A vanadium-containing low-carbon medium-chromium alloy steel, and its preparation method and application

Abstract

The present invention provides a vanadium-containing low-carbon medium-chromium alloy steel, a preparation method and application thereof, and relates to the technical field of alloy steel. The vanadium-containing low-carbon medium-chromium alloy steel, in terms of weight percentage, has the following chemical compositions: Cr 4.0% to 5.0%, C 0.2% to 0.3%, V 0.02% to 0.4%, Mn 1.1% to 1.3%, Si 1.3% to 1.4%, Mo 0.5% to 0.6%, Nb 0.04% to 0.06%, P≤0.04%, S≤0.04%, and the remainder is iron and trace elements that are unavoidable in the manufacturing process. The vanadium-containing low-carbon medium-chromium alloy steel provided by the present invention has excellent corrosion resistance, and the impact-corrosion-abrasive wear properties are significantly improved, and can be applied to wet ball mill liners, reamer teeth and shovel teeth in corrosive environments.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy steels, and in particular to a vanadium-containing low-carbon medium-chromium alloy steel, and a preparation method and application thereof. Background Art

[0002] Wear-resistant cast alloy steel has many classification methods. According to the carbon content, it can be divided into low-carbon, medium-carbon and high-carbon wear-resistant steel; according to the alloy element content, it can be divided into low-alloy, medium-alloy and high-alloy wear-resistant steel; according to the organizational composition, it can be divided into austenite, pearlite, bainite and martensite wear-resistant steel. Unlike wear-resistant manganese steel and cast iron materials, alloy steel has a wide range of alloy types and adjustable ranges, so its hardness, toughness and strength can be coordinated and matched, so it has gradually become an important wear-resistant material that is expected to replace wear-resistant manganese steel and cast iron materials. At present, wear-resistant cast alloy steel is widely used in equipment such as excavator bucket teeth, cement plants and thermal power plant ball mill liners, small and medium-sized hammer crusher hammers, and wear-resistant pipes.

[0003] The basic elements in wear-resistant cast alloy steel include C, Cr, Mn, Si and impurity elements such as P and S. On this basis, Ni, Mo, V, Ti, W, Nb, Co, Cu, Al, B, N and Re are added according to specific needs. The purpose of adding alloy elements to wear-resistant cast alloy steel is to improve the performance indicators of the material such as hardenability, strength, hardness, toughness and wear resistance. However, the current alloy steel cannot have corrosion resistance, toughness, hardness and wear resistance at the same time.

[0004] Therefore, developing an alloy steel with ideal corrosion resistance, toughness, hardness and wear resistance is a technical problem that urgently needs to be solved. Summary of the invention

[0005] The purpose of the present invention includes providing a vanadium-containing low-carbon medium-chromium alloy steel and a preparation method thereof, aiming to improve the corrosion resistance, toughness, hardness and wear resistance of the alloy steel.

[0006] Another object of the present invention is to provide the use of vanadium-containing low-carbon medium-chromium alloy steel in the preparation of wear-resistant components.

[0007] The embodiments of the present invention can be implemented as follows:

[0008] In a first aspect, the present invention provides a vanadium-containing low-carbon medium-chromium alloy steel, whose chemical composition, measured by weight percentage, is: Cr 4.0%-5.0%, C 0.2%-0.3%, V 0.02%-0.4%, Mn 1.1%-1.3%, Si 1.3%-1.4%, Mo 0.5%-0.6%, Nb 0.04%-0.06%, P≤0.04%, S≤0.04%, and the balance is iron and inevitable trace elements in the manufacturing process.

[0009] In an optional embodiment, the chemical composition is, by weight percentage, Cr 4.1% to 4.3%, C 0.2% to 0.25%, V 0.1% to 0.35%, Mn 1.2% to 1.25%, Si 1.3% to 1.35%, Mo 0.5% to 0.6%, Nb 0.04% to 0.05%, P ≤ 0.04%, S ≤ 0.04%, and the remainder is iron and inevitable trace elements in the manufacturing process.

[0010] In a second aspect, the present invention provides a method for preparing the vanadium-containing low-carbon medium-chromium alloy steel in the aforementioned embodiment, so as to prepare the alloy steel from raw materials formulated according to chemical composition.

[0011] In an optional embodiment, the process includes: smelting, casting and heat treating the raw materials.

[0012] In an alternative embodiment, the raw materials include ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, ferroniobium, ferrovanadium and pig iron.

