%, brittleness is easily caused, and therefore, the content of the B element designed by the present invention is 0.001-0.006%.
A preparation method of a martensite matrix 1100 MPa-grade rare earth Q & P steel comprises the following steps:
(1) the smelting process comprises the following steps: according to the component formula provided by the invention, the materials are mixed, smelted by a converter, secondarily refined by a vacuum furnace and continuously cast to obtain a casting blank, and the casting blank comprises the following chemical components in percentage by weight: c: 0.15 to 0.22%, Si: 0.60 to 1.70%, Mn: 1.10-2.40%, Mo: 0.1-0.5%, Al: 0.1-0.5%, P: 0.02-0.04%, S is less than or equal to 0.005%, N is less than or equal to 0.0060%, and the balance of Fe and inevitable impurities;
(2) and (3) melting in a trace element process: adding trace alloy element powder into an electric arc melting furnace to obtain a secondary casting blank, wherein the casting blank comprises the following chemical components in percentage by weight: c: 0.15 to 0.22%, Si: 0.60 to 1.70%, Mn: 1.10-2.40%, Mo: 0.1-0.5%, Al: 0.1-0.5%, V: 0.05-0.11%, Y: 0.01-0.05%, P: 0.02-0.04%, S is less than or equal to 0.005%, Nb: 0.040-0.0700%, N is less than or equal to 0.0060%, B: 0.001-0.006% of Fe and inevitable impurities as the rest;
(3) hot rolling process: heating a casting blank to 1100-1150 ℃ by using a heating furnace, preserving heat for a period of time, then carrying out hot rolling, and then carrying out water quenching to room temperature;
(4) a cold rolling process, namely carrying out multi-pass cold rolling after acid pickling to obtain a steel plate with the target thickness;
(5) two-phase manganese partitioning process by heating the material to AC3And AC1(two-phase zone) keeping the temperature for a period of time, and then quenching the mixture to room temperature;
(6) one-step carbon distribution process, namely, putting the material in MSAnd MfAt a certain temperature T between0Preserving the heat for a period of time, and then quenching the material to room temperature;
(7) secondary carbon distribution process, namely, the material is added into MSAnd MfA certain temperature therebetweenDegree T1(T1Temperature ratio T0Slightly lower) for a period of time, and then water-quenching the material to room temperature.
In the preparation method of the martensite matrix 1100MPa grade rare earth Q & P steel, a continuous casting process is adopted in the casting process in the step (1);
in the step (2) of the preparation method of the martensite matrix 1100MPa grade rare earth Q & P steel, the main components of the alloy powder are Mo, Al, V, Y, Nb, N and B;
in the step (3) of the preparation method of the 1100 MPa-level martensite matrix rare earth Q & P steel, the finish rolling temperature is 820-880 ℃, the coiling temperature is 550-650 ℃, and the thickness of the obtained steel plate is 1.8-2.0 mm;
the thickness of the steel plate obtained by cold rolling in the step (4) of the preparation method of the 1100 MPa-grade rare earth Q & P steel with the martensite matrix is 1.2-1.5mm, and preferably, the pickling step is as follows: the first step of acid washing → water washing → the second step of acid washing → water washing → the next step of process;
the martensite matrix is 1100MPa grade rare earth Q&Step (5) of the P steel production methodC3And AC1Derived from the thermoexperimenter and taking errors into account;
the cooling rate in the steps (5), (6) and (7) of the preparation method of the 1100 MPa-grade rare earth Q & P steel with the martensite matrix is determined by a static CCT curve (expansion amount-temperature curve) measured by a thermal expansion meter, and the critical cooling rate of martensite phase transformation can be obtained through the static CCT curve;
in the preparation method of the 1100 MPa-grade martensite matrix rare earth Q & P steel, the heat preservation is carried out for a period of 10-300s in the steps (6) and (7).
The invention has the following beneficial effects:
(1) in the hot-rolled quenching state, the Q & P process is directly carried out after cold rolling, but not generally, complete annealing is carried out firstly to obtain a pearlite-based structure. One-step complete annealing is cancelled, so that on one hand, energy is saved, and on the other hand, long-time waiting of annealing cooling is avoided;
(2) a proper amount of trace alloy elements are added, so that on one hand, the grain refinement is promoted, and the comprehensive mechanical property of the steel plate is enhanced by utilizing the fine grains; on the other hand, the content of carbon and manganese elements is reduced, and the welding difficulty of the steel plate is reduced;
(3) through two martensite phase transformation processes, crystal grains are cut, the effect of crystal grain refinement is achieved, meanwhile, the distribution process of C elements is promoted, and the stability of residual austenite is strengthened;
(4) by adopting a continuous casting process, the cooling speed is high, and continuous casting and casting conditions are controllable and stable, so that the casting blank has uniform and compact internal structure, less segregation and stable performance;
(5) the carbon is distributed twice, so that the carbon element is sufficiently utilized, the residual austenite is sufficiently stabilized, and good comprehensive mechanical properties are obtained.
