Steel plate for the body of a large mining dump truck for use in extremely cold regions and its manufacturing method

Abstract

The present invention relates to a steel plate for the body of a dump truck for use in large mines in extremely cold regions. The steel plate is divided into two layers, a multi-layer steel plate and a base steel plate, and the multi-layer steel plate and the base steel plate are metallurgically bonded together. The chemical composition of the multi-layer steel plate is: C: 0.19-0.29 wt.%; Si: 0.15-0.75 wt.%; Mn: 0.55-1.55 wt.%; Cr: 0.10-0.70 wt.% ; P: ≦0.030wt.%; S: ≦0.010wt.%; Al: 0.010~0.060wt.%; B: 0.0005~0.0050wt.%; and Mo: 0.01~0.60wt.%, RE: 0.01~0.08wt.%, Nb: 0.005~0.060wt.%, V: 0.01~0.10wt.%, Ti: 0.005~0.060wt.% and the balance being Fe and unavoidable impurities; the chemical composition of the base steel plate is C: 0.08-0.13 wt.%; Si: 0.15-0.55 wt.%; Mn: 0.70-1.70 wt.%; Cr: 0.05-0.55 wt.%; Mo: 0.10-0.55 wt.%; Ni: 1.25-2.55 wt.%; P: ≦0.030 wt.%; The steel contains one or more of S: ≦0.010 wt.%; Al: 0.010-0.080 wt.%; B: 0.0005-0.0050 wt.%; RE: 0.01-0.08 wt.%, Nb: 0.005-0.060 wt.%, V: 0.01-0.10 wt.%, and Ti: 0.005-0.060 wt.%, with the balance being Fe and unavoidable impurities. This steel element composition design results in a multi-layer steel plate with high hardness, and the base steel plate has high hardness while also exhibiting excellent low-temperature toughness. The metallurgical bonding between the individual steel layers in the rolling process not only ensures the integrity of the steel plate but also allows the properties of each individual steel plate to be fully utilized, resulting in excellent overall mechanical performance for the composite steel plate. In addition, the carbon and alloying element contents are controlled and the carbon equivalent is reduced to ensure that the steel plate has excellent welding performance.

Description

[Technical Field]

[0001] The present invention relates to a steel plate and a manufacturing method thereof, and more particularly to a steel plate for the body of a large mining dump truck used in extremely cold regions and a manufacturing method thereof. [Background technology]

[0002] Wear-resistant steel plates are typically used in machinery and equipment in engineering, mining, cement production, ports, power generation and metallurgy, where working conditions are particularly severe and high wear resistance, high strength, high hardness and high toughness are required, such as scraper conveyors and dump truck bodies.

[0003] In particular, large mining dump trucks used in extremely cold regions require high overall performance, especially low-temperature performance, for their vehicle body materials due to the low working temperatures. Compared to conventional high-strength steels, low-alloy, high-strength wear-resistant steel plates for dump truck bodies have higher strength but poorer low-temperature toughness. At temperatures below -40°C, even below -60°C, the body steel plates, especially the bottom plate, are susceptible to fracture due to impact with ore. Furthermore, wear-resistant steel plates for the body have large dimensional specifications, making preheating difficult, and therefore require good weldability. Further research is ongoing to develop a material that can simultaneously meet the high wear resistance, high strength, high hardness, high toughness, and weldability requirements for the bodies of large mining dump trucks used in extremely cold regions. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to solve the above problems and provide a steel sheet for the body of a large mining dump truck in an extremely cold region, and a manufacturing method thereof. In this specification, the extremely cold environmental temperature refers to a temperature of -40°C or lower. The extremely cold region refers to an area where the environmental temperature is -40°C or lower. [Means for solving the problem]

[0005] To achieve the above object, the present invention provides a steel plate for the body of a large mining dump truck in arctic regions, which is divided into two layers, a multi-layer steel plate and a base steel plate, and the two layers are metallurgically bonded. Specifically, the chemical composition of the multi-layer steel plate is one or more of C: 0.19 to 0.29 wt.%; Si: 0.15 to 0.75 wt.%; Mn: 0.55 to 1.55 wt.%; Cr: 0.10 to 0.70 wt.%; P: ≦0.030 wt.%; S: ≦0.010 wt.%; Al: 0.010 to 0.060 wt.%; B: 0.0005 to 0.0050 wt.%; and Mo: 0.01 to 0.60 wt.%, RE: 0.01 to 0.08 wt.%, Nb: 0.005 to 0.060 wt.%, V: 0.01 to 0.10 wt.%, Ti: 0.005 to 0.060 wt.%, with the remainder being Fe and unavoidable impurities.

