A low-cost and high-performance alloy cast steel and its preparation method

Abstract

The present invention discloses a low-cost and high-performance alloy cast steel and a preparation method thereof, relating to the technical field of casting. The chemical composition and the weight percentage of the component contents of the alloy cast steel are as follows: carbon 0.30-0.35%, silicon 0.60-0.90%, manganese 1.2-1.5%, phosphorus ≤0.035%, sulfur ≤0.035%, chromium 1.80-2.20%, molybdenum 0.40-0.60%, copper ≤0.20%, nickel 1.60-2.0%, niobium ≤0.02%, the content of residual elements is less than or equal to 0.30%, and the balance is iron. Through the design of the composition and the heat treatment process, the cast steel obtained by the present invention can meet the manufacturing requirements of products such as pump trucks, mixers, and mill accessories that require good wear resistance and high strength performance. Compared with the cast steel material 35Cr2Ni2Mo produced in Germany, the types and amounts of alloys added to the alloy cast steel of the present invention are less, which reduces the production cost of the alloy cast steel, but the mechanical properties remain unchanged, and it has better wear resistance. Therefore, the present invention has the advantages of easy composition control, low production cost, simple smelting process and heat treatment process, small crack tendency, and excellent casting process performance.

Description

Technical Field

[0001] The present invention relates to the field of casting technology, and particularly to an alloy cast steel with low cost and high performance and a preparation method thereof. Background Art

[0002] Large cast steel parts have the characteristics of relatively easy forming and low production cost, so they are widely used in fields such as mines, cement, petroleum, and ships. However, large cast steel parts are prone to defects such as shrinkage porosity, shrinkage cavity, gas holes, and cracks during the forming process, which affect the mechanical properties and service life of large cast steel parts, causing great losses to enterprises and the national economy.

[0003] The cast steel material 35Cr2Ni2Mo that can meet the wear resistance and mechanical property requirements of mixer and coal mill accessories has a high cost. And due to its high carbon content and manganese content, it has poor plasticity and toughness, large crack tendency, and poor weldability; the heat treatment process of 35Cr2Ni2Mo is normalizing plus tempering process. This heat treatment process has high process requirements, complex process operations, large heat treatment deformation and crack tendency of castings, large surface hardness, and complex machining, bringing great inconvenience to actual production. Summary of the Invention

[0004] The purpose of the present invention is to provide an alloy cast steel with low cost and high performance and a preparation method thereof to solve the problems existing in the prior art as mentioned in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] An alloy cast steel with low cost and high performance, the chemical composition and the weight percentage of the component content of the alloy cast steel are as follows:

[0007] Carbon 0.30 - 0.35%, silicon 0.60 - 0.90%, manganese 1.2 - 1.5%, phosphorus ≤ 0.035%, sulfur ≤ 0.035%, chromium 1.80 - 2.20%, molybdenum 0.40 - 0.60%, copper ≤ 0.20%, nickel 1.60 - 2.0%, niobium ≤ 0.02%, the content of residual elements is less than or equal to 0.30%, and the balance is iron.

[0008] A preparation method of an alloy cast steel with low cost and high performance, comprising the following steps:

[0009] S1: Take the raw materials of the alloy cast steel in a certain proportion and melt the alloy cast steel by a conventional melting method;

[0010] S2: Perform full annealing treatment on the melted alloy cast steel;

[0011] S3: Then perform tempering treatment on the alloy cast steel.

[0012] Preferably, the specific steps of annealing the alloy cast steel in S2 are as follows: heat the melted alloy cast steel to 880°C - 920°C, hold for 3 - 4 hours, and cool it to room temperature by blowing air.

[0013] Preferably, the specific steps of tempering the alloy cast steel in S3 are as follows: heat the alloy cast steel to 550°C - 570°C, hold for 3 - 5 hours, and cool it to room temperature naturally.

