Preparation process of wear-resistant cold-drawn section steel

Abstract

The invention relates to the technical field of profile steel preparation, in particular to a preparation process of wear-resistant cold-drawn profile steel, which comprises the following steps: selecting high-carbon alloy steel with specific components as a raw material, carrying out deep impurity removal, grain refinement and homogenization treatment on the raw material, and adopting a multi-stage cold-drawing deformation process to obtain the wear-resistant cold-drawn profile steel. A hard alloy mold with a nanoscale tungsten carbide-titanium carbide-aluminum oxide-silicon nitride composite wear-resistant coating is used for forming steel, and vacuum quenching and low-temperature tempering treatment are conducted on the steel subjected to cold drawing forming; the method has the beneficial effects that the yield point strength, the tensile strength, the hardness and the corrosion resistance of the steel are remarkably improved through the cold drawing process. And plastic deformation in the cold drawing process enables the internal structure of the steel to be more compact and grains to be refined, so that the comprehensive mechanical property of the steel is improved.

Description

Technical Field

[0001] The invention relates to the field of section steel preparation, in particular to a preparation process of wear-resistant cold-drawn section steel. Background Art

[0002] Cold-drawn steel is a type of steel produced by the cold-drawing process, which has excellent mechanical properties and a wide range of applications. However, in the production process of cold-drawn steel, there are some technical challenges.

[0003] The quality of raw materials directly impacts the final performance of cold-drawn steel. Therefore, selecting the right raw materials and pre-treating them is crucial. For example, impurities such as scale and oil on the steel surface can affect the steel's plasticity and the cold-drawing effect, requiring effective removal. Controlling process parameters during the cold-drawing process is also crucial. Parameters such as the cold-drawing rate, cold-drawing stress, and deformation rate require precise control to ensure uniform plastic deformation during the cold-drawing process, thereby improving its strength and hardness. Different steel materials and shapes and sizes may require different cold-drawing process parameters. Die design and manufacture are also crucial steps in cold-drawn steel production. The die's shape and precision directly impact the final shape and size of the cold-drawn steel. Furthermore, the die's wear resistance and service life are also factors to consider.

[0004] In the subsequent processing of cold-drawn steel, heat treatment, straightening, cutting, inspection, and packaging are also crucial. Heat treatment eliminates internal stresses during the cold drawing process and improves the steel's toughness and ductility; straightening ensures the steel's straightness and dimensional accuracy; cutting meets the length requirements of different customers; inspection ensures that the steel's quality meets standard requirements; and packaging facilitates its transportation and sales. With the continuous advancement of industrial technology, the performance and quality requirements for cold-drawn steel are becoming increasingly demanding. Traditional cold-drawn steel production processes are no longer able to meet market demand, necessitating the development of new production processes and technologies to improve the performance and quality of cold-drawn steel. Summary of the Invention

[0005] The object of the present invention is to provide a preparation process of wear-resistant cold-drawn steel to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a preparation process of wear-resistant cold-drawn steel, the preparation process comprising the following steps: High-carbon alloy steel with a specific composition is selected as the raw material. The high-carbon alloy steel contains, by weight percentage, the following: carbon 0.95%-1.05%, chromium 1.4%-1.6%, molybdenum 0.5%-0.6%, vanadium 0.25%-0.35%, nickel 0.15%-0.25%, boron 0.001%-0.005%, and the balance is iron and unavoidable impurities; Deep impurity removal, grain refinement and homogenization treatment of raw materials, including pickling, sandblasting, ultrasonic cleaning, rapid heating to austenitizing temperature followed by rapid cooling to refine grains, and long-term holding at a specific temperature to homogenize the structure; A multi-stage cold drawing process is used, including rough drawing, intermediate drawing and finish drawing, with specific cold drawing rate, cold drawing stress, deformation speed and lubrication conditions set for each stage; The steel is formed using a cemented carbide die with a nano-scale tungsten carbide-titanium carbide-aluminum oxide-silicon nitride composite wear-resistant coating. Graphene is added to the coating to enhance the bonding strength and toughness of the coating to the substrate. The cold-drawn steel is vacuum quenched and low-temperature tempered. The quenching medium is specially purified high-pressure nitrogen. The variable temperature tempering process is used during the tempering process to optimize the microstructure and properties.

[0007] Preferably, the pickling step in the deep impurity removal treatment uses a hydrochloric acid solution with a concentration of 19%-20%, soaking at room temperature for 1.8-2 hours, and assisted by ultrasonic vibration to completely remove the oxide scale and rust on the surface of the raw material.

