Method for producing low-carbon alloy steel, low-carbon alloy steel

Abstract

The application relates to a preparation method of a low-carbon alloy steel, which comprises the following steps: carrying out converter steelmaking to obtain molten steel, adding aluminum into the molten steel for deoxidization; introducing the deoxidized molten steel into an LF furnace, blowing argon for refining to obtain refined molten steel; adding manganese iron deoxidizer into the refined molten steel for deoxidization and vanadium-nitrogen alloying; vacuum treating the alloyed molten steel, then carrying out casting and preparing into a steel billet; carrying out rough rolling, finish rolling and coiling of the steel billet to obtain a steel coil; carrying out uncoiling and straightening of the steel coil after cooling, and cutting into a preformed steel plate; carrying out solid solution treatment of the preformed steel plate, the temperature of the solid solution treatment is 900-930 DEG C, the preformed steel plate is cooled after the solid solution treatment, the cooling rate is 50-80 DEG C / s, and a post-solid-solution steel plate is obtained; the post-solid-solution steel plate is aged at 60-80 DEG C for 3-12 h, and then naturally cooled to obtain the low-carbon alloy steel. The application can effectively improve the strength of the low-carbon alloy steel, and meanwhile ensures that the low-carbon alloy steel has excellent low-temperature toughness.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of steel industry, and in particular to low carbon steel. BACKGROUND

[0002] Low carbon alloy steel with yield strength of 350 MPa or more is widely used in bridge, energy, building, ship and other engineering structures due to its small amount of alloy addition, simple production process and large market demand. Low carbon alloy steel is often treated by aging method. The steel is rapidly cooled from high temperature to room temperature to obtain a single-phase supersaturated solid solution. The organization (mainly martensite and residual austenite) and internal stress are unstable. At room temperature or a certain high temperature, the solute atoms in the supersaturated solid solution still have a certain diffusion capacity. With the extension of time, the solute elements will be desolvated (or precipitated), and the system will change from a non-equilibrium state to an equilibrium state, thereby changing the performance of the steel, i.e. aging. The conditions for artificial aging must be met: the solute elements in the solid solution should have a certain solid solubility and decrease with the decrease of temperature; the solute elements are in a supersaturated state after high-temperature solid solution treatment; at a lower temperature, the solute atoms still have a certain diffusion capacity. After artificial aging, the steel often shows the phenomenon of increased strength and hardness and decreased plasticity and toughness. This often leads to poor strength-toughness matching of low carbon alloy steel treated by aging, and the further expansion of the application range is limited. SUMMARY

[0003] Embodiments of the present application provide a preparation method of low carbon alloy steel and low carbon alloy steel to solve the technical problem of poor strength-toughness matching of low carbon alloy steel.

[0004] In a first aspect, embodiments of the present application provide a preparation method of low carbon alloy steel, which comprises the following steps:

[0005] Performing converter steelmaking to obtain molten steel, and adding aluminum to the molten steel for deoxidization;

[0006] Introducing the deoxidized molten steel into an LF furnace, blowing argon for refining to obtain refined molten steel;

[0007] Adding manganese iron deoxidizer to the refined molten steel for deoxidization and performing vanadium-nitrogen alloying;

[0008] Performing vacuum treatment on the alloyed molten steel, then casting and preparing into a billet;

[0009] Performing rough rolling, finish rolling and coiling on the billet to obtain a steel coil;

[0010] Uncoiling and straightening the steel coil after cooling, and cutting into a preformed steel plate;

[0011] The preformed steel plate is subjected to solid solution treatment, the temperature of the solid solution treatment is 900-930℃, the preformed steel plate is cooled after the solid solution treatment, the cooling rate is 50-80℃ / s, and a steel plate after solid solution treatment is obtained;

[0012] The steel plate after solid solution treatment is subjected to aging treatment at 60-80℃ for 3-12h, and then is naturally cooled, and the low-carbon alloy steel is obtained.

[0013] In some embodiments of the present application, the deoxidation and alloying are performed when the tapping progress of the LF furnace is 1 / 3, and the tapping progress is completed before 2 / 3.

[0014] In some embodiments of the present application, the temperature of the tapping of the LF furnace is not lower than 1680℃; and / or,

[0015] The time of the tapping of the LF furnace is 2.5-6min.

