CN115502208A - Low-carbon steel prepared by low-temperature rolling process and method thereof - Google Patents

Abstract

The application relates to the field of steel preparation, in particular to low-carbon steel prepared by a low-temperature rolling process and a preparation method thereof; the method comprises the following steps: carrying out first heating, descaling before rough rolling, second heating, descaling before finish rolling and finish rolling on a casting blank to obtain a hot rolled coil; carrying out laminar cooling on the hot rolled coil, and then coiling to obtain low-temperature rolled low-carbon steel; wherein the temperature difference before and after the first heating is less than 250 ℃, and the temperature difference before and after the second heating is less than 100 ℃; the chemical components of the low-carbon steel comprise: c, si, mn, S, P, and the balance of Fe and inevitable impurities; through the first heating and the second heating, the metallographic structure of the casting blank can be changed in an expected manner, the rolling difficulty of rough rolling and finish rolling can be reduced respectively, the temperature difference before and after the first heating is less than 250 ℃ and the temperature difference before and after the second heating is less than 100 ℃ by combining the two heating modes, the energy consumption in the rolling process can be effectively reduced, and the production cost of a rolling production line is reduced.

Description

Low-carbon steel prepared by low-temperature rolling process and method thereof

technical field

The present application relates to the field of steel preparation, in particular to a low-carbon steel prepared by a low-temperature rolling process and a method thereof.

Background technique

The production of low-carbon steel by using a multi-mode continuous casting and rolling production line using a low-temperature rolling process is neither a pure austenite rolling nor a pure ferrite rolling, but multi-mode continuous casting and rolling The production line, like other types of endless rolling production lines, needs heat preservation and heating equipment for heat preservation before finishing rolling.

At present, in the production of low-carbon steel, before rolling, it is generally necessary to use tunnel furnace or induction heating furnace to heat the slab, so that the metallographic structure in the slab begins to change and form the expected metallographic structure. , so as to reduce the difficulty of rolling, but due to the current heating stage of tunnel furnace or induction heating, the temperature needs to be raised by 150 ℃ ~ 300 ℃, resulting in the consumption of a lot of heat in the process of rolling after heating, so as to improve the rolling production The production cost of the rolling line; therefore how to reduce the production cost of the rolling production line is a technical problem that needs to be solved urgently.

Contents of the invention

The application provides a low-carbon steel prepared by a low-temperature rolling process and a method thereof, so as to solve the technical problem of high production cost of a rolling line in the prior art.

In a first aspect, the application provides a method for preparing low-carbon steel by a low-temperature rolling process, the method comprising:

Carrying out first heating, descaling before rough rolling, rough rolling, second heating, descaling before finish rolling and finish rolling on the slab to obtain hot-rolled coils;

Laminar cooling is performed on the hot-rolled coil, and then coiled to obtain low-carbon steel rolled at low temperature;

Wherein, the temperature difference before and after the first heating is <250°C, and the temperature difference before and after the second heating is <100°C.

Optionally, the inlet temperature of the first heating is 900°C-950°C, and the outlet temperature of the first heating is 1050°C-1150°C;

The inlet temperature of the second heating is 900°C-950°C, and the outlet temperature of the second heating is 900°C-1030°C.

Optionally, the first heating time is <20 min, and the second heating time is <10 s.

Optionally, the heating modes of the first heating and the second heating include at least one of tunnel heating and induction heating.

Optionally, the finishing rolling includes finishing rolling with N sets of stands, where N≥3 and N is a positive integer;

Wherein, the reduction rate of the first group of frames>40%, the reduction rate of the second group of frames to the N-1th group of frames<30%, and the reduction rate of the Nth group of frames>25%.

Optionally, the finish rolling end point temperature is 750°C-830°C.

Optionally, the coiling temperature is 650°C-700°C.

Optionally, before performing the first heating, descaling before rough rolling, rough rolling, second heating, descaling before finish rolling and finish rolling to the slab, before obtaining hot-rolled coils, it also includes:

The molten steel is poured to obtain a slab.

Optionally, the pouring includes pouring at a preset casting speed, and the preset casting speed is >5.2m/min.

In a second aspect, the application provides a low-temperature rolling process for preparing low-carbon steel, which is prepared by the method described in the first aspect, and in terms of mass fraction, the chemical composition of the low-carbon steel includes:

C: 0.01%-0.08%, Si: 0.01%-0.1%, Mn: 0.1%-0.3%, S<0.01%, P<0.1%, and the rest are Fe and unavoidable impurities.

