Corrosion-resistant bolt and preparation method thereof

Abstract

The invention relates to the technical field of fasteners, and provides a corrosion-resistant bolt and a preparation method thereof. The preparation method of the corrosion-resistant bolt comprises the following steps that S1, all the component raw materials are subjected to smelting and casting forming after being prepared, and an as-cast blank is obtained; s2, after the as-cast blank is subjected to heat treatment, cold heading forming and thread rolling treatment are sequentially conducted, and a bolt body is obtained; and S3, after the bolt body is subjected to a hot galvanizing process, passivating treatment is conducted through a passivating solution, drying and cooling are conducted, and the corrosion-resistant bolt is obtained. The passivation solution is prepared from the following components in parts by weight: 120 to 150 parts of ammonium molybdate, 40 to 60 parts of nickel sulfate, 30 to 90 parts of ethanol, 15 to 21 parts of an organic passivator, 60 to 70 parts of propyltrimethylsilane, 3 to 5 parts of ZrB2-ZrC nano composite powder, 30 to 80 parts of a surfactant and 500 to 1000 parts of water. By means of the technical scheme, the problem that in the prior art, the corrosion resistance of the bolt is insufficient is solved.

Description

Technical Field

[0001] This invention relates to the field of fastener technology, specifically to a corrosion-resistant bolt and its preparation method. Background Technology

[0002] Bolts are one of the most widely used basic fasteners in the field of mechanical manufacturing, and their performance directly affects the stability and service life of various equipment and structures. In many fields such as industrial production, construction engineering, transportation, and marine engineering, bolts are often exposed to complex and harsh service environments for extended periods. Corrosion easily occurs on the bolt surface, leading to a decrease in mechanical strength and dimensional inaccuracies. For example, high salt spray concentrations in marine environments accelerate oxidation reactions on the bolt surface, causing traditional bolts to rust quickly in such conditions. In industrial settings, acidic and alkaline waste liquids and corrosive gases can damage the protective layer on the bolt surface, triggering deep corrosion.

[0003] To improve the corrosion resistance of bolts, various protective measures have been developed, among which hot-dip galvanizing has become one of the most widely used surface protection technologies. However, traditional hot-dip galvanized bolts still have significant defects. The zinc coating itself contains microscopic defects such as pores and microcracks, allowing corrosive ions to easily penetrate into the bolt substrate, leading to zinc layer detachment and substrate corrosion. Furthermore, some technologies attempt to seal these defects by passivating after galvanizing. Commonly used passivation solutions primarily consist of chromates and molybdates, but the passivation film formed by traditional passivation solutions lacks sufficient density and has limited ability to block corrosive ions. Therefore, a corrosion-resistant bolt is urgently needed. Summary of the Invention

[0004] This invention proposes a corrosion-resistant bolt and its preparation method, which solves the problem of insufficient corrosion resistance of bolts in related technologies.

[0005] The technical solution of the present invention is as follows: This invention proposes a method for preparing corrosion-resistant bolts, comprising the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is subjected to cold heading and thread rolling to obtain the bolt body. S3. After the bolt body is hot-dip galvanized, it is passivated with passivating liquid, dried and cooled to obtain a corrosion-resistant bolt. The passivation solution comprises the following components in parts by weight: 120-150 parts ammonium molybdate, 40-60 parts nickel sulfate, 30-90 parts ethanol, 15-21 parts organic passivating agent, 60-70 parts propyltrimethylsilane, 3-5 parts ZrB2-ZrC nanocomposite powder, 30-80 parts surfactant, and 500-1000 parts water.

[0006] As a further technical solution, the preparation method of the ZrB2-ZrC nanocomposite powder includes the following steps: mixing zirconium powder and boron carbide, and then ball milling to obtain the ZrB2-ZrC nanocomposite powder.

