CN115466828B - Production method for improving bending degree of low-alloy high-strength steel - Google Patents
Production method for improving bending degree of low-alloy high-strength steel Download PDFInfo
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Abstract
The invention discloses a production method for improving bending degree of low-alloy high-strength steel, and belongs to the technical field of metallurgy. The production method comprises the following steps: converter smelting, continuous casting, rolling, normalizing, straightening and stress relief annealing; normalizing process: the temperature rising speed is less than or equal to 100 ℃/h, and the heat preservation temperature is as follows: 890-920 ℃, straightening process: and (5) straightening through a combination of a pressure straightener and a multi-roller straightener after normalizing. The invention realizes the performance of the low-alloy high-strength structural steel by reasonably controlling chemical components and production process, ensures that the bending degree of the final bar is less than or equal to 2.5mm/m, and solves the problem of repeated straightening stress-relieving annealing process.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a production method for improving bending degree of low-alloy high-strength steel.
Background
With the development of scientific technology and metallurgical industry, the metal consumption is reduced to the maximum extent, the manufacturing cost of hot forging and cutting processing industries is reduced, and higher requirements are made on the appearance and the size of long products. The downstream user puts new requirements on the bar curvature: the curvature is required to be improved from the original curvature of less than or equal to 4mm/m to the curvature of less than or equal to 2mm/m. The low-alloy high-strength structural steel bars delivered in the normalizing state cannot meet the requirement of 0-2.5mm/m in bending degree and must be straightened.
The stress of the straightened bar, which remains in the metal after the external force is removed, is called residual stress or internal stress. Residual stress is due to non-uniform deformation of the metal and non-uniform volume change. Residual stresses can be classified into macroscopic internal stresses (first type of residual stress), grain boundary internal stresses (second type of residual stress), and lattice distortion internal stresses (third type of residual stress) according to the range of the internal stress.
Residual stresses can lead to work distortion, cracking and partial dimensional or shape changes, shortening the useful life of the workpiece. In order to eliminate the residual stress, a heat treatment method and a mechanical treatment method are generally used. The metallic material that is allowed to anneal may be relieved of residual stress by annealing.
The annealing process is to heat the steel part to a certain temperature, keep the temperature for a certain time, then slowly cool the steel part to room temperature, eliminate the internal stress in the steel and prevent the deformation and cracking of the part after processing. In the stress relief annealing process, the heat treatment rolled piece is deformed due to temperature difference and phase change, the material after normalizing is not straightened or the bending degree is not precisely controlled through straightening, the bar bending degree after the stress relief annealing can not meet the requirement of 0-2.5mm/m, and the material needs to be straightened again for secondary stress relief annealing, so that infinite repeated heat treatment and straightening treatment are formed. At present, with reference to domestic data, no solution to the above problems is found.
Disclosure of Invention
The invention provides a production method for improving the bending degree of low-alloy high-strength steel, which solves the problems that the low-alloy high-strength structural steel is deformed due to bending after normalizing, needs to be subjected to stress relief annealing after straightening, generates secondary bending, cannot meet turning requirements and needs to be subjected to repeated stress relief annealing.
In order to solve the technical problems, the invention adopts the following technical scheme: a method of producing a low alloy, high strength steel having improved bending, the method comprising: converter smelting, continuous casting, rolling, normalizing, straightening and stress relief annealing; the normalizing process comprises the following steps: the temperature rising speed is less than or equal to 100 ℃/h, and the heat preservation temperature is as follows: 890-920 ℃, and the heat preservation time is as follows: and (2) more than or equal to phi/100 x 1 hour, wherein phi is the diameter of the low-alloy high-strength steel bar, and the unit is: millimeter; the straightening process comprises the following steps: after normalizing, the steel is straightened by a combination of a pressure straightener and a multi-roller straightener, and the maximum straightening force of the pressure straightener is as follows: less than or equal to 15MN, straightening precision: less than or equal to 3 per mill mm/m; maximum straightening force of multi-roller straightener: less than or equal to 7.5MN, the curvature of the incoming material less than or equal to 10mm/m, and the straightening precision less than or equal to 1mm/m; the curvature of the incoming material is less than or equal to 20mm/m, the straightening precision is less than or equal to 1.5mm/m, the curvature of the straightened bar is less than or equal to 2mm/m, and the curvature is less than or equal to 2.5mm/m through stress relief annealing treatment.
