High-temperature-resistant pressing plate for slab continuous casting flame cutting machine and preparation method of high-temperature-resistant pressing plate

Abstract

The invention relates to a high-temperature-resistant pressing plate for a slab continuous casting flame cutting machine and a preparation method, and belongs to the technical field of special alloy materials and continuous casting equipment. The high-temperature-resistant pressing plate comprises the following chemical components in percentage by mass: 0.03%-0.04% of C, less than or equal to 0.75% of Si, less than or equal to 2.0% of Mn, less than or equal to 0.045% of P, less than or equal to 0.03% of S, 16.5%-17.5% of Cr, 12.5%-13.5% of Ni, 2.8%-3.2% of Mo, 0.4%-0.6% of Ti, 0.003%-0.005% of B and the balance of Fe and inevitable impurities. Wherein the mass fraction ratio of Ti to C is 8-10. Through the synergistic effect of component optimization, phase structure regulation and control and the preparation process of the high-temperature-resistant pressing plate, the high-temperature performance and stability of the high-temperature-resistant pressing plate are remarkably improved, the service life of the high-temperature-resistant pressing plate is remarkably prolonged, and therefore the technical problems of high-temperature softening deformation, insufficient material service life and the like of a traditional pressing plate are solved.

Description

Technical Field

[0001] The present application relates to the technical field of special alloy materials and continuous casting equipment, and in particular to a high-temperature resistant pressing plate for a slab continuous casting flame cutting machine and a preparation method thereof. Background Art

[0002] As a key piece of equipment in a continuous casting production line, the performance of a slab flame cutting machine directly impacts the cutting accuracy and overall production efficiency of the slab. The pressure plate, a metal component mounted on the flame cutting machine's pressure head, is primarily used to clamp the slab under high-temperature conditions of 800±50°C and prevent the cutting machine from slipping. Its core design requirements include high-temperature strength retention, resistance to thermal deformation, and wear resistance. However, existing pressure plates exhibit a number of issues under high-temperature conditions, severely hindering the stable operation of the cutting machine and cutting quality.

[0003] Traditionally, 42CrMo alloy steel has been widely used in the manufacture of pressure plates. This material has high strength at room temperature, meeting certain requirements. However, when the operating temperature reaches around 800°C, the microstructure of 42CrMo alloy steel undergoes a pearlite-austenite phase transformation, causing its hardness to drop sharply from HRC28 to HRC12. Its yield strength also decreases to only 90 MPa, a mere 9.7% of its room temperature value. This high-temperature softening phenomenon makes the pressure plate susceptible to deformation during the cutting process, reducing clamping stability, causing the cutting machine to slip, resulting in uneven incisions on the ingot, and a crescent-shaped scrap rate as high as 4.7% to 5.8%. This not only affects product quality but also increases production costs and maintenance difficulties.

[0004] To overcome the high-temperature performance shortcomings of 42CrMo alloy steel, the industry has attempted to use conventional austenitic stainless steels (such as 316 stainless steel) as alternatives. While 316 stainless steel offers superior high-temperature stability to 42CrMo, its insufficient Mo content (2.0% to 2.5%) results in a high-temperature strength of only 135 MPa, still insufficient for use in extreme high-temperature conditions. Furthermore, the Cr23C6 carbides in 316 stainless steel aggregate at 800°C and induce intergranular corrosion, further reducing the material's durability. On the other hand, while 310S stainless steel offers high high-temperature strength, its excessively high Ni content (19% to 22%) results in a 400% surge in material costs. Furthermore, it still suffers from σ-phase embrittlement, resulting in an impact energy of less than 30 J, limiting its widespread industrial application. Beyond the inherent material issues, existing press plates face other challenges. For example, the friction coefficient of the working surface of conventional press plates fluctuates significantly, increasing the risk of slippage and impacting cutting accuracy and stability. In addition, oxidation and deformation of the pressure plate at high temperatures also shorten its lifespan, requiring frequent replacement, increasing maintenance costs and production downtime. Summary of the Invention

[0005] The present application provides a high-temperature resistant pressing plate for a slab continuous casting flame cutting machine and a preparation method thereof, in order to solve the following technical problem: how to improve the high-temperature performance of the pressing plate.

