Production method of hard cold-rolled sheet with high processability
By employing low-temperature annealing and leveling processes after cold rolling, the problem of balancing hardness and processing performance in hardened cold-rolled sheets has been solved, resulting in the production of high-hardness, high-processability hardened cold-rolled sheets suitable for precision electronics, high-end automobiles, and medical device parts, thereby reducing production costs.
Patent Information
- Application Number
- CN202511034490.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2025-11-21
AI Technical Summary
In the current production of hardened cold-rolled steel sheets, it is difficult to balance hardness and processing performance. Traditional methods require the addition of expensive alloying elements or improper annealing processes, which can lead to cracks and fractures in complex processing, making it difficult to meet the requirements of precision electronics, high-end automobiles and medical fields.
The process involves cold rolling followed by low-temperature annealing, including holding at 430–500℃ for 10–15 hours with furnace cooling, gradual air cooling, and water cooling, combined with two leveling processes to control the rolling force, producing high-hardness, high-processability cold-rolled sheets.
It significantly improves the processing performance of hardened cold-rolled sheets, reduces production costs, and prevents cracks and fractures in products during complex processing. It is suitable for precision electronic components, high-end automobiles, and medical device parts.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of metal material processing and relates to a production method of high-processability hard rolled cold-rolled plate. BACKGROUND
[0002] In the production and application of cold-rolled plates, the hard rolled cold-rolled plate has a wide range of applications in many fields due to its high strength and hardness. However, the problem of "difficulty in balancing hardness and processability" still exists in the production of the existing hard rolled cold-rolled plate. The traditional process either increases the cost by adding expensive alloy elements to improve the performance or causes the product to easily crack, break and other situations during complex processing (such as precision stamping and multiple bending) due to unreasonable annealing process, which is difficult to meet the strict requirements of precision electronics, high-end automobiles, medical treatment and other fields on materials. Therefore, it is urgent to develop a new production method to produce hard rolled cold-rolled plates with high hardness and high processability while reducing production costs. SUMMARY
[0003] To solve the above technical problems, the application provides a production method of high-processability hard rolled cold-rolled plate, which only needs one low-temperature annealing treatment after the cold rolling process, so that the steel plate can significantly improve its processability while maintaining high hardness characteristics, and finally produce high-hardness high-processability hard rolled cold-rolled plates suitable for precision electronic component housings, high-end automobile and medical instrument accessories.
[0004] To achieve the above application purposes, the technical scheme adopted by the application is: A production method of high-processability hard rolled cold-rolled plate, comprising hot-rolled steel coil pickling, cold rolling, low-temperature annealing and leveling processes. The low-temperature annealing process is that the steel coil is heated to 430-500 DEG C after cold rolling, and is kept for 10-15 h; then it is cooled to 380-420 DEG C in the furnace, and is air-cooled to 340-360 DEG C at a speed of 40-50 DEG C / h, and is cooled to 240-260 DEG C in the furnace, and finally is water-cooled at a speed of 10-15 DEG C / h.
[0005] Further, the low-temperature annealing process is that the steel coil is heated to 430-500 DEG C at a speed of 90-110 DEG C / h after cold rolling.
[0006] Further, the low-temperature annealing process is that the steel coil is discharged after water-cooled to 70-90 DEG C.
[0007] Further, the leveling process adopts two passes of leveling, and the rolling force of the first pass is controlled at 400-900 kN, and the rolling force of the second pass is controlled at 300-500 kN.
[0008] Further, the chemical composition of the hot-rolled steel coil is as follows in terms of mass percentage: C: 0.02-0.09%, Si≤0.03%, Mn: 0.15-0.35%, P≤0.02%, S≤0.015%, Als≤0.2%, and the balance of Fe and inevitable impurities.
[0009] The low-temperature annealing process is a key process of the application, and the rolled steel is kept at 430-500 DEG C for 10-15 hours after rolling. During the heating and keeping process, the internal structure of the steel changes, the residual stress generated in the cold rolling process is eliminated, and the processing performance of the steel is improved. After the keeping process, the gradual cooling method is used to accurately control the structure transformation of the steel, so that the internal structure of the steel is more uniform, the elongation is increased by more than 1.4% than the conventional method, and the requirement of 180-degree multiple bending (≥5 times) is met, and the performance of the product is further improved.
[0010] The application innovatively adopts the process path of "cold rolling + single precise low-temperature annealing", which successfully breaks through the technical problem of "difficulty in balancing hardness and processing performance" in the production of traditional hard-rolled cold-rolled plates. After giving the steel a basic hardness through the cold rolling process, only one low-temperature annealing treatment is needed to significantly improve the processing performance while maintaining high hardness characteristics, and finally produce high-hardness high-processing-performance hard-rolled cold-rolled plates suitable for precise electronic component housings, high-end automobile and medical instrument accessories.
