A kind of non-homogeneous high-strength crack arrest resistant structural steel plate and its manufacturing method

Abstract

The invention discloses a non-homogeneous high-strength crack arrest resistant structural steel plate and a manufacturing method thereof. A high-performance steel plate with a bainite structure is obtained by adopting a specific chemical composition design and a steel plate modulation process. The purity of the steel is further improved by smelting and continuous casting control technology, internal defects such as segregation and looseness are eliminated, non-metallic inclusions are reduced, and the cast structure is homogenized, so that the steel plate has large thickness, high strength and toughness, non-homogeneity, high mold weldability and excellent crack arrestability, and its yield ratio is 0.69-0.74, and the safety performance is high. Therefore, the structural steel plate of the invention can be used for the production of steel structures such as bridges and high-rise buildings, and effectively solves the problem that conventional steel materials cannot meet the demand for wind power steel due to insufficient strength and crack arrest resistance.

Description

Technical Field

[0001] The present disclosure relates to the field of ferrous metal materials, and in particular to high-strength crack-arresting structural steel and a manufacturing method thereof. Background Art

[0002] With the development of wind turbine construction in China, many regions with stable wind power and vast geographical areas are vigorously building wind turbines. Since wind power has always been in an operational cycle, conventional steel materials are prone to breakage during use, so the demand for crack-resistant steel for wind power continues to increase.

[0003] The load-bearing parts of the main body of wind power are mostly steel structures. Under the continuous promotion of wind energy loads, the steel plates themselves are very prone to fatigue fracture, which will greatly affect the safe service of the steel structure. In recent years, the call for the minimum maintenance of wind power steel structures has been increasing, and the demand for improving wind power steel through high strength and crack resistance is very urgent. For example, CN101987330A discloses "a method for manufacturing ultra-thick anti-laminated tearing steel plates", which includes smelting, ingot casting, forging, rolling, and heat treatment to produce anti-laminated tearing steel plates with a thickness of 130 to 400 mm. It is characterized in that a forging process is provided between the ingot casting process, and the steel ingot is forged into a steel plate blank and subjected to post-forging heat treatment. The initial forging temperature of the forging process is 1225 to 1250 ° C, the final forging temperature is 850 to 900 ° C, and the compression ratio is not less than 3. Its disadvantage is that the casting adopts die casting and forging, which is more expensive than the current mature slab continuous casting method.

[0004] CN 109797342 A discloses a high-strength, high-toughness, atmospheric corrosion-resistant steel plate for steel structure production and a manufacturing method thereof, wherein the element composition wt% is: C: 0.03-0.10%, Si: 0.30-0.50%, Mn: 1.10-1.50%, P<0.010%, S<0.003%, Cr: 0.45-0.70%, Cu: 0.25-0.40%, Ni: 0.30-0.40%, Alt: ≥0.030%, Ti: 0.006~0.030%, V: 0.040~0.080%, Mo: 0.02~0.08%, Ca: 0.0010~0.0030%, N: 0.0020~0.0080%, B: 0.0002~0.0030%, Ce: 0.001~0.010%, atmospheric corrosion resistance index I>6.5, CEV<0.54, Pcm<0.27, the balance is Fe and inevitable impurities. However, the disadvantages of this invention patent application are that the steel plate does not have a low yield strength ratio, poor safety performance, and adopts a quenching and tempering heat treatment process, which increases the production cost; the carbon equivalent is too high, the welding performance is poor, and quenching and tempering treatment is required, and the process is complicated.

[0005] CN101343685 discloses a controlled rolling and controlled cooling and normalizing controlled cooling production method for 420MPa grade construction steel plates, but it requires the Nb content to reach 0.03% or more to meet the corresponding mechanical properties. Its purpose is to expand the temperature of the non-recrystallization zone through high Nb and increase the finishing rolling temperature. This method is beneficial to controlling the shape of the steel plate, but after the finishing temperature is increased, the ultra-fast cooling effect will be weakened, which is not conducive to the core of the steel plate to quickly pass through the austenite zone to reach the phase change zone, and thus is not conducive to the precipitation of Nb in the core of the steel plate during the phase change process. This process is not conducive to the production of thick steel plates. Summary of the invention

[0006] In view of this, the present disclosure provides a non-homogeneous high-strength crack-arresting resistant structural steel plate to solve the problem that conventional steel materials cannot meet the demand for steel for wind power due to insufficient strength and crack-arresting resistance.