[0013] In an optional embodiment, the smelting and casting process includes: melting the raw materials and adjusting the composition of the molten steel, and then deoxidizing and removing impurities from the molten steel and transferring the molten steel for casting.

[0014] In an optional embodiment, the heat treatment process includes: one homogenization treatment, two two-phase region quenching, one high temperature quenching and one low temperature stress relief tempering.

[0015] In an optional embodiment, the treatment temperature of one homogenization treatment is 1030℃~1060℃, the treatment temperature of two two-phase zone quenching is 780℃~810℃, the treatment temperature of one high temperature quenching is 1090℃~1110℃, and the treatment temperature of one low temperature stress relief tempering is 100℃~250℃.

[0016] In an optional embodiment, the process of a homogenization treatment includes: firstly heating from room temperature to 600°C-700°C at a heating rate of 4°C / min-5°C / min and keeping warm for 1h-3h, then heating to 800°C-900°C at a heating rate of 3°C / min-4°C / min and keeping warm for 0.5h-1.5h, then heating to 1030°C-1060°C at a heating rate of 7°C / min-9°C / min and keeping warm for 3h-5h, and then air cooling;

[0017] Preferably, the two-phase quenching process includes: heating from room temperature to 780°C to 810°C and keeping the temperature for 1h to 3h, followed by oil cooling;

[0018] Preferably, the process of a high temperature quenching comprises: firstly heating from room temperature to 800°C-900°C at a heating rate of 7°C / min-8°C / min and keeping at that temperature for 1.0h-2.0h, then heating to 1090°C-1110°C at a heating rate of 9°C / min-10°C / min and keeping at that temperature for 1.0h-1.5h, and then oil cooling;

[0019] Preferably, the process of a low-temperature stress relief tempering comprises: firstly heating from room temperature to 100°C-220°C at a heating rate of 3°C / min-4°C / min and keeping the temperature for 1.0h-2.0h, and then air cooling.

[0020] In a third aspect, the present invention provides a use of the vanadium-containing low-carbon medium-chromium alloy steel in any one of the aforementioned embodiments or the vanadium-containing low-carbon medium-chromium alloy steel prepared by any one of the preparation methods in the aforementioned embodiments in preparing wear-resistant components;

[0021] Preferably, the wear-resistant component is selected from at least one of a wet ball mill liner, a reamer tooth and a shovel tooth.

[0022] The beneficial effects of the embodiments of the present invention include: introducing vanadium into low-carbon medium-chromium alloy steel, and optimizing the amount of vanadium element, the microalloying effect of vanadium element can be utilized to improve the toughness, hardness, corrosion resistance and wear resistance of low-carbon medium-chromium alloy steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 It is a comparison chart of the impact-corrosion-abrasive wear weight loss of the alloy steels prepared in each embodiment and comparative example. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiment of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described below. If the specific conditions are not specified in the embodiment, it is carried out according to the conditions recommended by the normal conditions or the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially. It should be noted that the features in the embodiments of the present invention can be combined with each other when there is no conflict.

[0026] The embodiment of the present invention provides a vanadium-containing low-carbon medium-chromium alloy steel, whose chemical composition, measured by weight percentage, is: Cr4.0%-5.0%, C 0.2%-0.3%, V 0.02%-0.4%, Mn 1.1%-1.3%, Si 1.3%-1.4%, Mo 0.5%-0.6%, Nb 0.04%-0.06%, P≤0.04%, S≤0.04%, and the balance is iron and inevitable trace elements in the manufacturing process.

[0027] It should be noted that by introducing vanadium into low-carbon medium-chromium alloy steel and adjusting the amount of each component, the vanadium element can regulate the structure of the low-carbon medium-chromium alloy steel, and the vanadium element can be used to regulate the matching of toughness-hardness-corrosion resistance of the low-carbon medium-chromium alloy steel.

[0028] By introducing vanadium into low-carbon medium-chromium alloys and optimizing the amount of vanadium, the microalloying effect of vanadium can be utilized to improve the toughness, hardness, corrosion resistance and wear resistance of low-carbon medium-chromium alloy steels.

