Ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle and its green preparation method

Abstract

This invention discloses a special ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle and its green preparation method. The chemical composition of the steel plate is as follows: C: 0.17~0.25%, Si: 0.15~0.40%, Mn: 0.90~1.50%, P≤0.012%, S≤0.002%, Al: 0.050~0.080%, Ni: 0.55~0.85%, Cr: 0.70~1.40%, Mo: 0.20~0.40%, Nb: 0.02~0.04%, B: 0.0008~0.0020%, Ca: 0.0010~0.0020%, H≤0.00020%, N≤0.0050%. The preparation method includes the following steps: smelting, continuous casting, slab heating, rolling, online quenching after rolling + residual heat tempering, and mechanical stress relief. The steel plate of this invention has the characteristics of high toughness at ultra-low temperatures, stable HBW 450 level hardness, and long-term wear resistance.

Description

Technical Field

[0001] This invention belongs to the field of wear-resistant steel technology, specifically relating to an ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle and its green preparation method. Background Technology

[0002] The Arctic mining environment is extreme, with temperatures reaching below -50°C year-round. The complex terrain of the mining area requires large mining trucks to withstand high-intensity impacts, wear, and low-temperature brittleness challenges, placing stringent requirements on the use of Brinell hardness HBW450 grade wear-resistant steel plates for key components such as the truck bed floor and side guards.

[0003] Existing wear-resistant steel plates typically employ a long production process of "hot rolling + offline quenching + tempering," which suffers from complex procedures, long production cycles, high energy consumption, and large carbon emissions. In ultra-low temperature environments, steel plates produced using traditional processes are also prone to insufficient toughness and high crack sensitivity, leading to shortened equipment lifespan and increased maintenance costs.

[0004] Relevant literature and the latest publicly available patent novelty search results show that currently published patents related to HBW450-grade wear-resistant steel plates all focus on performance optimization in normal temperature or general low temperature environments (-20℃ to -30℃), without addressing toughness design for ultra-low temperature environments below -50℃; furthermore, the manufacturing processes mostly adopt traditional long processes, without mentioning green production solutions such as "short processes + waste heat utilization". Currently, there is a technological gap in the development of dedicated HBW450-grade wear-resistant steel plate technology that addresses both the dual needs of "ultra-low temperature mining in the Arctic Circle" and "short-process green manufacturing".

[0005] Therefore, developing a special HBW450-grade wear-resistant steel plate and its preparation technology that combines high performance and green manufacturing characteristics with "ultra-low temperature performance meeting standards and short-process green production" has become a dual requirement for Arctic mining development and the green transformation of the steel industry. Summary of the Invention

[0006] To address the aforementioned technical problems in the existing technology, this invention provides a special ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle and its green preparation method.

[0007] In a first aspect of the invention, the main chemical composition of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle is optimized and controlled by weight percentage as follows: C: 0.17~0.25%, Si: 0.15~0.40%, Mn: 0.90~1.50%, P≤0.012%, S≤0.002%, Al: 0.050~0.080%, Ni: 0.55~0.85%, Cr: 0.70~1.40%, Mo: 0.20~0.40%, Nb: 0.02~0.04%, B: 0.0008~0.0020%, Ca: 0.0010~0.0020%, H≤0.00020%, N≤0.0050%, with the balance being Fe and unavoidable impurities.

[0008] Furthermore, the carbon equivalent (CEV) of the aforementioned ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle is controlled to be CEV≤0.68%.

[0009] Furthermore, the aforementioned ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle has an impact energy of ≥47J at -60℃.

