Steel plate for a large mine dump truck body in an extremely cold region and a manufacturing method thereof

Abstract

The present application relates to a kind of steel plate for large mining dump truck box in polar region and its manufacturing method, it is characterized in that, the steel plate is divided into two layers of complex layer steel plate and base layer steel plate, the complex layer steel plate and the base layer steel plate are metallurgical combination, the chemical composition of the complex layer steel plate is: C;Si;Mn;Cr;P;S;Al;B, and one or several selected from Mo;RE;Nb;V;Ti, the balance is Fe and inevitable impurity;The chemical composition of the base layer plate is: C;Si;Mn;Cr;Mo;Ni;P;S;Al;B, and one or several selected from RE;Nb;V;Ti, the balance is Fe and inevitable impurity.

Description

TECHNICAL FIELD

[0001] The present application relates to a steel plate for a large mine dump truck body in extremely cold regions and a manufacturing method thereof. BACKGROUND

[0002] The wear-resistant steel plate is generally used in engineering, mining, cement production, port, power and metallurgical mechanical equipment, such as scraper conveyor and dump truck body, under particularly harsh working conditions, requiring high wear resistance, high strength, high hardness, high toughness.

[0003] In particular, the large mine dump truck serving in extremely cold regions such as Canada and Russia in North America has high requirements on the comprehensive performance of the vehicle body material, especially the low-temperature performance, due to the low temperature of the working environment. Compared with ordinary high-strength steel, the low-alloy high-strength wear-resistant steel plate for the dump truck body has higher strength, but poorer low-temperature toughness. At an extremely cold ambient temperature of below-40℃ or even-60℃, the body steel plate, especially the bottom plate, is often easily broken by the impact of ore. In addition, due to the large size of the wear-resistant steel plate for the body, it is not easy to preheat for welding, so the steel plate needs to have good weldability. It still needs further research to simultaneously meet the requirements of high wear resistance, high strength, high hardness, high toughness and weldability of the body of the large mine dump truck in extremely cold regions. SUMMARY

[0004] The present application aims to solve the above-mentioned problems and provide a steel plate for a large mine dump truck body in extremely cold regions and a manufacturing method thereof.

[0005] To achieve the above-mentioned application purposes, the present application provides a steel plate for a large mine dump truck body in extremely cold regions. The steel plate is divided into two layers of a clad layer and a base layer, and the two layers are combined by metallurgy. Specifically, the chemical composition of the clad layer steel plate is:

[0006] C: 0.19-0.29wt.%;

[0007] Si: 0.15-0.75wt.%;

[0008] Mn: 0.55-1.55wt.%;

[0009] Cr: 0.10-0.70wt.%;

[0010] P: ≤0.030wt.%;

[0011] S: ≤0.010wt.%;

[0012] Al: 0.010-0.060wt.%;

[0013] B: 0.0005-0.0050wt.%

[0014] and

[0015] Mo: 0.01 - 0.60 wt.%;

[0016] RE: 0.01 - 0.08 wt.%;

[0017] Nb: 0.005 - 0.060 wt.%;

[0018] V: 0.01 - 0.10 wt.%;

[0019] Ti: 0.005 - 0.060 wt.%;

[0020] one or several of the above, the remainder being Fe and unavoidable impurities.

[0021] The base sheet has the following chemical composition:

[0022] C: 0.08 - 0.13 wt.%;

[0023] Si: 0.15 - 0.55 wt.%;

[0024] Mn: 0.70 - 1.70 wt.%;

[0025] Cr: 0.05 - 0.55 wt.%;

[0026] Mo: 0.10 - 0.55 wt.%;

[0027] Ni: 1.25 - 2.55 wt.%;

[0028] P: < 0.030 wt.%;

[0029] S: < 0.010 wt.%;

[0030] Al: 0.010 - 0.080 wt.%;

[0031] B: 0.0005 - 0.0050 wt.%

[0032] and

[0033] RE: 0.01 - 0.08 wt.%;

[0034] Nb: 0.005 - 0.060 wt.%;

[0035] V: 0.01 - 0.10 wt.%;

[0036] Ti: 0.005 - 0.060 wt.%;

[0037] one or several of the above, the remainder being Fe and unavoidable impurities.

[0038] Thus, by the above steel element composition design, the clad steel plate has high strength and hardness, and the base steel plate has excellent low-temperature toughness while having high strength and hardness. The steel plate compounded by the rolling process is metallurgically combined between the layers of steel plates, which can ensure the integrity of the steel plate and can also play the characteristics of each layer of steel plate, so that the composite plate as a whole has excellent comprehensive mechanical properties. In addition, by controlling the content of carbon and alloying elements, and further reducing the carbon equivalent, the steel plate has excellent welding performance.