[0006] The chemical composition of the base steel plate is C:0.08~0.13wt.%;Si:0.15~0.55wt.%;Mn:0.70~1.70wt.%;Cr:0.05~0. 55wt.%;Mo:0.10~0.55wt.%;Ni:1.25~2.55wt.%;P:≦0.030wt.%;S:≦0.010wt.%;Al:0 0.010~0.080wt.%; B: 0.0005~0.0050wt.%; and one or more of RE: 0.01~0.08wt.%, Nb: 0.005~0.060wt.%, V: 0.01~0.10wt.%, Ti: 0.005~0.060wt.%, the balance being Fe and unavoidable impurities.

[0007] Therefore, by designing the above steel element composition, the multi-layer steel plate has high hardness, and the base steel plate has high hardness while also having excellent low-temperature toughness. In the steel plate composited by the rolling process, the steel plates of each layer are metallurgically bonded, which not only ensures the integrity of the steel plate but also allows the properties of each steel plate to be fully utilized, resulting in the composite steel plate having excellent overall mechanical performance as a whole. In addition, by controlling the content of carbon and alloying elements and reducing the carbon equivalent, the steel plate is ensured to have excellent welding performance.

[0008] Specifically, the principle of composition design of the steel plate for the body of the large-scale mining dump truck in the cold region according to the present invention is as follows: Carbon: Carbon is the most fundamental and important element in wear-resistant steels. It improves the strength and hardness of steel through solid solution strengthening and precipitation strengthening. Carbon is also an important element for obtaining a martensite structure. Too low a carbon content can prevent the steel from obtaining a bainite or martensite structure and the necessary mechanical properties and wear resistance. Too high a carbon content can increase the steel's tendency to segregate during continuous casting or die casting, resulting in severe segregation, reduced toughness, and unacceptable mechanical performance indexes. In the multi-layer steel plate of the present invention, the carbon content is controlled to 0.19-0.29 wt.%, preferably 0.20-0.29 wt.%, to ensure the strength and hardness of the steel plate. In the base steel plate, the carbon content is controlled to 0.08-0.13 wt.%, preferably 0.08-0.12 wt.%, to ensure the strength and hardness of the steel plate while also achieving toughness. In some embodiments, the carbon content in the multilayer steel plate according to the present invention is controlled to 0.20 to 0.28 wt.%.

[0009] Silicon: Suitable silicon is a beneficial deoxidizer in steel and can form easily floating calcium-aluminum silicate inclusions with calcium and aluminum in steel, improving the purity of the steel. Silicon dissolves in ferrite and austenite, improving their hardness and strength. However, excessive silicon content can lead to a rapid decrease in the toughness of steel. Therefore, in the multi-layer steel sheet of the present invention, the silicon content is controlled to 0.15-0.75 wt.%, preferably 0.20-0.75 wt.%; in the base steel sheet, the silicon content is controlled to 0.05-0.55 wt.%, preferably 0.10-0.50 wt.%. In some embodiments, in the multi-layer steel sheet of the present invention, the silicon content is controlled to 0.15-0.35 wt.%. In some embodiments, in the base steel sheet of the present invention, the silicon content is controlled to 0.20-0.45 wt.%.

[0010] Manganese: Manganese significantly improves the hardenability of steel and lowers its transition temperature and critical cooling rate. However, high manganese content tends to coarsen grains and increase the temper embrittlement susceptibility of steel. Furthermore, it is prone to segregation and cracking in cast billets, resulting in reduced steel sheet performance. Therefore, in the multi-layer steel sheet of the present invention, the Mn content is controlled to 0.55-1.55 wt.%, preferably 0.60-1.50 wt.%; in the base layer steel sheet, the Mn content is controlled to 0.70-1.70 wt.%, preferably 0.70-1.60 wt.%. In some embodiments, in the multi-layer steel sheet of the present invention, the Mn content is controlled to 0.65-1.00 wt.%. In some embodiments, in the base layer steel sheet of the present invention, the Mn content is controlled to 0.90-1.55 wt.%.

