CN111118406B - A kind of manufacturing method of high-strength bolts resistant to marine atmospheric corrosion - Google Patents

Abstract

The invention discloses a marine atmospheric corrosion resistant high-strength bolt which comprises the following components in percentage by mass: 0.10 to 0.40; si: 0.10 to 0.60; mn: 0.30 to 1.20; p is less than or equal to 0.025; s is less than or equal to 0.01; ni: 3.0 to 3.5; cu: 0.20 to 0.70; mo: 0.10 to 0.65; v: less than or equal to 0.10; ti: 0.02-0.10: b: 0.001 to 0.003; nb: 0.04 to 0.10; als is more than or equal to 0.015; n: 0.009-0.018; w: 0.1 to 0.8; zr: 0.015 to 0.045. The invention also discloses a manufacturing method of the marine atmospheric corrosion resistant high-strength bolt. The tensile strength of the bolt manufactured by the method is 1075-1200 MPa, and the bolt has an excellent marine atmosphere corrosion resistance.

Description

A kind of manufacturing method of high-strength bolts resistant to marine atmospheric corrosion

technical field

The invention relates to a marine atmospheric corrosion-resistant high-strength bolt and a manufacturing method thereof, belonging to the technical field of alloy materials.

Background technique

With the continuous development of coastal areas, higher and higher requirements are put forward for the materials used in various fasteners (such as bolts, screws, nuts, etc.), such as high bolt reinforcement, resistance to marine atmospheric corrosion, etc. Compared with the general atmospheric environment, the chloride ion concentration in the marine atmospheric environment is higher, and the environment is more complex, which has caused a certain resistance to the development of my country to the marine field. The harsh environmental factors further accelerate the corrosion rate of metal materials. Every year, metal corrosion in coastal areas will directly or indirectly bring serious economic losses to the country, and traditional 42CrMo and 42CrMo4 bolt steels have poor resistance to marine atmospheric corrosion and cannot meet the requirements of long-term coastal use. Therefore, the most effective way is to improve metal materials. The corrosion resistance of marine atmosphere.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is that the present invention provides a marine atmospheric corrosion resistant high-strength bolt and a manufacturing method thereof.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

A high-strength bolt resistant to marine atmospheric corrosion, comprising the following components, in terms of mass percentage, C: 0.10-0.40; Si: 0.10-0.60; Mn: 0.30-1.20; P≤0.025; S≤0.01; Ni: 3.0- 3.5; Cu: 0.20～0.70; Mo: 0.10～0.65; V: ≤0.10; Ti: 0.02～0.10: B: 0.001～0.003; Nb: 0.04～0.10; Als≥0.015; N: 0.009～0.018; W: 0.1 ～0.8; Zr: 0.015～0.045; Re: 0.01～0.045, the gas content in the bolt: [N]≤0.008%, [H]≤0.0002%, and the balance is Fe.

Two rare earth elements, Zr and Re, are added to the bolt component of the present invention, which can further improve the tensile strength and corrosion resistance of the bolt.

A method for manufacturing high-strength bolts resistant to marine atmospheric corrosion, comprising the following steps:

S01, hot forging;

S02, precipitation adjustment treatment: the bolts formed by S01 are heated and kept at 1100 to 1250 ° C for 45 to 60 minutes, and then air-cooled quickly after the end of the heat preservation, so that the fine second phase particles are fully and uniformly dispersed and precipitation distributed on the tissue matrix of the bolt;

S03, high temperature quenching: high temperature quenching is adopted after the precipitation adjustment treatment, heating at 960 ~ 1000 ℃ to austenitize, and oil quenching after holding for 45 ~ 60min;

S04, two-stage tempering: the temperature of the first-stage tempering is 350-450 °C, and the temperature is kept for 30-50 minutes. In this stage, the copper-rich phase (ε-Cu) is mainly precipitated. After the first-stage tempering is completed, it continues without cooling After heating to 560～610℃, keep the temperature for 60～100min, that is, the second stage of tempering, at this stage, the fine second phase special carbides formed by V, Nb, Ti, W and other elements are mainly precipitated;

S05, machining, thread rolling and surface phosphating.

The hot forging can be replaced by spheroidizing annealing cold heading.

The second phase particles include Ti(C,N), V(C,N), Nb(C,N) and _W2C .

