A saw blade steel and a manufacturing method with low breakage rate

Abstract

The application discloses a saw blade steel and a low-breaking-rate manufacturing method, and belongs to the technical field of metallurgical saw blade steel production. The chemical components of the saw blade steel include the following in percentage by weight: C 0.4%-0.5%, Si 0.2%-0.35%, Mn 0.9%-1.20%, Cr 0.2%-0.35%, B 0.001%-0.0025%, Ca 0.005%-0.010%, P≤0.025%, S≤0.015%, H≤0.02%, the balance of Fe and inevitable impurities, and the total amount of other impurity elements is less than 0.05%. The manufacturing method comprises the following steps: smelting of molten steel, secondary refining, calcium treatment, continuous casting, slab heating, rolling, cooling and straightening. The breaking rate of the continuous casting slab is controlled within 0.1%.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical saw blade steel production technology, specifically relating to a manufacturing method for saw blade steel with low fracture rate. Background Technology

[0002] With the rapid development of mining, stone processing, and construction in my country, the demand for saw blade steel is increasing daily. 45# steel is a high-quality carbon structural steel with excellent strength, but its disadvantages include low hardness and poor wear resistance, resulting in lower-quality saw blade steel. Steels such as 65Mn, 70Mn, DJ100, 75Cr1, and 8CrV, with a carbon content generally between 0.65% and 0.85%, possess high strength, high hardness, and high wear resistance. However, since its production began, saw blade steel often experiences transverse fractures during the hot delivery, slow cooling, or heating of continuously cast billets (150-200mm thick) before rolling. This results in low billet yield, and can even lead to production stoppages and safety accidents, while also affecting delivery times. Currently, the billet fracture rate exceeds 20%, severely impacting contract delivery. Analysis of billet fracture revealed that the fracture originates from the proportion of primary dendrite boundaries in columnar crystals at a distance of 1 / 4 of the surface thickness and the formation of inclusions. However, despite improvements in existing steelmaking and continuous casting processes, the billet fracture rate still exceeds 10%. Therefore, addressing billet fracture, reducing billet scrap rates, and lowering production costs are crucial for the mature and stable development of saw blade steel.

[0003] Compared with existing technologies:

[0004] To date, there are very few reports, both domestically and internationally, on methods for controlling the fracture of continuously cast saw blade steel billets. Prior to this invention, application number CN201910337651.2 disclosed a saw blade steel plate and its production method. This method mainly focuses on producing composite saw blade steel through metallurgical composite rolling, which enables the saw blade steel plate to have high durability and a longer service life when subjected to external load impacts. However, it does not propose a solution to the cracking of the saw blade steel billet, and the production cost is relatively high. Application number CN202210122541.6 discloses a high-carbon manganese-chromium saw blade steel and its production method. The chemical composition of this patent, by mass percentage, includes: C: 0.71-0.82%, Si: 0.20-0.30%, Mn: 0.62-1.21%, Cr: 0.20-0.80%, Al: 0.02-0.08%, O≤0.0015%, P≤0.020%, S≤0.012%. This method uses a high-basicity refining slag system and an aluminum-containing deoxidation process in an LF refining furnace to finally produce a high-carbon manganese-chromium saw blade steel with a tensile strength ≥1000MPa and an elongation A ≥12%, which can be used to cut materials such as wood and marble. However, it does not analyze the cracking method of the saw blade steel billet and propose a solution. Moreover, the produced specification is a coil plate with a narrow rolling width (≤2000mm).

