CN115161549A - High-tensile-strength alloy steel plate and preparation method thereof - Google Patents
High-tensile-strength alloy steel plate and preparation method thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of processing of ultrahigh-strength steel materials, and particularly relates to a high-tensile-strength alloy steel plate and a preparation method thereof. The invention provides a high tensile strength alloy steel plate with 1300MPa tensile strength by adjusting chemical components in alloy steel and adopting DQ-DP-T process, wherein the alloy steel plate comprises the following components by mass percent: c:0.18 to 0.25%, si:1.0 to 2.0%, mn:1.0 to 2.0%, cr:1.0 to 2.0%, ni:2.0 to 3.0, mo:0.5 to 1.0%, V:0 to 0.2%, al:0.1 to 0.5%, ti:0 to 0.2 percent, and the balance being Fe. The preparation method of the steel plate can realize the synchronous implementation of quenching and carbon distribution, not only ensures the quenching effect, but also can stabilize the residual austenite with sufficient content to room temperature, and greatly simplifies the production process flow, thereby ensuring that the prepared alloy steel plate has higher strength and plasticity and toughness. The high tensile strength alloy steel plate prepared by the invention is widely applied to steel for bridges, buildings and engineering structures, and has good development prospect.
Description
Technical Field
The invention belongs to the technical field of processing of ultrahigh-strength steel materials, and particularly relates to a high-tensile-strength alloy steel plate and a preparation method thereof.
Background
In recent years, with the increasing performance requirements of steel materials in the fields of bridges, buildings and heavy machinery, research on medium-thickness plates with high strength, good impact toughness and weldability is imperative.
High-strength steel has been developed into three generations, wherein, the formability and performance of the first generation advanced high-strength steel represented by DP steel and TRIP steel are poor, which limits the processing performance of parts, and in addition, although the Mn content in the second generation advanced high-strength steel such as high-manganese TRIP steel, TWIP effect strengthened steel and the like is high, the processing application is limited by the high production cost and the complex production process. Obviously, the first two generations of advanced high-strength steels cannot meet the engineering requirements, so that a third generation high-strength steel represented by Q & P (Quenching and balancing) steel is created, the microstructure of the steel at room temperature comprises thin-film austenite between lath-shaped martensite and martensite laths, the steel has good plasticity while meeting the high strength, face-centered cubic austenite is blended into martensite taking the body-centered cubic as a matrix, the solid solution strengthening effect is fully utilized, and the steel contains partial austenite, shows a TRIP effect in the deformation process, further improves the performance and has good strength and plasticity.
Chinese patent publication No. CN113604736a discloses a high-strength medium plate with yield strength of 800MPa, which is improved in yield strength, tensile strength and the like by adjusting chemical components of raw materials and adopting a TMCP process, but the improvement in product strength is still not high in the patent, and the elongation and the like of the material are not improved.
Although a great deal of research is made on the organization mechanism and process control of Q & P steel at home and abroad, some problems still exist in the aspects of Q & P steel component optimization design, organization stability control and industrial stable production.
Therefore, the 1300 MPa-grade ultrahigh-strength alloy steel plate is prepared by using a DQ-DP-T (direct queuing and Dynamic Partitioning and Tempering) process, so that the mechanical property of the alloy steel material can be further improved while the stability of the material is improved.
Disclosure of Invention
Because quenching and distribution are two independent processes in the traditional Q & P steel processing technology, both a one-step method and a two-step method need quenching to a certain specific temperature, and the problems of complex preparation technology and difficult control of technological results exist.
The invention also provides a preparation method of the high tensile strength alloy steel plate.
Based on the purpose, the invention adopts the following technical scheme:
the high-tensile-strength alloy steel plate is prepared by adopting the processes of forging, hot rolling, quenching, dynamic partitioning, tempering and the like, and comprises the following components in percentage by mass: c:0.18 to 0.25%, si:1.0 to 2.0%, mn:1.0 to 2.0%, cr:1.0 to 2.0%, ni:2.0 to 3.0, mo:0.5 to 1.0%, V:0 to 0.2%, al:0.1 to 0.5%, ti:0 to 0.2 percent, and the balance of Fe and inevitable impurities.