[0029] Specifically, the Cr content can be 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, etc.; the C content can be 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, etc.; the V content can be 0.02%, 0.05%, 0.08%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, etc.; the Mn content can be 1.10%, The content of Si can be 1.30%, 1.31%, 1.32%, 1.33%, 1.34%, 1.35%, 1.36%, 1.37%, 1.38%, 1.39%, 1.40%, etc.; the content of Mo can be 0.50%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.60%, etc.; the content of Nb can be 0.040%, 0.045%, 0.050%, 0.055%, 0.060%, etc. The less the content of P and S, the better, and they need to be less than or equal to 0.04%. The inevitable trace elements in the manufacturing process refer to the elements inevitably introduced in the process of preparing alloy steel, and their specific content is far less than 0.04%. The specific types are not limited, and reference can be made to the types of impurities in existing alloy steels.

[0030] In a preferred embodiment, the chemical composition is as follows by weight percentage: Cr 4.1% to 4.3%, C 0.2% to 0.25%, V 0.1% to 0.35%, Mn 1.2% to 1.25%, Si 1.3% to 1.35%, Mo0.5% to 0.6%, Nb0.04% to 0.05%, P≤0.04%, S≤0.04%, and the balance is iron and trace elements that are inevitable in the manufacturing process. The comprehensive properties of the alloy steel can be further improved by further optimizing the content of each element.

[0031] The embodiment of the present invention also provides a method for preparing vanadium-containing low-carbon medium-chromium alloy steel, which is to prepare alloy steel from raw materials prepared according to chemical composition, specifically comprising the following steps:

[0032] S1. Ingredients

[0033] The ingredients are prepared according to the composition of the alloy steel. The raw materials used include ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, ferroniobium, ferrovanadium and pig iron. The specific amounts can be proportioned according to the element composition.

[0034] It should be noted that ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, ferroniobium, ferrovanadium and pig iron are all commercially available raw materials.

[0035] S2, smelting, casting

[0036] The raw materials are smelted and cast into shape. The specific process can refer to the existing technology and will not be described in detail here.

[0037] In some embodiments, the smelting and casting process includes: adjusting the composition of the molten steel after melting the raw materials, and then deoxidizing and removing impurities from the molten steel, and transferring the molten steel to cast the molten steel. After the raw materials are melted, the composition of the molten steel is tested, and the composition is adjusted according to the test results so that the element composition of the product is more in line with the expected target composition.

[0038] Specifically, deoxygenation and impurity removal can be carried out according to the situation, and the specific method is not limited. Existing means of deoxygenation and impurity removal can be used, and are not limited here.

[0039] S3. Heat treatment

[0040] The heat treatment process includes: one homogenization treatment, two two-phase zone quenching, one high-temperature quenching and one low-temperature stress relief tempering. The heat treatment process is optimized to improve the comprehensive performance of the product.

[0041] Furthermore, the treatment temperature of a homogenization treatment is 1030℃~1060℃, the treatment temperature of two two-phase quenching is 780℃~810℃, the treatment temperature of a high temperature quenching is 1090℃~1110℃, and the treatment temperature of a low temperature stress relief tempering is 100℃~250℃. Through a homogenization treatment, the elements are diffused to ensure the uniform distribution of elements in the product and eliminate the element segregation problem in the cast structure; through two two-phase quenching, the grains are refined; through a high temperature quenching, the hardness, strength and toughness of the product can be improved; and a low temperature stress relief tempering can remove the internal stress generated during the quenching process. By using microalloying and combining with a suitable heat treatment process, the impact-corrosion-abrasive wear resistance of vanadium-containing low-carbon medium-chromium alloy steel can be improved.

[0042] Specifically, the treatment temperature of a homogenization treatment may be 1030°C, 1040°C, 1050°C, 1060°C, etc., the treatment temperature of two two-phase zone quenchings may be 780°C, 790°C, 800°C, 810°C, etc., the treatment temperature of a high-temperature quenching may be 1090°C, 1095°C, 1100°C, 1105°C, 1110°C, etc., and the treatment temperature of a low-temperature stress relief tempering may be 100°C, 120°C, 150°C, 170°C, 200°C, 220°C, 250°C, etc.

[0043] In some embodiments, in order to achieve a better element dispersion effect, the process of a homogenization treatment includes: firstly heating from room temperature to 600℃~700℃ at a heating rate of 4℃ / min-5℃ / min and keeping warm for 1h-3h, then heating to 800℃~900℃ at a heating rate of 3℃ / min-4℃ / min and keeping warm for 0.5h-1.5h, then heating to 1030℃~1060℃ at a heating rate of 7℃ / min-9℃ / min and keeping warm for 3h-5h, and then air cooling. The heating process of a homogenization treatment is divided into three steps, firstly heating to 600℃~700℃ at a slower heating rate and keeping warm for a period of time, then heating to 800℃~900℃ and keeping warm for a period of time, and finally heating to 1030℃~1060℃ at a faster heating rate and keeping warm for a period of time. "Air cooling" refers to the process of taking the product that has been subjected to a homogenization treatment out of the heating furnace and cooling it naturally in the air.

