High-wear-resistance steel as well as preparation method and application thereof

Abstract

The invention discloses high-wear-resistance steel as well as a preparation method and application thereof, and relates to the field of wear-resistant materials. The high-wear-resistance steel provided by the invention comprises the following components in percentage by weight: 0.16 to 0.19 percent of C, 1.1 to 1.3 percent of Mn, 0.08 to 0.20 percent of Si, 0.15 to 0.25 percent of Cr, 0.01 to 0.03 percent of Ti, 0.0012 to 0.0020 percent of B, less than or equal to 0.006 percent of N, 0.02 to 0.05 percent of RE and the balance of Fe and inevitable trace elements. Wherein Cr7C3 formed by the Cr element can improve the strength of the steel, and introduction of Ti (C, N) and RE elements formed by the Ti element can improve the toughness of the steel, so that the steel provided by the invention has excellent wear resistance, and the wear resistance is improved by more than two times compared with the traditional Q355 steel.

Description

Technical Field

[0001] The present invention relates to the field of wear-resistant materials, and in particular to a highly wear-resistant steel material and a preparation method and application thereof. Background Art

[0002] With the rapid development of the global power industry, the coverage of the power grid continues to expand. As the "link" in the power grid architecture, the importance of power connection hardware is increasingly highlighted. The hanging plate is an important accessory in the power connection hardware. In high-voltage, ultra-high-voltage and ultra-high-voltage power transmission systems, the hanging plate will be the core component of the connection hardware, directly involved in the transmission and distribution of electric energy, and its performance is directly related to the safe operation of the power grid and the reliability of power supply.

[0003] However, the working environment of the hanging board is quite harsh. In the actual working process, the hanging board not only needs to withstand huge mechanical stress, but also often faces strong winds, high temperatures, humidity and extreme temperature differences. Traditional power connection hardware hanging board materials, such as aluminum alloys and ordinary steel (generally low-alloy high-strength steel, including Q420, Q355 steel, etc.), although they have high strength and corrosion resistance, their wear resistance during long-term outdoor operations is still insufficient. According to statistics, in areas with strong winds and sand, the average replacement cycle of traditional hanging boards is only 5 to 7 years, which not only increases maintenance costs, but also affects the stability of the power grid and the continuity of power supply. By improving the wear resistance of the hanging board material, the service life of the hanging board can be increased, but while improving the wear resistance, it is also necessary to avoid affecting the strength of the hanging board material. Therefore, how to prepare a hanging board material with both high strength and high wear resistance has become a problem that needs to be solved urgently.

[0004] Chinese patent CN 103014501 A discloses a rare earth treated high strength impact resistant steel for wind power. The steel is chemically designed and treated with rare earth. The Nb, Ti, V and other elements in the steel improve the strength and plasticity of the steel through fine grain strengthening. The spherical composite inclusions formed by the rare earth elements improve the impact toughness of the steel. However, the maximum yield strength of the steel is only 480MPa, and the maximum tensile strength is 600MPa. At the same time, the prior art does not pay attention to the wear resistance of the steel. Summary of the invention

[0005] In order to solve the problem that the prior art cannot provide a steel with high mechanical properties and thus high wear resistance, the present invention provides a high wear-resistant steel, into which Cr, Ti and RE elements are added, wherein the Cr element can form a Cr7C3 hard phase to improve the strength of the steel, the Ti element forms a Ti(C, N) dispersed phase and the RE element provides a fine grain strengthening effect, and the above three elements respectively improve the strength and toughness of the steel, thereby making the steel provided by the present invention have excellent wear resistance.

[0006] Another object of the present invention is to provide a method for preparing high wear-resistant steel.

[0007] Another object of the present invention is to provide the use of the above-mentioned high wear-resistant steel in the preparation of electric power fittings.

[0008] Another object of the present invention is to provide an electric power fitting hanging plate made of the above-mentioned high wear-resistant steel.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] A high wear-resistant steel material comprising the following chemical components calculated by mass percentage:

[0011] C: 0.16~0.19Wt%, Mn: 1.1~1.3Wt%, Si: 0.08~0.20Wt%, Cr: 0.15~0.25Wt%, Ti: 0.01~0.03Wt%, B: 0.0012~0.0020Wt%, N: ≤0.006Wt%, RE: 0.02~0.05Wt%, the remainder is Fe and inevitable trace elements.