[0006] In the first aspect, an embodiment of the present application provides a high-temperature resistant pressing plate for a slab continuous casting flame cutting machine. The chemical composition of the high-temperature resistant pressing plate, measured by mass fraction, is: C: 0.03% to 0.04%, Si≤0.75%, Mn≤2.0%, P≤0.045%, S≤0.03%, Cr: 16.5% to 17.5%, Ni: 12.5% ​​to 13.5%, Mo: 2.8% to 3.2%, Ti: 0.4% to 0.6%, B: 0.003% to 0.005%, and the remainder is Fe and unavoidable impurities; wherein the mass fraction ratio of Ti to C is 8 to 10.

[0007] Optionally, in the microstructure of the high temperature resistant pressed plate, the volume fraction of delta ferrite is less than 3%.

[0008] Optionally, the microstructure further includes a TiC phase with a volume fraction of 3% to 5%, and the particle size of the TiC phase is 50 nm to 80 nm.

[0009] Optionally, at 800° C., the high temperature resistant press plate meets at least one of the following properties: a yield strength of 200 MPa to 220 MPa, and a thermal deformation of 0.1 mm to 0.12 mm in 100 hours.

[0010] Optionally, the high temperature resistant pressing plate is suitable for a slab continuous casting and cutting process with a drawing speed of 1.7 m / min to 2.2 m / min.

[0011] In a second aspect, the present application provides a method for preparing the high temperature resistant press plate described in the first aspect, the method comprising:

[0012] obtaining a steel ingot having the chemical composition;

[0013] The steel ingot is sequentially heated, multi-directionally forged and solution treated to obtain a semi-finished high-temperature resistant press plate;

[0014] The surface of the semi-finished high-temperature resistant pressed plate is strengthened to obtain a finished high-temperature resistant pressed plate.

[0015] Optionally, the heating temperature is 1100° C. to 1150° C., and the heating insulation time is 120 min to 135 min.

[0016] Optionally, the deformation amount of the multi-directional forging is ≥60%, and the final forging temperature of the multi-directional forging is ≥900°C.

[0017] Optionally, the temperature of the solution treatment is 1080° C. to 1100° C., and the water quenching time of the solution treatment is 90 min to 105 min.

[0018] Optionally, the surface strengthening of the semi-finished high-temperature resistant pressed plate to obtain a finished high-temperature resistant pressed plate comprises:

[0019] The working area of ​​the semi-finished high-temperature resistant press plate is subjected to laser cladding WC-10Co coating treatment, and the non-working area of ​​the semi-finished high-temperature resistant press plate is subjected to shot peening treatment to obtain a finished high-temperature resistant press plate.

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

[0021] The present invention provides a high-temperature resistant press plate for a slab continuous casting flame cutting machine. The chemical composition of the press plate, measured by mass, is as follows: C: 0.03% to 0.04%, Si ≤ 0.75%, Mn ≤ 2.0%, P ≤ 0.045%, S ≤ 0.03%, Cr: 16.5% to 17.5%, Ni: 12.5% ​​to 13.5%, Mo: 2.8% to 3.2%, Ti: 0.4% to 0.6%, B: 0.003% to 0.005%, with the remainder being Fe and unavoidable impurities. The mass ratio of Ti to C is 8 to 10. The addition of Mo and a trace amount of B achieves solid solution strengthening and grain boundary strengthening. Mo improves the material's high-temperature strength, while B helps reduce defects at grain boundaries and improves the material's creep resistance. The addition of Ti and strict control of the Ti to C mass ratio form a nanoscale TiC phase. This nano-scale TiC phase can effectively hinder dislocation movement and enhance the material's bearing capacity, allowing the press plate to maintain a high yield strength and hardness at high temperatures, effectively solving the problem of high-temperature softening and deformation, and significantly improving the high-temperature performance, stability and life of the press plate. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 A schematic flow chart of a method for preparing a high-temperature resistant pressing plate for a slab continuous casting flame cutting machine provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] The range descriptions described in this article, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values ​​within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including", "comprising", etc. used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or at the same time; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the article, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0027] In the first aspect, an embodiment of the present application provides a high-temperature resistant pressing plate for a slab continuous casting flame cutting machine. The chemical composition of the high-temperature resistant pressing plate, measured by mass fraction, is: C: 0.03% to 0.04%, Si≤0.75%, Mn≤2.0%, P≤0.045%, S≤0.03%, Cr: 16.5% to 17.5%, Ni: 12.5% ​​to 13.5%, Mo: 2.8% to 3.2%, Ti: 0.4% to 0.6%, B: 0.003% to 0.005%, and the remainder is Fe and unavoidable impurities; wherein the mass fraction ratio of Ti to C is 8 to 10.