[0044] Specifically, the temperature reached in the first step of heating can be 600°C, 650°C, 700°C, etc., and the insulation time can be 1h, 2h, 3h, etc.; the temperature reached in the second step of heating can be 800°C, 850°C, 900°C, etc., and the insulation time can be 0.5h, 1.0h, 1.5h, etc.; the temperature reached in the third step of heating can be 1030°C, 1040°C, 1050°C, 1060°C, etc., and the insulation time can be 3h, 4h, 5h, etc.

[0045] In some embodiments, in order to achieve a better effect of grain refinement, the process of two two-phase region quenching includes: heating from room temperature to 780°C~810°C and keeping warm for 1h-3h, followed by oil cooling. "Oil cooling" is a common heat treatment method, mainly used for quenching metal materials. In the oil cooling treatment, the metal sample heated to an appropriate temperature is quickly immersed in the quenching oil to quickly cool the sample. Specifically, during the two two-phase region quenching processes, the holding time can be 1h, 2h, 3h, etc.

[0046] In some embodiments, in order to further improve the comprehensive performance of the product, the process of a high-temperature quenching includes: firstly heating from room temperature to 800℃~900℃ at a heating rate of 7℃ / min-8℃ / min and keeping warm for 1.0h-2.0h, then heating to 1090℃~1110℃ at a heating rate of 9℃ / min-10℃ / min and keeping warm for 1.0h-1.5h, and then oil cooling. The heating process of a high-temperature quenching is divided into two stages. In the first stage, the temperature is raised from room temperature to 800℃~900℃ at a slower heating rate, and then the temperature is quickly raised to 1090℃~1110℃.

[0047] Specifically, during a high-temperature quenching process, the temperature reached in the first stage of heating can be controlled to be 800°C, 850°C, or 900°C, and the insulation time can be 1.0h, 1.5h, 2.0h, etc.; the insulation time in the second stage can be controlled to be 1.0h, 1.3h, 1.5h, etc.

[0048] In some embodiments, to better remove residual stress, a low-temperature stress relief annealing process includes: first heating from room temperature to 100°C to 220°C at a heating rate of 3°C / min-4°C / min, keeping the temperature for 1.0h-2.0h, and then air cooling. Specifically, the holding time can be 1.0h, 1.5h, 2.0h, etc.

[0049] The embodiment of the present invention also provides the use of the above-mentioned vanadium-containing low-carbon medium-chromium alloy steel in the preparation of wear-resistant components. Since the alloy steel has excellent toughness, hardness, corrosion resistance and wear resistance, the prepared wear-resistant components also have excellent performance.

[0050] Preferably, the wear-resistant component is selected from at least one of a wet ball mill liner, a reamer tooth and a shovel tooth, and can be prepared into any one or more of the above wear-resistant components.

[0051] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0052] Example 1

[0053] The present embodiment provides a vanadium-containing low-carbon medium-chromium alloy steel, whose chemical composition, in weight percentage, is: Cr4.3%, C 0.2%, V 0.33%, Mn 1.2%, Si 1.3%, Mo 0.54%, Nb 0.04%, P≤0.04%, S≤0.04%, and the balance is iron and inevitable trace elements in the manufacturing process.

[0054] This embodiment also provides a method for preparing vanadium-containing low-carbon medium-chromium alloy steel, comprising the following steps:

[0055] (1) The raw materials used include ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, ferroniobium, ferrovanadium and pig iron.

[0056] (2) The raw materials are heated to 1550°C, and the composition of the molten steel is tested and adjusted after the raw materials are melted. The raw materials are deoxidized by adding rare earth silicon calcium deoxidizer and impurities are removed by adding perlite slag forming agent. The raw materials are then transferred to a casting mold to obtain an alloy steel casting.