[0007] In this invention, the ZrB2-ZrC nanocomposite powder is prepared by in-situ ball milling reaction of zirconium powder and boron carbide to form submicron powder with embedded nanoparticles. There are no obvious interfacial gaps, and separation or stratification will not occur. This ensures that after it is dispersed in the passivation solution, it can still maintain a uniform distribution of the two phases, so that the performance of each region of the passivation film is consistent and there are no local defects.

[0008] As a further technical solution, the molar ratio of zirconium powder to boron carbide is 3:1 to 1.2.

[0009] As a further technical solution, the ball mill rotation speed is 500~600 r / min, and the ball milling time is 32~35 h.

[0010] As a further technical solution, the median particle size of the ZrB2-ZrC nanocomposite powder is 100~150nm.

[0011] As a further technical solution, the organic passivating agent includes 1-phenyl-5-mercaptotetrazole and / or hexamethylenediaminetetramethylenephosphonic acid.

[0012] Preferably, the organic passivating agent comprises 1-phenyl-5-mercaptotetrazole and hexamethylenediaminetetramethylenephosphonic acid.

[0013] In this invention, 1-phenyl-5-mercaptotetrazole and hexamethylenediaminetetramethylenephosphonic acid are used in combination as organic passivating agents to improve the corrosion resistance of bolts. Specifically, the thiol group and nitrogen heterocycle in the 1-phenyl-5-mercaptotetrazole molecule can adsorb onto the Zn on the zinc plating surface. 2+ It forms a stable chelating film, filling the micropore defects of the passivation film, while inhibiting the excessive dissolution of the zinc plating layer in the acidic passivation solution, thus improving the density of the passivation film; hexamethylenediaminetetramethylenephosphonic acid can react with Ni in the passivation solution. 2+ Zn 2 + Complexation is used to regulate the passivation reaction rate and avoid the formation of a loose and porous passivation film due to excessively rapid reaction.

[0014] As a further technical solution, when the organic passivating agent is 1-phenyl-5-mercaptotetrazole and hexamethylenediaminetetramethylenephosphonic acid, the mass ratio of 1-phenyl-5-mercaptotetrazole and hexamethylenediaminetetramethylenephosphonic acid is 1:5~6.

[0015] In this invention, the corrosion resistance of the bolts is further improved by further adjusting the mass ratio of 1-phenyl-5-mercaptotetrazole and hexamethylenediaminetetramethylenephosphonic acid to 1:5~6.

[0016] As a further technical solution, the pH of the passivation solution is 4-5.

[0017] As a further technical solution, the passivation temperature is 50~60℃; the passivation time is 60~90s.

[0018] As a further technical solution, the bolt body is composed of the following components by weight percentage: C 0.35%~0.45%, Mn 0.3%~0.65%, Cr 2.8%~3.5%, Ni 0.5%~1%, Al 0.5%~1.8%, Cu 0.3%~0.4%, Mo 0.15%~0.3%, Sb 0.02%~0.04%, P≤0.015%, S≤0.02%, with the remainder being Fe and other unavoidable impurities.

[0019] The present invention also proposes a corrosion-resistant bolt, which is prepared by any of the preparation methods described herein.

[0020] The working principle and beneficial effects of this invention are as follows: In this invention, the corrosion resistance of bolts is improved by adding ZrB2-ZrC nanocomposite powder to the passivation solution. ZrB2-ZrC nanocomposite powder itself exhibits excellent corrosion resistance, and it can also fill the pores and microcracks in the passivation film, constructing a nanoscale sealing barrier within the film layer. This significantly reduces the number of permeation channels for corrosive ions and delays the occurrence of corrosion reactions. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] In the following comparative examples, the median particle size of nano ZrC is 150 nm; the median particle size of nano ZrB2 is 150 nm.