[0010] In a second aspect of the present invention, the green preparation method of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle includes the following steps: (1) Smelting: The main chemical composition of the molten steel prepared by smelting is optimized and controlled by weight percentage as follows: C: 0.17~0.25%, Si: 0.15~0.40%, Mn: 0.90~1.50%, P≤0.012%, S≤0.002%, Al: 0.050~0.080%, Ni: 0.55~0.85%, Cr: 0.70~1.40%, Mo: 0.20~0.40%, Nb: 0.02~0.04%, B: 0.0008~0.0020%, Ca: 0.0010~0.0020%, H≤0.00020%, N≤0.0050%, and the carbon equivalent CEV is controlled to be ≤0.68%, with the balance being Fe and unavoidable impurities; (2) Continuous casting: Fully protected casting, continuous casting slabs are slowly cooled for more than 48 hours after leaving the line; (3) Slab heating: The heating temperature is controlled at 1170~1230℃, the heating time is controlled at 8~10min / cm based on the slab thickness, and the heat soaking time is controlled at ≥40min; (4) Rolling: The slab is rolled into steel plate using a two-stage controlled rolling process with two stands. In the roughing stage, the slab is fully recrystallized and controlled rolling at a high penetration mode of ≥1050℃. The thickness of the intermediate slab is controlled to be 3.0~5.0 times the thickness of the finished steel plate. In the finishing stage, the starting rolling temperature is controlled to be 920~980℃ and non-recrystallization controlled rolling is carried out. (5) Online quenching after rolling + residual heat tempering: After the rolled steel plate is pre-straightened, it immediately enters the ultra-fast cooling system and is quenched and cooled online at a cooling rate of not less than 30℃ / s. After cooling to 280~220℃, the cooling is stopped and the residual heat of the steel plate is used for heat preservation. The heat preservation time is controlled to be 40~120min to obtain the target multiphase structure of tempered martensite + 2~5% retained austenite; (6) Mechanical stress relief: After the structural transformation is completed, a straightening machine is used to perform mechanical stress relief treatment to homogenize and reduce the residual stress inside the steel plate.

[0011] Furthermore, in the above-mentioned green preparation method of ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle, in the smelting step, the molten iron is pretreated before the converter smelting, and the S content in the molten iron is controlled to be ≤0.005% and the P content is controlled to be ≤0.120%.

[0012] Furthermore, in the above-mentioned green preparation method of ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle, in the continuous casting step, a light reduction process is used, with the light reduction amount controlled at 5~6mm and the billet speed controlled at 1.0~1.3m / min.

[0013] Furthermore, in the above-mentioned green preparation method of ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle, in the rough rolling stage of the rolling step, the deformation rate of each pass is distributed according to the increasing distribution of each pass, and the deformation rate of the last 3 passes is controlled to be ≥15%; in the finish rolling stage of the rolling step, the deformation rate of each pass is distributed according to the decreasing distribution of each pass.

[0014] The ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle and its green preparation method of the present invention have the following advantages and beneficial effects: (1) Through the optimized control of chemical composition and the precise coordination of preparation process, an ideal multiphase structure of "tempered martensite + island-shaped retained austenite" was obtained, which significantly improved the impact energy of steel plate and ensured that steel plate has both ultra-low temperature high toughness (-60℃ impact energy ≥47J), stable HBW 450 level hardness and long-term wear resistance.

[0015] (2) The two key processes of "quenching" and "tempering" are combined into one, and the integrated ultra-short process of "online quenching + residual heat tempering" is adopted. This completely eliminates the traditional offline reheating quenching and tempering process, achieving the ultimate green manufacturing and realizing the goals of ultra-short process and extreme energy saving.

[0016] (3) After the "residual heat tempering" of heat treatment, the present invention introduces a mechanical method (rolling straightening) to eliminate stress. Through active stress control, the dimensional stability and fatigue resistance of the steel plate under ultra-low temperature impact load are significantly improved. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0018] The main chemical composition of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle provided by this invention is optimized and controlled by weight percentage as follows: C: 0.17~0.25%, Si: 0.15~0.40%, Mn: 0.90~1.50%, P≤0.012%, S≤0.002%, Al: 0.050~0.080%, Ni: 0.55~0.85%, Cr: 0.70~1.40%, Mo: 0.20~0.40%, Nb: 0.02~0.04%, B: 0.0008~0.0020%, Ca: 0.0010~0.0020%, H≤0.00020%, N≤0.0050%, with the balance being Fe and unavoidable impurities.

[0019] Preferably, the carbon equivalent CEV of the special ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle of the present invention is controlled to be ≤0.68% (C+Mn / 6+(Cr+V+Mo) / 5+(Ni+Cu) / 15). In this invention, no V and Cu elements are added to the steel plate, so the values ​​of V and Cu in the carbon equivalent CEV calculation are 0.