[0057] (3) After the casting is cooled, heat treatment is performed. Heat from room temperature to 650℃ at a heating rate of 4℃ / min and keep it for 2 hours, then heat it to 850℃ at a heating rate of 3℃ / min and keep it for 1 hour, and finally heat it to 1050℃ at a heating rate of 7℃ / min and keep it for 4 hours, then air cool it to complete a homogenization treatment. After the casting is cooled, it is directly heated from room temperature to 800℃ in the furnace and kept for 2 hours, then oil cooled. This process is repeated twice to complete two-phase zone quenching. After that, the casting is heated from room temperature to 850℃ in the furnace at a heating rate of 7℃ / min and kept for 1.5 hours, then heated to 1100℃ at a heating rate of 9℃ / min and kept for 1 hour, then oil cooled to complete a high temperature quenching. Finally, the casting is heated to 100℃ in the furnace and kept for 2 hours, then air cooled to complete a low temperature stress relief tempering.

[0058] The impact energy, hardness and wear resistance of the alloy steel prepared by the vanadium-containing low-carbon medium-chromium alloy steel and the preparation process described in this embodiment are shown in Table 1.

[0059] Example 2

[0060] The present embodiment provides a vanadium-containing low-carbon medium-chromium alloy steel, whose chemical composition, by weight percentage, is: Cr4.2%, C 0.25%, V 0.22%, Mn 1.2%, Si 1.35%, Mo 0.56%, Nb 0.05%, P≤0.04%, S≤0.04%, and the balance is iron and inevitable trace elements in the manufacturing process.

[0061] This embodiment also provides a method for preparing vanadium-containing low-carbon medium-chromium alloy steel, comprising the following steps:

[0062] (1) The raw materials used include ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, ferroniobium, ferrovanadium and pig iron.

[0063] (2) Smelting the raw materials and casting them into alloy steel castings. The specific steps are as shown in Example 1.

[0064] (3) After the casting is cooled, heat treatment is performed. Heat from room temperature to 650℃ at a heating rate of 4.5℃ / min and keep it for 2 hours, then heat it to 850℃ at a heating rate of 3.5℃ / min and keep it for 1 hour, and finally heat it to 1045℃ at a heating rate of 8℃ / min and keep it for 3 hours, and then air cool it to complete a homogenization treatment. After the casting is cooled, it is directly heated from room temperature to 795℃ in the furnace and kept for 2 hours, and then oil-cooled. This process is repeated twice to complete two-phase zone quenching. After that, the casting is heated from room temperature to 850℃ in the furnace at a heating rate of 7.5℃ / min and kept for 1.5 hours, and then heated to 1095℃ at a heating rate of 9.5℃ / min and kept for 1.2 hours, and then oil-cooled to complete a high-temperature quenching. Finally, the casting is heated to 150℃ in the furnace and kept for 2 hours, and then air-cooled to complete a low-temperature stress relief tempering.

[0065] The impact energy, hardness and wear resistance of the alloy steel prepared by the vanadium-containing low-carbon medium-chromium alloy steel and the preparation process described in this embodiment are shown in Table 1.

[0066] Example 3

[0067] The present embodiment provides a vanadium-containing low-carbon medium-chromium alloy steel, whose chemical composition, by weight percentage, is: Cr4.15%, C 0.26%, V 0.15%, Mn 1.2%, Si 1.3%, Mo 0.6%, Nb 0.045%, P≤0.04%, S≤0.04%, and the balance is iron and inevitable trace elements in the manufacturing process.

[0068] This embodiment also provides a method for preparing vanadium-containing low-carbon medium-chromium alloy steel, comprising the following steps:

[0069] (1) The raw materials used include ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, ferroniobium, ferrovanadium and pig iron.

[0070] (2) Smelting the raw materials and casting them into alloy steel castings. The specific steps are as shown in Example 1.

[0071] (3) After the casting is cooled, heat treatment is performed. Heat from room temperature to 650℃ at a heating rate of 5℃ / min and keep it for 2 hours, then heat it to 850℃ at a heating rate of 4℃ / min and keep it for 1 hour, and finally heat it to 1060℃ at a heating rate of 9℃ / min and keep it for 2.5 hours, then air cool it to complete a homogenization treatment. After the casting is cooled, it is directly heated from room temperature to 805℃ in the furnace and kept for 2 hours, then oil cooled. This process is repeated twice to complete two-phase zone quenching. After that, the casting is heated from room temperature to 850℃ in the furnace at a heating rate of 8℃ / min and kept for 1.5 hours, then heat it to 1105℃ at a heating rate of 10℃ / min and keep it for 1.5 hours, then oil cooled to complete a high temperature quenching. Finally, the casting is heated to 120℃ in the furnace and kept for 2 hours, then air cooled to complete a low temperature stress relief tempering.

