Carbon steel wire production process

Abstract

The invention discloses a production process of a carbon steel wire, which improves the comprehensive performance of the steel wire through chemical component optimization, drawing process improvement and heat treatment technology innovation. The process comprises the following steps that a high-carbon wire rod serves as a raw material, and the high-carbon wire rod comprises the following chemical components of 0.71%-0.88% of C, 0.6%-1% of Mn, 0.3%-0.5% of Cr, 0.2%-0.4% of Si, 0.15%-0.25% of Mo, 0.05%-0.15% of V, 0.05%-0.15% of rare earth elements, smaller than or equal to 0.025% of P and smaller than or equal to 0.025% of S; oxide skin is removed through acid pickling, and a lubricant is coated after neutralization; 11-pass step-by-step drawing is adopted, the drawing rate is 19%-30%, and the drawing speed is gradually increased to 1.8 m / s from 0.3 m / s; intermediate annealing is carried out after the third pass and the sixth pass; laser surface hardening is adopted after drawing is completed; and finally quenching and tempering. The process obviously improves the strength, toughness and wear resistance of the steel wire, optimizes the surface quality and dimensional precision, improves the production efficiency, reduces the environmental influence, and is suitable for the occasions of bridge cables, high-strength springs and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of steel wires, and in particular relates to a production process of carbon steel wires. Background Art

[0002] Carbon steel wire is widely used in bridge cables, building structures, high-strength springs, industrial screens, etc. due to its excellent strength, toughness and wear resistance. The traditional carbon steel wire production process includes hot rolling, pickling, drawing, heat treatment and other steps. However, with the continuous improvement of industrial demand, the traditional process has exposed many problems in performance and efficiency.

[0003] Carbon steel wire needs to work for a long time under high load and high fatigue environment, so it is required to have high strength, good toughness and excellent fatigue performance. However, the traditional production of carbon steel wire mainly relies on increasing carbon content and increasing deformation processing to improve strength, which often leads to reduced toughness of the material and even brittle fracture. At the same time, the wear resistance and corrosion resistance of steel wire are also difficult to meet the demanding requirements of modern industry, especially in long-term stress-bearing components such as bridge cables and high-strength springs. The strength and toughness of traditional carbon steel wire are often difficult to balance. In practical applications, high-strength steel wire is prone to failure due to brittle fracture, while the strength of high-toughness steel wire is not enough to meet the needs of heavy-load occasions. In addition, the wear resistance and fatigue performance of steel wire are also difficult to meet the harsh conditions of high-frequency vibration and heavy-load stretching. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a carbon steel wire production process.

[0005] The technical solution provided by the present invention is as follows:

[0006] A carbon steel wire production process comprises the following steps:

[0007] S1: Select high carbon wire rod as raw material, with a diameter of 6.5mm, and its chemical element composition is: C: 0.71-0.88%, Mn: 0.6-1%, Cr: 0.30-0.50%, Si: 0.2-0.4%, Mo: 0.15-0.25%, V: 0.05-0.15%, rare earth elements: 0.05-0.15%, P≤0.025%, S≤0.025%;

[0008] S2: The impurities such as scale and rust on the surface of the wire rod are removed by pickling process. After pickling, the surface of the steel rod is neutralized with a neutralizing solution to ensure the removal of acidic substances;

[0009] S3: Lubricant is applied on the surface of the wire rod, the lubricant includes graphite powder, calcium-based lubricant or composite lubricant, the applied lubricant is evenly covered on the surface of the wire rod, and continuous lubrication is ensured during the drawing process;

[0010] S4: adopting a step-by-step drawing process, the initial drawing rate is 0.3m / s to 0.5m / s, gradually increasing to 0.5m / s to 1.8m / s, the drawing rate is 19% to 30%, and the wire diameter is gradually reduced through 11 drawing processes;

[0011] S5: Intermediate annealing, which is performed after the 3rd and 6th drawing passes;

[0012] S6: Surface hardening treatment: after drawing, the surface of the steel wire is hardened by laser hardening process;

[0013] S7: The steel wire surface is pickled after hardening to remove oxides and impurities formed during the hardening process. After pickling, an alkaline washing process is used to neutralize the acid residue to ensure a clean steel wire surface;

[0014] S8: The steel wire after drawing and hardening is subjected to final heat treatment, using a quenching and tempering process, with a quenching temperature of 850°C to 900°C, a holding time of 20 to 30 minutes, a tempering temperature of 200°C to 300°C, a holding time of 1 to 2 hours, and then cooled to room temperature.