[0007] In addition, the present disclosure also provides a method for manufacturing a heterogeneous high-strength crack arrest resistant structural steel plate.

[0008] In the first aspect, the chemical composition of the heterogeneous high-strength anti-cracking structural steel plate is as follows by weight percentage:

[0009] C: 0.09%-0.15%, Mn: 1.01%-1.39%, P≤0.010%, S: 0.005%-0.015%, Cr: 0.001%-0.020%, Ni: 0.2%-0.9%, Mo: 0.08%-0.75%, Cu: 0.002%-0.040%, Nb: 0.002%-0.050%, V: 0.001%-0.029%, Ti: 0.001%-0.029%, N: 0.001%-0.030%, Ca: 0.01%-0.035%, Ce: 1ppm-15ppm, La: 1ppm-15ppm, B: 0-0.0010%, the balance is Fe and unavoidable impurities.

[0010] In a second aspect, the method for manufacturing the heterogeneous high-strength anti-cracking structural steel plate described in the first aspect comprises smelting, continuous casting, heating of the ingot, rolling and rapid cooling steps, wherein:

[0011] In the smelting process, molten steel is smelted in a converter, scrap steel and molten iron are used as raw materials, and the molten iron content is controlled at 50-80%; reducing slag is made in an LF refining furnace, and the thickness of the lower slag layer is 100-150 mm; degassing is completed in an RH furnace, the net cycle time is 16-21 minutes, the vacuum degree is 40-65 Pa, the calming time before pouring is 3-9 minutes, and the gas hydrogen content is controlled to be ≤0.0001%, the oxygen content is ≤0.0012%, and the nitrogen content is ≤0.0015.

[0012] In the present disclosure and possible embodiments, in the continuous casting process, the superheat of the tundish is controlled at 25-40°C, the secondary cooling water temperature is 20-30°C, the flow rate is 160-250t / h, and the crystallizer cooling water temperature is 15-25°C, and the flow rate is 160-230t / h.

[0013] In the present disclosure and possible embodiments, a heavy pressure reduction method is adopted at the end of continuous casting, the pressure reduction amount is 20 to 30 mm, and the billet drawing speed is controlled to be 0.6 to 1.2 m / min; the thickness of the continuous casting billet is 200 to 360 mm, and the billet is stacked and slowly cooled for more than 24 hours after leaving the line.

[0014] In the present disclosure and possible embodiments, in the casting heating process, the grinding and anti-oxidation coating-sprayed casting is sent into a walking beam heating furnace for heating, and the thickness of the spraying is 0.9-1.5 mm;

[0015] The ingot is processed in the preheating section, the heating section and the soaking section in sequence and then taken out of the furnace;

[0016] The temperature range of the preheating section is 700-850°C; the temperature range of the heating section is 850-1230°C; the temperature range of the soaking section is 1180-1250°C;

[0017] The soaking time of the cast billet in the heating furnace is controlled to be 3-6 hours.

[0018] In the present disclosure and possible embodiments, in the rolling process, two-stage controlled rolling is adopted, the first stage rolling temperature is 1100-1200°C, and the average reduction rate of the first 4 passes is controlled at 15-25%; the second stage rolling temperature is 970-1030°C, and the average reduction rate of the last 5 passes is 2-5%; the final rolling temperature is 940-990°C, and the thickness of the steel plate after rolling is 16-80mm.

[0019] In the present disclosure and possible embodiments, in the rapid cooling process, the initial cooling temperature of the steel plate after rolling is 730-770°C, the final cooling temperature is 500-550°C, and the cooling rate is 20-31°C / s;

[0020] After the steel plate is cooled, the side spray is turned on, the side spray pressure is 2-7MPa, and the side spray water volume is 55-83m3 / h;

[0021] Two passes of straightening are performed by hot straightening, with the lead-in roller position at 1.0mm-1.9mm and the lead-out roller position at 2.6mm-3.5mm.