Compared with the prior art, the above-mentioned technical solutions provided by the embodiments of the present application have the following advantages:

The embodiment of this application provides a method for preparing low-carbon steel by low-temperature rolling process. By using the first heating before the descaling stage before rough rolling, the metallographic structure of the slab is initially changed, thereby reducing the rolling loss of rough rolling. Improve the rolling efficiency of rough rolling, and then use the second heating before the stage of descaling before finishing rolling, so that the metallographic structure of the slab can be completely changed and reach the expected standard, thereby reducing the difficulty of finishing rolling , improve the rolling efficiency of finish rolling, combined with two heating methods, the temperature required for rolling is increased in stages, and at the same time ensure that the temperature difference before and after the first heating is <250°C, and the temperature difference before and after the second heating is < 100 ℃, can effectively reduce the energy consumption in the rolling process and reduce the production cost of the rolling line.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description serve to explain the principles of the invention.

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, In other words, other drawings can also be obtained from these drawings without paying creative labor.

Fig. 1 is a schematic flow chart of the method provided by the embodiment of the present application;

Fig. 2 is the result schematic diagram of the metallographic structure of the SPHC product of 2mm produced by the multi-mode continuous casting and rolling production line that the embodiment of the application provides;

Fig. 3 is the result schematic diagram of the metallographic structure of the SPHC product of 2mm produced by the semi-continuous rolling production line that the embodiment of the present application provides;

Fig. 4 is the result schematic diagram of the metallographic structure of the SPHC product of 1.5mm produced by the multi-mode continuous casting and rolling production line provided by the embodiment of the application;

Fig. 5 is a schematic diagram of the results of the metallographic structure of the 2mm SPHC product produced by the semi-continuous rolling line provided in the embodiment of the present application.

detailed description

The present invention will be described in detail below in conjunction with specific embodiments and examples, so that the advantages and various effects of the present invention will be presented more clearly. Those skilled in the art should understand that these specific implementations and examples are used to illustrate the present invention, not to limit the present invention.

Throughout the specification, unless otherwise specified, the terms used herein should be understood as 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 invention belongs. In case of conflict, this specification shall take precedence.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

The creative thinking of this application is: the current rolling process for low carbon steel includes ESP production line, CSP production line and semi-continuous rolling production line. Among them, the rolling stage of ESP production line requires the entrance temperature of the finish rolling to be 950°C~ 1050°C, finish rolling exit temperature is 740°C-800°C, cumulative reduction rate of the strip between the first stand and the second stand is 60%-70%, and the rolling reduction rate between the third stand and the fifth stand The cumulative reduction rate is 50% to 65%; while the CSP production line requires the temperature of the slab to be 1000-1050°C, the inlet temperature of the F4 stand to be no more than 870°C, and the final rolling temperature of the F7 stand to be controlled at 780°C to 820°C , and the pass reduction rate of F1, F2, F3 stands is 40% to 65%, and the reduction rate of F4 stand is less than 10%; the semi-continuous rolling production line requires the rough rolling final pass temperature to be 820°C to 860°C ℃ low-temperature austenite temperature zone, finishing rolling entrance temperature is 800℃～850℃, final rolling temperature is 720℃～750℃, coiling temperature is 630℃-660℃, and the r value of DC01 using this process is 1.5～1.8 , the r value of SPCC is 1.2-1.4.

Therefore, the ESP production line, CSP production line and semi-continuous rolling production line are all different from the multi-mode continuous casting and rolling production line. There are related measures to reduce the temperature difference before and after the heating before rolling, so as to reduce energy consumption and save costs.

The technical solutions provided by the embodiments of the present invention are to solve the above-mentioned technical problems, and the general idea is as follows:

In one embodiment of the present application, as shown in Figure 1, a kind of low temperature rolling process is provided to prepare the method for low carbon steel, described method comprises:

S1. Carrying out first heating, descaling before rough rolling, rough rolling, second heating, descaling before finish rolling and finish rolling to the slab to obtain hot rolled coils;

S2. laminar cooling the hot-rolled coil, and then coiling to obtain low-carbon steel rolled at low temperature;

Wherein, the temperature difference before and after the first heating is <250°C, and the temperature difference before and after the second heating is <100°C.

