Large-piece-weight wind power steel and preparation method thereof

Abstract

The invention relates to large-piece-weight wind power steel and a preparation method thereof.The method comprises the steps that at least two first steel billets with set chemical components are subjected to first heating and first rolling, and corresponding second steel billets are obtained; compounding all the corresponding second steel billets to obtain a composite steel billet; the composite steel billet is subjected to second heating and second rolling, and a hot rolled plate is obtained; and the hot-rolled plate is subjected to first cooling, normalizing and second cooling, and the large-piece-weight wind power steel is obtained. The prepared large-piece-weight wind power steel meets the following performance that the yield strength of positions with different thicknesses is larger than or equal to 390 MPa, and the yield strength difference of the positions with different thicknesses is smaller than or equal to 50 MPa; the tensile strength is greater than or equal to 530MPa, and the tensile strength difference at different thickness positions is less than or equal to The impact value is greater than or equal to 120J; and the thickness-direction section shrinkage rate is not less than 45%.

Description

Technical Field

[0001] The present application relates to the technical field of medium and thick plate production and manufacturing, and in particular to a large unit weight steel for wind power and a preparation method thereof. Background Art

[0002] As a renewable energy source, wind power generation has the advantages of short construction period, flexible installed capacity, low operation and maintenance costs, and has broad development prospects. In recent years, with the rapid advancement of the national carbon peak and carbon neutrality strategies, the wind power industry has achieved rapid development. From the development trend of the wind power industry, the capacity of single units continues to increase. The thickness and width of steel plates for wind power are required to increase continuously, and the steel plates are required to have high strength, low yield ratio, excellent low-temperature toughness and mechanical properties in the thickness direction; and higher requirements are put forward for the uniformity of mechanical properties in the thickness direction, requiring normalizing for delivery.

[0003] In order to meet the high unit weight and performance requirements of wind power steel, the traditional process uses die casting, which has low yield rate, high cost and poor uniformity of mechanical properties in the thickness direction. Restricted by billet size and rolling mill capacity, the unit weight of wind power steel produced by continuous casting billets is difficult to meet the requirements, and the low temperature toughness and mechanical properties in the thickness direction are poor. Summary of the invention

[0004] The present application provides a heavy unit weight steel for wind power generation and a preparation method thereof, in order to solve the following technical problem: how to improve the uniformity of mechanical properties of heavy unit weight steel for wind power generation in the thickness direction.

[0005] In a first aspect, the present application provides a method for preparing a large unit weight steel for wind power generation, the method comprising:

[0006] Performing a first heating and a first rolling on at least two first steel billets having set chemical compositions to obtain corresponding second steel billets;

[0007] Compounding all the corresponding second steel billets to obtain a composite steel billet;

[0008] The composite steel billet is subjected to second heating and second rolling to obtain a hot-rolled plate;

[0009] The hot-rolled plate is subjected to a first cooling, a normalizing and a second cooling to obtain a high unit weight steel for wind power generation.

[0010] Optionally, the first heating temperature is 1210°C to 1250°C.

[0011] Optionally, the process parameters of the first rolling include: a single-pass reduction rate of the last two passes ≥ 10%, and a rolling speed of 1.0 m / s to 1.2 m / s.

[0012] Optionally, the second heating temperature is 1120°C to 1160°C.

[0013] Optionally, the process parameters of the second rolling include: a single-pass reduction rate of the last two passes ≥ 20%, a rolling speed of 1.0 m / s to 1.2 m / s, and a final rolling temperature ≥ 980°C.

[0014] Optionally, the process parameters of the first cooling include: a cooling rate of 10°C / s to 20°C / s, and a final cooling temperature of 600°C to 660°C.

[0015] Optionally, the normalizing temperature is 875°C to 885°C.

[0016] Optionally, the process parameters of the second cooling include: a cooling rate of 5°C / s to 12°C / s, and a final cooling temperature of 530°C to 600°C.

[0017] Optionally, the set chemical composition includes: C, Si, Mn, Alt, Nb, Ti, V, Cu, P, S and Fe; wherein, in terms of mass fraction,

[0018] The C content is 0.16% to 0.18%, the Si content is 0.40% to 0.50%, the Mn content is 1.50% to 1.60%, the Alt content is 0.02% to 0.05%, the Nb content is 0.015% to 0.025%, the Ti content is 0.01% to 0.02%, the V content is 0.03% to 0.06%, the Cu content is 0.2% to 0.3%, the P content is 0.01% to 0.02%, and the S content is <0.003%.