Further preferably, the alloy steel plate comprises the following components in percentage by mass: c:0.18 to 0.25%, si:1.0 to 1.5%, mn:1.0 to 1.5%, cr:1.0 to 1.5%, ni:2.0 to 3.0, mo:0.5 to 1.0%, V:0 to 0.1%, al:0.2 to 0.5%, ti:0 to 0.2 percent, and the balance of Fe and inevitable impurities.
The preparation method of the high tensile strength alloy steel plate comprises the following steps:
(1) Preparing an ingot: preparing materials according to the mass percent of each component in the alloy steel plate, and obtaining a round ingot by utilizing a vacuum melting process of a vacuum induction furnace, wherein the vacuum degree during vacuum melting is less than 5Pa, the impurity element S after melting is less than or equal to 0.001 wt%, and the impurity element P is less than or equal to 0.006 wt%;
(2) Casting ingot forging: keeping the temperature of the round cast ingot obtained in the step (1) at 1200-1250 ℃ for 1.5-2 h, forging, controlling the initial forging temperature to be 1230-1250 ℃, the final forging temperature to be more than 950 ℃, the forging time to be within 40min, and cooling to room temperature after forging to obtain a forging stock;
(3) Hot rolling: carrying out hot rolling on the forging stock obtained in the step (2) at the temperature of 950-1250 ℃, controlling the hot rolling time within 30min, and obtaining a steel plate with the thickness of 20-40 mm after rolling;
(4) Quenching, dynamic partitioning and tempering: cooling the alloy steel plate after hot rolling in the step (3) to room temperature in air, and carrying out quenching treatment, wherein the quenching transfer time is controlled within 15s, and the cooling rate is 0.1-5 ℃/s; then placing the mixture for 8 to 12 hours at room temperature and then tempering the mixture to obtain the final product.
Further, in the step (2), the vacuum melting process comprises the steps of charging, vacuumizing, heating, melting, alloying, stirring, casting and the like, wherein the heating and melting temperature is 1520-1600 ℃, the casting temperature is 1520-1560 ℃, and the casting time is controlled within 3 min.
Further, in the step (2), the forged forging stock is heated to 1200-1250 ℃, and the temperature is kept for 1-2h by homogenizing annealing.
Further, the hot rolling in the step (3) is carried out by adopting a two-stage controlled rolling method, and the specific steps are that the forging stock obtained in the step (2) is firstly rolled at 1200-1250 ℃, then is finally rolled at 950-1000 ℃, and the hot rolling time is controlled within 30 min.
Furthermore, the two-stage controlled rolling method is adopted in the step (3) for hot rolling, the total reduction deformation amount can be 40-80%, and the mechanical property of the plate can be improved by controlling the deformation amount.
Further, in the step (4), with the temperature reduction in the air cooling process, the alloy steel plate successively passes through the martensite transformation start temperature Ms and the martensite transformation end temperature Mf, that is, passes through the martensite transformation temperature range (Ms-Mf temperature range), so as to complete the transformation of martensite and the carbon distribution, and when passing through the martensite transformation temperature range, the cooling rate is 0.1-5 ℃/s, specifically, the martensite transformation start temperature Ms is 394-386 ℃, and the martensite transformation end temperature Mf is 164-176 ℃.
Further, the specific step of the tempering treatment in the step (4) is that the mixture is heated to 400-450 ℃ at the speed of 10-15 ℃/min, and then is air-cooled to the room temperature after heat preservation for 1-2 h.
Furthermore, the steel plate with the thickness of 20-40 mm is prepared by the processes of forging, hot rolling, quenching, dynamic partitioning, tempering and the like, and the room-temperature structure consists of ferrite, a lath-shaped martensite matrix, film-shaped retained austenite, a small amount of island-shaped retained austenite and carbide, wherein the content of the retained austenite is 3-15%, and the content of carbon in the retained austenite is 0.7-1.5%.