The cooling rate of the rapid air cooling is 1.5-4°C/s.

The particle size of the second phase particles ranges from 0.5 to 10 nm.

The invention provides a first-stage tempering treatment process flow of precipitation phase adjustment treatment, high temperature quenching and two-stage tempering. After the process flow, copper-rich phase (ε-Cu) and Ti can be fully dispersed and precipitated in the tempered structure. (C, N), V(C, N), Nb(C, N) and W ₂ C and other fine second phase particles are fully analyzed, so that the bolt still has high resistance to marine atmospheric corrosion when it reaches the strength level of 1040MPa performance and good plasticity.

The precipitation adjustment treatment is based on the characteristics of high dissolution temperature of carbides or carbon and nitrogen compounds of alloying elements such as V, Nb, Ti, and W in the steel. V, Nb, Ti and other alloy elements are fully dissolved in the austenite. During the process of rapid air cooling to room temperature after the heat preservation, the fine second phase particles such as Ti (C, N), V (C, N), Nb ( C, N) and so on are fully and uniformly dispersed and precipitated on the microstructure matrix, and the finely dispersed second-phase particles can play a role in pinning the grain boundaries during the reheating and high-temperature quenching and heat preservation process, and can effectively hinder the austenite grains. At the same time, it can improve the original band-like tissue and improve the uniformity of the tissue.

After the precipitation adjustment treatment is completed, it is rapidly air-cooled to room temperature and then quenched at high temperature, and heated at 960 to 1000 ° C for austenitization. The purpose is to make the alloy elements such as Ni, Mo, Cu, V, Ti, W in the steel completely or partially It is dissolved into austenite, and after quenching and cooling, martensite with a high content of the above alloy is obtained.

After quenching and cooling to room temperature, two-stage tempering is performed, and the first-stage tempering temperature is selected to be 350-450 °C, and the temperature is kept for 30-50 min. The purpose is to precipitate a copper-rich phase ( ε-Cu), while the precipitation of Cu element and the segregation of Cu element can induce the precipitation of W, V, Nb, Ti and other element carbides, after the first stage of tempering, continue to heat to 560 ~ 610 without cooling ℃ for high temperature tempering, and heat preservation for 60 to 100 minutes (second stage tempering). Tempering at a high temperature of 560-610 °C is to make V, Nb, Ti, W and other elements form fine second-phase special carbides to play a role in precipitation strengthening (secondary hardening) and improve the strength of the steel.

The _second phase special carbides include TiC, VC, NbC and W2C.

As a strong carbide forming element, W element has stronger bonding force with carbon than Mo element. The tungsten element dissolved into the matrix during high temperature quenching mainly precipitates W ₂ C when tempering at 560-610 ℃, and makes Mo element more Most of them are retained in the matrix structure, so that the matrix structure maintains high corrosion resistance. At the same time, the carbides of tungsten formed by tempering are not easy to aggregate and grow during high temperature tempering. They are dispersed on the martensite matrix and can be combined with Carbides of other elements together improve the mechanical properties of the bolt, causing a secondary hardening effect.

The addition of high Ni element, appropriate amount of Mo and Cu elements to the bolt can form a passive film on the surface of the bolt steel, reduce electrochemical corrosion, and improve the marine atmospheric corrosion resistance of the bolt steel. In view of the adopted processes such as precipitation adjustment treatment, high temperature quenching, and two-stage tempering, the corresponding alloy elements have fully exerted their synergistic effects to achieve the effects of grain refinement strengthening, precipitation strengthening, and promoting the formation of passivation films. After the fire, a tempered martensite structure is finally formed, which improves the strength, toughness and plasticity of the bolt, and the corrosion resistance of the marine atmosphere.

