CN113174472A - Control method for surface precipitation of high-strength steel with hot galvanizing strength of more than 590MPa - Google Patents
Control method for surface precipitation of high-strength steel with hot galvanizing strength of more than 590MPa Download PDFInfo
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- CN113174472A CN113174472A CN202110356322.XA CN202110356322A CN113174472A CN 113174472 A CN113174472 A CN 113174472A CN 202110356322 A CN202110356322 A CN 202110356322A CN 113174472 A CN113174472 A CN 113174472A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/76—Adjusting the composition of the atmosphere
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D11/00—Process control or regulation for heat treatments
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Abstract
The invention discloses a control method for surface precipitation of high-strength steel with hot galvanizing strength of more than 590MPa, which adjusts the oxygen content and dew point in a pre-oxidation chamber by adjusting the amount of air injected into the pre-oxidation chamber of the hot galvanizing, realizes the internal oxidation of strip steel in an annealing furnace and achieves the purpose of inhibiting the precipitation of alloy elements; meanwhile, the reduction effect is controlled by adjusting the hydrogen content of the cooling section. The invention controls the precipitation of alloy elements of the high-strength steel hot-dip galvanized plate with more than 590MPa through the optimized regulation of the atmosphere in the furnace, thereby improving the surface quality and realizing the defect-free production of the surface of a high-strength product.
Description
Technical Field
The invention belongs to the technical field of steel rolling heat treatment, and relates to a control method for surface precipitation of hot-galvanized high-strength steel with strength higher than 590 MPa.
Background
The advanced high-strength steel of the grade above 590MPa of hot galvanizing needs to add a certain amount of alloy elements into the product to realize the strength of the product, and the added alloy elements are still oxidized by oxygen remained in a furnace even under the environment of protective atmosphere in the furnace to cause poor galvanizing, namely the selective oxidation of the hot galvanizing. At present, the existing hot galvanizing has almost no effective control means for element precipitation, and the precipitation degree can be reduced only by reducing the residence time of strip steel in a furnace.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a method for controlling the surface precipitation of high-strength steel with the strength of more than 590MPa of hot galvanizing, which controls the dew point in a pre-oxidation chamber of the hot galvanizing and is matched with a high-hydrogen reduction mode subsequently.
The invention provides a method for controlling surface precipitation of high-strength steel with hot galvanizing strength of more than 590MPa, which comprises the following steps:
step 1: controlling the area temperature of a pre-oxidation chamber of the annealing furnace to be 700-750 ℃, closing a sealing roller of the pre-oxidation chamber, starting a heat preservation device and an atmosphere heating device of the pre-oxidation chamber area, and heating the atmosphere to be between 280-350 ℃;
step 2: after the atmosphere temperature reaches the set requirement, introducing nitrogen to seal the inlet and the outlet, and simultaneously starting pre-oxidized atmosphere detection equipment;
and step 3: opening a compressed air valve, introducing compressed air into the mixed atmosphere, and gradually increasing the indoor oxygen content and the atmosphere dew point;
and 4, step 4: when the atmosphere dew point reaches-25 ℃ to-5 ℃, reducing the introduction amount of compressed air to keep the dew point stable;
and 5: introducing hydrogen into a cooling section of the annealing furnace to ensure that the concentration of the hydrogen reaches 12-17%;
step 6: after the target product enters the pre-oxidation chamber, adjusting the air injection amount to reach the specified amount, and controlling the dew point to keep stable;
and 7: and after the production is finished, the compressed air is closed, and other equipment in the area is closed when the atmosphere to be detected is kept constant with the atmosphere in the furnace.
In the method for controlling the surface precipitation of the high-strength steel with the strength of more than 590MPa of hot galvanizing, the oxygen content in the step 6 is 0.7-3%.
According to the control method for the surface precipitation of the high-strength steel with the hot galvanizing strength of more than 590MPa, the oxygen content and the dew point in the pre-oxidation chamber are adjusted by adjusting the air quantity injected into the hot galvanizing pre-oxidation chamber, so that the strip steel is internally oxidized in the annealing furnace, and the purpose of inhibiting the precipitation of alloy elements is achieved; meanwhile, the reduction effect is controlled by adjusting the hydrogen content of the cooling section. The invention controls the precipitation of alloy elements of the high-strength steel hot-dip galvanized plate with more than 590MPa through the optimized regulation of the atmosphere in the furnace, thereby improving the surface quality and realizing the defect-free production of the surface of a high-strength product.