Furthermore, the stability of the retained austenite of the high-tensile-strength alloy steel plate prepared by the invention is not only influenced by chemical components, but also closely related to the shape and the size, original austenite grains can be effectively refined by adopting a DQ-DP-T process, and the subsequent C distribution process is facilitated, so that the C distribution of the test steel can still be realized under the condition of lower carbon content, and in the slow cooling process, when the cooling rate is low, the C distribution time is correspondingly prolonged, the enrichment of C in the retained austenite is facilitated, and the stability of the retained austenite at room temperature is increased.
Specifically, fig. 1 is a schematic diagram of a heat treatment process when the alloy steel plate of the present invention successively passes through a martensite transformation start temperature Ms and a martensite transformation end temperature Mf along with a temperature decrease in an air cooling process, just as in the above preparation method of the high tensile strength alloy steel plate, the heat treatment of the present invention includes a process of heating to achieve complete austenitization after smelting, casting and forging, a process of hot rolling at 950-1250 ℃, a process of quenching and dynamic partitioning in a process of air cooling after hot rolling, and several processes of heating the steel plate to 400-450 ℃ after air cooling, tempering for 1-2h, and further enhancing the partitioning effect and increasing the austenite content.
Compared with the traditional Q & P process, the quenching and distribution processes of the DQ-DP-T process are synchronously carried out, so that the quenching effect is ensured, the residual austenite with sufficient content can be stabilized to room temperature, and the room-temperature structure of martensite and residual austenite can be obtained without a complex isothermal control process, thereby ensuring high strength and high plasticity.
And then tempering is carried out, the martensite part is reversed to be changed into austenite while carbide is precipitated, the content of residual austenite at room temperature is increased, the plasticity is further improved, and the precipitation strengthening effect of carbide formed by micro alloy elements such as Mo, V and the like is fully utilized, so that stable alloy carbide can be dispersed and precipitated on the martensite matrix while carbon is distributed, and the tensile strength is further improved.
And because the contents of C and Si are lower, the steel has good weldability while ensuring good strength and plasticity. The final yield strength is 1100-1400 MPa, the tensile strength is 1300-1600 MPa, the elongation is 14-20%, and the product of strength and elongation is 20-30 GPa.
Compared with the traditional Q & P production process, the invention fully utilizes the waste heat after rolling to carry out dynamic distribution, thereby saving a large amount of energy. And by tempering, the comprehensive performance is improved, the production cost is reduced, and the performance is excellent, so that the application prospect is good.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention mainly aims to solve the problems of complex process and high cost in the production process of the current Q & P steel, and utilizes DQ-DP-T (direct Quenching and Dynamic Partitioning and Tempering) process to complete Quenching and Dynamic Partitioning simultaneously in the process of air cooling to room temperature, thereby simplifying the production process, slowly passing through an Ms-Mf transformation zone during air cooling to complete martensite transformation and carbon Partitioning, then partially reversing martensite to generate austenite through Tempering, further increasing the content of residual austenite at room temperature, and improving the mechanical property.
2. The quenching process is air cooling and quenching to room temperature, compared with the traditional Q & P steel quenching to a certain temperature ranging from Ms to Mf, the control difficulty is reduced, the isothermal process is simplified, and the production cost is reduced. The process method of the invention does not need quenching to a specific quenching temperature and a partitioning isothermal temperature, and can obtain the steel with excellent performance higher than that of the traditional Q & P production process only by tempering after direct quenching-dynamic partitioning, thereby saving the production cost and having wide application prospect.
3. According to the invention, by controlling the contents of alloy elements such as C, si and the like, the steel is ensured to have good weldability while the direct quenching-dynamic partitioning-tempering effect is ensured.
4. According to the invention, elements such as Si, al and the like which inhibit carbide precipitation are added to inhibit carbide precipitation, so that quenching and dynamic partitioning are ensured to be carried out simultaneously, then martensite is reversely transformed through tempering, a small amount of carbide is precipitated simultaneously, and high strength and high plasticity are ensured; the final properties are then improved by about 20% by tempering.
