Single-sided wear-resistant steel plate and induction heat treatment method thereof

Abstract

The application discloses a single-sided wear-resistant steel plate and an induction heat treatment method thereof, and comprises the following steps: S1, arranging a lower steel plate on a conveying roller way and stacking an upper steel plate on the upper surface of the lower steel plate; S2, arranging a vertical pinch roll on the conveying roller way so that the two side edges of the upper steel plate and the lower steel plate are aligned; S3, arranging a horizontal pinch roll on the conveying roller way behind the vertical pinch roll so that the contact surfaces of the upper steel plate and the lower steel plate are attached; S4, arranging an induction heating furnace on the conveying roller way behind the horizontal pinch roll so that the temperature of the upper surface of the upper steel plate and the lower surface of the lower steel plate is raised to a quenching temperature; and S5, arranging a cooler on the conveying roller way behind the induction heating furnace so that the temperature of the upper surface of the upper steel plate and the lower surface of the lower steel plate is cooled to room temperature. The application solves the problem that the strength (hardness) and plasticity (toughness) of the wear-resistant steel plate cannot be well matched.

Description

Technical Field

[0001] This invention relates to the manufacturing technology of wear-resistant steel plates, and more specifically, to a single-sided wear-resistant steel plate and its induction heat treatment method. Background Technology

[0002] In the iron and steel metallurgical industry, wear-resistant steel plate manufacturing technology has received widespread attention from the world's leading manufacturing countries in recent decades. Large steel companies both domestically and internationally are vigorously developing various high-performance, low-cost large-scale manufacturing technologies for wear-resistant steel plates based on their own specific circumstances. In my country, high-strength wear-resistant steel plates for engineering machinery, according to the national standard GB / T24186-2009, have formed a series of grades with progressively increasing hardness, ranging from NM300 to NM600. Essentially, most of these are low-alloy high-strength steels formed by adding 1% to 3% of alloying elements such as Cr, Ni, and Mo to ordinary carbon steel with a carbon content of 0.1–0.25%, and then continuously cast and rolled into slabs. After being directly quenched and tempered, or strengthened by controlled rolling and controlled cooling process (TMCP), this type of wear-resistant steel plate generally has the characteristics of high hardness and high strength. At the same time, it has good processing performance such as welding, bending and cutting, and excellent wear resistance. Its service life is several times that of traditional structural steel plates. In addition, due to the adoption of continuous large-scale production process, energy and resource consumption are saved, and the cost of steel plates is low. It can provide slabs for the manufacture of large-diameter UOE welded pipes for oil / natural gas medium transportation. It can also be widely used in various occasions where wear resistance is required in the form of abrasive wear, such as various silos and hoppers in blast furnace ironmaking and various dump truck bodies in engineering machinery.

[0003] To further improve the wear resistance of steel plates, as in Chinese patent application 201711059591.X, more alloying elements such as Cr are added to the chemical composition of conventional wear-resistant steel plates to increase the hardness and strength of the steel plates. However, this method of increasing alloy content not only increases material costs but also makes the continuous casting and rolling process more difficult. For example, Chinese patent application 201810126521.X uses air cooling instead of online quenching after final rolling to increase the martensite content in the steel plate. However, obtaining this more martensite is based on the premise that the high manganese steel (Mn content: 5.3-6.5%) has high hardenability. Therefore, currently, offline quenching and tempering are more commonly used for hot-rolled steel plates to optimize their overall performance. For example, Chinese patent application 201810147766.0 addresses the issue of plate shape after quenching by using a low-temperature quenching process through segmented heating in a heating furnace and regulation of quenching cooling water. Traditional heating furnace quenching has low heating efficiency and drawbacks such as surface decarburization, furnace gas pollution, and large equipment footprint. Chinese patent application 200580003011.4 uses induction heating for quenching of steel plates. However, existing heating furnaces or induction furnaces generally perform full-thickness heating and quenching of steel plates. When adjusting the strength (hardness) of the steel plate, it is constrained by various factors such as plasticity (toughness) and even plate shape, resulting in a limited adjustment range. This often fails to meet the actual needs of wear-resistant steel plates that require both surface wear resistance and structural strength and toughness. In addition, Chinese patent application 201120506806.X describes the overlaying of a high-chromium alloy wear-resistant layer on heat-resistant steel plates or stainless steel plates, and Chinese patent application CN201210357384.3 describes the sealing welding of ordinary steel materials and wear-resistant steel materials with a vacuum electron beam. This composite wear-resistant steel plate technology is complex, inefficient, and costly.

