A saw blade steel and a method of manufacturing the same

Abstract

This application relates to the field of medium and heavy plate manufacturing technology, and particularly to a saw blade steel and its preparation method. The method includes: first heating a steel billet with a predetermined chemical composition and controlling the initial temperature of the first heating of the steel billet; first rolling the first-heated steel billet and controlling the final rolling temperature of the first rolling to obtain a first intermediate billet; first cooling the first intermediate billet and then cutting it to obtain a first steel plate; second heating the first steel plate under a predetermined temperature; second rolling the second-heated first steel plate and controlling the final rolling temperature of the second rolling to obtain a second intermediate billet; and second cooling the second intermediate billet to bring it to a first target temperature for shearing to obtain saw blade steel. This application solves the technical problem that existing saw blade steels struggle to simultaneously achieve excellent mechanical properties and good surface quality.

Description

Technical Field

[0001] This application relates to the field of medium and heavy plate manufacturing technology, and in particular to a saw blade steel and its preparation method. Background Technology

[0002] Saw blade steel is widely used in ore cutting saw blades, timber cutting saw blades, and cold-cut metal circular saw blades. With the rapid development of China's manufacturing industry, the demand for saw blade steel is increasing year by year, and higher requirements are being placed on the performance of saw blade steel, requiring higher strength, hardness, and thermal stability to extend its service life.

[0003] To improve the strength and hardness of saw blade steel, the carbon content and carbon equivalent must be significantly increased, leading to increased stress and deformation resistance, and making it prone to problems such as billet breakage, poor plate shape, and cracks. Hot-rolled coil saw blade steel has a narrow width, and the steel plate has high stress and poor shape. Therefore, researching efficient and stable high-strength saw blade steel preparation methods for thick plates is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This application provides a saw blade steel and its preparation method to solve the technical problem that existing saw blade steels cannot simultaneously achieve excellent mechanical properties and good surface quality.

[0005] In a first aspect, this application provides a method for preparing saw blade steel, the method comprising:

[0006] A steel billet with a specified chemical composition is subjected to staged heating-rolling, wherein the staged heating-rolling includes:

[0007] First stage heating-rolling: The steel billet with a set chemical composition is first heated, and the initial temperature of the first heating of the steel billet is controlled;

[0008] The steel billet after the first heating is subjected to a first rolling process, and the final rolling temperature of the first rolling process is controlled to obtain a first intermediate billet;

[0009] The first intermediate billet is subjected to a first cooling process, followed by cutting to obtain the first steel plate;

[0010] Second stage heating-rolling: Under the condition of a set temperature, the first steel plate is heated a second time;

[0011] The first steel plate after the second heating is subjected to a second rolling process, and the final rolling temperature of the second rolling process is controlled to obtain a second intermediate billet;

[0012] The second intermediate billet is subjected to a second cooling process to bring it to a first target temperature for shearing to obtain saw blade steel.

[0013] Optionally, the initial heating temperature of the steel billet is ≥500℃.

[0014] Optionally, the temperature of the first heating is 1200-1220℃.

[0015] Optionally, the final rolling temperature of the first rolling process is 950-1050℃.

[0016] Optionally, the set temperature is 1250-1270℃.

[0017] Optionally, the final rolling temperature of the second rolling process is 830-880℃.

[0018] Optionally, the first target temperature is 100-200℃.

[0019] Optionally, the step of subjecting the first intermediate billet to a first cooling followed by cutting to obtain the first steel plate includes:

[0020] The first intermediate billet is subjected to a first cooling process, so that the second intermediate billet reaches a second target temperature for cutting to obtain a first steel plate; wherein the second target temperature is 150-200℃.

[0021] Optionally, the specified chemical composition includes:

[0022] C, Si, Mn, Ti, Cr, V, P, S, and Fe; where, by mass fraction,

[0023] The content of C is 0.70-0.85%, the content of Si is 0.20-0.40%, the content of Mn is 0.45-0.55%, the content of Ti is 0.020-0.030%, the content of Cr is 0.50-0.70%, the content of V is 0.15-0.25%, the content of P is <0.012%, and the content of S is <0.003%.