[0015] In some embodiments, the chemical element composition of the high carbon wire rod is: C: 0.88%, Mn: 0.65%, Cr: 0.3%, Si: 0.25%, Mo: 0.15%, V: 0.1%, rare earth elements: 0.08%, P≤0.025%, S≤0.025%.

[0016] In some embodiments, the rare earth element is Ce or Y.

[0017] In some embodiments, the surface lubricant includes graphite powder, calcium-based lubricant or composite lubricant, and the coating amount is 0.1 g to 0.3 g per square meter of the steel wire surface.

[0018] In some embodiments, the intermediate annealing temperature is 650° C. and the holding time is 1.5 hours.

[0019] In some embodiments, the laser power is 300W to 500W, the scanning speed is 5m / min to 10m / min, the laser hardening temperature is controlled at 800°C to 1000°C, the hardening depth is controlled at 0.5mm to 1.0mm, and the laser hardening is cooled to room temperature after cooling.

[0020] In some embodiments, the tempering temperature in the final heat treatment process is 250° C., and the tempering time is 1.5 hours.

[0021] In summary, the beneficial effects of the present invention are:

[0022] (1) The present invention not only greatly improves the comprehensive performance of carbon steel wire through chemical composition optimization, drawing process innovation and heat treatment improvement, but also achieves significant improvements in production efficiency, economy and environmental friendliness, and has broad application prospects.

[0023] (2) The present invention optimizes the chemical composition, introduces vanadium, molybdenum and rare earth elements, strengthens the grain boundary and matrix structure of the steel wire, significantly improves the hardenability of the steel, enables the steel to achieve higher hardness and more uniform performance distribution after heat treatment, and improves the strength and toughness of the material. Especially in a high stress environment, it can significantly extend the fatigue life of the steel wire.

[0024] (3) The present invention reduces the friction damage on the surface of the steel wire and improves the surface finish by combining a reasonable drawing speed with uniform coating of a surface lubricant, thereby providing a high-quality foundation for subsequent coating or plating treatment. At the same time, an intermediate annealing process is added during the drawing process to eliminate the brittle accumulation caused by work hardening, thereby providing better ductility for subsequent processing.

[0025] (4) After drawing, the present invention uses a laser hardening process to harden the surface of the steel wire, which significantly improves the surface wear resistance and fatigue resistance of the steel wire, making it more stable under high-frequency vibration and heavy-load tensile environments. DETAILED DESCRIPTION

[0026] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The following examples are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0027] The present invention provides a carbon steel wire production process, comprising the following steps:

[0028] S1: Select high carbon wire rod as raw material, with a diameter of 6.5mm, and its chemical element composition is: C: 0.71-0.88%, Mn: 0.6-1%, Cr: 0.30-0.50%, Si: 0.2-0.4%, Mo: 0.15-0.25%, V: 0.05-0.15%, rare earth elements: 0.05-0.15%, P≤0.025%, S≤0.025%.

[0029] Wherein, the rare earth element is Ce or Y.

[0030] Specifically, C is carbon, which is a key element that determines the strength and hardness of the steel wire. A higher carbon content can increase the tensile strength and hardness of the steel wire, but will reduce its plasticity and toughness. The carbon content within the range provided in this application can provide a better balance between strength and processing performance.

[0031] Mn is manganese, which helps to improve the strength and toughness of the steel wire, and can also improve the oxidation resistance and wear resistance of the steel wire. It can also improve the heat treatment response of the steel wire and enhance its heat resistance.