[0004] Therefore, actively seeking ways to improve the wear resistance of steel plates, or more specifically, how to accurately improve the wear resistance of the working side of the steel plate while also improving the plasticity and toughness of the non-working side, and ideally achieving large-scale, continuous, and efficient production, as well as green, energy-saving, and environmentally friendly low-cost heat treatment technologies, is undoubtedly of great value and importance for promoting the development of new wear-resistant steel plates, improving their performance, reducing their cost, and facilitating their application. Summary of the Invention

[0005] In view of the above-mentioned defects in the existing technology, the purpose of this invention is to provide a single-sided wear-resistant steel plate and its induction heat treatment method, so as to solve the problem that the strength (hardness) and plasticity (toughness) of the wear-resistant steel plate cannot be well matched.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] On one hand, an induction heat treatment method for a single-sided wear-resistant steel plate includes the following steps:

[0008] S1. Arrange the lower steel plate on the conveyor roller table, and stack the upper steel plate on the upper surface of the lower steel plate;

[0009] S2. Vertical pinch rollers are arranged on the conveyor roller table to align the two sides of the upper steel plate and the lower steel plate.

[0010] S3. A horizontal pinch roller is arranged on the conveyor roller table behind the vertical pinch roller so that the contact surfaces of the upper steel plate and the lower steel plate are in contact.

[0011] S4. An induction heating furnace is arranged on the conveying roller table behind the horizontal pinch roller to raise the temperature of the upper surface of the upper steel plate and the lower surface of the lower steel plate to the quenching temperature.

[0012] S5. A cooler is arranged on the conveyor roller behind the induction heating furnace to cool the temperature of the upper surface of the upper steel plate and the lower surface of the lower steel plate to room temperature.

[0013] Preferably, in step S1, the widths of the upper steel plate and the lower steel plate are the same;

[0014] The conveying speed V of the conveying roller conveyor is 1 to 10 m / min.

[0015] Preferably, in step S2, the number of vertical pinch rollers is at least one pair.

[0016] Preferably, in step S3, the number of horizontal pinch rollers is at least one pair.

[0017] Preferably, in step S4, the number of induction heating furnaces is at least one set;

[0018] The power supply P of the induction heating furnace is 1000-10000kW, and the frequency f is 1-50kHz.

[0019] Preferably, the induction coils in the induction heating furnace are arranged in a spiral shape parallel to the surfaces of the upper and lower steel plates; or

[0020] The surfaces perpendicular to the upper and lower steel plates are arranged in a spiral shape.

[0021] Preferably, in step S5, the number of coolers is at least one set.

[0022] Preferably, the cooling nozzles in the cooler are arranged in a spiral pattern parallel to the surfaces of the upper and lower steel plates; or

[0023] The surfaces perpendicular to the upper and lower steel plates are arranged in a spiral shape.

[0024] On the other hand, a single-sided wear-resistant steel plate is prepared by the aforementioned induction heat treatment method.

[0025] Preferably, the hardness of 1 / 4 to 1 / 2 of the thickness of the upper surface of the upper steel plate and the lower surface of the lower steel plate is 40 to 50 HRC.

[0026] The hardness of the lower surface of the upper steel plate and the upper surface of the lower steel plate, which is 1 / 2 to 3 / 4 of the thickness, is 20 to 30 HRC.

[0027] The single-sided wear-resistant steel plate and its induction heat treatment method provided by this invention have the following beneficial effects:

[0028] 1) Due to the use of medium and high frequency electromagnetic induction heating, compared with existing heating furnaces and other methods, the heating speed is faster, the grain structure is refined, the quenching depth is precisely controlled, the quenching quality and performance are high, and problems such as decarburization and environmental pollution are avoided.

[0029] 2) Because two steel plates are used for induction heat treatment at the same time, the heat treatment efficiency is increased by 100% compared with the existing heat treatment of a single steel plate, and the production efficiency is increased even more compared with the existing heat treatment lines such as heating furnaces, thus significantly reducing the production cost of wear-resistant steel plates.