[0024] Secondly, this application provides a saw blade steel, which is prepared by the method described in any embodiment of the first aspect.

[0025] The technical solutions provided in this application have the following advantages compared with the prior art:

[0026] The saw blade steel preparation method provided in this application employs a high-C, high-Cr chemical composition design to ensure high strength and hardness of the steel plate; simultaneously, a significant amount of V is added, utilizing V precipitation and fine grain strengthening at high temperatures to enhance strength and hardness; trace amounts of Ti are added to inhibit austenite growth during heating; warm charging into the furnace and initial rolling avoid the risk of billet fracture, while obtaining thin intermediate billets, providing a good raw material guarantee for shape control in the second rolling; a second high-temperature heating and high-temperature rolling ensure the stability and good shape of the high-strength saw blade steel plate; a second cooling endpoint temperature is used to achieve a warm shearing process, avoiding cutting cracks. This method achieves stable production of high-strength saw blade steel plates, avoiding billet breakage, poor shape, and cracking problems, thus simultaneously achieving excellent mechanical properties and good surface quality. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic flowchart illustrating a method for preparing saw blade steel according to an embodiment of this application;

[0030] Figure 2 This refers to the second rolling process in a method for preparing saw blade steel provided in Embodiment 1 of this application;

[0031] Figure 3 This is the second rolling process in a method for preparing saw blade steel provided in Embodiment 2 of this application;

[0032] Figure 4 This is a microstructure diagram of a saw blade steel provided in Embodiment 1 of this application;

[0033] Figure 5 This is a microstructure diagram of a saw blade steel provided in Embodiment 2 of this application. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0036] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely 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. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0037] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0038] Firstly, this application provides a method for preparing saw blade steel; please refer to [link to relevant documentation]. Figure 1 The method described herein includes:

[0039] S0. A steel billet with a set chemical composition is subjected to staged heating-rolling, wherein the staged heating-rolling includes:

[0040] S1, First stage heating-rolling: The steel billet with a set chemical composition is first heated, and the initial temperature of the first heating of the steel billet is controlled;

[0041] The steel billet after the first heating is subjected to a first rolling process, and the final rolling temperature of the first rolling process is controlled to obtain a first intermediate billet;

[0042] The first intermediate billet is subjected to a first cooling process, followed by cutting to obtain the first steel plate;

[0043] In some embodiments, the specified chemical composition includes:

[0044] C, Si, Mn, Ti, Cr, V, P, S, and Fe; where, by mass fraction,

[0045] The content of C is 0.70-0.85%, the content of Si is 0.20-0.40%, the content of Mn is 0.45-0.55%, the content of Ti is 0.020-0.03%, the content of Cr is 0.50-0.7%, the content of V is 0.15-0.25%, the content of P is <0.012%, and the content of S is <0.003%.

[0046] In the embodiments of this application, the chemical composition design adopts a high C and high Cr chemical composition design to ensure that the steel plate has high strength and hardness; at the same time, more V is added to improve strength and hardness by utilizing the precipitation and fine grain strengthening of V at high temperature; and a trace amount of Ti is added to inhibit austenite growth during the heating process.

[0047] The positive effects of controlling the carbon content to 0.70-0.85% include ensuring high strength and hardness of the saw blade steel. If the carbon content is too high, it will lead to excessively high strength and hardness, reducing formability; if the carbon content is too low, it will reduce strength and hardness, shortening the service life of the saw blade steel. Specifically, the carbon content can be 0.70%, 0.80%, 0.85%, etc.

[0048] The positive effect of controlling the Si content to 0.20-0.40% is that it improves strength through solid solution strengthening. Specifically, the Si content can be 0.20%, 0.30%, 0.40%, etc.

[0049] The positive effects of controlling the Mn content to 0.45-0.55% include: improved strength and hardness through solid solution strengthening, while refining the microstructure. Specifically, the Mn content can be 0.45%, 0.50%, 0.55%, etc.

