Cyclic heating, induction hardened wear-resistant steel plate and preparation method and preparation device

Abstract

The application discloses a special wear-resistant steel plate for engineering machinery with cyclic heating and induction quenching, and chemical component content of the wear-resistant steel plate is as follows: C: 0.26-0.31%, Si: 0.15-0.35%, Mn: 1.10-1.45%, P: less than or equal to 0.010%, S: less than or equal to 0.003%, Ni: less than or equal to 0.30%, Cr: 0.30-0.60%, Mo: less than or equal to 0.30%, Cu: less than or equal to 0.30%, B: 0.0005%-0.0035%, and the rest is Fe and trace inevitable impurities; the thickness of the wear-resistant steel plate is 4-60 mm; the tensile strength of the wear-resistant steel plate ranges from 1550 MPa to 1700 MPa, the elongation is greater than or equal to 12, and the hardness ranges from 46 HRC to 52 HRC; the manufacturing method of the wear-resistant steel plate is novel and reasonable, and the wear-resistant steel plate has the excellent characteristics of uniform and stable mechanical properties, high wear resistance, high strength, impact resistance and weldability.

Description

Technical Field

[0001] This invention relates to the field of wear-resistant steel plate technology, and more specifically to wear-resistant steel plates subjected to cyclic heating and induction hardening, as well as their preparation methods and apparatus. Background Technology

[0002] Wear is one of the main failure modes of mechanical parts, and its impact is almost ubiquitous in the service life of industrial equipment in mining, metallurgy, building materials, and power industries. Wear results in a significant waste of materials and energy. According to incomplete statistics, wear on machinery and its parts accounts for 6% of the gross national product. Wear-resistant steel plates are key materials in the manufacture of equipment such as coal mining machinery, engineering machinery, port machinery, mining equipment, and dump trucks. In recent years, the increasing size and weight of equipment, coupled with increasingly harsh service environments, has led to ever-increasing demands on the performance requirements of steel plates.

[0003] Currently, the production of wear-resistant steel consumes a huge amount of electricity and has low thermal energy utilization. It also lacks the ability to automatically control the water spray area, flow rate, and pressure, thus failing to achieve precise quenching and guarantee the hardenability requirements of the steel plate. Wear-resistant steel plates are heated to the quenching temperature in the heating furnace through heat conduction, but the heating rate and core temperature uniformity affect the quenching effect. In conventional sequential heating furnaces, steel plates move slowly under the conveyor rollers. Due to limitations in furnace power and the heat capacity of the heated steel plates, it is difficult to guarantee the temperature and uniformity of the steel plate core, often resulting in serious quality problems such as poor flatness and steel plate distortion after quenching.

[0004] The purpose of this invention is to provide a wear-resistant steel plate that is cyclically heated and induction hardened, as well as its preparation method and apparatus, to overcome the shortcomings of the prior art. Summary of the Invention

[0005] To address the aforementioned problems and overcome the shortcomings of existing technologies, this invention provides a wear-resistant steel plate subjected to cyclic heating and induction hardening, along with its preparation method and apparatus.

[0006] To achieve the above objectives, the present invention provides a wear-resistant steel plate for engineering machinery that undergoes cyclic heating and induction hardening. The chemical composition of the wear-resistant steel plate, by weight percentage, is as follows:

[0007] C: 0.26-0.31%, Si: 0.15-0.35%, Mn: 1.10-1.45%, P≤0.010%, S≤0.003%, Ni≤0.30%, Cr: 0.30-0.60%, Mo≤0.30%, Cu≤0.30%, B: 0.0005%-0.0035%, with the remainder being Fe and trace amounts of unavoidable impurities.

[0008] Furthermore, the thickness of the wear-resistant steel plate is 4-60mm.

[0009] Furthermore, the tensile strength of the wear-resistant steel plate ranges from 1550 to 1700 MPa, the elongation is ≥12%, and the hardness ranges from 46 to 52 HRC.

[0010] Furthermore, the wear-resistant steel plate has an impact toughness value of ≥35J at -20℃.

[0011] A preparation method, comprising

[0012] Step (a) Smelting: Molten iron is pretreated by KR, smelted in a 120-ton converter, refined in a 120-ton ladle furnace, refined in a 120-ton vacuum degassing furnace, and produced by a slab continuous casting machine to obtain a continuously cast billet.