The continuous casting process comprises the following steps: continuous casting superheat degree is 15-25 ℃, and the crystallizer is subjected to electromagnetic stirring: 100A-200A current, 2.0-8.0 HZ frequency, 100A-200A current stirring at the end of the crystallizer, 2.0-8.0 HZ frequency.
The normalizing process of the invention has the following performance parameters of the low-alloy high-strength steel after normalizing: the tensile strength is greater than or equal to 530Mpa, the yield strength is greater than or equal to 350Mpa, the elongation is greater than or equal to 35%, the area shrinkage is greater than or equal to 76%, and the longitudinal impact value at minus 40 ℃ is greater than or equal to 180J.
The rolling process comprises the following steps: the initial rolling temperature of the continuous rolling mill is controlled to be less than or equal to 950 ℃, the final rolling temperature is controlled to be less than or equal to 880 ℃, the high-temperature collecting and pit entering slow cooling of the bar is carried out, the pit entering temperature is more than or equal to 700 ℃, the uncovering temperature is controlled to be less than or equal to 200 ℃, and the pit exiting temperature is controlled to be less than or equal to 150 ℃.
The annealing process comprises the following steps: the temperature rising speed is less than or equal to 100 ℃/h, and the heat preservation temperature is as follows: heat preservation time at 540-560 ℃): and (2) not less than phi is 1 min, wherein phi is the diameter of the low-alloy high-strength steel bar, and the unit is: millimeter.
The low-alloy high-strength structural steel comprises the following chemical components in percentage by mass: c:0.15-0.17%, si 0.20-0.26%, mn:1.32-1.40%, P is less than or equal to 0.015%, S is less than or equal to 0.003%, ti is less than or equal to 0.005%, V:0.03-0.05%, nb:0.02-0.04%, al:0.025-0.040%, cr:0.06-0.10% and the others are unavoidable residual elements.
The annealing process comprises the following steps: the interval between each bar is greater than 40mm, and every layer is separated with the parting bead, and the parting bead aligns with lower floor's sizing block, and bar both ends are not allowed to surpass both ends sizing block 200mm.
The normalizing process comprises the following steps: the sizing blocks are uniformly placed before the furnace is charged, so that bar bending is reduced, and meanwhile, the sizing blocks are not allowed to block the burner. The interval between each bar is greater than 40mm, and every layer is separated with the parting bead, and the parting bead aligns with lower floor's sizing block, and bar both ends are not allowed to surpass both ends sizing block 200mm.
The specification of the low-alloy high-strength steel bar material is as follows: the diameter phi is 80-300mm, and the length range of the specified size is 4000-8000mm.
The design principle of the invention is as follows: in the component design of the invention, V, nb and Al elements are added, the structure grains are refined, and the mechanical property value is improved. The component Ti is controlled to be less than or equal to 0.005 percent according to the target value, which is beneficial to improving the low-temperature impact value. Continuous casting process: and proper technological parameters of electromagnetic stirring of the crystallizer and stirring of the tail end of the crystallizer are selected, so that component segregation is reduced, component uniformity is improved, and the mechanical properties after normalizing are ensured to meet the requirements. In order to avoid the generation of white spot defects of steel, hydrogen in the steel is fully separated out, a pit-entering slow cooling process is adopted, and a common high-temperature bar with the temperature of 20-100 t is used for pit heating, so that the minimum difference between the temperature of the slow cooling pit and the temperature of the pit-entering bar is ensured. Normalizing process: the bars are aligned and uniformly placed in the furnace, the sizing blocks are uniformly placed, the burner is not blocked, the heating temperature consistency of the steel is ensured, the reasonable heating speed, the heat preservation temperature and the heat preservation time are ensured, and the performance after normalizing is exerted to the highest. Annealing: the bars are aligned and uniformly placed in the furnace, the sizing blocks are uniformly placed, the burner is not blocked, the heating temperature consistency of the steel is ensured, the reasonable heating speed, the heat preservation temperature and the cooling time are ensured, and the straightening stress generated by the straightened bars is completely released through annealing treatment.
