Antirust 42CrTi alloy steel as well as preparation method and application thereof

Abstract

The invention relates to the technical field of chromium-containing alloy steel, in particular to antirust 42CrTi alloy steel as well as a preparation method and application of the antirust 42CrTi alloy steel. 16 to 18 percent of Cr; 0.25 to 0.35 percent of Si; 1.8%-2% of Ni; 0.8% to 0.9% of Mo; 0.5 to 0.6 percent of V; 0.7%-1% of Mn; 0.012% to 0.018% of Ti; s is less than or equal to 0.025%; p is less than or equal to 0.03%; 0.03 to 0.04 percent of a nano particle reinforcing material; and the balance Fe and other impurities. The overall density difference between the nano-particle reinforced material and molten steel is reduced by regulating and controlling the components and the structure of the nano-particle reinforced material, and the core problem that the nano-particle reinforced material is difficult to uniformly disperse in the molten steel is avoided by a method of pre-synthesizing and then sintering a preform, so that the corrosion resistance, the hardness and the tensile strength of the alloy steel material are synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of chromium alloy steel technology, specifically to a rust-resistant 42CrTi alloy steel, its preparation method, and its application. Background Technology

[0002] 42Cr alloy steel, a common type of alloy steel, is widely used in high-strength fasteners such as bolts, nuts, connecting rods, and drive shafts. However, traditional high-chromium alloy steels are prone to corrosion under humid, salt spray, or acidic conditions, leading to premature failure of bolts and nuts. Simultaneously, with technological advancements, new requirements are being placed on the hardness and tensile strength of fastener materials to meet high load and friction / wear conditions. Current technologies often employ coatings or heat treatments for modification, but their effectiveness is limited and the processes are technically demanding. In recent years, nanotechnology has been introduced into alloy steel manufacturing. Commonly used nanoparticles include Al2O3, Cr3C2, WC, and TiC. Among these, TiC, with its excellent thermal stability, has been extensively studied; however, its density is only 4.25 g / cm³. 3 Its ratio with molten steel is 7.8 g / cm³. 3 The gap is significant. Using the traditional method of direct addition during melting and casting, TiC agglomeration is highly likely, resulting in poor dispersion of nanoparticles in the steel substrate and hindering the comprehensive improvement of performance. Therefore, an alloy steel material is needed that combines excellent rust resistance, high hardness, high tensile strength, and uniform nanoparticle dispersion. Summary of the Invention

[0003] The purpose of this invention is to provide a rust-resistant 42CrTi alloy steel, its preparation method, and its application. A nanoparticle-reinforced material with a special porous structure is prepared by a self-propagating high-temperature synthesis method. By controlling the composition and structure, the overall density difference between the nanoparticle-reinforced material and the molten steel is reduced. By using a pre-synthesized and then sintered preform method, the core problem of the nanoparticle-reinforced material being difficult to disperse uniformly in the molten steel is effectively avoided. This invention achieves a synergistic improvement in the corrosion resistance, hardness, and tensile strength of the alloy steel material.

[0004] The objective of this invention can be achieved through the following technical solution: a rust-resistant 42CrTi alloy steel, comprising the following weight percentages: C: 0.40-0.44%; Cr: 16-18%; Si: 0.25-0.35%; Ni: 1.8-2%; Mo: 0.8-0.9%; V: 0.5-0.6%; Mn: 0.7-1%; Ti: 0.012-0.018%; S≤0.025%; P≤0.03%; nanoparticle reinforcing material: 0.03-0.04%; the balance being Fe and other impurities.