[0014] An application of a low - cost and high - performance alloy cast steel, which is applied to pump trucks, mixers, and accessories of coal mills.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] Through the design of the composition and heat treatment process, the cast steel obtained by the present invention can meet the manufacturing requirements of products such as pump trucks, mixers, and accessories of coal mills that require good wear resistance and high - strength performance. Compared with the cast steel material 35Cr2Ni2Mo produced in Germany, the types and amounts of alloys added to the alloy cast steel of the present invention are less, which reduces the production cost of the alloy cast steel, but the mechanical properties remain unchanged, and it has better wear resistance. Therefore, the present invention has the advantages of easy composition control, low production cost, simple smelting process and heat treatment process, small crack tendency, and excellent casting process performance, thus being more conducive to industrial application. Brief Description of the Drawings

[0017] Figure 1 Pictures of the metallographic structure of the alloy cast steel of the present invention magnified 100 times and 500 times.

[0018] Figure 2 Pictures of the structure of the alloy cast steel of the present invention scanned and magnified 2000 times and 5000 times.

[0019] Figure 3 A curve graph of the wear performance test results of the alloy cast steel of the present invention and 35Cr2Ni2Mo cast steel. Detailed Embodiments

[0020] To make the technical means, creative features, achieved purposes, and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0021] Please refer to Figures 1-3 , the present invention provides the following technical solutions:

[0022] Example 1

[0023] Take the weight percentages of each chemical component and its content as:

[0024] Carbon 0.33%, silicon 0.77%, manganese 1.49%, phosphorus 0.020%, sulfur 0.015%, chromium 2.04%, molybdenum 0.60%, copper 0.12%, nickel 1.66%, niobium 0.016%, the balance being iron.

[0025] The alloy cast steel is prepared according to the following steps:

[0026] S1: The alloy cast steel is melted by a conventional melting method. The raw materials are melted into molten steel by a steelmaking furnace, and the molten steel is poured into a casting mold to form a casting.

[0027] S2: The alloy cast steel after melting is subjected to full annealing treatment. The specific steps of the annealing treatment of the alloy cast steel are as follows: The alloy cast steel after melting is heated to 900 °C, held for 3.6 hours, and cooled to room temperature by blowing air.

[0028] S3: Then the alloy cast steel is subjected to tempering treatment. The specific steps of the tempering treatment of the alloy cast steel are as follows: The alloy cast steel is heated to 550 °C, held for 5 hours, and cooled to room temperature naturally.

[0029] Table 1 Chemical composition of Example 1 (%), the rest being Fe

[0030]

[0031] The mechanical properties of the alloy cast steel prepared in Example 1 are tested, and the following results are obtained:

[0032] Table 2 Test results of mechanical properties of Example 1

[0033]

[0034] Example 2

[0035] Take the weight percentages of each chemical component and its content as:

[0036] Carbon 0.35%, silicon 0.62%, manganese 1.23%, phosphorus 0.033%, sulfur 0.022%, chromium 1.82%, molybdenum 0.41%, copper 0.20%, nickel 1.96%, niobium 0.019%, the balance being iron.

[0037] The alloy cast steel is prepared according to the following steps:

[0038] S1: The alloy cast steel is melted by a conventional melting method. The raw materials are melted into molten steel by a steelmaking furnace, and the molten steel is poured into a casting mold to form a casting.

[0039] S2: The alloy cast steel after melting is subjected to full annealing treatment. The specific steps of the annealing treatment of the alloy cast steel are as follows: The alloy cast steel after melting is heated to 920 °C, held for 3 hours, and cooled to room temperature by blowing air.

[0040] S3: Then, perform tempering treatment on the alloy cast steel. The specific steps of the tempering treatment of the alloy cast steel are as follows: Heat the alloy cast steel to 565 °C, hold for 3 hours, and then cool it naturally to room temperature.

[0041] Table 3 Chemical composition of Example 2 (%); the balance is Fe

[0042]

[0043] Perform mechanical property tests on the alloy cast steel prepared in Example 2, and the following results are obtained:

[0044] Table 4 Mechanical property test results of Example 2

[0045]

[0046] Example 3

[0047] Take the weight percentages of each chemical component and its content as follows:

[0048] Carbon 0.30%, silicon 0.90%, manganese 1.50%, phosphorus 0.030%, sulfur 0.032%, chromium 2.20%, molybdenum 0.60%, copper 0.15%, nickel 1.60%, niobium 0.020%; the balance is iron.

