Process method for reducing hot-rolled hardness and lateral bending of 52CrMoV4 flat steel
Through fine temperature control and cooling methods, the hot-rolled hardness of 52CrMoV4 flat steel is solved by using continuous casting billet heating, high-pressure water descaling, rough rolling, cooling, continuous rolling, fine rolling, water-through cooling and cold bed cooling processes. As for the problem of difficult to control the bending degree, low-cost and high-efficiency production has been achieved, and it meets the national energy-saving and carbon reduction requirements.
Patent Information
- Application Number
- CN202411375742.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-02-14
AI Technical Summary
The prior art is difficult to effectively control the hot-rolled hardness and bending of 52CrMoV4 flat steel, resulting in high production costs, low production efficiency, and does not meet the national energy-saving and carbon reduction requirements.
A process method is adopted, including continuous casting billet heating, high-pressure water descaling, rough rolling, cooling, continuous rolling, fine rolling, water-through cooling and cold bed cooling. Through fine temperature control and cooling methods, 52CrMoV4 flat is reduced The hardness and bending of steel are hot-rolled.
It has achieved effective control of the hardness and bending degree of the hot-rolled 52CrMoV4 flat steel, meeting the user's standards and requirements, reducing production costs, improving production efficiency, and meeting the national energy-saving and carbon reduction requirements.
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Figure CN119426355A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of special steel production and processing in the metallurgical industry, relates to a rolling process, and in particular to a method for reducing the hot-rolled hardness and side bending of 52CrMoV4 flat steel. Background Art
[0002] With the introduction of the "GB7258-2017 Technical Conditions for Motor Vehicle Operation Safety" and the development of China's commercial vehicle chassis suspension system, more and more commercial vehicles and trailers are beginning to be equipped with air suspension systems, and 52CrMoV4 flat steel is the main material for air suspension guide arms. 52CrMoV4 flat steel has high hardenability and excellent mechanical properties, but in the production process, due to its high hardenability, it is difficult to control its hot-rolled structure, hardness and curvature. Auto parts processing companies need to anneal and straighten before use. This situation not only increases production costs, but also does not meet the national "carbon reduction" requirements in the industrial production process.
[0003] At present, the hardness and curvature of 52CrMoV4 flat steel produced in China cannot meet the requirements of direct use by parts processing enterprises. Some steel enterprises use slow cooling and subsequent annealing processes to ensure the hot-rolled hardness of 52CrMoV4, which not only increases production costs and reduces production efficiency, but also causes the curvature to exceed the standard. Therefore, there is an urgent need for an environmentally friendly, low-cost, high-efficiency, and simple-to-operate method to reduce the hot-rolled hardness and side bending of 52CrMoV4 flat steel. Summary of the invention
[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a process method for reducing the hot-rolled hardness and side bending of 52CrMoV4 flat steel. The process method has the advantages of simple process route, low production cost, strong operability, and can fully meet the user's requirements for the hot-rolled hardness and bending of 52CrMoV4 flat steel.
[0005] To achieve the above object, the present invention provides the following technical scheme, a method for reducing the hot-rolled hardness and lateral bending of 52CrMoV4 flat steel, using 52CrMoV4 continuous casting billet as raw material, the method sequentially comprises the following steps: gas furnace heating, high-pressure water descaling, rough rolling, high-pressure water descaling, cooling after rough rolling, continuous rolling, flat steel finishing rolling, water cooling, cooling on a cooling bed, and finally obtaining a finished flat steel. Cooling, finally obtaining a finished flat steel.
[0006] Preferably, in the gas furnace heating process, the continuous casting billet is heated, and the gas furnace heating is divided into five sections, namely, a preheating section, a heating section I, a heating section II, a heating section III and a soaking section; the temperature of the preheating section is ≤700°C; the heating temperature of the heating section I is 750-850°C; the heating temperature of the heating section II is 900-1000°C, the heating temperature of the heating section III is 1000-1050°C, and the temperature of the soaking section is 1030-1070°C; the total heating time in the gas furnace heating process is 170-270 min, and the soaking time of the soaking section is 40-90 min.
[0007] Preferably, in the rough rolling process, the starting rolling temperature is 950-1000° C., and the number of rough rolling passes is 4-5.