[0005] A method for preparing rust-resistant 42CrTi alloy steel, comprising the following steps: Step S1: Mix Ni powder, Mo powder, nanoparticle reinforcing material, and Fe powder, transfer to a ball mill jar, and add anhydrous ethanol until completely covered. Ball mill for 10 hours at 80-100 rpm and a ball-to-material ratio of 10:1, with a 10-minute reversal time between rotations. Dry the mixture, add paraffin wax, and cold press it into a cylindrical green body at a pressure of 190-200 MPa for 4-5 minutes. The green body dimensions are Φ40mm × 2000mm. Sinter using a vacuum sintering process at a vacuum degree of 10... -2 At a temperature of 1400℃, the material was held for 90 minutes, then crushed to obtain a sintered preform, in which the mass fraction of paraffin was 3.8-4%. Step S2: Using a high-frequency induction furnace and a non-oxidizing steelmaking process, scrap steel, medium-carbon ferrochrome, ferrovanadium, and ferrotitanium are added to the furnace. When the temperature reaches 1550-1600℃, a sintering preform is added, and the temperature is held for 10-15 minutes. Slag is removed, deoxidation is performed, and the steel is tapped. After the molten steel is tapped from the furnace, it is poured into a ladle and then poured into a mold at a pouring temperature of 1480-1500℃ to obtain a 42CrTi alloy steel billet.

[0006] An application of a rust-resistant 42CrTi alloy steel, which can be used in bolts, nuts, connecting rods and drive shafts.

[0007] The application of a rust-resistant 42CrTi alloy steel in bolts includes the following steps: 42CrTi alloy steel billets are hot-rolled into bolt bars, then hot-worked into bolt blanks, and then heat-treated. After heat treatment, threads are machined to obtain 42CrTi alloy steel bolts. Furthermore, in its hot working process: the temperature is 900-920℃; in the heat treatment process: the quenching temperature is 850-880℃, the holding time is 30-40min, oil quenching to room temperature, the tempering temperature is 520-550℃, the holding time is 2-3h, and air cooling to room temperature.

[0008] The nanoparticle-reinforced material is prepared by the following steps: Step A1: Mix SiC whiskers with anhydrous ethanol and ultrasonically disperse for 8-10 min. Then add chromium nitrate nonahydrate and terephthalic acid. Stir at 120-150 rpm at room temperature for 25-30 min. Transfer to a reaction vessel and react at 210-220℃ for 7-8 h. Wash with N,N-dimethylformamide, wash with deionized water, dry, and grind to obtain SiC composite powder. Furthermore, in step A1: the ratio of SiC whiskers, anhydrous ethanol, chromium nitrate nonahydrate, and terephthalic acid is 0.75-0.8g: 45-50mL: 0.78-0.8g: 0.1-0.11g; Furthermore, the SiC whiskers used have a mass fraction greater than 99%, a diameter less than 2.5 μm, and an aspect ratio greater than 20; Step A2: Mix B4C powder and Ti powder and stir evenly, then add WO3 powder, Al powder and SiC composite material mixture, transfer to ball mill jar and add anhydrous ethanol until completely covered, ball mill for 24 hours at a speed of 80-100 rpm and a ball-to-material ratio of 4:1, with a forward and reverse rotation time of 10 minutes. After ball milling, dry and sieve to obtain mixed powder. Furthermore, in step A2: the mass ratio of B4C powder to Ti powder is 3:1, the mass ratio of WO3 powder to Al powder is 1:2, the mass ratio of (B4C powder + Ti powder) to (WO3 powder + Al powder) is 1:(1.4-1.7), and the mass fraction of SiC composite material in the total mass of the system is 1.2-1.4%; Furthermore, the B4C powder used has a mass fraction greater than 99.5% and a particle size less than 5 μm; the Ti powder has a mass fraction greater than 99.8% and a particle size less than 25 μm; the WO3 powder has a mass fraction greater than 99.5% and a particle size less than 40 μm; and the Al powder has a mass fraction greater than 99.5% and a particle size less than 15 μm. Step A3: Using a cold pressing process, the mixed powder is pressed into a cylindrical blank at a pressing pressure of 190-200MPa for 4-5 minutes. The blank size is Φ20mm×20mm. The blank is placed in an oven and kept at 220-240℃ for 2 hours. Then it is transferred to a centrifuge and subjected to a self-propagating high-temperature synthesis reaction initiated by tungsten wire at a speed of 1800rpm. After cooling to room temperature, it is crushed to obtain nanoparticle reinforced material.