[0008] Preferably, in the multi-stage cold drawing deformation process, the cold drawing rate in the rough drawing stage is 28%-30%, the cold drawing rate in the intermediate drawing stage is 13%-14%, and the cold drawing rate in the fine drawing stage is 7%-8%. The cold drawing stress in each stage is precisely set according to the material of the steel and the required finished product size. The deformation speed is controlled at 8-12 mm / s, and special lubricants are used to reduce friction and wear.

[0009] Preferably, the wear-resistant coating thickness of the cemented carbide mold with a nano-scale tungsten carbide-titanium carbide-aluminum oxide-silicon nitride composite wear-resistant coating is 10-15 nanometers, wherein the weight ratio of tungsten carbide, titanium carbide, aluminum oxide and silicon nitride is 4:2:1:1 to 5:2:1:1, and the amount of graphene added is 0.5%-1.5% of the total weight of the coating to improve the wear resistance, hardness and thermal shock resistance of the mold.

[0010] Preferably, the temperature of the vacuum quenching treatment is 830-840 degrees Celsius, the holding time is 1.8-2.2 hours, and the quenching medium is specially purified high-pressure nitrogen with a pressure of 3-4 MPa to ensure that the steel obtains a uniform and refined martensitic structure.

[0011] Preferably, the low temperature tempering treatment adopts a variable temperature tempering process, first keeping the temperature at 180-190 degrees Celsius for 2 hours, and then keeping the temperature at 200-210 degrees Celsius for 1 hour, so as to maintain the high hardness, good toughness and resistance to temper brittleness of the steel.

[0012] Preferably, before the cold drawing deformation step, the raw materials are preheated at a temperature of 630-640 degrees Celsius and a holding time of 1-1.25 hours to improve the plasticity of the steel and reduce the cold drawing deformation resistance, while promoting the dissolution and uniform distribution of microalloying elements.

[0013] Preferably, after the mold forming step, the cold-drawn steel is subjected to ultra-smooth surface polishing using diamond grinding paste with a particle size of W0.25-W0.5, supplemented by electrolytic polishing technology, to improve its surface finish, reduce the friction coefficient and enhance wear resistance.

[0014] Preferably, the surface residual stress elimination and strengthening treatment of the cold-drawn steel is performed before vacuum quenching treatment, by high-frequency induction heating and subsequent rapid cooling to reduce the surface residual tensile stress, improve the surface hardness and fatigue resistance.

[0015] Preferably, after the low-temperature tempering treatment, the cold-drawn steel is also subjected to comprehensive performance testing and evaluation, including hardness testing, toughness testing, wear resistance testing, fatigue strength testing and corrosion performance testing, to ensure that its comprehensive performance meets the design requirements, and qualified products are packaged, labeled and traced, and detailed product performance reports and instruction manuals are provided.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a process for preparing wear-resistant cold-drawn steel. Through the cold-drawing process, the steel's yield point strength, tensile strength, hardness, and corrosion resistance are significantly improved. The plastic deformation during the cold-drawing process densifies the steel's internal structure and refines its grain size, thereby improving its overall mechanical properties. The heat treatment process further eliminates internal stresses during the cold-drawing process, enhancing the steel's toughness and plasticity, making it more reliable in various environments.

[0017] The cold-drawing process utilizes the plastic deformation properties of steel to mechanically stretch the steel to the desired shape and size, eliminating the need for extensive cutting, thus significantly saving material costs. Furthermore, the high dimensional accuracy of cold-drawn steel reduces material loss during subsequent processing, further reducing production costs.

[0018] The production process for cold-drawn steel is relatively simple, making it easy to automate and scale production. By optimizing the production process and equipment configuration, production efficiency can be significantly improved and cycle times shortened. Furthermore, special-shaped cold-drawn steel products can be formed directly through dies, eliminating the need for complex machining, further improving production efficiency.

[0019] Cold-drawn steel, with its excellent mechanical and processing properties, is widely used in a variety of fields, including machinery and equipment, automotive manufacturing, hardware tools, and construction machinery. With the continuous advancement of industrial technology, the application areas of cold-drawn steel will continue to expand. For example, in wind and hydropower generation, cold-drawn steel is used to manufacture key generator components, such as shafts and blades. Its excellent mechanical properties and corrosion resistance significantly improve the performance and lifespan of generators.