Drawings
FIG. 1a is a surface view of a product with a prior hot dip galvanizing pressure above 590 MPa;
FIG. 1b is a surface view of a product obtained by the method for controlling surface precipitation of high-strength steel with strength of over 590MPa by hot galvanizing.
Detailed Description
Due to selective oxidation, precipitation defects appear on the surface of a high-strength product with the production level of more than 590MPa, and the precipitation defects can be influenced to a certain extent by optimizing unit parameters because the defect generating parts are positioned in an annealing furnace, but the precipitation defects cannot be controlled fundamentally.
Aiming at the problems, the invention provides a method for controlling the surface precipitation of high-strength steel with hot galvanizing strength of more than 590MPa, which comprises the following steps:
step 1: controlling the area temperature of a pre-oxidation chamber of the annealing furnace to be 700-750 ℃, closing a sealing roller of the pre-oxidation chamber, starting a heat preservation device and an atmosphere heating device of the pre-oxidation chamber area, and heating the atmosphere to be between 280-350 ℃;
in specific implementation, the hot galvanizing preoxidation chamber is positioned at the rear part of the annealing furnace, the temperature of the region is 700-750 ℃, and other parameters of the annealing furnace are adjusted according to the fixed position.
Step 2: after the atmosphere temperature reaches the set requirement, introducing nitrogen to seal an inlet and an outlet, and simultaneously starting pre-oxidized atmosphere detection equipment for real-time monitoring;
and step 3: opening a compressed air valve, introducing compressed air into the mixed atmosphere, and gradually increasing the indoor oxygen content and the atmosphere dew point;
and 4, step 4: when the atmosphere dew point reaches-25 ℃ to-5 ℃, reducing the introduction amount of compressed air to keep the dew point stable;
and 5: introducing hydrogen into a cooling section of the annealing furnace to ensure that the concentration of the hydrogen reaches 12-17%;
step 6: after the target product enters the pre-oxidation chamber, adjusting the air injection amount to reach the specified amount, wherein the oxygen content is 0.7-3%, and controlling the dew point to keep stable;
and 7: and after the production is finished, the compressed air is closed, and other equipment in the area is closed when the atmosphere to be detected is kept constant with the atmosphere in the furnace.
The invention realizes the internal oxidation of the strip steel in the annealing furnace by controlling the injection amount of the oxidizing atmosphere of the pre-oxidation chamber in the annealing furnace and adjusting the region dew point of the oxidizing section atmosphere, thereby achieving the purpose of inhibiting the precipitation of alloy elements; and subsequently, the hydrogen content and the reduction effect are controlled, so that the defect-free production of the surface of the high-strength product is realized.
The high-strength steel with the pressure of more than 590MPa mainly comprises the following steel types: DP590 series, DP780 series, DP980-1180 series; TRIP590 series, TRIP780 series, and CP780-1180 series. The invention can control the precipitation of the alloy element of the high-strength steel hot-dip galvanized plate with more than 590MPa, thereby improving the surface quality.
FIG. 1a is a surface view of a product of a conventional hot dip galvanizing at 590MPa or more, and the product has poor wettability during galvanizing due to selective oxidation of alloying elements in a furnace, and mainly shows a mountain water streak-like precipitation defect on the surface of strip steel.
FIG. 1b is a surface view of a product obtained by the method for controlling surface precipitation of high-strength steel with strength of over 590MPa subjected to hot galvanizing, and the product has good surface quality and stable micro-analysis components.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the scope of the present invention, which is defined by the appended claims.