[0011] Compared with the traditional production process, the application does not need to add expensive alloy elements such as nickel and manganese to improve the performance, which greatly reduces the production cost from the root. At the same time, the performance fluctuation problem caused by the complex process and improper composition adjustment in the traditional process is avoided, and the probability of product cracking and breaking in the production and processing process of downstream customers is significantly reduced, which further improves the market competitiveness of the product. DETAILED DESCRIPTION
[0012] The following examples use ordinary SPCC material hot-rolled steel coil as raw material, and the chemical composition is as follows in terms of mass percentage: C: 0.02-0.09%, Si≤0.03%, Mn: 0.15-0.35%, P≤0.02%, S≤0.015%, Als≤0.2%, and the balance of Fe and inevitable impurities. Example 1
[0013] A hot-rolled steel coil with a thickness of 3.0 mm is selected as the initial raw material, and the chemical composition (mass percentage) is C: 0.08%, Si: 0.024%, Mn: 0.32%, P: 0.013%, S: 0.011%, Als: 0.04%, and the balance of Fe and inevitable impurities. The production method includes hot-rolled steel coil pickling, cold rolling, low-temperature annealing, and flattening processes; the parameters of each process are controlled as follows: Pickling process: 8% hydrochloric acid pickling solution was used, and the pickling time was 35s; Cold rolling process: the thickness of the steel plate was gradually rolled to 0.25mm through 5 passes, and the cold rolling reduction was 91.7%; Low temperature annealing process: after rolling, the steel coil was heated to 480℃ at a speed of 110℃ / h, and kept for 13 hours, then cooled to 420℃ in the furnace, and then air cooled to 360℃ at a speed of 50℃ / h, and then cooled to 245℃ in the furnace, and finally water cooled at a speed of 13℃ / h until the temperature was cooled to 70℃, and then discharged from the furnace; Leveling process: after low temperature annealing, the steel coil was leveled through 2 passes, and the rolling force of the first pass was controlled at 600kN, and the rolling force of the second pass was controlled at 400kN.
[0014] Comparative Example 1: A hard rolled cold rolled plate with a thickness of 0.25mm was produced by a conventional method, and high temperature annealing treatment was usually carried out after cold rolling. The specific steps are as follows: after cold rolling, the steel coil is heated to 600-700℃ at a speed of 120-150℃ / h, and kept for 8-12 hours, and then cooled to below 300℃ in the furnace after the end of the heat preservation, and then discharged from the furnace. Although this high temperature annealing treatment can eliminate the stress generated during cold rolling to a certain extent, the high annealing temperature will cause the hardness of the steel to decrease obviously. In order to make up for the loss of hardness and ensure that the product performance meets the standard, expensive alloying elements such as Ni (1%-4%) and Mn (0.5%-1.5%) must be added in the steelmaking stage, which undoubtedly greatly increases the production cost, and may also adversely affect the processing performance of the steel due to improper control of the alloying element ratio.
[0015] Table 1: Performance comparison of products produced by Example 1 and Comparative Example 1
[0016] The hard rolled cold rolled plate obtained in this example is used to produce a certain common multiple bending processing electronic component on the market, which requires 180° bending times ≥5 times, and the qualified product rate can reach 99.8%; the hard rolled cold rolled plate produced by Comparative Example 1 has serious bending fracture during production, and basically cannot be used. Example 2
[0017] A hot rolled steel coil with a thickness of 2.5mm was selected as the initial raw material, and its chemical composition (mass percent) was C: 0.05%, Si: 0.014%, Mn: 0.29%, P: 0.012%, S: 0.009%, Als: 0.04%, and the balance was Fe and unavoidable impurities. Its production method includes hot rolled steel coil pickling, cold rolling, low temperature annealing, and leveling process; the parameters of each process are controlled as follows: Pickling process: 8% hydrochloric acid pickling solution was used, and the pickling time was 40s; Cold rolling process: the thickness of the steel plate was gradually rolled to 0.26 mm through 5 passes, and the cold rolling reduction was 89.6%; Low temperature annealing process: the steel coil was heated to 450℃ at a speed of 105℃ / h, kept for 12 hours, furnace-cooled to 397℃, air-cooled to 355℃ at a speed of 42℃ / h, then furnace-cooled to 250℃, and finally water-cooled at a speed of 10℃ / h until the temperature was lowered to 73℃, and the coil was discharged; Tempering process: the steel coil after low temperature annealing was tempered through 2 passes, and the rolling force was controlled at 550 kN in the first pass and 350 kN in the second pass.