[0012] In the high wear-resistant steel provided by the present invention, a small amount of Cr and Ti elements are added to the alloy composition, wherein the Cr element has a strong affinity with C, and Cr and C will combine to form a Cr7C3 hard phase, whose hardness is as high as HV1400-1800, significantly improving the strength of the steel; the Ti element will combine with C and N to form fine dispersed Ti (C, N), refine the grains, and then promote the formation of ferrite, thereby improving the toughness of the steel; the addition of trace RE (rare earth) elements can also refine the grains of the steel, improve its organizational structure, and thus significantly improve the mechanical strength and toughness of the steel, making it more adaptable to complex working environments. The present invention greatly improves the wear resistance of the steel by improving the mechanical strength and toughness, so that the steel can have a longer service life in outdoor working environments.

[0013] It should be noted that the content of Cr in the steel should not exceed 0.25Wt%, because too much Cr7C3 hard phase will affect the toughness of the steel; the content of Ti should not exceed 0.03Wt%, otherwise Ti (C, N) formed by Ti, C and N will aggregate and coarsen, and cannot play a role in fine grain strengthening, affecting the toughness and strength of the steel; the content of RE should not exceed 0.05Wt%, nor should it be less than 0.02Wt%, because it is necessary to ensure that the steel has sufficient elongation at break while having strength and toughness. If the content of Cr and Ti is too little, the two elements will not play a corresponding role in the steel. As for the content of C, Mn, Si and other elements in the present invention, they belong to the conventional content in low-alloy high-strength steel, and must be contained in order to ensure that the steel has a certain strength and toughness. In addition, the steel provided by the present invention also contains N element with a mass percentage not higher than 0.006, which is a common impurity in steel. It is mainly introduced due to the molten steel absorbing and dissolving nitrogen in the furnace gas during smelting. Improper control of converter reblowing and untimely switching of nitrogen and argon will also increase the nitrogen content; nitrogen in molten steel raw materials such as ferroalloys, scrap steel and slag will also be brought into the molten steel along with the furnace charge.

[0014] Preferably, the above-mentioned high wear-resistant steel comprises the following chemical components calculated by mass percentage:

[0015] C: 0.17~0.18Wt%, Mn: 1.15~1.23Wt%, Si: 0.11~0.19Wt%, Cr: 0.17~0.24Wt%, Ti: 0.01~0.02Wt%, B: 0.0013~0.0018Wt%, N: ≤0.006Wt%, RE: 0.03~0.04Wt%, the balance is Fe and inevitable trace elements.

[0016] Preferably, the mass ratio of Cr to Ti and RE in the chemical composition of the steel is Cr:(Ti+RE)=(4.5-5):1.

[0017] More preferably, the mass ratio of Cr to Ti in the chemical composition of the steel material is Cr:Ti=(23-24):1.

[0018] In the high wear-resistant steel provided by the present invention, the Cr element can improve the strength of the steel, but too high a content thereof will affect the toughness of the steel; the introduction of Ti and RE elements can improve the toughness of the steel, but too high a content thereof will affect the strength and elongation at break of the steel. When the mass ratio of Cr to Ti and RE is Cr:(Ti+RE)=(4.5-5):1, especially when the mass ratio of Cr to Ti satisfies Cr:Ti=(23-24):1, the obtained steel has excellent strength, toughness and elongation at break, and excellent wear resistance.

[0019] More preferably, the above-mentioned high wear-resistant steel comprises the following chemical components calculated by mass percentage:

[0020] C: 0.18Wt%, Mn: 1.15Wt%, Si: 0.12Wt%, Cr: 0.24Wt%, Ti: 0.01Wt%, B: 0.0014Wt%, N: ≤0.006Wt%, RE: 0.04Wt%, and the balance is Fe and inevitable trace elements.

[0021] The present invention also protects a method for preparing the above-mentioned high wear-resistant steel, comprising the following steps:

[0022] S1. Converter smelting: Molten steel is obtained by smelting molten iron and scrap steel. The molten iron entering the furnace requires S≤0.035Wt%; the converter tapping end point requires C≥0.15Wt%, P≤0.020Wt%, and ferrosilicon, ferromanganese and ferrochrome are added as needed during tapping;

[0023] S2.LF refining, during the refining process after the molten steel enters the LF furnace, titanium iron, boron iron and rare earth alloy are added as needed;

[0024] S3.RH refining;

[0025] S4. Continuous casting, the continuous casting process adopts full-process protective pouring.