[0008] Preferably, in the water cooling process, the semi-finished flat steel product after finish rolling is water cooled to 750-800°C; the water cooling rate of the water cooling is 50-100°C / s, and the water pressure is 0.4-0.8MPa.
[0009] Preferably, the specific method of the cooling process of the cooling bed is: first, the flat steel obtained after the flat steel finish rolling is slowly cooled to below 500°C in the cooling bed insulation cover, and then the cooling bed is air-cooled out of the insulation cover, and the temperature out of the cooling bed insulation cover is ≤350°C; the opening angle of the cooling bed insulation cover is 10°-60°, the interval time of the flat steel on the cooling bed is 110-140s, and the cooling rate of the slow cooling is ≤14°C / min.
[0010] Preferably, in the flat steel finish rolling process, the starting rolling temperature is 800-850°C.
[0011] Preferably, the continuous rolling process includes 6 high-rigidity rolling mills, the temperature entering the continuous rolling mill is 900-950°C, and the temperature exiting the continuous rolling mill is 850-900°C.
[0012] Preferably, the hot-rolled hardness value of the 52CrMoV4 flat steel is in the range of 280-340 HBW, the curvature is ≤3 mm / m, and the thickness of the finished flat steel is below 60 mm.
[0013] The production process of the present invention also has the following advantages: the hot-rolled hardness value and curvature control of the 52CrMoV4 flat steel produced by the above process fully meet the standards and user requirements; the on-site operation is simple, and online automatic control is easy to realize, reducing the labor intensity of workers; the subsequent heat treatment process (annealing process) is reduced, saving production costs, shortening the production cycle, improving the market competitiveness of steel, and meeting the national requirements for energy conservation and carbon reduction. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1It is the metallographic structure of 52CrMoV4 flat steel produced by other processes.
[0015] Figure 2 This is a metallographic structure photograph of the 52CrMoV4 flat steel rolled in Example 1 of the present invention.
[0016] Figure 3 This is a metallographic structure photograph of the 52CrMoV4 flat steel rolled in Example 2 of the present invention.
[0017] Figure 4 This is a metallographic structure photograph of the 52CrMoV4 flat steel rolled in Example 3 of the present invention. DETAILED DESCRIPTION
[0018] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0019] Example 1
[0020] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and examples. This embodiment provides a method for reducing the hot-rolled hardness and side bending of 52CrMoV4 flat steel, and the specific implementation steps are as follows:
[0021] 1) Heating of continuous casting billet: The continuous casting billet is heated in a four-stage walking beam gas furnace, and the heating temperatures are: 686°C in the preheating stage, 786-800°C in the heating stage I, 976-991°C in the heating stage II, 1025-1048°C in the heating stage III, and 1053-1065°C in the soaking stage. The total heating time is 190-230 minutes, and the soaking time in the soaking stage is 53-64 minutes.
[0022] 2) High-pressure water descaling of continuous casting billets: After the continuous casting billets are heated by a gas furnace, high-pressure water is used to descaling the iron oxide produced by heating. The high-pressure water descaling pressure is 24MPa.
[0023] 3) Rough rolling of continuous casting billets: The descaled continuous casting billets are sent to 5 high-rigidity rough rolling mills for rough rolling to obtain rough rolled billets. The starting rolling temperature is 967°C and the rough rolling outlet temperature is 899°C.
[0024] 4) High-pressure water descaling of rough-rolled billets: Use high-pressure water descaling to remove the secondary iron oxide scale produced in the rough rolling process of the rough-rolled billets. The high-pressure water descaling pressure is 21MPa.
[0025] 5) Cooling on the de-heading roller: The rough rolled billet is naturally cooled in the de-heading roller area after being descaled by high-pressure water.
[0026] 6) Continuous rolling: The obtained rough rolled billet is sent to a continuous rolling mill for continuous rolling. The continuous rolling mill includes 6 high-rigidity rolling mills. The temperature entering the continuous rolling mill is 920°C, and the temperature leaving the continuous rolling mill is 875°C.
[0027] 7) Finish rolling: The 70mm×120mm rolled material obtained after continuous rolling is subjected to three passes of finish rolling to obtain 56mm×100mm flat steel. The start temperature of the finish rolling is 850℃ and the outlet temperature is 810℃.
