An optimized process for reducing the coiling temperature of annealed cold heading steel

Abstract

This invention relates to the field of high-end steel material pressure processing technology, and discloses an optimized coiling temperature process for cold heading steel with reduced annealing. The process includes S1 pre-rolling preparation, S2 heating process, S3 rolling process control, S4 controlled cooling process optimization, S5 coiling and heat preservation process, and S6 quality inspection and feedback. This process achieves cost reduction and consumption reduction, alleviating environmental pressure. Through the core design of "reduced annealing," it eliminates 1-2 spheroidizing annealing steps in the traditional process, reducing annealing furnace energy consumption (based on a daily annealing capacity of 180 tons, saving 30-50% of electricity or natural gas consumption per month); it also reduces the number of pickling operations (reducing the frequency of cold acid pickling for specifications below Φ16mm and shot blasting for specifications above Φ16mm), reducing acidic wastewater discharge by 40-60%, and lowering environmental treatment costs by more than 30%; the production cycle is shortened from the traditional 3-5 days to 1-2 days, improving the capital turnover efficiency of downstream customers.

Description

Technical Field

[0001] This invention relates to the field of pressure processing technology for high-end steel materials, specifically to an optimized coiling temperature process for reducing the need for annealing in cold heading steel. Background Technology

[0002] Cold heading steel is widely used in the production of high-strength fasteners (such as bolts for automobiles, engines, and refrigeration equipment). Its processing places stringent requirements on the material's metallographic structure, tensile strength, and pull-out properties. In traditional cold heading steel production, the following key issues hinder the improvement of industry efficiency and product quality: Traditional processes are costly and environmentally burdensome. Traditional production uses a "two-balling, two-drawing" process (coil pickling → spheroidizing annealing → drawing → secondary spheroidizing annealing → precision drawing), which requires multiple annealing furnaces (electrically heated or naturally heated) for spheroidizing treatment, resulting in high energy consumption. At the same time, it relies on pickling to remove iron oxide scale, generating a large amount of acidic wastewater, which is costly to treat environmentally. Moreover, the overall production cycle takes several days, which cannot meet the high-efficiency production needs of downstream customers.

[0003] Poor mechanical properties and structural stability of materials: In traditional rolling processes, improper cooling control of cold heading steel wire rods (such as poor heat preservation effect of LCC air-cooled roller conveyor and cooling rate of 4-5℃ / s) easily leads to the formation of hard and brittle structures mainly composed of bainite and martensite (martensite has high hardness and poor plasticity). This results in wire rod tensile strength generally reaching 900-1040MPa, far exceeding the customer's expectation of ≤850MPa. Moreover, the tensile strength of the same ring fluctuates greatly (some batches fluctuate by more than 200MPa). The surface area reduction rate of the first drawing is only 10-18%, and the grain breakage is insufficient. It is difficult to achieve the 5.0-5.5 grade requirement for subsequent spheroidization, and cracking is easy during cold forming. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an optimized coiling temperature process for cold heading steel that eliminates the need for annealing. This process offers advantages such as cost reduction, energy saving, and reduced environmental pressure, thus solving the problems of high costs and significant environmental impact associated with traditional processes.

[0005] (II) Technical Solution To achieve the above-mentioned goals of cost reduction and consumption reduction, and to alleviate environmental pressure, the present invention provides the following technical solution: an optimized coiling temperature process for annealed cold heading steel, including S1 pre-rolling preparation, S2 heating process, S3 rolling process control, S4 controlled cooling process optimization, S5 coiling and heat preservation process, and S6 quality inspection and feedback. The S1 pre-rolling preparation includes S101 equipment pretreatment, S102 billet preparation, and S103 preheating requirements. Among them, the S2 heating process includes S201 heating temperature, S202 holding time, and S203 furnace exit control; Among them, the S3 rolling process control includes S301 finishing rolling temperature, S302 sizing temperature and S303 wire drawing temperature; Among them, the S4 cooling process optimization includes S401 roller speed control, S402 heat insulation cover control and S403 cooling rate control. Among them, the S5 winding and insulation process includes S501 winding temperature, S502 insulation corridor treatment and S503 exit corridor control. Among them, S6 quality inspection and feedback includes S601 mechanical property inspection, S602 metallographic structure inspection, S603 surface quality inspection and S604 feedback adjustment.