The addition of Cu element to steel can form secondary precipitation products on its surface. As a cathode, the surface of steel can be purified by anode. Cu is enriched in the inner rust layer in the form of CuO in weathering steel, which can well isolate corrosive media and reduce energy consumption. Cl ions promote corrosion and increase the polarization resistance of the steel, resulting in enhanced protection of the rust layer, thereby improving the marine atmospheric corrosion performance of the steel. At the same time, the addition of Cu and Ni alloying elements can accelerate the cathodic reduction of the rust layer and inhibit the The anode dissolves and improves the corrosion resistance of steel. The addition of rare earth element Re can purify molten steel, deoxidize and desulfurize, and gradually transform the banded manganese sulfide inclusions in the steel into spherical and dispersed rare earth inclusions, refine the structure, and improve mechanical properties. Enhance the adhesion between the rust layer and the steel substrate to improve the atmospheric corrosion resistance of the steel. The role of Mo element: improve the compactness and adhesion of the rust layer, promote the formation of an amorphous oxide film to improve the properties of the rust layer, effectively inhibit the intrusion of Cl ions, and improve the corrosion resistance of the test steel. The presence of Ni in the steel can positively shift its self-corrosion potential, thereby increasing its stability and promoting the formation of superparamagnetic α-FeOOH phase with a particle size of less than 15 nm in the inner rust layer, thus increasing the corrosion resistance of the inner rust layer. Density, thereby improving resistance to marine atmospheric corrosion.

The tensile strength of the 1040MPa grade high-strength bolts manufactured by the invention is between 1075MPa and 1200MPa, the elongation after fracture is ≥12.5%, the section shrinkage rate is 50% to 60%, and the impact energy at -20°C is greater than 41KV ₂ /J, And has excellent resistance to marine atmospheric corrosion.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. The specific embodiments described herein are only used to explain the present invention, and are not intended to limit the present invention.

Example 1

A high-strength bolt resistant to marine atmospheric corrosion, comprising the following components, in terms of mass percentage, C: 0.10; Si: 0.10; Mn: 0.30; P: 0.025; S: 0.01; Ni: 3.0; Cu: 0.20; Mo: 0.10; V: 0.10; Ti: 0.02: B: 0.001; Nb: 0.04; Als: 0.015; N: 0.009; W: 0.1; Zr: 0.015; Re: 0.01, gas content in the bolt: [N]≤0.008%, [H]≤0.0002%, and the balance is Fe.

A method for manufacturing high-strength bolts resistant to marine atmospheric corrosion, comprising the following steps:

S01, hot forging;

S02, precipitation adjustment treatment: The bolts formed by S01 are heated and kept at 1100°C for 45 minutes, and then quickly air-cooled after the end of the heat preservation, so that the fine second phase particles are fully and uniformly dispersed and distributed on the tissue matrix of the bolts;

S03, high temperature quenching: high temperature quenching is adopted after the precipitation adjustment treatment, heating at 960 ° C to austenitize, and oil quenching after holding for 45 minutes;

S04, two-stage tempering: the temperature of the first-stage tempering is 350-450 °C, and the temperature is kept for 30-50 minutes. In this stage, the copper-rich phase (ε-Cu) is mainly precipitated; after the first-stage tempering is completed, it is continued without cooling. After heating to 570°C, hold the temperature for 100min, that is, the second stage of tempering, at this stage, the fine second-phase special carbides formed by V, Nb, Ti, W and other elements are mainly precipitated;

S05, machining, thread rolling and surface phosphating.

The second phase particles include Ti(C,N), V(C,N), Nb(C,N) and _W2C .

The cooling rate of the rapid air cooling is 2°C/s.

The particle size of the second phase particles ranges from 0.5 to 10 nm.

The _second phase special carbides include TiC, VC, NbC and W2C.

After the above process, the tensile strength of the bolt is 1089MPa, the area shrinkage rate is 56.2%, and the impact energy at -20°C is greater than 77.8KV ₂ /J.

In this example, adding Cu element to the steel can form secondary precipitation products on its surface, which acts as a cathode to produce anode ^purification on the surface of the steel. Acceleration, lower concentration of Ni can improve the corrosion resistance of HSO ₃ ^-1 , while adding Cu and Ni alloying elements can accelerate the cathodic reduction of the rust layer, inhibit the anodic dissolution, and improve the corrosion resistance of the steel. The addition of rare earth element Re can purify molten steel, deoxidize and desulfurize, and gradually transform the banded manganese sulfide inclusions in the steel into spherical and dispersed rare earth inclusions, refine the structure and improve mechanical properties. The adhesion between the rust layer and the steel substrate can improve the atmospheric corrosion resistance of the steel.