[0028] The positive effect of limiting the mass fraction of C to 0.03% to 0.04%: By limiting the mass fraction of C to 0.03% to 0.04%, the precipitation of carbides can be significantly reduced. In the embodiment of the present application, a mass fraction of C higher than 0.04% will lead to the formation of carbides, which may aggregate and induce intergranular corrosion at high temperatures, thereby reducing the performance of the material. Therefore, limiting the mass fraction of C to 0.03% to 0.04% helps maintain the stability of the material and extend its service life. For example, the mass fraction of C can be 0.03%, 0.032%, 0.034%, 0.036%, 0.038%, 0.04%, etc.

[0029] The positive effect of limiting Si to ≤ 0.75% is that a silicon mass fraction exceeding 0.75% may promote the formation of σ phase (Fe-Cr-Mo-Si intermetallic compound), especially accelerating grain boundary embrittlement at high temperatures (e.g., 800°C). For example, the Si mass fraction may be 0.15%, 0.25%, 0.35%, 0.45%, 0.55%, 0.65%, 0.75%, etc.

[0030] The positive effects of limiting Mn to ≤ 2.0%: Manganese is an austenite-stabilizing element. A mass fraction exceeding 2.0% can exacerbate the stability of the austenite structure at high temperatures, leading to decreased phase transformation resistance and embrittlement issues such as σ phase precipitation. By limiting Mn to ≤ 2.0%, excessive austenite stabilization can be avoided, thereby suppressing grain boundary sliding and σ phase embrittlement at high temperatures and ensuring the toughness of the material. For example, the mass fraction of Mn can be 0.4%, 0.8%, 1.2%, 1.6%, 2.0%, etc.

[0031] The positive effect of limiting P to ≤ 0.045% is that phosphorus tends to segregate at grain boundaries at high temperatures, forming low-melting-point compounds (such as Fe-P eutectic phase), which leads to grain boundary weakening and increased risk of brittle fracture. By controlling the mass fraction of P to below 0.045%, this type of grain boundary embrittlement can be significantly reduced, ensuring the material's impact resistance at 800°C. For example, the mass fraction of P can be 0.005%, 0.010%, 0.015%, 0.020%, 0.025%, 0.030%, 0.035%, 0.040%, 0.045%, etc.

[0032] The positive effect of limiting S ≤ 0.03%: Sulfur easily combines with manganese in steel to form MnS inclusions. When the mass fraction of S is higher than 0.03%, these inclusions will preferentially precipitate along the grain boundaries at high temperatures (such as 800°C), resulting in decreased material toughness and weakening of the grain boundaries. Limiting S ≤ 0.03% can reduce the formation of brittle phases and avoid intergranular fracture of the press plate during high-temperature clamping. For example, the mass fraction of S can be 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, etc.

[0033] The positive effect of limiting the Cr mass fraction to 16.5% to 17.5% is that Cr is a core alloying element in austenitic stainless steel. A mass fraction of 16.5% to 17.5% can form a dense Cr2O3 oxide film at high temperatures (800°C), significantly inhibiting the substrate oxidation rate. For example, the Cr mass fraction can be 16.5%, 16.7%, 16.9%, 17.1%, 17.3%, 17.5%, etc.

[0034] The positive effect of limiting the Ni mass fraction to 12.5% ​​to 13.5% is that it effectively stabilizes the austenite matrix. At 800°C, Ni can inhibit the formation of delta ferrite, preventing the risk of high-temperature embrittlement. For example, the Ni mass fraction can be 12.5%, 12.7%, 12.9%, 13.1%, 13.3%, 13.5%, and so on.

[0035] The positive effects of limiting the Mo mass fraction to 2.8% to 3.2% are as follows: Mo is a key alloying element in stainless steel. Its solid solution in the matrix significantly improves the material's strength and hardness. By controlling the Mo mass fraction within the range of 2.8% to 3.2%, its solid solution strengthening effect is maximized, allowing the platen assembly to maintain high yield strength and hardness at high temperatures, thus meeting the high-temperature performance requirements of slab flame cutting machines. For example, the Mo mass fraction can be 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, etc.