[0005] While the saw blade steel production methods disclosed in the above patent documents achieve high strength and toughness, they mainly focus on the production process of coiled plates or composite plates, and do not solve the problem of high-carbon steel billet fracture rate. Using the technical solution provided by this invention, the above shortcomings can be effectively overcome, enabling the manufacture of saw blade steel with the same performance indicators as typical grades 65Mn, 70Mn, DJ100, 75Cr1, and 8CrV using continuously cast billets with a thickness of 130-170mm. The fracture rate of the continuously cast billets is controlled within 0.1%, reducing the production cost of saw blade steel and improving the contract delivery cycle. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned technical problems and deficiencies, and to provide a saw blade steel and a manufacturing method with low fracture rate, so as to achieve the same performance index as typical grades 65Mn, 70Mn, DJ100, 75Cr1 and 8CrV by using a billet with a thickness of 150-170mm, and to control the billet fracture rate to within 0.1%.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A type of saw blade steel, the chemical composition of which by weight percentage includes: C 0.4%–0.5%, Si 0.2%–0.35%, Mn 0.9%–1.20%, Cr 0.2%–0.35%, B 0.001%–0.0025%, Ca 0.005%–0.010%, P≤0.025%, S≤0.015%, H≤0.02%, with the balance being Fe and unavoidable impurities, and the total amount of other impurity elements being less than 0.05%.

[0009] The roles of the main elements in the chemical composition of the steel plate of this invention are as follows:

[0010] C: Carbon is one of the basic elements in steel. A lower carbon content is beneficial for improving the product's plasticity. However, too low a carbon content is detrimental to strength improvement and subsequent heat treatment. Too high a carbon content increases the risk of billet fracture; therefore, a carbon content of 0.4%-0.5% is selected.

[0011] Mn: Manganese is a solid solution strengthening element. It improves the stability of austenite and enhances the strength and plasticity of steel. However, a low manganese-to-sulfur ratio poses a quality risk in continuous casting production. Therefore, the manganese content should be controlled between 0.9% and 1.20%.

[0012] Si: Silicon is the main element in steel. The silicon content must reach a certain level to ensure the yield strength of steel. However, if the silicon content is too high, the iron oxide scale formed on the surface in the heating furnace is difficult to remove, thus affecting the surface quality of the steel. Therefore, the silicon content in steel is controlled at 0.2%-0.35%.

[0013] P: Phosphorus in steel is a harmful element, and the lower the better. However, considering that the manufacturing cost will increase if the phosphorus content in steel is too low, it is required that P ≤ 0.025%.

[0014] S: Sulfur in steel is a harmful element, and the lower the better. However, considering that the manufacturing cost will increase if the sulfur content in steel is too low, it is required that S≤0.015%.

[0015] Cr: Chromium can increase the hardness of steel, making it more wear-resistant, but an increase in chromium content will lead to an increased risk of brittle fracture. Therefore, the chromium content can be controlled between 0.2% and 0.35%.

[0016] B: Boron can significantly improve the hardenability of steel, while also increasing its hardness and tensile strength. However, excessive boron can lead to a decrease in toughness. Therefore, the boron content should be controlled between 0.001% and 0.025%.

[0017] Ca: Trace amounts of calcium (Ca) in steel can act as a deoxidizing and desulfurizing agent, improving the morphology of non-metallic inclusions. Adding trace amounts of calcium to carbon steel forms dispersed, thermally stable second-phase calcium-containing oxide particles. These dispersed calcium-containing oxide particles pin the austenite grain boundary migration in the coarse-grained heat-affected zone (CGHAZ) during welding thermal cycling, limiting austenite grain growth and achieving a finer welded CGHAZ grain size, thereby improving the strength and toughness of the micro-calcium steel welded CGHAZ. However, excessively high levels of Ca can lead to grain boundary segregation, adversely affecting the hardenability and impact toughness of the steel. The optimal range is controlled between 0.005% and 0.010%.

[0018] H: Hydrogen in steel is a harmful element that causes hydrogen embrittlement in steel plates, so the lower the better. However, considering that the manufacturing cost will increase if the hydrogen content in steel is too low, H is required to be ≤0.02%.

[0019] Furthermore, the thickness of the steel used for the saw blade is 6–20 mm.

[0020] Furthermore, the width of the steel used for the saw blade is 2200-3800mm.

[0021] Furthermore, the steel plate is produced by casting billets on a medium-thickness reciprocating rolling mill, with water as the cooling medium.