The marine atmospheric corrosion resistance test is carried out in accordance with the "Salt Spray Test of Artificial Atmosphere Corrosion Test" (GB/T 10125-2012/ISO9227:2006). The main test conditions include: uniform spray concentration of 50g·L ^-1 ±5g·L ^{- 1} sodium chloride solution, the pH value is 6.5~7.2, the temperature in the test chamber is kept at 35℃±2℃, and the average sedimentation rate of the salt spray on the horizontal area of 80cm ² is 1.5mL·h ^-1 ±0.5mL· h ^-1 , and the test period is set to 2, 4, 8, 12, 18, and 25 days. When the test period was set to 18 and 25 days, the thickness loss was controlled to be 60-90 μm.

The open circuit potential (self-corrosion potential) was measured by the electrochemical test method: the electrochemical test device adopts a three-electrode system, the working electrode (ie the research electrode) is the sample to be tested, and the working area is 1 cm ² ; the reference electrode is saturated calomel Electrode; the auxiliary electrode is platinum sheet or platinum wire mesh. The test solution was a NaCl solution with a concentration of (3.50±0.05)%. The test temperature is room temperature. The self-corrosion potential is controlled to be -0.605V to -0.630V.

Example 2

A marine atmospheric corrosion resistant high-strength bolt, comprising the following components, in terms of mass percentage, C: 0.40; Si: 0.60; Mn: 1.20; P: 0.020; S: 0.005; Ni: 3.5; Cu: 0.70; Mo: 0.65; V: 0.05; Ti: 0.10: B: 0.003; Nb: 0.10; Als: 0.02; N: 0.018; W: 0.8; Zr: 0.045; [H]≤0.0002%, and the balance is Fe.

A method for manufacturing high-strength bolts resistant to marine atmospheric corrosion, comprising the following steps:

S01, spheroidizing annealing cold heading forming;

S02, precipitation adjustment treatment: The bolts formed by S01 are heated and kept at 1100°C for 45 minutes, and then quickly air-cooled after the end of the heat preservation, so that the fine second phase particles are fully and uniformly dispersed and distributed on the tissue matrix of the bolts;

S03, high temperature quenching: high temperature quenching is adopted after the precipitation adjustment treatment, heating at 960 ° C to austenitize, and oil quenching after holding for 45 minutes;

S04, two-stage tempering: the temperature of the first-stage tempering is 350-450 °C, and the temperature is kept for 30-50 minutes. In this stage, the copper-rich phase (ε-Cu) is mainly precipitated; after the first-stage tempering is completed, it is continued without cooling. After heating to 580°C, hold for 100min, that is, the second stage of tempering, in this stage, the fine second-phase special carbides formed by elements such as V, Nb, Ti, and W are mainly precipitated;

S05, machining, thread rolling and surface phosphating.

The second phase particles include Ti(C,N), V(C,N), Nb(C,N) and _W2C .

The cooling rate of the rapid air cooling is 4°C/s.

The particle size of the second phase particles ranges from 0.5 to 10 nm.

The _second phase special carbides include TiC, VC, NbC and W2C.

After the above process, the tensile strength of the bolt is 1045MPa, the area shrinkage rate is 58.3%, and the impact energy at -20°C is greater than 82.1KV ₂ /J.

Example 3

A high-strength bolt resistant to marine atmospheric corrosion, comprising the following components, in terms of mass percentage, C: 0.20; Si: 0.30; Mn: 0.80; P: 0.01; S: 0.001; Ni: 3.3; Cu: 0.50; Mo: 0.35; V: 0.010; Ti: 0.09: B: 0.002; Nb: 0.08; Als: 0.03; N: 0.015; W: 0.5; Zr: 0.03; [H]≤0.0002%, and the balance is Fe.

A method for manufacturing high-strength bolts resistant to marine atmospheric corrosion, comprising the following steps:

S01, hot forging;

S02, precipitation adjustment treatment: the bolts formed by S01 are heated and kept at 1150°C for 45 minutes, and then quickly air-cooled after the end of the heat preservation, so that the fine second-phase particles are fully and uniformly dispersed and distributed on the tissue matrix of the bolts;

S03, high temperature quenching: high temperature quenching is adopted after the precipitation adjustment treatment, heating at 980 ° C to austenitize, and oil quenching after holding for 45 minutes;

S04, two-stage tempering: the temperature of the first-stage tempering is 350-450 °C, and the temperature is kept for 30-50 minutes. In this stage, the copper-rich phase (ε-Cu) is mainly precipitated; after the first-stage tempering is completed, it is continued without cooling. After heating to 570°C, hold the temperature for 100min, that is, the second stage of tempering, at this stage, the fine second-phase special carbides formed by V, Nb, Ti, W and other elements are mainly precipitated;

S05, machining, thread rolling and surface phosphating.

