High stress relaxation resistant 60si2mn spring steel and method of making same

Abstract

The present application relates to spring steel preparation technical field, specifically to a kind of high stress relaxation resistance 60Si2Mn spring steel and its preparation method, comprising the following steps: raw material preparation and intelligent screening, precision blanking, self-adapting straightening, gradient quenching treatment, intelligent temperature control tempering treatment, nano coating surface treatment, whole-process quality traceability and finished product inspection;Beneficial effect is: using intelligent screening system, integrates machine vision and spectral analysis technology, the chemical composition of raw material is quickly and accurately tested, to ensure that each batch of raw materials meets the preset standard, improves the stability and consistency of raw material quality.Reduces the error and uncertainty caused by manual operation, improves the inspection efficiency and accuracy, reduces the production risk caused by raw material problem.

Description

Technical Field

[0001] This invention relates to the field of spring steel preparation, specifically to a high stress relaxation 60Si2Mn spring steel and its preparation method. Background Technology

[0002] In manufacturing, particularly in the production of high-strength, high-durability components such as spring steel, the requirements for material properties are becoming increasingly stringent. 60Si2Mn spring steel, as a widely used spring material, plays a crucial role in the automotive, machinery, and aerospace industries due to its excellent elasticity, fatigue strength, and resistance to stress relaxation. However, with the increasing complexity of application environments and the rising performance requirements for components, traditional manufacturing processes are no longer sufficient to meet all demands, mainly in the following aspects: Traditional raw material inspection methods rely on manual operation, which is inefficient and prone to errors, making it difficult to ensure that the chemical composition of each batch of raw materials strictly meets standards, thus affecting the performance stability of the final product. Quenching and tempering, as key heat treatment steps in spring steel production, have a decisive impact on material properties due to the control of their temperature, time, and cooling rate. Traditional methods struggle to achieve precise control, easily leading to problems such as uneven hardness and stress concentration, reducing the spring's fatigue resistance and stress relaxation resistance. Spring steel often faces corrosive environments during use. Traditional surface treatment technologies such as electroplating and painting, while providing a certain degree of corrosion protection, suffer from uneven coating thickness, easy peeling, and poor environmental performance, limiting the long-term use of spring steel in harsh environments. Quality control at every stage of the production process is crucial. Traditional methods largely rely on manual recording and sampling inspection, making it difficult to achieve full-process quality traceability and real-time monitoring, increasing quality risks and management costs. Summary of the Invention

[0003] The purpose of this invention is to provide a high stress relaxation 60Si2Mn spring steel and its preparation method, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a high stress relaxation resistance 60Si2Mn spring steel, wherein the chemical composition of the spring steel, by mass percentage, includes: carbon (C) 0.58-0.65%, silicon (Si) 1.50-2.00%, manganese (Mn) 0.60-0.90%, and innovatively adds trace amounts of niobium (Nb) 0.02-0.05% and vanadium (V) 0.01-0.03% to refine the grains and improve the stress relaxation resistance of the steel; chromium (Cr) ≤0.35%, nickel (Ni) ≤0.35%, copper (Cu) ≤0.25%, phosphorus (P) ≤0.030%, sulfur (S) ≤0.030%, with the balance being iron (Fe) and unavoidable impurities; and the spring steel is obtained by heat treatment combined with gradient cooling technology.

[0005] Preferably, the heat treatment process includes gradient quenching and intelligent temperature-controlled tempering. Gradient quenching involves first rapidly cooling to a medium temperature range of 600-650℃, and then slowly cooling to room temperature to reduce quenching stress and optimize the microstructure. Intelligent temperature-controlled tempering involves real-time monitoring and adjustment of the tempering temperature to 450-500℃.