[0032] Cr is chromium, which can improve the wear resistance, corrosion resistance and hardness of steel wire. Appropriate amount of chromium helps to improve the fatigue performance of steel wire, especially when used under high load.

[0033] Si is silicon, which helps to improve the steel wire's anti-oxidation ability and enhance its high temperature resistance. Silicon can also promote the removal of impurities from the steel wire and improve the cleanliness of the steel.

[0034] Mo is molybdenum, which helps to improve the high temperature resistance of the steel wire and enhance its corrosion resistance. It can also improve the wear resistance and hardness of the steel wire, especially in an environment with high working temperature.

[0035] V is vanadium. In this application, vanadium can effectively refine the grains of the steel wire and improve its comprehensive mechanical properties. At the same time, vanadium has a significant effect on improving the fatigue resistance of the steel wire, especially in applications that bear alternating loads.

[0036] Ce is cerium, Y is yttrium, and rare earth elements are used in the steel refining process in this application to effectively remove harmful impurities in the steel and improve the surface quality of the steel wire. At the same time, rare earth elements help to improve the fatigue resistance, oxidation resistance and comprehensive mechanical properties of the steel wire.

[0037] P stands for phosphorus, which is a harmful element. Excessive phosphorus will cause cold brittleness of steel wire, and the phosphorus content needs to be controlled through refining technology.

[0038] S is sulfur, which is a harmful element that usually reduces the ductility and toughness of steel wire. The sulfur content needs to be controlled during the production process and kept at a low level to avoid brittleness.

[0039] The chemical element composition of the steel wire in this application uses both vanadium and rare earth elements. In actual preparation, vanadium should be added first during the smelting process to fully combine it with the iron matrix, and then rare earth elements should be added at a lower temperature (about 1400°C) to avoid excessive volatilization of rare earth elements. Then, vacuum treatment is performed after adding rare earth elements to reduce the interference of oxygen and nitrogen and improve the utilization rate of rare earth elements.

[0040] After intermediate annealing and final heat treatment, the micronized carbides or nitrides formed by vanadium and rare earth elements are evenly distributed, thereby optimizing the strength and toughness of the steel.

[0041] The presence of vanadium increases the yield strength of steel and enhances its ability to resist plastic deformation; rare earth elements reduce surface defects of steel through inclusion control and reduce the origin of fatigue cracks, thereby significantly improving fatigue resistance. The combined effect of vanadium and rare earth elements significantly improves the hardenability of steel, allowing the steel to achieve higher hardness and more uniform performance distribution after heat treatment. Under high stress conditions, fatigue life can be extended by 20%-30%, and in salt spray tests, the corrosion resistance of steel wire is improved by about 40%.

[0042] S2: The pickling process is used to remove impurities such as oxide scale and rust on the surface of the wire rod. After pickling, the surface of the steel bar is neutralized with a neutralizing solution to ensure that the acidic substances are removed to avoid affecting the subsequent processes.

[0043] Specifically, the surface of the raw wire rod is usually covered with oxide scale and rust, and these impurities will affect the quality and efficiency of the subsequent drawing process. Therefore, the pickling process is required to remove the oxide scale and impurities. The process flow is as follows:

[0044] Pickling: Soak the wire rod in dilute sulfuric acid (5%-10%) or hydrochloric acid (10%-20%) solution for 5-10 minutes. During the pickling process, the oxide scale will react with the acid to form soluble salts, which can be washed off with water.

[0045] Neutralization treatment: To prevent acid residue from corroding the steel, an alkaline solution (such as sodium hydroxide or sodium carbonate solution) is used for neutralization treatment to ensure that the acid is completely removed.

[0046] Drying: After neutralization, the wire rod is dried to avoid residual moisture affecting the lubricant coating.

[0047] S3: Lubricant is applied on the surface of the wire rod, including graphite powder, calcium-based lubricant or composite lubricant, to reduce friction during drawing, improve drawing efficiency and wire surface quality. The applied lubricant is evenly covered on the surface of the wire rod and ensures continuous lubrication during the drawing process.