[0072] The impact energy, hardness and wear resistance of the alloy steel prepared by the vanadium-containing low-carbon medium-chromium alloy steel and the preparation process described in this embodiment are shown in Table 1.

[0073] Example 4

[0074] The present embodiment provides a vanadium-containing low-carbon medium-chromium alloy steel, whose chemical composition, by weight percentage, is: Cr4.25%, C 0.25%, V 0.06%, Mn 1.22%, Si 1.36%, Mo 0.55%, Nb 0.04%, P≤0.04%, S≤0.04%, and the balance is iron and inevitable trace elements in the manufacturing process.

[0075] This embodiment also provides a method for preparing vanadium-containing low-carbon medium-chromium alloy steel, comprising the following steps:

[0076] (1) The raw materials used include ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, ferroniobium, ferrovanadium and pig iron.

[0077] (2) Smelting the raw materials and casting them into alloy steel castings. The specific steps are as shown in Example 1.

[0078] (3) After the casting is cooled, heat treatment is performed. Heat from room temperature to 650℃ at a heating rate of 5℃ / min and keep it for 2 hours, then heat it to 850℃ at a heating rate of 3℃ / min and keep it for 1 hour, and finally heat it to 1030℃ at a heating rate of 9℃ / min and keep it for 5 hours, and then air cool it to complete a homogenization treatment. After the casting is cooled, it is directly heated from room temperature to 810℃ in the furnace and kept for 2 hours, and then oil-cooled. This process is repeated twice to complete two-phase zone quenching. After that, the casting is heated from room temperature to 850℃ in the furnace at a heating rate of 7℃ / min and kept for 1.5 hours, and then heated to 1090℃ at a heating rate of 10℃ / min and kept for 1.5 hours, and then oil-cooled to complete a high-temperature quenching. Finally, the casting is heated to 200℃ in the furnace and kept for 1 hour, and then air-cooled to complete a low-temperature stress relief tempering.

[0079] The impact energy, hardness and wear resistance of the alloy steel prepared by the vanadium-containing low-carbon medium-chromium alloy steel and the preparation process described in this embodiment are shown in Table 1.

[0080] Example 5

[0081] The present embodiment provides a vanadium-containing low-carbon medium-chromium alloy steel, whose chemical composition, by weight percentage, is: Cr4.3%, C 0.3%, V 0.03%, Mn 1.25%, Si 1.35%, Mo 0.56%, Nb 0.048%, P≤0.04%, S≤0.04%, and the balance is iron and inevitable trace elements in the manufacturing process.

[0082] This embodiment also provides a method for preparing vanadium-containing low-carbon medium-chromium alloy steel, comprising the following steps:

[0083] (1) The raw materials used include ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, ferroniobium, ferrovanadium and pig iron.

[0084] (2) Smelting the raw materials and casting them into alloy steel castings. The specific steps are as shown in Example 1.

[0085] (3) After the casting is cooled, heat treatment is performed. Heat from room temperature to 650℃ at a heating rate of 4℃ / min and keep it for 2 hours, then heat it to 850℃ at a heating rate of 4℃ / min and keep it for 1 hour, and finally heat it to 1060℃ at a heating rate of 7℃ / min and keep it for 3 hours, and then air cool it to complete a homogenization treatment. After the casting is cooled, it is directly heated from room temperature to 785℃ in the furnace and kept for 2 hours, and then oil-cooled. This process is repeated twice to complete two-phase zone quenching. After that, the casting is heated from room temperature to 850℃ in the furnace at a heating rate of 8℃ / min and kept for 1.5 hours, and then heated to 1100℃ at a heating rate of 9℃ / min and kept for 1 hour, and then oil-cooled to complete a high-temperature quenching. Finally, the casting is heated to 220℃ in the furnace and kept for 1.2 hours, and then air-cooled to complete a low-temperature stress relief tempering.

[0086] The impact energy, hardness and wear resistance of the alloy steel prepared by the vanadium-containing low-carbon medium-chromium alloy steel and the preparation process described in this embodiment are shown in Table 1.