[0009] Furthermore, in the reaction process for preparing nanoparticle-reinforced materials, SiC whiskers are first used as the matrix. A metal-organic framework structure is formed on the surface of the SiC whiskers using a hydrothermal method with chromium nitrate nonahydrate as the chromium source and terephthalic acid as the ligand, thus obtaining a SiC composite material. Then, B4C powder, Ti powder, WO3 powder, and Al powder are used as powder materials, and the SiC composite material is added as a structural aid. During the reaction process, the following reaction occurs: In the self-propagating high-temperature synthesis reaction, due to the "explosive combustion" mode of the reaction, a large amount of heat is released, causing Ti to melt first and surround the SiC composite material. As the molten Ti reacts with SiC, the generated Si partially melts and releases Si vapor, while some forms a Ti-Si solution with Ti. During the subsequent cooling process, due to the high melting point of TiC, it preferentially forms fine particles using the SiC composite material as a nucleation matrix. The presence of its whisker structure and surface metal-organic framework structure allows for the formation of a shell during nucleation and growth. At the same time, the further decomposition of SiC inside further promotes the growth of TiC, resulting in the formation of hollow tubes. The Ti-Si melt formed adheres to the TiC particles and continues to grow, resulting in a porous structure. Simultaneously, the release of a large amount of heat promotes the combination of free W and B. Due to the temperature gradient at the edges, C cools without being replaced, leading to the formation of WB inclusions. Since WC and TiC have the same lattice type and similar atomic sizes, a (Ti,W)C solid solution is formed. Because TiB2 and TiC have already grown completely, (Ti,W)C grows between TiB2 and TiC, thus producing a nanoparticle-reinforced material.

[0010] The beneficial effects of this invention are as follows: This invention discloses a rust-resistant 42CrTi alloy steel, its preparation method, and its application. A nanoparticle-reinforced material with a special porous structure is prepared by a self-propagating high-temperature synthesis method. By controlling the composition and structure, the overall density difference between the nanoparticle-reinforced material and the molten steel is reduced. By using a pre-synthesized and then sintered preform method, the core problem of the nanoparticle-reinforced material being difficult to disperse uniformly in the molten steel is effectively avoided. This achieves a synergistic improvement in the corrosion resistance, hardness, and tensile strength of the alloy steel material.

[0011] The alloy steel material prepared by this invention has a high chromium content, which ensures that the steel matrix itself has excellent passivation ability. The uniformly distributed nanoparticle reinforcing material further blocks the penetration path of corrosive media, forming a dual protection of "matrix + second phase", thus giving the alloy steel material excellent corrosion resistance. By using a pre-synthesis method to prepare nanoparticle reinforcing material with a porous hollow tubular structure, and by adding it to molten steel after sintering it into a preform, the problems of agglomeration and segregation caused by density difference are effectively solved. At the same time, the porous structure can also serve as a skeleton reinforcing phase. After it is immersed and penetrated into the molten steel, the difference in elasticity, plasticity and thermal properties between the matrix and the reinforcing phase leads to micro-region stress in the composite material, thereby enhancing the mechanical properties of the material. In addition, it can also work with the matrix to achieve a three-dimensional uniform distribution of nanoparticles in the steel matrix to improve the mechanical properties of the steel material. Detailed Implementation

[0012] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] Example 1 A rust-resistant 42CrTi alloy steel comprises the following weight percentages: C: 0.40%; Cr: 16%; Si: 0.25%; Ni: 1.8%; Mo: 0.8%; V: 0.5%; Mn: 0.7%; Ti: 0.012%; S≤0.025%; P≤0.03%; nanoparticle reinforcement: 0.03%; the balance being Fe and other impurities.

[0014] A method for preparing rust-resistant 42CrTi alloy steel, comprising the following steps: Step S1: Mix Ni powder, Mo powder, nanoparticle reinforcement material, and Fe powder, transfer to a ball mill jar, and add anhydrous ethanol until completely covered. Ball mill for 10 hours at 80 rpm and a ball-to-material ratio of 10:1, with a 10-minute reversal time between rotations. Dry the mixture, add paraffin wax, and cold press it into a cylindrical green body at a pressure of 190 MPa for 4 minutes. The green body dimensions are Φ40 mm × 2000 mm. Sinter using a vacuum sintering process at a vacuum degree of 10... -2 The material was heated to 1400℃ for 90 minutes, then crushed to obtain a sintered preform, in which the mass fraction of paraffin was 3.8%. Step S2: Using a high-frequency induction furnace and a non-oxidizing steelmaking process, scrap steel, medium-carbon ferrochrome, ferrovanadium, and ferrotitanium are added to the furnace. When the temperature reaches 1550℃, a sintering preform is added, and the furnace is held for 10 minutes. The slag is removed, the furnace is deoxidized, and the steel is tapped. The molten steel is poured into a ladle and then into a mold at a pouring temperature of 1480℃ to obtain a 42CrTi alloy steel billet.