The second phase particles include Ti(C,N), V(C,N), Nb(C,N) and _W2C .

The cooling rate of the rapid air cooling is 3°C/s.

The particle size of the second phase particles ranges from 0.5 to 10 nm.

The _second phase special carbides include TiC, VC, NbC and W2C.

After the above process, the tensile strength of the bolt is 1070MPa, the area shrinkage rate is 58.3%, and the impact energy at -20°C is greater than 46.7KV ₂ /J.

Example 4

A high-strength bolt resistant to marine atmospheric corrosion, comprising the following components, in terms of mass percentage, C: 0.10-0.40; Si: 0.10-0.60; Mn: 0.30-1.20; P≤0.025; S≤0.01; Ni: 3.0- 3.5; Cu: 0.20～0.70; Mo: 0.10～0.65; V: ≤0.10; Ti: 0.02～0.10: B: 0.001～0.003; Nb: 0.04～0.10; Als≥0.015; N: 0.009～0.018; W: 0.1 ～0.8; Zr: 0.015～0.045; Re: 0.01～0.045, the gas content in the bolt: [N]≤0.008%, [H]≤0.0002%, and the balance is Fe.

A method for manufacturing high-strength bolts resistant to marine atmospheric corrosion, comprising the following steps:

S01, hot forging;

S02, precipitation adjustment treatment: the bolts formed by S01 are heated and kept at 1150°C for 45 minutes, and then quickly air-cooled after the end of the heat preservation, so that the fine second-phase particles are fully and uniformly dispersed and distributed on the tissue matrix of the bolts;

S03, high temperature quenching: high temperature quenching is adopted after the precipitation adjustment treatment, heating at 960 ° C to austenitize, and oil quenching after holding for 45 minutes;

S04, two-stage tempering: the temperature of the first-stage tempering is 350-450 °C, and the temperature is kept for 30-50 minutes. In this stage, the copper-rich phase (ε-Cu) is mainly precipitated; after the first-stage tempering is completed, it is continued without cooling. After heating to 570°C, hold the temperature for 100min, that is, the second stage of tempering, at this stage, the fine second-phase special carbides formed by V, Nb, Ti, W and other elements are mainly precipitated;

S05, machining, thread rolling and surface phosphating.

The second phase particles include Ti(C,N), V(C,N), Nb(C,N) and _W2C .

The cooling rate of the rapid air cooling is 1.5-4°C/s.

The particle size of the second phase particles ranges from 0.5 to 10 nm.

The _second phase special carbides include TiC, VC, NbC and W2C.

After the above process, the tensile strength of the bolt is 1082MPa, the area shrinkage rate is 57.5%, and the impact energy at -20°C is greater than 54.6KV ₂ /J.

Example 5

A high-strength bolt resistant to marine atmospheric corrosion, comprising the following components, in terms of mass percentage, C: 0.10-0.40; Si: 0.10-0.60; Mn: 0.30-1.20; P≤0.025; S≤0.01; Ni: 3.0- 3.5; Cu: 0.20～0.70; Mo: 0.10～0.65; V: ≤0.10; Ti: 0.02～0.10: B: 0.001～0.003; Nb: 0.04～0.10; Als≥0.015; N: 0.009～0.018; W: 0.1 ～0.8; Zr: 0.015～0.045; Re: 0.01～0.045, the gas content in the bolt: [N]≤0.008%, [H]≤0.0002%, and the balance is Fe.

