CN110669983A - Production method of steel Q235-DG hot rolled plate for low-pressure pipe industry - Google Patents
Production method of steel Q235-DG hot rolled plate for low-pressure pipe industry Download PDFInfo
- Publication number
- CN110669983A CN110669983A CN201911076707.XA CN201911076707A CN110669983A CN 110669983 A CN110669983 A CN 110669983A CN 201911076707 A CN201911076707 A CN 201911076707A CN 110669983 A CN110669983 A CN 110669983A
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- China
- Prior art keywords
- steel
- low
- pressure pipe
- hot rolled
- pipe industry
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Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention discloses a production method of a Q235-DG hot rolled plate for punching low-pressure pipe industry, which sequentially comprises the process steps of molten iron desulphurization, converter steelmaking, LF refining, continuous casting and hot rolling, wherein the content ratio range of Mn element and S element in molten steel is controlled to be 6-7 in the converter steelmaking and LF refining steps. According to the invention, the production process of the steel Q235-DG for the low-pressure pipe industry is improved, and the content ratio of Mn element and S element causing the edge cracking defect of the hot rolled plate in the process is controlled, so that the occurrence rate of the edge cracking defect of the hot rolled plate is reduced from 3% to below 0.2%, the defect rate is greatly reduced, and the economic loss caused by edge cutting and scrapping of the hot rolled plate is greatly reduced.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to a production method of a Q235-DG hot rolled plate made of steel for low-pressure pipe industry.
Background
The steel Q235-DG for the low-pressure pipe industry is a low-cost steel developed by the applicant in 2016, and can effectively reduce the cost of the steel for the low-pressure pipe industry. In the component design of the Q235-DG steel grade, the content range of Mn element is 0.10-0.20%, and the content range of S element is 0.015-0.025%. In the production process of Q235-DG steel, in order to reduce the production cost, the content of Mn element is controlled according to the lower limit, the content of S element is controlled according to the middle upper limit, the occurrence rate of edge crack defects of the final hot rolled plate coil finished product is up to more than 3%, the edge cutting operation is required to be carried out on the hot rolled plate coil with the edge crack defects to remove the edge defects, the hot rolled plate coil with serious edge crack defects is directly scrapped, and the average annual loss is more than 270 ten thousand yuan.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the production method of the steel Q235-DG hot rolled plate for the low-pressure pipe industry is provided, and the incidence rate of the edge rolling crack defect of the hot rolled plate can be effectively reduced.
In order to solve the technical problems, the invention adopts the technical scheme that: the production method of the Q235-DG hot rolled steel plate for the low-pressure pipe industry sequentially comprises the process steps of molten iron desulphurization, converter steelmaking, LF refining, continuous casting and hot rolling, wherein the content ratio of Mn element to S element in molten steel is controlled to be 6-7 in the converter steelmaking and LF refining steps.
Further, the method comprises the following steps: in the step of molten iron desulphurization, the proportion of the S element in the desulfurized molten iron is controlled to be less than or equal to 0.02 percent.
Further, the method comprises the following steps: in the LF refining step, if the content ratio of Mn element to S element in molten steel is less than 6, carrying out secondary desulfurization treatment on the molten steel.
Further, the method comprises the following steps: and in the LF refining step, high-alkalinity refining slag is added for secondary desulfurization treatment.
Further, the method comprises the following steps: in the converter steelmaking step, under the premise of ensuring that the content of the Mn element in the molten steel is within 0.10-0.20%, adding the ferromanganese alloy to carry out the alloying of the Mn element.
The invention has the beneficial effects that: according to the invention, the production process of the steel Q235-DG for the low-pressure pipe industry is improved, the content ratio of Mn element and S element causing the edge crack defect of the hot rolled plate coil in the process is controlled, the occurrence rate of the edge crack defect of the hot rolled plate coil is reduced from 3% to below 0.2%, the defect rate is greatly reduced, and the economic loss caused by the edge cutting and scrapping of the hot rolled plate is greatly reduced.
Detailed Description
In order to facilitate an understanding of the invention, the invention is further described below.
The production method of the Q235-DG hot rolled steel for the low-pressure pipe industry comprises the steps of molten iron desulphurization, converter steel making, LF refining, continuous casting and hot rolling, and the inventor researches the reasons for the edge crack defect of the finished hot rolled steel coil, and finds that when the ratio of [ Mn ]/[ S ] in the finished hot rolled steel coil is less than 6, the probability of the edge crack defect of the corresponding hot rolled steel coil is higher than 30%, so that the production process of the Q235-DG hot rolled steel plate is optimized and improved, and the content ratio range of Mn element to S element in molten steel is controlled to be 6-7 in the two steps of converter steel making and LF refining.
The molten iron desulphurization step is an important process for removing the S element in the molten steel, and because the content range of the S element in the components of the Q235-DG steel grade needs to be controlled to be 0.015-0.025%, and the molten steel can be desulfurized again in the subsequent steps in order to ensure the ratio range of [ Mn ]/[ S ], the content of the S element in the molten iron is not easy to be controlled to be too low in the step, and the proportion of the S element in the desulfurized molten iron is preferably controlled to be less than or equal to 0.02%.