[0015] An application of a rust-resistant 42CrTi alloy steel, which can be used in bolts, nuts, connecting rods and drive shafts.

[0016] The application of a rust-resistant 42CrTi alloy steel in bolts includes the following steps: 42CrTi alloy steel billets are hot-rolled into bolt bars, then hot-worked into bolt blanks, and then heat-treated. After heat treatment, threads are machined to obtain 42CrTi alloy steel bolts. Furthermore, in its hot working process: the temperature is 900℃; in the heat treatment process: the quenching temperature is 850℃, the holding time is 40min, the oil quenching is carried out to room temperature, the tempering temperature is 520℃, the holding time is 3h, and the air cooling is carried out to room temperature.

[0017] The nanoparticle-reinforced material is prepared by the following steps: Step A1: SiC whiskers and anhydrous ethanol were mixed and ultrasonically dispersed for 8 min. Then, chromium nitrate nonahydrate and terephthalic acid were added. The mixture was stirred for 25 min at a stirring rate of 150 rpm and room temperature. The mixture was then transferred to a reaction vessel and reacted at 210℃ for 7 h. The mixture was washed with N,N-dimethylformamide, deionized water, dried, and ground to obtain SiC composite powder. Furthermore, in step A1: the ratio of SiC whiskers, anhydrous ethanol, chromium nitrate nonahydrate, and terephthalic acid is 0.8g:45mL:0.78g:0.11g; Furthermore, the SiC whiskers used have a mass fraction greater than 99%, a diameter less than 2.5 μm, and an aspect ratio greater than 20; Step A2: Mix B4C powder and Ti powder and stir evenly, then add WO3 powder, Al powder and SiC composite material mixture, transfer to ball mill jar and add anhydrous ethanol until completely covered, ball mill for 24 hours at 80 rpm and ball-to-material ratio of 4:1, with the ball mill switching time being 10 min. After ball milling, dry and sieve to obtain mixed powder. Furthermore, in step A2: the mass ratio of B4C powder to Ti powder is 3:1, the mass ratio of WO3 powder to Al powder is 1:2, the mass ratio of (B4C powder + Ti powder) to (WO3 powder + Al powder) is 1:1.4, and the mass fraction of SiC composite material in the total mass of the system is 1.2%; Furthermore, the B4C powder used has a mass fraction greater than 99.5% and a particle size less than 5 μm; the Ti powder has a mass fraction greater than 99.8% and a particle size less than 25 μm; the WO3 powder has a mass fraction greater than 99.5% and a particle size less than 40 μm; and the Al powder has a mass fraction greater than 99.5% and a particle size less than 15 μm. Step A3: Using a cold pressing process, the mixed powder is pressed into a cylindrical blank at a pressing pressure of 200MPa for 4 minutes. The blank size is Φ20mm×20mm. The blank is placed in an oven and kept at 220℃ for 2 hours. Then it is transferred to a centrifuge and subjected to a self-propagating high-temperature synthesis reaction initiated by tungsten wire at a speed of 1800rpm. After cooling to room temperature, it is crushed to obtain nanoparticle reinforced material.

[0018] Example 2 A rust-resistant 42CrTi alloy steel comprises the following weight percentages: C: 0.44%; Cr: 16%; Si: 0.25%; Ni: 2%; Mo: 0.8%; V: 0.5%; Mn: 1%; Ti: 0.012%; S≤0.025%; P≤0.03%; nanoparticle reinforcement: 0.04%; the balance being Fe and other impurities.