[0022] The present invention has the following beneficial effects:

[0023] The heterogeneous high-strength crack-arresting resistant structural steel plate of the present invention adopts a specific chemical composition design and a steel plate modulation process to obtain a high-performance steel plate with a bainite structure. The steel purity is further improved through smelting and continuous casting control technology, internal defects such as segregation and looseness are eliminated, non-metallic inclusions are reduced, and the cast structure is homogenized. The non-metallic inclusions of Class A are ≤0.5, Class B are ≤0.5, Class C are ≤0.5, Class D are ≤0.5, and the total non-metallic inclusions are ≤1.0; the gas hydrogen content is ≤0.0001%, the oxygen content is ≤0.0012%, and the nitrogen content is ≤0.0015. ; The center porosity of the continuous casting billet is ≤1.0, the center crack is ≤1.0, the fine grain ratio of the continuous casting billet is 8-15%, and the equiaxed grain ratio is 15-25%; it has a large thickness (80-120mm), a yield strength ≥407MPa, a tensile strength ≥570MPa, and an elongation ≥20%; -35℃ impact energy ≥53J, ferrite content: 25-40%, -20℃ CTOD ≥0.45mm, high strength and toughness, heterogeneity, high mold weldability and excellent crack arrest performance, and its yield strength ratio is 0.69-0.74, with high safety performance; so the structural steel plate of the present invention can be used in the manufacture of steel structures such as bridges and high-rise buildings, effectively solving the problem that conventional steel materials cannot meet the demand for wind power steel due to insufficient strength and crack arrest resistance. DETAILED DESCRIPTION

[0024] The present disclosure is described below based on embodiments, but it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, some specific details are described in detail. However, for the parts that are not described in detail, those skilled in the art can also fully understand the present disclosure.

[0025] At the same time, unless the context clearly requires otherwise, the words "include", "comprises" and similar words throughout the specification and claims should be interpreted as inclusive rather than exclusive or exhaustive; that is, the meaning is "including but not limited to".

[0026] The following embodiments of the present disclosure adopt the following composition design and process design to manufacture the heterogeneous high-strength anti-cracking structural steel plate of the present invention, as follows:

[0027] 1. Ingredient Design

[0028] The chemical composition of the heterogeneous high-strength anti-crack structural steel plate of the following embodiment of the present invention is as follows by weight percentage:

[0029] C: 0.09%-0.15%, Mn: 1.01%-1.39%, P≤0.010%, S: 0.005%-0.015%, Cr: 0.001%-0.020%, Ni: 0.2%-0.9%, Mo: 0.08%-0.75%, Cu: 0.002%-0.040%, Nb: 0.002%-0.050%, V: 0.001%-0.029%, Ti: 0.001%-0.029%, N: 0.001%-0.030%, Ca: 0.01%-0.035%, Ce: 1ppm-15ppm, La: 1ppm-15ppm, B: 0-0.0010%, the balance is Fe and unavoidable impurities.

[0030] The reasons for adopting the above-mentioned composition design are as follows:

[0031] (1) Carbon: In order to ensure that the steel plate has polygonal ferrite and acicular ferrite, a considerable carbon content is required. At the same time, carbon can form carbides with alloy elements such as Nb and Cr to increase strength and toughness. If the carbon content is too high, the low-temperature toughness will decrease. In order to ensure that the steel plate has high strength and toughness and good crack arrestability, the present invention C: 0.09%-0.15%

[0032] (2) Manganese: It improves the strength of steel in the form of solid solution strengthening and makes up for the deficiency caused by the reduction of C. It is the main alloying element that affects strength, hardenability and weldability. It is also low in cost. However, if the content is too high, it is easy to cause segregation in the formation center and will also have an adverse effect on the weldability of steel. Therefore, the control range is set to 1.01%-1.39%.