[0016] In some embodiments of the present application, the billet is heated to 1200-1260℃ before rough rolling; and / or,

[0017] The heating rate is 9-15min / cm.

[0018] In some embodiments of the present application, the rough rolling temperature is 1060-1180℃; and / or,

[0019] The first-pass reduction rate of the rough rolling is greater than 15%; and / or,

[0020] The thickness of the rough rolling process steel plate outlet is 3.5-10.5 times the thickness of the low-carbon alloy steel.

[0021] In some embodiments of the present application, the cumulative reduction rate of the finish rolling is not less than 70%; and / or,

[0022] The cumulative reduction rate of the last pass is not less than 40%; and / or,

[0023] The finish rolling temperature is 860-890℃.

[0024] In some embodiments of the present application, the coiling temperature is 560-600℃.

[0025] In the second aspect, the embodiments of the present application provide a low-carbon alloy steel, which is the low-carbon alloy steel prepared by any one of the embodiments of the first aspect.

[0026] In some embodiments of the present application, the low-carbon alloy steel comprises the following components in terms of mass percentage:

[0027] C: 0-0.03%,

[0028] Si: 0-0.2%,

[0029] Mn: 0.80-2.00%,

[0030] P: 0-0.008%,

[0031] S: 0-0.003%,

[0032] N: 0-0.03%,

[0033] Al: 0-0.035%,

[0034] V: 0-0.3%.

[0035] In some embodiments of the present application, the low-carbon alloy steel has a room-temperature yield strength of 480 MPa or more, a tensile strength of 550-675 MPa, an elongation of 18% or more, and a low-temperature impact toughness of 80 J or more at -20°C.

[0036] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages:

[0037] The low-carbon alloy steel provided by the embodiments of the present application has a low carbon content and appropriate V and N strengthening elements, and Al and Mn elements are introduced, which can effectively improve the comprehensive performance and aging treatment effect of the steel and is conducive to ensuring the low-temperature toughness of the steel; through solid solution treatment and aging heat treatment process, the low-carbon steel precipitation strengthening principle is fully utilized, and the carbides in the low-carbon steel are precipitated by keeping at a relatively low temperature, which effectively improves the strength of the low-carbon alloy steel and ensures its excellent low-temperature toughness, thereby expanding the application range of the low-carbon alloy steel. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and serve to explain the principles of the present application together with the specification.

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings from these drawings without any creative effort.

[0040] Figure 1 The metallographic structure diagram of the low-carbon alloy steel provided by Embodiment 1 of the present application. DETAILED DESCRIPTION

[0041] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0042] Unless otherwise specifically indicated, the terms used in the present application are to be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. If there is a conflict between the present description and the specification, the present description takes precedence.

[0043] Unless otherwise specifically indicated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0044] The existing low-carbon alloy steel has the technical problem of poor matching of strength and toughness.

[0045] The technical solutions provided by the embodiments of the present application are to solve the above technical problems, and the general idea is as follows:

[0046] In a first aspect, the embodiments of the present application provide a preparation method of a low-carbon alloy steel, and the method comprises the following steps:

[0047] S1: obtaining molten steel by converter steelmaking, and adding aluminum to the molten steel for deoxidation;

[0048] S2: introducing the deoxidized molten steel into an LF furnace, blowing argon for refining, and obtaining refined molten steel;

[0049] S3: adding manganese iron deoxidizer to the refined molten steel for deoxidation, and performing vanadium-nitrogen alloying;

[0050] S4: vacuum treatment of the alloyed molten steel, then casting, and preparing into a billet;

[0051] S5: rough rolling, finish rolling and coiling of the billet to obtain a steel coil;

[0052] S6: uncoiling and straightening after the steel coil is cooled, and cutting into a preformed steel plate;

[0053] S7: solid solution treatment of the preformed steel plate, the temperature of the solid solution treatment is 900-930℃, the preformed steel plate is cooled after the solid solution treatment, and the cooling rate is 50-80℃ / s, to obtain a solid-solution-treated steel plate;

[0054] S8: aging treatment of the solid-solutioned steel plate at 60-80 DEG C for 3-12h, and then natural cooling to obtain the low-carbon alloy steel.

[0055] The steps S1 and S3 introduce Al, Mn, V, N and other elements into the low-carbon alloy steel.

