CN114769315A - Rolling process for improving surface quality of 20Cr steel bar hot-rolled round steel - Google Patents
Rolling process for improving surface quality of 20Cr steel bar hot-rolled round steel Download PDFInfo
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- CN114769315A CN114769315A CN202210426016.3A CN202210426016A CN114769315A CN 114769315 A CN114769315 A CN 114769315A CN 202210426016 A CN202210426016 A CN 202210426016A CN 114769315 A CN114769315 A CN 114769315A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
- B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/004—Heating the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
- B21B45/08—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing hydraulically
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B2201/00—Special rolling modes
- B21B2201/06—Thermomechanical rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B2261/00—Product parameters
- B21B2261/20—Temperature
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Metal Rolling (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention belongs to the technical field of steel rolling, and particularly relates to a rolling process for improving the surface quality of 20Cr steel bar hot-rolled round steel. The method comprises the following specific steps: smelting, casting into a steel billet, and then carrying out hot rolling at a preheating section of 600-710 ℃; heating for 1 section 940-980 ℃; heating the mixture for 2 sections at the temperature of 1150-1180 ℃; the temperature of the soaking section is 1150-1180 ℃, and the total heating time is more than or equal to 220 min; tapping temperature: 1050-1180 ℃; the initial rolling temperature of the rolling step is 1030-1075 ℃, and the final rolling temperature is 890-960 ℃. Finally, finishing and checking are carried out; the method can improve the surface quality, reduce the problems of surface microcracks, cracking sources of longitudinal cracks and the like, improve the qualification rate of the surface quality of the rolled 20Cr steel bar hot-rolled round steel from less than or equal to 60 percent to more than or equal to 90 percent of the traditional process, has obvious effect and improves the economic benefit.
Description
Technical Field
The invention belongs to the technical field of steel rolling, and particularly relates to a rolling process for improving the surface quality of 20Cr steel bar hot-rolled round steel.
Background
The 20Cr steel is the most typical basic variety in the chromium alloy structural steel, has huge market demand, and is widely used for manufacturing carburized parts such as gears, gear shafts, cams, piston pins, worms and the like, which have higher core strength requirement, wear-resisting surface, cross-sectional dimension below 30mm or more complex shapes and low load in the manufacturing industries such as automobiles, mining machinery and the like; or used for parts requiring small heat treatment deformation and high wear resistance, and high-frequency surface quenching can be carried out after carburization; or used for hardening and tempering parts which have high working speed and bear medium impact load, and plays an important role in national economy and national defense construction in China.
With the progress of steel-making equipment and level, the purity of steel is continuously improved, and factors for restricting the hot upsetting performance of 20Cr steel are mainly concentrated in a rolling process. In recent years, market demands are increased, but at present, all production and use units basically adopt normalizing, tempering and other processes for production, and because round steel is subjected to two heat treatment processes of normalizing and tempering, the process flow is complex and the requirements on equipment are strict, and on the other hand, the production and manufacturing cost is increased.
Therefore, the good surface quality of the product is ensured by adjusting the rolling process so as to reduce the cracking sources of surface microcracks and longitudinal cracks, avoid surface defects and improve the surface quality, which is a technical problem to be solved urgently.
Disclosure of Invention
The invention aims to provide a rolling process for improving the surface quality of 20Cr steel bar hot-rolled round steel, which can ensure good surface quality of products and reduce related problems of surface microcracks, cracking sources of longitudinal cracks and the like.
In order to achieve the purpose, the invention provides a rolling process for improving the surface quality of 20Cr steel bar hot-rolled round steel, which comprises the following specific operation steps:
(1) weighing the components according to the weight of each chemical component, mixing the components, smelting, and casting into a steel billet; heating the steel billet and carrying out hot rolling; the temperature of the billet preheating section is 600-710 ℃, and the heating 1 section is 940-980 ℃; the temperature of the heating 2 sections is 1150-1180 ℃; the temperature of the soaking section is 1150-1180 ℃; wherein the soaking period time is 35-85 min, the total heating time is more than or equal to 220min, the steel billet is discharged after being completely and uniformly and thoroughly burnt, and the target tapping temperature is 1050-1180 ℃;
(2) rolling the hot rolled material, starting high-pressure water to remove phosphorus, and rolling the hot rolled material by a rolling mill after the phosphorus removal is finished;
(3) the initial rolling temperature is 1030-1075 ℃, and the final rolling temperature is 890-960 ℃;
(4) finally, finishing and checking are carried out;
the 20Cr steel bar comprises the following components in percentage by weight:
c: 0.18 to 0.22, Si: 0.17-0.35, Mn: 0.50-0.80, P: less than or equal to 0.020 and S: less than or equal to 0.015, Cr: 0.70-1.00, Als: less than or equal to 0.050, and the balance of Fe and inevitable impurities.
Preferably, in the step (1), the billet heating adopts a high-efficiency walking beam type heating furnace, and a control system is formed by an industrial microcomputer and a PLC (programmable logic controller), so that automatic combustion can be realized according to set parameters.
Preferably, in the step (1), the total heating time is 220-260 min.