[0019] In the second aspect, the present application provides a high-weight steel for wind power generation prepared by the method described in any embodiment of the first aspect, wherein the high-weight steel for wind power generation meets the following properties: yield strength at different thickness positions ≥390MPa, and the yield strength difference at different thickness positions ≤50MPa; tensile strength ≥530MPa, and the tensile strength difference at different thickness positions ≤30MPa; impact value ≥120J; and cross-sectional shrinkage rate in the thickness direction ≥45%.

[0020] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0021] The preparation method of the heavy wind power steel provided in the embodiment of the present application includes: performing a first heating and a first rolling on at least two first steel billets with set chemical composition to obtain corresponding second steel billets; compounding all the corresponding second steel billets to obtain a compound steel billet; performing a second heating and a second rolling on the compound steel billet to obtain a hot-rolled plate; performing a first cooling, normalizing and a second cooling on the hot-rolled plate to obtain a heavy wind power steel. Performing a first heating on the first steel billet with set chemical composition can fully soften the first steel billet, thereby reducing the deformation resistance of the subsequent rolling mill and increasing the rolling single-pass reduction rate, and at the same time fully dissolving the alloy elements in the first steel billet, thereby improving the internal quality and performance of the steel plate; performing a first rolling on the first steel billet after the first heating can cause the first steel billet to recrystallize throughout its thickness, refine the first steel billet structure and improve its internal quality; compounding at least two second steel billets can increase the billet thickness, thereby increasing the rolling compression ratio and billet weight, thereby improving the target heavy wind power steel. Internal quality and unit weight; the second heating of the composite steel billet can further refine the structure in the composite steel billet, and the second rolling of the composite steel billet after the second heating can make the full thickness of the composite steel billet recrystallize, refine the structure of the composite steel billet and improve its internal quality; the first cooling of the hot-rolled plate can make the hot-rolled plate have refined ferrite and pearlite structure; normalizing can make the hot-rolled plate after the first cooling achieve further grain refinement and uniform structure through austenitization; the second cooling can refine the structure of the hot-rolled plate after normalizing and increase the pearlite content, improve its impact toughness and strength. In summary, the uniformity of mechanical properties in the thickness direction of high unit weight wind power steel is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 A schematic flow chart of a method for preparing a large unit weight steel for wind power generation provided in an embodiment of the present application;

[0025] Figure 2 A microstructure diagram of a large unit weight steel for wind power provided in Example 1 of the present application;

[0026] Figure 3 A microstructure diagram of a large unit weight steel for wind power provided in Example 2 of the present application;

[0027] Figure 4 This is a microstructure diagram of a large single weight steel for wind power provided in Example 3 of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have 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 range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0030] In this application, the terms "include", "comprising", etc. mean "including but not limited to". In this document, relational terms such as "first" and "second" are used only 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 these entities or operations.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0032] In a first aspect, the present application provides a method for preparing large unit weight steel for wind power generation. Figure 1 A schematic diagram of a process for preparing a large unit weight steel for wind power provided in an embodiment of the present application; see Figure 1 , the method comprising:

[0033] S1, performing a first heating and a first rolling on at least two first steel billets having set chemical compositions to obtain corresponding second steel billets;

[0034] In some embodiments, the set chemical composition includes: C, Si, Mn, Alt, Nb, Ti, V, Cu, P, S and Fe; wherein, in terms of mass fraction,

[0035] The C content is 0.16% to 0.18%, the Si content is 0.40% to 0.50%, the Mn content is 1.50% to 1.60%, the Alt content is 0.02% to 0.05%, the Nb content is 0.015% to 0.025%, the Ti content is 0.01% to 0.02%, the V content is 0.03% to 0.06%, the Cu content is 0.2% to 0.3%, the P content is 0.01% to 0.02%, and the S content is <0.003%.

