High-strength gear steel and preparation method thereof

Abstract

The invention relates to the technical field of gear steel, and provides high-strength gear steel and a preparation method thereof.The gear steel comprises a base body and a reinforcing phase, and the base body is composed of, by weight, 0.13%-0.22% of C, 0.3%-1.2% of Mn, 0.15%-0.675% of Nb, 1.4%-2.4% of Cr, 0.1%-0.3% of Ni, 0.2%-0.5% of Zr, smaller than or equal to 0.05% of P, smaller than or equal to 0.05% of S and the balance Fe and inevitable impurities; the reinforcing phase is tungsten trioxide, and the weight ratio of the matrix to the reinforcing phase is 100: (1-4). By means of the technical scheme, the problem that in the related technology, the strength of gear steel is low is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of gear steel, and in particular to a high-strength gear steel and a preparation method thereof. Background Art

[0002] In today's modern industrial field, gears, as a kind of vital mechanical transmission elements, are widely used in many fields such as automobiles, aerospace, engineering machinery, machine tools, etc. The performance of the gear itself will directly affect the reliability, efficiency and service life of the entire mechanical system. Traditional gear steel can certainly meet some needs to a certain extent. However, when faced with increasingly complex and harsh working conditions, some shortcomings are often exposed. Among these shortcomings, the most significant impact is strength. As far as the current situation is concerned, the strength of existing gear steel is relatively low. In view of this, there is an urgent need to develop a high-strength gear steel to improve the operating performance and reliability of gears under various complex working conditions and ensure the stable operation of mechanical systems in complex working environments. Summary of the invention

[0003] The present invention provides a high-strength gear steel and a preparation method thereof, which solves the problem of low strength of gear steel in the related art.

[0004] The technical solution of the present invention is as follows: The present invention provides a high-strength gear steel, comprising a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following components in weight percentage: C 0.13%-0.22%, Mn 0.3%-1.2%, Nb 0.15%-0.675%, Cr 1.4%-2.4%, Ni 0.1%-0.3%, Zr 0.2%-0.5%, P≤0.05%, S≤0.05%, and the rest is Fe and inevitable impurities; the reinforcement phase is tungsten trioxide, and the weight ratio of the matrix to the reinforcement phase is 100:1-4.

[0005] As a further technical solution, the ratio of the sum of the weights of the Mn and Nb to the weight of the Cr is 1≤(2Mn+4Nb) / Cr≤2.

[0006] In the present invention, when the weight ratio of the sum of the weights of Mn and Nb to the weight of Cr is 1≤(2Mn+4Nb) / Cr≤2, it helps to further improve the strength of the gear steel.

[0007] As a further technical solution, the weight ratio of the Mn to the Nb is Mn / Nb<2.

[0008] In the present invention, when the weight ratio of the sum of Mn and Nb to Cr is 1≤(2Mn+4Nb) / Cr≤2 and the weight ratio of Mn to Nb is Mn / Nb<2, it helps to further improve the strength of the gear steel.

[0009] As a further technical solution, the median particle size of the tungsten trioxide is 10-40 μm.

[0010] As a further technical solution, the tungsten trioxide is modified tungsten trioxide, and the raw materials of the modified tungsten trioxide include carbon powder and tungsten trioxide.

[0011] In the present invention, the inventors found that the strength of gear steel can be further improved by modifying tungsten trioxide with carbon powder. It is speculated that this is because compared with tungsten trioxide, the modification of tungsten trioxide with carbon powder can improve the wettability of the reinforcement phase to the steel liquid, thereby further improving the interface bonding between the reinforcement phase and the matrix, and further improving the strength of the gear steel.

[0012] As a further technical solution, the median particle size of the carbon powder is 50-100 nm.

[0013] As a further technical solution, the weight ratio of the carbon powder to tungsten trioxide is 2~4:100.

[0014] In the present invention, when the weight ratio of carbon powder to tungsten trioxide is 2-4:100, it helps to further improve the strength of the gear steel.