In the embodiment of the present application, the positive effect of the temperature difference before and after the first heating <250°C is that within the range of the temperature difference, it can not only ensure the transformation of the metallographic structure of the slab, but also reduce the rolling difficulty of rough rolling; If the temperature difference is greater than the end point of this range, the temperature will be too high, the burning loss will be aggravated, and the yield will be low.

The positive effect of the temperature difference before and after the second heating <100°C is that within the range of the temperature difference, it can not only ensure the transformation of the metallographic structure of the slab, but also reduce the rolling difficulty of finish rolling; when the value of the temperature difference is greater than The extreme value of this range will cause the temperature to be too high, which will cause the metallographic structure of the steel to change excessively, and affect the effect of rolling, and will also increase the energy consumption of production and increase the production cost of steel.

In an optional embodiment, the inlet temperature of the first heating is 900°C to 950°C, and the outlet temperature of the first heating is 1050°C to 1150°C;

The inlet temperature of the second heating is 900°C-950°C, and the outlet temperature of the second heating is 900°C-1030°C.

In the embodiment of this application, the positive effect of the inlet temperature of the first heating being 900°C to 950°C is to ensure that the slab is in the austenite zone within this temperature range; when the temperature is greater than 950°C, it will lead to increased oxidation burning loss , the temperature is less than 1050 ° C, it will affect the subsequent heating energy consumption.

The positive effect of the outlet temperature of the first heating is 1050°C ~ 1150°C. The positive effect is that within this temperature range, the rolling stability of the rough rolling process is guaranteed; when the temperature is greater than 1150°C, the oxidation burning loss will increase rapidly, and the temperature is less than 1050°C. , It is easy to cause uneven microstructure of the intermediate billet after rough rolling.

The inlet temperature of the second heating is 900°C-950°C, which belongs to the natural temperature drop of the intermediate billet temperature after rough rolling.

The positive effect of the outlet temperature of the second heating is 900 ° C ~ 1030 ° C, the rolling process is guaranteed within this temperature range; when the outlet temperature is < 900 ° C or > 1030 ° C, the final rolling temperature will exceed the design range, Affects the tissue properties of the final product.

In some optional embodiments, the first heating time is <20 min, and the second heating time is <10 s.

In the embodiment of the present application, the positive effect of the first heating time <20 minutes is that within this time range, sufficient first heating can be ensured, the slab reaches the predetermined temperature and the temperature uniformity is good. When the value of time is greater than the end point of this range, it will lead to large oxidation loss and reduced yield.

The positive effect of the second heating time > 10s is that within this time range, sufficient second heating can be ensured, thereby ensuring that the metallographic structure of the slab after rough rolling is completely changed, thereby reducing the rolling difficulty of finish rolling; If the value is less than the end point value of this range, it will lead to insufficient heating, which will affect the change of the metallographic structure of the slab after rough rolling.

In some optional embodiments, the heating modes of the first heating and the second heating include at least one of tunnel heating and induction heating.

In the embodiment of the present application, the heating modes of the first heating and the second heating are limited to ensure that the heating is sufficient to promote the complete change of the metallographic structure of the slab after two heatings, and to ensure that the temperature difference before and after the first heating is <250°C , the temperature difference before and after the second heating is less than 100°C, thereby reducing heating energy consumption and production cost.

In some optional embodiments, the finish rolling includes finishing rolling with N groups of stands, where N≥3 and N is a positive integer;

Wherein, the reduction rate of the first group of frames>40%, the reduction rate of the second group of frames to the N-1th group of frames<30%, and the reduction rate of the Nth group of frames>25%.

In the embodiment of the present application, the positive effect of the reduction rate of the first group of racks > 40% is to promote austenite recrystallization, which is beneficial to refine the grains of the final product and ensure strong plasticity; when the reduction rate is less than The end value of this range will reduce the strong plasticity of the product.

The positive effect of the reduction rate <30% from the second group of racks to the N-1th group of racks is to ensure uniform size after deformation when pro-eutectoid ferrite appears; when the reduction rate is greater than the range Endpoint values will result in inhomogeneous austenite and ferrite sizes after deformation.

The positive effect of the reduction rate > 25% of the Nth group of racks is to meet the size requirements of the final product while ensuring the uniformity of the structure in the thickness direction of the product; when the reduction rate is less than the end point value of this range, it will cause The adverse effect is that the tissue in the thickness direction is easy to be uneven, and the phenomenon of tissue delamination occurs.

In some optional embodiments, the finish rolling end temperature is 750°C-830°C.