[0030] 3) Due to the use of multiple sets of clamping rollers and the pressing action of multiple steel plates, the wear-resistant steel plate on one side has small deformation after heat treatment and good plate shape quality. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the on-site deployment of the induction heat treatment method of the present invention;

[0032] Figure 2 yes Figure 1 A top-down view;

[0033] Figure 3 This is a schematic diagram of the single-sided wear-resistant steel plate of the present invention;

[0034] Figure 4 This is a schematic diagram of an application embodiment of the single-sided wear-resistant steel plate of the present invention, wherein (a) is a steel pipe, (b) is a hopper, and (c) is a carriage. Detailed Implementation

[0035] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] Combination Figures 1 to 3As shown, the induction heat treatment method for a single-sided wear-resistant steel plate provided by the present invention includes the following steps:

[0037] S1. The lower steel plate 2 is arranged on the conveyor roller 5, and the upper steel plate 1 is stacked on the upper surface of the lower steel plate 2. The upper steel plate 1 and the lower steel plate 2 have the same width, but their thicknesses can be different. The longitudinal transmission power is provided by the belt-driven conveyor roller 5.

[0038] S2. Along the transmission direction of the conveying roller table 5, at least one pair of vertical pinch rollers 7 are arranged on the conveying roller table 5. The two sides of the upper steel plate 1 and the lower steel plate 2 are aligned and the center line position of the conveying roller table 5 is maintained. The vertical pinch rollers 7 need a certain clamping force and can adjust the roller gap between the two vertical pinch rollers 7 within a certain range to ensure that the vertical pinch rollers 7 and the steel plate are in contact during the transmission process, but do not stop the longitudinal movement of the steel plate.

[0039] S3. Along the conveying direction of the conveying roller table 5, at least one pair of horizontal pinch rollers 6 are arranged on the conveying roller table 5 behind the vertical pinch roller 7 to make the two contact surfaces of the upper steel plate 1 and the lower steel plate 2 in close contact, and to prevent various warping deformations that may exist before heat treatment or may occur after heat treatment. This also prevents these irregularly deformed steel plates from colliding or damaging the subsequent induction heating furnace 3, cooler 4, etc. during the conveying process. The horizontal pinch rollers 6 need a certain clamping force and can adjust the roller gap between the upper and lower horizontal pinch rollers 6 within a certain range to ensure that the upper steel plate 1 and the lower steel plate 2 maintain contact during the conveying process without blocking the longitudinal movement of the steel plate.

[0040] S4. Along the conveying direction of the conveying roller 5, at least one set of induction heating furnaces 3 are arranged on the conveying roller 5 behind the horizontal pinch roller 6 to rapidly raise the temperature of the upper surface of the upper steel plate 1 and the lower surface of the lower steel plate 2 to the quenching temperature.

[0041] S5. Along the conveying direction of the conveying roller 5, at least one set of coolers 4 are arranged on the conveying roller 5 behind the induction heating furnace 3 to rapidly cool the temperature of the upper surface of the upper steel plate 1 and the lower surface of the lower steel plate 2 to near room temperature, thus completing the quenching heat treatment process.

[0042] The conveying speed V of the conveying roller 5 is 1 to 10 m / min.

[0043] The power supply P of the induction heating furnace 3 is 1000~10000kW, and the frequency f is 1~50kHz.

[0044] The principle of the induction heat treatment method of this invention is as follows: An induction heating furnace 3 is connected to an induction heating power supply. During operation, an electromagnetic coil with a solenoid structure made of copper tubing inside the furnace 3 is switched on with an alternating current at a frequency of f. As the alternating current flows through the copper tubing, a strong alternating magnetic field is formed at the center of the coil. After the steel plate enters the induction heating furnace 3, a large number of eddy currents are induced within a certain depth range on the upper surface 11 of the upper steel plate 1 and the lower surface 22 of the lower steel plate 2 due to the alternating magnetic field. These eddy currents generate Ohmic heat within the skin effect depth d of the steel plate surface, thereby rapidly raising the temperature of the steel plate surface layer to the austenitizing temperature Tq (generally, Tq = 920–980℃). At high temperatures, the surface material of the steel plate undergoes a transformation from ferrite to austenite and the formation of some carbides. The solution reaction is followed by water spray / mist cooling in the cooler 4. The surface temperature of the steel plate is rapidly reduced to a lower temperature Tc below the martensitic transformation temperature (generally Tc = 160~180℃) at a cooling rate greater than 50℃ / s, thus undergoing the transformation of austenite to martensite. This results in a quenched martensitic structure with high hardness and high wear resistance within the skin depth of the steel plate surface. Meanwhile, the thickness range of other parts retains the original hot-rolled structure with high plasticity and high toughness, mainly composed of ferrite, due to the less influence of heat conduction in the skin layer during the rapid induction heating process. By controlling the layered microstructure of the steel plate cross-section, the hardness of the cross-section is distributed in a gradient, which effectively solves the problem that the strength (hardness) and plasticity (toughness) of wear-resistant steel plates are difficult to improve simultaneously during traditional overall heat treatment.