[0033] (3) P and S: Both are harmful elements in the steel of the present invention, which have an adverse effect on the low-temperature impact toughness and lamellar tearing resistance of the steel plate and increase the brittleness of the steel. Phosphorus reduces welding performance, reduces plasticity, and deteriorates cold bending performance; sulfur reduces the ductility and toughness of steel and causes cracks during forging and rolling. Therefore, the lower the content, the better. However, considering the steelmaking conditions and costs, the present invention requires that P in the steel be controlled to be ≤ 0.010%, and S: 0.005%-0.015%.

[0034] (4) Chromium: Cr is an important element of austenitic stainless steel. Cr is the main element for improving the high temperature oxidation resistance and high temperature corrosion resistance of steel plates. It is also a key element for forming M23C6 carbides. However, excessive addition of Cr will lead to coarsening of carbides, thereby reducing the high temperature strength and toughness of the steel plate. In the present invention, the Cr content is controlled at 13.9%-16.9%.

[0035] (5) Nickel: Ni can effectively improve the low-temperature toughness of steel, improve the hot brittleness caused by copper in steel, and improve the isotropy of steel plates. However, adding a large amount of nickel will sharply increase the cost and affect the welding performance. According to the performance requirements, the appropriate amount is added. The content of Ni in the present invention is controlled at 0.2%-0.9%.

[0036] (6) Molybdenum: A strong hardenability element, which helps thick steel plates to be hardened along the thickness direction, improves the performance stability of the steel plates, and allows the steel plates to be tempered at a higher temperature, thereby improving the plasticity and toughness of the steel plates; it can increase the solubility of microalloying elements in austenite, reduce the precipitation of carbonitrides of microalloying elements, and allow the microalloying elements to precipitate from ferrite at a lower temperature, thereby enhancing the precipitation strengthening effect. Therefore, the present invention requires Mo: 0.08%-0.75%.

[0037] (7) Copper: Cu is an austenite-forming element. At the same time, the support of copper in the core of the steel plate can compensate for the loss of strength due to increased thickness. Cu: 0.002%-0.040%.

[0038] (8) Niobium: As a strong carbide-forming element, it forms a NbC phase with large dispersion and good high-temperature stability in steel, which plays a role in precipitation strengthening. Through multi-stage rolling, it can effectively refine the grains and improve the reduction in toughness caused by precipitation strengthening, so that the steel plate can obtain the comprehensive performance of high strength and high toughness. In addition, in steel with Nb-Mo composite addition, Mo can also be concentrated on the NbC matrix interface, preventing the coarsening of NbC particles, thereby greatly improving the high-temperature strength of the steel. Therefore, the Nb content is controlled at 0.002%-0.050%.

[0039] (9) Vanadium: The present invention adds a large amount of vanadium, mainly to utilize it to form stable refractory carbides with carbon and nitrogen, so that the steel can still maintain a fine-grained structure at high temperatures, thereby ensuring the high-temperature performance of the steel. In addition, since vanadium fixes carbon in vanadium carbides, the hydrogen resistance of the steel under high temperature and high pressure is greatly improved. V: 0.001%-0.029%.

[0040] (10) Titanium: It can play a nitrogen fixing effect, forming a precipitate phase mainly composed of TiN, which can inhibit the grain growth of austenite under high temperature conditions and improve the toughness of the heat-affected zone after welding. During the welding process, TiN particles prevent the grain growth of the heat-affected coarse-grained zone and improve the low-temperature toughness of the welded joint. In addition, due to its low solid solubility, Ti is easy to appear in the form of interphase precipitation during the transformation from austenite to ferrite, thereby improving the strength. However, too much Ti will reduce the toughness of the steel, so the Ti content is controlled at 0.001%-0.029%.

[0041] (11) Nitrogen: N forms nitrides with elements such as Nb, V, and Ti, precipitates at grain boundaries, pins the grain boundaries and refines the grains, thus improving the high-temperature strength of the grain boundaries. N: 0.001%-0.030%.

[0042] (12) Calcium: Calcium plays a certain role in deoxidation during steelmaking, and is also beneficial for grain refinement, and can improve lamellar tear resistance and fatigue strength. Therefore, the present invention requires Ca: 0.01%-0.035%.