[0020] The green preparation method of ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle provided by this invention includes the following steps: (1) Smelting: Converter smelting is adopted, and double slag operation is used during smelting to reduce P content; through LF refining + RH vacuum treatment, harmful gases such as O, H, N and S content are reduced. The main chemical composition of the molten steel prepared by smelting is optimized and controlled by weight percentage as follows: C: 0.17~0.25%, Si: 0.15~0.40%, Mn: 0.90~1.50%, P≤0.012%, S≤0.002%, Al: 0.050~0.080%, Ni: 0.55~0.85%, Cr: 0.70~1.40%, Mo: 0.20~0.40%, Nb: 0.02~0.04%, B: 0.0008~0.0020%, Ca: 0.0010~0.0020%, H≤0.00020%, N≤0.0050%, and control the carbon equivalent CEV=C+Mn / 6+(Cr+V+Mo) / 5+(Ni+Cu) / 15≤0.68%, with the balance being Fe and unavoidable impurities.

[0021] (2) Continuous casting: Full protective casting is carried out using protective slag, combined with light reduction process, the light reduction is controlled at 5~6mm, the billet pulling speed is controlled at 1.0~1.3m / min, the control of the first and second cooling processes in the continuous casting process is strengthened, and the continuous casting slab is slowly cooled for more than 48 hours after leaving the line.

[0022] (3) Slab heating: Strictly control the atmosphere in the heating furnace, adopt micro-positive pressure control, control the heating temperature at 1170~1230℃, control the heating time based on the slab thickness at 8~10min / cm, and control the heat soaking time at ≥40min to ensure that the steel billet is heated evenly and thoroughly.

[0023] (4) Rolling: The slab is rolled into steel plate using a two-stage controlled rolling process with two stands. In the rough rolling stage, the high penetration mode fully recrystallized controlled rolling is carried out at ≥1050℃. The thickness of the intermediate slab is controlled to be 3.0~5.0 times the thickness of the finished steel plate. In the finishing rolling stage, the starting rolling temperature is controlled at 920~980℃, and non-recrystallized controlled rolling is carried out to complete the strain accumulation in the non-recrystallized zone.

[0024] (5) Online quenching after rolling + residual heat tempering: After the rolled steel plate is pre-straightened, it immediately enters the ultra-fast cooling system and is quenched and cooled online at a cooling rate of not less than 30℃ / s. After cooling to 280~220℃, the cooling is stopped and the residual heat of the steel plate is used for heat preservation. The heat preservation time is controlled to be 40~120min to obtain the target multiphase structure of tempered martensite + 2~5% retained austenite.

[0025] (6) Mechanical stress relief: After the structural transformation is completed, a straightening machine is used to perform mechanical stress relief treatment, which effectively homogenizes and reduces the residual stress inside the steel plate.

[0026] Preferably, in the roughing stage of the rolling process, the deformation rate of each pass is distributed in an increasing manner, and the deformation rate of each of the last three passes is controlled to be ≥15%.

[0027] Preferably, in the finishing rolling stage of the rolling process, the deformation rate of each pass is distributed in a decreasing manner to ensure the flatness of the steel plate.

[0028] The following detailed description of the present invention, in conjunction with specific embodiments, details the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle and its green preparation method.

[0029] Example 1 The main chemical composition of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle of Example 1 is optimized and controlled by weight percentage as follows: C: 0.20%, Si: 0.25%, Mn: 1.0%, P: 0.009%, S: 0.001%, Al: 0.065%, Ni: 0.75%, Cr: 1.0%, Mo: 0.25%, Nb: 0.025%, B: 0.0008%, Ca: 0.0012%, H: 0.00013%, N: 0.0035%, with the balance being Fe and unavoidable impurities.

[0030] The carbon equivalent (CEV) of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle in Example 1 is C+Mn / 6+(Cr+V+Mo) / 5+(Ni+Cu) / 15=0.66%.

[0031] The specific implementation process of the green preparation method of ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle in Example 1 is as follows: (1) Hot metal pretreatment: The S content in the hot metal entering the furnace is controlled to be ≤0.005% and the P content is controlled to be ≤0.120%.

[0032] (2) Smelting: The steel is produced by smelting in a converter + refining in LF + vacuum treatment in RH. The main chemical components of the steel are optimized and controlled by weight percentage as follows: C: 0.20%, Si: 0.25%, Mn: 1.0%, P: 0.009%, S: 0.001%, Al: 0.065%, Ni: 0.75%, Cr: 1.0%, Mo: 0.25%, Nb: 0.025%, B: 0.0008%, Ca: 0.0012%, H: 0.00013%, N: 0.0035%, with the balance being Fe and unavoidable impurities.