[0048] In the present application, the surface lubricant includes graphite powder, calcium-based lubricant or composite lubricant, and the coating amount is 0.1g to 0.3g per square meter of the steel wire surface.

[0049] S4: The wire drawing process is adopted, with the initial drawing rate of 0.3m / s to 0.5m / s, gradually increased to 0.5m / s to 1.8m / s, and the drawing rate is 19% to 30%. The wire diameter is gradually reduced through 11 drawing processes. The wire is lubricated after each drawing to avoid excessive friction between the die and the wire surface.

[0050] The drawing rate of 19%-30% provides an appropriate degree of plastic deformation, which increases the dislocation density of the steel wire and produces a significant strain hardening effect on the material, thereby improving the tensile strength and surface hardness of the steel wire. A drawing rate exceeding 30% may cause excessive work hardening, making the steel wire too brittle and hard, affecting subsequent ductility and fatigue properties; while a drawing rate below 19% will result in low processing efficiency and insignificant strengthening effect.

[0051] In the initial stage, a lower drawing speed (0.3m / s to 0.5m / s) is used, and gradually increased to a higher speed (0.5m / s to 1.8m / s) in the middle and late stages, which not only ensures the stability of the steel wire performance, but also significantly improves production efficiency. High-speed drawing reduces the processing time of a single pass, especially in the later stage of drawing, because the strength of the steel wire increases and the deformation resistance increases, high-speed drawing can greatly shorten the processing cycle.

[0052] S5: Intermediate annealing is carried out after the 3rd and 6th drawing. After annealing, a slow cooling process is used to release the internal stress of the steel wire, improve the ductility and plasticity of the steel wire, and facilitate subsequent drawing.

[0053] In the present application, the intermediate annealing temperature is 650° C. and the holding time is 1.5 hours.

[0054] S6: Surface hardening treatment. After drawing is completed, the surface of the steel wire is hardened using a laser hardening process.

[0055] In this application, the laser power is 300W to 500W, the scanning speed is 5m / min to 10m / min, the laser hardening temperature is controlled at 800℃ to 1000℃, the hardening depth is controlled at 0.5mm to 1.0mm, and the laser hardening is cooled to room temperature after cooling.

[0056] S7: The steel wire surface is pickled after hardening to remove oxides and impurities formed during the hardening process. After pickling, an alkaline washing process is used to neutralize the acid residue to ensure a clean steel wire surface;

[0057] S8: The steel wire after drawing and hardening is subjected to final heat treatment, using quenching and tempering process, with quenching temperature of 850℃ to 900℃, holding time of 20 to 30 minutes, tempering temperature of 200℃ to 300℃, holding time of 1 to 2 hours, and then cooled to room temperature. The mechanical properties of the steel wire are further improved after tempering.

[0058] In the present application, the tempering temperature in the final heat treatment process is 250° C., and the tempering time is 1.5 hours.

[0059] The steel wire prepared according to the present application has a tensile strength of 1200MPa to 1500MPa, a yield strength of 1000MPa to 1200MPa, and a surface hardness of HRC50 or above.

[0060] The present invention will be further illustrated by the following examples.

[0061] Example 1

[0062] S1: Select high carbon wire rod as raw material, with a diameter of 6.5 mm, and its chemical element composition is: C: 0.71%, Mn: 0.6%, Cr: 0.30%, Si: 0.2%, Mo: 0.15%, V: 0.05%, Ce: 0.05%, P≤0.025%, S≤0.025%;

[0063] S2: The impurities such as scale and rust on the surface of the wire rod are removed by pickling process. After pickling, the surface of the steel rod is neutralized with a neutralizing solution to ensure the removal of acidic substances;

[0064] S3: Lubricant is coated on the surface of the wire rod. The lubricant includes graphite powder, calcium-based lubricant or composite lubricant. The coated lubricant is evenly covered on the surface of the wire rod and ensures continuous lubrication during the drawing process. The surface lubricant is graphite powder or calcium-based lubricant, and the coating amount is 0.1g per square meter of the steel wire surface.

