A high-strength bolt

Abstract

The present invention relates to the technical field of fasteners, and provides a high-strength bolt. The bolt is processed from a blank, and the blank includes a matrix and a reinforcing phase. The matrix is composed of the following components by weight percentage: C 0.13% - 0.22%, Mn 0.6% - 2.4%, V 0.6% - 2.7%, Zr 1.4% - 2.4%, Ni 0.1% - 0.3%, Cr 0.2% - 0.5%, P ≤ 0.01%, S ≤ 0.01%, and the balance is Fe and inevitable impurities; the reinforcing phase is molybdenum nitride, and the weight ratio of the matrix to the reinforcing phase is 100:2 - 6. Through the above technical solution, the problem of low bolt strength in the related art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fasteners, and specifically, to a high-strength bolt. Background Art

[0002] As a key connecting element, bolts play a crucial role in many engineering application fields, such as large bridges, high-rise buildings, and heavy machinery. The strength performance of bolts directly relates to the reliability and stability of the connection structure. With the continuous development of industry, the strength requirements for bolts in engineering applications are becoming increasingly stringent.

[0003] Traditional ordinary bolts gradually expose their limitations in high-load, high-vibration, and high-safety-requirement scenarios, and their strength often fails to meet the connection requirements under complex working conditions. In view of this situation, to further expand the service range of bolts, it is of great significance to develop a high-strength bolt. Summary of the Invention

[0004] The present invention provides a high-strength bolt, which solves the problem of low bolt strength in the related art.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a high-strength bolt, which is processed from a blank. The blank includes a matrix and a reinforcing phase. The matrix is composed of the following components by weight percentage: C 0.13% - 0.22%, Mn 0.6% - 2.4%, V 0.6% - 2.7%, Zr 1.4% - 2.4%, Ni 0.1% - 0.3%, Cr 0.2% - 0.5%, P≤0.01%, S≤0.01%, and the rest is Fe and inevitable impurities; the reinforcing phase is molybdenum nitride, and the weight ratio of the matrix to the reinforcing phase is 100:2 - 6.

[0007] As a further technical solution, the weight ratio of the sum of the weights of Mn and V to the weight of Zr is 1≤(Mn + V) / Zr≤2.

[0008] In the present invention, when the weight ratio of the sum of the weights of Mn and V to the weight of Zr is 1≤(Mn + V) / Zr≤2, it helps to further improve the strength of the bolt.

[0009] As a further technical solution, the weight of Mn is less than the weight of V.

[0010] In the present invention, when the weight ratio of the sum of the weights of Mn and V to the weight of Zr is 1≤(Mn + V) / Zr≤2 and the weight of Mn is less than the weight of V, it helps to further improve the strength of the bolt.

[0011] As a further technical solution, the average particle size of the molybdenum nitride is 20-50 μm.

[0012] As a further technical solution, the molybdenum nitride is titanium-doped molybdenum nitride, and the raw materials of the titanium-doped molybdenum nitride include titanium powder and molybdenum nitride.

[0013] In the present invention, although adding molybdenum nitride to the matrix in the form of a reinforcing phase can improve the strength of the bolt to a certain extent, the inventor found that doping titanium in the molybdenum nitride can further improve the strength of the bolt. It is speculated that this is because the wettability of titanium-doped molybdenum nitride with the molten steel is better than that of molybdenum nitride.

[0014] As a further technical solution, the average particle size of the titanium powder is 50-100 nm.

[0015] As a further technical solution, the weight ratio of the titanium powder to the molybdenum nitride is 1:20-30.

[0016] In the present invention, when the weight ratio of the titanium powder to the molybdenum nitride is 1:20-30, it is helpful to further improve the strength of the bolt.

[0017] As a further technical solution, the preparation method of the titanium-doped molybdenum nitride includes the following steps: mixing the titanium powder and the molybdenum nitride evenly, hot pressing and sintering, and pulverizing to obtain the titanium-doped molybdenum nitride.

[0018] As a further technical solution, during the hot pressing and sintering, the temperature is 1000-1200 °C, the pressure is 20-30 MPa, and the time is 2-4 h.