[0013] Step (b) Slow cooling of continuous casting billet: Slow cooling in the heat preservation pit for 72 hours, with the slow cooling temperature controlled at 350-650℃;

[0014] Step (c) Rolling: After the continuously cast billet is heated to 1200-1250℃, it is rolled in the austenite recrystallization zone and the non-recrystallization zone. The final rolling temperature in the austenite recrystallization zone is not lower than 1050℃, and the initial rolling temperature in the non-recrystallization zone is 965-990℃. The ratio between the thickness of the continuously cast billet and the thickness of the finished steel plate is not less than 3.

[0015] Step (d) Quenching heat treatment: The steel plate is heated to 880-900℃, and the furnace time is 1.1-1.4min / mm. The reciprocating cycle heating process is used to improve the heat energy utilization efficiency and effectively reduce the heating time. The induction quenching process is adopted. The water spray flow rate and pressure are adjusted according to the size of the induction steel plate to achieve rapid quenching to room temperature. The cooling rate is >40℃ / s.

[0016] Step (e) Tempering heat treatment: After induction hardening, the steel plate is heated to 210-230℃ for tempering treatment, and the tempering holding time is 2.0-3.0 min / mm.

[0017] Furthermore, in step (d) of the quenching heat treatment, the reciprocating heating process is as follows: the wear-resistant steel plate moves back and forth between heating zone one and heating zone two of the heating furnace. When the temperature in one zone drops to the specified limit during the heat transfer process, it moves to the other heating zone to continue heating until the specified time for the austenitization transformation of the steel plate is reached. Then, the steel plate is quickly transferred to the quenching zone through the furnace exit zone.

[0018] Furthermore, in step (d) of the induction hardening process during quenching heat treatment, the water flow rate and velocity per unit effective area are determined by collecting the length and thickness parameters of the wear-resistant steel plate.

[0019] A preparation apparatus includes a heating furnace and a quenching zone. The heating furnace includes a heating zone and a discharge zone. A detection zone is provided between the discharge zone and the quenching zone. The detection zone is equipped with a sensor A for collecting the length dimension parameter of the steel plate and a sensor B for collecting the thickness direction parameter of the steel plate.

[0020] The quenching zone includes an upper press and a lower press. The lower part of the upper press and the upper part of the lower press are each equipped with 16 water spray devices. Each water spray device includes a water inlet pipe and a high-pressure nozzle. An electric ball valve is installed between the water inlet pipe and the high-pressure nozzle. Both the upper press and the lower press are connected to water inlet pipes for supplying cold water.

[0021] The heating zone, unloading zone, testing zone, and quenching zone are set up sequentially from beginning to end;

[0022] The heating zone includes heating zone 1 and heating zone 2;

[0023] It also includes a roller mechanism, which is set along the heating zone, furnace exit zone, inspection zone and quenching zone.

[0024] Furthermore, the 16 water spray devices are arranged in the following order from beginning to end: numbered 15, 13, 11, 9, 7, 5, 3, 1, 2, 4, 6, 8, 10, 12, 14, and 16.

[0025] Furthermore, based on the length and thickness parameters of the wear-resistant steel plate, the on / off states of different numbered water spray devices are switched, and the opening angle of the electric ball valve is changed to determine the water flow rate obtained per meter of steel plate.

[0026] The beneficial effects of this invention are:

[0027] This invention studies wear-resistant steel plates specifically for engineering machinery. By changing the blade travel speed within the heating furnace's heating zone and employing reciprocating cyclic heating, the thermal energy utilization efficiency and the steel plate heating speed are improved. The induction hardening fixture is matched and adjusted according to the specific dimensions of the scanned steel plate to control the water supply area, water flow rate, and water pressure, further improving the hardenability, mechanical properties, and surface quality of the steel plate. This novel and reasonable manufacturing method for wear-resistant steel plates possesses excellent characteristics such as uniform and stable mechanical properties, high wear resistance, high strength, impact resistance, and weldability.

[0028] Circulating heating can effectively improve thermal energy utilization efficiency, reduce heating time, increase the heating rate of steel plates, and improve the uniformity of core temperature.