[0011] Chromium: Chromium can improve the hardenability of steel, thereby increasing its strength and hardness. Chromium can prevent or delay the precipitation and aggregation of carbides during tempering, improving the tempering stability of steel. Chromium can significantly improve corrosion resistance. Therefore, in the multilayer steel plate according to the present invention, the Cr content is controlled to 0.05-0.55 wt.%, preferably 0.10-0.55 wt.%; in the base layer steel plate, the Cr content is controlled to 0.15-0.55 wt.%, preferably 0.15-0.50 wt.%. In some embodiments, in the multilayer steel plate according to the present invention, the Cr content is controlled to 0.20-0.35 wt.%. In some embodiments, in the base layer steel plate according to the present invention, the Cr content is controlled to 0.15-0.25 wt.%.

[0012] Aluminum: Aluminum combines with nitrogen in steel to form fine, refractory AlN particles, thereby refining the grain size of the steel. Aluminum refines the grain size of the steel, immobilizes nitrogen and oxygen in the steel, reduces the notch sensitivity of the steel, reduces or eliminates the aging phenomenon of the steel, and improves the toughness of the steel. Therefore, in the multi-layer steel sheet according to the present invention, the Al content is controlled to 0.010 to 0.060 wt.%, preferably 0.015 to 0.060 wt.%; in the base steel sheet, the Al content is controlled to 0.010 to 0.080 wt.%, preferably 0.010 to 0.070 wt.%. In some embodiments, in the multi-layer steel sheet according to the present invention, the Al content is controlled to 0.030 to 0.055 wt.%. In some embodiments, in the base steel sheet according to the present invention, the Al content is controlled to 0.035 to 0.050 wt.%.

[0013] Boron: Adding trace amounts of boron to steel can significantly improve hardenability during quenching. However, if the boron content is too high, it tends to be unevenly distributed at grain boundaries, reducing grain boundary bond energy and causing fracture along the grain boundaries when the steel sheet is subjected to an impact load, thereby reducing the low-temperature impact absorption energy of the steel sheet. Therefore, in the multi-layer steel sheet according to the present invention, the B content is controlled to 0.0005 to 0.0050 wt.%, preferably 0.0010 to 0.0050 wt.%; in the base layer steel sheet, the B content is controlled to 0.0005 to 0.0050 wt.%, preferably 0.0005 to 0.0040 wt.%. In some embodiments, in the multi-layer steel sheet according to the present invention, the B content is controlled to 0.0015 to 0.0025 wt.%. In some embodiments, the content of B in the base layer steel sheet according to the present invention is controlled to B: 0.0010 to 0.0025 wt.%.

[0014] Among other elements, molybdenum: Molybdenum refines grains and improves strength and toughness. Molybdenum reduces temper embrittlement and improves temper stability. RE: RE refers to one or more rare earth elements, specifically one or more selected from La, Ce, and Nd. Adding rare earth elements to steel reduces the segregation of elements such as sulfur and phosphorus, improves the shape, size, and distribution of non-metallic inclusions, refines grains, strengthens grain boundaries, and improves hardness and toughness. Nickel: Nickel significantly lowers the low-temperature brittle transition temperature, but too high a content can make the surface oxide scale on steel sheets less likely to peel and significantly increase costs. Niobium: Niobium refines grains, improving strength and toughness. Titanium: Titanium is a strong carbide-forming element and forms fine TiC particles with carbon. The TiC particles are fine and distributed at the grain boundaries, where they have the effect of refining the grains, while the hard TiC particles improve the wear resistance of the steel. Therefore, the multi-layer steel plate according to the present invention contains one or more of Mo: 0.01-0.60 wt.%, RE: 0.01-0.08 wt.%, Nb: 0.005-0.060 wt.%, V: 0.01-0.10 wt.%, and Ti: 0.005-0.060 wt.%. The base steel plate contains one or more of Re: 0.01-0.08 wt.%, Nb: 0.005-0.060 wt.%, V: 0.01-0.10 wt.%, and Ti: 0.005-0.060 wt.%.