[0018] Comparative Example 2: a hard rolled cold rolled plate with a thickness of 0.26 mm was produced by the conventional method described in Comparative Example 1.
[0019] Table 2: comparison of the properties of the products produced in Example 2 and Comparative Example 2
[0020] The hard rolled cold rolled plate obtained in this example was used to produce a certain common multiple bending processing electronic component on the market, which required 180° bending for ≥5 times, and the qualified product rate could reach 99.8%; the hard rolled cold rolled plate produced in Comparative Example 1 had serious bending fracture during production and could not be used basically. Example 3
[0021] A hot-rolled steel coil with a thickness of 3.0 mm was selected as the initial raw material, and its chemical composition (mass percent) was C: 0.02%, Si: 0.018%, Mn: 0.19%, P: 0.011%, S: 0.010%, Als: 0.04%, and the balance was Fe and unavoidable impurities. Its production method included hot-rolled steel coil pickling, cold rolling, low temperature annealing, and tempering processes; the parameters of each process were controlled as follows: Pickling process: 8% hydrochloric acid pickling solution was used, and the pickling time was 35 s; Cold rolling process: the thickness of the steel plate was gradually rolled to 0.32 mm through 5 passes, and the cold rolling reduction was 89.3%; Low temperature annealing process: the steel coil was heated to 495℃ at a speed of 100℃ / h, kept for 15 hours, furnace-cooled to 400℃, air-cooled to 350℃ at a speed of 47℃ / h, then furnace-cooled to 260℃, and finally water-cooled at a speed of 15℃ / h until the temperature was lowered to 90℃, and the coil was discharged; Tempering process: the steel coil after low temperature annealing was tempered through 2 passes, and the rolling force was controlled at 460 kN in the first pass and 480 kN in the second pass.
[0022] Comparative Example 3: a hard rolled cold rolled plate with a thickness of 0.32 mm was produced by the conventional method described in Comparative Example 1.
[0023] Table 3: Performance comparison of products produced by Example 3 and Comparative Example 3
[0024] The hard rolled cold-rolled sheet obtained in this example is used to produce a certain common multiple bending processing electronic component on the market, which requires 180° bending times ≥5 times, and the qualified product rate can reach 99.8%; the hard rolled cold-rolled sheet produced by Comparative Example 1 has serious bending fracture during production process and basically cannot be used. Example 4
[0025] A hot-rolled steel coil with a thickness of 2.75 mm is selected as the initial raw material, and the chemical composition (mass percentage) is C: 0.03%, Si: 0.018%, Mn: 0.19%, P: 0.011%, S: 0.010%, Als: 0.04%, and the balance is Fe and unavoidable impurities. Its production method includes hot-rolled steel coil pickling, cold rolling, low temperature annealing, and leveling process; the parameters of each process are controlled as follows: Pickling process: 8% hydrochloric acid pickling solution is used, and the pickling time is 35s; Cold rolling process: through 5 passes of rolling, the thickness of the steel plate is gradually rolled to 0.35 mm, and the cold rolling reduction rate is 87.3%; Low temperature annealing process: after rolling, the coil is heated to 500℃ at a rate of 90℃ / h, and the temperature is maintained for 15 hours, and then cooled to 380℃, and then air-cooled to 360℃ at a rate of 40℃ / h, and then furnace-cooled to 260℃, and finally water-cooled at a rate of 12℃ / h until the temperature is cooled to 85℃, and then discharged from the furnace; Leveling process: after low temperature annealing, the coil is leveled by 2 passes, and the rolling force of the first pass is controlled at 900kN, and the rolling force of the second pass is controlled at 500kN.
[0026] Comparative Example 4: A hard rolled cold-rolled sheet with a thickness of 0.35 mm is produced by the conventional method described in Comparative Example 1.
[0027] Table 4: Performance comparison of products produced by Example 4 and Comparative Example 4
[0028] The hard rolled cold-rolled sheet obtained in this example is used to produce a certain common multiple bending processing electronic component on the market, which requires 180° bending times ≥5 times, and the qualified product rate can reach 99.8%; the hard rolled cold-rolled sheet produced by Comparative Example 1 has serious bending fracture during production process and basically cannot be used. Example 5
[0029] The hot-rolled steel coil with a thickness of 2.5 mm is selected as the initial raw material, and the chemical composition (mass percentage) is C: 0.03%, Si: 0.018%, Mn: 0.19%, P: 0.011%, S: 0.010%, Als: 0.04%, and the balance is Fe and inevitable impurities. The production method includes pickling of the hot-rolled steel coil, cold rolling, low-temperature annealing, and flattening process; the process parameters are controlled as follows: Pickling process: 8% hydrochloric acid pickling solution is used, and the pickling time is 35 s; Cold rolling process: through 4 passes of rolling, the thickness of the steel plate is gradually rolled to 0.37 mm, and the cold rolling reduction is 85.2%; Low-temperature annealing process: after rolling, the coil is heated to 430℃ at a rate of 110℃ / h, and the temperature is maintained for 10 hours. The furnace is cooled to 390℃, and then air-cooled to 344℃ at a rate of 48℃ / h. The furnace is cooled to 240℃, and finally water-cooled at a rate of 15℃ / h until the temperature is cooled to 90℃, and the coil is discharged; Flattening process: after low-temperature annealing, the coil is flattened by 2 passes, and the rolling force is controlled at 650 kN in the first pass and 300 kN in the second pass.