[0056] Al is a common deoxidizer in steel, which fixes free nitrogen in steel, increases grain coarsening temperature of the steel, reduces brittle transition temperature of the steel, prevents strain and temperature aging, and improves impact toughness of the steel.

[0057] Mn has solid solution strengthening effect, which can increase hardness and strength of the steel without affecting ductility of the steel. Mn is also a forming element of austenite, and after a large amount of Mn is added, residual austenite structure can be obtained, quenching temperature and hardness of the steel are reduced, and quenching deformation is reduced.

[0058] V produces fine-grain strengthening and significant precipitation strengthening effect in the steel, V4C3 precipitates are produced, carbon and nitrogen solubility in ferrite and diffusion speed of carbon and nitrogen atoms are affected, and thus aging strengthening effect is indirectly affected.

[0059] N is similar to carbon in properties, and is a basic element causing aging. N combines with Al to form AlN, and can be completely melted into austenite at a high temperature. AlN is precipitated in the aging process, and has strengthening effect.

[0060] The step S3 of the application adopts low-carbon ferromanganese and vanadium-nitrogen alloying, which can reduce end-point molten steel over-oxidation phenomenon, and reduce oxide inclusion content and grade in the steel.

[0061] The solid solution treatment is carried out under the conditions in the step S8, a faster cooling rate is used, and supersaturated alpha solid solution is easily obtained, stress field, dislocation zone and other lattice defects are produced, metastable phase epsilon carbide and nitride are precipitated from the inhomogeneous solid solution through aging treatment, the precipitated metastable phase and the parent phase solid solution maintain coherent relationship, and the movement of dislocations is hindered, and thus the strength is improved.

[0062] The low-carbon alloy steel provided by the application has low carbon content and appropriate V and N strengthening elements, and Al and Mn elements are introduced, which can effectively improve comprehensive performance of the steel and aging treatment effect, and is beneficial to guarantee low-temperature toughness of the steel; through solid solution treatment and aging heat treatment process, precipitation strengthening principle of the low-carbon steel is fully utilized, carbides in the low-carbon steel are precipitated by keeping at a low temperature, the strength of the low-carbon alloy steel is effectively improved, excellent low-temperature toughness of the low-carbon alloy steel is ensured, and the application range of the low-carbon alloy steel can be expanded.

[0063] In addition, the process parameters of the application are easy to control, economic benefits are high, and the application is suitable for large-scale production.

[0064] In some embodiments of the present application, the deoxidation and alloying are performed when the tapping progress of the LF furnace is 1 / 3, and the tapping progress is completed before 2 / 3.

[0065] The beneficial effect of the deoxidation and alloying performed in the above stage is that the deoxidation can effectively improve the purity of the molten steel, reduce the number of inclusions, and change the distribution state thereof, and through the addition of vanadium-nitrogen alloy, on the one hand, the liquidus temperature of the molten steel is effectively reduced, and on the other hand, the strength of the steel is improved.

[0066] In some embodiments of the present application, the temperature of the tapping of the LF furnace is not lower than 1680℃; and / or,

[0067] The time of the tapping of the LF furnace is 2.5-6 min.

[0068] In some embodiments of the present application, the billet is heated to 1200-1260℃ before rough rolling; and / or,

[0069] The heating rate is 9-15 min / cm.

[0070] The beneficial effect of the heating of the billet to 1200-1260℃ before rough rolling is that the raw material is usually heated to the austenite single-phase solid solution temperature range, and has a high temperature and sufficient time to homogenize the structure and dissolve carbides, so as to obtain a metal structure with high plasticity, low deformation resistance, and good workability.

[0071] In some embodiments of the present application, the rough rolling opening temperature is 1060-1180℃; and / or,

[0072] The rough rolling first pass reduction is greater than 15%; and / or,

[0073] The rough rolling process steel plate outlet thickness is 3.5-10.5 times the thickness of the low-carbon alloy steel.

[0074] The first pass reduction of the rough rolling is large, which is beneficial to eliminate or reduce the banded structure.

[0075] In some embodiments of the present application, the cumulative reduction of the finish rolling is not less than 70%; and / or,

[0076] The final pass cumulative reduction is not less than 40%; and / or,

[0077] The finish rolling final rolling temperature is 860-890℃.