[0019] A method for preparing rust-resistant 42CrTi alloy steel, comprising the following steps: Step S1: Mix Ni powder, Mo powder, nanoparticle reinforcing material, and Fe powder, transfer to a ball mill jar, and add anhydrous ethanol until completely covered. Ball mill for 10 hours at 100 rpm and a ball-to-material ratio of 10:1, with a 10-minute reversal time between rotations. Dry the mixture, add paraffin wax, and cold press it into a cylindrical green body at a pressure of 190 MPa for 4 minutes. The green body dimensions are Φ40 mm × 2000 mm. Sinter using a vacuum sintering process at a vacuum degree of 10... -2 The material was heated to 1400℃ for 90 minutes, then crushed to obtain a sintered preform, in which the mass fraction of paraffin was 3.8%. Step S2: Using a high-frequency induction furnace and non-oxidizing steelmaking process, scrap steel, medium carbon ferrochrome, ferrovanadium, and ferrotitanium are added to the furnace. When the temperature reaches 1550℃, sintering preforms are added, and the temperature is held for 15 minutes. Slag is removed, deoxidation is performed, and the steel is tapped. After the molten steel is tapped from the furnace, it is poured into a ladle and then poured into a mold at a pouring temperature of 1480-1500℃ to obtain 42CrTi alloy steel billets.

[0020] An application of a rust-resistant 42CrTi alloy steel, which can be used in bolts, nuts, connecting rods and drive shafts.

[0021] The application of a rust-resistant 42CrTi alloy steel in bolts includes the following steps: 42CrTi alloy steel billets are hot-rolled into bolt bars, then hot-worked into bolt blanks, and then heat-treated. After heat treatment, threads are machined to obtain 42CrTi alloy steel bolts. Furthermore, in its hot working process: the temperature is 900℃; in the heat treatment process: the quenching temperature is 850℃, the holding time is 30min, the oil quenching is brought to room temperature, the tempering temperature is 520℃, the holding time is 2h, and the air cooling is brought to room temperature.

[0022] The nanoparticle-reinforced material is prepared by the following steps: Step A1: SiC whiskers and anhydrous ethanol were mixed and ultrasonically dispersed for 8 min. Chromium nitrate nonahydrate and terephthalic acid were then added. The mixture was stirred for 25 min at a stirring rate of 120 rpm and room temperature. The mixture was then transferred to a reaction vessel and reacted at 210℃ for 7 h. The mixture was washed with N,N-dimethylformamide and deionized water, dried, and ground to obtain SiC composite powder. Furthermore, in step A1: the ratio of SiC whiskers, anhydrous ethanol, chromium nitrate nonahydrate, and terephthalic acid is 0.75g:45mL:0.78g:0.1g; Furthermore, the SiC whiskers used have a mass fraction greater than 99%, a diameter less than 2.5 μm, and an aspect ratio greater than 20; Step A2: Mix B4C powder and Ti powder and stir evenly, then add WO3 powder, Al powder and SiC composite material mixture, transfer to ball mill jar and add anhydrous ethanol until completely covered, ball mill for 24 hours at 80 rpm and ball-to-material ratio of 4:1, with the ball mill switching time being 10 min. After ball milling, dry and sieve to obtain mixed powder. Furthermore, in step A2: the mass ratio of B4C powder to Ti powder is 3:1, the mass ratio of WO3 powder to Al powder is 1:2, the mass ratio of (B4C powder + Ti powder) to (WO3 powder + Al powder) is 1:1.4, and the mass fraction of SiC composite material in the total mass of the system is 1.2%; Furthermore, the B4C powder used has a mass fraction greater than 99.5% and a particle size less than 5 μm; the Ti powder has a mass fraction greater than 99.8% and a particle size less than 25 μm; the WO3 powder has a mass fraction greater than 99.5% and a particle size less than 40 μm; and the Al powder has a mass fraction greater than 99.5% and a particle size less than 15 μm. Step A3: Using a cold pressing process, the mixed powder is pressed into a cylindrical blank at a pressing pressure of 190-200MPa for 4 minutes. The blank size is Φ20mm×20mm. The blank is placed in an oven and kept at 220℃ for 2 hours. Then it is transferred to a centrifuge and subjected to a self-propagating high-temperature synthesis reaction initiated by tungsten wire at a speed of 1800rpm. After cooling to room temperature, it is crushed to obtain nanoparticle reinforced material.