[0006] Preferably, the S101 equipment pretreatment involves: preheating the insulated corridor at a temperature of 280-420℃ to ensure uniform temperature within the corridor without significant temperature differences; checking the sealing of the LCC air-cooled roller conveyor and insulation cover, sealing any gaps, and installing densely packed rollers in the drop section to reduce the number of pulls at the tail end; and turning off the air-cooled line fan to ensure that the fan is fully shut off.

[0007] Preferably, the S102 steel billet is prepared as follows: a steel billet with a carbon content of 0.32-0.38%, a silicon content of 0.16-0.24%, a manganese content of 0.65-0.75%, a chromium content of 0.85-1.05%, and a molybdenum content of 0.14-0.18% is selected. The internal composition of the steel billet is uniform and there is no serious segregation. The surface of the steel billet is free of cracks and iron oxide scale defects.

[0008] Preferably, the preheating requirement of S103 is as follows: before rolling, the LCC roller conveyor and insulation cover are preheated with delayed cooling steel to ensure that the surface temperature of the roller conveyor is ≥250℃ and the ambient temperature inside the insulation cover is ≥280℃.

[0009] Preferably, the heating temperature of S201 is: the steel billet is sent into the heating furnace and the heating temperature is controlled at 980-1060℃ to ensure that the steel billet is completely austenitized and to avoid local incomplete melting. S202 holding time: Adjust the holding time according to the billet specifications. For specifications of Φ6.5-12mm, the holding time is 80-120min; for specifications of Φ12-52mm, the holding time is 100-180min to ensure uniform diffusion of components and reduce segregation of microstructure. S203 Exit Control: Exit temperature fluctuations are controlled within ±30℃ to avoid sudden temperature rises and falls that could cause cracks on the billet surface.

[0010] Preferably, the finishing rolling temperature of S301 is controlled at 880-930℃ to ensure good metal plasticity during rolling and reduce rolling force. S302 Reduction Sizing Temperature: The reduction sizing inlet temperature is controlled at 800-870℃. By adjusting the roll speed, the dimensional accuracy of the rolled workpiece is ensured, and the dimensional tolerance is controlled within ±0.15mm. S303 coiling temperature: The coiling temperature is controlled at 770-820℃. The Wob function is canceled during the coiling process to avoid the coil protruding and causing local cooling to be too fast. After coiling, the coil is neatly arranged without obvious misalignment or pulling.

[0011] Preferably, the speed control of the S401 roller conveyor is as follows: the speed of the first section of the LCC air-cooled roller conveyor is controlled at 0.10-0.28 m / s, and the speed of each subsequent section is adjusted to 0.15-0.45 m / s according to the specifications, to ensure that the rolled piece has sufficient residence time on the roller conveyor and that the phase transformation is complete; S402 thermal insulation cover control: Open 1-3 thermal insulation covers first, and close the rest. Seal the gaps between thermal insulation covers with thermal insulation cotton to reduce heat loss. Adjust the number of thermal insulation covers to be opened according to the ambient temperature. The number of thermal insulation covers to be opened can be reduced in winter and increased in summer. S403 Cooling Rate Control: By adjusting the roller speed and the state of the insulation cover, the cooling rate of the rolled piece is controlled between 0.2-5.5℃ / s. When the cooling rate is 0.2-1.0℃ / s, a microstructure mainly composed of ferrite and pearlite is obtained; when the cooling rate is 1.0-5.5℃ / s, the bainite content is strictly controlled to avoid the formation of martensite.

[0012] Preferably, the winding temperature of S501 is: the temperature of the overlapping point is controlled at 630-750℃ and the temperature of the non-overlapping point is controlled at 600-720℃ during winding, so as to avoid the coil being squeezed or deformed during the winding process.