[0015] In some embodiments, in the multi-layered steel sheet according to the present invention, the Mo content is ≦0.20 wt.%, for example, 0.10 to 0.20 wt.%. In some embodiments, in the multi-layered steel sheet according to the present invention, the RE content is ≦0.05 wt.%, or no RE is contained. In some embodiments, in the multi-layered steel sheet according to the present invention, the Nb content is ≦0.030 wt.%, for example, 0.010 to 0.030 wt.%. In some embodiments, in the multi-layered steel sheet according to the present invention, the V content is ≦0.06 wt.%. In some embodiments, in the multi-layered steel sheet according to the present invention, the Ti content is ≦0.030 wt.%, for example, 0.010 to 0.030 wt.%.

[0016] In some embodiments, the multilayer steel sheet according to the present invention contains Mo: ≦0.20 wt.%; RE: ≦0.05 wt.%; Nb: 0.010 to 0.030 wt.%; V≦0.06 wt.%; and Ti: 0.010 to 0.030 wt.%.

[0017] In some embodiments, the RE content in the base steel sheet according to the present invention is ≦0.06 wt.%, for example, 0.02 to 0.06 wt.%. In some embodiments, the Nb content in the base steel sheet according to the present invention is ≦0.06 wt.%, for example, 0.010 to 0.030 wt.%. In some embodiments, the V content in the base steel sheet according to the present invention is ≦0.08 wt.%, for example, 0.04 to 0.08 wt.%. In some embodiments, the Ti content in the base steel sheet according to the present invention is ≦0.04 wt.%, for example, 0.01 to 0.035 wt.%.

[0018] In some embodiments, the base layer steel sheet according to the present invention contains RE: ≦0.06 wt.%; Nb: 0.010 to 0.030 wt.%; V: ≦0.08 wt.%; and Ti: 0.01 to 0.035 wt.%.

[0019] In some embodiments, the carbon equivalent Ceq of the multilayer steel plate according to the present invention is 0.40 to 0.50; the carbon equivalent Ceq of the base layer is 0.45 to 0.60; where Ceq = C + Mn / 6 + (Cr + Mo + V) / 5 + (Cu + Ni) / 15.

[0020] Phosphorus and sulfur: In wear-resistant steels, sulfur and phosphorus are both harmful elements, and their contents must be strictly controlled. In the steel type of the present invention, the phosphorus content is controlled to ≦0.030 wt.% and the sulfur content is controlled to ≦0.010 wt.%.

[0021] In one embodiment of the present invention, the steel plate for the body of a dump truck for use in a large mining operation in an extremely cold region according to the present invention comprises the above elements, Fe, and inevitable impurities. In another embodiment of the present invention, the steel plate for the body of a dump truck for use in a large mining operation in an extremely cold region according to the present invention contains the above elements, Fe, and inevitable impurities.

[0022] Preferably, the steel plate for the body of a dump truck for use in a large mine in an extremely cold region according to the present invention is a composite steel plate, and its typical mechanical properties are as follows: Typical mechanical properties of the multi-layer steel plate: Brinell hardness is 450 HBW or more (e.g., 450 to 540 HBW), and -60°C impact energy is 10 J or more, preferably 15 J or more, and more preferably 20 J or more (e.g., 10 to 35 J); Typical mechanical properties of the base layer steel plate: Brinell hardness is 300 HBW or more (e.g., 300 to 410 HBW or 330 to 410 HBW), and -60°C impact energy is 100 J or more, preferably 115 J or more, and preferably 120 J or more (e.g., 100 to 140 J). In the steel plate for the body of the dump truck for use in large mines in extremely cold regions, the microstructure of the multi-layer steel plate portion is martensite and a small amount of retained austenite, and the microstructure of the base steel plate portion is martensite or bainite and retained austenite.

[0023] In the steel plate for the body of a dump truck for use in a large mine in an extremely cold region according to the present invention, the metallurgical bond between the multi-layer steel plate and the base steel plate refers to a bond formed by mutual diffusion of atoms at the interface between the base layer and the multi-layer steel plate, which can be achieved by a general metallurgical bonding means, such as an explosive compounding process or a roll compounding process, and is preferably achieved by a roll compounding process.