[0015] As a further technical solution, the preparation method of the modified tungsten trioxide includes the following steps: mixing carbon powder and tungsten trioxide evenly, hot pressing and sintering, and crushing to obtain the modified tungsten trioxide.

[0016] As a further technical solution, during the hot pressing sintering, the temperature is 1300-1400° C., the pressure is 20-30 MPa, and the time is 1-2 hours.

[0017] The present invention also proposes a method for preparing the high-strength gear steel, comprising the following steps: S1, mixing materials according to the weight percentage of the matrix, smelting, and obtaining molten steel; S2, adding a reinforcing phase into the molten steel, stirring, and casting to obtain a billet; S3. After rolling, finishing and heat treatment, the blank is obtained to obtain gear steel.

[0018] As a further technical solution, in step S3, the heat treatment is performed at a temperature of 500-600°C and for a time of 1-2 hours.

[0019] In the present invention, the internal residual stress and segregation of the gear steel can be eliminated by heat treatment, so that the internal structure of the gear steel can reach the best.

[0020] The working principle and beneficial effects of the present invention are: In the present invention, the gear steel has a higher strength by optimizing the component composition of the matrix and introducing the tungsten trioxide reinforcement phase. Among them, the strength of the gear steel is improved by the combination of the three elements of Mn, Nb and Cr. In addition, the addition of the tungsten trioxide reinforcement phase can play a pinning role, improve the ability of the gear steel to resist external forces, and thus improve the strength of the gear steel. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the following embodiments and comparative examples, unless otherwise specified, the manganese content in ferromanganese is 75.3wt%; the niobium content in ferroniobium is 62.5wt%; the zirconium content in ferrozirconium is 60wt%; the nickel content in ferronickel is 70.3wt%; the chromium content in ferrochrome is 55wt%; the iron content in scrap steel is 97.6wt%; the median particle size of tungsten trioxide is 25μm; and the median particle size of carbon powder is 75nm.

[0023] Example 1 A high-strength gear steel comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following components in weight percentage: C 0.13%, Mn 0.3%, Nb 0.15%, Cr 1.4%, Ni 0.1%, Zr 0.2%, P 0.05%, S 0.05%, and the remainder is Fe and inevitable impurities, the reinforcement phase is tungsten trioxide, and the weight ratio of the reinforcement phase to the matrix is ​​1:100; The preparation method thereof comprises the following steps: S1. Weigh ferromanganese, ferroniobium, ferrozirconium, ferronickel, ferrochrome and scrap steel according to the target weight percentage of the components of the matrix, and smelt them to obtain molten steel; S2, adding a reinforcing phase into the molten steel, stirring, and casting to obtain a billet; S3. After rolling, finishing and heat treatment at 500°C for 2h, the billet is obtained as gear steel.

[0024] Example 2 A high-strength gear steel comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following components in weight percentage: C 0.22%, Mn 1.2%, Nb 0.675%, Cr 2.4%, Ni 0.3%, Zr 0.5%, P 0.03%, S 0.03%, and the remainder is Fe and inevitable impurities, the reinforcement phase is tungsten trioxide, and the weight ratio of the reinforcement phase to the matrix is ​​4:100; The preparation method thereof comprises the following steps: S1. Weigh ferromanganese, ferroniobium, ferrozirconium, ferronickel, ferrochrome and scrap steel according to the target weight percentage of the components of the matrix, and smelt them to obtain molten steel; S2, adding a reinforcing phase into the molten steel, stirring, and casting to obtain a billet; S3. After the billet is rolled and heat treated at 600°C for 1 hour, gear steel is obtained.

[0025] Example 3 A high-strength gear steel comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following components in weight percentage: C 0.16%, Mn 0.45%, Nb 0.3%, Cr 2.4%, Ni 0.2%, Zr 0.4%, P 0.01%, S 0.01%, and the remainder is Fe and inevitable impurities, the reinforcement phase is tungsten trioxide, and the weight ratio of the reinforcement phase to the matrix is ​​4:100; The preparation method thereof comprises the following steps: S1. Weigh ferromanganese, ferroniobium, ferrozirconium, ferronickel, ferrochrome and scrap steel according to the target weight percentage of the components of the matrix, and smelt them to obtain molten steel; S2, adding a reinforcing phase into the molten steel, stirring, and casting to obtain a billet; S3. After rolling, the billet is heat treated at 550°C for 1.5h to obtain gear steel.