[0050] The positive effects of controlling the Ti content to 0.020-0.030% include: inhibiting abnormal austenite growth during high-temperature heating and refining the original austenite microstructure. If the Ti content is too high, it can lead to excessive Ti precipitation during rolling, affecting the steel plate's properties; if the Ti content is too low, it may not effectively inhibit austenite growth during heating. Specifically, the Ti content can be 0.020%, 0.025%, or 0.030%, etc.

[0051] The positive effects of controlling the Cr content to 0.50-0.70% include: improved hardenability, strength, and hardness of the steel plate through higher Cr content. However, excessively high Cr content can negatively impact the machinability of saw blade steel to some extent; conversely, excessively low Cr content can reduce the strength and hardness of the saw blade steel to some extent. Specifically, the Cr content can be 0.50%, 0.60%, 0.70%, etc.

[0052] The positive effects of controlling the V content to 0.15-0.25% include improved strength through V precipitation and grain refinement at high temperatures. If the V content is too high, it can lead to excessive precipitates, affecting the machining performance of the saw blade steel; if the V content is too low, it can reduce the performance of the saw blade steel to some extent. Specifically, the V content can be 0.15%, 0.20%, 0.25%, etc.

[0053] The positive effects of controlling the phosphorus (P) content to <0.012% include: controlling the content of harmful elements and improving the performance of saw blade steel. Specifically, the P content can be 0.011%, 0.010%, etc.

[0054] The positive effects of controlling the sulfur content to <0.003% include: controlling the content of harmful elements and improving the performance of saw blade steel. Specifically, the sulfur content can be 0.0029%, 0.0028%, etc.

[0055] In some embodiments, the initial heating temperature of the steel billet is ≥500°C.

[0056] Prior to the first stage of heating-rolling, the process includes:

[0057] Smelting: KR desulfurization and converter smelting are adopted, and top and bottom combined blowing is used; LF furnace and VD furnace are used for vacuum treatment to reduce the content of harmful gases such as O and H, as well as P and S.

[0058] Continuous casting: Design the billet shape for continuous casting, with a thickness of 300 mm and a width of 2000-2400 mm.

[0059] In this embodiment, the "first initial heating temperature of the billet" refers to the temperature at which the billet is charged into the furnace. Controlling the first initial heating temperature of the billet to ≥500℃ has the positive effect of avoiding the risk of billet breakage. If the temperature is too low, the large temperature difference between the billet and the furnace temperature after charging can easily cause the billet to break due to thermal stress. Specifically, the first initial heating temperature of the billet can be 500℃, 600℃, 700℃, etc.

[0060] In some embodiments, the temperature of the first heating is 1200-1220°C.

[0061] In this embodiment, the positive effects of controlling the first heating temperature to 1200-1220℃ are: high-temperature heating fully softens the steel billet, reducing its resistance to rolling deformation. Excessive heating temperature may lead to abnormal austenite growth, making the steel billet prone to fracture. Specifically, the first heating temperature can be 1200℃, 1210℃, 1200℃, etc. The first heating time is 300-500 minutes.

[0062] In some embodiments, the final rolling temperature of the first rolling is 950-1050°C.

[0063] In this embodiment, controlling the final rolling temperature of the first rolling process to 950-1050℃ has the following positive effects: ensuring that the rolling is carried out entirely within the recrystallization zone, resulting in sufficient homogenization and refinement of the microstructure. If the final rolling temperature of the first rolling process is too high, it may lead to insufficient microstructure refinement, affecting the final properties of the saw blade steel; if the final rolling temperature of the first rolling process is too low, it may cause poor sheet shape to some extent. Specifically, the final rolling temperature of the first rolling process can be 950℃, 1000℃, 1050℃, etc. The first rolling process also includes ensuring that at least two passes have a reduction rate ≥20%, ensuring sufficient recrystallization of the entire thickness section, achieving homogenization and refinement of the microstructure, and eliminating defects. The final thickness of the first intermediate billet is 130-150mm.

[0064] In some embodiments, the step of subjecting the first intermediate billet to a first cooling followed by cutting to obtain the first steel plate includes:

[0065] The first intermediate billet is subjected to a first cooling process, so that the second intermediate billet reaches a second target temperature for cutting to obtain a first steel plate; wherein the second target temperature is 150-200℃.