Drawings
FIG. 1 is a flow chart of the heat treatment process of the present invention.
FIG. 2 is a metallographic structure photograph of example 1 of the present invention.
In the figure, 1, smelting and casting process, 2, trace alloy element melting process, 3, heating and heat preservation process, 4, hot rolling process, 5, cold rolling process, 6, double-phase region carbon and manganese comprehensive distribution, 7, primary carbon distribution process, 8, secondary carbon distribution process, 9, AC3Line represents the end temperature of ferrite transformation to austenite upon heating, 10, AC1The line represents the temperature at which pearlite transforms to austenite on heating, 11, MfLine shows the martensite finish temperature, 12, MSThe line indicates the martensitic transformation onset temperature.
The specific implementation mode is as follows:
the following detailed description is made with reference to the accompanying drawings and examples, as shown in fig. 1-2.
The metallographic specimen in the embodiment of the invention is shot under an optical microscope to obtain a microstructure photo; the tensile test specimens are prepared according to the ASTME8 standard, and are subjected to tensile test at room temperature at a tensile rate of 1mm/min by using a WDW-100E type electronic universal tester, and the tensile strength, the elongation after fracture and the product of strength and elongation of each test specimen are obtained through testing and calculation.
Example 1
The material components and weight percentage adopted in the actual production are as follows: 0.18%, Si: 0.80%, Mn: 1.70%, Mo: 0.30%, Al: 0.20%, V: 0.05%, Y: 0.01%, P: 0.02%, S is less than or equal to 0.005%, Nb: 0.040%, N is less than or equal to 0.0060%, B: 0.001%, and the balance of Fe and inevitable impurities, and the process comprises the following steps:
(1) the smelting process comprises the following steps: according to the component formula provided by the invention, the materials are mixed, smelted by a converter, secondarily refined by a vacuum furnace and continuously cast to obtain a casting blank, and the casting blank comprises the following chemical components in percentage by weight: c: 0.18%, Si: 0.80%, Mn: 1.70%, Mo: 0.30%, Al: 0.20%, P: 0.02 percent of S, less than or equal to 0.005 percent of N, less than or equal to 0.0060 percent of N, and the balance of Fe and inevitable impurities;
(2) and (3) melting in a trace element process: adding trace alloy element powder into an electric arc melting furnace to obtain a secondary casting blank, wherein the casting blank comprises the following chemical components in percentage by weight: c: 0.18%, Si: 0.80%, Mn: 1.70%, Mo: 0.30%, Al: 0.20%, V: 0.05%, Y: 0.01%, P: 0.02%, S is less than or equal to 0.005%, Nb: 0.040%, N is less than or equal to 0.0060%, B: 0.001%, and the balance of Fe and inevitable impurities;
(3) hot rolling process: heating the casting blank to 1100 ℃ by using a heating furnace, preserving heat for 1.5 h, then carrying out hot rolling, wherein the finish rolling temperature is 860 ℃, the coiling temperature is 650 ℃, the thickness of a steel plate is 1.8mm, and then carrying out water quenching to room temperature;
(4) in the cold rolling process, after acid washing, six-pass cold rolling is carried out to obtain a steel plate with the target thickness of 1.2 mm;
(5) the two-phase zone manganese distribution process comprises heating the material to 770 deg.C at a rate of 10 deg.C per minute, maintaining for 200 s, and water quenching to room temperature;
(6) a first carbon distribution process, namely heating the material to 300 ℃ at the rate of 10 ℃ per minute and preserving the temperature for 120 s, and then quenching the material to room temperature;
(7) and a secondary carbon distribution process, namely heating the material to 280 ℃ at the rate of 10 ℃ per minute, preserving the temperature for 90 s, and then quenching the material to room temperature.
FIG. 2 is a metallographic structure photograph showing the structure after the treatment consisting of martensite, granular ferrite, and retained austenite. The elongation after fracture reaches 21.08 percent, the tensile strength is 1141.06 MPa, and the product of strength and elongation is 23.9 GPa percent.