[0022] The objective of this invention is achieved through the following technical solution:

[0023] This invention provides a method for manufacturing steel with low fracture rate for saw blades, comprising steel smelting → ladle refining and calcium treatment → continuous casting → billet heating and rolling → cooling and straightening; specifically including the following steps:

[0024] 1) From steelmaking to continuous casting and slow cooling of billet stacking: Steel is smelted according to the following composition, with the following chemical composition by weight percentage: C 0.4%~0.5%, Si 0.2%~0.35%, Mn 0.9%~1.20%, Cr 0.2%~0.35%, B 0.001%~0.0025%, Ca 0.005%~0.010%, P≤0.025%, S≤0.015%, with the balance being Fe and unavoidable impurities, and the total amount of other impurity elements being less than 0.05%. The molten iron undergoes pretreatment, converter smelting, LF refining, continuous casting, and slow cooling in a stack. During LF refining, the use of a Si-Ca wire for ladle refining effectively reduces the oxygen and sulfur content in the molten steel, transforming sulfide and oxide inclusions into calcium-containing spherical inclusions, while also reducing the number of inclusions. This purifies the molten steel, improves steel quality, reduces localized internal stress in the cast billet, and prevents billet fracture. During continuous casting, the electromagnetic stirring current intensity in the secondary cooling zone is controlled at 20... For temperatures ranging from 0 to 250A, the secondary cooling water volume is 2.0 L / kg to 2.3 L / kg (to reduce the average carbon segregation index, suppress segregation, and limit the intensity of secondary cooling to inhibit the tendency of central cracks in the billet to worsen, reduce the proportion of columnar crystals, and control the proportion of columnar crystals to within 5%). After the billet is removed from the production line, it should be stacked for slow cooling. The stacking temperature should not be lower than 600℃, and the slow cooling time should be more than 48 hours (slow cooling of the billet by stacking helps to reduce central segregation of the billet and effectively reduce the internal H content of the billet).

[0025] 2) Billet heating and rolling: The billet is fed into a walking beam furnace for heating. The billet passes through the preheating section, heating section and soaking section in sequence before exiting the furnace. The temperature range of the preheating section is 800-1150℃ (to promote the full diffusion of C, Mn, B and H), the temperature range of the heating section is 1280-1290℃, and the temperature range of the soaking section is 1230-1260℃. The total time in the furnace for the heating and soaking sections is not less than 3-4 hours (to further promote the diffusion of elements such as Mn, C, H and B, reduce their segregation due to composition, reduce internal stress and reduce the risk of billet fracture). The billet is rolled in two stages: the first stage is recrystallization rolling (rough rolling), with an initial rolling temperature range of 1150–1200℃. No more than four rough rolling passes are required, with the first two passes ensuring a reduction rate of over 20%. The resulting intermediate billet thickness is 3.5–4.5 times the finished product thickness (controlling the intermediate billet's preheating thickness and increasing its preheating time promotes dynamic austenite recrystallization, while also increasing the cumulative deformation in the subsequent finishing rolling stage, refining grains, inhibiting crack initiation and propagation, reducing the risk of billet and steel plate fracture, and improving the steel plate's strength and toughness); the second stage is… Non-recrystallization rolling (finish rolling) has an initial rolling temperature range of 910–930℃. The reduction regime in the finishing rolling stage is to ensure a reduction rate of over 20% in the first two passes (to ensure core rolling penetration and promote dynamic recrystallization of austenite grains. In addition, as the reduction gradually increases, the rolled piece undergoes flattening and elongation deformation. At the same time, due to the combined effect of dynamic and static recrystallization, new grains nucleate and grow at the grain boundaries to form new fine recrystallized grains, further inhibiting crack initiation and propagation, reducing the risk of billet and steel plate fracture, and improving the strength and toughness of the steel plate).