[0039] Specifically, the composition design principle of the steel plate for the box body of the large mining dump truck in the extremely cold zone is:

[0040] Carbon: Carbon is the most basic and important element in wear-resistant steel, which improves the strength and hardness of the steel through solid solution strengthening and precipitation strengthening, and is also an important element for obtaining martensite structure. If the carbon content is too low, it cannot guarantee that the steel obtains bainite or martensite structure and the required mechanical properties and wear resistance; if the carbon content is too high, it will increase the segregation tendency of the steel during continuous casting or mold casting, resulting in serious segregation of the steel plate, reducing the toughness of the steel plate, and the mechanical properties do not meet the requirements. In the clad steel plate of the present application, the carbon content is controlled to be 0.19-0.29wt.%, preferably 0.20-0.29wt.%, to ensure the strength and hardness of the steel plate; the carbon content in the base steel plate is controlled to be 0.08-0.13wt.%, preferably 0.08-0.12wt.%, to ensure the strength and hardness of the steel plate while considering the toughness.

[0041] Silicon: Appropriate silicon is a beneficial deoxidizer in steel, which can form calcium-aluminum silicate inclusions with calcium and aluminum in steel, which can improve the purity of the steel. Silicon solid solution in ferrite and austenite can improve their hardness and strength, but too high silicon content will cause the toughness of the steel to decrease sharply. Therefore, in the clad steel plate of the present application, the Si content is controlled to be 0.15-0.75wt.%, preferably 0.20-0.75wt.%; in the base steel plate, the Si content is controlled to be 0.05-0.55wt.%, preferably 0.10-0.50wt.%.

[0042] Manganese: Manganese strongly increases the hardenability of the steel, reduces the transformation temperature of the steel and the critical cooling speed of the steel. However, when the manganese content is high, it has a tendency to coarsen the grains and increase the temper brittleness sensitivity of the steel, and it is easy to cause segregation and cracks in the billet, reducing the performance of the steel plate. Therefore, in the clad steel plate of the present application, the Mn content is controlled to be 0.55-1.55wt.%, preferably 0.60-1.50wt.%; in the base steel plate, the Mn content is controlled to be 0.70-1.70wt.%, preferably 0.70-1.60wt.%.

[0043] Chromium: Chromium can improve the hardenability of steel and increase the strength and hardness of steel. Chromium can prevent or slow down the precipitation and aggregation of carbides when tempered, which can improve the tempering stability of steel. Chromium can significantly improve corrosion resistance. Therefore, the Cr content in the clad steel plate of the present application is controlled to be 0.05-0.55wt.%, preferably 0.10-0.55wt.%; the Cr content in the base steel plate is controlled to be 0.15-0.55wt.%, preferably 0.15-0.50wt.%.

[0044] Aluminum: Aluminum and nitrogen in steel can form fine and insoluble AlN particles, which can refine the grain of steel. Aluminum can refine the grain of steel, fix nitrogen and oxygen in steel, reduce the sensitivity of steel to notches, reduce or eliminate the aging phenomenon of steel, and improve the toughness of steel. Therefore, the Al content in the clad steel plate of the present application is controlled to be 0.010-0.060wt.%, preferably 0.015-0060wt.%; the Al content in the base steel plate is controlled to be 0.010-0.080wt.%, preferably 0.010-0.070wt.%.

[0045] Boron: Adding a small amount of boron to steel can greatly improve the quenching hardenability, but too much boron can easily enrich at the grain boundary, reduce the grain boundary binding energy, and make the steel plate more prone to fracture along the grain boundary under impact load, reducing the low temperature impact absorption energy of the steel plate. Therefore, the B content in the clad steel plate of the present application is controlled to be B: 0.0005-0.0050wt.%, preferably 0.0010-0.0050wt.%; the B content in the base steel plate of the present application is controlled to be B: 0.0005-0.0050wt.%, preferably 0.0005-0.0040wt.%.

[0046] Among other elements, molybdenum: molybdenum can refine the grain, improve the strength and toughness. Molybdenum is an element that can reduce the temper brittleness, and can improve the temper stability. RE: RE represents rare earth elements, specifically selected from one or more of La, Ce, Nd, adding rare earth in the steel can reduce the segregation of sulfur, phosphorus and other elements, improve the shape, size and distribution of non-metallic inclusions, while can refine the grain, strengthen the grain boundary, improve the hardness and toughness. Nickel: nickel has a significant effect on reducing the cold brittle transition temperature, but too high content can lead to the steel plate surface oxide scale difficult to fall off, and the cost increases significantly. Niobium: niobium improves the strength and toughness of the steel through grain refinement. Titanium: titanium is one of the strong carbide forming elements, which forms fine TiC particles. TiC particles are small and distributed in the grain boundary, achieving the effect of grain refinement. The hard TiC particles improve the wear resistance of the steel. Therefore, the multilayer steel plate of the present application contains one or more of 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.%. The base steel plate contains one or more of Re: 0.01-0.08wt.%; Nb: 0.005-0.060wt.%; V: 0.01-0.10wt.%; Ti: 0.005-0.060wt.%.