[0087] Comparative Example 1

[0088] This comparative example provides a low-carbon medium-chromium alloy steel, whose chemical composition, in weight percentage, is: Cr 4%, C 0.2%, Mn 1.25%, Si 1.35%, Mo 0.5%, Nb 0.06%, P≤0.04%, S≤0.04%, and the balance is iron and inevitable trace elements in the manufacturing process.

[0089] This comparative example also provides a preparation method of vanadium-containing low-carbon medium-chromium alloy steel, comprising the following steps: first, smelting and casting into alloy steel castings. After the castings are cooled, heat treatment is performed. Slowly heat from room temperature to 650°C and keep warm for 2 hours, then heat to 850°C and keep warm for 1 hour, and finally quickly heat to 1050°C and keep warm for 3.5 hours and then air cool to complete a homogenization treatment; after the castings are cooled, they are directly heated from room temperature to 800°C in the furnace and kept warm for 2 hours and oil cooled, and this process is carried out twice to complete two-phase zone quenching; then the castings are slowly heated from room temperature to 850°C in the furnace and kept warm for 1.5 hours, and then quickly heated to 1100°C and kept warm for 1.2 hours and then oil cooled to complete a high-temperature quenching; finally, the castings are heated to 100°C in the furnace and kept warm for 1.2 hours and then air cooled to complete a low-temperature stress relief tempering.

[0090] The impact energy, hardness and wear resistance of the alloy steel prepared by the vanadium-containing low-carbon medium-chromium alloy steel and the preparation process described in this comparative example are shown in Table 1.

[0091] Comparative Example 2

[0092] This comparative example provides a vanadium-containing low-carbon medium-chromium alloy steel and a preparation method. The chemical composition of the alloy steel is the same as that of Example 1, and the only difference is the heat treatment process. The heat treatment process is different from that of Example 1 only in that: two-phase zone quenching is not performed twice, and the high-temperature quenching process is to heat to 1050°C and keep it for 3 hours and then oil cool.

[0093] The impact energy, hardness and wear resistance of the alloy steel prepared by the vanadium-containing low-carbon medium-chromium alloy steel and the preparation process described in this comparative example are shown in Table 1.

[0094] Comparative Example 3

[0095] This comparative example provides a vanadium-containing low-carbon medium-chromium alloy steel and a preparation method. The chemical composition of the alloy steel is the same as that of Example 5, and the difference lies in the heat treatment process. The difference between the heat treatment process and that of Example 5 is that two-phase zone quenching is not performed twice, and the high-temperature quenching process is to heat to 1060°C and keep warm for 2.5 hours and then cool with oil.

[0096] The impact energy, hardness and wear resistance of the alloy steel prepared by the vanadium-containing low-carbon medium-chromium alloy steel and the preparation process described in this comparative example are shown in Table 1.

[0097] Comparative Example 4

[0098] This comparative example provides a low-carbon medium-chromium alloy steel, whose chemical composition, measured by weight percentage, is: Cr 4.23%, C 0.22%, V 0.5%, Mn 1.26%, Si 1.33%, Mo 0.5%, Nb 0.06%, P≤0.04%, S≤0.04%, and the balance is iron and inevitable trace elements in the manufacturing process.

[0099] This comparative example provides a method for preparing low-carbon medium-chromium alloy steel, and the specific steps refer to Example 1.

[0100] The impact energy, hardness and wear resistance of the alloy steel prepared by the vanadium-containing low-carbon medium-chromium alloy steel and the preparation process described in this comparative example are shown in Table 1.

[0101] Test Example 1

[0102] The properties of the alloy steel prepared in the test examples and comparative examples are shown in Table 1. The wear loss weight test results are shown in Table 1. Figure 1 shown.

[0103] Table 1 Test results of impact energy, hardness and wear loss weight of vanadium-containing low-carbon medium-chromium alloy steel

[0104] Technology Impact energy / J Hardness / HRC Wear loss weight / mg Example 1 60 56 11 Example 2 65 54 18 Example 3 70 55 26 Example 4 52 48 56 Example 5 42 48 64 Comparative Example 1 34 51 75 Comparative Example 2 30 53 96 Comparative Example 3 20 50 105 Comparative Example 4 10 52 114

[0105] It can be seen that the alloy steel prepared in the embodiment of the present application has a larger impact energy and better wear resistance. The comparative example does not introduce vanadium, and it can be seen that the comprehensive performance of the alloy steel is significantly reduced. The comparative examples 2-3 change the heat treatment process, and it can be seen that the comprehensive performance is also significantly reduced.