The Q355NE steel disclosed by the invention has the standard tensile strength of GB/T1591-2018: 450-600Mpa, yield strength is more than or equal to 275Mpa; the area reduction rate is more than or equal to 21 percent; the longitudinal impact value at the temperature of minus 40 ℃ is more than or equal to 31J. The mechanical property value after normalizing is higher than the property value of the national standard GB/T1591-2018 with the same steel grade, thereby meeting the use requirement of users.
The beneficial effects of adopting above-mentioned technical scheme to produce lie in: 1. the invention realizes the low alloy high strength structural steel with tensile strength more than or equal to 530Mpa and yield strength more than or equal to 350Mpa through reasonable control of chemical components and production process; the elongation rate is more than or equal to 35%; the area reduction rate is more than or equal to 76 percent; the longitudinal impact value at the temperature of minus 40 ℃ is more than or equal to 180J. 2. The invention ensures that the bending degree of the final bar is less than or equal to 2.5mm/m through the normalizing and composite straightening process, thereby meeting the requirements of customers.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Example 1
A production method for improving the bending degree of low-alloy high-strength steel Q355NE comprises the working procedures of converter smelting, continuous casting, rolling, normalizing, straightening and stress relief annealing. The chemical components and mass percentages of the low-alloy high-strength steel are shown in table 1, and the specific control parameters are as follows:
continuous casting process: continuous casting superheat degree is 25 ℃, and the crystallizer is subjected to electromagnetic stirring: current 200A, frequency 2.0 HZ, crystallizer tip stirring current 100A, frequency 8.0 HZ.
And (3) rolling: controlling the initial rolling temperature of the continuous rolling mill to 930 ℃, the final rolling temperature to 860 ℃, collecting the bars at high temperature, slowly cooling the bars into pits, entering the pits to 700 ℃, opening the cover to 195 ℃ and discharging the bars from the pits to 150 ℃.
Normalizing process: heating rate 50 ℃/h, and heat preservation temperature: 920 ℃, heat preservation time: the performance parameters of the low-alloy high-strength steel after normalizing are shown in Table 2, and the bending degree and bar specification are shown in Table 3 after normalizing for 1.5 hours.
Normalizing process: the sizing blocks are uniformly placed before the furnace is charged, so that bar bending is reduced, and meanwhile, the sizing blocks are not allowed to block the burner. The interval between each bar is greater than 40mm, and every layer is separated with the parting bead, and the parting bead aligns with lower floor's sizing block, and bar both ends are not allowed to surpass both ends sizing block 200mm.
Straightening: after normalizing, the steel is straightened by a combination of a pressure straightener and a multi-roller straightener, and the maximum straightening force of the pressure straightener is as follows: 15MN, straightening precision: 3%mm/m; maximum straightening force of multi-roller straightener: 7.5MN, the curvature of the incoming material is 10mm/m, the straightening precision is 1mm/m, and the curvature after straightening is shown in Table 3.
Annealing: the temperature rising speed is 60 ℃/h. Heat preservation temperature: 540 ℃, and the heat preservation time is as follows: 100 minutes, calculated from the bar diameter. The spacing between each bar is greater than 40mm, each layer is separated by a parting bead, the parting bead is aligned with the sizing block at the lower layer, the two ends of the bar are not allowed to exceed the sizing blocks at the two ends by 200mm, and the bending degree after annealing is shown in Table 3.
Example 2
A production method for improving the bending degree of low-alloy high-strength steel Q355NE comprises the working procedures of converter smelting, continuous casting, rolling, normalizing, straightening and stress relief annealing. The chemical components and mass percentages of the low-alloy high-strength steel are shown in table 1, and the specific control parameters are as follows:
continuous casting process: continuous casting superheat degree is 15 ℃, and the crystallizer is subjected to electromagnetic stirring: current 120A, frequency 6.0 HZ, crystallizer tip stirring current 180A, frequency 4.0 HZ.