Drawings
FIG. 1 is a schematic view of a heat treatment process of an alloy steel plate of the invention when the alloy steel plate successively passes a martensite start temperature Ms and a martensite finish temperature Mf along with temperature reduction in an air cooling process;
FIG. 2 is a photograph comparing an alloy steel sheet according to example 1 of the present invention with that of comparative example 1;
FIG. 3 is an XRD pattern of example 1 of the present invention and comparative example 1;
FIG. 4 is a microstructure diagram of example 1 and comparative example 1 according to the present invention, the left image being example 1 and the right image being comparative example 1;
FIG. 5 is a stress-strain graph of example 1 of the present invention and comparative example 1;
FIG. 6 is an XRD pattern of example 2 of the present invention and comparative example 2;
FIG. 7 is a microstructure diagram of example 2 of the present invention and comparative example 2, the left drawing being example 2 and the right drawing being comparative example 2;
fig. 8 is a stress-strain graph of inventive example 2 and comparative example 2.
Detailed Description
In order to make the technical purpose, technical scheme and beneficial effects of the invention clearer, the technical scheme of the invention is further described with reference to specific examples, which are intended to explain the invention and are not to be construed as limiting the invention, and the specific techniques or conditions are not indicated in the examples, which are performed according to the techniques or conditions described in the literature in the field or according to the product specification, and the raw materials used in the following examples are all common commercial products.
Example 1
A high-tensile-strength alloy steel plate with 1300MPa of tensile strength is prepared by the processes of forging, hot rolling, quenching, dynamic partitioning, tempering and the like of an alloy cast ingot, and comprises the following chemical components in percentage by mass: c:0.21%, si:1.0%, mn:1.2%, cr:1.2%, ni:3.2%, mo:0.6%, V:0.08%, al:0.2%, ti:0.02%, and the balance of Fe and inevitable impurities.
The preparation method of the high tensile strength alloy steel plate comprises the following specific steps:
(1) Preparing an ingot: the method comprises the following steps of proportioning according to the mass percent of each component in the alloy steel plate, obtaining a round cast ingot by utilizing a vacuum melting process of a vacuum induction furnace, wherein the vacuum melting process comprises the steps of charging, vacuumizing, heating, melting, alloying, stirring, casting and the like, wherein the melting temperature is 1520 ℃, the casting time is controlled within 3min, the vacuum degree during vacuum melting is less than 5Pa, the impurity element S after melting is less than or equal to 0.001 wt%, and the P is less than or equal to 0.006 wt%, and the specific operation steps of vacuum melting can be realized by adopting a common method in the prior art, are not the invention points of the invention, and are not described again;
(2) Casting ingot forging: keeping the temperature of the round cast ingot obtained in the step (1) at 1200 ℃ for 1.5h, then freely forging, controlling the initial forging temperature to be 1230 ℃, the final forging temperature to be more than 950 ℃, controlling the forging time to be within 40min, cooling to room temperature after forging to obtain a forging stock, then heating the forging stock to 1250 ℃, and carrying out homogenization annealing and heat preservation for 2h;
(3) Hot rolling: carrying out hot rolling on the forged blank subjected to annealing treatment in the step (2) by adopting a two-stage controlled rolling method, firstly carrying out initial rolling and then carrying out final rolling, wherein the initial rolling temperature is 1250 ℃, the final rolling temperature is 950 ℃, the rolling time is controlled within 30min, and a steel plate with the thickness of 40mm is obtained after the final rolling;
(4) Quenching, dynamic partitioning and tempering: air-cooling the steel plate after hot rolling in the step (3) to room temperature for quenching treatment, wherein the quenching transfer time is controlled within 15s, the alloy steel plate successively passes through a martensite transformation starting temperature Ms and a martensite transformation ending temperature Mf along with the temperature reduction in the air-cooling process, namely passes through a martensite transformation temperature interval (Ms-Mf temperature interval), the transformation of martensite and the distribution of carbon are completed, and when the alloy steel plate passes through the martensite transformation temperature interval, the cooling rate is 0.1 ℃/s, specifically, ms in the embodiment is 394 ℃, and Mf is 164 ℃; and then placing the mixture at room temperature for 12h and then tempering, wherein the tempering comprises the specific steps of heating to 400 ℃ at the speed of 10 ℃/min, preserving heat for 1h, and then air-cooling to room temperature to obtain the final product.