[0006] A method for preparing high stress relaxation 60Si2Mn spring steel includes the following steps: Raw material preparation and intelligent screening: Machine vision and spectral analysis technology are used to quickly and accurately inspect the steel grade, specifications, furnace number, manufacturer and chemical composition of raw materials to ensure that the raw materials meet the preset chemical composition requirements; qualified raw materials are labeled and classified for storage for subsequent processing. Precision cutting: According to product design requirements, a high-precision laser cutting machine is used to cut raw materials to ensure accurate cutting dimensions; during the cutting process, batch cutting is carried out after the first inspection is qualified, and anti-loosening devices are set up at the workstations to prevent out-of-tolerance or scrap. Adaptive straightening: The cut steel plate is placed on an adaptive straightening machine. Through pressure sensors and a feedback control system, the straightening pressure is automatically adjusted according to the deformation of the steel plate. During the straightening process, it is ensured that the straightening indentation of the plate is a smooth, rounded arc, and horizontal strip-shaped indentations are not allowed. The indentation depth is less than 0.3mm. The straightened steel plate must be inspected by high-precision visual inspection and machine vision. Steel plates with cracks must be removed in time. Gradient quenching treatment: The straightened steel plates are placed into the furnace, ensuring uniform distribution and maintaining a specific gap between the plates; multi-stage cooling rate control is adopted, first rapidly heating to the quenching temperature of 850-880℃, holding at this temperature to fully austenitize the steel plate; then rapidly cooling to the medium temperature range of 600-650℃; finally, slowly cooling to room temperature to form a fine martensitic structure, improving the strength and toughness of the steel; after quenching, the steel plate needs to undergo high-precision patch inspection and ultrasonic flaw detection technology to ensure that there are no internal defects and the hardness meets the process requirements; Intelligent temperature-controlled tempering: The quenched steel plate is placed in an intelligent temperature-controlled tempering furnace. Through an integrated temperature sensor and intelligent control system, the tempering temperature is monitored and adjusted in real time to 450-500℃. The tempering time is precisely controlled according to the steel plate thickness and required hardness to ensure that the hardness of the steel plate after tempering is precisely controlled within the range of 55-62HRC. Circulating air cooling technology is used during the tempering process to ensure uniform cooling of the steel plate. After tempering, the steel plate undergoes hardness re-inspection and surface quality inspection to ensure that it meets the process requirements. Nano-coating surface treatment: After tempering, the steel plate is shot-blasted to Sa2.5 grade to remove surface oil, rust, and dirt; electrostatic spraying technology is used to spray a uniform primer layer on the steel plate surface with a thickness of 20-30μm; during the spraying process, the application viscosity, leveling time, and curing time must be controlled to ensure the quality of the paint film; using chemical vapor deposition (CVD) or physical vapor deposition (PVD) technology, a dense nano-coating layer is deposited on the primer surface with a thickness controlled between 10-20nm; high-precision laser marking technology is used to print clear and standardized lettering and markings on the nano-coating surface, ensuring that the lettering is not skewed and is neatly and consistently arranged; Full-process quality traceability and finished product inspection: By integrating RFID tags and QR code technology, each steel plate is uniquely identified, realizing full-process quality traceability from raw materials to finished products; finished product inspection includes high-precision hardness inspection, arc height inspection, surface quality inspection and paint film thickness inspection; qualified products must be properly labeled and stacked on intelligent material racks according to regulations.

[0007] Preferably, during the gradient quenching process, the steel plates are placed into the furnace in a uniform distribution, and a specific gap is maintained between the steel plates, with multi-stage cooling rate control adopted.

[0008] Preferably, during the intelligent temperature-controlled tempering process, the temperature inside the tempering furnace is monitored and adjusted in real time by integrating a temperature sensor and an intelligent control system to ensure that the hardness of the steel plate after tempering is precisely controlled within the range of 55-62 HRC.

[0009] Preferably, in the nano-coating surface treatment step, the painting adopts electrostatic spraying technology combined with nano-coating deposition technology. First, a basic paint film is formed by electrostatic spraying, and then the nano-coating is deposited using CVD or PVD technology.

[0010] Preferably, in the process of full-process quality traceability and finished product inspection, RFID tags and QR code technology are used to achieve full-process quality traceability, ensuring that product quality is controllable and traceable.

[0011] Preferably, the surface quality of the spring steel is required to be free from damage, cracks, and overheating / burning marks, and its corrosion resistance and service life are improved through nano-coating technology.