[0049] Prepare the alloy cast steel according to the following steps:

[0050] S1: Melt the alloy cast steel by using a conventional melting method. Use a steelmaking furnace to melt the raw materials into molten steel, and pour the molten steel into a casting mold to form a casting.

[0051] S2: Perform full annealing treatment on the melted alloy cast steel. The specific steps of the annealing treatment of the alloy cast steel are as follows: Heat the melted alloy cast steel to 880 °C, hold for 4 hours, and cool it to room temperature by blowing air.

[0052] S3: Then, perform tempering treatment on the alloy cast steel. The specific steps of the tempering treatment of the alloy cast steel are as follows: Heat the alloy cast steel to 570 °C, hold for 4.1 hours, and then cool it naturally to room temperature.

[0053] Table 5 Chemical composition of Example 3 (%); the balance is Fe

[0054]

[0055] Perform mechanical property tests on the alloy cast steel prepared in Example 3, and the following results are obtained:

[0056] Table 6 Mechanical property test results of Example 3

[0057]

[0058] According to the above mechanical property test results, it can be obtained that the mechanical properties of the alloy cast steel of the present invention are as follows: the tensile strength ≥ 1200 MPa, the yield strength ≥ 860 MPa, the elongation ≥ 7%, and the Vickers hardness value ≥ 500 HV, meeting the requirements of the mechanical properties of cast steel for liners, mixing arm fittings, pump truck fittings, and coal mill fittings; the wear resistance test was carried out on the alloy cast steel of Example 3 in the present invention and the German 35Cr2Ni2Mo cast steel, and the test results are as Figure 3 shown. Under the same friction conditions and time, the wear amount of the alloy cast steel of the present invention is smaller, having better wear resistance.

[0059] Compared with the chemical composition of the 35Cr2Ni2Mo cast steel material produced in Germany, the amount and types of alloys added to the alloy cast steel in the present invention are less, and the addition amount of the precious metal element Mo is appropriately reduced, making the alloy cost about 300 yuan / ton of steel lower than that of 35Cr2Ni2Mo, and the mechanical properties remain unchanged. Therefore, the present invention has the advantages of easy composition control, low production cost, simple smelting process and heat treatment process, small crack tendency, and excellent casting process performance, thus being more conducive to industrial application.

[0060] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-cost and high-performance alloy cast steel, characterized in that, The chemical composition and weight percentage of the alloy cast steel are as follows: Carbon 0.30 - 0.35%, silicon 0.60 - 0.62%, manganese 1.2 - 1.5%, 0.033 ≤ phosphorus ≤ 0.035%, sulfur ≤ 0.035%, chromium 1.80 - 1.82%, molybdenum 0.40 - 0.41%, copper ≤ 0.20%, nickel 1.60 - 2.0%, niobium ≤ 0.02%, the content of residual elements is less than or equal to 0.30%, and the balance is iron; The preparation method of the alloy cast steel includes the following steps: S1: Take the raw materials of the alloy cast steel in a certain proportion and melt the alloy cast steel by a conventional melting method; S2: Conduct a full annealing treatment on the melted alloy cast steel; S3: Then conduct a tempering treatment on the alloy cast steel; The specific steps of the annealing treatment of the alloy cast steel in S2 are: heat the melted alloy cast steel to 880°C - 920°C, keep it warm for 3 - 4 hours, and blow air to cool it to room temperature; The specific steps of the tempering treatment of the alloy cast steel in S3 are: heat the alloy cast steel to 550°C - 570°C, keep it warm for 3 - 5 hours, and naturally cool it to room temperature.

2. Application of a low-cost and high-performance alloy cast steel, characterized in that, Apply the alloy cast steel in Claim 1 to the accessories of concrete pumps, mixers, and coal mill.

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