[0028] 8) Water piercing after finishing rolling: 56mm×100mm flat steel is water-cooled to 800℃, the water cooling rate is 50℃ / s, and the water pressure is 0.4MPa.
[0029] 9) Cooling on cooling bed: The flat steel obtained in step 8 is cooled to 350°C at a cooling rate of 14°C / min in the insulation cover of the cooling bed. The insulation cover is opened at an angle of 15°. Each steel is placed on the cooling bed for 120 seconds, and then removed from the insulation cover for air cooling on the cooling bed to finally obtain the finished flat steel.
[0030] The method of this embodiment is used to roll 50 tons of flat steel, the specification of which is 56mm×100mm, and the chemical composition is: 0.54%C, 0.22%Si, 1.01%Mn, 1.15%Cr, 0.17%Mo, 0.12%V, 0.02%Ni, and the rest is balanced Fe and inevitable impurities. The metallographic structure of the flat steel rolled in this embodiment is ferrite+pearlite. The hardness value of the 52CrMoV4 flat steel with a specification of 56mm×100mm is 282-313HBW measured by a Brinell hardness tester; the curvature of the steel off-line is significantly improved after cooling on the cooling bed, and the curvature is improved from the original ≥5mm / m to ≤3mm / m; the steel does not need to be straightened. The comparison of the metallographic structure, hot-rolled hardness and curvature of 52CrMoV4 flat steel with a size of 56mm×100mm before and after using this process is shown in Table 1. The metallographic structure of 52CrMoV4 flat steel with a size of 56mm×100mm produced by other processes is shown in Table Figure 1 The metallographic structure of 52CrMoV4 flat steel with a specification of 56mm×100mm produced by this process is shown in Figure 2 .
[0031] Table 1 Example 1 Comparison of data before and after using this process to produce 56mmX100mm 52CrMoV4 flat steel
[0032] Note: F—ferrite; P—pearlite; B—bainite; M—martensite
[0033] Table 2 Mechanical properties of the products prepared in Example 1
[0034]
[0035] Example 2
[0036] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and examples. This embodiment provides a method for reducing the hot-rolled hardness and side bending of 52CrMoV4 flat steel, and the specific implementation steps are as follows:
[0037] 1) Heating of continuous casting billet: The continuous casting billet is heated in a four-stage walking-beam gas furnace, and the heating temperatures are: 696°C in the preheating stage, 800-850°C in the heating stage I, 991-1000°C in the heating stage II, 1048-1050°C in the heating stage III, and 1065-1070°C in the soaking stage. The total heating time is 230-270 minutes, and the soaking time in the soaking stage is 64-90 minutes.
[0038] 2) High-pressure water descaling of continuous casting billets: After the continuous casting billets are heated by a gas furnace, high-pressure water is used to descaling the iron oxide produced by heating. The high-pressure water descaling pressure is 24MPa.
[0039] 3) Rough rolling of continuous casting billet: The descaled continuous casting billet is sent to 5 high-rigidity rough rolling mills for rough rolling to obtain rough rolled billet. The starting rolling temperature is 1000°C and the rough rolling outlet temperature is 932°C.
[0040] 4) High-pressure water descaling of rough-rolled billets: Use high-pressure water descaling to remove the secondary iron oxide scale produced in the rough rolling process of the rough-rolled billets. The high-pressure water descaling pressure is 21MPa.
[0041] 5) Cooling on the de-heading roller: The rough rolled billet is naturally cooled in the de-heading roller area after being descaled by high-pressure water.
[0042] 6) Continuous rolling: The obtained rough rolled billet is sent to a continuous rolling mill for continuous rolling. The continuous rolling mill includes 6 high-rigidity rolling mills. The temperature entering the continuous rolling mill is 900°C, and the temperature leaving the continuous rolling mill is 850°C.
[0043] 7) Finish rolling: The 70mm×120mm rolled material obtained after continuous rolling is subjected to three passes of finish rolling to obtain 56mm×100mm flat steel. The start temperature of the finish rolling is 880℃ and the outlet temperature is 840℃.
[0044] 8) Water piercing after finishing rolling: 56mm×100mm flat steel is water-cooled to 780℃, the water cooling rate is 80℃ / s, and the water pressure is 0.6MPa.