A method for manufacturing high-strength bolts resistant to marine atmospheric corrosion, characterized by comprising the following steps:

S01, hot forging;

S02, precipitation adjustment treatment: the bolts formed by S01 are heated and kept at 1150°C for 45 minutes, and then quickly air-cooled after the end of the heat preservation, so that the fine second-phase particles are fully and uniformly dispersed and distributed on the tissue matrix of the bolts;

S03, high temperature quenching: high temperature quenching is adopted after the precipitation adjustment treatment, heating at 970 ° C to austenitize, and oil quenching after holding for 45 minutes;

S04, two-stage tempering: the temperature of the first-stage tempering is 350-450 °C, and the temperature is kept for 30-50 minutes. In this stage, the copper-rich phase (ε-Cu) is mainly precipitated; after the first-stage tempering is completed, it is continued without cooling. After heating to 580°C, hold for 100min, that is, the second stage of tempering, in this stage, the fine second-phase special carbides formed by elements such as V, Nb, Ti, and W are mainly precipitated;

S05, machining, thread rolling and surface phosphating.

The second phase particles include Ti(C,N), V(C,N), Nb(C,N) and _W2C .

The cooling rate of the rapid air cooling is 1.5-4°C/s.

The particle size of the second phase particles ranges from 0.5 to 10 nm.

The _second phase special carbides include TiC, VC, NbC and W2C.

After the above process, the tensile strength of the bolt is 1072MPa, the section shrinkage rate is 57.7%, and the impact energy at -20°C is greater than 55KV ₂ /J.

Example 6

A high-strength bolt resistant to marine atmospheric corrosion, comprising the following components, in terms of mass percentage, C: 0.10-0.40; Si: 0.10-0.60; Mn: 0.30-1.20; P≤0.025; S≤0.01; Ni: 3.0- 3.5; Cu: 0.20～0.70; Mo: 0.10～0.65; V: ≤0.10; Ti: 0.02～0.10: B: 0.001～0.003; Nb: 0.04～0.10; Als≥0.015; N: 0.009～0.018; W: 0.1 ～0.8; Zr: 0.015～0.045; Re: 0.01～0.045, the gas content in the bolt: [N]≤0.008%, [H]≤0.0002%, and the balance is Fe.

A method for manufacturing high-strength bolts resistant to marine atmospheric corrosion, comprising the following steps:

S01, hot forging;

S02, precipitation adjustment treatment: The bolts formed by S01 are heated and kept at 1200°C for 45 minutes, and then quickly air-cooled after the end of the heat preservation, so that the fine second phase particles are fully and uniformly dispersed and distributed on the tissue matrix of the bolts;

S03, high temperature quenching: high temperature quenching is adopted after the precipitation adjustment treatment, heating at 960 ° C to austenitize, and oil quenching after holding for 45 minutes;

S04, two-stage tempering: the temperature of the first-stage tempering is 350-450 °C, and the temperature is kept for 30-50 minutes. In this stage, the copper-rich phase (ε-Cu) is mainly precipitated; after the first-stage tempering is completed, it is continued without cooling. After heating to 570°C, hold the temperature for 100min, that is, the second stage of tempering, at this stage, the fine second-phase special carbides formed by V, Nb, Ti, W and other elements are mainly precipitated;

S05, machining, thread rolling and surface phosphating.

The second phase particles include Ti(C,N), V(C,N), Nb(C,N) and _W2C .

The cooling rate of the rapid air cooling is 1.5-4°C/s.

The particle size of the second phase particles ranges from 0.5 to 10 nm.

The _second phase special carbides include TiC, VC, NbC and W2C.

After the above process, the tensile strength of the bolt is 1093MPa, the area shrinkage rate is 56.8%, and the impact energy at -20°C is greater than 71.3KV ₂ /J.

Example 7

A high-strength bolt resistant to marine atmospheric corrosion, comprising the following components, in terms of mass percentage, C: 0.10-0.40; Si: 0.10-0.60; Mn: 0.30-1.20; P≤0.025; S≤0.01; Ni: 3.0- 3.5; Cu: 0.20～0.70; Mo: 0.10～0.65; V: ≤0.10; Ti: 0.02～0.10: B: 0.001～0.003; Nb: 0.04～0.10; Als≥0.015; N: 0.009～0.018; W: 0.1 ～0.8; Zr: 0.015～0.045; Re: 0.01～0.045, the gas content in the bolt: [N]≤0.008%, [H]≤0.0002%, and the balance is Fe.