Preferably, in the step (1), the target tapping temperature is 1145-1150 ℃.
Preferably, in the step (2), the dephosphorization pressure is 15-20 MPa.
The invention has the advantages and the technical effects that:
(1) the high-efficiency walking beam type heating furnace is adopted, a control system is formed by an industrial microcomputer and a PLC, automatic combustion can be realized according to set parameters, and the high-efficiency walking beam type heating furnace has the advantages of flexible production operation, uniform heating of steel billets, less oxidation burning loss, energy conservation and the like.
(2) The method is simple and easy to implement and low in cost, and the 20Cr steel bar which is thin and compact on the surface, difficult to damage, high in surface smoothness and high in surface quality and has no pitted surface is obtained by improving the rolling cooling process, rolling, removing phosphorus and controlling temperature related parameters.
(3) The invention utilizes the existing equipment and process conditions of steel mills to obtain the 20Cr steel bar with high surface quality, which not only does not increase investment and production cost, but also improves production efficiency and economic benefit, saves energy and reduces consumption.
Detailed Description
The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
Example 1:
(1) weighing the components according to the weight of each chemical component, mixing the components, smelting, and casting into a steel billet; heating the steel billet and then carrying out hot rolling; the temperature of the billet preheating section is 700 ℃; the temperature of the heating section 1 is 980 ℃; heating the mixture for 2 sections at the temperature of 1150 ℃; the temperature of the soaking section is 1150 ℃, the time of the soaking section is 35min, the total heating time is 220min, the steel billet is discharged after being completely and completely burned, and the target tapping temperature is 1145 ℃;
(2) rolling the hot rolled material, starting high-pressure water to remove phosphorus, wherein the phosphorus removal pressure is 18MPa, and rolling the hot rolled material by a rolling mill after the phosphorus removal is finished;
(3) the initial rolling temperature is 1030 ℃, and the final rolling temperature is 900 ℃;
(4) finally, finishing and checking are carried out;
the 20Cr steel bar comprises the following components in percentage by weight:
c: 0.22, Si: 0.25, Mn: 0.60, P: 0.016, S: 0.010, Cr: 0.85, Als: 0.050, and the balance of Fe and inevitable impurities.
Example 2:
(1) weighing the components according to the weight of each chemical component, mixing the components, smelting, and casting into a steel billet; heating the steel billet and then carrying out hot rolling; the temperature of the billet preheating section is 690 ℃; heating the mixture at 1 section at 970 ℃; heating for 2 sections at the temperature of 1160 ℃; the temperature of the soaking section is 1160 ℃, the time of the soaking section is 45min, the total heating time is 240min, the steel billet is discharged after being completely and completely burned, and the target tapping temperature is 1150 ℃;
(2) rolling the hot rolled material, starting high-pressure water to remove phosphorus, wherein the phosphorus removal pressure is 20MPa, and rolling the hot rolled material by a rolling mill after the phosphorus removal is finished;
(3) the initial rolling temperature is 1050 ℃, and the final rolling temperature is 890 ℃;
(4) finally, finishing and checking are carried out;
the 20Cr steel bar comprises the following components in percentage by weight:
c: 0.20, Si: 0.26, Mn: 0.60, P: 0.014, S: 0.009, Cr: 0.95, Als: 0.030, and the balance being Fe and unavoidable impurities.
Example 3:
(1) weighing the components according to the weight of each chemical component, mixing the materials, smelting and casting into a steel billet; heating the steel billet and then carrying out hot rolling; the temperature of the billet preheating section is 700 ℃; the temperature of the heating stage 1 is 950 ℃; heating to 1180 ℃ at 2 stages; the temperature of the soaking section is 1180 ℃, the time of the soaking section is 50min, the total heating time is 260min, the steel billet is discharged after being completely and completely burned, and the target tapping temperature is 1150 ℃;
(2) rolling the hot rolled material, starting high-pressure water to remove phosphorus, wherein the phosphorus removal pressure is 15MPa, and rolling the hot rolled material by a rolling mill after the phosphorus removal is finished;
(3) the initial rolling temperature is 1060 ℃, and the final rolling temperature is 910 ℃;
(4) finally, finishing and checking are carried out;
the 20Cr steel bar comprises the following components in percentage by weight:
c: 0.19, Si: 0.28, Mn: 0.60, P: 0.016, S: 0.008, Cr: 0.99, Als: 0.040, balance Fe and unavoidable impurities.
Through observation, the 20Cr steel bar prepared in the embodiment 1-3 is hot-rolled into round steel to obtain a thin and compact iron scale which is not easy to damage and has high surface smoothness, no pitted surface and better bending degree of the round steel.
Examples 1 to 3, the prepared 20Cr steel rod hot rolled round steel was subjected to magnetic flux leakage testing with the accuracy according to depth × width × length: 0.3 mm. times.0.2 mm. times.25 mm, the specific results are given in Table 1.