[0026] The preparation method provided by the present invention follows the conventional converter (BOF)-ladle refining (LF)-vacuum cycle degassing refining (RH)-continuous casting (CC) double process route, wherein ferrosilicon, ferromanganese and ferrochrome are added as needed in the converter smelting step of step S1 according to the conventional method; the purpose of the LF refining process in step S2 is mainly to deoxidize the molten steel and remove the inclusions therein, fine-tune the chemical composition of the molten steel (therefore, ferrotitanium and rare earth alloy are added as needed in step S2), and adjust the temperature of the molten steel to ensure the chemical composition and quality of the molten steel, and provide guarantee for stable casting in the continuous casting process; in step S4, the continuous casting process adopts full-process protective casting, that is, a protective sleeve is used for protective casting from the ladle to the tundish, the molten steel liquid surface of the tundish is covered with a tundish covering agent, and an immersion nozzle is used for protective casting from the tundish to the crystallizer, and a low-alloy steel crystallizer protective slag is added to the molten steel liquid surface of the crystallizer, so as to insulate the molten steel and prevent the molten steel from secondary oxidation.

[0027] It should be noted that in the preparation method provided by the present invention, the molten steel can be denitrified by passing through the RH furnace, so the N content of the steel can be controlled below 0.006Wt%.

[0028] It should be noted that step S1 requires that the molten iron S≤0.035Wt%, the converter tapping end point C≥0.15Wt%, and P≤0.020Wt%, in order to ensure the cleanliness of the molten steel and thereby improve the performance of the steel.

[0029] In a specific embodiment of the present invention, in step S1, bottom blowing of argon gas for stirring can be performed during the converter refining and steelmaking process, thereby promoting the floating of inclusions in the steel.

[0030] In a specific embodiment of the present invention, bottom blowing argon stirring is performed throughout the LF refining process of step S2, in order to promote the floating of inclusions in the steel and to make the temperature and chemical composition of the molten steel uniform.

[0031] Preferably, step S1 further includes the steps of blast furnace iron smelting and desulfurization pretreatment before converter smelting.

[0032] Preferably, the continuous casting speed in step S4 is 1.2±0.1 m / min.

[0033] Preferably, the temperature of the continuous casting straightening zone in step S4 is >900°C.

[0034] In a specific embodiment of the present invention, after the continuous casting in step S4, the steps of stack cooling, heating, descaling, rough rolling, finishing rolling, laminar cooling, coiling, air cooling, uncoiling and straightening, cut-to-length cutting, printing and marking, quenching, tempering, straightening, inspection, and warehousing are also included.

[0035] In a specific embodiment of the present invention, the starting rolling temperature during the rough rolling is 1150-1200°C.

[0036] In a specific embodiment of the present invention, the number of rolling passes during the rough rolling is 7, and the final rolling temperature is 1070±30°C.

[0037] In a specific embodiment of the present invention, during air cooling, a cooling bed is used for natural air cooling to room temperature.

[0038] The present invention also protects the use of the above-mentioned high wear-resistant steel in the preparation of electric power fittings.

[0039] The present invention also protects an electric power fitting hanging plate made of the above-mentioned high wear-resistant steel.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The high wear-resistant steel provided by the present invention has a yield strength of ≥900MPa, a tensile strength of ≥1200MPa, an elongation after fracture of ≥12%, and the measured ratio of the yield strength to the tensile strength of the steel is about 0.75, which meets the requirement that the material yield strength ratio of the connecting hardware parts is not greater than 0.8. At the same time, the wear resistance of the steel is improved by more than 2 times, and it has broad prospects in improving the outdoor service life of the connecting hardware. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figures 1 to 3All of them are load-displacement curves of the high wear-resistant steel obtained in Example 1 of the present invention (experimental results repeated 3 times). DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0044] Examples 1 to 3 and Comparative Examples 1 to 5

[0045] This embodiment and comparative example provide a method for preparing a series of steels with different chemical compositions and thicknesses, comprising the following steps:

[0046] S1. Converter smelting: using molten iron and scrap steel for smelting, the molten iron S is less than or equal to 0.035Wt%; the converter tapping end point C is greater than or equal to 0.15Wt%, P is less than or equal to 0.020Wt%, and ferrosilicon, ferromanganese and ferrochrome are added as needed during tapping, and argon is blown bottom during tapping; blast furnace molten iron smelting and desulfurization pretreatment are performed before converter smelting;

[0047] S2. LF refining, during the refining process of the molten steel into the LF furnace, titanium iron, boron iron and rare earth (including La element) alloy are added as needed, and the LF refining process is carried out with bottom blowing of argon gas stirring throughout the whole process;

[0048] S3.RH refining;

[0049] S4. Continuous casting. The continuous casting process adopts full-process protective pouring. The continuous casting pulling speed is 1.2±0.1m / min, and the temperature of the ingot straightening zone is >900℃. After the continuous casting is completed, the billet is piled cooled, heated, descaled, rough rolled, finished rolled, laminar cooled, coiled, air cooled, uncoiled and straightened, cut to length, printed with markings, quenched, tempered, straightened, inspected, and put into storage. The starting temperature of rough rolling is 1175℃, the rough rolling passes are 7 times, and the final rolling temperature is 1070±30℃. During air cooling, the cooling bed is used for natural air cooling to room temperature.