[0019] The present invention also provides a preparation method of the high-strength bolt, including the following steps:

[0020] S1. Weigh the components according to the weight percentage of the matrix, melt them to obtain molten steel;

[0021] S2. Put the reinforcing phase into the molten steel, mix and cast to obtain a blank;

[0022] S3. After descaling, cold heading, thread machining and heat treatment of the blank, a bolt is obtained.

[0023] As a further technical solution, in step S3, during the heat treatment, the temperature is 300-350 °C, and the time is 1-2 h.

[0024] In the present invention, the residual stress after cold working of the bolt can be eliminated through heat treatment, so that the internal tissue form of the bolt reaches the best state.

[0025] The working principle and beneficial effects of the present invention are as follows:

[0026] In the present invention, on the one hand, the component composition of the matrix is optimized, and on the other hand, a molybdenum nitride reinforcing phase is introduced, so that the bolt has high strength. Among them, through the complementary advantages of Mn, V and Zr, the strength of the bolt is jointly improved. In addition, the addition of the molybdenum nitride reinforcing phase can play a role in pinning the second-phase particles, improving the ability of the bolt to resist external forces, thereby improving the strength of the bolt. Specific Embodiments

[0027] The following will combine 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 a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0028] In the following embodiments and comparative examples, unless otherwise specified, the manganese content in ferromanganese is 75.3 wt%; the vanadium content in ferrovanadium is 62.5 wt%; the zirconium content in ferrozirconium is 60 wt%; the nickel content in ferronickel is 70.3 wt%; the chromium content in ferrochrome is 55 wt%; the iron content in scrap iron is 97.6 wt%; the average particle size of molybdenum nitride is 45 μm; the average particle size of titanium powder is 50 nm.

[0029] Example 1

[0030] A high-strength bolt is processed from a blank. The blank includes a matrix and a reinforcing phase. The matrix is composed of the following components by weight percentage: C 0.13%, Mn 0.6%, V 0.6%, Zr 1.4%, Ni 0.1%, Cr 0.2%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities. The reinforcing phase is molybdenum nitride, and the weight ratio of the reinforcing phase to the matrix is 2:100;

[0031] Its preparation method includes the following steps:

[0032] S1. Weigh ferromanganese, ferrovanadium, ferrozirconium, ferronickel, ferrochrome and scrap steel according to the target weight percentage of the components of the matrix, melt them to obtain molten steel;

[0033] S2. Add the reinforcing phase into the molten steel, mix and cast to obtain a blank;

[0034] S3. After the blank is descaled, cold upset, thread processed and heat treated at 300 °C for 2 h, a bolt is obtained.

[0035] Example 2

[0036] A high-strength bolt is processed from a blank. The blank includes a matrix and a reinforcing phase. The matrix is composed of the following components by weight percentage: C 0.22%, Mn 2.4%, V 2.7%, Zr 2.4%, Ni 0.3%, Cr 0.5%, P 0.005%, S 0.005%, and the balance is Fe and unavoidable impurities. The reinforcing phase is molybdenum nitride, and the weight ratio of the reinforcing phase to the matrix is 4:100;

[0037] Its preparation method includes the following steps:

[0038] S1. Weigh ferromanganese, ferrovanadium, ferrozirconium, ferronickel, ferrochrome and scrap steel according to the target weight percentages of the components of the matrix, melt them to obtain molten steel;

[0039] S2. Put the reinforcing phase into the molten steel, mix and cast to obtain a blank;

[0040] S3. After the blank is descaled, cold upset, thread processed and heat treated at 350°C for 1 h, a bolt is obtained.

[0041] Example 3

[0042] A high-strength bolt is processed from a blank. The blank includes a matrix and a reinforcing phase. The matrix is composed of the following components by weight percentage: C 0.16%, Mn 0.9%, V 1.2%, Zr 2.4%, Ni 0.2%, Cr 0.4%, P 0.005%, S 0.005%, and the balance is Fe and unavoidable impurities. The reinforcing phase is molybdenum nitride, and the weight ratio of the reinforcing phase to the matrix is 6:100;

[0043] Its preparation method includes the following steps:

[0044] S1. Weigh ferromanganese, ferrovanadium, ferrozirconium, ferronickel, ferrochrome and scrap steel according to the target weight percentages of the components of the matrix, melt them to obtain molten steel;

[0045] S2. Put the reinforcing phase into the molten steel, mix and cast to obtain a blank;

[0046] S3. After the blank is descaled, cold upset, thread processed and heat treated at 350°C for 1 h, a bolt is obtained.