The final product specification of example 1 was 600X 200X 40mm (length X width X height) as shown in FIG. 2.
According to the national standard GB/T228.1-2010, the steel plate prepared by the embodiment is detected to have the yield strength of 1160-1200 MPa, the tensile strength of 1375-1410 MPa, the elongation of 18.0-19.0% and the product of strength and elongation of 24-27 GPa.
Comparative example 1
Comparative example 1 the raw material of the chemical composition of example 1 was prepared by the prior art DQ-DP process without tempering. Photographs of the product of example 1 and the product of comparative example 1 are shown in fig. 2.
The results of performance tests of the product obtained in comparative example 1 without tempering and the product obtained in example 1 after tempering are shown in fig. 3, 4 and 5, wherein fig. 3 is an XRD chart of example 1 and comparative example 1, and it can be seen from the XRD analysis result of fig. 3 that the residual austenite content after tempering in example 1 is about 6%, and the higher residual austenite content is a main reason for the excellent plasticity of example 1. As shown in fig. 4, it can be seen from fig. 4 that the martensite laths before tempering have a relatively coarse microstructure, thin film (strip) retained austenite is present between the coarse laths, the microstructure after tempering is still a martensite lath and thin film or block retained austenite located between the laths, the martensite laths are refined to some extent, and the proportion of the thin film retained austenite tends to increase after tempering. The stress-strain curves of the product of example 1 and the product of comparative example 1 are shown in fig. 5, and it can be seen from fig. 5 that the elongation after tempering is greatly improved.
Compared with the comparative example 1, the embodiment 1 adds the tempering auxiliary distribution process on the basis of the comparative example 1, effectively enhances the diffusion effect of the C element from the martensite to the austenite, promotes the martensite to generate partial reverse transformation, improves the austenite content and improves the elongation of the steel plate. After the finally prepared steel plate is tempered, the elongation is improved by about 4-5%, and the product of strength and elongation is improved by about 25%, so that the steel plate has better comprehensive mechanical properties.
The results of comparing the mechanical properties of example 1 with those of comparative example 1 are shown in Table 1.
TABLE 1
As can be seen from table 1, after quenching treatment, carbon is distributed reasonably, and in example 1, the austenite content of the steel is increased, and although the strength is slightly reduced, the elongation is improved significantly, and the product of strength and elongation is increased by about 15%.
As can be seen from fig. 3, 4, 5 and table 1, in example 1, after the tempering treatment, the yield strength of the steel is significantly increased, the tensile strength is slightly decreased, and the elongation is significantly increased, because in the tempering process, the martensite is partially reversed to austenite, the content of the retained austenite stably existing at room temperature is increased, a small portion of carbide is precipitated, and the plasticity and yield strength of the material are greatly improved, and the product of strength and elongation is significantly increased in the case of slightly decreased tensile strength. Compared with the prior art and the subsequent art in the example 1, the comprehensive performance of the material is improved by about 19 percent, and a good performance effect is obtained.
Example 2
A high-tensile-strength alloy steel plate with 1300MPa of tensile strength is prepared by utilizing the processes of forging, hot rolling, quenching, dynamic partitioning, tempering and the like to prepare an alloy ingot, and comprises the following chemical components in percentage by mass: c:0.25%, si:1.0%, mn:1.2%, cr:1.2%, ni:2.6%, mo:0.6%, V:0.08%, al:0.2%, ti:0.02%, and the balance of Fe and inevitable impurities.