[0106] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A vanadium-containing low-carbon medium-chromium alloy steel, characterized in that: Its chemical composition, in weight percentage, is: Cr 4.0%~5.0%, C 0.2%~0.3%, V 0.02%~0.4%, Mn 1.1%~1.3%, Si 1.3%~1.4%, Mo 0.5%~0.6%, Nb 0.04%~0.06%, P≤0.04%, S≤0.04%, and the balance is iron and trace elements that are inevitable in the manufacturing process; The method for preparing vanadium-containing low-carbon medium-chromium alloy steel comprises: preparing alloy steel with raw materials prepared according to chemical composition, smelting, casting and heat treating the raw materials; The heat treatment process includes: one homogenization treatment, two two-phase zone quenching, one high-temperature quenching and one low-temperature stress relief tempering; the treatment temperature of the one homogenization treatment is 1030°C~1060°C, the treatment temperature of the two two-phase zone quenching is 780°C~810°C, the treatment temperature of the one high-temperature quenching is 1090°C~1110°C, and the treatment temperature of the one low-temperature stress relief tempering is 100°C~250°C.

2. The vanadium-containing low-carbon medium-chromium alloy steel according to claim 1, characterized in that: Its chemical composition, in weight percentage, is: Cr 4.1%~4.3%, C 0.2%~0.25%, V 0.1%~0.35%, Mn 1.2%~1.25%, Si 1.3%~1.35%, Mo0.5%~0.6%, Nb 0.04%~0.05%, P≤0.04%, S≤0.04%, and the remainder is iron and inevitable trace elements in the manufacturing process.

3. A method for preparing the vanadium-containing low-carbon medium-chromium alloy steel as claimed in claim 1 or 2, characterized in that: include: Alloy steel is prepared from raw materials prepared according to chemical composition, and the raw materials are smelted, cast and heat treated; The heat treatment process includes: one homogenization treatment, two two-phase zone quenching, one high-temperature quenching and one low-temperature stress relief tempering; the treatment temperature of the one homogenization treatment is 1030°C~1060°C, the treatment temperature of the two two-phase zone quenching is 780°C~810°C, the treatment temperature of the one high-temperature quenching is 1090°C~1110°C, and the treatment temperature of the one low-temperature stress relief tempering is 100°C~250°C.

4. The preparation method according to claim 3, characterized in that: The raw materials include ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, ferroniobium, ferrovanadium and pig iron.

5. The preparation method according to claim 3, characterized in that: The smelting and casting process includes: melting the raw materials and adjusting the composition of the molten steel, then deoxidizing and removing impurities from the molten steel, and transferring the molten steel for casting.

6. The preparation method according to claim 3, characterized in that: The process of the primary homogenization treatment includes: firstly heating from room temperature to 600°C~700°C at a heating rate of 4°C / min-5°C / min and keeping warm for 1h-3h, then heating to 800°C~900°C at a heating rate of 3°C / min-4°C / min and keeping warm for 0.5h-1.5h, then heating to 1030°C~1060°C at a heating rate of 7°C / min-9°C / min and keeping warm for 3h-5h, and then air cooling.

7. The preparation method according to claim 3, characterized in that: The two-phase quenching process includes: heating from room temperature to 780° C.-810° C. and keeping the temperature for 1 h-3 h, followed by oil cooling.

8. The preparation method according to claim 3, characterized in that: The process of the primary high-temperature quenching includes: firstly heating from room temperature to 800°C-900°C at a heating rate of 7°C / min-8°C / min and keeping warm for 1.0h-2.0h, then heating to 1090°C-1110°C at a heating rate of 9°C / min-10°C / min and keeping warm for 1.0h-1.5h, and then oil cooling.

9. The preparation method according to claim 3, characterized in that: The process of the primary low-temperature stress relief tempering includes: firstly heating from room temperature to 100°C-220°C at a heating rate of 3°C / min-4°C / min, keeping the temperature for 1.0h-2.0h, and then air cooling.

10. Use of the vanadium-containing low-carbon medium-chromium alloy steel according to any one of claims 1 to 2 or the vanadium-containing low-carbon medium-chromium alloy steel prepared by the preparation method according to any one of claims 3 to 9 in the preparation of wear-resistant components.

11. The use according to claim 10, characterized in that: The wear-resistant component is selected from at least one of a wet ball mill liner, a reamer tooth and a shovel tooth.

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