Claims (2)
1. The method for controlling the surface precipitation of the high-strength steel with the hot galvanizing strength of more than 590MPa is characterized by comprising the following steps of:
step 1: controlling the area temperature of a pre-oxidation chamber of the annealing furnace to be 700-750 ℃, closing a sealing roller of the pre-oxidation chamber, starting a heat preservation device and an atmosphere heating device of the pre-oxidation chamber area, and heating the atmosphere to be between 280-350 ℃;
step 2: after the atmosphere temperature reaches the set requirement, introducing nitrogen to seal the inlet and the outlet, and simultaneously starting pre-oxidized atmosphere detection equipment;
and step 3: opening a compressed air valve, introducing compressed air into the mixed atmosphere, and gradually increasing the indoor oxygen content and the atmosphere dew point;
and 4, step 4: when the atmosphere dew point reaches-25 ℃ to-5 ℃, reducing the introduction amount of compressed air to keep the dew point stable;
and 5: introducing hydrogen into a cooling section of the annealing furnace to ensure that the concentration of the hydrogen reaches 12-17%;
step 6: after the target product enters the pre-oxidation chamber, adjusting the air injection amount to reach the specified amount, and controlling the dew point to keep stable;
and 7: and after the production is finished, the compressed air is closed, and other equipment in the area is closed when the atmosphere to be detected is kept constant with the atmosphere in the furnace.
2. The method for controlling surface precipitation of high-strength steel with strength of more than 590MPa for hot galvanizing according to claim 1, wherein the oxygen content in the step 6 is 0.7% -3%.
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| CN202110356322.XA CN113174472A (en) | 2021-04-01 | 2021-04-01 | Control method for surface precipitation of high-strength steel with hot galvanizing strength of more than 590MPa |
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| CN202110356322.XA CN113174472A (en) | 2021-04-01 | 2021-04-01 | Control method for surface precipitation of high-strength steel with hot galvanizing strength of more than 590MPa |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114855108A (en) * | 2022-05-24 | 2022-08-05 | 山东钢铁集团日照有限公司 | Control method for surface plating leakage and zinc ash defects of high-aluminum-silicon-manganese galvanized dual-phase steel |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1088305A (en) * | 1996-09-10 | 1998-04-07 | Nkk Corp | Production of galvanized steel sheet |
| CN206319032U (en) * | 2016-12-09 | 2017-07-11 | 中冶南方工程技术有限公司 | A kind of cold-strip steel pre-oxidizes device |
| CN107747078A (en) * | 2017-11-01 | 2018-03-02 | 攀钢集团攀枝花钢铁研究院有限公司 | A kind of method for preparing coating during hot-dip galvanized high-strength steel |
| CN110172640A (en) * | 2019-05-30 | 2019-08-27 | 安徽工业大学 | 500MPa grades high work hardening rate hot dip galvanized dual phase steel plate and preparation method thereof |
| CN110878386A (en) * | 2018-09-06 | 2020-03-13 | 本钢板材股份有限公司 | Low-cost hot-galvanized phase-change induced plasticity steel and preparation method thereof |
| CN112281062A (en) * | 2020-10-22 | 2021-01-29 | 本钢板材股份有限公司 | 1000 MPa-grade low-cost hot-galvanized dual-phase steel and preparation method thereof |
-
2021
- 2021-04-01 CN CN202110356322.XA patent/CN113174472A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1088305A (en) * | 1996-09-10 | 1998-04-07 | Nkk Corp | Production of galvanized steel sheet |
| CN206319032U (en) * | 2016-12-09 | 2017-07-11 | 中冶南方工程技术有限公司 | A kind of cold-strip steel pre-oxidizes device |
| CN107747078A (en) * | 2017-11-01 | 2018-03-02 | 攀钢集团攀枝花钢铁研究院有限公司 | A kind of method for preparing coating during hot-dip galvanized high-strength steel |
| CN110878386A (en) * | 2018-09-06 | 2020-03-13 | 本钢板材股份有限公司 | Low-cost hot-galvanized phase-change induced plasticity steel and preparation method thereof |
| CN110172640A (en) * | 2019-05-30 | 2019-08-27 | 安徽工业大学 | 500MPa grades high work hardening rate hot dip galvanized dual phase steel plate and preparation method thereof |
| CN112281062A (en) * | 2020-10-22 | 2021-01-29 | 本钢板材股份有限公司 | 1000 MPa-grade low-cost hot-galvanized dual-phase steel and preparation method thereof |
Non-Patent Citations (2)
| Title |
|---|
| 郑怀宇等: "590TRIP热镀锌产品露钢缺陷控制工艺优化", 《轧钢》 * |
| 马峰: "热镀锌生产过程中预氧化与还原控制技术研究", 《本钢技术》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114855108A (en) * | 2022-05-24 | 2022-08-05 | 山东钢铁集团日照有限公司 | Control method for surface plating leakage and zinc ash defects of high-aluminum-silicon-manganese galvanized dual-phase steel |
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