High-strength wear-resistant steel and method for manufacturing same

Abstract

The application discloses a kind of high-strength wear-resistant steel and preparation method thereof, and the chemical composition and mass percentage of high-strength wear-resistant steel are as follows: C: 0.15-0.36%, Mn: 1.5-4.0%, Si: 0.30-0.60%, Cr: 0.30-0.80%, Cu: 0.10-0.30%, P≤0.020%, S≤0.020%, and the rest is Fe and inevitable impurities.The application is suitable for the manufacturing field of high-strength wear-resistant steel.According to actual needs, by optimizing the ratio of the chemical composition of high-strength wear-resistant steel, the type and content of micro-alloy elements are reduced, a kind of high-strength wear-resistant steel mainly composed of surface martensite+behenite and core ferrite+pearlite is prepared, which has the performance of high surface hardness, good wear resistance, high core strength, good plasticity and toughness.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical materials and relates to a high-strength wear-resistant steel and its preparation method. Background Technology

[0002] With the development of my country's construction machinery industry, the demand for heavy construction machinery such as concrete pump trucks, excavators, and cranes is gradually increasing. Construction machinery vehicles are generally made of steel parts. To improve the strength of steel, alloying elements are usually added to alloy the steel, and then its strength is improved through heat treatment methods such as controlled rolling, controlled cooling, quenching and tempering. Alloy structural steel is widely used in the manufacture of various parts and structural components for automobiles, tractors, ships, steam turbines, and construction machinery equipment. Currently, alloy steels such as high-strength steel series have high strength but poor wear resistance; while wear-resistant steel has good wear resistance and hardness but poor toughness. There is a lack of a high-strength wear-resistant steel that combines high strength, high toughness, and good wear resistance.

[0003] Currently, existing technology 1 (CN201710191820.7) discloses a high-strength wear-resistant steel and its manufacturing method. The chemical composition by mass percentage is: silicon 5-10%, tungsten 3-6%, manganese 3-6%, phosphorus 2-5%, sulfur 2-5%, carbon 0.2-3%, niobium 0.1-3%, titanium 0.1-2%, molybdenum 3-10%, chromium 2-6%, boron 1-4%, binder 3-8%, wear-resistant agent 0.5-5%, flame retardant 0.1-3%, forming agent 1-5%, reinforcing agent 0.2-6%, and antioxidant 1-5%, with the balance being iron. This invention patent contains a large variety and high content of alloys such as tungsten, manganese, niobium, molybdenum, and chromium. It does not utilize heat treatment to fully exploit the role of the alloying elements, leading to resource waste and a significant increase in steel costs, making large-scale application difficult in practice. Summary of the Invention

[0004] Objective: To address the shortcomings of existing technologies, this invention proposes a high-strength wear-resistant steel and its preparation method. Based on actual needs, the chemical composition of the high-strength wear-resistant steel is optimized to reduce the types and contents of microalloying elements, resulting in steel with high surface hardness, good wear resistance, high core strength, and good ductility and toughness.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] In the first aspect, this application provides a high-strength wear-resistant steel with the following chemical composition and mass percentage: C: 0.15-0.36%, Mn: 1.5-4.0%, Si: 0.30-0.60%, Cr: 0.30-0.80%, Cu: 0.10-0.30%, P≤0.020%, S≤0.020%, with the remainder being Fe and unavoidable impurities.

[0007] Secondly, this application also provides a method for preparing the high-strength steel pipe, comprising the following steps:

[0008] S1) Provide raw steel billets, the chemical composition and mass percentage of which are as follows: C: 0.15-0.36%, Mn: 1.5-4.0%, Si: 0.30-0.60%, Cr: 0.30-0.80%, Cu: 0.10-0.30%, P≤0.020%, S≤0.020%, with the remainder being Fe and unavoidable impurities. The raw steel billets are then smelted and melted to obtain molten steel.

[0009] S2) The molten steel is cast and hot-rolled to obtain hot-rolled steel;

[0010] S3) The obtained hot-rolled steel is quenched to obtain high-strength wear-resistant steel.

[0011] In some implementations, in step S1), the smelting is carried out in a vacuum induction furnace, and electromagnetic stirring is performed during the smelting process.

[0012] In some implementations, in step S2), casting is performed using a continuous casting machine.

[0013] In some implementations, in step S2), hot rolling is carried out at a temperature of 920–1080°C, and the temperature after hot rolling is not lower than 700°C.