[0026] 3) Cooling and Straightening: An ultra-rapid cooling method is adopted, with an initial cooling temperature range of 700–820℃, a cooling rate of 25–50℃ / s during the ultra-rapid cooling stage, and a final cooling temperature range of 100–200℃ (using rapid cooling to ensure the steel plate has a martensitic microstructure, while limiting the final cooling temperature, utilizing the remaining temperature of the steel plate after controlled cooling for short-term self-tempering to improve the steel plate's toughness). After the steel plate exits controlled cooling, side spraying and air purging are activated, with side spray pressure and water flow rate of 2–5 MPa and 150–200 m³ / s, respectively. 3 / h, the air purging pressure is 5~10MPa, straightening is performed, and then air-cooled to room temperature (the use of side spraying, air purging and hot straightening is beneficial to the control of steel plate shape, improves the uniformity of steel plate performance, reduces the probability of problems with the shape of the top and bottom of the plate, and saves the investment cost of subsequent cold straightening equipment).

[0027] Furthermore, the thickness of the cast billet is 150-170 mm.

[0028] Furthermore, in step 1), the raw material is pretreated with KR molten iron to control the S content to be below 0.015%, and then enters the converter after slag removal; during converter smelting, the P content is controlled to be ≤0.025%, and the C content is controlled to be 0.4-0.5% at the end of converter smelting; then LF refining is carried out. During the ladle refining process, argon gas is blown for 5-10 minutes when tapping the steel (argon blowing and calming before continuous casting can promote the removal of inclusions in the molten steel and improve the uniformity of the molten steel composition).

[0029] Furthermore, during the converter smelting process, a double-slag method is used for phosphorus removal.

[0030] Furthermore, in step 1), the continuous casting superheat is 15-20℃, and the continuous casting billet pulling speed is 0.8-1.1m / min.

[0031] Furthermore, in step 2), the billet after exiting the furnace is descaled with high-pressure water for 1 to 2 minutes at a descaling machine pressure of 20 to 25 MPa, and then rolled.

[0032] Furthermore, in step 3), the cooling medium for the ultra-fast cooling method is water.

[0033] Furthermore, in step 3), the straightening is performed in three stages: the inlet roller position is -1.0mm to -2.0mm, and the outlet roller position is -2.6mm to -3.5mm.

[0034] By employing the above-mentioned composition and steel smelting process, including continuous casting, slow cooling of the cast billet, heating, rolling, and cooling, this method overcomes the shortcomings of existing technologies and provides a manufacturing method for a new type of saw blade steel with low fracture rate. It enables the production of new saw blade steel plates with thicknesses of 6–20 mm using continuously cast billets with a thickness of 150-170 mm. The fracture rate of the continuously cast billet is controlled within 0.1%, achieving performance indicators identical to typical grades 65Mn, 70Mn, DJ100, 75Cr1, and 8CrV. Specifically, the transverse tensile yield strength is between 1250 and 1300 MPa, the tensile strength is between 1400 and 1480 MPa, and the elongation is ≥10%. The transverse Charpy impact energy at 0℃ is ≥35 J, and the hardness is between 50 and 60 HRC.

[0035] The beneficial effects of this invention are:

[0036] 1) By employing argon blowing, argon blowing and calming before continuous casting can promote the removal of inclusions in molten steel and improve the uniformity of steel composition. During ladle refining, using Si-Ca wire for ladle refining can effectively reduce the oxygen and sulfur content in the molten steel, transforming sulfide and oxide inclusions into calcium-containing spherical inclusions, while reducing the number of inclusions. This achieves the purpose of purifying the molten steel, improving the quality of the steel, reducing local internal stress in rolled steel plates, and optimizing the electromagnetic stirring current intensity and secondary cooling water ratio in the secondary cooling zone can reduce the average carbon segregation index, suppress segregation, and reduce the proportion of columnar crystals, keeping it below 5%. At the same time, limiting the intensity of secondary cooling can suppress the tendency of central cracks in the billet to worsen. Slow cooling of billet stacking helps reduce central segregation in the billet and effectively reduces the internal H content of the billet.

[0037] 2) By controlling the time and temperature in the soaking and heating sections of the furnace, the high-temperature section and the total time spent in the furnace effectively promote the full diffusion of elements such as C, Mn, H, and B, reducing their segregation due to composition, lowering internal stress, reducing the risk of billet fracture, and improving the hardenability of the rolled steel plate. The composition of this invention is reasonably designed. By reducing the C content and adding B, the fracture rate of the continuously cast billet is controlled within 0.1%, which also improves the hardenability of the steel plate and helps to ensure the comprehensive performance of the super steel plate.