Table 1: magnetic leakage qualification rate of round steel
| Examples | Total amount of assay (root) | Number of qualified products | Number of defects | Percent of pass |
| Example 1 | 150 | 138 | 12 | 92％ |
| Example 2 | 120 | 113 | 7 | 94.2％ |
| Example 3 | 120 | 109 | 11 | 90.8％ |
As can be seen from the table 1, the rolling process provided by the invention has the advantages that the surface quality is obviously improved, the qualified rate is over 90%, and the cost reduction and gain effects are obvious.
Description of the invention: the above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention; thus, while the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted; all such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.
Claims (5)
1. A rolling process for improving the surface quality of 20Cr steel bar hot-rolled round steel is characterized by comprising the following steps:
(1) weighing the components according to the weight of each chemical component, mixing the materials, smelting, casting into a steel billet, and heating the steel billet; the temperature of the billet preheating section is 600-710 ℃, the temperature of the heating section 1 is 940-980 ℃, the temperature of the heating section 2 is 1150-1180 ℃, and the temperature of the soaking section is 1150-1180 ℃; wherein the soaking period is 35-85 min, the total heating time is more than or equal to 220min, the steel billet is discharged after being completely and uniformly burnt, and the target tapping temperature is 1050-1180 ℃;
(2) rolling the hot rolled material, starting high-pressure water to remove phosphorus, and rolling the hot rolled material by a rolling mill after the phosphorus removal is finished;
(3) the initial rolling temperature is 1030-1075 ℃, and the final rolling temperature is 890-960 ℃;
(4) finally, finishing and checking are carried out;
the 20Cr steel bar comprises the following components in percentage by weight:
c: 0.18 to 0.22, Si: 0.17-0.35, Mn: 0.50-0.80, P: less than or equal to 0.020S: less than or equal to 0.015, Cr: 0.70-1.00, Als: less than or equal to 0.050 percent, and the balance of Fe and inevitable impurities.
2. The rolling process for improving the surface quality of hot-rolled round steel of a 20Cr steel bar according to claim 1, wherein in the step (1), the billet is heated by a high-efficiency walking beam type heating furnace, and a control system consisting of an industrial microcomputer and a PLC (programmable logic controller) can realize automatic combustion according to set parameters.
3. The rolling process for improving the surface quality of the hot-rolled round steel of the 20Cr steel bar according to claim 1, wherein in the step (1), the total heating time is 220-260 min.
4. The rolling process for improving the surface quality of hot-rolled round steel of a 20Cr steel bar according to claim 1, wherein in the step (1), the target tapping temperature is 1145-1150 ℃.
5. The rolling process for improving the surface quality of the hot-rolled 20Cr steel rod round steel according to claim 1, wherein in the step (2), the dephosphorization pressure is 15-20 MPa.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210426016.3A CN114769315A (en) | 2022-04-22 | 2022-04-22 | Rolling process for improving surface quality of 20Cr steel bar hot-rolled round steel |
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| CN202210426016.3A CN114769315A (en) | 2022-04-22 | 2022-04-22 | Rolling process for improving surface quality of 20Cr steel bar hot-rolled round steel |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1017928A (en) * | 1996-06-28 | 1998-01-20 | Kawasaki Steel Corp | Production of gear steel stock for induction hardening, excellent in machinability and fatigue strength |
| CN103882201A (en) * | 2014-03-19 | 2014-06-25 | 武汉钢铁(集团)公司 | Rolling process capable of improving hot-upsetting performance of 20 Cr steel |
| CN107225148A (en) * | 2017-06-01 | 2017-10-03 | 马鞍山钢铁股份有限公司 | A kind of milling method of 22CrMoH pinion steels |
| CN111957745A (en) * | 2020-07-10 | 2020-11-20 | 山东钢铁股份有限公司 | Hot rolling controlled cooling method for low-alloy high-strength large-size bar |
| CN113817967A (en) * | 2021-09-28 | 2021-12-21 | 联峰钢铁（张家港）有限公司 | Hot-delivery hot-charging production method for reducing depth of decarburized layer of bearing steel round steel |
-
2022
- 2022-04-22 CN CN202210426016.3A patent/CN114769315A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1017928A (en) * | 1996-06-28 | 1998-01-20 | Kawasaki Steel Corp | Production of gear steel stock for induction hardening, excellent in machinability and fatigue strength |
| CN103882201A (en) * | 2014-03-19 | 2014-06-25 | 武汉钢铁(集团)公司 | Rolling process capable of improving hot-upsetting performance of 20 Cr steel |
| CN107225148A (en) * | 2017-06-01 | 2017-10-03 | 马鞍山钢铁股份有限公司 | A kind of milling method of 22CrMoH pinion steels |
| CN111957745A (en) * | 2020-07-10 | 2020-11-20 | 山东钢铁股份有限公司 | Hot rolling controlled cooling method for low-alloy high-strength large-size bar |
| CN113817967A (en) * | 2021-09-28 | 2021-12-21 | 联峰钢铁（张家港）有限公司 | Hot-delivery hot-charging production method for reducing depth of decarburized layer of bearing steel round steel |
Non-Patent Citations (1)
| Title |
|---|
| 鞠幼华: "《现代冶金热能理论与应用》", 吉林科学技术出版社, pages: 279 - 281 * |
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