[0029] The induction hardening fixture is designed to match and adjust the water supply area, flow rate, and pressure of the steel plate according to its specific dimensions, further improving the hardenability, mechanical properties, and surface quality of the steel plate. This novel and reasonable method for manufacturing wear-resistant steel plates possesses excellent characteristics such as uniform and stable mechanical properties, high wear resistance, high strength, impact resistance, and weldability. It not only improves the hardenability, mechanical properties, and surface quality of the steel plate but also contributes to water conservation and environmental protection. This novel and reasonable heat treatment method realizes the design concept of quantitative supply, improving heat energy utilization efficiency and quenching effect. Attached Figure Description

[0030] Figure 1 This is a graph showing the temperature rise curve of the workpiece core during the cyclic heating and conventional heating processes of the present invention.

[0031] Figure 2 This is a comparison chart of hardenability data of steel plates in induction hardening and conventional hardening according to the present invention;

[0032] Figure 3 This is a comparison chart of measurement data on the effect of the cross press and ordinary press on the deformation of steel plates according to the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of the present invention;

[0034] Figure 5 This is a diagram showing the numbering and arrangement of the high-pressure nozzles in the quenching zone of the present invention;

[0035] In the attached diagram: 1. Heating furnace, 2. Roller mechanism, 3. Upper press, 4. Lower press, 5. Electric ball valve, 6. High-pressure nozzle, 7. Sensor A, 8. Sensor B, 9. Water inlet pipe, 10. Wear-resistant steel plate. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the following description will be provided in conjunction with the appendix of this invention. Figure 1 ~Appendix Figure 5 The present invention will be described in more detail below.

[0037] The wear-resistant steel plate for engineering machinery provided by this invention, which is subjected to cyclic heating and induction hardening, has the following chemical composition by weight percentage: C: 0.26-0.31%, Si: 0.15-0.35%, Mn: 1.10-1.45%, P≤0.010%, S≤0.003%, Ni≤0.30%, Cr: 0.30-0.60%, Mo≤0.30%, Cu≤0.30%, B: 0.0005%-0.0035%, with the remainder being Fe and trace amounts of unavoidable impurities;

[0038] in:

[0039] C: C is the most important alloying element in steel, and it has a significant impact on the strength, hardness, toughness, and hardenability of steel plates. Higher C content will increase the strength, hardness, and hardenability of steel, but will deteriorate its toughness. Therefore, in this invention, the C content is controlled at 0.26-0.31%.

[0040] Si: Si dissolves in ferrite and austenite in steel, significantly improving its strength and hardness. However, excessive Si content can easily lead to temper brittleness and reduce the toughness of the steel. Therefore, the Si content in this invention should be controlled within the range of 0.15-0.35%.

[0041] Mn: Mn can increase the toughness, strength, hardness, and hardenability of steel, and improve its hot working properties. The Mn content in this invention is controlled within the range of 1.10-1.45%.

[0042] P and S: P and S are harmful elements in steel, affecting its brittleness. S can form ductile inclusions (MnS) with manganese in steel, significantly impacting the transverse plasticity and toughness of the steel plate; simultaneously, P also severely affects the plasticity and toughness of the steel plate. For this invention, the lower the content of P and S, the better. However, in actual production processes, both P and S are unavoidable. Therefore, the P content in this invention is controlled below 0.010%, and the S content is controlled below 0.003%.

[0043] Mo: Mo can improve the tempering stability and hardenability of steel and prevent temper brittleness. In order to further improve the strength and wear resistance of steel, the Mo content in this invention is controlled at ≤0.30%.

[0044] Cr and Ni: Ni is the most important alloying element for improving the low-temperature toughness of steel. When Cr and Ni are added together, the hardenability of the steel can be increased several times over, ensuring that thick steel plates acquire a martensitic structure, thereby guaranteeing sufficiently high hardness. In this invention, the Cr content is controlled at 0.30-0.60%, and the Ni content is controlled at ≤0.30%.

[0045] B: B can combine with oxygen to form stable compounds, thereby reducing the gas content in steel. In addition, B can also improve the strength of steel through solid solution strengthening and grain refinement, and also has a positive effect on improving the impact toughness of steel plates. In this invention, the B content is controlled within the range of 0.0005% - 0.0035%.