[0014] In some implementations, in step S2), the hot rolling is performed in multiple passes, with the first pass hot rolling 20% ​​to 40%, and each subsequent pass hot rolling 5% to 20%, for a total deformation of 60% to 80%.

[0015] In some implementations, in step S3), quenching is performed using online induction quenching.

[0016] In some implementations, in step S3), the online induction hardening adopts one or more of the following: power frequency, low frequency, medium frequency, high frequency and ultra-high frequency induction hardening, and the cooling method adopts one or two of the following: water, PAG, oil and liquid nitrogen.

[0017] In some implementations, the high-strength wear-resistant steel has one or more of the following mechanical properties:

[0018] (1) Tensile strength > 1050 MPa;

[0019] (2) Lower yield strength or specified plastic elongation strength > 860 MPa;

[0020] (3) Elongation after fracture > 12.5%;

[0021] (4) Impact energy at room temperature > 132.0 KV² / J;

[0022] (5) Impact energy at 0℃ > 109KV2 / J;

[0023] (6) The impact energy at -40℃ is >98KV2 / J, and the impact energy does not decrease significantly with decreasing temperature;

[0024] (7) Surface hardness 45.6-49.7 HRC;

[0025] (8) Wear amount < 0.250g.

[0026] Beneficial effects:

[0027] a) By optimizing the chemical composition, the types and contents of microalloying elements can be reduced to meet the requirements of different performance characteristics.

[0028] b) The preparation method of the present invention uses an online induction heat treatment method, which can reduce energy consumption and cost, and is conducive to realizing industrial production.

[0029] c) A high-strength wear-resistant steel is prepared by smelting, rolling and online induction heat treatment. It is mainly composed of surface martensite + bainite + highly dispersed ultrafine carbides and core ferrite + pearlite. It has the properties of high surface hardness, good wear resistance, high core strength and good plasticity and toughness. Detailed Implementation

[0030] Example 1

[0031] A high-strength wear-resistant steel, by mass percentage of chemical composition, has the following composition: C: 0.16%, Mn: 2.0%, Si: 0.60%, Cr: 0.75%, Cu: 0.15%, P: 0.015%, S: 0.020%, with the remainder being Fe and unavoidable impurities.

[0032] S1) Smelting: Smelting is carried out according to the composition ratio, using a vacuum induction furnace, and electromagnetic stirring is carried out during the smelting process.

[0033] S2) Continuous casting and rolling: The molten steel is poured into a continuous casting machine to cast steel billets. After being kept at a certain temperature, the billets are hot rolled in multiple passes at 1050℃. The first hot rolling is 30%, and each subsequent hot rolling is 8%, with a total deformation of 75%. The temperature of the steel after hot rolling is not lower than 800℃.

[0034] S3) Induction hardening: The hot-rolled steel with a temperature of not less than 780℃ is subjected to online power frequency + ultra-high frequency induction hardening treatment. First, water quenching is performed to 300-400℃, then PAG quenching liquid is used to cool to room temperature, and finally liquid nitrogen is used to cool for 12 hours to obtain high-strength wear-resistant steel.

[0035] Example 2

[0036] A high-strength wear-resistant steel, by mass percentage of chemical composition, has the following composition: C: 0.33%, Mn: 3.5%, Si: 0.30%, Cr: 0.40%, Cu: 0.30%, P: 0.010%, S: 0.010%, with the remainder being Fe and unavoidable impurities.

[0037] S1) Smelting: Smelting is carried out according to the composition ratio, using a vacuum induction furnace, and electromagnetic stirring is carried out during the smelting process.

[0038] S2) Continuous casting and rolling: The molten steel is poured into a continuous casting machine to cast steel billets. After being kept at a certain temperature, the billets are hot rolled in multiple passes at 950℃. The first hot rolling is 20%, and each subsequent hot rolling is 16%, with a total deformation of 65%. The temperature of the steel after hot rolling is not lower than 720℃.

[0039] S3) Induction hardening: The hot-rolled steel with a temperature of not less than 720℃ is subjected to online low-frequency + medium-frequency induction hardening treatment. First, it is cooled to 300-400℃ with PAG quenching liquid, then cooled to room temperature with water, and finally cooled with liquid nitrogen for 10 hours to obtain high-strength wear-resistant steel.

[0040] Example 3

[0041] A high-strength wear-resistant steel, by mass percentage of chemical composition, has the following composition: C: 0.23%, Mn: 2.5%, Si: 0.40%, Cr: 0.40%, Cu: 0.20%, P: 0.010%, S: 0.015%, with the remainder being Fe and unavoidable impurities.