The preparation method of the high tensile strength alloy steel plate comprises the following specific steps:
(1) Preparing an ingot: the method comprises the following steps of proportioning according to the mass percent of each component in the alloy steel plate, obtaining a round cast ingot by utilizing a vacuum melting process of a vacuum induction furnace, wherein the vacuum melting process comprises the steps of charging, vacuumizing, heating, melting, alloying, stirring, casting and the like, wherein the melting temperature is 1600 ℃, the casting temperature is 1560 ℃, the casting time is controlled within 3min, the vacuum degree during vacuum melting is less than 5Pa, the impurity elements S after melting is less than or equal to 0.001 wt%, and P is less than or equal to 0.006 wt%, and the specific operation steps of vacuum melting can be realized by adopting a common method in the prior art, are not the invention points of the invention and are not repeated;
(2) Casting ingot forging: preserving heat of the round cast ingot obtained in the step (1) at 1250 ℃ for 2h, freely forging, controlling the initial forging temperature to 1250 ℃, the final forging temperature to be higher than 950 ℃, controlling the forging time to be within 40min, cooling to room temperature after forging to obtain a forging blank, heating the forging blank to 1250 ℃, homogenizing, annealing and preserving heat for 2h;
(3) Hot rolling: carrying out hot rolling on the forged blank subjected to annealing treatment in the step (2) by adopting a two-stage controlled rolling method, firstly carrying out initial rolling and then carrying out final rolling, wherein the initial rolling temperature is 1200 ℃, the final rolling temperature is 1000 ℃, the rolling time is controlled within 30min, and a steel plate with the thickness of 30mm is obtained after the final rolling;
(4) Quenching, dynamic partitioning and tempering: air-cooling the steel plate after hot rolling in the step (3) to room temperature for quenching treatment, wherein the quenching transfer time is controlled within 15s, the alloy steel plate successively passes through a martensite transformation starting temperature Ms and a martensite transformation ending temperature Mf along with the reduction of the temperature in the air-cooling process, namely passes through a martensite transformation temperature interval (Ms-Mf temperature interval), the transformation of martensite and the distribution of carbon are completed, and when the alloy steel plate passes through the martensite transformation temperature interval, the cooling rate is 0.2 ℃/s, specifically, ms in the embodiment is 386 ℃, and Mf is 176 ℃; and then placing the mixture at room temperature for 12h and then tempering, wherein the tempering comprises the specific steps of heating to 450 ℃ at the speed of 15 ℃/min, preserving heat for 1h, and then air-cooling to room temperature to obtain the final product.
According to the steel plate prepared by the embodiment, according to the national standard GB/T228.1-2010, the yield strength is 1200-1250 MPa, the tensile strength is 1450-1500 MPa, the elongation is 18.0-19.0%, and the product of strength and elongation is 26.0-28.0 GPa%.
Comparative example 2
Comparative example 2 the starting material for the chemical composition of example 2 was prepared using the prior art DQ-DP process and was not tempered.
The performance test of the product obtained in comparative example 1 without tempering and the product obtained in example 1 after tempering showed that the XRD patterns of example 2 and comparative example 2 are shown in fig. 6, 7 and 8, and the XRD analysis result of fig. 6 shows that the content of the retained austenite after tempering is about 5.8%, which indicates that the content of the retained austenite in example 2 is also relatively high, and the relatively high content of the retained austenite is also the main reason for the excellent plasticity of example 2. The microstructure of the product of example 2 and that of the product of comparative example 2 are shown in FIG. 7, and it can be seen that the tempered structure is mainly composed of martensite laths and thin-film or bulk retained austenite located between the laths, and the proportion of dot-like or thin-film retained austenite phase is increased after tempering. The stress-strain curves of the product of example 2 and the product of comparative example 2 are shown in fig. 8, and it can be seen in fig. 8 that the elongation after tempering is greatly improved.
The results of comparing the mechanical properties of example 2 with those of comparative example 2 are shown in Table 2.
TABLE 2
As can be seen from Table 1, after quenching treatment, carbon is reasonably distributed, the austenite content of the steel in example 2 is also increased to some extent, the elongation is increased by about 6%, and the product of strength and elongation is increased by about 24%.
As can be seen from fig. 6, 7, 8 and table 2, in comparative example 2, the elongation of the material is poor and the yield strength is low without tempering treatment, and in example 2, the tensile strength of the steel is slightly decreased after tempering treatment, but the yield strength and elongation are significantly increased because the martensite is partially reversed to austenite during tempering, the content of the residual austenite stably existing at room temperature is increased, a small portion of carbide is precipitated, and in the case of slightly decreasing the tensile strength, the plasticity and yield strength of the material are significantly improved, and the product of strength and elongation are significantly increased. Compared with the materials before and after tempering in the example 2, the comprehensive performance of the material is improved by about 22 percent, and good performance effect is also obtained.