[0046] The thickness of the wear-resistant steel plate is 4-60mm; the tensile strength of the wear-resistant steel plate ranges from 1550-1700MPa, the elongation is ≥12%, and the hardness ranges from 46-52HRC; the impact toughness of the wear-resistant steel plate is ≥35J under -20℃ conditions.

[0047] To prepare the aforementioned specific wear-resistant steel plate, a preparation method is provided, including:

[0048] Step (a) Smelting: Molten iron is pretreated by KR, smelted in a 120-ton converter, refined in a 120-ton ladle furnace, refined in a 120-ton vacuum degassing furnace, and produced by a slab continuous casting machine to obtain a continuously cast billet.

[0049] Step (b) Slow cooling of continuous casting billet: Slow cooling in the heat preservation pit for 72 hours, with the slow cooling temperature controlled at 350-650℃;

[0050] Step (c) Rolling: After the continuously cast billet is heated to 1200-1250℃, it is rolled in the austenite recrystallization zone and the non-recrystallization zone. The final rolling temperature in the austenite recrystallization zone is not lower than 1050℃, and the initial rolling temperature in the non-recrystallization zone is 965-990℃. The ratio between the thickness of the continuously cast billet and the thickness of the finished steel plate is not less than 3.

[0051] Step (d) Quenching heat treatment: The steel plate is heated to 880-900℃, and the furnace time is 1.1-1.4min / mm. The reciprocating cycle heating process is used to improve the heat energy utilization efficiency and effectively reduce the heating time. The induction quenching process is adopted. The water spray flow rate and pressure are adjusted according to the size of the induction steel plate to achieve rapid quenching to room temperature. The cooling rate is >40℃ / s.

[0052] Step (e) Tempering heat treatment: After induction hardening, the steel plate is heated to 210-230℃ for tempering treatment, and the tempering holding time is 2.0-3.0 min / mm.

[0053] The specific process of the reciprocating heating process described in step (d) quenching heat treatment is as follows: the wear-resistant steel plate moves back and forth in heating zone one to heating zone two of the heating furnace. When the temperature of one zone drops to the specified limit during the heat transfer process, it moves to the other heating zone to continue heating until the specified time for the austenitization transformation of the steel plate is reached. Then, the steel plate is quickly transferred to the quenching zone through the furnace exit zone.

[0054] As attached Figure 1 This study compared the core temperature variations of workpieces under two heating modes: conventional sequential heating and reciprocating cyclic heating. Conventional sequential heating involves adjusting the motor frequency and transmitting the steel plate at a relatively slow speed, making it insensitive to changes in furnace temperature. In contrast, reciprocating cyclic heating allows for higher frequency and speed transmission, enabling a more sensitive and timely response to furnace temperature changes. The core temperature curves during both cyclic and conventional heating processes show that the temperature rise during the reciprocating heating process is significantly greater than that during conventional sequential heating. This indicates that cyclic heating effectively improves thermal efficiency, reduces heating time, increases the heating rate of the steel plate, and enhances the uniformity of core temperature.

[0055] In step (d) of the quenching heat treatment, the induction hardening process determines the water flow rate and velocity per unit effective area by collecting the length and thickness parameters of the wear-resistant steel plate.

[0056] The core quenching effect of wear-resistant shovel blades is related to the overall mechanical properties of the steel plate. It requires a suitable cooling rate, and its microstructure transformation is from austenite to lath martensite, which is a continuous cooling microstructure transformation.

[0057] The critical temperature drop rate for the complete transformation of austenite to martensite is approximately 25℃ / s. By combining the specific heat capacity and cooling rate of the steel plate, quenching parameters for different steel plate thicknesses are obtained. The water consumption and spraying time are then determined based on these quenching parameters.

[0058]

[0059] According to the table above, different steel plate thicknesses require different water spraying times to achieve the critical temperature drop rate for the martensitic transformation of the steel plate. Based on the above data and by scanning the outline dimensions of the steel plate with a sensor, the obtained data, combined with the heat exchange rate, is used to match and adjust the water supply area and water flow rate of the steel plate.

[0060]

[0061] Based on the table above, the water supply area and flow rate are determined. The water flows through the spiral solid cone nozzle and the fan-shaped nozzle to be precisely sprayed onto the surface of the steel plate to achieve rapid cooling of the steel plate.