[0065] S4: adopting a step-by-step drawing process, the initial drawing rate is 0.3m / s to 0.5m / s, gradually increasing to 0.5m / s to 1.8m / s, the drawing rate is 19% to 30%, and the wire diameter is gradually reduced through 11 drawing processes;

[0066] The initial diameter of the high carbon wire rod in this embodiment is 6.5 mm, and the goal is to produce carbon steel wire with a diameter of 1.5 mm. Please refer to Table 1 for specific drawing data.

[0067] S5: Intermediate annealing, which is performed after the 3rd and 6th drawing passes. The intermediate annealing temperature is 650°C and the holding time is 1.5 hours.

[0068] Drawing pass Wire diameter(mm) Drawing rate (%) Pulling speed (m / s) Remark Initial state 6.5 - - Raw material high carbon wire rod First pull 5.8 20 0.3 Apply lubricant 2nd pull 5.2 19 0.4 Apply lubricant The third pull 4.6 21 0.5 Apply lubricant Intermediate annealing 4.6 - - Eliminate internal stress 4th pull 4.1 20 0.6 Apply lubricant 5th pull 3.7 19 0.7 Apply lubricant 6th pull 3.3 20 0.8 Apply lubricant Intermediate annealing 3.3 - - Eliminate internal stress Pull 7 2.9 23 0.9 Apply lubricant 8th pull 2.5 25 1.0 Apply lubricant 9th pull 2.1 25 1.2 Apply lubricant 10th pull 1.8 27 1.5 Apply lubricant 11th pull 1.5 30 1.8 Final product

[0069] Table 1

[0070] S6: Surface hardening treatment. After drawing, the surface of the steel wire is hardened by laser hardening process. The laser power is 300W, the scanning speed is 5m / min, the laser hardening temperature is controlled at 800℃, the hardening depth is controlled at 0.5mm, and it is cooled to room temperature after laser hardening.

[0071] S7: The steel wire surface is pickled after hardening to remove oxides and impurities formed during the hardening process. After pickling, an alkaline washing process is used to neutralize the acid residue to ensure a clean steel wire surface;

[0072] S8: The steel wire after drawing and hardening is subjected to final heat treatment, using a quenching and tempering process, with a quenching temperature of 850°C and a holding time of 20 minutes, a tempering temperature of 200°C and a holding time of 1 hour, and then cooled to room temperature.

[0073] Example 2

[0074] The difference from Example 1 lies in the chemical element composition of the high carbon wire rod, the selection of the coating lubricant, the parameters of the laser hardening process and the final heat treatment process. Specifically:

[0075] The chemical element composition of high carbon wire rod is: C: 0.8%, Mn: 1%, Cr: 0.50%, Si: 0.4%, Mo: 0.25%, V: 0.15%, Y: 0.15%, P≤0.025%, S≤0.025%.

[0076] The surface lubricant is a composite lubricant, and the coating amount is 0.3g per square meter of the steel wire surface.

[0077] Laser hardening process, laser power is 500W, scanning speed is 10m / min, laser hardening temperature is controlled at 1000℃, hardening depth is controlled at 1.0mm, and cooling to room temperature after laser hardening.

[0078] The final heat treatment was performed at a quenching temperature of 900°C for 30 minutes, a tempering temperature of 300°C for 2 hours, and then cooled to room temperature.

[0079] Example 3

[0080] The difference from Examples 1 and 2 lies in the chemical element composition of the high carbon wire rod, the selection of the coating lubricant, the parameters of the laser hardening process and the final heat treatment process. Specifically:

[0081] The chemical element composition of high carbon wire rod is: C: 0.88%, Mn: 0.65%, Cr: 0.3%, Si: 0.25%, Mo: 0.15%, V: 0.1%, Ce: 0.15%, P≤0.025%, S≤0.025%.

[0082] The surface lubricant is a composite lubricant, and the coating amount is 0.3g per square meter of the steel wire surface.

[0083] Laser hardening process, laser power is 400W, scanning speed is 8m / min, laser hardening temperature is controlled at 900℃, hardening depth is controlled at 0.7mm, and cooling to room temperature after laser hardening.