[0043] (13) Cerium: The element undergoes inclusion modification during the smelting process and is modified into soft and fine inclusions. The fine rare earth inclusions can serve as nucleation points for high-temperature ferrite, refine the dendrite structure, and thereby reduce microsegregation, reduce the size of primary carbides, and make the distribution of primary carbides more uniform. Therefore, the present invention requires that the Ce content in the steel be 1ppm-15ppm.

[0044] (14) Lanthanum: purifies steel and causes inclusions in steel to deteriorate, thus improving the purity of steel; has a certain hydrogen capture capacity, reducing defects such as white spots in ultra-thick plates; the precipitates formed can serve as a nucleation basis, thereby playing a role in fine grain strengthening, so the content of La in the present invention is 1ppm-15ppm

[0045] (15) Boron: Boron can reduce the transformation temperature from austenite to ferrite phase, promote the formation of acicular ferrite in the grains, and play a role in refining the grains. Therefore, its content in the present invention is B: 0-0.0010%.

[0046] 2. Process Design

[0047] (1) Smelting process: The molten steel is smelted in a converter, using high-quality scrap steel and molten iron as raw materials. The molten iron content is controlled at 50-80%. The reducing slag is made in the LF refining furnace, and the thickness of the lower slag layer is 100-150 mm to ensure that the inclusions float fully. Degassing is completed in the RH furnace, with a net cycle time of 16-21 minutes, a vacuum degree of 40-65 Pa, and a calming time of 3-9 minutes before pouring. The gas hydrogen content is strictly controlled to be ≤0.0001%, the oxygen content is ≤0.0012%, and the nitrogen content is ≤0.0015. This smelting process design can effectively reduce rolling in steel and reduce the formation of non-metallic inclusions in steel.

[0048] (2) Continuous casting process: During the casting process, the superheat of the tundish is controlled at 25-40°C, the secondary cooling water temperature is 20-30°C, the flow rate is 160-250t / h, the crystallizer cooling water temperature is 15-25°C, the flow rate is 160-230t / h, and at the end of the continuous casting, a heavy pressure reduction method is adopted with a pressure reduction of 20-30mm, and the billet drawing speed is controlled at 0.6-1.2m / min.

[0049] The method of the present invention can control the crystallization process of each stage through the above-mentioned smelting and continuous casting control process design, ensure the rapid transformation of columnar crystals and equiaxed crystals, develop columnar crystals in the continuous casting billet, and reduce the generation of equiaxed crystals in the center, so that carbides are easy to gather at the junction of columnar crystals and equiaxed crystals during the solidification of the continuous casting billet. At the same time, the reduction of equiaxed crystals can reduce the degree of central segregation to a certain extent, and the Z-direction performance of the steel plate after rolling can also be improved. Finally, it can be obtained that the proportion of fine crystals in the casting billet is 8-15%, and the proportion of equiaxed crystals is 15-25%. This grain ratio control can effectively improve the as-cast structure and improve the uniformity of the structure, laying a foundation for the steel plate to obtain excellent performance. The preferred thickness of the continuous casting billet is 200-360mm, and the stacking and slow cooling are performed for more than 24 hours after the billet is off the line, which further promotes the homogenization of the structure and precipitates and reduces the component segregation.

[0050] (3) Heating of ingots: The ingots that have been ground and sprayed with anti-oxidation coating are sent to a step-beam heating furnace for heating. The spraying thickness is 0.9-1.5mm. The ingots are processed in the preheating section, heating section and soaking section in turn before being taken out of the furnace. The temperature range of the preheating section is 700-850℃; the temperature range of the heating section for all thicknesses is 850-1230℃; the temperature range of the soaking section is 1180-1250℃. The soaking section time of the ingot in the heating furnace is controlled at 3-6 hours, which can effectively ensure the uniformity of heating inside the steel plate and the thickness of the decarburized layer on the surface of the steel plate is ≤20μm. The reduction of the decarburized layer can avoid the formation of ultrafine ferrite on the surface during rapid cooling due to the reduction of carbon content, and can reduce the strength of the steel plate surface to ensure the uniformity of the steel plate strength.