[0047] Phosphorus and sulfur: in wear-resistant steel, both sulfur and phosphorus are harmful elements, and their content must be strictly controlled. The phosphorus content in the steel of the present application is controlled to be ≤0.030wt.%; and the sulfur content is controlled to be ≤0.010wt.%.

[0048] In one embodiment of the present application, the steel plate for the body of large mining dump truck in extremely cold regions is composed of the above-mentioned elements, Fe and unavoidable impurities. In another embodiment of the present application, the steel plate for the body of large mining dump truck in extremely cold regions contains the above-mentioned elements, Fe and unavoidable impurities.

[0049] Preferably, the steel plate for the body of large mining dump truck in extremely cold regions is a composite steel plate, and the typical mechanical properties are as follows: the typical mechanical properties of the multilayer steel plate are Brinell hardness of 450HBW or more, impact energy of-60℃ of 10J or more, preferably 15J or more, and more preferably 20J or more; the typical mechanical properties of the base steel plate are Brinell hardness of 300HB or more, impact energy of-60℃ of 100J or more, preferably 115J or more, and preferably 120J or more. The microstructure of the multilayer steel plate is martensite and a small amount of residual austenite, and the microstructure of the base steel plate is martensite or bainite and residual austenite.

[0050] In the steel plate for the large mine dump truck body in the extremely cold zone, the metallurgical bond between the clad steel plate and the base steel plate refers to the bond formed by the mutual diffusion of atoms between the interface of the base and the clad, which can be realized by the common metallurgical bonding means, such as the explosive compounding process, the rolling compounding process, and preferably the rolling compounding process.

[0051] In the steel plate for the large mine dump truck body in the extremely cold zone, the thickness specification ratio of the base and the clad is determined according to the product performance requirement, in one embodiment, the thickness of the clad steel plate is 5-20 mm, and more preferably 6-18 mm, and the thickness of the base steel plate is 6-15 mm, and more preferably 8-14 mm.

[0052] The steel plate for the large mine dump truck body in the extremely cold zone is obtained by controlling the chemical composition of the clad and the base steel plate, the rolling compounding process and the heat treatment process, and has excellent strength, toughness, welding performance and machining performance, and is suitable for the steel plate for the large mine dump truck body in the extremely cold zone and other products.

[0053] The manufacturing method of the steel plate for the large mine dump truck body in the extremely cold zone comprises the following steps:

[0054] (1) smelting and casting to form a clad continuous casting billet and a base continuous casting billet;

[0055] (2) forming a composite group billet from the clad continuous casting billet and the base continuous casting billet;

[0056] (3) slab heating and slab rolling of the composite group billet: in the heating step, the slab heating temperature is 1100-1250℃, and the holding time is 1-3 hours. The combined continuous casting slab is rolled, wherein the opening rolling temperature is 1000-1150℃, the final rolling temperature is 880-980℃, and the reduction is ≥50%. After rolling, it is quenched to room temperature-200℃ online, and according to the need, it can be subjected to tempering heat treatment; the tempering temperature is 150-350℃, and the holding time is 3×plate thickness min, the plate thickness unit is mm.

[0057] Preferably, the process of forming a composite group billet from the clad continuous casting billet and the base continuous casting billet comprises the following steps:

[0058] (i) using a mechanical method to clean the single surface oxide layer of the to-be-pasted surface of the clad continuous casting billet and the base continuous casting billet, and then performing beveling on the four edges of the surface after cleaning the surface oxide layer;

[0059] (ii) placing and pasting the cleaned clad continuous casting billet and the base continuous casting billet with the cleaned surface of the clad continuous casting billet against the cleaned surface of the base continuous casting billet;

[0060] (iii) welding and sealing the joint surface of the clad continuous casting billet and the base continuous casting billet all around and leaving a vacuum passage at the edge, and then performing vacuum extraction treatment on the clad assembly billet after the welding and sealing, and then sealing to form the clad assembly billet.

[0061] In the manufacturing method of the steel plate for the large mine dump truck body in the extremely cold zone, the thickness specification ratio of the base layer and the clad layer continuous casting billet is determined according to the performance requirement of the product.