And (3) rolling: controlling the initial rolling temperature of the continuous rolling mill to 950 ℃, the final rolling temperature to 870 ℃, collecting the bars at high temperature, slowly cooling the bars into pits, entering the pits to 790 ℃, opening the cover to 150 ℃, and discharging the bars from the pits to 115 ℃.
Normalizing process: heating rate is 65 ℃/h, and heat preservation temperature is as follows: 890 ℃, the heat preservation time is as follows: the performance parameters of the low-alloy high-strength steel after normalizing are shown in Table 2, and the bending degree and bar specification are shown in Table 3.
Normalizing process: the sizing blocks are uniformly placed before the furnace is charged, so that bar bending is reduced, and meanwhile, the sizing blocks are not allowed to block the burner. The interval between each bar is greater than 40mm, and every layer is separated with the parting bead, and the parting bead aligns with lower floor's sizing block, and bar both ends are not allowed to surpass both ends sizing block 200mm.
Straightening: after normalizing, the steel is straightened by a combination of a pressure straightener and a multi-roller straightener, and the maximum straightening force of the pressure straightener is as follows: 12MN, straightening precision: 2%mm/m; maximum straightening force of multi-roller straightener: 7MN, the curvature of the incoming material is 5mm/m, the straightening precision is 1mm/m, and the curvature after straightening is shown in Table 3.
Annealing: the temperature rising speed is 55 ℃/h. Heat preservation temperature: 560 ℃ and heat preservation time: 250 minutes, calculated from the diameter of the rod. The spacing between each bar is greater than 40mm, each layer is separated by a parting bead, the parting bead is aligned with the sizing block at the lower layer, the two ends of the bar are not allowed to exceed the sizing blocks at the two ends by 200mm, and the bending degree after annealing is shown in Table 3.
Example 3
A production method for improving the bending degree of low-alloy high-strength steel Q355NE comprises the working procedures of converter smelting, continuous casting, rolling, normalizing, straightening and stress relief annealing. The chemical components and mass percentages of the low-alloy high-strength steel are shown in table 1, and the specific control parameters are as follows:
continuous casting process: continuously casting the super-heated temperature of 20 ℃, and electromagnetically stirring by a crystallizer: current 150A, frequency 4.0 HZ, crystallizer tip stirring current 150A, frequency 6.0 HZ.
And (3) rolling: the initial rolling temperature of the continuous rolling mill is controlled to 940 ℃, the final rolling temperature is controlled to 880 ℃, the bars are collected at high temperature and slowly cooled in pits, the pit entering temperature is 750 ℃, the cover opening temperature is controlled to 175 ℃, and the pit exiting temperature is controlled to 130 ℃.
Normalizing process: heating rate 70 ℃/h, and heat preservation temperature: 920 ℃, heat preservation time: the performance parameters of the low-alloy high-strength steel after normalizing are shown in Table 2, and the bending degree and bar specification are shown in Table 3.
Normalizing process: the sizing blocks are uniformly placed before the furnace is charged, so that bar bending is reduced, and meanwhile, the sizing blocks are not allowed to block the burner. The interval between each bar is greater than 40mm, and every layer is separated with the parting bead, and the parting bead aligns with lower floor's sizing block, and bar both ends are not allowed to surpass both ends sizing block 200mm.
Straightening: after normalizing, the steel is straightened by a combination of a pressure straightener and a multi-roller straightener, and the maximum straightening force of the pressure straightener is as follows: 15MN, straightening precision: 3%mm/m; maximum straightening force of multi-roller straightener: 7.5MN, the curvature of the incoming material is 8mm/m, the straightening precision is 0.5mm/m, and the curvature after straightening is shown in Table 3.
Annealing: the temperature rising speed is 85 ℃/h. Heat preservation temperature: 545 ℃, and the heat preservation time is as follows: 150 minutes, calculated from the diameter of the rod. The spacing between each bar is greater than 40mm, each layer is separated by a parting bead, the parting bead is aligned with the sizing block at the lower layer, the two ends of the bar are not allowed to exceed the sizing blocks at the two ends by 200mm, and the bending degree after annealing is shown in Table 3.