[0062] Hardness tests on the core of quenched steel plates showed that induction hardening technology offers a significant improvement over conventional hardening technology. (See attached...) Figure 2 The results show that the effect is more pronounced when the plate thickness reaches 50mm or more. This technology not only improves the hardening effect, mechanical properties, and surface quality of steel plates, but also saves water and protects the environment. This heat treatment method is novel and reasonable, realizing the design concept of quantitative supply, improving heat energy utilization efficiency and quenching effect. Controllable high-pressure water flow is used to achieve rapid quenching to room temperature, and the equipment's cooling rate capacity can reach up to 40℃ / s.

[0063] The specific performance data of steel plates obtained by induction hardening and conventional hardening are shown in the table below:

[0064]

[0065] To be applied to the above preparation method, a preparation apparatus is provided, including a heating furnace 1 and a quenching zone. The heating furnace 1 includes a heating zone and a furnace discharge zone. The heating zone includes a heating zone one and a heating zone two, both of which are equipped with heating tubes and temperature control sensors, enabling real-time monitoring of the furnace temperature.

[0066] During the quenching process, steel plates are affected by various factors, and the resulting dimensional deformation affects the machining accuracy and appearance quality of the blade. Severe deformation can even prevent the blade from being assembled.

[0067] The steel plate is in a semi-restricted free state within the gap between the traditional clamping plates, with small deformation. However, it is in a suspended state with large deformation at the end of the steel plate where the clamping plate cannot press down.

[0068] The upper press 3 and lower press 4 provided by this invention are equipped with cross-shaped pressure plates. This structure increases the frame density of the contact between the pressure plate and the steel plate, and does not affect the cooling and quenching effect of the water flow on the steel plate. The pressure plates of the upper press 3 and the lower press 4 are cross-shaped. The pressure plate of the lower press 4 is designed to be longitudinal, so as to bear the blades of different lengths. The upper pressure plate is designed to be transverse, which increases the contact frame density between the pressure ribs and the blades during water quenching and reduces the deformation of the blades during heat treatment.

[0069] Comparison of the flatness data of the steel plate around its perimeter and center using the two pressing methods shows that the cross-press technology effectively limits the deformation of the steel plate during quenching, controls the dimensional accuracy of the steel plate after quenching, saves subsequent straightening time, and improves the appearance quality of the wear-resistant shovel blade after spraying and packaging. Deformation data are attached. Figure 3 .

[0070] A detection zone is set between the furnace exit zone and the quenching zone. The detection zone is equipped with a sensor A7 for collecting the length dimension parameter of the steel plate and a sensor B8 for collecting the thickness direction parameter of the steel plate. The quenching zone includes an upper press 3 and a lower press 4. The lower part of the upper press 3 and the upper part of the lower press 4 are each equipped with 16 water spray devices. The water spray devices include a water inlet pipe and a high-pressure nozzle 6. An electric ball valve 5 is installed between the water inlet pipe and the high-pressure nozzle 6. The upper press 3 and the lower press 4 are both connected to a water inlet pipe 9 for supplying cold water.

[0071] The heating zone, unloading zone, testing zone, and quenching zone are set up sequentially from beginning to end;

[0072] It also includes a roller mechanism 2, which is arranged along the heating zone, the furnace exit zone, the detection zone and the quenching zone;

[0073] The 16 water spray devices are arranged in the following order from beginning to end: 15, 13, 11, 9, 7, 5, 3, 1, 2, 4, 6, 8, 10, 12, 14, and 16. Based on the length and thickness parameters of the wear-resistant steel plate 10, the on / off state of the water spray devices with different numbers is switched, and the opening angle of the electric ball valve 5 is changed to determine the water flow rate obtained per meter of steel plate.

[0074] The roller mechanism 2 rotates, and the heating zone rapidly transfers the steel plate from the furnace exit zone to the quenching zone. The quenching zone is equipped with an upper press 3 and a lower press 4, each containing 16 high-pressure nozzles 6. The high-pressure nozzles 6 include spiral solid cone nozzles and fan-shaped nozzles, and their opening and closing are controlled by electric ball valves 5.