[0050] The chemical composition content and thickness of each steel obtained in Examples 1 to 3 and Comparative Examples 1 to 5 are shown in Table 1:

[0051] Table 1 Chemical composition (by mass percentage / %) and thickness of the steel obtained in each embodiment and comparative example

[0052] Group thickness C Mn Si Cr Ti B RE(La) Example 1 5mm 0.18 1.16 0.19 0.17 0.02 0.0013 0.04 Example 2 10mm 0.18 1.15 0.12 0.24 0.01 0.0014 0.04 Example 3 20mm 0.17 1.23 0.11 0.21 0.02 0.0018 0.03 Comparative Example 1 5mm 0.18 1.21 0.14 0.40 0.01 0.0018 0.03 Comparative Example 2 5mm 0.19 1.23 0.20 0.24 0.06 0.0014 0.05 Comparative Example 3 5mm 0.18 1.16 0.12 0 0.02 0.0015 0.04 Comparative Example 4 5mm 0.17 1.22 0.14 0.20 0 0.0018 0.03 Comparative Example 5 5mm 0.18 1.22 0.19 0.23 0.02 0.0016 0

[0053] Note: The N content in the steel obtained in the above examples and comparative examples all satisfies ≤0.006Wt%.

[0054] The amount of substances that need to be added in Examples 1 to 3 and Comparative Examples 1 to 5 is calculated as shown in Table 2 below:

[0055] Table 2 Calculation method of the amount of additional substances to be added to each steel material in Examples 1 to 3 and Comparative Examples 1 to 5

[0056]

[0057] Comparative Example 6

[0058] A low-alloy high-strength steel commonly used in power fittings, specifically Q355 steel, with a thickness of 5 mm.

[0059] Performance Testing

[0060] According to GB / T228.1-2021 "Metallic Materials Tensile Test Part 1: Room Temperature Test Method" standard, the samples were prepared and the yield strength (R eL ), tensile strength (R m ) and elongation after break (A).

[0061] The wear resistance of steel samples was tested according to ASTM G65-04 "Standard Test Method for Abrasion Using Dry Sand / Rubber Wheel Apparatus".

[0062] Steel chemical composition testing: GB / T 4336-2002 "Spark source atomic emission spectrometric analysis method for carbon steel and medium and low alloy steel (conventional method)"

[0063] The performance test data are shown in Tables 3 to 4 below. Figures 1 to 3 As shown:

[0064] Table 3 Mechanical properties of steel materials in various embodiments and comparative examples

[0065] Group <![CDATA[R eL / MPa]]> <![CDATA[R m / MPa]]> <![CDATA[R eL / R m ]]> A / ％ Example 1 933 1261 0.74 13 Example 2 946 1293 0.72 12 Example 3 917 1256 0.73 13 Comparative Example 1 1185 1382 0.86 11 Comparative Example 2 984 1310 0.75 11 Comparative Example 3 891 1222 0.73 15 Comparative Example 4 895 1243 0.72 15 Comparative Example 5 941 1272 0.74 11

[0066] Table 4 Wear resistance of steel materials in Example 1 and Comparative Example 6

[0067] Group Wear resistance Example 1 2.39835 Comparative Example 6 1

[0068] According to the relevant provisions of the national industry standard DL / T759-2009 "Connection Hardware" and related enterprise standards, it can be seen from Table 3 that the steel plate for the high wear-resistant power connection hardware hanging plate in the present invention has good strength, toughness and wear resistance. Among them, the yield strength reaches 917~946MPa, the tensile strength reaches 1256~1293MPa, the yield strength ratio is ≤0.8, and the elongation after fracture is ≥12%; while meeting the mechanical performance requirements of the power connection hardware hanging plate, the high wear-resistant steel provided by the present invention has greatly improved wear resistance compared with the traditional material Q355, and the wear resistance is improved by about 2 times, which greatly improves the safety performance of the product. It should be noted that although the specifications of the steel obtained in Examples 1 to 3 of the present invention are not consistent, the thickness change of the steel in the present invention has no obvious effect on the performance.