[0078] In some embodiments of the present application, the coiling temperature is 560-600℃.

[0079] In a second aspect, the embodiments of the present application provide a low-carbon alloy steel, which is prepared by the low-carbon alloy steel of any one of the first aspect.

[0080] In some embodiments of the present application, the low-carbon alloy steel comprises the following components in mass percentage:

[0081] C: 0-0.03%,

[0082] Si: 0-0.2%,

[0083] Mn: 0.80%-2.00%,

[0084] P: 0-0.008%,

[0085] S: 0-0.003%,

[0086] N: 0-0.03%,

[0087] Al: 0-0.035%,

[0088] V: 0-0.3%.

[0089] The element C is one of the indispensable elements in steel materials, and the content of C in steel largely determines the performance of the material. In the solid solution stage, part of the carbon element in the steel will be dissolved into the matrix of the steel to play a solid solution strengthening role; part of the carbon will form carbides with other alloying elements in the steel. In the aging process, the matrix of the martensite will disperse and precipitate carbides, and the increase of the content of carbides will cause the secondary hardening of the material. When the carbon content exceeds a certain range, the aging effect will decrease. Therefore, the carbon content is in the above range.

[0090] The element Si is generally brought in from scrap steel and pig iron raw materials during smelting. The increase of the silicon content in the steel can improve the strength, and the Si element can also be dissolved in the ε carbide, delay the transformation of the ε carbide into θ carbide, promote the formation of carbides, and improve the stability. However, at the same time, it will lead to a decrease in plasticity and toughness. Therefore, the content of silicon element should not be too high.

[0091] The element Mn has a solid solution strengthening effect, which can improve the hardness and strength of the steel without affecting the ductility of the steel. Mn is also an austenite forming element, and after adding a large amount of Mn, residual austenite structure can be obtained, which can reduce the quenching temperature and hardness of the steel, and reduce the quenching deformation. However, the higher the manganese content, the more serious the overheating sensitivity and the tendency of temper brittleness of the steel. Therefore, the above range is more appropriate.

[0092] V produces fine-grain strengthening and significant precipitation strengthening in steel, produces V4C3 precipitation, and affects the solubility of carbon and nitrogen in ferrite and the diffusion speed of carbon and nitrogen atoms, thereby indirectly affecting the aging strengthening effect.

[0093] Al is a common deoxidizer in steel, which can fix free nitrogen in steel, increase grain coarsening temperature of steel, reduce brittle transition temperature of steel, prevent strain and temperature aging, and improve impact toughness of steel.

[0094] N is similar to carbon in properties and is a basic element causing aging. N combines with Al to form AlN, which can be completely melted into austenite at a high temperature. AlN is precipitated during aging process to achieve strengthening effect.

[0095] P and S are harmful impurity elements in steel. P can greatly increase strength, but easily forms segregation in steel to reduce toughness and welding performance of steel. S easily forms plastic sulfide to seriously anisotropy of steel, which deteriorates impact toughness and processing performance of steel. Therefore, the content of P, S and other impurity elements in steel should be strictly controlled and should not exceed the above range.

[0096] It can be understood by those skilled in the art that the components of the low-carbon alloy steel include but are not limited to the elements listed above, and in addition to the majority of Fe, other unavoidable trace impurities can also be included.

[0097] In some embodiments of the present application, the low-carbon alloy steel has a room temperature yield strength of 480 MPa or more, a tensile strength of 550-675 MPa, an elongation of 18% or more, and a low-temperature impact toughness of 80 J or more at -20°C.

[0098] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application. The experimental methods not specified in the following examples are generally determined according to national standards. If there is no corresponding national standard, the general international standard, conventional conditions, or the conditions suggested by the manufacturer are used.