[0036] The positive effect of limiting the mass fraction of Ti to 0.4% to 0.6%: When Ti is added within the mass fraction range of 0.4% to 0.6%, it can combine with the C element in steel to form a nano-scale TiC phase, replacing the Cr in traditional materials. 23Precipitation of C6 carbide. This nano-TiC phase has higher thermal stability at high temperatures and can effectively inhibit intergranular corrosion and σ phase embrittlement problems. A Ti mass fraction exceeding 0.6% will lead to a surge in material costs (titanium is a precious metal element), while a Ti mass fraction below 0.4% will not be able to fully form a strengthening phase. A Ti mass fraction of 0.4% to 0.6% can not only meet high-temperature performance requirements, but also reduce costs by 60% compared to the 310S stainless steel solution. For example, the mass fraction of Ti is 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, and the like.

[0037] The positive effect of limiting the mass fraction of B to 0.003% to 0.005% is that the B element can effectively pin grain boundary slip and inhibit high-temperature creep by segregating at austenite grain boundaries. In addition, the binding energy between B and Cr is relatively high (about 2.1 eV), which can preferentially form a B-Cr composite phase and reduce the segregation of Cr at grain boundaries. For example, the mass fraction of B can be 0.003%, 0.0035%, 0.004%, 0.0045%, 0.005%, etc.

[0038] The positive effect of the mass fraction ratio of Ti and C being 8 to 10: by controlling the Ti / C ratio within the range of 8 to 10, the stoichiometric ratio of titanium to carbon is balanced, which not only avoids the chromium depletion phenomenon at the grain boundaries caused by free carbon, but also suppresses the grain boundary sliding and creep rates at high temperatures.

[0039] In some embodiments, the volume fraction of delta ferrite in the microstructure of the high temperature resistant pressed plate is less than 3%.

[0040] Ferrite is one of the allotropes of iron and is usually divided into α-ferrite and δ-ferrite. α-ferrite exists at lower temperatures, while δ-ferrite (Delta Ferrite) is a ferrite phase formed at high temperatures in steel materials and has a body-centered cubic (BCC) crystal structure. During the solidification or high-temperature heat treatment of steel, when the temperature is higher than 1394°C, δ-ferrite will precipitate directly from the liquid steel or form in the austenite region. Excessive δ-ferrite may affect the mechanical properties and processability of the material. δ-ferrite has poor stability at high temperatures and can easily lead to a decrease in material strength or deformation. Therefore, controlling the δ-ferrite content helps improve the material's high-temperature strength and deformation resistance. In addition, the high-temperature resistant press plate also contains TiC phase. As a strengthening phase, TiC may improve material properties through a dispersion strengthening mechanism. However, if there is too much δ-ferrite, it may interfere with the distribution of TiC or reduce the overall strength of the matrix, so it needs to be strictly controlled. For example, in the microstructure of the high temperature resistant pressed plate, the volume fraction of delta ferrite may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc.

[0041] The multi-directional forging and solution treatment in the preparation method of this application may help refine the grain size and reduce the formation of delta ferrite. For example, the solution treatment of high temperature heating and rapid cooling can inhibit the precipitation of delta ferrite and maintain the stability of the austenite matrix.

[0042] In some embodiments, the microstructure further includes a TiC phase with a volume fraction of 3% to 5%, and the particle size of the TiC phase is 50 nm to 80 nm.

[0043] TiC, a ceramic phase with extremely high hardness and strength, is uniformly distributed within the stainless steel matrix at a volume fraction of 3% to 5% and a particle size of 50nm to 80nm. This phase significantly improves the high-temperature strength of the pressure plate assembly. These nano-sized TiC particles effectively hinder dislocation motion, enhancing the material's load-bearing capacity and enabling the pressure plate assembly to maintain high yield strength and hardness even at high temperatures. TiC possesses excellent wear resistance. During the slab flame cutting process, the pressure plate assembly is subject to mechanical forces such as cutting forces and friction, which can easily cause wear. The presence of nano-TiC significantly improves the material's wear resistance, reduces wear on the pressure plate assembly, and extends its service life. The uniform distribution of nano-TiC within the stainless steel matrix also refines the matrix structure. The fine TiC particles act as heterogeneous nucleation sites, promoting refinement of the stainless steel matrix structure and ultimately improving the material's strength, hardness, and toughness. For example, in the microstructure, the volume fraction of the TiC phase can be 3%, 3.5%, 4%, 4.5%, 5%, etc.; the particle size of the TiC phase can be 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, etc.