[0023] Example 1 The bolt body is composed of the following components by weight percentage: C 0.35%, Mn 0.3%, Cr 2.8%, Ni 0.5%, Al 0.5%, Cu 0.3%, Mo 0.15%, Sb 0.02%, P 0.015%, S 0.02%, with the remainder being Fe and other unavoidable impurities; The preparation method of ZrB2-ZrC nanocomposite powder includes the following steps: zirconium powder and boron carbide are mixed in a molar ratio of 3:1 and then ball-milled at a speed of 500 r / min for 35 h to obtain ZrB2-ZrC nanocomposite powder with a median particle size of 150 nm. The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 60 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 4 and a temperature of 50℃. The passivation solution comprises the following components in parts by weight: 120 parts ammonium molybdate, 40 parts nickel sulfate, 30 parts ethanol, 15 parts benzotriazole, 60 parts propyltrimethylsilane, 3 parts ZrB2-ZrC nanocomposite powder, 30 parts sodium tetradecyl sulfonate, and 500 parts water.

[0024] Example 2 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The preparation method of ZrB2-ZrC nanocomposite powder includes the following steps: zirconium powder and boron carbide are mixed in a molar ratio of 3:1 and then ball-milled at a speed of 600 r / min for 32 h to obtain ZrB2-ZrC nanocomposite powder with a median particle size of 100 nm. The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 21 parts benzotriazole, 70 parts propyltrimethylsilane, 5 parts ZrB2-ZrC nanocomposite powder, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0025] Example 3 The bolt body is composed of the following components by weight percentage: C 0.40%, Mn 0.45%, Cr 3.1%, Ni 0.8%, Al 1.5%, Cu 0.35%, Mo 0.23%, Sb 0.03%, P 0.012%, S 0.02%, with the remainder being Fe and other unavoidable impurities; The preparation method of ZrB2-ZrC nanocomposite powder includes the following steps: zirconium powder and boron carbide are mixed in a molar ratio of 3:1.2 and then ball-milled at a speed of 550 r / min for 34 h to obtain ZrB2-ZrC nanocomposite powder with a median particle size of 150 nm. The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 80 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 4.5 and a temperature of 55℃. The passivation solution comprises the following components in parts by weight: 140 parts ammonium molybdate, 50 parts nickel sulfate, 60 parts ethanol, 16 parts benzotriazole, 65 parts propyltrimethylsilane, 4 parts ZrB2-ZrC nanocomposite powder, 50 parts sodium tetradecyl sulfonate, and 800 parts water.