[0036] In the embodiment of the present application, Nb, V, and Ti are micro-alloyed, and Cu and V precipitation strengthening are exerted at the same time. A high C (0.16-0.18) composition design is adopted to improve the strength by increasing the pearlite content. The C element is the cheapest and best strengthening element. By increasing the C content, alloy addition is reduced; more Si and Mn elements are added to improve the strength through solid solution strengthening and reduce the strength reduction after normalizing; less Nb elements are added to exert the fine grain strengthening effect of Nb and reduce the effect of Nb inhibiting recrystallization; Cu and V elements are added to improve the strength through fine grain strengthening and precipitation strengthening; P is a harmful element and has a very adverse effect on toughness and plasticity. Its content should be reduced, but at the same time P is a very good strengthening element, so the upper and lower limits of the P element are controlled, and the Alt and S contents in the steel are limited. For example, the C content may be 0.16%, 0.17%, 0.18%, etc., the Si content may be 0.40%, 0.45%, 0.50%, etc., the Mn content may be 1.50%, 1.55%, 1.60%, etc., the Alt content may be 0.02%, 0.03%, 0.04%, 0.05%, etc., the Nb content may be 0.015%, 0.017%, 0.019%, 0.021%, etc. %, 0.023%, 0.025%, etc., the content of Ti can be 0.01%, 0.015%, 0.02%, etc., the content of V can be 0.03%, 0.04%, 0.05%, 0.06%, etc., the content of Cu can be 0.2%, 0.25%, 0.3%, etc., the content of P can be 0.01%, 0.015%, 0.02%, etc., the content of S can be 0.002%, 0.0015%, etc. In addition, the carbon equivalent CEV of the above-mentioned steel for wind power is 0.450~0.480; its calculation formula is as follows: CEV=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15, where it is calculated by the mass fraction of chemical elements.

[0037] In some embodiments, the first heating temperature is 1210°C to 1250°C.

[0038] In the embodiment of the present application, the first steel billet is cold loaded into the furnace and heated at a high temperature using the first heating temperature, so that the first steel billet can be fully softened, the deformation resistance of the subsequent rolling mill can be reduced, and the rolling single pass reduction rate can be increased, so as to improve the internal quality of the first steel billet. At the same time, the high temperature heating makes the alloy elements fully dissolved, which is helpful to improve the internal quality and performance of the first steel billet. If the temperature of the first heating is too low, to a certain extent, the deformation resistance of the subsequent rolling mill is large, and the single pass reduction rate of recrystallization rolling is small, thereby causing the internal quality and performance of the first steel billet to deteriorate. At the same time, if the temperature of the first heating is too low, to a certain extent, it makes it difficult for the Nb element to be fully dissolved, and the subsequent rolling process cannot fully exert the solid solution strengthening and precipitation strengthening effects, which will cause the uniformity of the mechanical properties in the thickness direction of the first steel billet to deteriorate; if the temperature of the first heating is too high, to a certain extent, the structure of the first steel billet will grow abnormally, and finally the uniformity of the mechanical properties in the thickness direction of the first steel billet will deteriorate. Exemplarily, the temperature of the first heating may be 1210° C., 1220° C., 1230° C., 1240° C., 1250° C., etc.; the time of the first heating may be 400 min to 600 min.

[0039] In some embodiments, the process parameters of the first rolling include: the single pass reduction rate of the last two passes ≥

[0040] 10%, rolling speed 1.0m / s~1.2m / s.

[0041] In the embodiment of the present application, the first steel billet is directly rolled into the required steel plate size after being taken out of the furnace, and the process parameters of the first rolling are used, that is, a high temperature, low speed and large reduction complete recrystallization rolling process is adopted to make the first steel billet recrystallize throughout its thickness, refine the structure of the first steel billet and improve the internal quality; and the rolling process is not temperature controlled, so as to avoid the growth of the structure of the first steel billet during the waiting process, and at the same time improve the rolling efficiency. Exemplarily, in the process parameters of the first rolling, the reduction rate of the last two passes can be 10%, 11%, 12%, 13%, etc., and the rolling speed can be 1.0m / s, 1.1m / s, 1.2m / s, etc.

[0042] In addition, the S1 step includes: (1) smelting: using converter smelting, through top and bottom composite blowing; using LF furnace and VD furnace vacuum treatment to reduce the content of harmful gases such as O, N, H, etc.; (2) continuous casting: designing the continuous casting billet (first billet) billet shape, with a thickness of 400mm and a width of 1650-2400 (mm), controlling the inclusions of Class A, Class B, and Class Ds to not exceed 2.0, the inclusions of Class C to not exceed 1.0, and the inclusions of Class D to not exceed 1.5.