[0033] (3) Continuous casting: Full protective casting is adopted. The continuous casting slab is slowly cooled for more than 48 hours after it is removed from the line. The dimensions (thickness × width × length) of the continuous casting slab are 250mm × 1800mm × 3600mm.

[0034] (4) Slab heating: The heating temperature is 1170℃, the heating time is 200~250min, and the soaking time is not less than 40min.

[0035] (5) Rolling: The slab is rolled into a steel plate with a thickness of 14mm using a two-stage controlled rolling process with two stands. The roughing rolling start temperature is 1140℃, the roughing rolling finish temperature is 1085℃, the intermediate slab thickness is 50.0mm, the finishing rolling start temperature is 980℃, and the finishing rolling finish temperature is 878℃.

[0036] (6) Online quenching after rolling + residual heat tempering: After the rolled steel plate is pre-straightened, it immediately enters the ultra-fast cooling system and is quenched and cooled online at a cooling rate of 35℃ / s. The final cooling temperature of online quenching is 235℃. Then, the residual heat of the steel plate is used to keep it warm for 40~120min.

[0037] (7) Mechanical stress relief: Use a straightening machine for mechanical stress relief treatment.

[0038] Example 2 The main chemical composition of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle of Example 2 is optimized and controlled by weight percentage as follows: C: 0.19%, Si: 0.20%, Mn: 1.2%, P: 0.009%, S: 0.001%, Al: 0.060%, Ni: 0.65%, Cr: 0.9%, Mo: 0.30%, Nb: 0.03%, B: 0.0009%, Ca: 0.0014%, H: 0.00014%, N: 0.0040%, with the balance being Fe and unavoidable impurities.

[0039] The carbon equivalent (CEV) of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle in Example 2 is C+Mn / 6+(Cr+V+Mo) / 5+(Ni+Cu) / 15=0.67%.

[0040] The specific implementation process of the green preparation method of ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle in Example 2 is as follows: (1) Hot metal pretreatment: The S content in the hot metal entering the furnace is controlled to be ≤0.005% and the P content is controlled to be ≤0.120%.

[0041] (2) Smelting: The steel is produced by smelting in a converter + refining in LF + vacuum treatment in RH. The main chemical components of the steel are optimized and controlled by weight percentage as follows: C: 0.19%, Si: 0.20%, Mn: 1.2%, P: 0.009%, S: 0.001%, Al: 0.060%, Ni: 0.65%, Cr: 0.9%, Mo: 0.30%, Nb: 0.03%, B: 0.0009%, Ca: 0.0014%, H: 0.00014%, N: 0.0040%, with the balance being Fe and unavoidable impurities.

[0042] (3) Continuous casting: Full protective casting is adopted. The continuous casting slab is slowly cooled for more than 48 hours after it is removed from the line. The dimensions (thickness × width × length) of the continuous casting slab are 250mm × 1800mm × 3600mm.

[0043] (4) Slab heating: The heating temperature is 1200℃, the heating time is 200~250min, and the soaking time is not less than 40min.

[0044] (5) Rolling: The slab is rolled into a steel plate with a thickness of 16mm using a two-stage controlled rolling process with two stands. The roughing rolling start temperature is 1160℃, the roughing rolling finish temperature is 1097℃, the intermediate slab thickness is 65.0mm, the finishing rolling start temperature is 978℃, and the finishing rolling finish temperature is 880℃.

[0045] (6) Online quenching after rolling + residual heat tempering: After the rolled steel plate is pre-straightened, it immediately enters the ultra-fast cooling system and is quenched and cooled online at a cooling rate of 32℃ / s. The final cooling temperature of online quenching is 240℃, and then the residual heat of the steel plate is used to keep it warm for 40~120min.

[0046] (7) Mechanical stress relief: Use a straightening machine for mechanical stress relief treatment.

[0047] Example 3 The main chemical composition of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle of Example 3 is optimized and controlled by weight percentage as follows: C: 0.18%, Si: 0.18%, Mn: 1.1%, P: 0.009%, S: 0.001%, Al: 0.064%, Ni: 0.6%, Cr: 1.05%, Mo: 0.32%, Nb: 0.035%, B: 0.0011%, Ca: 0.0017%, H: 0.00013%, N: 0.0031%, with the balance being Fe and unavoidable impurities.