[0012] Preferably, in the raw material preparation and intelligent screening steps, machine vision and spectral analysis technologies are used to ensure the quality of raw materials, providing a reliable guarantee for subsequent processing.

[0013] Preferably, in the precision blanking and adaptive straightening steps, high-precision laser cutting and adaptive straightening technology are used to ensure the accuracy of the steel plate dimensions and the quality of the straightening, providing a foundation for subsequent heat treatment.

[0014] Compared with the prior art, the beneficial effects of the present invention are: The present invention proposes a high-stress-relaxation-resistant 60Si2Mn spring steel and its preparation method. It employs an intelligent screening system integrating machine vision and spectral analysis technology to rapidly and accurately inspect the chemical composition of raw materials, ensuring that each batch of raw materials meets preset standards and improving the stability and consistency of raw material quality. This reduces errors and uncertainties caused by manual operation, improves inspection efficiency and accuracy, and lowers production risks due to raw material issues.

[0015] Gradient quenching effectively reduces quenching stress, optimizes the microstructure of steel, and improves its resistance to stress relaxation and fatigue strength by controlling the cooling rate. Intelligent temperature-controlled tempering precisely controls the tempering temperature and time, adjusting the hardness and toughness of the steel to meet different application requirements, while avoiding defects such as overheating, burning, or cracking. Nano-coating surface treatment technology forms a dense and uniform nano-coating, significantly improving the corrosion resistance of spring steel and enabling it to be used for extended periods in harsh environments without easily corroding. The nano-coating adheres tightly to the substrate, is not easily peeled off, and possesses excellent wear resistance and self-lubricating properties, further extending the service life of the spring steel. Compared to traditional methods such as electroplating and painting, nano-coating surface treatment technology reduces the use and emission of harmful substances, making it more environmentally friendly and sustainable. It improves the service life and performance stability of spring steel, reduces replacement frequency and resource waste, aligning with the development trends of green manufacturing and a circular economy.

[0016] By employing comprehensive quality traceability and inspection methods, including high-precision patch testing, ultrasonic flaw detection, hardness testing, arc height testing, and paint film thickness testing, we ensure that the quality at every stage meets the required standards. This reduces the tedious process of manual recording and sampling inspection, improves management efficiency and the accuracy of quality control, and lowers quality risks and management costs. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clear and complete, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some, not all, embodiments of the present invention, and are merely illustrative of the embodiments of the present invention. They are not intended to limit 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.

[0019] Example 1: The present invention provides a technical solution: implementation of raw material preparation and intelligent screening of high stress relaxation 60Si2Mn spring steel.

[0020] In the preparation of high-stress-relaxation-resistant 60Si2Mn spring steel, the quality of raw materials directly affects the performance of the final product. Therefore, the preparation and intelligent screening of raw materials are the first step in ensuring product quality.

[0021] Implementation steps: Raw material receiving and preliminary inspection: Receive 60Si2Mn spring steel raw materials from the supplier, check if the packaging is intact and the markings are clear. Conduct a preliminary inspection of the raw materials' appearance to ensure there is no obvious damage, cracks, or rust.

[0022] Intelligent screening system startup: Place the raw materials on the conveyor belt of the intelligent screening system, and the system will start automatically. The intelligent screening system integrates machine vision and spectral analysis technology to quickly and accurately inspect the steel grade, specifications, furnace number, manufacturer, and chemical composition of the raw materials.

[0023] Chemical composition analysis: A spectrometer is used to perform non-destructive chemical composition analysis on the raw materials to ensure that the contents of key elements such as carbon (C), silicon (Si), manganese (Mn), niobium (Nb), and vanadium (V) meet the preset requirements (C: 0.58-0.65%, Si: 1.50-2.00%, Mn: 0.60-0.90%, Nb: 0.02-0.05%, V: 0.01-0.03%). Simultaneously, the contents of impurities such as chromium (Cr), nickel (Ni), copper (Cu), phosphorus (P), and sulfur (S) are detected to ensure that they do not exceed the allowable range (Cr ≤0.35%, Ni ≤0.35%, Cu≤0.25%, P ≤0.030%, S ≤0.030%).