[0047] Example 4

[0048] The difference between this example and Example 3 is only that in this example, the matrix is composed of the following components by weight percentage: C 0.16%, Mn 1.35%, V 1.75%, Zr 1.4%, Ni 0.2%, Cr 0.4%, P 0.005%, S 0.005%, and the balance is Fe and unavoidable impurities.

[0049] Example 5

[0050] The difference between this embodiment and Embodiment 3 is only that in this embodiment, the matrix is composed of the following components by weight percentage: C 0.16%, Mn 1%, V 1.25%, Zr 2.25%, Ni 0.2%, Cr 0.4%, P 0.005%, S 0.005%, and the rest is Fe and inevitable impurities.

[0051] Embodiment 6

[0052] The difference between this embodiment and Embodiment 3 is only that in this embodiment, the matrix is composed of the following components by weight percentage: C 0.16%, Mn 2%, V 1%, Zr 1.5%, Ni 0.2%, Cr 0.4%, P 0.005%, S 0.005%, and the rest is Fe and inevitable impurities.

[0053] Embodiment 7

[0054] The difference between this embodiment and Embodiment 3 is only that in this embodiment, the matrix is composed of the following components by weight percentage: C 0.16%, Mn 1.5%, V 1.5%, Zr 1.5%, Ni 0.2%, Cr 0.4%, P 0.005%, S 0.005%, and the rest is Fe and inevitable impurities.

[0055] Embodiment 8

[0056] The difference between this embodiment and Embodiment 3 is only that in this embodiment, the matrix is composed of the following components by weight percentage: C 0.16%, Mn 1%, V 2%, Zr 1.5%, Ni 0.2%, Cr 0.4%, P 0.005%, S 0.005%, and the rest is Fe and inevitable impurities.

[0057] Embodiment 9

[0058] The difference between this embodiment and Embodiment 8 is only that in this embodiment, the reinforcing phase is titanium-doped molybdenum nitride, and the preparation method of titanium-doped molybdenum nitride includes the following steps: mixing titanium powder and molybdenum nitride evenly, hot-pressing and sintering at 1100 °C and 25 MPa for 3 h, and pulverizing to obtain titanium-doped molybdenum nitride with an average particle size of 45 μm;

[0059] Among them, the weight ratio of titanium powder to molybdenum nitride is 1:15.

[0060] Embodiment 10

[0061] The difference between this embodiment and Embodiment 9 is only that in this embodiment, the weight ratio of titanium powder to molybdenum nitride is 1:35.

[0062] Embodiment 11

[0063] The difference between this embodiment and Embodiment 9 is only that, in this embodiment, the weight ratio of titanium powder to molybdenum nitride is 1:20.

[0064] Embodiment 12

[0065] The difference between this embodiment and Embodiment 9 is only that, in this embodiment, the weight ratio of titanium powder to molybdenum nitride is 1:30.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, the matrix is composed of the following components by weight percentage: C 0.13%, Mn 1.2%, Zr 1.4%, Ni 0.1%, Cr 0.2%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, the matrix is composed of the following components by weight percentage: C 0.13%, V 1.2%, Zr 1.4%, Ni 0.1%, Cr 0.2%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, the matrix is composed of the following components by weight percentage: C 0.13%, Mn 1.3%, V 1.3%, Ni 0.1%, Cr 0.2%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, the matrix is composed of the following components by weight percentage: C 0.13%, Zr 2.6%, Ni 0.1%, Cr 0.2%, P 0.01%, S 0.01%, and the rest is Fe and inevitable impurities.

[0074] Comparative Example 5

[0075] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, the molybdenum nitride reinforcing phase is not added.