[0013] Preferably, the S502 insulation corridor treatment involves: after winding, the wire rod is fed into the insulation corridor, the temperature inside the corridor is controlled at 300-430℃, and the insulation time is 60-200 minutes; during the insulation process, the doors at both ends of the corridor are closed to ensure that the temperature inside the corridor is stable and there is no temperature fluctuation caused by air convection. S503 Out-of-Cavity Control: When the wire rod exits the insulation corridor, the temperature is controlled at 450-600℃ to avoid rapid cooling after high temperature exiting the corridor, which would produce a hard and brittle structure.

[0014] Preferably, the mechanical property test of S601 involves randomly selecting samples from the head, tail, and middle parts of the wire rod, testing for tensile strength ≤880MPa, tensile strength fluctuation within the same coil ≤150MPa, and no breakage when the first drawing reduction rate is 20-45%. S602 metallographic structure test: The metallographic structure is mainly ferrite + pearlite, with a small amount of bainite allowed, and no obvious martensite structure; the spheroidization level reaches 4.5-6.0. S603 Surface Quality Inspection: The thickness of the decarburized layer on the surface of the wire rod is ≤0.12mm, with no residual iron oxide scale, cracks, or scratches. S604 Feedback Adjustment: Adjust process parameters according to test results. If the tensile strength is too high, the spinning temperature can be reduced by 5-15℃ or the holding time can be increased by 20-30min. If the martensite content in the microstructure exceeds the standard, the cooling rate can be reduced by 0.3-1.0℃ / s.

[0015] (III) Beneficial Effects Compared with the prior art, the present invention provides an optimized coiling temperature process for reducing the need for annealing and cold heading steel, which has the following beneficial effects: 1. This optimized coiling temperature process for cold heading steel with reduced annealing achieves cost reduction and consumption reduction, alleviating environmental pressure. Through the core design of "reduced annealing," it eliminates 1-2 spheroidizing annealing steps in the traditional process, reducing annealing furnace energy consumption (based on an average daily annealing capacity of 180 tons, monthly savings of 30-50% in electricity or natural gas consumption); it also reduces the number of pickling operations (reduced frequency of cold acid pickling for specifications below Φ16mm and shot blasting for specifications above Φ16mm), reducing acidic wastewater discharge by 40-60%, and lowering environmental treatment costs by more than 30%; the production cycle is shortened from the traditional 3-5 days to 1-2 days, improving the capital turnover efficiency of downstream customers.

[0016] 2. This optimized coiling temperature process for cold heading steel that eliminates the need for annealing achieves improved mechanical properties and enhanced microstructure stability. Through precise cooling control (cooling rate 0.2-5.5℃ / s) and heat preservation corridor regulation (temperature 300-430℃, heat preservation time 60-200min), the tensile strength of the wire rod is stably controlled at ≤880MPa, with a fluctuation of ≤150MPa within the same coil, meeting the customer's core requirement of ≤850MPa. The microstructure is mainly composed of ferrite and pearlite (accounting for over 90% at a cooling rate of 0.2-1.0℃ / s), containing only a small amount of bainite and no obvious martensite. The area reduction rate of the first drawing pass can be increased to 20-45%, and a spheroidization level of 4.5-6.0 can be achieved without additional grain crushing treatment. The cold forming crack rate is reduced to below 1%.

[0017] 3. The optimized coiling temperature process for annealed cold heading steel reduces the need for annealing. This process improves equipment utilization and enhances process adaptability. The LCC air-cooled roller conveyor drop section is equipped with closely spaced rollers and gaps are sealed. The number of coils for pulling the tail wire is reduced from 15-20 to 5-8, shearing loss is reduced by 10-15%, and the yield is increased to over 95%. The insulated corridor is preheated to 280-420℃, and with the winter and summer differentiated insulation cover control (1-2 in winter, 2-3 in summer), it can be adapted to the production of Φ6.5-52mm full specification wire rod, and the tensile strength fluctuation in winter is controlled within 850-900MPa, solving the problem of the influence of ambient temperature. The WOB function of the spinning machine is cancelled, and the speed of the first section of the roller conveyor is controlled at 0.10-0.28m / s. The uniformity of the coil loops is improved by 80%, avoiding local overcooling and the formation of hard structures, thus reducing the defect rate.