[0048] The carbon equivalent (CEV) of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle in Example 3 is C+Mn / 6+(Cr+V+Mo) / 5+(Ni+Cu) / 15=0.67%.

[0049] The specific implementation process of the green preparation method of ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle in Example 3 is as follows: (1) Hot metal pretreatment: The S content in the hot metal entering the furnace is controlled to be ≤0.005% and the P content is controlled to be ≤0.120%.

[0050] (2) Smelting: The steel is produced by smelting in a converter + refining in LF + vacuum treatment in RH. The main chemical components of the steel are optimized and controlled by weight percentage as follows: C: 0.18%, Si: 0.18%, Mn: 1.1%, P: 0.009%, S: 0.001%, Al: 0.064%, Ni: 0.6%, Cr: 1.05%, Mo: 0.32%, Nb: 0.035%, B: 0.0011%, Ca: 0.0017%, H: 0.00013%, N: 0.0031%, with the balance being Fe and unavoidable impurities.

[0051] (3) Continuous casting: Full protective casting is adopted. The continuous casting slab is slowly cooled for more than 48 hours after it is removed from the line. The dimensions (thickness × width × length) of the continuous casting slab are 250mm × 1800mm × 3600mm.

[0052] (4) Slab heating: The heating temperature is 1230℃, the heating time is 200~250min, and the soaking time is not less than 40min.

[0053] (5) Rolling: The slab is rolled into a steel plate with a thickness of 20mm using a two-stage controlled rolling process with two stands. The roughing rolling start temperature is 1180℃, the roughing rolling finish temperature is 1099℃, the intermediate slab thickness is 75.0mm, the finishing rolling start temperature is 975℃, and the finishing rolling finish temperature is 884℃.

[0054] (6) Online quenching after rolling + residual heat tempering: After the rolled steel plate is pre-straightened, it immediately enters the ultra-fast cooling system and is quenched and cooled online at a cooling rate of 31℃ / s. The final cooling temperature of online quenching is 241℃. Then, the residual heat of the steel plate is used to keep it warm for 40~120min.

[0055] (7) Mechanical stress relief: Use a straightening machine for mechanical stress relief treatment.

[0056] The wear resistance (Brinell hardness) and impact energy properties of the ultra-low temperature high-toughness wear-resistant steel plates for large Arctic mining trucks produced using Examples 1-3 of this invention were tested. The test results are shown in Table 1 below: Table 1. Results of Brinell hardness and impact energy tests on ultra-low temperature high-toughness wear-resistant steel plates for large mining trucks in the Arctic Circle. ; The Brinell hardness test conducted on the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle of the present invention was based on GB-T231.1-2018 "Metallic materials Brinell hardness test - Part 1 Test method"; the impact energy test was based on GB / T229-2020 "Metallic materials Charpy pendulum impact test method".

[0057] In summary, compared with the prior art, the ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle and its green preparation method of the present invention have the following advantages and beneficial effects: (1) This invention obtains an ideal multiphase structure of "tempered martensite + island-shaped retained austenite" through optimized control of chemical composition and precise coordination of preparation process. Tempered martensite structure ensures material strength and hardness and improves wear resistance. Island-shaped retained austenite helps to absorb energy, improve hardness and passivate cracks. Thus, through the synergistic effect of each phase in the structure of the special ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle, especially the phase transformation (TRIP effect) induced by retained austenite under impact load, the impact energy of the steel plate can be significantly improved, ensuring that the steel plate has ultra-low temperature high toughness (-60℃ impact energy ≥47J), stable HBW 450 level hardness and long-term wear resistance.

[0058] (2) This invention innovatively combines the two key processes of "quenching" and "tempering" into one, and adopts an integrated ultra-short process of "online quenching + residual heat tempering". It utilizes the residual heat after rolling and quenching to directly complete the microstructure control and tempering, completely eliminating the traditional offline reheating quenching and tempering process, realizing the ultimate green manufacturing, and achieving the goal of ultra-short process and extreme energy saving with reduced processes, reduced energy consumption, and low emissions.

[0059] (3) After the heat treatment “residual heat tempering”, the present invention introduces a mechanical method (rolling straightening) to eliminate stress. Through active stress control, the stress peaks in the core and surface of the plate are reliably and uniformly eliminated, which significantly improves the dimensional stability and fatigue resistance of the steel plate under ultra-low temperature impact load.