[0066] In this embodiment, the "first cooling" is slow cooling, where the intermediate billet is placed in a slow cooling pit and slowly cooled to the endpoint temperature of the slow cooling process, so as to cut it into the required intermediate billet size. The "second target temperature" represents the endpoint temperature of the first cooling, and also represents the initial cutting temperature of the intermediate billet. Controlling this temperature to 100-200°C has the positive effects of preventing blue brittleness from high-temperature cutting and cracking from low-temperature cutting. If the temperature is too low, it will make low-temperature cutting more prone to cracking. Specifically, the initial cutting temperature of the intermediate billet can be 150°C, 180°C, 200°C, etc.

[0067] S2, Second stage heating-rolling: Under the condition of a set temperature, the first steel plate is subjected to a second heating;

[0068] The first steel plate, after being heated a second time, undergoes a second rolling process, as shown in [reference needed]. Figure 2 The second rolling process in the method for preparing saw blade steel provided in Embodiment 1 of this application, and Figure 3 The second rolling process is provided in the saw blade steel preparation method of Embodiment 2 of this application; and the final rolling temperature of the second rolling is controlled to obtain a second intermediate billet;

[0069] The second intermediate billet is subjected to a second cooling process to bring it to a first target temperature for shearing to obtain saw blade steel.

[0070] In some embodiments, the set temperature is 1250-1270°C.

[0071] In this embodiment, after one rolling process, the microstructure of the intermediate billet has changed from a loose, as-cast structure to a dense, rolled structure, and the grains have been sufficiently refined, allowing it to withstand higher heating temperatures. "Set temperature" refers to the temperature of the second heating cycle. Controlling the second heating temperature to 1250-1270℃ has the following positive effects: ensuring the entire rolling process is carried out at a high temperature, guaranteeing good shape control of the saw blade steel. If the second heating temperature is too high, it may easily lead to deformation of the intermediate billet, affecting the rolling process; if the second heating temperature is too low, it may cause excessive temperature drop during the rolling process, making it impossible to guarantee the shape. Specifically, the second heating temperature can be 1250℃, 1260℃, 1270℃, etc. The second heating time is 130-300 minutes.

[0072] In some embodiments, the final rolling temperature of the second rolling is 830-880°C.

[0073] In this embodiment, controlling the final rolling temperature of the second rolling process to 830-880℃ has the following positive effects: ensuring good microstructure and shape control of the saw blade steel. If the final rolling temperature of the second rolling process is too high, it will to some extent lead to a coarse steel sheet microstructure, affecting performance; if the final rolling temperature of the second rolling process is too low, it will to some extent easily cause poor sheet shape. Specifically, the final rolling temperature of the second rolling process can be 830℃, 850℃, 880℃, etc.

[0074] In some implementations, the first target temperature is 100-200°C.

[0075] In this embodiment, "second cooling" is air cooling, and "first target temperature" represents the endpoint temperature of air cooling, which also represents the initial shearing temperature of the steel plate. Controlling this temperature to 100-200℃ has the positive effect of ensuring good cutting quality. If the temperature is too high, the steel plate may be prone to blue brittleness; if the temperature is too low, the steel plate may be prone to cracking. Specifically, the endpoint temperature of the second cooling can be 100℃, 150℃, 200℃, etc. The saw blade steel prepared by the method of the above embodiment has good microstructure uniformity, as can be seen in [reference needed]. Figure 4 A microstructure diagram of saw blade steel provided in Embodiment 1 of this application, and Figure 5 This is a microstructure diagram of a saw blade steel provided in Embodiment 2 of this application.

[0076] Secondly, this application provides a saw blade steel, which is prepared by the method described in any embodiment of the first aspect.