[0062] Compared with the prior art, the steel plate for the large mine dump truck body in the extremely cold zone has the following beneficial effects:

[0063] 1. From the chemical composition, the clad steel plate of the steel plate is mainly composed of medium-high carbon low alloy, fully utilizing the hardening effect of C and a small amount of alloy elements, improving the strength of the steel plate, and at the same time, improving the welding performance of the steel plate as much as possible; the chemical composition of the base steel plate is mainly composed of low carbon low alloy, by adding appropriate amount of Mo, Ni, Nb, V, Ti and other alloy elements, improving the impact toughness of the steel plate, and at the same time, improving the weldability of the steel plate as much as possible. Through the different chemical composition ratio of the base layer and the clad layer steel plate, the steel plate has excellent strength and toughness, easy weldability, easy machinability and wear resistance, etc.

[0064] 2. From the production process, two continuous casting billets are used to form a clad assembly. By controlling the heating temperature, the starting and finishing rolling temperature, the rolling deformation, the on-line quenching temperature and the tempering temperature, the microstructure is refined and the strengthening effect is improved, thereby reducing the content of carbon and alloy elements, and obtaining a steel plate with excellent mechanical properties and wear resistance. At the same time, the metallurgical combination of the base layer and the clad layer steel plate ensures the performance of the steel plate product.

[0065] 3. From the product performance, the steel plate for the large mine dump truck body in the extremely cold zone has excellent strength and toughness: the typical mechanical properties of the clad steel plate are: impact energy at-60℃ of 10J or more, preferably 15J or more, and more preferably 20J or more; the typical mechanical properties of the base steel plate are: Brinell hardness of 300HB or more, impact energy at-60℃ of 100J or more, preferably 115J or more, and more preferably 120J or more. In the steel plate for the large mine dump truck body in the extremely cold zone formed by the metallurgical combination of the clad layer and the base layer, the toughness of the base layer can be transmitted to the whole steel plate through the metallurgical combination, ensuring that the whole steel plate is not easy to break, and at the same time, the high hardness of the clad steel plate reduces the damage caused by minerals.

[0066] 4. From the microstructure, the steel plate for the large mine dump truck body in the extremely cold zone has the following microstructure: the clad steel plate has martensite and a small amount of residual austenite, and the base steel plate has martensite or bainite and residual austenite.

[0067] In summary, the present application relates to the steel plate for large mine dump truck body in extremely cold zone, which is obtained by controlling the chemical composition of the base layer and the clad layer, the rolling composite process and the heat treatment process, and has excellent strength, toughness, welding performance and machining performance, and is suitable for the steel plate for large mine dump truck body in extremely cold zone and other products. Examples

[0068] The steel plates for large mine dump truck body in extremely cold zone of Examples 1-3 have the chemical composition as shown in Table 1. The manufacturing method of the steel plates for large mine dump truck body in extremely cold zone of Examples 1-3 is as follows: smelting, casting, compounding, heating, rolling, on-line quenching and tempering. The mass percentage of each chemical element in the steel plate of each example is controlled, and in the heating step, the slab heating temperature is 1050-1250℃, and the holding time is 1-3 hours. The combined continuous casting slab is subjected to composite rolling, and the opening rolling temperature is 950-1150℃, the final rolling temperature is 880-980℃, the reduction is ≥50%, the on-line quenching is water cooled to room temperature-200℃, the tempering temperature is 150-350℃, and the holding time is 3*plate thickness min. The specific process parameters of Examples 1-3 are shown in Table 2.

[0069]

[0070]

[0071] Mechanical property test

[0072] The mechanical properties of the steel plates for large mine dump truck body in extremely cold zone of Examples 1-3 were tested, in which the hardness HBW was determined according to GB / T 231.1-2018, and the -60℃ Charpy V-type longitudinal impact energy was determined according to GB / T 12778-2008, and the results are shown in Table 3.

[0073] Table 3 Mechanical properties of Examples 1-3

[0074]

[0075] Note: The impact energy value in Table 3 is the impact energy value of the 10mm standard sample after proportional reduction.

[0076] The above results show that in the embodiments of the present application, especially embodiments 1-3 further having a specific production process, the clad steel plate has high strength and hardness, and the base steel plate has high strength and hardness and excellent low-temperature toughness performance. Therefore, in the steel plate for a large mining dump truck body in an extremely cold zone, which has the above-mentioned clad layer and base layer metallurgical bonding, the toughness of the base layer can be transmitted to the whole steel plate through the metallurgical bonding, ensuring that the whole steel plate is not easy to break, and the high hardness of the clad steel plate reduces and avoids damage caused by minerals.