[0044] In some embodiments, at 800° C., the high temperature resistant press plate meets at least one of the following properties: a yield strength of 200 MPa to 220 MPa, and a thermal deformation of 0.1 mm to 0.12 mm after 100 hours.

[0045] Under high temperature environment of 800℃, many traditional materials will soften and their yield strength will drop significantly, resulting in the inability of the pressure plate to stably clamp the ingot. However, the high temperature resistant pressure plate of the embodiment of the present application can still maintain a yield strength of 200MPa to 220MPa at 800℃, effectively resisting high temperature softening and deformation, and ensuring the stability of the cutting process. The reduction in the yield strength of materials at high temperatures is one of the main reasons for cutting slippage. The high temperature resistant pressure plate of the embodiment of the present application can still maintain a high yield strength at 800℃, can firmly clamp the ingot, and prevent cutting slippage caused by material softening, thereby ensuring cutting accuracy and cut quality. Cutting slippage often leads to uneven incisions of the ingot and produces crescent-shaped scrap. The high temperature resistant pressure plate of the embodiment of the present application significantly reduces the crescent-shaped scrap rate by maintaining high yield strength at high temperatures, thereby improving cutting efficiency and finished product quality. In high-temperature environments, a material's yield strength is one of the key factors affecting its service life. The high-temperature resistant press plate of the present embodiment maintains a high yield strength at 800°C, meaning it can operate stably and for extended periods at high temperatures. This extends the press plate's service life and reduces replacement frequency and maintenance costs. For example, at 800°C, the yield strength of the high-temperature resistant press plate can be 200 MPa, 204 MPa, 208 MPa, 212 MPa, 216 MPa, 220 MPa, and so on.

[0046] "100h thermal deformation" refers to the plastic deformation of the high temperature resistant pressing plate after being continuously heated for 100 hours (about 4.17 days) under a specific temperature and constant stress. This parameter is the core indicator for measuring the high temperature creep resistance of the material. The smaller the value, the better the high temperature stability of the material. In the embodiment of the present application, under a high temperature condition of 800°C (corresponding to the working temperature of the slab continuous casting flame cutting machine), the high temperature resistant pressing plate is continuously loaded for 100 hours, and the plastic deformation generated is 0.1mm~0.12mm, and the high temperature stability performance is excellent. For example, at 800°C, the 100h thermal deformation of the high temperature resistant pressing plate can be 0.1mm, 0.105mm, 0.11mm, 0.115mm, 0.12mm, etc.

[0047] In some embodiments, the high temperature resistant pressing plate is suitable for a slab continuous casting and cutting process with a drawing speed of 1.7 m / min to 2.2 m / min.

[0048] A casting speed of 1.7 to 2.2 m / min ensures efficient operation of the continuous casting line, placing higher demands on the stability and durability of the pressure plate assembly. At a casting speed of 1.7 to 2.2 m / min, the pressure plate assembly must withstand greater mechanical and thermal stresses. The high-temperature-resistant pressure plate of the present embodiment exhibits excellent high-temperature performance and deformation resistance, making it suitable for slab continuous casting and cutting processes at casting speeds of 1.7 to 2.2 m / min.

[0049] Figure 1 A schematic flow chart of a method for preparing a high-temperature resistant pressing plate for a slab continuous casting flame cutting machine provided in an embodiment of the present application.

[0050] See Figure 1 In a second aspect, the present application provides a method for preparing the high temperature resistant press plate described in the first aspect, the method comprising:

[0051] S1, obtaining a steel ingot having the chemical composition;

[0052] This application can use vacuum induction melting (VIM) + electroslag remelting (ESR) duplex process for smelting, and then cast to obtain steel ingots. The vacuum induction melting (VIM) + electroslag remelting (ESR) duplex process is a composite refining technology for preparing high-performance alloy materials. Its core purpose is to significantly improve the purity, uniformity and high-temperature performance of the material through multi-stage purification and tissue optimization. Vacuum induction melting (VIM) is to melt metal by electromagnetic induction heating under a vacuum environment, effectively remove gas and impurities, and improve material purity. Electroslag remelting (ESR) uses pre-melted steel ingots as electrodes, and melts them in conductive slag (such as CaF2-based slag system) through electricity. The liquid metal solidifies dropwise through the slag layer to achieve secondary refining. The duplex process combines the advantages of both, first preliminarily purified by VIM, and then deeply refined by ESR, so as to obtain higher quality alloy materials.