[0069] According to Tables 1 and 3, the Cr content of the steel in Comparative Example 1 is too high, resulting in a higher strength of the steel, but a decrease in toughness; the Ti content of the steel in Comparative Example 2 is too high, resulting in the aggregation and coarsening of the originally fine dispersed phase Ti(C,N), so that both the toughness and strength of the steel are reduced. Combining the data of Comparative Examples 3 to 5, it can be seen that in order to ensure that the steel has both excellent strength and toughness, and then ensure that the steel has excellent wear resistance, the three elements of Ti, Cr and RE are indispensable.

[0070] According to Table 4, the wear resistance of the steel provided by the present invention is more than doubled compared to the traditional Q355 material used for preparing electrical hardware.

[0071] Figures 1 to 3 This is a load-displacement curve of the high-wear-resistant steel provided in Example 1 of the present invention (repeated 3 times). The load-displacement curve of the present invention is prepared and tested in accordance with the standard GB / T228.1-2021 "Tensile test of metallic materials Part 1: Room temperature test method". After the maximum load is obtained in the test, the yield strength and tensile strength of the steel sample can be obtained by dividing it by the cross-sectional area of ​​the sample. According to calculations, the high-wear-resistant steel provided by the present invention has a yield strength of 917 to 946 MPa and a tensile strength of 1256 to 1293 MPa.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A highly wear-resistant steel material, characterized in that: The chemical composition calculated by mass percentage is as follows: C: 0.16~0.19Wt%, Mn: 1.1~1.3Wt%, Si: 0.08~0.20Wt%, Cr: 0.15~0.25Wt%, Ti: 0.01~0.03Wt%, B: 0.0012~0.0020Wt%, N: ≤0.006Wt%, RE: 0.02~0.05Wt%, the remainder is Fe and inevitable trace elements.

2. The high wear-resistant steel material according to claim 1, characterized in that: The chemical composition calculated by mass percentage is as follows: C: 0.17~0.18Wt%, Mn: 1.15~1.23Wt%, Si: 0.11~0.19Wt%, Cr: 0.17~0.24Wt%, Ti: 0.01~0.02Wt%, B: 0.0013~0.0018Wt%, N: ≤0.006Wt%, RE: 0.03~0.04Wt%, the balance is Fe and inevitable trace elements.

3. The highly wear-resistant steel material according to claim 1 or 2, characterized in that: The mass ratio of Cr to Ti and RE in the chemical composition of the steel is Cr:(Ti+RE)=(4.5-5):

1.

4. The high wear-resistant steel material according to claim 3, characterized in that: The mass ratio of Cr to Ti in the chemical composition of the steel is Cr:Ti=(23-24):

1.

5. The high wear-resistant steel material according to claim 4, characterized in that: The chemical composition calculated by mass percentage is as follows: C: 0.18Wt%, Mn: 1.15Wt%, Si: 0.12Wt%, Cr: 0.24Wt%, Ti: 0.01Wt%, B: 0.0014Wt%, N: ≤0.006Wt%, RE: 0.04Wt%, and the balance is Fe and inevitable trace elements.

6. The method for preparing the high wear-resistant steel according to any one of claims 1 to 5, characterized in that: The steps include: S1. Converter smelting: Molten steel is obtained by smelting molten iron and scrap steel. The molten iron entering the furnace requires S≤0.035Wt%; the converter tapping end point requires C≥0.15Wt%, P≤0.020Wt%, and ferrosilicon, ferromanganese and ferrochrome are added as needed during tapping; S2.LF refining, during the refining process after the molten steel enters the LF furnace, titanium iron, boron iron and rare earth alloy are added as needed; S3.RH refining; S4. Continuous casting, the continuous casting process adopts full-process protective pouring.

7. The method for preparing the highly wear-resistant steel material according to claim 6, characterized in that: Step S1 also includes the steps of blast furnace molten iron smelting and desulfurization pretreatment before converter smelting.

8. The method for preparing the highly wear-resistant steel material according to claim 6, characterized in that: The continuous casting speed in step S4 is 1.2±0.1 m / min.

9. Use of the high wear-resistant steel material according to any one of claims 1 to 5 in the preparation of electric power fittings.

10. An electric power fitting hanging plate made of the highly wear-resistant steel material according to any one of claims 1 to 5.

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