[0043] S2, compounding all the corresponding second steel billets to obtain a composite steel billet;

[0044] In the embodiment of the present application, at least two second steel billets are compounded to increase the thickness of the steel billet, thereby improving the rolling compression ratio and the weight of the steel billet, thereby improving the internal quality and unit weight of the target large unit weight wind power steel. Exemplarily, S2 specifically includes: after the second steel billet is stacked and cooled to room temperature, one surface of each of the two second steel billets is ground to be smooth and free of oxidized iron scale, the ground surfaces of the two second steel billets are compounded, the four sides after stacking are welded and vacuumed to ensure that the bonding surface is in a vacuum state, and the preparation of the composite steel billet is completed.

[0045] S3, performing a second heating and a second rolling on the composite steel billet to obtain a hot-rolled plate;

[0046] In some embodiments, the second heating temperature is 1120°C to 1160°C.

[0047] In an embodiment of the present application, the composite steel billet is heated in a furnace, and the second heating temperature is used for low-temperature heating. The above-mentioned first heating has fully dissolved the alloy elements, and the second heating adopts low-temperature heating for the purpose of obtaining a finer structure and improving the mechanical properties of the composite steel billet. If the temperature of the second heating is too low, to a certain extent, it will cause the entire rolling process to be difficult to be carried out in the recrystallization zone, resulting in mixed crystals and affecting impact toughness. If the temperature of the second heating is too high, to a certain extent, it will cause abnormal growth of the structure, and the uniformity of the mechanical properties of the composite steel billet in the thickness direction will deteriorate. Exemplarily, the temperature of the above-mentioned second heating can be 1120°C, 1130°C, 1140°C, 1150°C, 1160°C, etc.; the time of the second heating can be 500min~700min.

[0048] In some embodiments, the process parameters of the second rolling include: a single-pass reduction ratio of the last two passes is ≥ 20%, a rolling speed is 1.0 m / s to 1.2 m / s, and a final rolling temperature is ≥ 980°C.

[0049] In the embodiment of the present application, the composite steel billet is directly rolled into the required steel plate size after being taken out of the furnace, and the process parameters of the second rolling mentioned above are used, that is, a low-speed, large-reduction complete recrystallization rolling process is adopted to make the composite steel billet recrystallize throughout the thickness, refine the structure and improve the internal quality. And the rolling process is not temperature-controlled, which avoids the growth of the structure of the composite steel billet during the waiting process and improves the rolling efficiency. Exemplarily, in the process parameters of the second rolling mentioned above: the single-pass reduction rate of the last two passes can be 20%, 21%, 22%, 23%, etc., the rolling speed can be 1.0m / s, 1.1m / s, 1.2m / s, etc., and the final rolling temperature can be 980℃, 990℃, 1000℃, 1010℃, etc.

[0050] S4. Performing a first cooling, normalizing and a second cooling on the hot-rolled plate to obtain a high unit weight steel for wind power generation.

[0051] In some embodiments, the process parameters of the first cooling include: a cooling rate of 10°C / s to 20°C / s, and a final cooling temperature of 600°C to 660°C.

[0052] In the embodiment of the present application, the first cooling is realized by cooling with the accelerated cooling control system (ACC) after rolling. The process parameters of the first cooling can make the hot-rolled plate have refined ferrite and pearlite structures; if the final cooling temperature is too low, bainite or martensite structures will appear in the hot-rolled plate to a certain extent, resulting in the deterioration of the mechanical properties of the hot-rolled plate after subsequent normalizing; if the final cooling temperature is too high, the structure of the hot-rolled plate will be too coarse to a certain extent, resulting in the deterioration of the uniformity of the mechanical properties in the thickness direction of the hot-rolled plate after subsequent normalizing. Exemplarily, in the process parameters of the first cooling, the cooling rate can be 10℃ / s, 12℃ / s, 14℃ / s, 16℃ / s, 18℃ / s, 20℃ / s, etc.; the final cooling temperature can be 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, 660℃, etc.

[0053] In some embodiments, the normalizing temperature is 875°C to 885°C.