[0024] Intelligent screening and classification: Based on the chemical composition analysis results, the intelligent screening system automatically determines whether the raw materials are qualified. Qualified raw materials are transported to a designated area for labeling and classification storage for subsequent processing. Unqualified raw materials are marked and isolated to prevent them from being mixed with qualified materials.

[0025] The intelligent screening system enables rapid and accurate inspection of raw material quality, ensuring that the raw materials used in subsequent processing all meet the chemical composition requirements, thus laying the foundation for the preparation of high-quality, high-stress-relaxation-resistant 60Si2Mn spring steel.

[0026] Example 2: Gradient quenching treatment of high stress relaxation 60Si2Mn spring steel.

[0027] Gradient quenching is a key step in the preparation of high stress relaxation 60Si2Mn spring steel. By controlling the cooling rate, the microstructure of the steel can be optimized and its stress relaxation resistance can be improved.

[0028] Implementation steps: Preparation before quenching: Place the straightened 60Si2Mn spring steel plates into the furnace, ensuring even distribution and maintaining specific gaps between the plates to allow for uniform flow of the cooling medium. Check that the quenching furnace equipment is functioning properly and that the cooling system is unobstructed.

[0029] Heating and holding: Start the quenching furnace and heat the steel plate to the quenching temperature (850-880℃), hold for a certain time (e.g., 30 minutes) to fully austenitize the steel plate.

[0030] Gradient cooling: Multi-stage cooling rate control is adopted. First, the temperature is rapidly cooled to the medium temperature range of 600-650℃ and held for 10 minutes to reduce quenching stress. Then, it is slowly cooled to room temperature, with the cooling rate controlled at no more than 10℃ per minute to form a fine martensitic structure. After quenching, the steel plate must undergo high-precision patch inspection and ultrasonic flaw detection technology to ensure that there are no internal defects such as cracks and porosity.

[0031] Check whether the hardness of the steel plate meets the process requirements.

[0032] Gradient quenching effectively reduced quenching stress, optimized the microstructure of the steel, and improved its resistance to stress relaxation. The hardness and internal quality of the quenched steel plate met the process requirements, providing a good foundation for subsequent tempering.

[0033] Example 3: Implementation of intelligent temperature-controlled tempering treatment for high stress relaxation 60Si2Mn spring steel.

[0034] Intelligent temperature-controlled tempering is another key step in the preparation of high stress relaxation 60Si2Mn spring steel. By precisely controlling the tempering temperature and time, the hardness and toughness of the steel can be adjusted to meet different application requirements.

[0035] Implementation steps: Preparation before tempering: Place the quenched 60Si2Mn spring steel plate into the intelligent temperature-controlled tempering furnace, ensuring the steel plate is evenly distributed. Check whether the tempering furnace equipment is functioning properly and whether the temperature sensor and intelligent control system are accurate and reliable.

[0036] Intelligent temperature control tempering: When the tempering furnace is started, the tempering temperature is monitored and adjusted in real time to 450-500℃ through an integrated temperature sensor and intelligent control system.

[0037] Based on the steel plate thickness and required hardness, the tempering time is precisely controlled for 2 hours to ensure that the hardness of the steel plate after tempering is precisely controlled within the range of 55-62 HRC. Circulating air cooling technology is used during the tempering process to ensure uniform cooling of the steel plate and avoid uneven hardness.

[0038] Post-tempering inspection: The tempered steel plate needs to undergo a hardness retest to ensure that the hardness meets the process requirements. Inspect the surface quality of the steel plate to ensure there are no defects such as overheating, burning, or cracks.

[0039] Through intelligent temperature-controlled tempering, the tempering temperature and time were precisely controlled, adjusting the hardness and toughness of the steel to meet different application requirements. After tempering, the hardness and surface quality of the steel plate met the process requirements, providing a good foundation for subsequent surface treatments.

[0040] Example 4: Implementation of nano-coating surface treatment for high stress relaxation 60Si2Mn spring steel.

[0041] Nano-coating surface treatment is the final step in the preparation process of high stress relaxation 60Si2Mn spring steel. By forming a dense nano-coating, the corrosion resistance and service life of the steel can be significantly improved.