A method for manufacturing high-strength bolts resistant to marine atmospheric corrosion, comprising the following steps:

S01, hot forging;

S02, precipitation adjustment treatment: the bolts formed by S01 are heated and kept at 1250°C for 60 minutes, and then quickly air-cooled after the end of the heat preservation, so that the fine second-phase particles are fully and uniformly dispersed and distributed on the tissue matrix of the bolt;

S03, high temperature quenching: high temperature quenching is adopted after the precipitation adjustment treatment, heating at 1000 ℃ to austenitize, and oil quenching after holding for 60 minutes;

S04, two-stage tempering: the temperature of the first-stage tempering is 350 °C, and the temperature is kept for 30 minutes. In this stage, the copper-rich phase (ε-Cu) is mainly precipitated; after the first-stage tempering is completed, the temperature is continued to rise to 610 °C without cooling. After 60min of heat preservation, that is, the second stage of tempering, this stage mainly precipitates the fine second-phase special carbides formed by elements such as V, Nb, Ti, W;

S05, machining, thread rolling and surface phosphating.

The second phase particles include Ti(C,N), V(C,N), Nb(C,N) and _W2C .

The cooling rate of the rapid air cooling is 1.5°C/s.

The particle size of the second phase particles ranges from 0.5 to 10 nm.

The _second phase special carbides include TiC, VC, NbC and W2C.

Example 8

The difference between this embodiment and Embodiment 7 is only:

S04, two-stage tempering: the temperature of the first-stage tempering is 450 °C, and the temperature is kept for 50 minutes. After the first-stage tempering is completed, the temperature is continued to rise to 560 °C without cooling, and the temperature is kept for 100 minutes, that is, the second-stage tempering.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (6)

1. A method for manufacturing high-strength bolts resistant to marine atmospheric corrosion, the bolts include the following components, in terms of mass percentage, C: 0.10~0.40; Si: 0.10~0.60; Mn: 0.30~1.20; P≤0.025; S≤ 0.01; Ni: 3.0~3.5; Cu: 0.20~0.70; Mo: 0.10~0.65; V: ≤0.10; Ti: 0.02~0.10: B: 0.001~0.003; Nb: 0.04~0.10; Als≥0.015; N: 0.009 ~0.018; W: 0.1~0.8; Zr: 0.015~0.045; Re: 0.01~0.045, the gas content in the bolt: [N]≤0.008%, [H]≤0.0002%, the balance is Fe; It is characterized in that: the manufacturing method comprises the following steps: S01, hot forging; S02, precipitation adjustment treatment: The bolts formed by S01 are heated and kept at 1100-1250°C for 45-60 minutes, and then air-cooled quickly after the end of the heat preservation, so that the fine second-phase particles are fully and uniformly dispersed and precipitation distributed on the tissue matrix of the bolt; S03, high temperature quenching: high temperature quenching is adopted after the precipitation adjustment treatment, heating at 960~1000℃ to austenitize, and oil quenching after holding for 45~60min; S04, two-stage tempering: the temperature of the first stage tempering is 350~450℃, and the temperature is kept for 30~50min, and the copper-rich phase ε-Cu is precipitated at this stage; After ~610°C, keep the temperature for 60~100min, that is, the second stage of tempering, at this stage, the fine second-phase special carbides formed by V, Nb, Ti, and W elements are precipitated; S05, machining, thread rolling and surface phosphating. 2 . The method for manufacturing a high-strength bolt resistant to marine atmospheric corrosion according to claim 1 , wherein the hot forging can be replaced by spheroidizing annealing and cold heading. 3 . 3 . The method for manufacturing high-strength bolts resistant to marine atmospheric corrosion according to claim 1 , wherein the second phase particles comprise Ti (C, N), V (C, N), Nb (C , N) and W ₂ C. 4 . The method for manufacturing a high-strength bolt resistant to marine atmospheric corrosion according to claim 1 , wherein the cooling rate of the rapid air cooling is 1.5 to 4° C./s. 5 . 5 . The method for manufacturing a high-strength bolt resistant to marine atmospheric corrosion according to claim 1 , wherein the particle size of the second phase particles ranges from 0.5 to 10 nm. 6 . 6 . The method for manufacturing a high-strength bolt resistant to marine atmospheric corrosion according to claim 1 , wherein the second-phase special carbides include TiC, VC, NbC and W ₂ C. 7 .