[0054] In the embodiment of the present application, normalizing can refine the grains and homogenize the structure of the hot-rolled plate after the first cooling by austenitizing. For example, the temperature of the normalizing can be 875°C, 880°C, 885°C, etc. The normalizing time at the furnace temperature can be 1.9 to 2.0 times the final steel plate thickness (min).

[0055] In some embodiments, the process parameters of the second cooling include: a cooling rate of 5°C / s to 12°C / s, and a final cooling temperature of 530°C to 600°C.

[0056] In the embodiment of the present application, the hot-rolled plate after normalizing is subjected to a second cooling after being taken out of the furnace, and the second cooling adopts a water cooling method. The process parameters of the second cooling can further refine the ferrite and pearlite structures in the hot-rolled plate after normalizing. The small cooling rate and low final cooling can refine the structure of the hot-rolled plate after normalizing and increase its pearlite content, thereby improving the impact toughness and strength of the hot-rolled plate after normalizing. If the final cooling temperature is too low, bainite or martensite structure will be generated on the surface of the hot-rolled plate after normalizing to a certain extent, and the impact toughness will deteriorate; if the final cooling temperature is too high, the structure will be too coarse and the mechanical properties will deteriorate. Exemplarily, in the process parameters of the second cooling mentioned above: the cooling rate can be 5℃ / s, 7℃ / s, 9℃ / s, 11℃ / s, 12℃ / s, etc., and the final cooling temperature can be 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, etc.

[0057] In the second aspect, the present application provides a high-weight steel for wind power generation prepared by the method described in any embodiment of the first aspect, wherein the high-weight steel for wind power generation meets the following properties: yield strength at different thickness positions ≥390MPa, and the yield strength difference at different thickness positions ≤50MPa; tensile strength ≥530MPa, and the tensile strength difference at different thickness positions ≤30MPa; impact value ≥120J; and cross-sectional shrinkage rate in the thickness direction ≥45%.

[0058] At present, the traditional process adopts die casting, and the thickness of the die casting billet is large. The rolling force during the rolling process is difficult to penetrate into the core of the steel plate, resulting in poor mechanical properties in the thickness direction and uniformity of mechanical properties in the thickness direction. In the embodiment of the present application, by compounding and rolling after rolling, the steel plate is made high in strength and good in low temperature toughness. At the same time, the mechanical properties in the thickness direction are excellent and the mechanical properties in the thickness direction are uniform. The large single-weight and large single-weight steel plates for wind power generation can simultaneously meet the requirements of high strength, low yield strength ratio, good low temperature toughness and mechanical properties in the thickness direction. The mechanical properties in the thickness direction of the embodiment of the present application are specifically reflected as follows: the yield strength at different positions of the thickness is ≥390MPa, and the yield strength difference at different positions is ≤50MPa; the tensile strength difference at different positions is ≤30MPa; the section shrinkage rate in the thickness direction is ≥45%.

[0059] The heavy unit weight steel for wind power generation is realized based on the preparation method of the heavy unit weight steel for wind power generation mentioned above. The specific steps of the preparation method of the heavy unit weight steel for wind power generation can refer to the above embodiment. Since the heavy unit weight steel for wind power generation adopts part or all of the technical solutions of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be described one by one here.

[0060] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0061] The embodiment of the present application provides a method for preparing heavy unit weight steel for wind power. Please refer to the chemical composition (wt%) of the heavy unit weight steel for wind power shown in Table 1, the preparation process parameters of the heavy unit weight steel for wind power shown in Table 2, and the mechanical properties of the heavy unit weight steel for wind power shown in Table 3.

[0062] Table 1 Chemical composition (wt%) of heavy steel for wind power, the rest is Fe and unavoidable impurities

[0063]

[0064] Table 2 Process parameters of a heavy, high-performance, heavy steel plate for wind power

[0065]

[0066]

[0067] Table 2 Process parameters of a heavy, high-performance, heavy steel plate for wind power (continued)

[0068]

[0069] Table 3 Mechanical properties of heavy steel for wind power

[0070]

[0071]