In the LF refining step, if the content ratio of Mn element to S element in molten steel is less than 6, adding high-alkalinity refining slag into the molten steel for secondary desulfurization treatment, and finely adjusting the content of the S element to ensure that the content ratio of the Mn element to the S element is within the range of 6-7; in the converter steelmaking step, under the premise of ensuring that the content ratio of the Mn element in molten steel is within 0.10-0.20%, adding ferromanganese alloy to carry out Mn element alloying, and ensuring that the content ratio of the Mn element to the S element in a continuous casting finished product is within 6-7.
After the production method of the Q235-DG hot rolled steel plate for the low-pressure pipe industry is adopted, the applicant unit implements the method from 2019 in 1 month, the edge crack defect incidence rate of the Q235-DG hot rolled steel plate coil is reduced to below 0.2% from the previous 3%, the loss of the hot rolled plate coil caused by edge cutting saving and scrapping treatment is reduced by more than 1200 tons, the economic loss can be reduced by more than 200 ten thousand yuan every year, and very remarkable effect is achieved.
Claims (5)
1. The production method of the steel Q235-DG hot rolled plate for the low-pressure pipe industry sequentially carries out the process steps of molten iron desulphurization, converter steelmaking, LF refining, continuous casting and hot rolling, and is characterized in that: in the steps of converter steelmaking and LF refining, the content ratio of Mn element to S element in molten steel is controlled to be 6-7.
2. The method for producing a hot-rolled steel Q235-DG plate for low-pressure pipe industry as claimed in claim 1, wherein: in the step of molten iron desulphurization, the proportion of the S element in the desulfurized molten iron is controlled to be less than or equal to 0.02 percent.
3. The method for producing a hot-rolled steel Q235-DG plate for low-pressure pipe industry as claimed in claim 1, wherein: in the LF refining step, if the content ratio of Mn element to S element in molten steel is less than 6, carrying out secondary desulfurization treatment on the molten steel.
4. The method for producing a hot-rolled steel Q235-DG plate for low-pressure pipe industry as claimed in claim 3, wherein: and in the LF refining step, high-alkalinity refining slag is added for secondary desulfurization treatment.
5. The method for producing a hot-rolled steel Q235-DG plate for low-pressure pipe industry as claimed in claim 1, wherein: in the converter steelmaking step, under the premise of ensuring that the content of the Mn element in the molten steel is within 0.10-0.20%, adding the ferromanganese alloy to carry out the alloying of the Mn element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911076707.XA CN110669983A (en) | 2019-11-06 | 2019-11-06 | Production method of steel Q235-DG hot rolled plate for low-pressure pipe industry |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911076707.XA CN110669983A (en) | 2019-11-06 | 2019-11-06 | Production method of steel Q235-DG hot rolled plate for low-pressure pipe industry |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110669983A true CN110669983A (en) | 2020-01-10 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911076707.XA Pending CN110669983A (en) | 2019-11-06 | 2019-11-06 | Production method of steel Q235-DG hot rolled plate for low-pressure pipe industry |
Country Status (1)
| Country | Link |
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| CN (1) | CN110669983A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5857491B2 (en) * | 1980-05-27 | 1983-12-20 | 住友金属工業株式会社 | Method for producing thermosetting cold-rolled steel sheet for deep drawing |
| CN101745794A (en) * | 2008-12-15 | 2010-06-23 | 鞍钢股份有限公司 | Preparation technology of non-oriented high grade silicon steel |
| CN102179407A (en) * | 2011-03-17 | 2011-09-14 | 宁波钢铁有限公司 | Method for preparing hot rolling strip steel capable of preventing edge crack of extremely thin rolled strip steel |
| CN104195442A (en) * | 2014-07-24 | 2014-12-10 | 安徽广源科技发展有限公司 | Wear-resisting low carbon automotive steel material and manufacturing technique thereof |
-
2019
- 2019-11-06 CN CN201911076707.XA patent/CN110669983A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5857491B2 (en) * | 1980-05-27 | 1983-12-20 | 住友金属工業株式会社 | Method for producing thermosetting cold-rolled steel sheet for deep drawing |
| CN101745794A (en) * | 2008-12-15 | 2010-06-23 | 鞍钢股份有限公司 | Preparation technology of non-oriented high grade silicon steel |
| CN102179407A (en) * | 2011-03-17 | 2011-09-14 | 宁波钢铁有限公司 | Method for preparing hot rolling strip steel capable of preventing edge crack of extremely thin rolled strip steel |
| CN104195442A (en) * | 2014-07-24 | 2014-12-10 | 安徽广源科技发展有限公司 | Wear-resisting low carbon automotive steel material and manufacturing technique thereof |
Non-Patent Citations (1)
| Title |
|---|
| 罗莉萍: "《炼钢生产》", 28 February 2016, 北京：冶金工业出版社 * |
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Application publication date: 20200110 |
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