Example 4
A production method for improving the bending degree of low-alloy high-strength steel Q355NE comprises the working procedures of converter smelting, continuous casting, rolling, normalizing, straightening and stress relief annealing. The chemical components and mass percentages of the low-alloy high-strength steel are shown in table 1, and the specific control parameters are as follows:
continuous casting process: continuously casting the super-heated temperature of 22 ℃, and electromagnetically stirring by a crystallizer: current 100A, frequency 8.0 HZ, crystallizer tip stirring current 200A, frequency 2.0 HZ.
And (3) rolling: controlling the initial rolling temperature of a continuous rolling mill to 910 ℃, the final rolling temperature to 840 ℃, collecting bars at high temperature, slowly cooling the bars into pits, entering the pits to 740 ℃, uncovering the pits to 180 ℃, and discharging the bars from the pits to 120 ℃.
Normalizing process: heating speed is 95 ℃/h, and heat preservation temperature is as follows: 900 ℃ and the heat preservation time is as follows: the performance parameters of the low-alloy high-strength steel after normalizing are shown in Table 2, and the bending degree and bar specification are shown in Table 3.
Normalizing process: the sizing blocks are uniformly placed before the furnace is charged, so that bar bending is reduced, and meanwhile, the sizing blocks are not allowed to block the burner. The interval between each bar is greater than 40mm, and every layer is separated with the parting bead, and the parting bead aligns with lower floor's sizing block, and bar both ends are not allowed to surpass both ends sizing block 200mm.
Straightening: after normalizing, the steel is straightened by a combination of a pressure straightener and a multi-roller straightener, and the maximum straightening force of the pressure straightener is as follows: 12.5MN, straightening precision: 2%mm/m; maximum straightening force of multi-roller straightener: 6.5MN, the curvature of the incoming material is 12mm/m, the straightening precision is 1.0mm/m, and the curvature after straightening is shown in Table 3.
Annealing: the temperature rising speed is 80 ℃/h. Heat preservation temperature: heat preservation time at 555 ℃): 250 minutes, calculated from the diameter of the rod. The spacing between each bar is greater than 40mm, each layer is separated by a parting bead, the parting bead is aligned with the sizing block at the lower layer, the two ends of the bar are not allowed to exceed the sizing blocks at the two ends by 200mm, and the bending degree after annealing is shown in Table 3.
Example 5
A production method for improving the bending degree of low-alloy high-strength steel Q355NE comprises the working procedures of converter smelting, continuous casting, rolling, normalizing, straightening and stress relief annealing. The chemical components and mass percentages of the low-alloy high-strength steel are shown in table 1, and the specific control parameters are as follows:
continuous casting process: continuously casting the superheat degree to 18 ℃, and electromagnetically stirring by a crystallizer: current 200A, frequency 2.0 HZ, crystallizer tip stirring current 100A, frequency 8.0 HZ.
And (3) rolling: the initial rolling temperature of the continuous rolling mill is controlled to 900 ℃, the final rolling temperature is controlled to 820 ℃, the high-temperature collection of the bars is carried out into pits for slow cooling, the pit entering temperature is 770 ℃, the cover opening temperature is controlled to 200 ℃, and the pit exiting temperature is controlled to 132 ℃.
Normalizing process: heating rate 100 ℃/h, and heat preservation temperature: 895 ℃, heat preservation time: the performance parameters of the low-alloy high-strength steel after normalizing are shown in Table 2, and the bending degree and bar specification are shown in Table 3.
Normalizing process: the sizing blocks are uniformly placed before the furnace is charged, so that bar bending is reduced, and meanwhile, the sizing blocks are not allowed to block the burner. The interval between each bar is greater than 40mm, and every layer is separated with the parting bead, and the parting bead aligns with lower floor's sizing block, and bar both ends are not allowed to surpass both ends sizing block 200mm.