[0075] Water inlet pipes 9 are installed on the upper press 3 and lower press 4 in the quenching zone to supply water to them. When the steel plate passes through the detection zone, sensors A7 and B8 are installed. Sensor A7 mainly collects the length dimension of the steel plate and, through a specific algorithm, determines whether the electric ball valve 5 inside the press is open or closed, thereby increasing the water flow rate and velocity per unit effective area. Sensor B8 mainly collects the thickness direction parameter of the steel plate and, through a specific algorithm, determines the opening angle of the electric ball valve 5 inside the press, thereby achieving precise water supply for different thicknesses.

[0076] The specific water spray area and the water flow rate per meter of steel plate have already been described, so they will not be repeated here.

[0077] The induction hardening fixture is designed to match and adjust the water supply area, flow rate, and pressure of the steel plate according to its specific dimensions, thereby further improving the hardenability, mechanical properties, and surface quality of the steel plate. This novel and reasonable manufacturing method for wear-resistant steel plate 10 exhibits excellent characteristics such as uniform and stable mechanical properties, high wear resistance, high strength, impact resistance, and weldability.

[0078] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0079] Example 1:

[0080] The chemical composition of wear-resistant steel plate 10 by weight percentage is C: 0.28%, Si: 0.17%, Mn: 1.20%, P: 0.010%, S: 0.003%, Ni: 0.30%, Cr: 0.30%, Mo: 0.30%, Cu: 0.30%, B: 0.0005%, with the remainder being Fe and trace amounts of unavoidable impurities. The wear-resistant steel plate has a thickness of 20mm and a length of 3000mm.

[0081] The preparation method of wear-resistant steel plate 10 is as follows:

[0082] Step (a) Smelting: Molten iron is pretreated by KR, smelted in a 120-ton converter, refined in a 120-ton ladle furnace, refined in a 120-ton vacuum degassing furnace, and produced by a slab continuous casting machine to obtain a continuously cast billet.

[0083] Step (b) Slow cooling of continuous casting billet: Slow cooling in the heat preservation pit for 72 hours, with the slow cooling temperature controlled at 350℃;

[0084] Step (c) Rolling: After the continuous casting billet is heated to 1200℃, it is rolled in the austenite recrystallization zone and the austenite non-recrystallization zone. The final rolling temperature in the austenite recrystallization zone is 1050℃, and the initial rolling temperature in the austenite non-recrystallization zone is 965℃. The ratio between the thickness of the continuous casting billet and the thickness of the finished steel plate is 3.

[0085] Step (d) Quenching heat treatment: The steel plate is heated to 880℃ using a reciprocating cycle heating process and the furnace time is 30min; induction quenching process is adopted, with high pressure nozzles 6 numbered 1 to 7 started, water spraying time is 106s, water consumption is 17732L, and cooling rate is 40℃ / s.

[0086] Step (e) Tempering heat treatment: After induction hardening, the steel plate is heated to 210℃ for tempering treatment, and the tempering holding time is 60min.

[0087] The 20mm thick wear-resistant steel plate obtained by the above process has a core hardness of HRC 49.5, a single-sided hardened layer depth of 10mm, and a hardening rate of 100.00%.

[0088] Example 2:

[0089] The chemical composition of wear-resistant steel plate 10 by weight percentage is C: 0.30%, Si: 0.30%, Mn: 1.45%, P: 0.001%, S: 0.003%, Ni: 0.25%, Cr: 0.50%, Mo: 0.25%, Cu: 0.25%, B: 0.0025%, with the remainder being Fe and trace amounts of unavoidable impurities. The wear-resistant steel plate has a thickness of 60mm and a length of 6000mm.

[0090] The preparation method of wear-resistant steel plate 10 is as follows:

[0091] Step (a) Smelting: Molten iron is pretreated by KR, smelted in a 120-ton converter, refined in a 120-ton ladle furnace, refined in a 120-ton vacuum degassing furnace, and produced by a slab continuous casting machine to obtain a continuously cast billet.

[0092] Step (b) Slow cooling of continuous casting billet: Slow cooling in the heat preservation pit for 72 hours, with the slow cooling temperature controlled at 600℃;

[0093] Step (c) Rolling: After the continuously cast billet is heated to 1250℃, it is rolled in the austenite recrystallization zone and the austenite non-recrystallization zone. The final rolling temperature in the austenite recrystallization zone is 1100℃, and the initial rolling temperature in the austenite non-recrystallization zone is 990℃. The ratio between the thickness of the continuously cast billet and the thickness of the finished steel plate is 3.5.