[0051] The present invention has a great influence on rolling through the surface spraying and dephosphorization process of the billet. Too high temperature will cause serious oxidation and decarburization of the cast billet. The surface spraying of the continuous casting billet can effectively reduce the thickness of the decarburization layer to ≤20μm, ensuring the stability and uniformity of the surface structure of the steel plate. The two-way dephosphorization technology can ensure the improvement of the quality of the steel plate and avoid the generation of surface defects of unidirectional dephosphorization.

[0052] (4) Rolling process: The steel plate rolling adopts two-stage controlled rolling. The first stage rolling temperature is 1100-1200℃, and the average reduction rate of the first 4 passes is controlled at 15-25%. Low temperature plastic deformation promotes dynamic recrystallization and increases deformation resistance to break grains. The second stage rolling temperature is 970-1030℃, and the last 5 passes adopt small deformation, with an average reduction rate of 2-5%, which is conducive to eliminating the rolling orientation of grains. The final rolling temperature is 940-990℃. The thickness of the steel plate after rolling is 16-80mm.

[0053] (5) Rapid cooling process: After the steel plate is rolled, the start cooling temperature is 730-770°C, the final cooling temperature is 500-550°C, the cooling rate is controlled at 20-31°C / s, the side spray is turned on after the steel plate is cooled, the side spray pressure is 2-7MPa, the side spray water volume is 55-83m3 / h, and then two passes of straightening are performed through hot straightening, the lead-in roller position is 1.0mm-1.9mm, and the lead-out roller position is 2.6mm-3.5mm;

[0054] Example

[0055] 1. Composition design and process design of embodiments 1-10 of the present disclosure

[0056] 1. The steel plate composition design of Examples 1-10 of the present disclosure is shown in Table 1:

[0057] Table 1 Chemical composition of steel in each example (wt%)

[0058]

[0059] 2. The smelting processes used in Examples 1-10 of the present disclosure are shown in Table 2:

[0060] Table 2 Smelting process system of example steel

[0061]

[0062]

[0063] 3. The continuous casting process used in Examples 1-10 of the present disclosure is shown in Table 3:

[0064] Table 3 Continuous casting process parameters of the embodiment

[0065]

[0066] 4. The continuous casting billet heating process used in Examples 1-10 of the present disclosure is shown in Table 4:

[0067] Table 4 Continuous casting slab heating process parameters

[0068] Example Thickness of ingot / mm Spraying thickness / mm Preheating temperature / ℃ Heating section temperature / ℃ Soaking section temperature / ℃ Soaking time / h 1 200 0.90 700 850 1180 5.6 2 220 0.95 710 900 1190 3.3 3 240 1.00 730 1000 1200 4.5 4 260 1.10 750 1100 1210 3.9 5 280 1.15 760 1200 1220 4.2 6 300 1.20 780 880 1230 3.6 7 320 1.30 800 950 1240 4.8 8 340 1.35 820 1050 1250 5.1 9 350 1.45 835 1150 1235 3.0 10 360 1.50 850 1230 1245 6.0

[0069] 5. The rolling process used in Examples 1-10 of the present disclosure is shown in Table 5:

[0070] Table 5 Rolling process of example steel

[0071]

[0072] 6. The rapid cooling process used in Examples 1-10 of the present disclosure is shown in Table 6:

[0073] Table 6 Rapid cooling process of example steel

[0074]

[0075] II. Comparison of quality and performance of Examples 1-10 and comparative steels of the present disclosure

[0076] 1. The internal quality evaluation of Examples 1-10 and the comparative steels of the present disclosure is shown in Table 7:

[0077] Table 7 Non-metallic inclusions and low-power rating of continuous casting billets in the examples and comparative steels

[0078]

[0079] It can be seen from Table 7 that the non-metallic inclusions of the steel plates made in each embodiment are Class A ≤ 0.5, Class B ≤ 0.5, Class C ≤ 0.5, Class D ≤ 0.5, and the total non-metallic inclusions ≤ 1.0; the center looseness of the continuous casting billet is ≤ 1.0, and the center crack is ≤ 1.0.