Straightening: after normalizing, the steel is straightened by a combination of a pressure straightener and a multi-roller straightener, and the maximum straightening force of the pressure straightener is as follows: 15MN, straightening precision: 1.5%mm/m; maximum straightening force of multi-roller straightener: 7.5MN, the curvature of the incoming material is 15mm/m, the straightening precision is 1.5mm/m, and the curvature after straightening is shown in Table 3.
Annealing: the temperature rising speed is 100 ℃/h. Heat preservation temperature: 550 ℃, the heat preservation time is as follows: 300 minutes, calculated from the diameter of the rod. The spacing between each bar is greater than 40mm, each layer is separated by a parting bead, the parting bead is aligned with the sizing block at the lower layer, the two ends of the bar are not allowed to exceed the sizing blocks at the two ends by 200mm, and the bending degree after annealing is shown in Table 3.
TABLE 1 EXAMPLES 1-5 Low alloy high strength Steel composition and weight percent (%)
TABLE 2 Low alloy high strength Steel Properties after tempering of examples 1-5
TABLE 3 tortuosity after normalization, after straightening for examples 1-5
The foregoing description is only a preferred embodiment of the present invention, and the scope of the claims is not limited thereto, but the present invention is described in detail with reference to the foregoing embodiments, and those skilled in the art may modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some technical features thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention fall within the scope of the present invention.
Claims (7)
1. A method of producing a low alloy, high strength steel having improved bending, the method comprising: converter smelting, continuous casting, rolling, normalizing, straightening and stress relief annealing;
the low-alloy high-strength steel comprises the following chemical components in percentage by mass: c:0.15-0.17%, si 0.20-0.26%, mn:1.32-1.40%, P is less than or equal to 0.015%, S is less than or equal to 0.003%, ti is less than or equal to 0.005%, V:0.03-0.05%, nb:0.02-0.04%, al:0.025-0.040%, cr:0.06-0.10%, the others are unavoidable residual elements;
the normalizing process comprises the following steps: the temperature rising speed is less than or equal to 100 ℃/h, and the heat preservation temperature is as follows: 890-920 ℃, and the heat preservation time is as follows: and (2) more than or equal to phi/100 x 1 hour, wherein phi is the diameter of the low-alloy high-strength steel bar, and the unit is: millimeter; the performance parameters of the low-alloy high-strength steel after normalizing are as follows: the tensile strength is more than or equal to 530Mpa, the yield strength is more than or equal to 350Mpa, the elongation is more than or equal to 35%, the area shrinkage is more than or equal to 76%, and the longitudinal impact value at minus 40 ℃ is more than or equal to 180J;
the straightening process comprises the following steps: after normalizing, the steel is straightened by a combination of a pressure straightener and a multi-roller straightener, and the maximum straightening force of the pressure straightener is as follows: less than or equal to 15MN, straightening precision: less than or equal to 3 per mill mm/m; maximum straightening force of multi-roller straightener: less than or equal to 7.5MN, the curvature of the incoming material less than or equal to 10mm/m, and the straightening precision less than or equal to 1mm/m; the curvature of the incoming material is less than or equal to 20mm/m, the straightening precision is less than or equal to 1.5mm/m, the curvature of the straightened bar is less than or equal to 2mm/m, and the curvature is less than or equal to 2.5mm/m through stress relief annealing treatment.
2. The method for producing a low-alloy high-strength steel having improved bending as recited in claim 1, wherein said continuous casting step comprises: continuous casting superheat degree is 15-25 ℃, and the crystallizer is subjected to electromagnetic stirring: 100A-200A current, 2.0-8.0 HZ frequency, 100A-200A current stirring at the end of the crystallizer, 2.0-8.0 HZ frequency.
3. The method for producing a low-alloy high-strength steel having improved bending according to claim 1, wherein the rolling step comprises: the initial rolling temperature of the continuous rolling mill is controlled to be less than or equal to 950 ℃, the final rolling temperature is controlled to be less than or equal to 880 ℃, the high-temperature collecting and pit entering slow cooling of the bar is carried out, the pit entering temperature is more than or equal to 700 ℃, the uncovering temperature is controlled to be less than or equal to 200 ℃, and the pit exiting temperature is controlled to be less than or equal to 150 ℃.