[0077] In summary, the steel plate for a large mining dump truck body in an extremely cold zone of the present application has high strength and hardness, toughness, and excellent welding and machining performance by controlling the chemical composition of the clad layer and the base layer steel plate, the rolling composite process, and the heat treatment process, and is suitable for steel plate products for a large mining dump truck body in an extremely cold zone and the like.

Claims

1. A steel plate for the body of a large mining dump truck used in extremely cold regions, characterized in that, The steel plate consists of two layers: a cladding steel plate and a base steel plate. The cladding steel plate and the base steel plate are metallurgically bonded. The thickness of the cladding steel plate is 5–18 mm, and the thickness of the base steel plate is 6–15 mm. The chemical composition of the cladding steel plate is: C: 0.19–0.29 wt.%; Si: 0.15–0.75 wt.%; Mn: 0.55–1.55 wt.%; Cr: 0.10–0.55 wt.%; P: ≤0.030 wt.%. S: ≤0.010wt.%; Al: 0.010-0.060 wt.%; B: 0.0005-0.0050 wt.%, and one or more selected from Mo: 0.01-0.60 wt.%; RE: 0.01-0.08 wt.%; Nb: 0.005-0.060 wt.%; V: 0.01-0.10 wt.%; Ti: 0.005-0.060 wt.%, with the balance being Fe and unavoidable impurities; The chemical composition of the base steel plate is as follows: 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.%; S: ≤0.010 wt.%; Al: 0.010-0.080 wt.%; B: 0.0005-0.0050 wt.%; and one or more selected from RE: 0.01-0.08 wt.%; Nb: 0.005-0.060 wt.%; V: 0.01-0.10 wt.%; Ti: 0.005-0.060 wt.%, with the balance being Fe and unavoidable impurities. The microstructure of the cladding steel plate is martensite and retained austenite, and the microstructure of the base steel plate is martensite and / or bainite, and retained austenite.

2. The steel plate for the body of a large mining dump truck in extremely cold regions according to claim 1, wherein the cladding steel plate and the base steel plate are metallurgically bonded by a rolling process.

3. The steel plate for the body of a large mining dump truck in extremely cold regions according to claim 1 or 2, wherein the mechanical properties of the cladding steel plate are a Brinell hardness of 450 HBW or higher and an impact energy of 10 J or higher in a Charpy V-shaped longitudinal impact at -60℃, and the mechanical properties of the base steel plate are a Brinell hardness of 300 HBW or higher and an impact energy of 100 J or higher in a Charpy V-shaped longitudinal impact at -60℃.

4. The steel plate for the body of a large mining dump truck in extremely cold regions according to claim 1 or 2, wherein the thickness of the cladding steel plate is 5-15mm and the thickness of the base steel plate is 10-15mm.

5. A method for manufacturing steel plates for the body of a large mining dump truck in extremely cold regions, as described in any one of claims 1 to 4, characterized in that, The method for manufacturing the steel plate involves sequentially performing the following steps: smelting → casting → compounding → heating → rolling → online quenching → tempering, including: (1) Smelting and casting form multi-layer continuous casting billets and base continuous casting billets; (2) Form a composite billet by combining the multi-layer continuous casting billet and the base continuous casting billet; (3) Heating and rolling of the composite billet: In the heating step, the billet heating temperature is 1100~1250℃, and the temperature is held for 1~3 hours. The assembled continuous casting billet is rolled, with the initial rolling temperature being 1000~1150℃, the final rolling temperature being 880~980℃, and the reduction rate being ≥50%. After rolling, the billet is quenched online to between room temperature and 200℃.

6. The manufacturing method according to claim 5, wherein the step of forming a composite billet from the stratified continuous casting billet and the base continuous casting billet includes: (i) The surface oxide layer of the composite continuous casting billet and the base continuous casting billet to be bonded is cleaned on one side by mechanical method, and then the four edges of the surface after the surface oxide layer is cleaned are beveled. (ii) Place the cleaned cladding billet and the base continuous casting billet together with the cleaned surface of the cladding billet facing the cleaned surface of the base continuous casting billet. (iii) Weld and seal the four sides of the mating surfaces of the compositing and base continuous casting billets, while leaving a vacuum channel at the edge. Through the vacuum channel, vacuum treatment is performed on the welded and sealed composite billet, and then it is sealed to form a composite billet.

7. The manufacturing method according to claim 5 or 6, wherein a tempering heat treatment is performed after the slab is rolled; the tempering temperature is 150-350℃, and the holding time is 3 × slab thickness min, where the slab thickness is in mm.

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