[0042] Implementation steps: Surface pretreatment: The tempered 60Si2Mn spring steel plate is shot-blasted to Sa2.5 grade to remove surface oil, rust, and dirt. The steel plate surface is checked for flatness and defects to provide a good foundation for subsequent coating treatment.

[0043] Electrostatic spraying: Using electrostatic spraying technology, a uniform primer layer with a thickness of 20-30μm is sprayed onto the steel plate surface. The application viscosity, leveling time, and curing time are controlled to ensure a uniform paint film quality free of defects such as sagging and pinholes.

[0044] Nanocoating deposition: A dense nanocoating layer is deposited on the primer surface using chemical vapor deposition (CVD) or physical vapor deposition (PVD) techniques, with a thickness controlled between 10-20 nm. The nanocoating material is selected from compounds with excellent corrosion resistance, such as titanium nitride (TiN) or silicon carbide (SiC).

[0045] Printing and Finished Product Inspection: High-precision laser marking technology is used to print clear and standardized lettering and markings on the nano-coating surface, ensuring that the lettering is straight and neatly arranged. The entire process of finished product quality traceability and inspection is conducted, including hardness testing, arc height testing, surface quality inspection, and paint film thickness testing, to ensure that all product performance indicators meet process requirements.

[0046] Nano-coating surface treatment significantly improves the corrosion resistance and service life of 60Si2Mn spring steel. The coating surface is smooth, uniform, and defect-free, with clear and standardized printing, meeting the high performance requirements of spring steel in high-end applications.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-stress-relaxation-resistant 60Si2Mn spring steel, characterized in that: The chemical composition of the spring steel, by mass percentage, includes: carbon (C) 0.58-0.65%, silicon (Si) 1.50-2.00%, manganese (Mn) 0.60-0.90%, and innovatively adds trace amounts of niobium (Nb) 0.02-0.05% and vanadium (V) 0.01-0.03% to refine the grains and improve the steel's resistance to stress relaxation; chromium (Cr) ≤0.35%, nickel (Ni) ≤0.35%, copper (Cu) ≤0.25%, phosphorus (P) ≤0.030%, sulfur (S) ≤0.030%, with the balance being iron (Fe) and unavoidable impurities; and the spring steel is produced by heat treatment combined with gradient cooling technology.

2. The high stress relaxation resistant 60Si2Mn spring steel according to claim 1, characterized in that: The heat treatment process includes gradient quenching and intelligent temperature-controlled tempering. Gradient quenching involves first rapidly cooling to a medium temperature range of 600-650℃, and then slowly cooling to room temperature to reduce quenching stress and optimize the microstructure. Intelligent temperature-controlled tempering involves real-time monitoring and adjustment of the tempering temperature to 450-500℃.