[0099] Example 1

[0100] The present embodiment provides a preparation method of a low-carbon alloy steel, which comprises the following steps:

[0101] Sa: a converter is used to obtain molten steel, and aluminum is added to the molten steel for deoxidization;

[0102] Sb: the deoxidized molten steel is introduced into an LF furnace, argon is blown for refining, and refined molten steel is obtained;

[0103] Sc: a manganese iron deoxidizer is added to the refined molten steel for deoxidization, and vanadium-nitrogen alloying is performed;

[0104] Sd: the alloyed molten steel is vacuum treated and then cast to prepare a steel billet;

[0105] Se: rough rolling, finish rolling and coiling the billet to obtain a steel coil;

[0106] Sf: after the steel coil is cooled, the steel coil is uncoiled and straightened, and is cut into a preformed steel plate;

[0107] Sg: the preformed steel plate is subjected to solid solution treatment, the temperature and time of the solid solution treatment are shown in Table 3, and after the solid solution treatment, the preformed steel plate is cooled at a cooling rate shown in Table 3 to obtain a post-solid-solution steel plate;

[0108] Sh: the post-solid-solution steel plate is subjected to aging treatment at an aging temperature and for an aging time shown in Table 3, and is then naturally cooled to obtain the low-carbon alloy steel.

[0109] The deoxidation and alloying are performed when the tapping of the LF furnace is 1 / 3, and are completed before the tapping of the LF furnace is 2 / 3.

[0110] The time for tapping of the LF furnace is 3 min.

[0111] The billet is heated to a billet heating temperature shown in Table 2 before rough rolling, and the heating rate is 10 min / cm.

[0112] The rough rolling is performed at a rough rolling temperature shown in Table 2,

[0113] The first-pass reduction rate of the rough rolling is 15%, and the total reduction rate of the last three passes is shown in Table 2.

[0114] The exit thickness of the rough rolling process steel plate is shown in Table 2.

[0115] The total reduction rate of the finish rolling is 70%, and the last-pass total reduction rate is 40%,

[0116] The finish rolling is performed at a finish rolling temperature shown in Table 2.

[0117] The coiling temperature is shown in Table 3.

[0118] The low-carbon alloy steel prepared by the above method is also provided, and the element composition of the low-carbon alloy steel is shown in Table 1, and the thickness of the low-carbon alloy steel is shown in Table 2.

[0119] The process parameters in the embodiment are shown in Tables 2 and 3.

[0120] Embodiment 2

[0121] The differences between the embodiment and Embodiment 1 are shown in Tables 1-3.

[0122] Embodiment 3

[0123] The differences between the embodiment and Embodiment 1 are shown in Tables 1-3.

[0124] Embodiment 4

[0125] The differences between this embodiment and embodiment 1 are shown in Tables 1-3.

[0126] Example 5

[0127] The differences between this embodiment and embodiment 1 are shown in Tables 1-3.

[0128] Example 6

[0129] The differences between this embodiment and embodiment 1 are shown in Tables 1-3.

[0130] Related experiments and effect data:

[0131] First, Tables 1-3 are shown here.

[0132]

[0133] Table 1

[0134]

[0135] Table 2

[0136]

[0137] Table 3

[0138] Mechanical property tests were performed on Examples 1-6, and the results are shown in Table 4.

[0139] (1) Tensile property test: under room temperature conditions, transverse samples were taken from the 1 / 4 thickness of the steel plate, and the yield strength ReL, tensile strength Rm, and elongation A of the steel plate were measured according to GB / T228.1 “Metallic materials-Tensile testing-Part 1: Method of test at room temperature”.

[0140] (2) Low-temperature impact toughness test: under ambient temperature conditions of -20℃, transverse samples were taken from the 1 / 4 thickness of the steel plate, and the test was performed according to GB / T229 “Metallic materials Charpy pendulum impact test method” to obtain the average value of the KV2 impact of the standard sample at -20℃.

[0141] Example Number [R eL (MPa)]]> [R m (MPa)]]> A(％) -20 °C KV2(J) 1 510 635 19 93 102 113 2 535 650 18 80 85 110 3 550 675 22 123 105 110 4 500 625 20 97 121 103 5 530 610 19 90 88 118 6 480 550 20 120 113 104

[0142] As can be seen from Table 3, the low-carbon steel of the present application has very ideal yield strength and tensile strength at room temperature through solid solution treatment and aging treatment, and still has a high impact energy value at -20℃, indicating that it has good strength and toughness matching, and fully meets the use requirements of structural parts.

[0143] A metallographic structure diagram was taken for Example 1, and is shown in Figure 1 .

[0144] From Figure 1It can be found that the metallographic structure of the application is mainly ferrite and pearlite, and after aging treatment, the carbides are uniformly distributed around the ferrite grain boundary, which is more beneficial to the improvement of the strength and toughness of the steel plate.