[0060] (4) This invention ensures excellent weldability of the steel plate by optimizing the low-carbon composition design and reducing the welding preheating temperature. It should be noted that, unless otherwise specified, the terms used herein have the meanings commonly understood by those skilled in the art. Furthermore, when a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum. Further, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple ranges are provided to describe features, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0061] It should also be noted that, in this document, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the present invention.

Claims

1. A type of ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle, characterized in that, The main chemical composition of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle is optimized and controlled by weight percentage as follows: C: 0.17~0.25%, Si: 0.15~0.40%, Mn: 0.90~1.50%, P≤0.012%, S≤0.002%, Al: 0.050~0.080%, Ni: 0.55~0.85%, Cr: 0.70~1.40%, Mo: 0.20~0.40%, Nb: 0.02~0.04%, B: 0.0008~0.0020%, Ca: 0.0010~0.0020%, H≤0.00020%, N≤0.0050%, with the balance being Fe and unavoidable impurities.

2. The ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle according to claim 1, characterized in that, The carbon equivalent (CEV) of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle is controlled to be CEV≤0.68%.

3. The ultra-low temperature high-toughness wear-resistant steel plate for large mining trucks in the Arctic Circle according to claim 1, characterized in that, The ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle has an impact energy of ≥47J at -60℃.

4. A green preparation method for ultra-low temperature high-toughness wear-resistant steel plates specifically for large mining trucks in the Arctic Circle, characterized in that, Includes the following steps: (1) Smelting: The main chemical composition of the molten steel prepared by smelting is optimized and controlled by weight percentage as follows: C: 0.17~0.25%, Si: 0.15~0.40%, Mn: 0.90~1.50%, P≤0.012%, S≤0.002%, Al: 0.050~0.080%, Ni: 0.55~0.85%, Cr: 0.70~1.40%, Mo: 0.20~0.40%, Nb: 0.02~0.04%, B: 0.0008~0.0020%, Ca: 0.0010~0.0020%, H≤0.00020%, N≤0.0050%, and the carbon equivalent CEV is controlled to be ≤0.68%, with the balance being Fe and unavoidable impurities; (2) Continuous casting: Fully protected casting, continuous casting slabs are slowly cooled for more than 48 hours after leaving the line; (3) Slab heating: The heating temperature is controlled at 1170~1230℃, the heating time is controlled at 8~10min / cm based on the slab thickness, and the heat soaking time is controlled at ≥40min; (4) Rolling: The slab is rolled into steel plate using a two-stage controlled rolling process with two stands. In the roughing stage, the slab is fully recrystallized and controlled rolling at a high penetration mode of ≥1050℃. The thickness of the intermediate slab is controlled to be 3.0~5.0 times the thickness of the finished steel plate. In the finishing stage, the starting rolling temperature is controlled to be 920~980℃ and non-recrystallization controlled rolling is carried out. (5) Online quenching after rolling + residual heat tempering: After the rolled steel plate is pre-straightened, it immediately enters the ultra-fast cooling system and is quenched and cooled online at a cooling rate of not less than 30℃ / s. After cooling to 280~220℃, the cooling is stopped and the residual heat of the steel plate is used for heat preservation. The heat preservation time is controlled to be 40~120min to obtain the target multiphase structure of tempered martensite + 2~5% retained austenite; (6) Mechanical stress relief: After the structural transformation is completed, a straightening machine is used to perform mechanical stress relief treatment to homogenize and reduce the residual stress inside the steel plate.

5. The green preparation method of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle according to claim 4, characterized in that, In the smelting process, the molten iron is pretreated before converter smelting to control the S content in the molten iron to ≤0.005% and the P content to ≤0.120%.

6. The green preparation method of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle according to claim 4, characterized in that, In the continuous casting process, a light reduction process is used, with the reduction amount controlled at 5~6mm and the billet pulling speed controlled at 1.0~1.3m / min.

7. The green preparation method of the ultra-low temperature high toughness wear-resistant steel plate for large mining trucks in the Arctic Circle according to claim 4, characterized in that, In the roughing stage of the rolling process, the deformation rate of each pass is distributed in an increasing manner, and the deformation rate of the last 3 passes is controlled to be ≥15%; in the finishing stage of the rolling process, the deformation rate of each pass is distributed in a decreasing manner.