[0053] S2, sequentially heating, multi-directional forging and solution treating the steel ingot to obtain a semi-finished high-temperature resistant press plate;

[0054] In some embodiments, the heating temperature is 1100° C. to 1150° C., and the heating holding time is 120 min to 135 min.

[0055] Heating to 1100°C to 1150°C and holding for 120 to 135 minutes ensures uniform temperature distribution within the material, allowing alloying elements in the structure to fully diffuse and achieve a homogenized structure. This helps eliminate component segregation and casting defects in the material and improves its overall performance. Heating and holding within the 1100°C to 1150°C temperature range allows the material to undergo proper recovery and recrystallization, thereby improving its plasticity. This is very beneficial for subsequent forging, rolling, and other processing processes, reducing processing difficulty and improving the material's formability. Heating to 1100°C to 1150°C and holding can reduce the material's resistance to deformation, meaning that under the same processing conditions, less force needs to be applied, thereby reducing equipment wear and energy consumption and improving processing efficiency.

[0056] In some embodiments, the deformation amount of the multi-directional forging is ≥ 60%, and the finish forging temperature of the multi-directional forging is ≥ 900°C.

[0057] Multi-directional forging is a plastic processing technology that changes the shape and internal structure of metal materials by applying pressure in different directions. The core of this technology is to optimize the material structure through multi-dimensional deformation.

[0058] Multi-directional forging can break up the original as-cast structure, eliminate internal defects such as pores and loose, and make the structure more dense and uniform by subjecting the material to uniform forging in various directions. A deformation amount ≥ 60% can ensure that the material undergoes sufficient plastic deformation, so that the original coarse grains are refined to form a fine-grained structure. This fine-grained structure not only improves the strength of the material, but also enhances its toughness and plasticity. After multi-directional forging, the distribution of alloying elements in the material is more uniform, avoiding performance unevenness caused by element segregation. A deformation amount ≥ 60% increases the dislocation density in the material, producing more substructures and strengthening phases, thereby significantly improving the high-temperature strength and creep resistance of the material.

[0059] TiC phase is an important strengthening phase that plays an important role in improving the high-temperature strength and wear resistance of the material. However, at high temperatures, TiC phase is prone to coarsening, which weakens the strengthening effect. By setting the finish forging temperature at ≥ 900°C, it can be ensured that the TiC phase maintains a small particle size during forging, avoiding coarsening and thus maintaining the excellent performance of the material. In addition, a finish forging temperature ≥ 900°C is beneficial to maintaining sufficient dynamic recrystallization ability of the material during plastic deformation, refining austenite grains, and improving material density and uniformity.

[0060] Solution treatment is a heat treatment process that makes alloying elements fully dissolve in the matrix metal by high-temperature heating, and forms a supersaturated solid solution by rapid cooling. In the embodiments of the present application, this process is used to optimize the high-temperature performance of the pressure plate.

[0061] In some embodiments, the temperature of the solution treatment is 1080°C to 1100°C, and the water quenching time of the solution treatment is 90 min to 105 min.

[0062] Through solution treatment at 1080℃~1100℃, alloying elements (especially Cr, Ni, Mo, etc.) can be fully dissolved, eliminating the possible component segregation during the forging process and forming a uniform austenite matrix. At the same time, this temperature range can not only avoid the excessive formation of delta ferrite (control the volume fraction to <3%), but also prevent the degradation of mechanical properties caused by grain coarsening. The setting of water quenching time of 90min~105min ensures sufficient cooling time to fully stabilize the austenite structure, while avoiding the structural stress and cracks caused by excessive cooling. After optimized solution treatment, the TiC phase and other strengthening phases in the high-temperature resistant pressure plate are effectively formed and distributed, significantly improving the yield strength and deformation resistance of the material at high temperatures. This is particularly important for the pressure plate assembly of the slab flame cutting machine because it needs to maintain a stable clamping force in a high-temperature environment to avoid cutting slippage and the formation of crescent-shaped incisions.