[0038] 3) A two-stage controlled rolling process is adopted to control the reduction in the roughing and finishing passes, ensuring core rolling penetration, optimizing the thickness of the intermediate billet, promoting dynamic recrystallization of austenite, and increasing the cumulative deformation in the subsequent finishing stage to refine the grains, inhibit crack initiation and propagation, reduce the risk of billet and steel plate fracture, and improve the strength and toughness of the steel plate. After rolling, a fast cooling rate is adopted to ensure that the microstructure of the steel plate is martensitic, and the final cooling temperature is limited. The remaining temperature of the steel plate after controlled cooling is used for short-term self-tempering to improve the toughness of the steel plate. The use of side spraying, air blowing and hot straightening is conducive to the control of the steel plate shape, improves the uniformity of steel plate performance, reduces the probability of head and tail shape problems, and saves the investment cost of subsequent cold straightening equipment.

[0039] 4) This invention, through simple composition design, reduces the carbon content and adds boron, and overcomes the shortcomings of existing technologies by controlling the continuous casting, billet slow cooling, heating, rolling, and cooling processes. It achieves a novel saw blade steel manufacturing method with low fracture rate, enabling the production of saw blade steel plates with thicknesses of 6-20mm using continuously cast billets with a thickness of 150-170mm. The fracture rate of the continuously cast billets is controlled within 0.1%, achieving performance indicators similar to typical grades 65Mn, 70Mn, DJ100, 75Cr1, and 8CrV. This reduces saw blade steel production costs and improves contract delivery cycles. Specific properties include: transverse tensile yield strength between 1250-1300MPa, tensile strength between 1400-1480MPa, elongation ≥10%, transverse Charpy impact energy at 0℃ ≥35J, and hardness between 50-60HRC. Detailed Implementation

[0040] The following examples are used to illustrate the content of the present invention. These examples are only general descriptions of the content of the present invention and do not limit the content of the present invention.

[0041] A saw blade steel has the following chemical composition by weight percentage: C 0.4%–0.5%, Si 0.2%–0.35%, Mn 0.9%–1.20%, Cr 0.2%–0.35%, B 0.001%–0.0025%, Ca 0.005%–0.010%, P≤0.025%, S≤0.015%, H≤0.02%, with the balance being Fe and unavoidable impurities, and the total amount of other impurity elements being less than 0.05%. The saw blade steel has a thickness of 6–20 mm, the billet thickness is 150–170 mm, and the steel plate is produced by casting the billet on a medium-thick plate reciprocating rolling mill, with water as the cooling medium.

[0042] The manufacturing method for the aforementioned saw blade steel with low fracture rate includes steel smelting → ladle refining and calcium treatment → continuous casting → billet reheating and rolling → cooling and straightening; specifically, it includes the following steps:

[0043] 1) Steelmaking to continuous casting and slow cooling of billet stacking: Smelting according to the above composition. Raw materials are pretreated with KR hot metal to control the S content below 0.015%, and then fed into the converter after slag removal; during converter smelting, a double-slag method is used to remove P, controlling the P content ≤0.025%, and the C content is controlled at 0.4-0.5% at the end of converter smelting; then LF refining is carried out. During the ladle refining process, argon gas is blown for 5-10 minutes when tapping the steel; during the LF refining process, using a Si-Ca wire for ladle refining can effectively reduce the oxygen and sulfur content in the molten steel, and transform sulfide and oxide inclusions into calcium-containing spherical inclusions. Simultaneously, the number of inclusions is reduced, thereby purifying the molten steel, improving the quality of the steel, reducing local internal stress in the billet, and preventing billet fracture. Then, slab continuous casting is carried out, with a superheat of 15–20℃ and a casting speed of 0.8–1.1 m / min. The electromagnetic stirring current intensity in the secondary cooling zone during continuous casting is controlled at 200–250 A, and the secondary cooling water volume is 2.0 L / kg–2.3 L / kg. After the billet is removed from the production line, it is stacked for slow cooling, with a stack temperature not lower than 600℃ and a slow cooling time of at least 48 hours.