[0020] Strict quality control and inspection processes ensure that cold-drawn steel meets standard requirements. Precision mold design and manufacturing also guarantee dimensional accuracy and surface quality. High-quality cold-drawn steel not only improves product reliability and service life, but also reduces maintenance costs and risks for customers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0022] In order to clearly and completely describe the objectives and technical solutions of the present invention and make the advantages more clearly understood, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, not all of them, and are only used to explain the embodiments of the present invention, not to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] In the first embodiment, the present invention provides a technical solution: a preparation process of wear-resistant cold-drawn steel, the preparation process comprising the following steps: Raw material selection: High carbon alloy steel is selected as the raw material, which contains, by weight percentage, the following: carbon 0.98%, chromium 1.5%, molybdenum 0.55%, vanadium 0.3%, nickel 0.2%, boron 0.003%, and the balance is iron and inevitable impurities.

[0024] Raw material pretreatment: Acid pickling: Use a 19.5% hydrochloric acid solution to soak the raw materials at room temperature for 2 hours, supplemented by ultrasonic vibration to thoroughly remove scale and rust.

[0025] Sand blasting: Use fine sand to blast the surface of the raw material to further remove surface impurities and increase surface roughness.

[0026] Ultrasonic cleaning: Place the raw materials in an ultrasonic cleaning machine and clean them with clean water to remove residues.

[0027] Grain refinement and homogenization: Rapidly heat the raw material to austenitizing temperature (approximately 850°C), hold for a period of time, and then quench to refine the grains. Then, hold at 600°C for 4 hours to homogenize the structure.

[0028] Multi-stage cold drawing: Rough drawing: Set the cold drawing rate to 29%, adjust the cold drawing stress according to the steel material, control the deformation speed at 10mm / s, and use a special lubricant. Intermediate drawing: Set the cold drawing rate to 13.5%, adjust the cold drawing stress, and maintain a stable deformation speed. Finishing drawing: Set the cold drawing rate to 7.5%, and precisely control the cold drawing stress and deformation speed to ensure the dimensional accuracy of the finished product.

[0029] Mold Forming: Steel is molded using a cemented carbide mold coated with a nanoscale wear-resistant composite coating of tungsten carbide, titanium carbide, aluminum oxide, and silicon nitride. The coating is 12 nanometers thick and contains a weight ratio of tungsten carbide, titanium carbide, aluminum oxide, and silicon nitride of 4.5:2:1:1. The graphene content is 1% of the total coating weight.

[0030] Heat Treatment: Vacuum Quenching: The formed steel is placed in a vacuum furnace, heated to 835 degrees Celsius, held at this temperature for 2 hours, and then quenched using specially purified high-pressure nitrogen at a pressure of 3.5 MPa. Low-Tempering: A variable temperature tempering process is used, first holding at 185 degrees Celsius for 2 hours, then at 205 degrees Celsius for 1 hour.

[0031] Subsequent treatment: Ultra-smooth surface polishing: Use diamond grinding paste with a particle size of W0.5, supplemented by electrolytic polishing technology to improve the surface finish. Performance testing and evaluation: Conduct comprehensive performance testing, including hardness, toughness, wear resistance, fatigue strength and corrosion performance testing.

[0032] Packaging, labeling and traceability management: Qualified products are packaged and labeled with traceability information.

[0033] In the second embodiment, the present invention provides a technical solution: a preparation process of wear-resistant cold-drawn steel, the preparation process comprising the following steps: Raw material selection: Select high carbon alloy steel, the composition of which is the same as that in Example 1.

[0034] Raw material pretreatment: Pickling: Soak in 20% hydrochloric acid for 2 hours, supplemented by ultrasonic vibration. Sandblasting and ultrasonic cleaning: Same as in Example 1. Grain refinement and homogenization: Rapidly heat to 860°C, then quench to refine the grains. Hold at 610°C for 3.5 hours to homogenize the structure.

[0035] Multi-stage cold drawing: Rough drawing stage: cold drawing rate 30%, other conditions are the same as Example 1. Intermediate drawing stage: cold drawing rate 14%, cold drawing stress is adjusted to maintain a stable deformation rate. Finishing drawing stage: cold drawing rate 8%, precise control of conditions to ensure dimensional accuracy.

[0036] Mold molding: The same mold as in Example 1 was used for molding, with a coating thickness of 13 nm and a graphene addition amount of 0.8%.