[0026] Example 4 The only difference between this embodiment and embodiment 3 is that, in this embodiment, the matrix is ​​composed of the following components in weight percentage: C 0.16%, Mn 0.675%, Nb 0.4375%, Cr 1.4%, Ni 0.2%, Zr 0.4%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities.

[0027] Example 5 The only difference between this embodiment and embodiment 3 is that, in this embodiment, the matrix is ​​composed of the following components in weight percentage: C 0.16%, Mn 0.5%, Nb 0.3125%, Cr 2.25%, Ni 0.2%, Zr 0.4%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities.

[0028] Example 6 The only difference between this embodiment and embodiment 3 is that, in this embodiment, the matrix is ​​composed of the following components in weight percentage: C 0.16%, Mn 1%, Nb 0.25%, Cr 1.5%, Ni 0.2%, Zr 0.4%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities.

[0029] Example 7 The only difference between this embodiment and embodiment 3 is that, in this embodiment, the matrix is ​​composed of the following components in weight percentage: C 0.16%, Mn 0.75%, Nb 0.375%, Cr 1.5%, Ni 0.2%, Zr 0.4%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities.

[0030] Example 8 The only difference between this embodiment and embodiment 3 is that, in this embodiment, the matrix is ​​composed of the following components in weight percentage: C 0.16%, Mn 0.5%, Nb 0.5%, Cr 1.5%, Ni 0.2%, Zr 0.4%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities.

[0031] Example 9 The difference between this embodiment and embodiment 8 is that in this embodiment, the reinforcing phase is modified tungsten trioxide. The preparation method of modified tungsten trioxide includes the following steps: mixing carbon powder and tungsten trioxide evenly, hot pressing and sintering at 1350°C and 25MPa for 1.5h, and crushing to obtain modified tungsten trioxide with a median particle size of 25μm; Wherein, the weight ratio of carbon powder to tungsten trioxide is 0.5:100.

[0032] Example 10 The only difference between this embodiment and embodiment 9 is that in this embodiment, the weight ratio of carbon powder to tungsten trioxide is 8:100.

[0033] Embodiment 11 The only difference between this embodiment and embodiment 9 is that in this embodiment, the weight ratio of carbon powder to tungsten trioxide is 2:100.

[0034] Example 12 The only difference between this embodiment and embodiment 9 is that, in this embodiment, the weight ratio of carbon powder to tungsten trioxide is 4:100.

[0035] Comparative Example 1 The only difference between this comparative example and Example 1 is that, in this comparative example, the matrix consists of the following components in weight percentage: C 0.13%, Mn 0.3%, Cr 1.4%, Ni 0.1%, Zr 0.2%, P 0.05%, S 0.05%, and the rest is Fe and inevitable impurities.

[0036] Comparative Example 2 The only difference between this comparative example and Example 1 is that, in this comparative example, the matrix consists of the following components in weight percentage: C 0.13%, Nb 0.15%, Cr 1.4%, Ni 0.1%, Zr 0.2%, P 0.05%, S 0.05%, and the rest is Fe and inevitable impurities.

[0037] Comparative Example 3 The only difference between this comparative example and Example 1 is that, in this comparative example, the matrix consists of the following components in weight percentage: C 0.13%, Mn 0.3%, Nb 0.15%, Ni 0.1%, Zr 0.2%, P 0.05%, S 0.05%, and the rest is Fe and inevitable impurities.

[0038] Comparative Example 4 The only difference between this comparative example and Example 1 is that, in this comparative example, the matrix consists of the following components in weight percentage: C 0.13%, Cr 1.4%, Ni 0.1%, Zr 0.2%, P 0.05%, S 0.05%, and the rest is Fe and inevitable impurities.