[0044] 2) Reheating and rolling of billet: The billet with a thickness of 150-170mm is fed into a walking beam furnace for heating. The billet passes through the preheating section, heating section and soaking section in sequence before exiting the furnace. The temperature range of the preheating section is 800-1150℃, the temperature range of the heating section is 1280-1290℃, and the temperature range of the soaking section is 1230-1260℃. The total time in the furnace for heating and soaking is not less than 3-4 hours. Before rolling, the billet after exiting the furnace is descaled with high-pressure water for 1-2 minutes, with a descaling machine pressure of 20-25 MPa. The rolling is carried out in two stages: the first stage is recrystallization rolling (rough rolling), with an initial rolling temperature range of 1150-1200℃. The rough rolling is no more than four passes, and the reduction ratio of the first two passes is guaranteed to be above 20%. The thickness of the intermediate billet is 3.5-4.5 times that of the finished product. The second stage is non-recrystallization rolling (finish rolling), with an initial rolling temperature range of 910-930℃. The reduction ratio of the first two passes in the finish rolling stage is guaranteed to be above 20%.

[0045] 3) Cooling and straightening: An ultra-rapid cooling method is adopted, with an initial cooling temperature range of 700–820℃, a cooling rate of 25–50℃ / s during the ultra-rapid cooling stage, and a final cooling temperature range of 100–200℃. After the steel plate exits controlled cooling, side spraying and air purging are activated, with side spray pressure and water flow rate of 2–5MPa and 150–200m³ / h, respectively. 3 / h, the air purging pressure is 5~10MPa, hot straightening (three-stage straightening) is performed, the inlet roller position is -1.0mm~-2.0mm, the outlet roller position is -2.6mm~-3.5mm, and then air-cooled to room temperature.

[0046] Examples 1-6

[0047] Table 1 shows the chemical composition of the steel in the examples; Table 2 shows the smelting, continuous casting, and stacking process of the steel in the examples; Table 3 shows the heating process of the billet and the pre-rolling descaling process of the steel in the examples; Table 4 shows the rolling parameters of the steel in the examples; Table 5 shows the main process parameters for controlled cooling and straightening of the steel in the examples; and Table 6 shows the performance and quality indicators of the steel plates in the examples.

[0048] Table 1 Chemical composition (wt, %) of the steel in the examples

[0049]

[0050] Note: The impurity elements in steel are P≤0.025%, S≤0.015%, and the total amount of other impurity elements is less than 0.05%.

[0051] Table 2. Steel smelting to continuous casting and stacking process regulations in the examples.

[0052]

[0053] Table 3 Heating regime and pre-rolling descaling process for steel billets in the examples

[0054]

[0055] Table 4 Rolling parameters of the steel in the examples

[0056]

[0057] Table 5. Main process parameters for controlled cooling and straightening of steel in the examples.

[0058]

[0059] Table 6 Performance and quality indicators of the steel plates in the examples

[0060]

[0061] Therefore, compared with the existing technology, this invention overcomes the shortcomings of the existing technology by simplifying the composition design, reducing the C content, adding the B element, and controlling the continuous casting, billet slow cooling, heating, rolling, and cooling processes. It provides a manufacturing method for a new type of saw blade steel with low fracture rate, enabling the production of new saw blade steel with a plate thickness of 6-20mm using a continuous casting billet with a thickness of 150-170mm. The fracture rate of the continuous casting billet is controlled within 0.1%, and the performance indicators are the same as those of typical grades 65Mn, 70Mn, DJ100, 75Cr1, and 8CrV. This reduces the production cost of saw blade steel and improves the contract delivery cycle.