[0037] Heat treatment: Vacuum quenching: 840 degrees Celsius, hold for 1.8 hours, quenched with 3MPa purified high-pressure nitrogen. Low-temperature tempering: variable temperature tempering, hold for 2 hours at 190 degrees Celsius, hold for 0.5 hours at 210 degrees Celsius.

[0038] Subsequent treatment: Surface ultra-smooth polishing: using W0.25 diamond grinding paste, electrolytic polishing. Performance testing, packaging, labeling and traceability management: the same as in Example 1.

[0039] In a third embodiment, the present invention provides a technical solution: a preparation process of wear-resistant cold-drawn steel, the preparation process comprising the following steps: Raw material selection: high carbon alloy steel was selected. The composition was slightly different from that in Example 1, with a carbon content of 1.02% and the contents of other elements being the same.

[0040] Raw material pretreatment: Pickling: Use 19% hydrochloric acid solution, soak for 1.8 hours, and ultrasonic vibration. Sandblasting and ultrasonic cleaning: Same as in Example 1. Grain refinement and homogenization: Heat to 855°C, quench, and hold at 620°C for 3 hours.

[0041] Multi-stage cold drawing deformation: Rough drawing stage: cold drawing rate 28%, other conditions are the same as Example 1. Intermediate drawing stage: cold drawing rate 13%, adjust stress and maintain speed. Finishing drawing stage: cold drawing rate 7%, precise control.

[0042] Mold molding: A mold similar to that in Example 1 was used, with a coating thickness of 10 nm and no graphene added.

[0043] Heat treatment: Vacuum quenching: 830 degrees Celsius, hold for 2.2 hours, quench using 4MPa purified high-pressure nitrogen. Low-temperature tempering: 180 degrees Celsius, hold for 2.5 hours, 200 degrees Celsius, hold for 1 hour.

[0044] Subsequent processing: Surface polishing: Use W1 diamond grinding paste, non-electrolytic polishing. Performance testing, packaging, labeling and traceability management: Same as Example 1.

[0045] In a fourth embodiment, the present invention provides a technical solution: a preparation process of wear-resistant cold-drawn steel, the preparation process comprising the following steps: Raw material selection: high carbon alloy steel was selected, the composition of which was similar to that of Example 1, but the boron content was 0.005%.

[0046] Raw material pretreatment: Pickling: Use 20% hydrochloric acid solution, soak for 2 hours, and ultrasonic vibration. Sandblasting and ultrasonic cleaning: Same as in Example 1. Grain refinement and homogenization: Heat to 865°C, quench, and hold at 630°C for 2.5 hours.

[0047] Multi-stage cold drawing deformation: Rough drawing stage: cold drawing rate 29.5%, other conditions are the same as Example 1. Intermediate drawing stage: cold drawing rate 12.5%, adjust stress and maintain speed. Finishing drawing stage: cold drawing rate 6.5%, precise control.

[0048] Mold molding: The same mold as in Example 1 was used, with a coating thickness of 15 nm and a graphene addition amount of 1.5%.

[0049] Heat treatment: Vacuum quenching: 838 degrees Celsius, hold for 2 hours, quench with 3.2MPa purified high-pressure nitrogen. Low-temperature tempering: variable temperature tempering, hold at 185 degrees Celsius for 1.5 hours, hold at 205 degrees Celsius for 1.5 hours.

[0050] Subsequent processing: Ultra-smooth surface polishing: Use W0.3 diamond grinding paste and electrolytic polishing. Performance testing: Add salt spray testing to the corrosion resistance test. Packaging, labeling, and traceability management: Same as Example 1, but with an additional corrosion resistance test report.

[0051] Examples 1 through 4 demonstrate different variations of the wear-resistant cold-drawn steel production process. Each step is detailed to ensure process integrity and repeatability. By adjusting the raw material composition, pretreatment conditions, cold-drawing deformation parameters, die coating, heat treatment process, and subsequent processing steps, wear-resistant cold-drawn steel with different performance characteristics can be produced.