[0024] In the steel plate for the body of a dump truck for use in a large mine in an arctic region according to the present invention, the thickness specification ratio of the base layer and the multi-layer steel plate is determined according to the demand for product performance. In one embodiment, the thickness of the multi-layer steel plate is 5 to 20 mm, more preferably 6 to 18 mm, and the thickness of the base layer steel plate is 6 to 15 mm, more preferably 8 to 14 mm.

[0025] The steel plate for the bodies of large mining dump trucks in extremely cold regions according to the present invention is obtained by controlling the chemical composition of the multi-layer steel plate and base steel plate, the combined rolling process and the heat treatment process, thereby obtaining a steel plate that is excellent in all of hardness, toughness, welding performance and mechanical processing performance, and can be applied to products such as steel plate for the bodies of large mining dump trucks in extremely cold regions.

[0026] The method for manufacturing a steel plate for a body of a large mining dump truck for use in extremely cold regions according to the present invention includes the following steps: (1) Through smelting and casting, multi-layer continuous casting billets and base layer continuous casting billets are formed; (2) Producing a composite stacked billet from a multi-layer continuous casting billet and a base layer continuous casting billet; (3) Slab heating and slab rolling of the composite stacked billet: In the heating process, the slab heating temperature is 1100-1250°C and is kept at this temperature for 1-3 hours. The stacked continuous cast slabs are rolled, with the rolling start temperature being 1000-1150°C, the rolling finish temperature being 880-980°C, and the finish rolling reduction being ≥ 50% (e.g., 55-85%). After rolling, the slabs are quenched online at room temperature to 200°C (e.g., 100-200°C), and tempering heat treatment may be performed as needed; the tempering temperature is 150-350°C (e.g., 150-280°C), and the keeping time is 3 x plate thickness (min), where the plate thickness is in mm. The plate thickness is the thickness of the rolled steel plate.

[0027] Preferably, the process for producing a composite stacked billet from the multi-layer continuous casting billet and the base layer continuous casting billet includes the following steps: (i) By using a mechanical method, the surface oxide layer on one side of the surfaces to be bonded of the multi-layer continuous casting billet and the base layer continuous casting billet is cleaned, and the four sides of the surface from which the surface oxide layer has been cleaned are beveled; (ii) The multi-layer continuous casting billet and the base layer continuous casting billet, the surfaces of which have been cleaned, are left to stand and bonded together so that the cleaned surface of the multi-layer continuous casting billet faces the cleaned surface of the base layer continuous casting billet; (iii) The mating surfaces of the multi-layer continuous casting billet and the base layer continuous casting billet are welded and sealed in four directions, and a vacuum channel is left at the edge, through which the welded and sealed composite stacked billet is subjected to a vacuum treatment, and then sealed to form a composite stacked billet.

[0028] In the method for manufacturing steel plates for bodies of large-scale mine dump trucks in arctic regions according to the present invention, the thickness specification ratio of the base layer continuous cast billet and the multi-layer continuous cast billet is determined according to the demands of product performance.

[0029] The steel plate for the body of a large mining dump truck for use in extremely cold regions according to the present invention has the following advantageous effects compared to the prior art: 1. From the viewpoint of chemical composition, the chemical composition of the composite steel plate of the present invention is mainly composed of medium-high carbon low alloys, and makes full use of the strong hardening effect of C and small amounts of alloying elements to improve the hardness of the steel plate while also improving the weldability of the steel plate; the chemical composition of the base steel plate is mainly composed of low carbon low alloys, and appropriate amounts of Mo, Ni, and alloying elements such as Nb, V, and Ti are added to improve the impact toughness of the steel plate while also improving the weldability of the steel plate. Due to the different chemical compositions of the base steel plate and the composite steel plate, the steel plate of the present invention has excellent toughness, weldability, mechanical workability, wear resistance, etc.

[0030] 2. In terms of the production process, two continuous cast billets are used to produce a composite stacked billet. By controlling process parameters such as heating temperature, rolling start and finish temperatures, rolling deformation amount, online quenching temperature, and tempering temperature, the structure is refined and the strengthening effect is improved, thereby reducing the carbon and alloying element content and obtaining a steel plate with excellent mechanical properties and wear resistance. At the same time, the metallurgical bonding between the base steel plate and the composite steel plate exerts a synergistic effect, ensuring the production of steel plate products.