In the embodiment of the present application, the positive effect of the finish rolling end temperature being 750°C to 830°C is to reduce the yield ratio and improve the product forming ability on the basis of stable rolling; when the temperature is greater than 830°C , close to conventional austenitic rolling, and the yield ratio increases. When the temperature is lower than 750°C, the deformation resistance of the intermediate billet in the rear stand will increase sharply, which will affect the rolling stability.

In some optional embodiments, the coiling temperature is 650°C-700°C.

In the examples of this application, the positive effect of the coiling temperature being 650°C to 700°C is to ensure the recovery and growth of grains; when the temperature is greater than 700°C, the grain size is large and the strength is very low. When the temperature is less than 650℃, the recovery of deformed ferrite will be insufficient, and the anisotropy of mechanical properties will be large.

In some optional embodiments, the first heating, descaling before rough rolling, rough rolling, second heating, descaling before finish rolling and finish rolling are carried out on the slab, before obtaining hot rolled coils, including:

S101. Pouring molten steel to obtain a cast slab.

In some optional embodiments, the pouring includes pouring at a preset casting speed, and the preset casting speed >

5.2m/min.

In the embodiment of this application, the positive effect of the preset casting speed>5.2m/min is to ensure that the temperature drop in the finishing rolling area is reasonable; The temperature drop in the rolling area is large, and the same finish rolling entrance temperature, the final rolling temperature is low, which affects the product performance.

In one embodiment of the present application, a kind of low-carbon steel prepared by low-temperature rolling process is provided, and the low-carbon steel is prepared by the method, and in mass fraction, the chemical composition of the low-carbon steel includes:

C: 0.01%-0.08%, Si: 0.01%-0.1%, Mn: 0.1%-0.3%, S<0.01%, P<0.1%, and the rest are Fe and unavoidable impurities.

In the embodiment of the present application, the positive effect of the mass fraction of C being 0.01% to 0.08% is to ensure that the phase transition temperature in the rolling process is within the predicted range; when the value of the mass fraction is greater than or less than the endpoint value of the range, the The production stability and final mechanical properties of the product are unqualified.

Example 1

Take the DC01 product with a thickness of 2mm produced by the multi-mode continuous casting and rolling production line as an example:

As shown in Figure 1, a method for preparing low-carbon steel by a low-temperature rolling process, comprising:

S101. Pouring molten steel to obtain a slab;

S1. Carrying out first heating, descaling before rough rolling, rough rolling, second heating, descaling before finish rolling and finish rolling to the slab to obtain hot rolled coils;

S2. Laminar cooling is performed on the hot-rolled coil, and then coiled to obtain low-carbon steel rolled at low temperature.

The inlet temperature of the first heating is 926°C, and the outlet temperature of the first heating is 1123°C;

The inlet temperature of the second heating is 917°C, and the outlet temperature of the second heating is 1020°C.

The time for the first heating is 16 minutes, and the time for the second heating is 8 s.

The heating mode of the first heating is tunnel heating, and the heating mode of the second heating is induction heating.

Finish rolling includes finishing rolling with 5 groups of stands; among them, the reduction rate of the first group of stands is 45%, the reduction rate of the second group to the fourth group of stands is <30%, and the fifth group of stands The reduction rate of the frame was 26%.

The finish rolling end point temperature was 772°C.

The coiling temperature was 676°C.

Pouring includes pouring at a preset casting speed, which is 5.3m/min.

A low-carbon steel prepared by a low-temperature rolling process, the low-carbon steel is prepared by the method, and in mass fraction, the chemical composition of the low-carbon steel includes:

C: 0.02%, Si: 0.01%, Mn: 0.1%, S<0.01%, P<0.1%, and the rest are Fe and unavoidable impurities.

Example 2

Embodiment 2 is compared with embodiment 1, and the difference between embodiment 2 and embodiment 1 is:

Take the SPHC with a thickness of 1.5mm produced by the multi-mode continuous casting and rolling production line as an example:

The inlet temperature of the first heating is 931°C, and the outlet temperature of the first heating is 1128°C;

The inlet temperature of the second heating is 918°C, and the outlet temperature of the second heating is 1030°C.

The first heating time is 15 minutes, and the second heating time is 7s.

Wherein, the reduction rate of the first group of frames is 42%, the reduction rate of the second group to the fourth group of frames <30%, and the reduction rate of the fifth group of frames is 28%.