[0042] S1) Smelting: Smelting is carried out according to the composition ratio, using a vacuum induction furnace, and electromagnetic stirring is carried out during the melting process;

[0043] S2) Continuous casting and rolling: The molten steel is poured into a continuous casting machine to cast steel billets. After being kept at a certain temperature, the billets are hot rolled in multiple passes at 1000℃. The first hot rolling is 25%, and each subsequent hot rolling is 10%, with a total deformation of 70%. The temperature of the steel after hot rolling is not lower than 750℃.

[0044] S3) Induction hardening: The hot-rolled steel obtained at a temperature of not less than 720℃ is subjected to online medium-frequency + high-frequency induction hardening treatment, then cooled to room temperature with water, and then cooled with liquid nitrogen for 15 hours to obtain high-strength wear-resistant steel.

[0045] Example 4

[0046] A high-strength wear-resistant steel, based on the chemical composition by mass percentage, has the following composition: C: 0.15%, Mn: 4.0%, Si: 0.60%, Cr: 0.30%, Cu: 0.30%, P: 0.010%, S: 0.010%, with the remainder being Fe and unavoidable impurities.

[0047] S1) Smelting: Smelting is carried out according to the composition ratio, using a vacuum induction furnace, and electromagnetic stirring is carried out during the smelting process.

[0048] S2) Continuous casting and rolling: The molten steel is poured into a continuous casting machine to cast steel billets. After being kept at a certain temperature, the billets are hot rolled in multiple passes at 950℃. The first hot rolling is 20%, and each subsequent hot rolling is 16%, with a total deformation of 65%. The temperature of the steel after hot rolling is not lower than 720℃.

[0049] S3) Induction hardening: The hot-rolled steel with a temperature of not less than 720℃ is subjected to online low-frequency + medium-frequency induction hardening treatment. First, it is cooled to 300-400℃ with PAG quenching liquid, then cooled to room temperature with water, and finally cooled with liquid nitrogen for 10 hours to obtain high-strength wear-resistant steel.

[0050] Example 5

[0051] A high-strength wear-resistant steel, by mass percentage of chemical composition, has the following composition: C: 0.36%, Mn: 1.5%, Si: 0.30%, Cr: 0.80%, Cu: 0.10%, P: 0.010%, S: 0.010%, with the remainder being Fe and unavoidable impurities.

[0052] S1) Smelting: Smelting is carried out according to the composition ratio, using a vacuum induction furnace, and electromagnetic stirring is carried out during the smelting process.

[0053] S2) Continuous casting and rolling: The molten steel is poured into a continuous casting machine to cast steel billets. After being kept at a certain temperature, the billets are hot rolled in multiple passes at 950℃. The first hot rolling is 20%, and each subsequent hot rolling is 16%, with a total deformation of 65%. The temperature of the steel after hot rolling is not lower than 720℃.

[0054] S3) Induction hardening: The hot-rolled steel with a temperature of not less than 720℃ is subjected to online low-frequency + medium-frequency induction hardening treatment. First, it is cooled to 300-400℃ with PAG quenching liquid, then cooled to room temperature with water, and finally cooled with liquid nitrogen for 10 hours to obtain high-strength wear-resistant steel.

[0055] Example 6

[0056] Chemical composition of a high-strength wear-resistant steel (refer to Implementation Case 2).

[0057] S1) Smelting: Smelting is carried out according to the composition ratio, using a vacuum induction furnace, and electromagnetic stirring is carried out during the smelting process.

[0058] S2) Continuous casting and rolling: The molten steel is poured into a continuous casting machine to cast steel billets. After being kept at a certain temperature, the billets are hot rolled in multiple passes at 950℃. The first hot rolling is 20%, and each subsequent hot rolling is 16%, with a total deformation of 65%. After hot rolling, the temperature of the steel is not lower than 680℃.

[0059] S3) Induction hardening: The hot-rolled steel with a temperature of not less than 680℃ is subjected to online low-frequency + medium-frequency induction hardening treatment. First, it is cooled to 300-400℃ with PAG quenching liquid, then cooled to room temperature with water, and finally cooled with liquid nitrogen for 10 hours to obtain high-strength wear-resistant steel.

[0060] Example 7

[0061] Chemical composition of a high-strength wear-resistant steel (refer to Implementation Case 2).

[0062] S1) Smelting: Smelting is carried out according to the composition ratio, using a vacuum induction furnace, and electromagnetic stirring is carried out during the smelting process.