[0023] Example 3 A rust-resistant 42CrTi alloy steel comprises the following weight percentages: C: 0.42%; Cr: 18%; Si: 0.35%; Ni: 2%; Mo: 0.9%; V: 0.6%; Mn: 1%; Ti: 0.018%; S≤0.025%; P≤0.03%; nanoparticle reinforcement: 0.04%; the balance being Fe and other impurities.

[0024] A method for preparing rust-resistant 42CrTi alloy steel, comprising the following steps: Step S1: Mix Ni powder, Mo powder, nanoparticle reinforcing material, and Fe powder, transfer to a ball mill jar, and add anhydrous ethanol until completely covered. Ball mill for 10 hours at 100 rpm and a ball-to-material ratio of 10:1, with a 10-minute reversal time between cycles. Dry the mixture, add paraffin wax, and cold press it into a cylindrical green body at a pressure of 200 MPa for 4-5 minutes. The green body dimensions are Φ40mm × 2000mm. Sinter using a vacuum sintering process at a vacuum degree of 10... -2 The material was subjected to a temperature of 1400℃ for 90 minutes, then crushed to obtain a sintered preform, wherein the mass fraction of paraffin was 4%. Step S2: Using a high-frequency induction furnace and a non-oxidizing steelmaking process, scrap steel, medium-carbon ferrochrome, ferrovanadium, and ferrotitanium are added to the furnace. When the temperature reaches 1600℃, a sintering preform is added, and the furnace is held for 15 minutes. The slag is removed, the steel is deoxidized, and then tapped. The molten steel is poured into a ladle and then into a mold at a pouring temperature of 1500℃ to obtain a 42CrTi alloy steel billet.

[0025] An application of a rust-resistant 42CrTi alloy steel, which can be used in bolts, nuts, connecting rods and drive shafts.

[0026] The application of a rust-resistant 42CrTi alloy steel in bolts includes the following steps: 42CrTi alloy steel billets are hot-rolled into bolt bars, then hot-worked into bolt blanks, and then heat-treated. After heat treatment, threads are machined to obtain 42CrTi alloy steel bolts. Furthermore, in its hot working process: the temperature is 920℃; in its heat treatment: the quenching temperature is 880℃, the holding time is 40min, the oil quenching is carried out to room temperature, the tempering temperature is 550℃, the holding time is 3h, and the air cooling is carried out to room temperature.

[0027] The nanoparticle-reinforced material is prepared by the following steps: Step A1: SiC whiskers and anhydrous ethanol were mixed and ultrasonically dispersed for 10 min. Then, chromium nitrate nonahydrate and terephthalic acid were added. The mixture was stirred for 30 min at a stirring rate of 150 rpm and room temperature. The mixture was then transferred to a reaction vessel and reacted at 220℃ for 8 h. The mixture was washed with N,N-dimethylformamide, washed with deionized water, dried, and ground to obtain SiC composite powder. Furthermore, in step A1: the ratio of SiC whiskers, anhydrous ethanol, chromium nitrate nonahydrate, and terephthalic acid is 0.8g:50mL:0.8g:0.11g; Furthermore, the SiC whiskers used have a mass fraction greater than 99%, a diameter less than 2.5 μm, and an aspect ratio greater than 20; Step A2: Mix B4C powder and Ti powder and stir evenly, then add WO3 powder, Al powder and SiC composite material mixture, transfer to ball mill jar and add anhydrous ethanol until completely covered, ball mill for 24 hours at 100 rpm and ball-to-material ratio of 4:1, with the ball mill switching time being 10 min. After ball milling, dry and sieve to obtain mixed powder. Furthermore, in step A2: the mass ratio of B4C powder to Ti powder is 3:1, the mass ratio of WO3 powder to Al powder is 1:2, the mass ratio of (B4C powder + Ti powder) to (WO3 powder + Al powder) is 1:1.7, and the mass fraction of SiC composite material in the total mass of the system is 1.4%. Furthermore, the B4C powder used has a mass fraction greater than 99.5% and a particle size less than 5 μm; the Ti powder has a mass fraction greater than 99.8% and a particle size less than 25 μm; the WO3 powder has a mass fraction greater than 99.5% and a particle size less than 40 μm; and the Al powder has a mass fraction greater than 99.5% and a particle size less than 15 μm. Step A3: Using a cold pressing process, the mixed powder is pressed into a cylindrical blank at a pressing pressure of 200MPa for 5 minutes. The blank size is Φ20mm×20mm. The blank is placed in an oven and kept at 240℃ for 2 hours. Then it is transferred to a centrifuge and subjected to a self-propagating high-temperature synthesis reaction initiated by tungsten wire at a speed of 1800rpm. After cooling to room temperature, it is crushed to obtain nanoparticle reinforced material.