The finish rolling end point temperature was 768°C.

The coiling temperature was 669°C.

The preset pulling speed is 5.3m/min

In terms of mass fraction, the chemical composition of low carbon steel includes:

C: 0.04%, Si: 0.03%, Mn: 0.15%, S<0.01%, P<0.1%, and the rest are Fe and unavoidable impurities.

Comparative example 1

Take DC01 with a thickness of 2.0mm produced by the conventional production process of the multi-mode continuous casting and rolling production line as an example:

The inlet temperature of the first heating is 935°C, and the outlet temperature of the first heating is 1168°C;

The inlet temperature of the second heating is 938°C, and the outlet temperature of the second heating is 1182°C.

The finish rolling end point temperature was 872°C.

The coiling temperature was 619°C.

In terms of mass fraction, the chemical composition of low carbon steel includes:

C: 0.02%, Si: 0.01%, Mn: 0.1%, S<0.01%, P<0.1%, and the rest are Fe and unavoidable impurities.

Comparative example 2

Take the SPHC with a thickness of 1.5mm produced by the conventional production process of the multi-mode continuous casting and rolling production line as an example:

The inlet temperature of the first heating is 936°C, and the outlet temperature of the first heating is 1157°C;

The inlet temperature of the second heating is 928°C, and the outlet temperature of the second heating is 1153°C.

The finish rolling end point temperature was 861°C.

The coiling temperature was 617°C.

In terms of mass fraction, the chemical composition of low carbon steel includes:

C: 0.04%, Si: 0.03%, Mn: 0.15%, S<0.01%, P<0.1%, and the rest are Fe and unavoidable impurities.

Comparative example 3

Take the semi-continuous rolling line to produce 2mm DC01 products as an example:

The tapping temperature of the heating furnace is 1200°C;

The exit temperature of finish rolling is 880℃;

The coiling temperature is 640°C.

Chemical composition includes:

C: 0.02%, Si: 0.01%, Mn: 0.1%, S<0.01%, P<0.1%, and the rest are Fe and unavoidable impurities.

Comparative example 4

Take the production of 1.5mm SPHC products in the semi-continuous rolling line as an example:

The tapping temperature of the heating furnace is 1180°C;

The exit temperature of finish rolling is 870℃;

The coiling temperature is 620°C.

Chemical composition includes:

C: 0.04%, Si: 0.03%, Mn: 0.15%, S<0.01%, P<0.1%, and the rest are Fe and unavoidable impurities.

Related experiments:

The cost of the induction heating stage in each embodiment and comparative example process is counted respectively, and the mechanical properties of the product obtained are counted simultaneously, and the results are shown in Table 1.

Test methods for related experiments:

Mechanical properties of the product: adopt GB/T228-09 metal room temperature tensile test method to measure the yield strength, tensile strength and elongation of the product; adopt GB/T5027-2016 to measure the work hardening index n value and plastic strain The ratio r value is measured.

Table 1

Specific analysis of Table 1:

The yield strength (R _p0.2 ) refers to the elongation strength of the steel when the non-proportional elongation is 0.2%. The more the yield strength meets the standard, the better the mechanical properties of the steel are.

Tensile strength (R _m ) refers to the maximum stress per unit area before the specimen is broken. The more the tensile strength meets the standard, the better the mechanical properties of the steel.

The elongation after fracture refers to the percentage of the ratio of the total deformation ΔL of the gauge section after tensile fracture of the sample to the original gauge length L. The more the total elongation meets the standard, the better the mechanical properties of the steel.

By the data of embodiment 1-3 as can be known:

Using the method of this application, through the first heating and the second heating, not only can the metallographic structure of the slab complete the expected change, but also reduce the rolling difficulty of rough rolling and finish rolling respectively, and combine the two heating methods , the temperature required for rolling is raised in stages to ensure that the temperature difference before and after the first heating is less than 250°C, and the temperature difference before and after the second heating is less than 100°C, which can effectively reduce the energy consumption during the rolling process and reduce the Production costs of the rolling line.

From the data of Comparative Example 1-2, it can be seen that:

If the multi-mode continuous casting and rolling production line of the application is not adopted, and the semi-continuous rolling production line is used to produce steel products, due to the large temperature difference between the heating and heating of the semi-continuous rolling production line, the steel products produced by the semi-continuous rolling production line The performance of the steel produced by the continuous casting and rolling production line is relatively low.