[0039] Comparative Example 5 The only difference between this comparative example and Example 1 is that in this comparative example, no tungsten trioxide reinforcement phase is added.

[0040] The tensile strength and yield strength of the gear steels prepared in Examples 1 to 12 and Comparative Examples 1 to 5 were tested using a GL2000 microcomputer-controlled electro-hydraulic servo universal testing machine, wherein the test rate was 0.006 s -1 The final result was the average of the three samples in each group.

[0041] The test results are shown in Table 1 below.

[0042] Table 1 Test results of tensile strength and yield strength

[0043] The comparison between Example 1 and Comparative Examples 1 to 4 shows that the combination of Mn, Nb and Cr can jointly improve the strength of gear steel. The comparison between Example 1 and Comparative Example 5 shows that the addition of tungsten trioxide reinforcement phase can significantly improve the strength of gear steel.

[0044] Comparison between Examples 3-4 and 5-8 shows that when the weight ratio of Mn and Nb to the weight of Cr is 1≤(2Mn+4Nb) / Cr≤2, it helps to further improve the strength of the gear steel. Comparison between Example 8 and Examples 6-7 shows that when the weight ratio of Mn and Nb to the weight of Cr is 1≤(2Mn+4Nb) / Cr≤2 and the weight ratio of Mn to Nb is Mn / Nb<2, it helps to further improve the strength of the gear steel.

[0045] The comparison between Example 8 and Examples 9 to 12 shows that the strength of the gear steel can be further improved by modifying tungsten trioxide with carbon powder. The comparison between Examples 9 to 10 and Examples 11 to 12 shows that when the weight ratio of carbon powder to tungsten trioxide is 2 to 4:100, it helps to further improve the strength of the gear steel.

[0046] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-strength gear steel, characterized in that: The invention comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following components in weight percentage: C 0.13%-0.22%, Mn 0.3%-1.2%, Nb 0.15%-0.675%, Cr 1.4%-2.4%, Ni 0.1%-0.3%, Zr 0.2%-0.5%, P≤0.05%, S≤0.05%, and the rest is Fe and inevitable impurities; the reinforcement phase is tungsten trioxide, and the weight ratio of the matrix to the reinforcement phase is 100:1-4.

2. The high-strength gear steel according to claim 1, characterized in that: The ratio of the sum of the weights of the Mn and Nb to the weight of the Cr is 1≤(2Mn+4Nb) / Cr≤2.

3. The high-strength gear steel according to claim 2, characterized in that: The weight ratio of the Mn to the Nb is Mn / Nb<2.

4. The high-strength gear steel according to claim 1, characterized in that: The median particle size of the tungsten trioxide is 10-40 μm.

5. The high-strength gear steel according to claim 1, characterized in that: The tungsten trioxide is modified tungsten trioxide, and the raw materials of the modified tungsten trioxide include carbon powder and tungsten trioxide.

6. The high-strength gear steel according to claim 5, characterized in that: The weight ratio of the carbon powder to tungsten trioxide is 2-4:

100.

7. The high-strength gear steel according to claim 5, characterized in that: The preparation method of the modified tungsten trioxide comprises the following steps: mixing carbon powder and tungsten trioxide evenly, hot pressing and sintering, and crushing to obtain the modified tungsten trioxide.

8. The high-strength gear steel according to claim 7, characterized in that: During the hot pressing sintering, the temperature is 1300-1400° C., the pressure is 20-30 MPa, and the time is 1-2 hours.

9. A method for preparing high-strength gear steel according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, mixing materials according to the weight percentage of the matrix, smelting, and obtaining molten steel; S2, adding a reinforcing phase into the molten steel, stirring, and casting to obtain a billet; S3. After rolling, finishing and heat treatment, the blank is obtained to obtain gear steel.

10. The method for preparing high-strength gear steel according to claim 9, characterized in that: In step S3, during the heat treatment, the temperature is 500-600° C. and the time is 1-2 hours.

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