[0045] The induction coil inside the induction heating furnace 3 can be arranged in a spiral shape parallel to the surface of the steel plate, or it can be arranged in a spiral shape perpendicular to the surface of the steel plate. It is recommended that the induction coil adopt a planar structure with two parts wound perpendicular to the surface of the steel plate, with separate upper and lower parts and independent power supply. The advantages of doing so include at least: the distance between the coil and the steel plate is adjustable, the electromagnetic heat conversion efficiency is high, and the number of spare parts for the coil is small.

[0046] The cooling nozzles inside the cooler 4 can be arranged in a spiral shape parallel to the surface of the steel plate, or they can be arranged in a spiral shape perpendicular to the surface of the steel plate. It is recommended that the cooling nozzles adopt a planar structure with two parts wound perpendicular to the surface of the steel plate, with independent water supply. The advantages of doing so include at least the following: the distance between the nozzle and the steel plate can be adjusted, the cooling intensity ratio between the upper and lower parts of the steel plate can be adjusted, and the deformation of the steel plate can be reduced.

[0047] Combined Figure 3 As shown, the present invention also provides a single-sided wear-resistant steel plate, which is prepared by the induction heat treatment method of the present invention.

[0048] After quenching, the hardness of 1 / 4 to 1 / 2 of the thickness of the upper surface 11 of the upper steel plate 1 and the lower surface 22 of the lower steel plate 2 is 40 to 50 HRC.

[0049] The hardness of the lower surface 12 of the upper steel plate 1 and the upper surface 21 of the lower steel plate 2, which is 1 / 2 to 3 / 4 of the thickness, is 20 to 30 HRC.

[0050] Example 1

[0051] The hot-rolled steel plate is 1.8m wide and 15mm thick, with an alloy grade of NM360. (1) The upper steel plate 1 and the lower steel plate 2 are stacked on the conveyor roller 5, V = 1m / min; (2) Two pairs of vertical pinch rollers 7 are arranged at intervals at the front end of the conveyor roller 5, and the two steel plates are gradually aligned on both sides during the conveying process of the conveyor roller 5; (3) The plates are clamped by a pair of horizontal pinch rollers 6 arranged in front of the induction heating furnace 3 and behind the vertical pinch rollers 7; (4) The plates are induction heated by a set of induction heating furnace 3, P = 2000kW, f = 10kHz, d = 6mm; (5) The surface temperature of the steel plate is measured by an infrared thermometer, Tq = 920℃; (6) The plates are cooled by a set of coolers 4, with a cooling water flow rate of 40m3 / h and a pressure of 0.4MPa. The steel plate temperature Tc = 160℃ after exiting the cooler; (7) The plates are cooled naturally by the conveyor roller 5, the steel plate temperature drops to room temperature, the hardened surface is marked, and the plates are removed from the production line. The hardness of the upper surface 11 of the upper steel plate 1 and the lower surface 22 of the lower steel plate 2 within a thickness range of 6 mm after quenching treatment is 45 HRC, and the hardness of the lower surface 12 of the upper steel plate 1 and the upper surface 21 of the lower steel plate 2 within a thickness range of 9 mm is 25 HRC, which improves the performance of the wear-resistant steel plate.