[0084] The final heat treatment was performed at a quenching temperature of 880°C for 25 minutes, a tempering temperature of 250°C for 1.5 hours, and then cooled to room temperature.

[0085] The carbon steel wires obtained by the processes of the above-mentioned embodiments 1-3 were all subjected to mechanical property tests. The specific test results are shown in Table 1:

[0086] Diameter / mm Tensile strength / MPa Yield Strength Surface hardness Example 1 1.5 1326 1049 52 Example 2 1.5 1402 1127 54 Example 3 1.5 1498 1188 58

[0087] Table 1

[0088] Compared with the carbon steel wire produced in the above embodiments, the carbon steel wire produced by a carbon steel wire production process of the invention has a tensile strength greater than 1200 to 1500 MPa, a yield strength of 1000 MPa to 1200 MPa, and a surface hardness of HRC50 or above, among which Embodiment 3 is the best embodiment of the present invention.

[0089] The above description shows and describes the preferred embodiments of the present invention. As mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A carbon steel wire production process, characterized in that: The following steps are involved: S1: Select high carbon wire rod as raw material, with a diameter of 6.5mm, and its chemical element composition is: C: 0.71-0.88%, Mn: 0.6-1%, Cr: 0.30-0.50%, Si: 0.2-0.4%, Mo: 0.15-0.25%, V: 0.05-0.15%, rare earth elements: 0.05-0.15%, P≤0.025%, S≤0.025%; S2: The impurities such as scale and rust on the surface of the wire rod are removed by pickling process. After pickling, the surface of the steel rod is neutralized with a neutralizing solution to ensure the removal of acidic substances; S3: Lubricant is applied on the surface of the wire rod, the lubricant includes graphite powder, calcium-based lubricant or composite lubricant, the applied lubricant is evenly covered on the surface of the wire rod, and continuous lubrication is ensured during the drawing process; S4: adopting a step-by-step drawing process, the initial drawing rate is 0.3m / s to 0.5m / s, gradually increasing to 0.5m / s to 1.8m / s, the drawing rate is 19% to 30%, and the wire diameter is gradually reduced through 11 drawing processes; S5: Intermediate annealing, which is performed after the 3rd and 6th drawing passes; S6: Surface hardening treatment: after drawing, the surface of the steel wire is hardened by laser hardening process; S7: The steel wire surface is pickled after hardening to remove oxides and impurities formed during the hardening process. After pickling, an alkaline washing process is used to neutralize the acid residue to ensure a clean steel wire surface; S8: The steel wire after drawing and hardening is subjected to final heat treatment, using a quenching and tempering process, with a quenching temperature of 850°C to 900°C, a holding time of 20 to 30 minutes, a tempering temperature of 200°C to 300°C, a holding time of 1 to 2 hours, and then cooled to room temperature.

2. The carbon steel wire production process according to claim 1, characterized in that: The chemical element composition of the high carbon wire rod is: C: 0.88%, Mn: 0.65%, Cr: 0.3%, Si: 0.25%, Mo: 0.15%, V: 0.1%, rare earth element: 0.08%, P≤0.025%, S≤0.025%.

3. The carbon steel wire production process according to claim 1, characterized in that: The rare earth element is Ce or Y.

4. The carbon steel wire production process according to claim 1, characterized in that: The surface lubricant includes graphite powder, calcium-based lubricant or composite lubricant, and the coating amount is 0.1g to 0.3g per square meter of the steel wire surface.

5. The carbon steel wire production process according to claim 1, characterized in that: The intermediate annealing temperature is 650° C., and the holding time is 1.5 hours.

6. The carbon steel wire production process according to claim 1, characterized in that: The laser power is 300W to 500W, the scanning speed is 5m / min to 10m / min, the laser hardening temperature is controlled at 800°C to 1000°C, the hardening depth is controlled at 0.5mm to 1.0mm, and the laser hardening is cooled to room temperature after cooling.

7. The carbon steel wire production process according to claim 1, characterized in that: The tempering temperature in the final heat treatment process is 250° C., and the tempering time is 1.5 hours.