[0018] 4. The optimized coiling temperature process for annealed cold heading steel meets market demands and enhances product competitiveness. The optimized product fully satisfies downstream customers' core requirements for "ferrite + pearlite microstructure" and "largest first-pass drawing volume." Compared with traditional process products, the drawing fracture rate is reduced from 10-15% to below 1%, and customer processing efficiency is improved by 25-30%. At the same time, the tensile strength stability (pass rate ≥85%) is close to the international advanced level, which can replace some imported materials and help enterprises increase their market share in the high-end cold heading steel market by 15-20%, thus coping with the competitive pressure from leading steel mills. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] This solution provides a technical approach, specifically an optimized coiling temperature process for reducing or eliminating the need for annealed cold heading steel, comprising the following steps: S1 Preparation before rolling: S101 Equipment Pretreatment: Preheat the insulated corridor, controlling the preheating temperature at 280-420℃ to ensure uniform temperature within the corridor with no significant temperature difference; check the sealing of the LCC air-cooled roller conveyor and insulation cover, seal any gaps, and install densely packed rollers in the drop section to reduce the number of pulls at the tail end; turn off the air-cooled line fan, ensuring the fan is fully shut off; S102 steel billet preparation: Select steel billets with carbon content of 0.32-0.38%, silicon content of 0.16-0.24%, manganese content of 0.65-0.75%, chromium content of 0.85-1.05%, and molybdenum content of 0.14-0.18%. The internal composition of the steel billet should be uniform without serious segregation; the surface of the steel billet should be free of cracks and iron oxide scale defects. S103 preheating requirements: Before rolling, the LCC roller conveyor and insulation cover shall be preheated with delayed cooling steel to ensure that the surface temperature of the roller conveyor is ≥250℃ and the ambient temperature inside the insulation cover is ≥280℃. S2 heating process: S201 heating temperature: The steel billet is sent into the heating furnace and the heating temperature is controlled at 980-1060℃ to ensure that the steel billet is completely austenitized and to avoid local incomplete melting. S202 holding time: Adjust the holding time according to the billet specifications. For specifications of Φ6.5-12mm, the holding time is 80-120min; for specifications of Φ12-52mm, the holding time is 100-180min to ensure uniform diffusion of components and reduce segregation of microstructure. S203 Exit Control: Exit temperature fluctuations are controlled within ±30℃ to avoid sudden temperature rises and falls that could cause cracks on the billet surface. S3 Rolling Process Control: S301 Finishing Rolling Temperature: The finishing rolling inlet temperature is controlled at 880-930℃ to ensure good metal plasticity during rolling and reduce rolling force; S302 Reduction Sizing Temperature: The reduction sizing inlet temperature is controlled at 800-870℃. By adjusting the roll speed, the dimensional accuracy of the rolled workpiece is ensured, and the dimensional tolerance is controlled within ±0.15mm. S303 coiling temperature: The coiling temperature is controlled at 770-820℃. The Wob function is canceled during the coiling process to avoid the coil protruding and causing localized cooling to be too fast. After coiling, the coil loops are neat and there is no obvious misalignment or pulling phenomenon. S4 cooling process optimization: S401 Roller Conveyor Speed ​​Control: The speed of the first section of the LCC air-cooled roller conveyor is controlled at 0.10-0.28m / s, and the speed of subsequent sections is adjusted to 0.15-0.45m / s according to the specifications to ensure that the rolled workpiece has sufficient residence time on the roller conveyor and complete phase transformation; S402 thermal insulation cover control: Open 1-3 thermal insulation covers first, and close the rest. Seal the gaps between thermal insulation covers with thermal insulation cotton to reduce heat loss. Adjust the number of thermal insulation covers to be opened according to the ambient temperature. The number of thermal insulation covers to be opened can be reduced in winter and increased in summer. S403 Cooling Rate Control: By adjusting the roller speed and the state of the insulation cover, the cooling rate of the rolled piece is controlled between 0.2-5.5℃ / s. When the cooling rate is 0.2-1.0℃ / s, a microstructure mainly composed of ferrite and pearlite is obtained; when the cooling rate is 1.0-5.5℃ / s, the bainite content is strictly controlled to avoid the formation of martensite. S5 winding and insulation process: S501 winding temperature: During winding, the temperature of the overlapping point should be controlled at 630-750℃, and the temperature of the non-overlapping point should be controlled at 600-720℃. Avoid coil compression and deformation during