[0052] Example 2

[0053] The hot-rolled steel plate is 1.8m wide and 15mm thick, with an alloy grade of NM500. (1) The upper steel plate 1 and the lower steel plate 2 are stacked on the conveyor roller 5, V = 10m / min; (2) Two pairs of vertical pinch rollers 7 are arranged at intervals at the front end of the conveyor roller 5, and the two steel plates are gradually aligned on both sides during the conveying process of the conveyor roller 5; (3) The plates are clamped by a pair of horizontal pinch rollers 6 arranged in front of the induction heating furnace 3 and behind the vertical pinch rollers 7; (4) The plates are induction heated by four sets of induction heating furnaces 3, P = 8000kW, f = 10kHz, d = 6mm; (5) The surface temperature of the steel plate is measured by an infrared thermometer, Tq = 960℃; (6) The plates are cooled by air mist by four sets of coolers 4, with a cooling water flow rate of 50m3 / h and a pressure of 0.4MPa. The steel plate temperature Tc = 160℃ after exiting the cooler; (7) The plates are cooled naturally by the conveyor roller 5 until the temperature drops to room temperature. The hardened surface is marked and the plates are removed from the production line. The hardness of the upper surface 11 of the upper steel plate 1 and the lower surface 22 of the lower steel plate 2 within a thickness range of 6 mm after quenching is 55 HRC, and the hardness of the lower surface 12 of the upper steel plate 1 and the upper surface 21 of the lower steel plate 2 within a thickness range of 9 mm is 30 HRC. This increases the quenching speed and improves the efficiency of the wear-resistant steel plate.

[0054] Example 3

[0055] The hot-rolled steel plate is 1.8m wide and 10mm thick, with an alloy grade of NM500. (1) The upper steel plate 1 and the lower steel plate 2 are stacked on the conveyor roller 5, V = 5m / min; (2) Two pairs of vertical pinch rollers 7 are arranged at intervals at the front end of the conveyor roller 5, and the two steel plates are gradually aligned on both sides during the conveying process of the conveyor roller 5; (3) The plates are clamped by a pair of horizontal pinch rollers 6 arranged in front of the induction heating furnace 3 and behind the vertical pinch rollers 7; (4) The plates are induction heated by two sets of induction heating furnaces 3, P = 4000kW, f = 40kHz, d = 3mm; (5) The surface temperature of the steel plate is measured by an infrared thermometer, Tq = 950℃; (6) The plates are cooled by air mist by two sets of coolers 4, with a cooling water flow rate of 40m3 / h and a pressure of 0.4MPa. The steel plate temperature Tc = 160℃ after exiting the cooler; (7) The plates are cooled naturally by the conveyor roller 5, and the temperature of the steel plate drops to room temperature. The hardened surface is marked and the plates are removed from the production line. The hardness of the upper surface 11 of the upper steel plate 1 and the lower surface 22 of the lower steel plate 2 within a 3mm thickness range after quenching is 55HRC, and the hardness of the lower surface 12 of the upper steel plate 1 and the upper surface 21 of the lower steel plate 2 within a 7mm thickness range is 30HRC. This reduces the thickness of the hardened layer and improves the overall performance of the wear-resistant steel plate.

[0056] Example 4

[0057] The quenched steel plate is 1.8m wide and 10mm thick, with alloy grade NM360 and original quenching depth of 3mm. (1) The upper steel plate 1 with its quenched surface facing up and the lower steel plate 2 with its quenched surface facing down are stacked on the conveyor roller 5, V = 1m / min; (2) Two pairs of vertical pinch rollers 7 are arranged at intervals at the front end of the conveyor roller 5, and the two steel plates are gradually aligned on both sides during the conveying process of the conveyor roller 5; (3) The plates are clamped by a pair of horizontal pinch rollers 6 arranged in front of the induction heating furnace 3 and behind the vertical pinch rollers 7; (4) The plates are induction heated by a set of induction heating furnace 3, P = 1000kW, f = 1kHz; (5) The surface temperature of the steel plate is measured by an infrared thermometer, Tq = 200℃; (6) The plates are naturally cooled by a set of coolers 4; (7) The plates are naturally cooled by the conveyor roller 5, and the temperature of the steel plate drops to room temperature and is removed from the production line. The hardness of the upper surface 11 of the upper steel plate 1 and the lower surface 22 of the lower steel plate 2 within a thickness of 3 mm after tempering is 44 HRC, and the hardness of the lower surface 12 of the upper steel plate 1 and the upper surface 21 of the lower steel plate 2 within a thickness of 7 mm is 25 HRC. This reduces the internal quenching stress of the steel plate and improves the shape quality and performance of the wear-resistant steel plate.