4. A method of producing a low alloy, high strength steel having improved bending as claimed in any one of claims 1 to 3, wherein the annealing step: the temperature rising speed is less than or equal to 100 ℃/h, and the heat preservation temperature is as follows: heat preservation time at 540-560 ℃): and (2) not less than phi is 1 min, wherein phi is the diameter of the low-alloy high-strength steel bar, and the unit is: millimeter.
5. A method of producing a low alloy, high strength steel having improved bending as claimed in any one of claims 1 to 3, wherein the annealing step: the interval between each bar is greater than 40mm, and every layer is separated with the parting bead, and the parting bead aligns with lower floor's sizing block, and bar both ends are not allowed to surpass both ends sizing block 200mm.
6. A method of producing a low alloy, high strength steel having improved bending as claimed in any one of claims 1 to 3, wherein the normalizing process comprises: the sizing blocks are uniformly placed before entering the furnace, the bending of the bars is reduced, meanwhile, the sizing blocks do not allow the arrangement of the blocking burner bars, the distance between every two blocking burner bars is larger than 40mm, each layer is separated by a parting bead, the parting bead is aligned with the sizing blocks at the lower layer, and two ends of the bars are not allowed to exceed the sizing blocks at two ends by 200mm.
7. A method of producing a low alloy high strength steel bar according to any one of claims 1 to 3, wherein the low alloy high strength steel bar has the following dimensions: the diameter phi is 80-300mm, and the length range of the specified size is 4000-8000mm.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5672218A (en) * | 1996-06-24 | 1997-09-30 | Slater Steels Corporation | Method of straightening metal bars having extremely low levels of residual stress after straightening operations are completed |
| CN103741068A (en) * | 2014-01-03 | 2014-04-23 | 宝鼎重工股份有限公司 | Special process for freely forging EH36 optimized material steel ingot into plate-shaped bearing seat forged piece |
| CN104805357A (en) * | 2015-05-12 | 2015-07-29 | 首钢总公司 | Low-alloy high-strength steel hot-rolled plate and manufacturing method thereof |
| CN107442670A (en) * | 2017-08-25 | 2017-12-08 | 宝钢特钢韶关有限公司 | A kind of method for rolling square billet aligning |
| CN110918642A (en) * | 2019-10-30 | 2020-03-27 | 邯郸钢铁集团有限责任公司 | Production control method for improving bending degree of 42CrMo bar |
| CN113600611A (en) * | 2021-08-10 | 2021-11-05 | 山东钢铁股份有限公司 | Method for improving hot rolling flatness of bar and controlling bending |
| WO2022127192A1 (en) * | 2020-12-18 | 2022-06-23 | 天津钢铁集团有限公司 | Low-alloy high-strength q420c steel plate and production method therefor |
-
2022
- 2022-08-23 CN CN202211013634.1A patent/CN115466828B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5672218A (en) * | 1996-06-24 | 1997-09-30 | Slater Steels Corporation | Method of straightening metal bars having extremely low levels of residual stress after straightening operations are completed |
| CN103741068A (en) * | 2014-01-03 | 2014-04-23 | 宝鼎重工股份有限公司 | Special process for freely forging EH36 optimized material steel ingot into plate-shaped bearing seat forged piece |
| CN104805357A (en) * | 2015-05-12 | 2015-07-29 | 首钢总公司 | Low-alloy high-strength steel hot-rolled plate and manufacturing method thereof |
| CN107442670A (en) * | 2017-08-25 | 2017-12-08 | 宝钢特钢韶关有限公司 | A kind of method for rolling square billet aligning |
| CN110918642A (en) * | 2019-10-30 | 2020-03-27 | 邯郸钢铁集团有限责任公司 | Production control method for improving bending degree of 42CrMo bar |
| WO2022127192A1 (en) * | 2020-12-18 | 2022-06-23 | 天津钢铁集团有限公司 | Low-alloy high-strength q420c steel plate and production method therefor |
| CN113600611A (en) * | 2021-08-10 | 2021-11-05 | 山东钢铁股份有限公司 | Method for improving hot rolling flatness of bar and controlling bending |
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