One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:

(1) The method provided in the embodiment of this application, through the first heating and the second heating, can not only make the metallographic structure of the slab complete the expected change, but also reduce the rolling difficulty of rough rolling and finish rolling respectively, and combine The two-time heating method increases the temperature required for rolling in stages to ensure that the temperature difference before and after the first heating is less than 250°C, and the temperature difference before and after the second heating is less than 100°C, which can effectively reduce the rolling process. energy consumption and reduce the production cost of the rolling line.

(2) According to the method provided in the embodiments of the present application, the steel product obtained has the advantages of coarse grains in the structural properties and low yield strength in the mechanical properties, so it has good forming ability.

(4) The low-carbon steel provided in the embodiment of the present application has a uniform microstructure and stable product performance.

Explanation of the drawings:

Fig. 2 is the result schematic diagram of the metallographic structure of the DC01 product that the multi-mode continuous casting and rolling production line that Fig. 2 provides for the embodiment of the application produces 2mm;

Fig. 3 is the result schematic diagram of the metallographic structure of the DC01 product of 2mm produced by the semi-continuous rolling production line that the embodiment of the application provides;

From the data in Figure 2 and Figure 3, it can be seen that the 2mm SPHC produced by the multi-mode continuous casting and rolling line has relatively coarse grains, low yield strength, and better forming ability.

Fig. 4 is the result schematic diagram of the metallographic structure of the SPHC product of 1.5mm produced by the multi-mode continuous casting and rolling production line provided by the embodiment of the application;

Fig. 5 is a schematic diagram of the results of the metallographic structure of the 2mm SPHC product produced by the semi-continuous rolling line provided in the embodiment of the present application.

It can be seen from Figure 4 and Figure 5 that the 1.5mm SPHC produced by the multi-mode continuous casting and rolling production line has relatively coarse grains, low yield strength, and better formability.

It should be noted that in this article, relative 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 these No such actual relationship or order exists between entities or operations. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the statement "comprising..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

Neither the endpoints of the ranges nor any values disclosed herein are limited to that precise range or value, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

The above descriptions are only specific embodiments of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Accordingly, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims (10)

1. a method for preparing low-carbon steel by low-temperature rolling technique, is characterized in that, described method comprises: Carrying out first heating, descaling before rough rolling, rough rolling, second heating, descaling before finish rolling and finish rolling on the slab to obtain hot-rolled coils; Laminar cooling is performed on the hot-rolled coil, and then coiled to obtain low-carbon steel rolled at low temperature; Wherein, the temperature difference before and after the first heating is <250°C, and the temperature difference before and after the second heating is <100°C. 2. The method according to claim 1, characterized in that the inlet temperature of the first heating is 900°C-950°C, and the outlet temperature of the first heating is 1050°C-1150°C; The inlet temperature of the second heating is 900°C-950°C, and the outlet temperature of the second heating is 900°C-1030°C. 3. The method according to claim 1, characterized in that, the time of the first heating is <20 min, and the time of the second heating is <10 s. 4. The method according to any one of claims 1-3, wherein the heating modes of the first heating and the second heating comprise at least one of tunnel heating and induction heating. 5. The method according to claim 1, characterized in that, the finishing rolling comprises finishing rolling with N groups of stands, where N≥3 and N is a positive integer; Wherein, the reduction rate of the first group of frames is >40%, the reduction rate of the second group to the N-1th group of frames is <30%, and the reduction rate of the Nth group of frames is >25%. 6. The method according to claim 1, characterized in that, the finish rolling end point temperature is 750°C-830°C. 7. The method according to claim 1, characterized in that, the coiling temperature is 650°C-700°C. 8. The method according to claim 1, characterized in that, the first heating, descaling before rough rolling, rough rolling, second heating, descaling before finish rolling and finish rolling are carried out to the slab to obtain hot rolled Before volume, also include: The molten steel is poured to obtain a slab. 9 . The method according to claim 8 , wherein the pouring comprises pouring at a preset casting speed, and the preset casting speed is >5.2 m/min. 10. A low-carbon steel prepared by a low-temperature rolling process, characterized in that, the low-carbon steel is prepared by the method according to any one of claims 1-9, and in mass fraction, the low-carbon steel has Chemical composition includes: C: 0.01% to 0.08%, Si: 0.01% to 0.1%, Mn: 0.1% to 0.3%, S<0.01%, P<0.1%, and the rest are Fe and unavoidable impurities.

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