[0026] Example 4 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The preparation method of ZrB2-ZrC nanocomposite powder includes the following steps: zirconium powder and boron carbide are mixed in a molar ratio of 3:1 and then ball-milled at a speed of 600 r / min for 32 h to obtain ZrB2-ZrC nanocomposite powder with a median particle size of 100 nm. The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 21 parts 1-phenyl-5-mercaptotetrazole, 70 parts propyltrimethylsilane, 5 parts ZrB2-ZrC nanocomposite powder, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0027] Example 5 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The preparation method of ZrB2-ZrC nanocomposite powder includes the following steps: zirconium powder and boron carbide are mixed in a molar ratio of 3:1 and then ball-milled at a speed of 600 r / min for 32 h to obtain ZrB2-ZrC nanocomposite powder with a median particle size of 100 nm. The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 21 parts hexamethylenediaminetetramethylenephosphonic acid, 70 parts propyltrimethylsilane, 5 parts ZrB2-ZrC nanocomposite powder, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0028] Example 6 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The preparation method of ZrB2-ZrC nanocomposite powder includes the following steps: zirconium powder and boron carbide are mixed in a molar ratio of 3:1 and then ball-milled at a speed of 600 r / min for 32 h to obtain ZrB2-ZrC nanocomposite powder with a median particle size of 100 nm. The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 3.5 parts 1-phenyl-5-mercaptotetrazole, 17.5 parts hexamethylenediaminetetramethylenephosphonic acid, 70 parts propyltrimethylsilane, 5 parts ZrB2-ZrC nanocomposite powder, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0029] Example 7 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The preparation method of ZrB2-ZrC nanocomposite powder includes the following steps: zirconium powder and boron carbide are mixed in a molar ratio of 3:1 and then ball-milled at a speed of 600 r / min for 32 h to obtain ZrB2-ZrC nanocomposite powder with a median particle size of 100 nm. The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 3 parts 1-phenyl-5-mercaptotetrazole, 18 parts hexamethylenediaminetetramethylenephosphonic acid, 70 parts propyltrimethylsilane, 5 parts ZrB2-ZrC nanocomposite powder, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0030] Example 8 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The preparation method of ZrB2-ZrC nanocomposite powder includes the following steps: zirconium powder and boron carbide are mixed in a molar ratio of 3:1 and then ball-milled at a speed of 600 r / min for 32 h to obtain ZrB2-ZrC nanocomposite powder with a median particle size of 100 nm. The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 4.2 parts 1-phenyl-5-mercaptotetrazole, 16.8 parts hexamethylenediaminetetramethylenephosphonic acid, 70 parts propyltrimethylsilane, 5 parts ZrB2-ZrC nanocomposite powder, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0031] Example 9 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The preparation method of ZrB2-ZrC nanocomposite powder includes the following steps: zirconium powder and boron carbide are mixed in a molar ratio of 3:1 and then ball-milled at a speed of 600 r / min for 32 h to obtain ZrB2-ZrC nanocomposite powder with a median particle size of 100 nm. The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 2.5 parts 1-phenyl-5-mercaptotetrazole, 18.5 parts hexamethylenediaminetetramethylenephosphonic acid, 70 parts propyltrimethylsilane, 5 parts ZrB2-ZrC nanocomposite powder, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0032] Comparative Example 1 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 21 parts benzotriazole, 70 parts propyltrimethylsilane, 2.5 parts nano ZrB, 2.5 parts nano ZrC, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0033] Comparative Example 2 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 21 parts benzotriazole, 70 parts propyltrimethylsilane, 25 parts nano ZrB, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0034] Comparative Example 3 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 21 parts benzotriazole, 70 parts propyltrimethylsilane, 5 parts nano ZrC, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0035] Comparative Example 4 The bolt body is composed of the following components by weight percentage: C 0.45%, Mn 0.65%, Cr 3.5%, Ni 1%, Al 1.8%, Cu 0.4%, Mo 0.3%, Sb 0.04%, P 0.01%, S 0.015%, with the remainder being Fe and other unavoidable impurities; The method for preparing corrosion-resistant bolts includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is cold-forged and thread-rolled in sequence to obtain the bolt body; S3. After the bolt body is hot-dip galvanized, a galvanized bolt is obtained. The galvanized bolt is then passivated with a passivation solution for 90 seconds, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution has a pH of 5 and a temperature of 60℃. The passivation solution comprises the following components in parts by weight: 150 parts ammonium molybdate, 60 parts nickel sulfate, 90 parts ethanol, 21 parts benzotriazole, 70 parts propyltrimethylsilane, 80 parts sodium tetradecyl sulfonate, and 1000 parts water.

[0036] The corrosion resistance of the corrosion-resistant bolts prepared in Examples 1-9 and Comparative Examples 1-4 were tested respectively: Corrosion resistance: The corrosion resistance performance was tested according to the neutral salt spray test method in GB / T 10125-2021 "Civilization test in artificial atmosphere - Salt spray test". The time when corrosion began to appear was recorded. The test temperature was 35℃, the concentration of sodium chloride solution was 50g / L, and the pH value was 7. The results are shown in Table 1 below.

[0037] Table 1 Corrosion Resistance Test Results

[0038] By comparing the data of Examples 1-3 and Comparative Examples 1-4, it was found that the bolts prepared by adding ZrB2-ZrC nanocomposite powder to the passivation solution in Examples 1-3 took longer to begin to corrode than those in Comparative Examples 1-4. This indicates that adding ZrB2-ZrC nanocomposite powder to the passivation solution can improve the corrosion resistance of the bolts.