The steel plate can realize the synchronous quenching and carbon distribution without accurately controlling quenching stopping temperature or online heating and heat preservation equipment in the production process, thereby not only ensuring the quenching effect, but also stabilizing the residual austenite with sufficient content to room temperature, and obtaining the room temperature structure of martensite and residual austenite without a complex isothermal control process.
While specific embodiments of the present invention have been described above, it should be understood that the present invention is not limited to the specific embodiments described above. Various changes or modifications may be made by those skilled in the art within the scope of the claims without departing from the spirit of the invention.
Claims (8)
1. The high-tensile-strength alloy steel plate is characterized by comprising the following components in percentage by mass: c:0.18 to 0.25%, si:1.0 to 2.0%, mn:1.0 to 2.0%, cr:1.0 to 2.0%, ni:2.0 to 3.0, mo:0.5 to 1.0%, V:0 to 0.2%, al:0.1 to 0.5%, ti:0 to 0.2 percent, and the balance being Fe.
2. The high tensile strength alloy steel plate of claim 1, wherein the alloy steel plate comprises the following components in percentage by mass: c:0.18 to 0.25%, si:1.0 to 1.5%, mn:1.0 to 1.5%, cr:1.0 to 1.5%, ni:2.0 to 3.0, mo:0.5 to 1.0%, V:0 to 0.1%, al:0.2 to 0.5%, ti:0 to 0.2 percent, and the balance being Fe.
3. A method for manufacturing a high tensile strength alloy steel sheet according to claim 1 or 2, comprising the steps of:
(1) Preparing an ingot: preparing materials according to the mass percentage of each component in the alloy steel plate, and obtaining an ingot by using a vacuum melting process, wherein the vacuum degree is less than 5Pa;
(2) Casting ingot forging: keeping the temperature of the cast ingot obtained in the step (1) at 1200-1250 ℃ for 1.5-2h, forging, controlling the initial forging temperature at 1230-1250 ℃, the final forging temperature at more than 950 ℃ and the forging time within 40min, and cooling to room temperature after forging to obtain a forging blank;
(3) Hot rolling: carrying out hot rolling on the forging stock obtained in the step (2) at the temperature of 950-1250 ℃, controlling the hot rolling time within 30min, and obtaining a steel plate with the thickness of 20-40mm after rolling;
(4) Quenching, dynamic partitioning and tempering: cooling the alloy steel plate hot rolled in the step (3) to room temperature in air, and carrying out quenching treatment, wherein the quenching transfer time is controlled within 15s, and the cooling rate is 0.1-5 ℃/s; and then placing the mixture at room temperature for 8-12h and then tempering to obtain a final product.
4. The preparation method according to claim 3, characterized in that in the step (2), the forged blank is heated to 1200-1250 ℃, and then is subjected to homogenizing annealing and heat preservation for 1-2h.
5. The preparation method according to claim 3, characterized in that the hot rolling in the step (3) is carried out by a two-stage controlled rolling method, and the specific steps are that the forging stock obtained in the step (2) is firstly rolled at 1200-1250 ℃, then is finally rolled at 950-1000 ℃, and the hot rolling time is controlled within 30 min.
6. The production method according to claim 3, wherein in the step (4), the alloy steel sheet passes the martensite start temperature Ms and the martensite finish temperature Mf in sequence with a decrease in temperature during the air cooling.
7. The method of claim 6, wherein the martensitic transformation start temperature Ms is 394 ℃ to 386 ℃ and the martensitic transformation end temperature Mf is 164 ℃ to 176 ℃.
8. The preparation method according to claim 3, wherein the tempering in the step (4) comprises heating at a rate of 10 to 15 ℃/min to 400 to 450 ℃, keeping the temperature for 1 to 2 hours, and then cooling in air to room temperature.
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