winding. S502 Insulated Corridor Treatment: After winding, the wire rod is fed into the insulated corridor. The temperature inside the corridor is controlled at 300-430℃, and the insulation time is 60-200 minutes. During the insulation process, the doors at both ends of the corridor are closed to ensure that the temperature inside the corridor is stable and there is no temperature fluctuation caused by air convection. S503 Out-of-Cavity Control: When the wire rod exits the insulation corridor, the temperature is controlled at 450-600℃ to avoid rapid cooling after high-temperature exit and the formation of hard and brittle structures. S6 Quality Inspection and Feedback: S601 Mechanical property testing: Randomly select samples from the head, tail and middle parts of the wire rod, and test the tensile strength ≤880MPa, the tensile strength fluctuation within the same coil ≤150MPa; no breakage occurs when the surface area reduction rate of the first drawing is 20-45%; S602 metallographic structure test: The metallographic structure is mainly ferrite + pearlite, with a small amount of bainite allowed, and no obvious martensite structure; the spheroidization level reaches 4.5-6.0. S603 Surface Quality Inspection: The thickness of the decarburized layer on the surface of the wire rod is ≤0.12mm, with no residual iron oxide scale, cracks, or scratches. S604 Feedback Adjustment: Adjust process parameters according to test results. If the tensile strength is too high, the spinning temperature can be reduced by 5-15℃ or the holding time can be increased by 20-30min. If the martensite content in the microstructure exceeds the standard, the cooling rate can be reduced by 0.3-1.0℃ / s. Furthermore, this process achieves cost reduction and consumption reduction, alleviating environmental pressure. Through the core design of "reduced or eliminated annealing," it eliminates 1-2 spheroidizing annealing steps in the traditional process, reducing annealing furnace energy consumption (based on an average daily annealing capacity of 180 tons, monthly savings of 30-50% in electricity or natural gas consumption); at the same time, it reduces the number of pickling operations (reducing the frequency of cold acid pickling for specifications below Φ16mm and shot blasting for specifications above Φ16mm), reducing acidic wastewater discharge by 40-60%, and lowering environmental treatment costs by more than 30%; the production cycle is shortened from the traditional 3-5 days to 1-2 days, improving the capital turnover efficiency of downstream customers; Furthermore, this process optimizes mechanical properties and improves structural stability. Through precise cooling control (cooling rate 0.2-5.5℃ / s) and heat preservation corridor regulation (temperature 300-430℃, heat preservation time 60-200min), the tensile strength of the wire rod is stably controlled at ≤880MPa, with a fluctuation of ≤150MPa within the same coil, meeting the customer's core requirement of ≤850MPa. The microstructure is mainly composed of ferrite and pearlite (accounting for over 90% at a cooling rate of 0.2-1.0℃ / s), containing only a small amount of bainite and no obvious martensite. The area reduction rate of the first drawing pass can be increased to 20-45%, and a spheroidization level of 4.5-6.0 can be achieved without additional grain crushing treatment. The cold forming crack rate is reduced to below 1%. Furthermore, this process improves equipment utilization and enhances process adaptability. The LCC air-cooled roller conveyor drop section is equipped with closely spaced rollers and gaps are sealed. The number of coils for pulling the tail wire is reduced from 15-20 to 5-8, shearing loss is reduced by 10-15%, and the yield rate is increased to over 95%. The insulated corridor is preheated to 280-420℃, and with the winter and summer differentiated insulation cover control (1-2 in winter, 2-3 in summer), it can be adapted to the production of Φ6.5-52mm full specification wire rod, and the tensile strength fluctuation in winter is controlled within 850-900MPa, solving the problem of the influence of ambient temperature. The WOB function of the spinning machine is cancelled, and the speed of the first section of the roller conveyor is controlled at 0.10-0.28m / s. The uniformity of the coil loops is improved by 80%, avoiding local overcooling and the formation of hard structures, thus reducing the defect rate. Furthermore, this process aligns with market demands and enhances product competitiveness. The optimized product fully meets downstream customers' core requirements for "ferrite + pearlite microstructure" and "largest first-pass drawing volume." Compared to traditional process products, the drawing fracture rate has been reduced from 10-15% to below 1%, improving customer processing efficiency by 25-30%. At the same time, the tensile strength stability (pass rate ≥85%) is close to the international advanced level, which can replace some imported materials and help enterprises increase their market share in the high-end cold heading steel market by 15-20%, thus coping with competitive pressure from leading steel mills.