[0039] Comparing the data from Examples 2 and 4-9, the bolts prepared in Examples 6-9, using a combination of 1-phenyl-5-mercaptotetrazole and hexamethylenediaminetetramethylenephosphonic acid as organic passivating agents, showed a longer time before corrosion began compared to Examples 2 and 4-5. This indicates that using a combination of 1-phenyl-5-mercaptotetrazole and hexamethylenediaminetetramethylenephosphonic acid as organic passivating agents can improve the corrosion resistance of bolts. Comparing the data from Examples 6-9, it was found that in Examples 6-7, by further adjusting the mass ratio of 1-phenyl-5-mercaptotetrazole to hexamethylenediaminetetramethylenephosphonic acid to 1:5-6, the corrosion resistance of bolts could be further improved.

[0040] The above are merely 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 within the protection scope of the present invention.

Claims

1. A method for preparing a corrosion-resistant bolt, characterized in that, Includes the following steps: S1. After the raw materials of each component are mixed, they are melted and cast to obtain a cast blank. S2. After heat treatment, the cast blank is subjected to cold heading and thread rolling to obtain the bolt body. S3. After the bolt body is hot-dip galvanized, it is passivated in a passivation solution, dried, and cooled to obtain a corrosion-resistant bolt. The passivation solution comprises the following components in parts by weight: 120-150 parts ammonium molybdate, 40-60 parts nickel sulfate, 30-90 parts ethanol, 15-21 parts organic passivating agent, 60-70 parts propyltrimethylsilane, 3-5 parts ZrB2-ZrC nanocomposite powder, 30-80 parts surfactant, and 500-1000 parts water.

2. The method for preparing a corrosion-resistant bolt according to claim 1, characterized in that, The preparation method of the ZrB2-ZrC nanocomposite powder includes the following steps: mixing zirconium powder and boron carbide, and then ball milling to obtain the ZrB2-ZrC nanocomposite powder.

3. The method for preparing a corrosion-resistant bolt according to claim 2, characterized in that, The molar ratio of zirconium powder to boron carbide is 3:1 to 1.

2.

4. The method for preparing a corrosion-resistant bolt according to claim 2, characterized in that, The ball mill rotates at a speed of 500-600 r / min, and the milling time is 32-35 h.

5. The method for preparing a corrosion-resistant bolt according to claim 2, characterized in that, The median particle size of the ZrB2-ZrC nanocomposite powder is 100~150 nm.

6. The method for preparing a corrosion-resistant bolt according to claim 1, characterized in that, The organic passivating agent includes 1-phenyl-5-mercaptotetrazole and / or hexamethylenediaminetetramethylenephosphonic acid.

7. The method for preparing a corrosion-resistant bolt according to claim 6, characterized in that, When the organic passivating agent is 1-phenyl-5-mercaptotetrazole and hexamethylenediaminetetramethylenephosphonic acid, the mass ratio of 1-phenyl-5-mercaptotetrazole to hexamethylenediaminetetramethylenephosphonic acid is 1:5~6.

8. The method for preparing a corrosion-resistant bolt according to claim 1, characterized in that, The passivation solution has a pH of 4-5; The passivation treatment temperature is 50~60℃; the passivation treatment time is 60~90s.

9. A method for preparing a corrosion-resistant bolt according to claim 1, characterized in that, The bolt body is composed of the following components by weight percentage: C 0.35%~0.45%, Mn 0.3%~0.65%, Cr 2.8%~3.5%, Ni 0.5%~1%, Al 0.5%~1.8%, Cu 0.3%~0.4%, Mo 0.15%~0.3%, Sb 0.02%~0.04%, P≤0.015%, S≤0.02%, with the remainder being Fe and other unavoidable impurities.

10. A corrosion-resistant bolt, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 9.

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