[0076] Use a GL2000 microcomputer-controlled electro-hydraulic servo universal testing machine to test the tensile strength and yield strength of the bolts prepared in Embodiments 1 to 12 and Comparative Examples 1 to 5. Among them, the test rate is 0.006 s -1, the average value of the results of three specimens in each group is used as the final result.

[0077] The test results are shown in Table 1 below.

[0078] Table 1 Test Results of Tensile Strength and Yield Strength

[0079]

[0080] The comparison between Example 1 and Comparative Examples 1-4 shows that through the complementary advantages of Mn, V, and Zr, the strength of the bolt can be jointly improved. The comparison between Example 1 and Comparative Example 5 shows that the addition of molybdenum nitride reinforcing phase can significantly improve the strength of the bolt.

[0081] The comparison between Examples 3-4 and Examples 5-8 shows that when the weight ratio of the sum of Mn and V to Zr is 1 ≤ (Mn + V) / Zr ≤ 2, it helps to further improve the strength of the bolt. The comparison between Example 8 and Examples 6-7 shows that when the weight ratio of the sum of Mn and V to Zr is 1 ≤ (Mn + V) / Zr ≤ 2 and the weight of Mn is less than the weight of V, it helps to further improve the strength of the bolt.

[0082] The comparison between Example 8 and Examples 9-12 shows that the strength of the bolt can be further improved by doping titanium in molybdenum nitride. The comparison between Examples 9-10 and Examples 11-12 shows that when the weight ratio of titanium powder to molybdenum nitride is 1:20-30, it helps to further improve the strength of the bolt.

[0083] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-strength bolt, which is processed from a blank, characterized in that, The blank includes a matrix and a reinforcing phase. The matrix is composed of the following components by weight percentage: C 0.13% - 0.22%, Mn 0.6% - 2.4%, V 0.6% - 2.7%, Zr 1.4% - 2.4%, Ni 0.1% - 0.3%, Cr 0.2% - 0.5%, P ≤ 0.01%, S ≤ 0.01%, and the balance is Fe and inevitable impurities; the reinforcing phase is molybdenum nitride, and the weight ratio of the matrix to the reinforcing phase is 100:2 - 6; The weight ratio of the sum of the weights of Mn and V to the weight of Zr is 1 ≤ (Mn + V) / Zr ≤ 2; The molybdenum nitride is titanium-doped molybdenum nitride, and the raw materials of the titanium-doped molybdenum nitride include titanium powder and molybdenum nitride; The weight ratio of the titanium powder to the molybdenum nitride is 1:20 - 30; The preparation method of the high-strength bolt includes the following steps: S1. Weigh materials according to the weight percentage composition of the matrix, melt them to obtain molten steel; S2. Put the reinforcing phase into the molten steel, mix them, and cast to obtain a blank; S3. After descaling, cold heading, thread machining, and heat treatment of the blank, a bolt is obtained.

2. The high-strength bolt according to claim 1, characterized in that, The weight of Mn is less than the weight of V.

3. A high-strength bolt according to claim 1, characterized in that, The average particle size of the molybdenum nitride is 20 - 50 μm.

4. A high-strength bolt according to claim 1, characterized in that, The preparation method of the titanium-doped molybdenum nitride includes the following steps: Mix the titanium powder and molybdenum nitride evenly, perform hot press sintering, and pulverize to obtain the titanium-doped molybdenum nitride.

5. A high-strength bolt according to claim 4, characterized in that, During the hot press sintering, the temperature is 1000 - 1200 °C, the pressure is 20 - 30 MPa, and the time is 2 - 4 h.

6. A preparation method of a high-strength bolt according to any one of claims 1 to 5, characterized in that, It includes the following steps: S1. Weigh materials according to the weight percentage composition of the matrix, melt them to obtain molten steel; S2. Put the reinforcing phase into the molten steel, mix them, and cast to obtain a blank; S3. After descaling, cold heading, thread machining, and heat treatment of the blank, a bolt is obtained.

7. The preparation method of a high-strength bolt according to claim 6, characterized in that, In step S3, during the heat treatment, the temperature is 300 - 350 °C, and the time is 1 - 2 h.

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