[0045] 9) Cooling on cooling bed: The flat steel obtained in step 8 is cooled to 330°C at a cooling rate of 12°C / min in the insulation cover of the cooling bed. The insulation cover is opened at an angle of 10°. Each steel is placed on the cooling bed for 140 seconds, and then removed from the insulation cover for air cooling on the cooling bed to finally obtain the finished flat steel.
[0046] The method of this embodiment is used to roll 50 tons of flat steel, the specification of which is 56mm×100mm, and the chemical composition is: 0.55%C, 0.21%Si, 1.00%Mn, 1.16%Cr, 0.16%Mo, 0.13%V, 0.02%Ni, and the rest is balanced Fe and inevitable impurities. The metallographic structure of the flat steel rolled in this embodiment is ferrite+pearlite. The hardness value of the 52CrMoV4 flat steel with a specification of 56mm×100mm is 280-313HBW measured by a Brinell hardness tester; the curvature of the steel off-line is significantly improved after cooling on the cooling bed, and the curvature is improved from the original ≥5mm / m to ≤3mm / m; the steel does not need to be straightened. The comparison of the metallographic structure, hot-rolled hardness and curvature of 52CrMoV4 flat steel with a size of 56mm×100mm before and after using this process is shown in Table 3. The metallographic structure of 52CrMoV4 flat steel with a size of 56mm×100mm produced by other processes is shown in Table Figure 1 The metallographic structure of 52CrMoV4 flat steel with a specification of 56mm×100mm produced by this process is shown in Figure 3 .
[0047] Table 3 Comparison of data before and after using this process to produce 56mmX100mm 52CrMoV4 flat steel in Example 2
[0048] Note: F—ferrite; P—pearlite; B—bainite; M—martensite
[0049] Table 4 Mechanical properties of the products prepared in Example 2
[0050]
[0051] Example 3
[0052] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and examples. This embodiment provides a method for reducing the hot-rolled hardness and side bending of 52CrMoV4 flat steel, and the specific implementation steps are as follows:
[0053] 1) Heating of continuous casting billet: The continuous casting billet is heated in a four-stage walking-beam gas furnace, and the heating temperatures are: 685°C in the preheating stage, 750-800°C in the heating stage I, 900-991°C in the heating stage II, 1000-1048°C in the heating stage III, and 1030-1065°C in the soaking stage. The total heating time is 170-230 minutes, and the soaking time in the soaking stage is 40-64 minutes.
[0054] 2) High-pressure water descaling of continuous casting billets: After the continuous casting billets are heated by a gas furnace, high-pressure water is used to descaling the iron oxide produced by heating. The high-pressure water descaling pressure is 24MPa.
[0055] 3) Rough rolling of continuous casting billets: The descaled continuous casting billets are sent to 5 high-rigidity rough rolling mills for rough rolling to obtain rough rolled billets. The starting rolling temperature is 950°C and the rough rolling outlet temperature is 882°C.
[0056] 4) High-pressure water descaling of rough-rolled billets: Use high-pressure water descaling to remove the secondary iron oxide scale produced in the rough rolling process of the rough-rolled billets. The high-pressure water descaling pressure is 21MPa.
[0057] 5) Cooling on the de-heading roller: The rough rolled billet is naturally cooled in the de-heading roller area after being descaled by high-pressure water.
[0058] 6) Continuous rolling: The obtained rough rolled billet is sent to a continuous rolling mill for continuous rolling. The continuous rolling mill includes 6 high-rigidity rolling mills. The temperature entering the continuous rolling mill is 950°C, and the temperature leaving the continuous rolling mill is 900°C.
[0059] 7) Finishing rolling: The 70mm×120mm rolled material obtained after continuous rolling is subjected to three passes of finishing rolling to obtain 56mm×100mm flat steel. The finishing rolling start temperature is 800℃ and the outlet temperature is 760℃.
[0060] 8) Water piercing after finishing rolling: 56mm×100mm flat steel is water-cooled to 750℃, the water cooling rate is 100℃ / s, and the water pressure is 0.8MPa.