[0063] S3. Strengthening the surface of the semi-finished high-temperature resistant pressed plate to obtain a finished high-temperature resistant pressed plate.

[0064] In some embodiments, the surface strengthening of the semi-finished high temperature resistant pressed plate to obtain a finished high temperature resistant pressed plate comprises:

[0065] The working area of ​​the semi-finished high-temperature resistant press plate is subjected to laser cladding WC-10Co coating treatment, and the non-working area of ​​the semi-finished high-temperature resistant press plate is subjected to shot peening treatment to obtain a finished high-temperature resistant press plate.

[0066] Laser cladding of WC-10Co coating is a surface strengthening technology that uses a high-energy laser beam to melt a tungsten carbide (WC) and cobalt (Co) alloy powder onto a metal substrate, forming a composite coating with high hardness, wear resistance, and high-temperature stability. In this embodiment, this technology is applied to the working area of ​​the pressure plate, with a coating thickness of 0.3mm to 0.4mm to improve its wear resistance under high-temperature conditions.

[0067] Shot peening is a surface strengthening process that forms a compressive stress layer by impacting the material surface with high-speed projectiles, thereby enhancing the fatigue strength and stress corrosion resistance of the material. In the embodiment of this application, shot peening is applied to the non-working area of ​​the pressure plate. By controlling the surface roughness (Ra≤0.8μm), the dual technical effects of dimensional stability and fatigue resistance can be achieved. Shot peening forms a synergistic effect with laser cladding WC-10Co coating treatment, and the overall performance is optimized through partitioning treatment.

[0068] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0069] Example 1

[0070] Calculated by mass fraction, the chemical composition of the steel ingot is: C: 0.04%, Si≤0.45%, Mn≤1.8%, P≤0.025%, S≤0.009%, Cr: 16.5%, Ni: 13.5%, Mo: 2.9%, Ti: 0.4%, B: 0.0037%, and the balance is Fe and unavoidable impurities.

[0071] The steel ingot was heated to 1150°C and kept at this temperature for 2 hours, and multi-directional forging was performed (deformation 70%), with the final forging temperature at 910°C.

[0072] Solution treatment: heat the forging billet to 1080℃ and water quench for 100 minutes.

[0073] Surface strengthening: The working surface is laser clad with WC-10Co coating (thickness 0.4 mm), and the non-working area is shot peened (Ra is 0.6 μm).

[0074] Example 2

[0075] Calculated by mass fraction, the chemical composition of the steel ingot is: C: 0.04%, Si≤0.27%, Mn≤0.6%, P≤0.019%, S≤0.021%, Cr: 17.5%, Ni: 12.5%, Mo: 2.9%, Ti: 0.4%, B: 0.0042%, and the balance is Fe and unavoidable impurities.

[0076] The steel ingot was heated to 1150°C and kept at this temperature for 2 hours, and multi-directional forging was performed (deformation amount 65%), and the final forging temperature was 900°C.

[0077] Solution treatment: heat the forging billet to 1090℃ and water quench for 95 minutes.

[0078] Surface strengthening: The working surface is laser clad with WC-10Co coating (thickness 0.3mm), and the non-working area is shot peened (Ra is 0.6μm).

[0079] Example 3

[0080] Calculated by mass fraction, the chemical composition of the steel ingot is: C: 0.04%, Si≤0.53%, Mn≤1.2%, P≤0.017%, S≤0.011%, Cr: 16.8%, Ni: 12.7%, Mo: 3.1%, Ti: 0.4%, B: 0.0044%, and the balance is Fe and unavoidable impurities.

[0081] The steel ingot was heated to 1150°C and kept at this temperature for 2 hours, and multi-directional forging was performed (deformation 80%), with the final forging temperature at 920°C.

[0082] Solution treatment: heat the forging billet to 1100℃ and water quench for 1.5h.

[0083] Surface strengthening: The working surface is laser clad with WC-10Co coating (thickness 0.3mm), and the non-working area is shot peened (Ra is 0.6μm).

[0084] Comparative Example 1

[0085] This example uses conventional 316 stainless steel.

[0086] Comparative Example 2

[0087] This example is a 42CrMo press plate.

[0088] The above examples and comparative examples were subjected to performance tests, and the obtained data are shown in Table 2.