Example 2
The material components and weight percentage adopted in the actual production are as follows: 0.18%, Si: 1.10%, Mn: 1.90%, Mo: 0.1%, Al: 0.18%, V: 0.05%, Y: 0.02%, P: 0.03%, S is less than or equal to 0.005%, Nb: 0.050%, N is less than or equal to 0.0060%, B: 0.001%, and the balance of Fe and inevitable impurities, and the process comprises the following steps:
(1) the smelting process comprises the following steps: according to the component formula provided by the invention, the materials are mixed, smelted by a converter, secondarily refined by a vacuum furnace and continuously cast to obtain a casting blank, and the casting blank comprises the following chemical components in percentage by weight: c: 0.18%, Si: 1.10%, Mn: 1.90%, Mo: 0.1%, Al: 0.18%, P: 0.03 percent of S, less than or equal to 0.005 percent of N, less than or equal to 0.0060 percent of N, and the balance of Fe and inevitable impurities;
(2) and (3) melting in a trace element process: adding trace alloy element powder into an electric arc melting furnace to obtain a secondary casting blank, wherein the casting blank comprises the following chemical components in percentage by weight: c: 0.18%, Si: 1.10%, Mn: 1.90%, Mo: 0.1%, Al: 0.18%, V: 0.05%, Y: 0.02%, P: 0.03%, S is less than or equal to 0.005%, Nb: 0.050%, N is less than or equal to 0.0060%, B: 0.001%, and the balance of Fe and inevitable impurities;
(3) hot rolling process: heating the casting blank to 1100 ℃ by using a heating furnace, preserving heat for 100 min, then carrying out hot rolling, wherein the finish rolling temperature is 860 ℃, the coiling temperature is 680 ℃, the thickness of the steel plate is 1.8mm, and then carrying out water quenching to room temperature;
(4) in the cold rolling process, after acid washing, six-pass cold rolling is carried out to obtain a steel plate with the target thickness of 1.2 mm;
(5) the two-phase zone manganese distribution process comprises heating the material to 780 ℃ at the rate of 10 ℃ per minute, keeping the temperature for 200 s, and then quenching the material to room temperature;
(6) a first carbon distribution process, namely heating the material to 280 ℃ at the rate of 10 ℃ per minute and preserving the temperature for 60 s, and then quenching the material to room temperature;
(7) and a secondary carbon distribution process, namely heating the material to 260 ℃ at the rate of 10 ℃ per minute, preserving the temperature for 40 s, and then quenching the material to room temperature.
The elongation after fracture reaches 20.38 percent, the tensile strength is 1180.06 MPa, and the product of strength and elongation is 24.0 GPa percent.

Claims (3)

1. A preparation method for preparing 1100 MPa-level rare earth alloy Q & P steel based on quenched martensite is characterized by comprising the following chemical components in percentage by weight: c: 0.15 to 0.22%, Si: 0.60 to 1.70%, Mn: 1.10-2.40%, Mo: 0.1-0.5%, Al: 0.1-0.5%, V: 0.05-0.11%, Y: 0.01-0.05%, P: 0.02-0.04%, S is less than or equal to 0.005%, Nb: 0.040-0.0700%, N is less than or equal to 0.0060%, B: 0.001-0.006% of Fe and inevitable impurities as the rest; the preparation method comprises the following specific steps:
(1) the smelting process comprises the following steps: according to the component formula, the materials are mixed and then smelted by a converter, secondarily refined by a vacuum furnace and cast to obtain a casting blank;
(2) and (3) melting in a trace element process: adding trace Mo, Al, V, Y, Nb, N and B alloy element powder into an electric arc smelting furnace to obtain a secondary casting blank;
(3) hot rolling process: heating the casting blank to 1100-1150 ℃ by using a heating furnace, preserving heat for 1-3h, then carrying out hot rolling, wherein the final rolling temperature is 820-880 ℃, the coiling temperature is 550-650 ℃, the thickness of the obtained steel plate is 1.5-3.0mm, and then carrying out water quenching to room temperature;
(4) and (3) cold rolling process: after acid washing, carrying out multi-pass cold rolling to obtain a steel plate with the thickness of 1.2-1.5 mm;
(5) the two-phase region manganese partitioning process: heating the material to A at 10-30 deg.C/sC3And AC1Keeping the temperature for 3-15min, and water-quenching to room temperature;
(6) a primary carbon distribution process: placing the material in MSAnd MfAt a certain temperature T between0Preserving the heat for 10-300s, and then quenching the material to room temperature;
(7) and (3) secondary carbon distribution process: placing the material in MSAnd MfIs a certain value lower than T0Temperature T of1Keeping the temperature for 10-300s, and then quenching the material to room temperature.
2. The method for preparing the 1100MPa grade rare earth alloy Q & P steel based on the quenched martensite as set forth in claim 1, wherein the method comprises the following steps: the material is water quenched to room temperature, and the cooling rate and the used cooling medium are determined by the martensite critical cooling rate of a specific formula.
3. The method for preparing the 1100MPa grade rare earth alloy Q & P steel based on the quenched martensite as set forth in claim 1, wherein the method comprises the following steps: the first carbon distribution temperature is slightly higher than the second carbon distribution temperature.
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