[0031] 3. From the viewpoint of product performance, the steel plate for the body of a large mining dump truck for use in arctic regions according to the present invention has excellent toughness, with the typical mechanical properties of the multi-layer steel plate: impact energy at -60°C of 10J or more, preferably 15J or more, and more preferably 20J or more; and typical mechanical properties of the base steel plate: Brinell hardness of 300HB or more, impact energy at -60°C of 100J or more, preferably 115J or more, and preferably 120J or more. In the steel plate for the body of a large mining dump truck for use in arctic regions, in which the multi-layer and base layers are metallurgically bonded, the toughness of the base layer is transmitted to the entire steel plate through the metallurgical bond, ensuring that the entire steel plate is resistant to fracture, while the high hardness of the composite steel plate avoids and reduces damage caused by minerals.

[0032] 4. From the viewpoint of microstructure, in the steel plate for the body of the dump truck for large mining use in extremely cold regions according to the present invention, the microstructure of the multi-layer steel plate portion is martensite and a small amount of retained austenite, and the microstructure of the base steel plate portion is martensite or bainite and retained austenite.

[0033] In any case, the steel plate for the bodies of large mining dump trucks in extremely cold regions according to the present invention is a steel plate that is excellent in hardness, toughness, welding performance, and mechanical processing performance by controlling the chemical composition of the multi-layer steel plate and base steel plate, the combined rolling process, and the heat treatment process, and can be applied to products such as steel plates for the bodies of large mining dump trucks in extremely cold regions. DETAILED DESCRIPTION OF THE INVENTION

[0034] Example The weight percentages of the chemical compositions of the steel plates for the bodies of large mining dump trucks in arctic regions according to Examples 1 to 5 and Comparative Example 1 are shown in Table 1. The manufacturing methods for the steel plates for the bodies of large mining dump trucks in arctic regions according to Examples 1 to 5 and Comparative Example 1 all involved the sequential processes of smelting → casting → compounding → heating → rolling → online quenching → tempering using the appropriate smelting raw materials. The mass percentages of the chemical elements in the steel plates according to each Example were controlled, except that in the heating process, the slab heating temperature was 1050-1250°C and the temperature was maintained for 1-3 hours. The stacked continuously cast slabs were subjected to compound rolling, with the rolling start temperature being 950-1150°C, the rolling finish temperature being 880-980°C, and the reduction rate being ≥ 50%, followed by online quenching and water cooling from room temperature to 200°C. The tempering temperature was 150-350°C, and the temperature maintenance time (min) was 3*plate thickness. Specific process parameters for Examples 1 to 5 and Comparative Example 1 are shown in Table 2.

[0035] [Table 1]

[0036] [Table 2]

[0037] Mechanical Performance Test Mechanical performance tests were conducted on the multi-layer and base layer parts of the steel plates for the bodies of large mining dump trucks in extremely cold regions according to Examples 1 to 5 and the steel plate according to Comparative Example 1, where the hardness HBW was measured in accordance with GB / T 231.1-2018 Part 1 of the Brinell hardness test for metallic materials, and the -60°C Charpy V-notch longitudinal impact energy was measured in accordance with GB / T 12778-2008 Detection standard for the Charpy impact notch test method for metals, and the results are shown in Table 3.

[0038] [Table 3]

[0039] As can be seen from the above results, in the examples of the present invention, particularly in Examples 1 to 5 which further include specific production processes, the multi-layer steel plate portion has high hardness, and the base steel plate has high hardness while also having excellent low-temperature toughness. Therefore, in the steel plate for the body of a large mining truck for use in arctic regions, in which the multi-layer and base steel plates are metallurgically bonded, the toughness of the base steel plate portion is transmitted to the entire steel plate through the metallurgical bond, ensuring that the entire steel plate is resistant to fracture, while the high hardness of the composite portion prevents and reduces damage caused by minerals.

[0040] In summary, the steel plate for the bodies of large mining dump trucks in extremely cold regions according to the present invention is a steel plate that is excellent in hardness, toughness, welding performance, and mechanical processing performance by controlling the chemical composition of the multi-layer steel plate and base steel plate, the combined rolling process, and the heat treatment process, and can be applied to products such as steel plates for the bodies of large mining dump trucks in extremely cold regions.