[0072] In Examples 1 to 3, the high-weight steel plates for wind power generation are realized to simultaneously meet the requirements of high strength, low yield strength ratio, good low-temperature toughness, and good uniformity of mechanical properties in the thickness direction. The yield strength at different positions of the thickness is ≥390MPa, and the difference in yield strength at different positions is ≤50MPa; the tensile strength is ≥530MPa, and the difference in tensile strength at different positions is ≤30MPa, and the impact value is ≥120J; the section shrinkage in the thickness direction is ≥45%. Figure 2 A microstructure diagram of a large unit weight steel for wind power provided in Example 1 of the present application; Figure 3 A microstructure diagram of a large unit weight steel for wind power provided in Example 2 of the present application; Figure 4 A microstructure diagram of a large unit weight wind power steel provided in Example 3 of the present application; see Figure 2 to Figure 4, indicating that the microstructure of the large unit weight wind power steel provided by the embodiment of the present application is fine and uniform. In comparative example 1, the Nb element is too much, and the final cooling temperature of the first cooling after rolling is too low, the impact value of thickness 1 / 4 and thickness 1 / 2, and the cross-sectional shrinkage rate in the thickness direction are deteriorated; in comparative example 2, the amount of C element added is too little, and the yield strength and tensile strength are significantly reduced; in comparative example 3, the composite billet process is not used for rolling, and the amount of C element added is too much, the unit weight of the steel plate is small, and the strength is improved, but the yield strength at different positions exceeds 60MPa, the tensile strength difference exceeds 50MPa, and the impact at thickness 1 / 4 and thickness 1 / 2 is poor, all of which are outside the embodiment of the present application; in comparative example 4, the composite billet process is not used for rolling, the unit weight of the steel plate is small, the compression ratio is small, and the final cooling temperature of the second cooling is high, the yield and tensile strength of the steel plate are significantly reduced, and the impact value of thickness 1 / 4 and thickness 1 / 2 and the cross-sectional shrinkage rate in the thickness direction are poor.

[0073] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to 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 the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing heavy steel for wind power generation, characterized in that: The method comprises: Performing a first heating and a first rolling on at least two first steel billets having set chemical compositions to obtain corresponding second steel billets; Compounding all the corresponding second steel billets to obtain a composite steel billet; The composite steel billet is subjected to second heating and second rolling to obtain a hot-rolled plate; The hot-rolled plate is subjected to a first cooling, a normalizing and a second cooling to obtain a high unit weight steel for wind power generation.

2. The method according to claim 1, characterized in that The first heating temperature is 1210°C to 1250°C.

3. The method according to claim 1, characterized in that The process parameters of the first rolling include: the single-pass reduction rate of the last two passes is ≥10%, and the rolling speed is 1.0 m / s to 1.2 m / s.

4. The method according to claim 1, characterized in that: The second heating temperature is 1120°C to 1160°C.

5. The method according to claim 1, characterized in that The process parameters of the second rolling include: the single-pass reduction rate of the last two passes is ≥20%, the rolling speed is 1.0m / s to 1.2m / s, and the final rolling temperature is ≥980°C.

6. The method according to claim 1, characterized in that The process parameters of the first cooling include: a cooling rate of 10°C / s to 20°C / s, and a final cooling temperature of 600°C to 660°C.

7. The method according to claim 1, characterized in that The normalizing temperature is 875°C to 885°C.

8. The method according to claim 1, characterized in that The process parameters of the second cooling include: a cooling rate of 5°C / s to 12°C / s, and a final cooling temperature of 530°C to 600°C.

9. The method according to claim 1, characterized in that: The set chemical composition includes: C, Si, Mn, Alt, Nb, Ti, V, Cu, P, S and Fe; wherein, in terms of mass fraction, The C content is 0.16% to 0.18%, the Si content is 0.40% to 0.50%, the Mn content is 1.50% to 1.60%, the Alt content is 0.02% to 0.05%, the Nb content is 0.015% to 0.025%, the Ti content is 0.01% to 0.02%, the V content is 0.03% to 0.06%, the Cu content is 0.2% to 0.3%, the P content is 0.01% to 0.02%, and the S content is <0.003%.

10. A high unit weight steel for wind power produced by the method according to any one of claims 1 to 9, characterized in that: The heavy unit weight wind power steel meets the following properties: yield strength at different thickness positions ≥390MPa, yield strength difference at different thickness positions ≤50MPa; tensile strength ≥530MPa, tensile strength difference at different thickness positions ≤30MPa; impact value ≥120J; section shrinkage in thickness direction ≥45%.

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