[0062] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A type of steel for saw blades, characterized in that, Its chemical composition by weight percentage includes: C 0.4%–0.5%, Si 0.2%–0.35%, Mn 0.9%–1.20%, Cr 0.2%–0.35%, B 0.001%–0.0025%, Ca 0.005%–0.010%, P≤0.025%, S≤0.015%, H≤0.02%, with the balance being Fe and unavoidable impurities, and the total amount of other impurity elements being less than 0.05%. The method for manufacturing steel for saw blades includes the following steps: 1) Steel smelting to continuous casting and billet stacking slow cooling: Molten iron undergoes pretreatment, converter smelting, LF refining, continuous casting, and stacking slow cooling; during LF refining, Si-Ca wire is used for ladle refining; during continuous casting, the electromagnetic stirring current intensity in the secondary cooling zone is controlled at 200-250A, and the secondary cooling water volume is 2.0L / kg-2.3L / kg; after the billet is removed from the line, it is stacked for slow cooling, with the stacking temperature not lower than 600℃ and the slow cooling time being more than 48 hours. 2) Billet Heating and Rolling: The billet is fed into a walking beam furnace for heating, passing through a preheating section, a heating section, and a soaking section before exiting the furnace. The preheating section temperature is 800–1150℃, the heating section temperature is 1280–1290℃, and the soaking section temperature is 1230–1260℃. The total furnace time for heating and soaking is 3–4 hours. The billet is rolled in two stages: the first stage is rough rolling, with an initial rolling temperature of 1150–1200℃, and no more than four passes. The reduction ratio for each pass is 20% or more for the first two passes, resulting in an intermediate billet thickness 3.5–4.5 times that of the finished product. The second stage is finish rolling, with an initial rolling temperature of 910–930℃. The reduction ratio for each pass in the finish rolling stage is 20% or more for the first two passes. 3) Cooling and straightening: An ultra-rapid cooling method is adopted, with an initial cooling temperature of 700–820℃, a cooling rate of 25–50℃ / s during the ultra-rapid cooling stage, and a final cooling temperature of 100–200℃. After the steel plate exits controlled cooling, side spraying and air purging are activated, with side spray pressure and water flow rate of 2–5MPa and 150–200m³, respectively. 3 At a pressure of 5-10 MPa, the air is blown at a rate of / h to straighten the product, followed by air cooling to room temperature.

2. The steel for saw blades according to claim 1, characterized in that, The steel used for the saw blade has a thickness of 6-20 mm and a width of 2200-3800 mm.

3. The steel for saw blades according to claim 1, characterized in that, The steel used for saw blades has a transverse tensile yield strength of 1250–1300 MPa, a tensile strength of 1400–1480 MPa, an elongation of ≥10%, a transverse Charpy impact energy of ≥35 J at 0℃, and a hardness of 50–60 HRC.

4. The steel for saw blades according to claim 1, characterized in that, In step 1), during the converter smelting process, the raw materials are pretreated with KR molten iron to control the S content to be below 0.015%, and then enter the converter after slag removal. During converter smelting, the P content is controlled to be ≤0.025%, and the C content is controlled to be 0.4-0.5% at the end of converter smelting. Then, LF refining is carried out, and argon gas is blown for 5-10 minutes when tapping the steel. During the LF refining process, Si-Ca wire is used for ladle refining treatment.

5. The steel for saw blades according to claim 1, characterized in that, In step 1), the superheat of continuous casting is 15-20℃, the casting speed is 0.8-1.1m / min, and the proportion of columnar crystals in the billet is controlled within 5%.

6. The steel for saw blades according to claim 1, characterized in that, The thickness of the cast billet is 150-170 mm.

7. The steel for saw blades according to claim 1, characterized in that, The fracture rate of the cast billet is controlled to be within 0.1%.

8. The steel for saw blades according to claim 1, characterized in that, In step 2), the billet is descaled for 1-2 minutes using high-pressure water at a pressure of 20-25 MPa, and then rolled; the billet is rolled into steel plate on a medium-thick plate reciprocating rolling mill.

9. The steel for saw blades according to claim 1, characterized in that, In step 3), the cooling medium for the ultra-fast cooling method is water; the straightening is a three-stage straightening process, with the inlet roller position at -1.0mm to -2.0mm and the outlet roller position at -2.6mm to -3.5mm.

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