Claims

1. It is divided into two layers, a multi-layer steel plate and a base steel plate, and the multi-layer steel plate and the base steel plate are metallurgically bonded; The chemical composition of the multilayer steel plate is C: 0.19 to 0.29 wt.%, Si: 0.15 to 0.75 wt.%, Mn: 0.55 to 1.55 wt.%, Cr: 0.10 to 0.70 wt.%, P: ≦0.030 wt.%, S: ≦0.010 wt.%, Al: 0.010 to 0.060 wt.%, B: 0.0005 to 0.0050 wt.%, and Mo: 0.01 to 0.60 wt.%, RE: 0.01 to 0.08 wt.%, Nb: 0.005 to 0.060 wt.%, V: 0.01 to 0.10 wt.%, Ti: 0.005 to 0.060 wt.%. %, the balance being Fe and unavoidable impurities; The chemical composition of the base steel plate is C: 0.08 to 0.13 wt.%, Si: 0.15 to 0.55 wt.%, Mn: 0.70 to 1.70 wt.%, Cr: 0.05 to 0.55 wt.%, Mo: 0.10 to 0.55 wt.%, Ni: 1.25 to 2.55 wt.%, P: ≦0.030 wt.%, S: ≦0.010 wt.%, Al: 0.010 to 0.080 wt.%, B: 0.0005 to 0.0050 wt.%, and RE: 0.01 to 0.08 wt.%, Nb: 0.005 to 0.060 wt.%, V: 0.01 to 0.10 wt.%. %, Ti: 0.005 to 0.060 wt. %, and the balance is Fe and unavoidable impurities. A steel plate for the body of a dump truck for use in large mines in extremely cold regions.

2. It is divided into two layers, a multi-layer steel plate and a base steel plate, and the multi-layer steel plate and the base steel plate are metallurgically bonded; The multi-layer steel plate contains, in addition to Fe and other unavoidable impurities, C: 0.19 to 0.29 wt.%, Si: 0.15 to 0.75 wt.%, Mn: 0.55 to 1.55 wt.%, Cr: 0.10 to 0.70 wt.%, P: ≦0.030 wt.%, S: ≦0.010 wt.%, Al: 0.010 to 0.060 wt.%, B: 0.0005 to 0.0050 wt.%, Mo: 0.01 to 0.60 wt.%, RE: 0.01 to 0.08 wt.%, Nb: 0.005 to 0.060 wt.%, V: 0.01 to 0.10 wt.%, Ti: 0.005 to 0.060 wt.%, and the like. %; In addition to Fe and other unavoidable impurities, the base steel plate contains C: 0.08 to 0.13 wt.%, Si: 0.15 to 0.55 wt.%, Mn: 0.70 to 1.70 wt.%, Cr: 0.05 to 0.55 wt.%, Mo: 0.10 to 0.55 wt.%, Ni: 1.25 to 2.55 wt.%, P: ≦0.030 wt.%, S: ≦0.010 wt.%, Al: 0.010 to 0.080 wt.%, B: 0.0005 to 0.0050 wt.%, and RE: 0.01 to 0.08 wt.%, Nb: 0.005 to 0.060 wt.%, V: 0.01 to 0.10 wt.%. %, and Ti: 0.005 to 0.060 wt. %. A steel plate for the body of a dump truck for use in large mines in extremely cold regions.

3. The multilayer steel plate contains Mo: ≦0.20 wt. %, RE: ≦0.05 wt. %, Nb: 0.010 to 0.030 wt. %, V≦0.06 wt. %, and Ti: 0.010 to 0.030 wt. %; The base layer steel plate contains RE: ≦0.06 wt. %, Nb: 0.010 to 0.030 wt. %, V: ≦0.08 wt. %, and Ti: 0.01 to 0.035 wt. %.

3. The steel plate for a body of a dump truck for use in a large mine in an extremely cold region according to claim 1 or 2.