[0063] S2) Continuous casting and rolling: The molten steel is poured into a continuous casting machine to cast steel billets. After being kept at a certain temperature, the billets are hot rolled in multiple passes at 900℃. The first hot rolling is 20%, and each subsequent hot rolling is 16%, with a total deformation of 65%. The temperature of the steel after hot rolling is not lower than 720℃.

[0064] S3) Induction hardening: The hot-rolled steel with a temperature of not less than 720℃ is subjected to online low-frequency + medium-frequency induction hardening treatment. First, it is cooled to 300-400℃ with PAG quenching liquid, then cooled to room temperature with water, and finally cooled with liquid nitrogen for 10 hours to obtain high-strength wear-resistant steel.

[0065] Example 8

[0066] Chemical composition of a high-strength wear-resistant steel (refer to Implementation Case 2).

[0067] S1) Smelting: Smelting is carried out according to the composition ratio, using a vacuum induction furnace, and electromagnetic stirring is carried out during the smelting process.

[0068] S2) Continuous casting and rolling: The molten steel is poured into a continuous casting machine to cast steel billets. After being kept at a certain temperature, the billets are hot rolled in multiple passes at 1120℃. The first hot rolling is 20%, and each subsequent hot rolling is 16%, with a total deformation of 65%. The temperature of the steel after hot rolling is not lower than 720℃.

[0069] S3) Induction hardening: The hot-rolled steel with a temperature of not less than 720℃ is subjected to online low-frequency + medium-frequency induction hardening treatment. First, it is cooled to 300-400℃ with PAG quenching liquid, then cooled to room temperature with water, and finally cooled with liquid nitrogen for 10 hours to obtain high-strength wear-resistant steel.

[0070] Comparative Example 1

[0071] A high-strength wear-resistant steel, based on the chemical composition by mass percentage, has the following composition: C: 0.16%, Mn: 5%, Si: 1.0%, Cr: 0.75%, Cu: 0.15%, P: 0.015%, S: 0.020%, with the remainder being Fe and unavoidable impurities.

[0072] The preparation method is described in Implementation Case 1.

[0073] Comparative Example 2

[0074] A high-strength wear-resistant steel, by mass percentage of chemical composition, has the following composition: C: 0.16%, Mn: 2.0%, Si: 0.60%, Cr: 1.20%, Cu: 0.50%, P: 0.015%, S: 0.020%, with the remainder being Fe and unavoidable impurities.

[0075] The preparation method is described in Implementation Case 1.

[0076] Comparative Example 3 (Example 3 of CN201710191820.7)

[0077] This embodiment describes a high-strength wear-resistant steel, which is mainly prepared by mixing the following components in parts by weight: silicon 8%, tungsten 5%, manganese 5%, phosphorus 4%, sulfur 3%, carbon 1%, niobium 2%, titanium 1%, molybdenum 6%, chromium 4%, boron 2%, binder 5%, wear-resistant agent 2.5%, flame retardant 2%, forming agent 3%, reinforcing agent 4%, and antioxidant 3%, with the balance being iron.

[0078] The binder is ultrafine silica powder with a mesh size of 1300 mesh. The wear-resistant agent is a uniform mixture of polycarbonate and vanadium at a weight ratio of 1:0.2. The flame retardant is a uniform mixture of polyvinyl chloride and decabromodiphenyl ethane at a weight ratio of 1:5. The molding agent is a mixture of polyethylene glycol and paraffin wax at a weight ratio of 2:1. The reinforcing agent is an acrylonitrile-butadiene-styrene copolymer. The antioxidant is a mixture of tert-butyl-p-hydroxyanisole and tert-butylhydroquinone at a weight ratio of 1:1. This embodiment describes a method for manufacturing the high-strength wear-resistant steel, comprising the following steps:

[0079] S1) Weigh the above-mentioned parts by weight of raw materials;

[0080] S2) Weigh out silicon, tungsten, manganese, phosphorus, sulfur, carbon, niobium, titanium, molybdenum, chromium, boron, forming agent, reinforcing agent, one-third wear-resistant agent, one-third flame retardant and one-third antioxidant and add them to iron. After stirring evenly, add ultrafine silicon powder binder with good adhesion and can improve the density of steel and bind it. Then, sinter it at high temperature, where the high temperature sintering temperature is 1100℃ and the time is 4 hours to obtain shaped alloy steel.

[0081] S3) The remaining wear-resistant agent, flame retardant and antioxidant are mixed evenly and then sprayed onto the surface of the shaped alloy steel obtained in step S2) through a spraying machine. Then, it is hot-pressed and sintered, wherein the pressure selected for hot-pressing and sintering is 35MPa, and finally the high-strength wear-resistant steel is obtained.