[0052] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing wear-resistant cold-drawn steel, characterized by: The preparation process comprises the following steps: High-carbon alloy steel with a specific composition is selected as the raw material. The high-carbon alloy steel contains, by weight percentage, the following: carbon 0.95%-1.05%, chromium 1.4%-1.6%, molybdenum 0.5%-0.6%, vanadium 0.25%-0.35%, nickel 0.15%-0.25%, boron 0.001%-0.005%, and the balance is iron and unavoidable impurities; Deep impurity removal, grain refinement and homogenization treatment of raw materials, including pickling, sandblasting, ultrasonic cleaning, rapid heating to austenitizing temperature followed by rapid cooling to refine grains, and long-term holding at a specific temperature to homogenize the structure; A multi-stage cold drawing process is used, including rough drawing, intermediate drawing and finish drawing, with specific cold drawing rate, cold drawing stress, deformation speed and lubrication conditions set for each stage; The steel is formed using a cemented carbide die with a nano-scale tungsten carbide-titanium carbide-aluminum oxide-silicon nitride composite wear-resistant coating. Graphene is added to the coating to enhance the bonding strength and toughness of the coating to the substrate. The cold-drawn steel is vacuum quenched and low-temperature tempered. The quenching medium is specially purified high-pressure nitrogen. The variable temperature tempering process is used during the tempering process to optimize the microstructure and properties.

2. The process for preparing wear-resistant cold-drawn steel according to claim 1, characterized in that: The pickling step in the deep impurity removal treatment uses a hydrochloric acid solution with a concentration of 19%-20%, soaking at room temperature for 1.8-2 hours, and supplemented by ultrasonic vibration to thoroughly remove the oxide scale and rust on the surface of the raw material.

3. The process for preparing wear-resistant cold-drawn steel according to claim 1, characterized in that: In the multi-stage cold drawing deformation process, the cold drawing rate in the rough drawing stage is 28%-30%, the cold drawing rate in the intermediate drawing stage is 13%-14%, and the cold drawing rate in the fine drawing stage is 7%-8%. The cold drawing stress in each stage is precisely set according to the material of the steel and the required finished product size. The deformation speed is controlled at 8-12mm / s, and special lubricants are used to reduce friction and wear.

4. The process for preparing wear-resistant cold-drawn steel according to claim 1, characterized in that: The wear-resistant coating of the cemented carbide mold with a nano-scale tungsten carbide-titanium carbide-aluminum oxide-silicon nitride composite wear-resistant coating has a thickness of 10-15 nanometers, wherein the weight ratio of tungsten carbide, titanium carbide, aluminum oxide and silicon nitride is 4:2:1:1 to 5:2:1:1, and the amount of graphene added is 0.5%-1.5% of the total weight of the coating to improve the wear resistance, hardness and thermal shock resistance of the mold.

5. The process for preparing wear-resistant cold-drawn steel according to claim 1, characterized in that: The temperature of vacuum quenching treatment is 830-840 degrees Celsius, the holding time is 1.8-2.2 hours, and the quenching medium is specially purified high-pressure nitrogen with a pressure of 3-4MPa to ensure that the steel obtains a uniform and refined martensitic structure.

6. The process for preparing wear-resistant cold-drawn steel according to claim 1, characterized in that: The low-temperature tempering treatment adopts a variable temperature tempering process, first keeping it at 180-190 degrees Celsius for 2 hours, and then keeping it at 200-210 degrees Celsius for 1 hour to maintain the high hardness, good toughness and resistance to temper brittleness of the steel.

7. The process for preparing wear-resistant cold-drawn steel according to claim 1, characterized in that: Before the cold drawing deformation step, the raw materials are also preheated at a temperature of 630-640 degrees Celsius and a holding time of 1-1.25 hours to improve the plasticity of the steel and reduce the cold drawing deformation resistance, while promoting the dissolution and uniform distribution of micro-alloying elements.

8. The process for preparing wear-resistant cold-drawn steel according to claim 1, characterized in that: After the mold forming step, the cold-drawn steel is also subjected to ultra-smooth surface polishing, using diamond grinding paste with a particle size of W0.25-W0.5, supplemented by electrolytic polishing technology to improve its surface finish, reduce the friction coefficient and enhance wear resistance.

9. The process for preparing wear-resistant cold-drawn steel according to claim 1, characterized in that: It also includes surface residual stress elimination and strengthening treatment of cold-drawn steel before vacuum quenching treatment, through high-frequency induction heating and subsequent rapid cooling to reduce surface residual tensile stress, improve surface hardness and fatigue resistance.

10. The process for preparing wear-resistant cold-drawn steel according to claim 1, characterized in that: After low-temperature tempering treatment, the cold-drawn steel is also subjected to comprehensive performance testing and evaluation, including hardness testing, toughness testing, wear resistance testing, fatigue strength testing, and corrosion performance testing, to ensure that its comprehensive performance meets the design requirements, and qualified products are packaged, labeled, and traced.

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