3. A method for preparing high stress relaxation 60Si2Mn spring steel, used to prepare the high stress relaxation 60Si2Mn spring steel according to any one of claims 1-2, characterized in that: The preparation method includes the following steps: Raw material preparation and intelligent screening: Machine vision and spectral analysis technology are used to quickly and accurately inspect the steel grade, specifications, furnace number, manufacturer and chemical composition of raw materials to ensure that the raw materials meet the preset chemical composition requirements; qualified raw materials are labeled and classified for storage for subsequent processing. Precision cutting: According to product design requirements, a high-precision laser cutting machine is used to cut raw materials to ensure accurate cutting dimensions; during the cutting process, batch cutting is carried out after the first inspection is qualified, and anti-loosening devices are set up at the workstations to prevent out-of-tolerance or scrap. Adaptive straightening: The cut steel plate is placed on an adaptive straightening machine. Through pressure sensors and a feedback control system, the straightening pressure is automatically adjusted according to the deformation of the steel plate. During the straightening process, it is ensured that the straightening indentation of the plate is a smooth, rounded arc, and horizontal strip-shaped indentations are not allowed. The indentation depth is less than 0.3mm. The straightened steel plate must be inspected by high-precision visual inspection and machine vision. Steel plates with cracks must be removed in time. Gradient quenching treatment: The straightened steel plates are placed into the furnace, ensuring uniform distribution and maintaining a specific gap between the plates; multi-stage cooling rate control is adopted, first rapidly heating to the quenching temperature of 850-880℃, holding at this temperature to fully austenitize the steel plate; then rapidly cooling to the medium temperature range of 600-650℃; finally, slowly cooling to room temperature to form a fine martensitic structure, improving the strength and toughness of the steel; after quenching, the steel plate needs to undergo high-precision patch inspection and ultrasonic flaw detection technology to ensure that there are no internal defects and the hardness meets the process requirements; Intelligent temperature-controlled tempering: The quenched steel plate is placed in an intelligent temperature-controlled tempering furnace. Through an integrated temperature sensor and intelligent control system, the tempering temperature is monitored and adjusted in real time to 450-500℃. The tempering time is precisely controlled according to the steel plate thickness and required hardness to ensure that the hardness of the steel plate after tempering is precisely controlled within the range of 55-62HRC. Circulating air cooling technology is used during the tempering process to ensure uniform cooling of the steel plate. After tempering, the steel plate undergoes hardness re-inspection and surface quality inspection to ensure that it meets the process requirements. Nano-coating surface treatment: After tempering, the steel plate is shot-blasted to Sa2.5 grade to remove surface oil, rust, and dirt; electrostatic spraying technology is used to spray a uniform primer layer on the steel plate surface with a thickness of 20-30μm; during the spraying process, the application viscosity, leveling time, and curing time must be controlled to ensure the quality of the paint film; using chemical vapor deposition (CVD) or physical vapor deposition (PVD) technology, a dense nano-coating layer is deposited on the primer surface with a thickness controlled between 10-20nm; high-precision laser marking technology is used to print clear and standardized lettering and markings on the nano-coating surface, ensuring that the lettering is not skewed and is neatly and consistently arranged; Full-process quality traceability and finished product inspection: By integrating RFID tags and QR code technology, each steel plate is uniquely identified, realizing full-process quality traceability from raw materials to finished products; finished product inspection includes high-precision hardness inspection, arc height inspection, surface quality inspection and paint film thickness inspection; qualified products must be properly labeled and stacked on intelligent material racks according to regulations.

4. The method for preparing a high stress relaxation 60Si2Mn spring steel according to claim 3, characterized in that: During the gradient quenching process, the steel plates are placed into the furnace to ensure uniform distribution and maintain a specific gap between them, and multi-stage cooling rate control is adopted.

5. The method for preparing a high stress relaxation 60Si2Mn spring steel according to claim 3, characterized in that: During the intelligent temperature-controlled tempering process, the temperature inside the tempering furnace is monitored and adjusted in real time by integrating temperature sensors and an intelligent control system to ensure that the hardness of the steel plate after tempering is precisely controlled within the range of 55-62 HRC.

6. The method for preparing a high stress relaxation 60Si2Mn spring steel according to claim 3, characterized in that: In the nano-coating surface treatment step, the painting adopts electrostatic spraying technology, combined with nano-coating deposition technology. First, a basic paint film is formed by electrostatic spraying, and then the nano-coating is deposited using CVD or PVD technology.

7. The method for preparing a high stress relaxation 60Si2Mn spring steel according to claim 1, characterized in that: In the process of full-process quality traceability and finished product inspection, RFID tags and QR code technology are used to achieve full-process quality traceability, ensuring that product quality is controllable and traceable.

8. The method for preparing a high stress relaxation 60Si2Mn spring steel according to claim 3, characterized in that: The surface quality of the spring steel is required to be free from damage, cracks, and overheating marks, and its corrosion resistance and service life are improved through nano-coating technology.

9. The method for preparing a high stress relaxation 60Si2Mn spring steel according to claim 3, characterized in that: In the raw material preparation and intelligent screening steps, machine vision and spectral analysis technologies are used to ensure the quality of raw materials, providing a reliable guarantee for subsequent processing.

10. The method for preparing a high stress relaxation 60Si2Mn spring steel according to claim 1, characterized in that: In the precision blanking and adaptive straightening steps, high-precision laser cutting and adaptive straightening technology are used to ensure the accuracy of steel plate dimensions and the quality of straightening, providing a foundation for subsequent heat treatment.

Images