[0061] 9) Cooling on cooling bed: The flat steel obtained in step 8 is cooled to 340°C at a cooling rate of 13°C / min in the insulation cover of the cooling bed. The insulation cover is opened at an angle of 60°. Each steel is placed on the cooling bed for 110 seconds, and then removed from the insulation cover for air cooling on the cooling bed to finally obtain the finished flat steel.
[0062] The method of this embodiment is used to roll 50 tons of flat steel, the specification of which is 56mm×100mm, and the chemical composition is: 0.53%C, 0.23%Si, 1.01%Mn, 1.15%Cr, 0.17%Mo, 0.14%V, 0.01%Ni, and the rest is balanced Fe and inevitable impurities. The metallographic structure of the flat steel rolled in this embodiment is ferrite+pearlite. The hardness value of the 52CrMoV4 flat steel with a specification of 56mm×100mm is 313-340HBW measured by a Brinell hardness tester; the curvature of the steel off-line is significantly improved after cooling on the cooling bed, and the curvature is improved from the original ≥5mm / m to ≤3mm / m; the steel does not need to be straightened. The comparison of the metallographic structure, hot-rolled hardness and curvature of 52CrMoV4 flat steel with a size of 56mm×100mm before and after using this process is shown in Table 5. The metallographic structure of 52CrMoV4 flat steel with a size of 56mm×100mm produced by other processes is shown in Table 5. Figure 1 The metallographic structure of 52CrMoV4 flat steel with a specification of 56mm×100mm produced by this process is shown in Figure 4 .
[0063] Table 5 Comparison of data before and after using this process to produce 56mmX100mm 52CrMoV4 flat steel in Example 3
[0064] Note: F—ferrite; P—pearlite; B—bainite; M—martensite
[0065] Table 6 Mechanical properties of the products prepared in Example 3
[0066]
Claims
1. A method for reducing the hot-rolled hardness and side bending of 52CrMoV4 flat steel, characterized in that The process method uses 52CrMoV4 continuous casting billet as raw material, and comprises the following steps in sequence: gas furnace heating, high-pressure water descaling, rough rolling, high-pressure water descaling, cooling after rough rolling, continuous rolling, flat steel finish rolling, water cooling, cooling on a cooling bed, and finally obtaining finished flat steel.
2. The process according to claim 1, characterized in that: In the gas furnace heating process, the continuous casting billet is heated, and the gas furnace heating is divided into five sections, namely, preheating section, heating section I, heating section II, heating section III and soaking section; the temperature of the preheating section is ≤700°C; the heating temperature of the heating section I is 750-850°C; the heating temperature of the heating section II is 900-1000°C, the heating temperature of the heating section III is 1000-1050°C, and the temperature of the soaking section is 1030-1070°C; the total heating time in the gas furnace heating process is 170-270 min, and the soaking time of the soaking section is 40-90 min.
3. The process according to claim 1, characterized in that: In the rough rolling process, the starting rolling temperature is 950-1000° C., and the rough rolling passes are 4-5 times.
4. The process according to claim 1, characterized in that: In the water cooling process, the semi-finished flat steel product after finish rolling is water cooled to 750-800°C; the water cooling rate of the water cooling is 50-100°C / s, and the water pressure is 0.4-0.8MPa.
5. The process according to claim 1, characterized in that: The specific method of the cooling process of the cooling bed is: the flat steel obtained after the flat steel finish rolling is slowly cooled to below 500°C in the cooling bed insulation cover, and then taken out of the insulation cover for air cooling of the cooling bed, and the temperature out of the cooling bed insulation cover is ≤350°C; the opening angle of the cooling bed insulation cover is 10°-60°, the interval time of the flat steel on the cooling bed is 110-140s, and the cooling rate of the slow cooling is ≤14°C / min.
6. The process according to claim 1, characterized in that: In the flat steel finish rolling process, the starting rolling temperature is 800-850°C.
7. The process according to claim 1, characterized in that: The continuous rolling process includes 6 high-rigidity rolling mills, the temperature entering the continuous rolling mill is 900-950°C, and the temperature leaving the continuous rolling mill is 850-900°C.
8. The process according to any one of claims 1 to 7, characterized in that: The hot-rolled hardness value of the 52CrMoV4 flat steel is in the range of 280-340 HBW, the curvature is ≤3 mm / m, and the thickness of the finished flat steel is below 60 mm.