[0077] The saw blade steel is made based on the above-described saw blade steel preparation method. The specific steps of the saw blade steel preparation method can be referred to the above embodiments. Since the saw blade steel adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0078] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0079] This application provides a method for preparing saw blade steel, the method comprising:

[0080] S0. A steel billet with a set chemical composition is subjected to staged heating-rolling, wherein the staged heating-rolling includes:

[0081] S1, First stage heating-rolling: The steel billet with a set chemical composition is first heated, and the initial temperature of the first heating of the steel billet is controlled;

[0082] The steel billet after the first heating is subjected to a first rolling process, and the final rolling temperature of the first rolling process is controlled to obtain a first intermediate billet;

[0083] The first intermediate billet is subjected to a first cooling process, followed by cutting to obtain the first steel plate;

[0084] S2, Second stage heating-rolling: Under the condition of a set temperature, the first steel plate is subjected to a second heating;

[0085] The first steel plate after the second heating is subjected to a second rolling process, and the final rolling temperature of the second rolling process is controlled to obtain a second intermediate billet;

[0086] The second intermediate billet undergoes a second cooling process to bring it to a first target temperature for shearing, yielding saw blade steel. Specific process parameters are shown in Tables 1 and 2.

[0087] Table 1 shows the chemical composition (wt%) of the saw blade steel, with the remainder being Fe and unavoidable impurities.

[0088] Serial Number C Si Mn Ti Cr V P S Example 1 0.79 0.29 0.56 0.027 0.53 0.20 0.01 0.0014 Example 2 0.81 0.32 0.51 0.022 0.52 0.17 0.008 0.0005 Example 3 0.85 0.35 0.52 0.026 0.65 0.21 0.007 0.0004 Example 4 0.70 0.25 0.51 0.022 0.55 0.23 0.009 0.0007 Comparative Example 1 0.85 0.36 0.47 0.027 0.62 0.22 0.008 0.0006 Comparative Example 2 0.85 0.28 0.55 0.025 0.61 0.23 0.009 0.0008 Comparative Example 3 0.06 0.38 0.50 - 0.61 0.18 0.010 0.002

[0089] Table 2. Process parameters for preparing saw blade steel

[0090]

[0091] The saw blade steels prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to mechanical property and external quality tests. The test results are shown in Table 3.

[0092] Table 3. Test results of mechanical properties and external quality of saw blade steel

[0093]

[0094]

[0095] In Examples 1-4, efficient and stable production of high-strength saw blade steel plates was achieved, meeting the requirements of high strength and high hardness, while maintaining good plate shape and eliminating cutting cracks. In Comparative Example 1, a single heating and rolling process was used, resulting in poor plate flatness; in Comparative Example 2, a non-heated shearing process was used, leading to cutting cracks; in Comparative Example 3, a Ti-free system was used, and the C content was lower than that of this application, resulting in poor strength and hardness properties; all of these are outside the scope of the embodiments in this application.

[0096] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing saw blade steel, characterized in that, The method includes: A steel billet with a specified chemical composition is subjected to staged heating-rolling, wherein the staged heating-rolling includes: First stage heating-rolling: The steel billet with a set chemical composition is first heated, and the initial temperature of the first heating of the steel billet is controlled to be ≥500℃, and the temperature of the first heating is 1200-1220℃; The steel billet after the first heating is subjected to a first rolling process, and the final rolling temperature of the first rolling process is controlled at 950-1050℃, so as to complete the microstructure refinement and homogenization in the fully recrystallized zone and obtain a first intermediate billet. The first intermediate billet is subjected to a first cooling process to bring it to a second target temperature of 150-200°C, so that it can be cut to obtain a first steel plate. Second stage heating-rolling: The first steel plate is heated a second time at a set temperature of 1250-1270℃; The first steel plate, after being heated a second time, is subjected to a second rolling process, and the final rolling temperature of the second rolling process is controlled to be... The second intermediate billet is obtained at 830-880℃. The second intermediate billet is subjected to a second cooling process to bring it to a first target temperature of 100-200°C for shearing to obtain saw blade steel. The specified chemical components include: C, Si, Mn, Ti, Cr, V, P, S, and Fe; where, by mass fraction, The C content is 0.70-0.85%, the Si content is 0.20-0.40%, the Mn content is 0.45-0.55%, and the Ti content is... The content of Cr is 0.020-0.030%, the content of V is 0.50-0.70%, the content of P is <0.012%, and the content of S is <0.003%.

2. A saw blade steel, characterized in that, The saw blade steel is prepared by the method described in claim 1.

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