[0094] Step (d) Quenching heat treatment: The steel plate is heated to 900℃ using a reciprocating cycle heating process and the furnace time is 80min; induction quenching process is adopted, with high pressure nozzles 6 (numbered 1 to 16) started, water spraying time is 320s, water consumption is 53198L, and cooling rate is 40℃ / s.

[0095] Step (e) Tempering heat treatment: After induction hardening, the steel plate is heated to 230°C for tempering treatment, and the tempering holding time is 120 min.

[0096] The 60mm thick wear-resistant steel plate obtained by the above process has a core hardness of HRC 38.9, a single-sided hardened layer depth of 21.3mm, and a hardening rate of 71.00%.

[0097] Example 3:

[0098] The chemical composition of wear-resistant steel plate 10 by weight percentage is C: 0.29%, Si: 0.25%, Mn: 1.26%, P: 0.001%, S: 0.003%, Ni: 0.20%, Cr: 0.45%, Mo: 0.20%, Cu: 0.20%, B: 0.001%, with the remainder being Fe and trace amounts of unavoidable impurities. The wear-resistant steel plate has a thickness of 30mm and a length of 4000mm.

[0099] The preparation method of wear-resistant steel plate 10 is as follows:

[0100] Step (a) Smelting: Molten iron is pretreated by KR, smelted in a 120-ton converter, refined in a 120-ton ladle furnace, refined in a 120-ton vacuum degassing furnace, and produced by a slab continuous casting machine to obtain a continuously cast billet.

[0101] Step (b) Slow cooling of continuous casting billet: Slow cooling in the heat preservation pit for 72 hours, with the slow cooling temperature controlled at 550℃;

[0102] Step (c) Rolling: After the continuously cast billet is heated to 1220℃, it is rolled in the austenite recrystallization zone and the austenite non-recrystallization zone. The final rolling temperature in the austenite recrystallization zone is 1100℃, and the initial rolling temperature in the austenite non-recrystallization zone is 980℃. The ratio between the thickness of the continuously cast billet and the thickness of the finished steel plate is 3.3.

[0103] Step (d) Quenching heat treatment: The steel plate is heated to 890℃ using a reciprocating cycle heating process and the furnace time is 50min; induction quenching process is adopted, with high pressure nozzles 6 (numbered 1 to 10) started, water spraying time is 160s, water consumption is 26598L, and cooling rate is 40℃ / s.

[0104] Step (e) Tempering heat treatment: After induction hardening, the steel plate is heated to 220°C for tempering treatment, and the tempering holding time is 90 min.

[0105] The 30mm thick wear-resistant steel plate obtained by the above process has a core hardness of HRC 48.1, a single-sided hardening depth of 15mm, and a hardening rate of 100.00%.

[0106] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the scope and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for preparing wear-resistant steel plates for engineering machinery using cyclic heating and induction hardening, characterized in that: It includes a heating furnace and a quenching zone. The heating furnace includes a heating zone and a discharge zone. A detection zone is set between the discharge zone and the quenching zone. The detection zone is equipped with a sensor A for collecting the length dimension parameter of the steel plate and a sensor B for collecting the thickness direction parameter of the steel plate. The quenching zone includes an upper press and a lower press. The lower part of the upper press and the upper part of the lower press are each equipped with 16 water spray devices. Each water spray device includes a water inlet pipe and a high-pressure nozzle. An electric ball valve is installed between the water inlet pipe and the high-pressure nozzle. Both the upper press and the lower press are connected to water inlet pipes for supplying cold water. The heating zone, furnace exit zone, testing zone, and quenching zone are arranged sequentially from beginning to end; The heating zone includes heating zone 1 and heating zone 2; The upper and lower presses are equipped with cross-shaped pressure plates. This structure increases the frame density of the contact between the pressure plate and the steel plate, and does not affect the cooling and quenching effect of the water flow on the steel plate. The upper press plate and the lower press plate are cross-shaped, with the lower press plate designed to be longitudinal and the upper press plate designed to be transverse. The preparation apparatus also includes a roller mechanism, which is arranged along the heating zone, the furnace exit zone, the detection zone and the quenching zone; Based on the length and thickness parameters of the wear-resistant steel plate, the on / off states of different numbered water spray devices are switched, and the opening angle of the electric ball valve is changed to determine the water flow rate obtained per meter of steel plate.