[0145] Various embodiments of the application can exist in a range of forms; it should be understood that the description in a range form is merely for the convenience and brevity, and should not be understood as a hard limit to the scope of the application; therefore, it should be considered that the described range has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the described range, such as 1, 2, 3, 4, 5 and 6, which applies to any range. In addition, whenever a numerical range is indicated herein, it refers to any cited number (fraction or integer) within the indicated range.

[0146] In this application, the positional words such as "upper" and "lower" are specifically the directions of the drawing surface in the drawings unless otherwise stated. In addition, in the description of the specification, the terms "comprise", "include" and the like mean "including but not limited to". Moreover, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices including a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or devices. Without more limitations, the elements defined by the statement "comprise" do not exclude the presence of other identical elements in the processes, methods, articles or devices including the elements. In this text, the relationship terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. In this text, the "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the following cases: A exists alone, A and B exist together, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of the three associated objects can exist alone, or any at least two of them exist together, for example, for A, and / or B, and / or C, it means that any one of A, B and C exists alone, or any two of them exist together, or all three of them exist together. In this text, "at least one" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of the items, including any combination of single or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b and c can be single or multiple.

[0147] The above description is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications of these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A method of producing a low carbon alloy steel, characterized by, The method comprises the following steps: carrying out converter steelmaking to obtain molten steel, adding aluminum to the molten steel for deoxidization; introducing the deoxidized molten steel into an LF furnace, blowing argon for refining to obtain refined molten steel; adding manganese iron deoxidizer to the refined molten steel for deoxidization and vanadium-nitrogen alloying, the deoxidization and alloying are started when the tapping progress of the LF furnace is 1 / 3, and the tapping progress is completed before 2 / 3; carrying out vacuum treatment on the alloyed molten steel, then carrying out casting, and preparing into a billet; carrying out rough rolling, finish rolling and coiling on the billet to obtain a coil; carrying out uncoiling and straightening on the coil after cooling, and cutting into a preformed plate; carrying out solid solution treatment on the preformed plate at a temperature of 900-930 ℃, cooling the preformed plate after the solid solution treatment at a cooling rate of 50-80 ℃ / s to obtain a solid-solution-treated plate; carrying out aging treatment on the solid-solution-treated plate at 60-80 ℃ for 3-12 h, and then naturally cooling to obtain the low-carbon alloy steel; the low-carbon alloy steel comprises the following components in percentage by mass of the low-carbon alloy steel: C: 0.01-0.03%, Si: 0.01-0.2%, Mn: 0.80%-2.00%, P: 0-0.008%, S: 0-0.003%, N: 0.01-0.03%, Al: 0.015-0.035%, V: 0.15-0.3%, and the balance being Fe and inevitable impurities; the low-carbon alloy steel has a room-temperature yield strength of 480 MPa or more, a tensile strength of 550-675 MPa, an elongation of 18% or more, and a low-temperature impact toughness of 80 J or more at -20 ℃.

2. The method of producing a low carbon alloy steel according to claim 1, characterized by, The temperature of the LF furnace tapping is not less than 1680 ℃; and / or The time of the LF furnace tapping is 2.5-6 min.

3. The method of producing a low carbon alloy steel according to claim 1, characterized by, The billet is heated to 1200-1260 ℃ before rough rolling; and / or The heating rate is 9-15 min / cm.

4. The method of producing a low carbon alloy steel according to claim 1, characterized by, The rough rolling temperature is 1060-1180 ℃; and / or The first-pass reduction rate of the rough rolling is greater than 15%; and / or The outlet thickness of the rough rolling process plate is 3.5-10.5 times the thickness of the low-carbon alloy steel.

5. The method of producing a low carbon alloy steel according to claim 1, wherein The cumulative reduction rate of the finish rolling is not less than 70%; and / or The cumulative reduction rate of the last pass is not less than 40%; and / or The finish rolling temperature is 860-890 ℃.

6. The method of producing a low carbon alloy steel according to claim 1, characterized by, The coiling temperature is 560-600 ℃.

7. A low carbon alloy steel, characterized in that, The low-carbon alloy steel is the low-carbon alloy steel prepared by any one of claims 1-6.

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