[0058] Example 5

[0059] Combination Figure 4As shown, the wear-resistant steel plate after quenching and tempering heat treatment is used to manufacture welded pipes, hoppers or dump truck bodies for media transportation. The wear-resistant surface (A surface) of the steel plate after quenching and hardening can effectively resist the friction and wear generated by the internal transported media (oil, gas, ore, slag).

[0060] In summary, the purpose of this invention is to increase the hardness of a steel plate within a certain depth range on one side, thereby enhancing its wear resistance. Simultaneously, it comprehensively improves the heat treatment quality and performance of wear-resistant steel plates, extending their service life. Furthermore, it increases heat treatment efficiency, making it green, energy-saving, and environmentally friendly. Increasing the hardness within a certain depth on the steel plate surface effectively enhances the surface wear resistance and the plate's inherent ductility and toughness, comprehensively improving the quality and performance of the wear-resistant steel plate. This results in good heat treatment plate shape, increased heat treatment efficiency, long service life, low cost, and a green, energy-saving, and environmentally friendly design. It has broad application prospects in the manufacture of wear-resistant welded pipes, silo hoppers, and truck body panels.

[0061] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method of induction heat treatment of a single-sided abrasion-resistant steel plate, characterized by, The method comprises the following steps: S1, arranging a lower steel plate on a conveying roller, and arranging an upper steel plate stack on the upper surface of the lower steel plate; S2, arranging vertical pinch rollers on the conveying roller to align the two side edges of the upper steel plate and the lower steel plate; S3, arranging horizontal pinch rollers on the conveying roller behind the vertical pinch rollers to make the contact surfaces of the upper steel plate and the lower steel plate adhere to each other; S4, arranging induction heating furnaces on the conveying roller behind the horizontal pinch rollers to raise the temperature of the upper surface of the upper steel plate and the lower surface of the lower steel plate to quenching temperature; The induction coils in the induction heating furnaces are arranged in a spiral shape parallel to the surfaces of the upper steel plate and the lower steel plate, or are arranged in a spiral shape perpendicular to the surfaces of the upper steel plate and the lower steel plate; S5, arranging coolers on the conveying roller behind the induction heating furnaces to cool the temperature of the upper surface of the upper steel plate and the lower surface of the lower steel plate to room temperature, The cooling nozzles in the coolers are arranged in a spiral shape parallel to the surfaces of the upper steel plate and the lower steel plate, or are arranged in a spiral shape perpendicular to the surfaces of the upper steel plate and the lower steel plate.

2. The method of induction heat treatment of a single-sided abrasion-resistant steel plate according to claim 1, characterized in that: In the step S1, the width of the upper steel plate and the lower steel plate is consistent. The conveying speed V of the conveying roller is 1-10 m / min.

3. The method of induction heat treatment of a single-sided abrasion-resistant steel plate according to claim 1, characterized in that: In the step S2, the number of the vertical pinch rollers is at least one pair.

4. The method of induction heat treatment of a single-sided abrasion-resistant steel plate according to claim 1, characterized in that: In the step S3, the number of the horizontal pinch rollers is at least one pair.

5. The method of induction heat treatment of a single-sided abrasion-resistant steel plate according to claim 1, characterized in that: In the step S4, the number of the induction heating furnaces is at least one group. The power P of the power supply of the induction heating furnaces is 1000-10000 kW, and the frequency f is 1-50 kHz.

6. The method of induction heat treatment of a single-sided abrasion-resistant steel plate according to claim 1, characterized in that: In the step S5, the number of the coolers is at least one group.

7. A single-sided abrasion-resistant steel plate, characterized by: The method is prepared by the induction heat treatment method according to any one of claims 1-6.

8. The single-sided abrasion-resistant steel plate according to claim 7, characterized in that: The hardness of the upper surface of the upper steel plate to the range of 1 / 4-1 / 2 thickness and the hardness of the lower surface of the lower steel plate to the range of 1 / 4-1 / 2 thickness are both 40-50 HRC; The hardness of the lower surface of the upper steel plate to the range of 1 / 2-3 / 4 thickness and the hardness of the upper surface of the lower steel plate to the range of 1 / 2-3 / 4 thickness are both 20-30 HRC.

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