4. 3. The steel plate for the body of a dump truck for large mines in extremely cold regions according to claim 1 or 2, characterized in that the carbon equivalent Ceq of the multilayer steel plate is 0.40 to 0.50, and the carbon equivalent Ceq of the base layer is 0.45 to 0.60; with the proviso that carbon equivalent Ceq = C + Mn / 6 + (Cr + Mo + V) / 5 + (Cu + Ni) / 15.

5. The steel plate for the body of a dump truck for large mining use in extremely cold regions according to any one of claims 1 to 4, characterized in that the multilayer steel plate and the base steel plate are metallurgically bonded by a rolling process.

6. 5. The steel plate for the body of a dump truck for use in a large mining operation in an extremely cold region according to claim 1, wherein the mechanical properties of the multi-layer steel plate are a Brinell hardness of 450 HBW or more and a -60°C Charpy V-notch longitudinal impact energy of 10 J or more, and the mechanical properties of the base layer steel plate are a Brinell hardness of 300 HBW or more and a -60°C Charpy V-notch longitudinal impact energy of 100 J or more.

7. The microstructure of the multilayer steel plate is martensite and retained austenite, and the microstructure of the base steel plate is martensite and / or bainite, and retained austenite. Steel plate for the body of a dump truck for large mining in extremely cold regions according to any one of claims 1 to 4.

8. The thickness of the multilayer steel plate is 5 to 20 mm, and the thickness of the base layer steel plate is 6 to 15 mm. Steel plate for the body of a dump truck for large mining in extreme cold regions according to any one of claims 1 to 4.

9. A method for manufacturing a steel plate for the body of a dump truck for use in a large mine in an extremely cold region, comprising the following steps: (1) forming a multi-layer continuous casting billet and a base layer continuous casting billet through smelting and casting; (2) forming a composite stacked billet from the multi-layer continuous casting billet and the base layer continuous casting billet; (3) Slab heating and slab rolling of the composite stacked billet: In the heating process, the slab heating temperature is 1100-1250°C and is kept at that temperature for 1-3 hours; the stacked continuous cast slabs are rolled, with the rolling start temperature being 1000-1150°C and the rolling end temperature being 880-980°C, and the reduction rate being ≥ 50%. After rolling, the slabs are quenched online at room temperature to 200°C.

10. 10. The method of claim 9, wherein the step of forming a composite stacked billet from the multi-layer continuous cast billet and the base layer continuous cast billet comprises the steps of: (i) Using a mechanical method, the surface oxide layer on one side of the surfaces to be bonded of the multi-layer continuous casting billet and the base layer continuous casting billet is cleaned, and the four sides of the surface from which the surface oxide layer has been cleaned are beveled; (ii) The multilayer continuous casting billet and the base layer continuous casting billet, the surfaces of which have been cleaned, are left to stand and bonded together so that the cleaned surface of the multilayer continuous casting billet faces the cleaned surface of the base layer continuous casting billet; (iii) The bonding surfaces of the multi-layer continuous casting billet and the base layer continuous casting billet are welded and sealed in four directions, leaving vacuum channels at the edges, and the welded and sealed composite stacked billet is subjected to a vacuum process through the vacuum channels, and then sealed to form a composite stacked billet.

11. The manufacturing method according to claim 9 or 10, characterized in that tempering heat treatment is performed after slab rolling; the tempering temperature is 150 to 350°C, and the heat retention time is 3 x plate thickness min, and the plate thickness is expressed in mm.

12. The manufacturing method described in claim 9 or 10, characterized in that the multi-layer continuous casting billet has the chemical composition of the multi-layer steel plate described in claim 1 or 2, and the base layer continuous casting billet has the chemical composition of the base layer steel plate described in claim 1 or 2.

13. The manufacturing method according to claim 9 or 10, characterized in that in the rolled steel plate, the mechanical properties of the multi-layer steel plate are a Brinell hardness of 450HBW or more and a -60°C Charpy V-notch longitudinal impact energy of 10J or more, and the mechanical properties of the base steel plate are a Brinell hardness of 300HBW or more and a -60°C Charpy V-notch longitudinal impact energy of 100J or more.

14. The manufacturing method according to claim 9 or 10, wherein in the rolled steel plate, the thickness of the multi-layer steel plate is 5 to 20 mm, and the thickness of the base steel plate is 6 to 15 mm.

Images