2. The apparatus for preparing wear-resistant steel plates for engineering machinery by cyclic heating and induction hardening according to claim 1, characterized in that: The 16 water spray devices are arranged in the following order from beginning to end: numbered 15, 13, 11, 9, 7, 5, 3, 1, 2, 4, 6, 8, 10, 12, 14, and 16.

3. A method for preparing wear-resistant steel plates for engineering machinery using cyclic heating and induction hardening, applied to the apparatus for preparing wear-resistant steel plates for engineering machinery using cyclic heating and induction hardening as described in claim 1, characterized in that: include Step (a) Smelting: Molten iron is pretreated by KR, smelted in a 120-ton converter, refined in a 120-ton ladle furnace, refined in a 120-ton vacuum degassing furnace, and then processed by a slab continuous casting machine to produce a continuously cast billet. Step (b) Slow cooling of continuous casting billet: Slow cooling in the heat preservation pit for 72 hours, with the slow cooling temperature controlled at 350-650℃; Step (c) Rolling: After the continuously cast billet is heated to 1200-1250℃, it is rolled in the austenite recrystallization zone and the non-recrystallization zone. The final rolling temperature in the austenite recrystallization zone is not lower than 1050℃, and the initial rolling temperature in the non-recrystallization zone is 965-990℃. The ratio between the thickness of the continuously cast billet and the thickness of the finished steel plate is not less than 3. Step (d) Quenching heat treatment: The steel plate is heated to 880-900℃, and the furnace time is 1.1-1.4min / mm. The reciprocating cycle heating process is used to improve the heat energy utilization efficiency and effectively reduce the heating time. The induction quenching process is adopted. The water spray flow rate and pressure are adjusted according to the size of the induction steel plate to achieve rapid quenching to room temperature. The cooling rate is >40℃ / s. Step (e) Tempering heat treatment: After induction hardening, the steel plate is heated to 210-230℃ for tempering treatment, and the tempering holding time is 2.0-3.0 min / mm.

4. The method for preparing wear-resistant steel plates for engineering machinery by cyclic heating and induction hardening according to claim 3, characterized in that: The reciprocating heating process described in step (d) quenching heat treatment is as follows: the wear-resistant steel plate moves back and forth in heating zone 1 to heating zone 2 of the heating furnace. When the temperature of one zone drops to the specified limit during the heat transfer process, it moves to another heating zone to continue heating until the specified time for the austenitization transformation of the steel plate is reached. Then, the steel plate is quickly transferred to the quenching zone through the furnace exit zone.

5. The method for preparing wear-resistant steel plates for engineering machinery by cyclic heating and induction hardening according to claim 3, characterized in that: In step (d) of the quenching heat treatment, the induction hardening process determines the water flow rate and velocity per unit effective area by collecting the length dimension parameters and thickness direction parameters of the wear-resistant steel plate.

6. A wear-resistant steel plate for engineering machinery subjected to cyclic heating and induction hardening, based on the preparation method of the wear-resistant steel plate for engineering machinery subjected to cyclic heating and induction hardening as described in claim 3, characterized in that: The chemical composition of the wear-resistant steel plate, by weight percentage, is as follows: C: 0.26-0.31%, Si: 0.15-0.35%, Mn: 1.10-1.45%, P≤0.010%, S≤0.003%, Ni≤0.30%, Cr: 0.30-0.60%, Mo≤0.30%, Cu≤0.30%, B: 0.0005%-0.0035%, with the remainder being Fe and trace amounts of unavoidable impurities.

7. The wear-resistant steel plate for engineering machinery subjected to cyclic heating and induction hardening according to claim 6, characterized in that: The thickness of the wear-resistant steel plate is 4-60mm.

8. The wear-resistant steel plate for engineering machinery subjected to cyclic heating and induction hardening according to claim 6, characterized in that: The wear-resistant steel plate has a tensile strength range of 1550-1700MPa, an elongation of ≥12%, and a hardness range of 46-52HRC.

9. The wear-resistant steel plate for engineering machinery subjected to cyclic heating and induction hardening according to claim 6, characterized in that: The wear-resistant steel plate has an impact toughness value of ≥35J at -20℃.

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