[0028] Comparative Example 1 Compared with Example 3, this comparative example replaces the nanoparticle reinforcing material in the preparation process of 442CrTi alloy steel in Example 3 with TiC particles, while the other steps are the same. The mass fraction of TiC particles is greater than 99.5%, and the particle size is less than 3 μm.

[0029] Comparative Example 2 Compared with Example 3, this comparative example removes the SiC composite powder in the preparation process of nanoparticle-reinforced material in Example 3, while the other steps are the same.

[0030] Comparative Example 3 Compared with Example 3, this comparative example removes the nanoparticle-reinforcing material from Example 3, while the other steps are the same.

[0031] The 42CrTi alloy steel bolts prepared in Examples 1, 2, 3, Comparative Examples 1, 2, and 3 were used. Their tensile strength, yield strength, elongation, reduction of area, and hardness were measured according to GB / T 228.1-2021 and GB / T 3098.1-2010 at a test temperature of 20℃. A corrosion salt solution was prepared according to GB / T 10125-2012, with a NaCl concentration of 50 g / L, a CuCl2 concentration of 0.3 g / L, and glacial acetic acid added to adjust the pH to 3.5. Corrosion performance was then tested using continuous spraying, with the rust appearance time observed and recorded every 10 hours. The test results are shown in Table 1 below. Table 1 Test Results Testing items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength (MPa) 1537 1563 1581 1336 1404 1283 Yield strength (MPa) 1372 1402 1414 1213 1278 1116 Elongation (%) 11.21 11.52 11.71 10.44 11.03 10.21 Area shrinkage rate (%) 51.57 52.35 52.65 45.39 48.11 41.37 Hardness (HRC) 45.8 46.1 46.2 41.3 43.6 40.7 Time of rust appearance (h) >1500 >1500 >1500 970 1100 850 As shown in the table, the test results indicate that, compared with Comparative Examples 1, 2, and 3, Examples 1-3 show a significant improvement in various properties compared to Comparative Example 3 without nanoparticle reinforcement, and their performance meets the requirements for grade 14.9 bolts. In Comparative Example 1, the nanoparticle reinforcement was replaced with TiC particles. However, TiC is more prone to agglomeration in molten steel than the nanoparticle reinforcement of this invention, leading to a significant decrease in material performance. In Comparative Example 2, the SiC composite powder was removed during the preparation of the nanoparticle reinforcement in Example 3. Due to the absence of SiC composite powder, the self-propagating combustion synthesis process lacks a template with SiC whiskers, preventing the formation of a special porous hollow tubular structure. Consequently, the material partially agglomerates during subsequent molten steel pouring, affecting its mechanical properties and corrosion resistance.

[0032] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A rust-resistant 42CrTi alloy steel, characterized in that: Includes the following weight percentages: C: 0.40-0.44%; Cr: 16-18%; Si: 0.25-0.35%; Ni: 1.8-2%; Mo: 0.8-0.9%; V: 0.5-0.6%; Mn: 0.7-1%; Ti: 0.012-0.018%; S≤0.025%; P≤0.03%; Nanoparticle reinforced material: 0.03-0.04%; Balance is Fe and other impurities.