[0082] Tensile strength, lower yield strength ReL Or specify the plastic elongation strength R p0.2 The elongation after fracture was determined according to GB / T 228.1-2021, the impact energy was determined according to GB / T 229-2020, the hardness was determined according to GB / T230.1-2018, and the wear performance was tested using an MMW-1 type pin-disc friction and wear tester with a test loading force of 300N, a wear time of 7200s, and a rotation speed of 180r / min.

[0083] Table 1 Physical and mechanical properties of high-strength wear-resistant steel

[0084]

[0085] As shown in Table 1, the high-strength wear-resistant steel prepared by adjusting the chemical composition and optimizing the ratio in the embodiments of the present invention has the following properties: (1) tensile strength > 1050 MPa; (2) lower yield strength or specified plastic elongation strength > 860 MPa; (3) elongation after fracture > 12.5%; (4) impact energy at room temperature > 132.0 KV2 / J; (5) impact energy at 0℃ > 109 KV2 / J; (6) impact energy at -40℃ > 98 KV2 / J, and the impact energy does not decrease significantly with the decrease of temperature; (7) surface hardness 45.6-49.7 HRC; (8) wear amount < 0.250 g. The compressive strength, lower yield strength or specified plastic extension strength, elongation after fracture, impact energy, surface hardness, and wear amount are significantly improved compared with Comparative Examples 1, 2, and 3 (Prior Art 1). It can be seen that the present invention optimizes the chemical composition ratio, reduces the types and contents of microalloying elements, and prepares a high-strength wear-resistant steel mainly composed of surface martensite + bainite + highly dispersed ultrafine carbides and core ferrite + pearlite by smelting, rolling, and online induction heat treatment. It has the properties of high surface hardness, good wear resistance, high core strength, and good plasticity and toughness.

[0086] In the above embodiments of the present invention, the sequence numbers or order of the embodiments are merely for descriptive purposes and do not represent the superiority or inferiority of the embodiments. The descriptions of each embodiment have their own emphasis; for parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. The technical means disclosed in the present invention are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. The present invention has been disclosed above with reference to preferred embodiments, but it is not intended to limit the present invention. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for preparing high-strength wear-resistant steel, characterized in that, Includes the following steps: S1) Provide raw steel billets, the chemical composition and mass percentage of which are as follows: C: 0.15-0.36%, Mn: 1.5-4.0% but not exceeding 1.5%, Si: 0.30-0.60%, Cr: 0.30-0.80%, Cu: 0.10-0.30%, P≤0.020%, S≤0.020%, with the remainder being Fe and unavoidable impurities; smelt the raw steel billets to obtain molten steel; S2) The molten steel is cast and hot-rolled to obtain hot-rolled steel; wherein the hot rolling is carried out at a temperature of 920 to 1080°C and the temperature after hot rolling is not lower than 700°C; the hot rolling adopts multi-pass hot rolling, the first hot rolling is 20% to 40%, and each subsequent hot rolling is 5% to 20%, with a total deformation of 60% to 80%. S3) The hot-rolled steel obtained at a temperature of not less than 700℃ is subjected to online induction hardening. The online induction hardening adopts one or more of the following: power frequency, low frequency, medium frequency, high frequency and ultra-high frequency induction hardening. The cooling method is first to cool to room temperature by one or two of the following: water, PAG, oil, and then cooling with liquid nitrogen to obtain high-strength wear-resistant steel mainly composed of surface martensite + bainite + dispersed ultrafine carbides and core ferrite + pearlite.

2. The method according to claim 1, characterized in that, In step S1), the smelting is carried out in a vacuum induction furnace, and electromagnetic stirring is used during the smelting process.

3. The method according to claim 1, characterized in that, In step S2), the casting is carried out using a continuous casting machine.

4. A high-strength wear-resistant steel, prepared by the method described in any one of claims 1-3.

5. The high-strength wear-resistant steel according to claim 4, characterized in that, It possesses the following mechanical properties: (1) Tensile strength > 1050 MPa; (2) Lower yield strength or specified plastic elongation strength > 860 MPa; (3) Elongation after fracture > 12.5%; (4) Impact energy at room temperature > 132.0 KV² / J; (5) Impact energy at 0℃ > 109 kV² / J; (6) The impact energy at -40℃ is >98KV2 / J, and the impact energy does not decrease significantly with decreasing temperature; (7) Surface hardness 45.6-49.7 HRC; (8) Wear amount < 0.250g.

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