[0080] 2. The performance evaluation of Examples 1-10 of the present disclosure and the comparative steel (Q420ME) is shown in Table 8:

[0081] Table 8 Performance of Examples and Comparative Steels

[0082]

[0083]

[0084] It can be seen from Table 8 that the average mechanical properties of the steel plates made in each embodiment are: yield strength ≥407MPa, tensile strength ≥570MPa, elongation ≥20%; -45℃ impact energy ≥53J, ferrite content: 25-40%, -20℃ CTOD ≥0.45mm.

[0085] The above-described embodiments are only embodiments of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the present disclosure. It should be noted that, for a person of ordinary skill in the art, without departing from the concept of the present disclosure, several variations, equivalent substitutions, improvements, etc. may be made, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the attached claims.

Claims

1. A non-homogeneous high-strength crack arrest resistant structural steel plate, characterized in that: Its chemical composition by weight percentage is: C: 0.09%-0.149%, Mn: 1.01%-1.39%, P≤0.010%, S: 0.005%-0.015%, Cr: 0.001%-0.020%, Ni: 0.2%-0.9%, Mo: 0.08%-0.75%, Cu: 0.002%-0.040%, Nb: 0.002%-0.050%, V: 0.001%-0.029%, Ti: 0.013%-0.029%, N: 0.020%-0.030%, Ca: 0.024%-0.035%, Ce: 1ppm-15ppm, La: 1ppm-15ppm, B: 0.00060-0.0010%, the balance is Fe and unavoidable impurities; The manufacturing method of the heterogeneous high-strength anti-cracking structural steel plate includes smelting, continuous casting, billet heating, rolling and rapid cooling; In the smelting process, molten steel is smelted in a converter, scrap steel and molten iron are used as raw materials, and the molten iron content is controlled at 50-80%; reducing slag is made in an LF refining furnace, and the thickness of the lower slag layer is 100-150 mm; degassing is completed in an RH furnace, the net cycle time is 16-21 minutes, the vacuum degree is 40-65 Pa, the calming time before pouring is 3-9 minutes, and the gas hydrogen content is controlled to be ≤0.0001%, the oxygen content is ≤0.0012%, and the nitrogen content is ≤0.0015; In the continuous casting process, the tundish superheat is controlled at 25-40°C, the secondary cooling water temperature is 20-30°C, the flow rate is 160-250t / h, and the crystallizer cooling water temperature is 15-25°C, and the flow rate is 160-230t / h. At the end of continuous casting, heavy pressure is used, the pressure reduction is 20-30mm, and the billet drawing speed is controlled to be 0.6-1.2m / min; the thickness of the continuous casting billet is 200-360mm, and the billet is stacked and slowly cooled for more than 24 hours after it comes off the line; In the casting heating process, the grinding and anti-oxidation coating-sprayed casting is sent into a walking beam heating furnace for heating, and the thickness of the spraying is 0.9-1.5 mm; The ingot is processed in the preheating section, the heating section and the soaking section in sequence and then taken out of the furnace; The temperature range of the preheating section is 700-850°C; the temperature range of the heating section is 850-1230°C; the temperature range of the soaking section is 1180-1250°C; The soaking time of the cast billet in the heating furnace is controlled to be 3-6 hours; In the rolling process, two-stage controlled rolling is adopted, the first stage rolling temperature is 1100-1200°C, and the average reduction rate of the first 4 passes is controlled at 15-25%; the second stage rolling temperature is 970-1030°C, and the average reduction rate of the last 5 passes is 2-5%; the final rolling temperature is 940-990°C, and the thickness of the steel plate after rolling is 16-80mm; In the rapid cooling process, the initial cooling temperature of the steel plate after rolling is 730-770°C, the final cooling temperature is 500-550°C, and the cooling rate is 20-31°C / s; After the steel plate is cooled, the side spray is turned on, the side spray pressure is 2-7MPa, and the side spray water volume is 55-83m3 / h; Two passes of straightening are performed by hot straightening, with the lead-in roller position at 1.0mm-1.9mm and the lead-out roller position at 2.6mm-3.5mm.

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