[0089] Table 2

[0090] Group 800℃ yield strength 800℃ thermal deformation (100h) Annual replacement times Example 1 220MPa 0.12mm 2 times Example 2 215MPa 0.11mm 2 times Example 3 220MPa 0.1mm 2 times Comparative Example 1 135MPa 0.8mm 8 times Comparative Example 2 90MPa 2.1mm 26 times

[0091] It can be seen from the examples and comparative examples that the high-temperature resistant press plate provided in the examples of the present application has a maximum yield strength of 220 MPa at a high temperature of 800°C, which is significantly improved compared to the 90 MPa of the traditional 42CrMo press plate and the 135 MPa of conventional 316 stainless steel. It effectively solves the problem of high-temperature softening and deformation. The high-temperature resistant press plate provided in the examples of the present application has effectively controlled the amount of thermal deformation at high temperatures, and the deformation within 100 hours is only 0.1 mm to 0.12 mm, which is much lower than the 2.1 mm of the traditional 42CrMo press plate and the 0.8 mm of conventional 316 stainless steel, thereby ensuring cutting accuracy and stability. The service life of the high-temperature resistant press plate provided in the examples of the present application is also extended, greatly reducing maintenance costs and replacement frequency.

[0092] One or more technical solutions in the embodiments of the present invention may have at least the following technical effects or advantages:

[0093] Since the high temperature resistant pressing plate provided by the embodiment of the present invention has stable high temperature performance and good clamping stability, it effectively avoids the problems of cutting vehicle slipping and uneven incision of the ingot (crescent-shaped waste), and significantly improves the cutting quality and product qualification rate.

[0094] The foregoing is merely a detailed description of the present invention, intended to enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A high-temperature resistant pressing plate for a slab continuous casting flame cutting machine, wherein the chemical composition of the high-temperature resistant pressing plate is, by mass fraction, C: 0.03% to 0.04%, Si ≤ 0.75%, Mn ≤ 2.0%, P ≤ 0.045%, S ≤ 0.03%, Cr: 16.5% to 17.5%, Ni: 12.5% ​​to 13.5%, Mo: 2.8% to 3.2%, Ti: 0.4% to 0.6%, B: 0.003% to 0.005%, and the balance is Fe and unavoidable impurities; wherein, The mass fraction ratio of Ti to C is 8 to 10.

2. The high temperature resistant press plate according to claim 1, characterized in that: In the microstructure of the high temperature resistant pressed plate, the volume fraction of delta ferrite is less than 3%.

3. The high temperature resistant press plate according to claim 3, characterized in that: The microstructure further includes a TiC phase with a volume fraction of 3% to 5%, and the particle size of the TiC phase is 50nm to 80nm.

4. The high temperature resistant press plate according to claim 1, characterized in that: At 800° C., the high-temperature resistant press plate meets at least one of the following properties: a yield strength of 200 MPa to 220 MPa, and a thermal deformation of 0.1 mm to 0.12 mm within 100 hours.

5. The high temperature resistant press plate according to claim 1, characterized in that: The high temperature resistant pressing plate is suitable for a slab continuous casting and cutting process with a drawing speed of 1.7 m / min to 2.2 m / min.

6. A method for preparing the high temperature resistant pressboard according to any one of claims 1 to 5, comprising: obtaining a steel ingot having the chemical composition; The steel ingot is sequentially heated, multi-directionally forged and solution treated to obtain a semi-finished high-temperature resistant press plate; The surface of the semi-finished high-temperature resistant pressed plate is strengthened to obtain a finished high-temperature resistant pressed plate.

7. The method according to claim 6, characterized in that The heating temperature is 1100° C. to 1150° C., and the heating insulation time is 120 min to 135 min.

8. The method according to claim 6, characterized in that The deformation amount of the multi-directional forging is ≥60%, and the final forging temperature of the multi-directional forging is ≥900°C.

9. The method according to claim 6, characterized in that The temperature of the solution treatment is 1080° C. to 1100° C., and the water quenching time of the solution treatment is 90 min to 105 min.

10. The method according to claim 6, characterized in that The surface strengthening of the semi-finished high temperature resistant pressed plate to obtain a finished high temperature resistant pressed plate comprises: The working area of ​​the semi-finished high-temperature resistant press plate is subjected to laser cladding WC-10Co coating treatment, and the non-working area of ​​the semi-finished high-temperature resistant press plate is subjected to shot peening treatment to obtain a finished high-temperature resistant press plate.

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