2. The method for preparing a rust-resistant 42CrTi alloy steel as described in claim 1, characterized in that, Includes the following steps: Step S1: Mix Ni powder, Mo powder, nanoparticle reinforcing material, and Fe powder, transfer to a ball mill jar, and add anhydrous ethanol until completely covered. Ball mill for 10 hours at 80-100 rpm and a ball-to-material ratio of 10:1, with a 10-minute reversal time between rotations. Dry the mixture, add paraffin wax, and cold press it into a cylindrical green body at a pressure of 190-200 MPa for 4-5 minutes. The green body dimensions are Φ40mm × 2000mm. Sinter using a vacuum sintering process at a vacuum degree of 10... -2 At a temperature of 1400℃, the material was held for 90 minutes, then crushed to obtain a sintered preform, in which the mass fraction of paraffin was 3.8-4%. Step S2: Using a high-frequency induction furnace and a non-oxidizing steelmaking process, scrap steel, medium-carbon ferrochrome, ferrovanadium, and ferrotitanium are added to the furnace. When the temperature reaches 1550-1600℃, a sintering preform is added, and the temperature is held for 10-15 minutes. Slag is removed, deoxidation is performed, and the steel is tapped. After the molten steel is tapped from the furnace, it is poured into a ladle and then poured into a mold at a pouring temperature of 1480-1500℃ to obtain a 42CrTi alloy steel billet.

3. The method for preparing a rust-resistant 42CrTi alloy steel according to claim 2, characterized in that: The nanoparticle-reinforced material is prepared by the following steps: Step A1: Mix SiC whiskers with anhydrous ethanol and ultrasonically disperse for 8-10 min. Then add chromium nitrate nonahydrate and terephthalic acid. Stir at 120-150 rpm at room temperature for 25-30 min. Transfer to a reaction vessel and react at 210-220℃ for 7-8 h. Wash with N,N-dimethylformamide, wash with deionized water, dry, and grind to obtain SiC composite powder. Step A2: Mix B4C powder and Ti powder and stir evenly, then add WO3 powder, Al powder and SiC composite material mixture, transfer to ball mill jar and add anhydrous ethanol until completely covered, ball mill for 24 hours at a speed of 80-100 rpm and a ball-to-material ratio of 4:1, with a forward and reverse rotation time of 10 minutes. After ball milling, dry and sieve to obtain mixed powder. Step A3: Using a cold pressing process, the mixed powder is pressed into a cylindrical blank at a pressing pressure of 190-200MPa for 4-5 minutes. The blank size is Φ20mm×20mm. The blank is placed in an oven and kept at 220-240℃ for 2 hours. Then it is transferred to a centrifuge and subjected to a self-propagating high-temperature synthesis reaction initiated by tungsten wire at a speed of 1800rpm. After cooling to room temperature, it is crushed to obtain nanoparticle reinforced material.

4. The method for preparing a rust-resistant 42CrTi alloy steel according to claim 3, characterized in that: In step A1: the ratio of SiC whiskers, anhydrous ethanol, chromium nitrate nonahydrate, and terephthalic acid is 0.75-0.8g: 45-50mL: 0.78-0.8g: 0.1-0.11g; The SiC whiskers used have a mass fraction greater than 99%, a diameter less than 2.5 μm, and an aspect ratio greater than 20.

5. The method for preparing a rust-resistant 42CrTi alloy steel according to claim 3, characterized in that: In step A2: the mass ratio of B4C powder to Ti powder is 3:1, the mass ratio of WO3 powder to Al powder is 1:2, the ratio between the total mass of B4C powder and Ti powder and the total mass of WO3 powder and Al powder is 1:(1.4-1.7), and the mass fraction of SiC composite material in the total mass of the system is 1.2-1.4%. The B4C powder has a purity greater than 99.5% and a particle size less than 5 μm; the Ti powder has a purity greater than 99.8% and a particle size less than 25 μm; the WO3 powder has a purity greater than 99.5% and a particle size less than 40 μm; and the Al powder has a purity greater than 99.5% and a particle size less than 15 μm.

6. Applying the rust-resistant 42CrTi alloy steel according to any one of claims 1-5 to bolts, nuts, connecting rods, and drive shafts, characterized in that: The application of the rust-resistant 42CrTi alloy steel in bolts includes the following steps: 42CrTi alloy steel billets are hot-rolled into bolt bars, then hot-worked into bolt blanks, and then heat-treated. After heat treatment, threads are machined to obtain 42CrTi alloy steel bolts. During the heat treatment, the temperature is 900-920℃; In the heat treatment: the quenching temperature is 850-880℃, the holding time is 30-40min, the oil quenching is carried out to room temperature, the tempering temperature is 520-550℃, the holding time is 2-3h, and the air cooling is carried out to room temperature.