[0030] Comparative Example 5: The conventional method described in Comparative Example 1 is used to produce a hard-rolled cold-rolled plate with a thickness of 0.37 mm.
[0031] Table 5: Performance comparison of products produced in Example 5 and Comparative Example 5
[0032] The hard-rolled cold-rolled plate obtained in this example is used to produce high-end automotive brake pad products on the market, which meets the requirements of high hardness and high processing performance, and the 180° bending frequency is required to be ≥5 times, and the qualified product rate can reach 99.5%. The hard-rolled cold-rolled plate produced in Comparative Example 5 has a qualified product rate of only 96.1%. Example 6
[0033] The hot-rolled steel coil with a thickness of 3.0 mm is selected as the initial raw material, and the chemical composition (mass percentage) is C: 0.09%, Si: 0.019%, Mn: 0.32%, P: 0.014%, S: 0.012%, Als: 0.05%, and the balance is Fe and inevitable impurities. The production method includes pickling of the hot-rolled steel coil, cold rolling, low-temperature annealing, and flattening process; the process parameters are controlled as follows: Pickling process: 8% hydrochloric acid pickling solution is used, and the pickling time is 35 s; Cold rolling process: through 4 passes of rolling, the thickness of the steel plate is gradually rolled to 0.39 mm, and the cold rolling reduction is 87%; Low temperature annealing process: the steel coil after rolling is heated to 430℃ at a speed of 90℃ / h, kept for 10 hours, furnace cooling to 385℃, air cooling to 340℃ at a speed of 41℃ / h, then furnace cooling to 255℃, finally starting water cooling at a speed of 11℃ / h until cooling to 80℃, and discharged.
[0034] Leveling process: the steel coil after low temperature annealing is leveled by 2 passes, the rolling force of the first pass is controlled at 400kN, and the second pass is 500kN.
[0035] Comparative Example 6: the conventional method described in Comparative Example 1 is used to produce a hard rolled cold-rolled plate with a thickness of 0.39mm.
[0036] Table 6: comparison of the properties of the products produced in Example 6 and Comparative Example 6
[0037] The hard rolled cold-rolled plate obtained in this example is used to produce high-end automotive brake pad products on the market, meeting the requirements of high hardness and high processability, 180° bending frequency ≥5 times, and the qualified product rate can reach 99.9%; the hard rolled cold-rolled plate produced in Comparative Example 6 can only reach a qualified product rate of 95.2%.
Claims
1. A method for producing a high- processability hard rolled cold-rolled sheet, characterized in that, The process comprises hot-rolled steel coil pickling, cold rolling, low-temperature annealing and flattening processes; In the low-temperature annealing process, the steel coil is heated to 430-500 DEG C after cold rolling, and kept for 10-15 hours; then cooled to 380-420 DEG C in the furnace, and then air-cooled to 340-360 DEG C at a speed of 40-50 DEG C / h, and then cooled to 240-260 DEG C in the furnace, and finally water-cooled at a speed of 10-15 DEG C / h.
2. The method of producing high processable hard rolled cold rolled sheet as claimed in claim 1 wherein: In the low-temperature annealing process, the steel coil is heated to 430-500 DEG C at a speed of 90-110 DEG C / h after cold rolling.
3. The method of producing high processable quench hardening cold rolled sheet as claimed in claim 2 wherein: In the low-temperature annealing process, the steel coil is discharged after water-cooled to 70-90 DEG C.
4. The method of producing high processable quench hardening cold rolled sheet as claimed in claim 3 wherein: In the flattening process, two passes of flattening are adopted, the rolling force of the first pass is controlled to be 400-900 kN, and the rolling force of the second pass is controlled to be 300-500 kN.
5. The method of producing a high- processability quench-hardened cold-rolled sheet according to any one of claims 1 to 4, characterized in that: The chemical composition of the hot-rolled steel coil, in terms of mass percentage, is: C: 0.02-0.09%, Si≤0.03%, Mn: 0.15-0.35%, P≤0.02%, S≤0.015%, Als≤0.2%, and the balance being Fe and inevitable impurities.