[0021] 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 coiling temperature optimization process for reducing the need for annealing in cold heading steel, comprising S1 pre-rolling preparation, S2 heating process, S3 rolling process control, S4 controlled cooling process optimization, S5 coiling and holding process, and S6 quality inspection and feedback, characterized in that: The preparations before rolling S1 include S101 equipment pretreatment, S102 billet preparation and S103 preheating requirements; Among them, the S2 heating process includes S201 heating temperature, S202 holding time, and S203 furnace exit control; Among them, the S3 rolling process control includes S301 finishing rolling temperature, S302 sizing temperature and S303 wire drawing temperature; Among them, the S4 cooling process optimization includes S401 roller speed control, S402 heat insulation cover control and S403 cooling rate control. Among them, the S5 winding and insulation process includes S501 winding temperature, S502 insulation corridor treatment and S503 exit corridor control. Among them, S6 quality inspection and feedback includes S601 mechanical property inspection, S602 metallographic structure inspection, S603 surface quality inspection and S604 feedback adjustment.

2. The optimized coiling temperature process for reducing annealing in cold heading steel according to claim 1, characterized in that: The S101 equipment pretreatment involves preheating the insulated corridor at a temperature of 280-420℃ to ensure uniform temperature within the corridor without significant temperature differences; checking the sealing of the LCC air-cooled roller conveyor and insulation cover, sealing any gaps, and installing densely packed rollers in the drop section to reduce the number of pulls at the tail end; and turning off the air-cooled line fan to ensure it is fully shut off.

3. The optimized coiling temperature process for reducing annealing in cold heading steel according to claim 1, characterized in that: The S102 steel billet preparation: Select steel billets with carbon content of 0.32-0.38%, silicon content of 0.16-0.24%, manganese content of 0.65-0.75%, chromium content of 0.85-1.05%, and molybdenum content of 0.14-0.18%. The internal composition of the steel billet is uniform and there is no serious segregation. The surface of the steel billet is free of cracks and iron oxide scale defects.

4. The optimized coiling temperature process for reducing annealing in cold heading steel according to claim 1, characterized in that: The S103 preheating requirements are as follows: Before rolling, the LCC roller conveyor and insulation cover are preheated with delayed cooling steel to ensure that the surface temperature of the roller conveyor is ≥250℃ and the ambient temperature inside the insulation cover is ≥280℃.

5. The optimized coiling temperature process for reducing annealing in cold heading steel according to claim 1, characterized in that: The S201 heating temperature is as follows: the steel billet is sent into the heating furnace and the heating temperature is controlled at 980-1060℃ to ensure that the steel billet is completely austenitized and to avoid local incomplete melting. S202 holding time: Adjust the holding time according to the billet specifications. For specifications of Φ6.5-12mm, the holding time is 80-120min; for specifications of Φ12-52mm, the holding time is 100-180min to ensure uniform diffusion of components and reduce segregation of microstructure. S203 Exit Control: Exit temperature fluctuations are controlled within ±30℃ to avoid sudden temperature rises and falls that could cause cracks on the billet surface.

6. The optimized coiling temperature process for reducing annealing in cold heading steel according to claim 1, characterized in that: The S301 finishing rolling temperature is controlled at 880-930℃ to ensure good metal plasticity during rolling and reduce rolling force. S302 Reduction Sizing Temperature: The reduction sizing inlet temperature is controlled at 800-870℃. By adjusting the roll speed, the dimensional accuracy of the rolled workpiece is ensured, and the dimensional tolerance is controlled within ±0.15mm. S303 coiling temperature: The coiling temperature is controlled at 770-820℃. The Wob function is canceled during the coiling process to avoid the coil protruding and causing localized cooling to be too fast. After spinning, the coils are neatly arranged with no obvious misalignment or fraying.

7. The optimized coiling temperature process for reducing annealing in cold heading steel according to claim 1, characterized in that: The speed control of the S401 roller conveyor: the speed of the first section of the LCC air-cooled roller conveyor is controlled at 0.10-0.28m / s, and the speed of subsequent sections is adjusted to 0.15-0.45m / s according to the specifications to ensure that the rolled workpiece has sufficient residence time on the roller conveyor and that the phase transformation is complete; S402 thermal insulation cover control: Open 1-3 thermal insulation covers first, and close the rest. Seal the gaps between thermal insulation covers with thermal insulation cotton to reduce heat loss. Adjust the number of thermal insulation covers to be opened according to the ambient temperature. The number of thermal insulation covers to be opened can be reduced in winter and increased in summer. S403 Cooling Rate Control: By adjusting the roller speed and the state of the insulation cover, the cooling rate of the rolled piece is controlled between 0.2-5.5℃ / s. When the cooling rate is 0.2-1.0℃ / s, a microstructure mainly composed of ferrite and pearlite is obtained; when the cooling rate is 1.0-5.5℃ / s, the bainite content is strictly controlled to avoid the formation of martensite.

8. The optimized coiling temperature process for reducing annealing in cold heading steel according to claim 1, characterized in that: The S501 winding temperature is as follows: the temperature at the overlap point is controlled at 630-750℃, and the temperature at the non-overlap point is controlled at 600-720℃. During the winding process, the coil should be protected from compression and deformation.

9. The optimized coiling temperature process for reducing annealing in cold heading steel according to claim 1, characterized in that: The S502 insulation corridor treatment: After winding, the wire rod is sent into the insulation corridor. The temperature inside the corridor is controlled at 300-430℃, and the insulation time is 60-200 minutes. During the insulation process, the doors at both ends of the corridor are closed to ensure that the temperature inside the corridor is stable and there is no temperature fluctuation caused by air convection. S503 Out-of-Cavity Control: When the wire rod exits the insulation corridor, the temperature is controlled at 450-600℃ to avoid rapid cooling after high temperature exiting the corridor, which would produce a hard and brittle structure.

10. The optimized coiling temperature process for reducing annealing in cold heading steel according to claim 1, characterized in that: The mechanical properties of S601 were tested as follows: samples were randomly selected from the head, tail and middle parts of the wire rod, and the tensile strength was tested to be ≤880MPa, and the tensile strength fluctuation within the same coil was ≤150MPa; no breakage was observed when the surface area reduction rate of the first drawing was 20-45%. S602 metallographic structure test: The metallographic structure is mainly ferrite + pearlite, with a small amount of bainite allowed, and no obvious martensite structure; the spheroidization level reaches 4.5-6.

0. S603 Surface Quality Inspection: The thickness of the decarburized layer on the surface of the wire rod is ≤0.12mm, with no residual iron oxide scale, cracks, or scratches. S604 Feedback Adjustment: Adjust process parameters according to test results. If the tensile strength is too high, the spinning temperature can be reduced by 5-15℃ or the holding time can be increased by 20-30min. If the martensite content in the microstructure exceeds the standard, the cooling rate can be reduced by 0.3-1.0℃ / s.