CN114807805A - Hot galvanizing production method for high-strength steel and ultrahigh-strength steel - Google Patents
Hot galvanizing production method for high-strength steel and ultrahigh-strength steel Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 94
- 239000010959 steel Substances 0.000 title claims abstract description 94
- 238000005246 galvanizing Methods 0.000 title claims abstract description 69
- 229910000797 Ultra-high-strength steel Inorganic materials 0.000 title claims abstract description 23
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
- 238000001816 cooling Methods 0.000 claims abstract description 73
- 238000010438 heat treatment Methods 0.000 claims abstract description 43
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 42
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 42
- 239000011701 zinc Substances 0.000 claims abstract description 42
- 238000000034 method Methods 0.000 claims abstract description 40
- 230000001681 protective effect Effects 0.000 claims abstract description 34
- 230000008569 process Effects 0.000 claims abstract description 33
- 239000000243 solution Substances 0.000 claims abstract description 33
- 239000007788 liquid Substances 0.000 claims abstract description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 31
- UMGDCJDMYOKAJW-UHFFFAOYSA-N thiourea Chemical compound NC(N)=S UMGDCJDMYOKAJW-UHFFFAOYSA-N 0.000 claims abstract description 28
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000010791 quenching Methods 0.000 claims abstract description 24
- 230000000171 quenching effect Effects 0.000 claims abstract description 24
- 238000002791 soaking Methods 0.000 claims abstract description 22
- 238000005406 washing Methods 0.000 claims abstract description 22
- 239000002253 acid Substances 0.000 claims abstract description 18
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Natural products NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000003513 alkali Substances 0.000 claims abstract description 14
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910001335 Galvanized steel Inorganic materials 0.000 claims abstract description 12
- 239000008397 galvanized steel Substances 0.000 claims abstract description 12
- 239000011259 mixed solution Substances 0.000 claims abstract description 11
- 239000004519 grease Substances 0.000 claims abstract description 8
- 238000004140 cleaning Methods 0.000 claims abstract description 7
- 239000007789 gas Substances 0.000 claims description 43
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 42
- 229910052757 nitrogen Inorganic materials 0.000 claims description 21
- 239000001257 hydrogen Substances 0.000 claims description 19
- 229910052739 hydrogen Inorganic materials 0.000 claims description 19
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 10
- 239000001301 oxygen Substances 0.000 claims description 10
- 229910052760 oxygen Inorganic materials 0.000 claims description 10
- 239000011261 inert gas Substances 0.000 claims description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 229910045601 alloy Inorganic materials 0.000 description 7
- 239000000956 alloy Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 238000005554 pickling Methods 0.000 description 6
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 5
- 150000002431 hydrogen Chemical class 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 4
- 229910000734 martensite Inorganic materials 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000012459 cleaning agent Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 235000010299 hexamethylene tetramine Nutrition 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/08—Iron or steel
- C23G1/081—Iron or steel solutions containing H2SO4
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/14—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions
- C23G1/19—Iron or steel
Abstract
The invention relates to a hot galvanizing production method of high-strength steel and ultrahigh-strength steel, which comprises the following steps of (1) alkali washing: cleaning with alkali liquor to remove residues and grease on the surface of the steel plate of the high-strength steel or the ultrahigh-strength steel; (2) heating and soaking: introducing protective gas in the heating and soaking processes; (3) water quenching and cooling: placing the steel plate after soaking treatment into water to be rapidly cooled to room temperature; introducing protective gas in the cooling process; (4) acid washing: cleaning an oxide film on the surface of the steel plate after water quenching and cooling by adopting a mixed solution of a sulfuric acid solution, a thiourea solution and a urotropine solution; (5) secondary heating: carrying out secondary heating on the steel plate in protective gas, wherein the heating temperature is consistent with the temperature of the hot galvanizing zinc liquid; (6) hot galvanizing: immersing the secondarily heated steel plate into molten zinc liquid in protective gas, and carrying out hot galvanizing treatment; (7) and (3) final cooling: and cooling the hot-galvanized steel plate to room temperature to finish the whole hot-galvanizing process. The invention has the advantages of high cooling speed, low cost and high efficiency.
Description
Technical Field
The invention relates to the field of hot galvanizing production, in particular to a hot galvanizing production method for high-strength steel and ultrahigh-strength steel.
Background
In the actual production and manufacturing process of automobile parts, the steel material needs to be subjected to multiple complex processes such as stamping, welding, coating, final assembly and the like, which puts higher requirements on the formability, corrosion resistance, welding performance and surface quality of the steel material for automobiles. In the background of the process, the hot galvanizing technology is produced at the same time; the hot galvanizing is a process for combining an iron matrix and a coating by immersing the iron and steel material in molten zinc to make the surface of the iron matrix react with zinc as a main component and a small amount of other alloy elements to form an alloy layer. The hot-dip galvanized steel material has the advantages of uniform plating layer, strong adhesive force, good corrosion resistance, long service life and the like, and simultaneously improves the mechanical property of the hot-dip galvanized steel material to a certain extent.
The traditional hot galvanizing process comprises the following steps: alkali washing → acid washing → heating → soaking → rapid cooling (cooling to 450-500 ℃) → hot galvanizing → final cooling.
The quick cooling step of the hot galvanizing process generally adopts a gas injection cooling mode, and the used gas medium is a mixed gas of 5-15% of hydrogen and nitrogen; the cooling speed which can be achieved when the temperature is reduced to 400 ℃ from 800 ℃ is 30-40 ℃/s. The cooling speed of the air injection cooling mode can meet the production requirements for producing materials such as common low-carbon aluminum killed steel, IF steel, bake-hardening steel, low-alloy high-strength steel and the like. However, with the development of hot dip galvanized products, a hot dip galvanizing process for a new type of high strength steel (such as dual phase steel, multi-phase steel, martensitic steel, etc.) is a process of cooling a steel sheet to a temperature of 200 ℃ or less, then reheating the steel sheet, and then hot dip galvanizing the steel sheet.
Patent CN101348885B discloses a 1000MPa grade cold-rolled hot-galvanized dual-phase steel and a manufacturing method thereof, relating to a cold-rolled hot-galvanized dual-phase steel with the strength grade of more than 1000MPa, and the main hot-galvanized technological process comprises the following steps: the heating temperature is 780-840 ℃, the heat preservation time is 40-100 s, and the fast cooling speed is 10-20 ℃/s; the temperature of the galvanizing section is 450-470 ℃, and the galvanizing time is 5-20 s. According to the technical scheme, Cr and Mo are adopted to replace Si, so that an austenite and ferrite two-phase region is enlarged, and the hardenability of the dual-phase steel is improved. Meanwhile, the strength and toughness of the steel are improved by adding Nb and Ti refined grains, so that the steel has good weldability and usability. However, because the cooling speed of the rapid cooling section is too low, better hardenability is obtained only by the idea of adding alloy elements, so that the alloy cost of the product is greatly improved, and the market competitiveness of the product is reduced.
Patent CN110964969B discloses 'a high-strength hot-dip galvanized quenching partition steel and a production method thereof', relating to a hot-dip galvanized steel with yield strength of 600-800 MPa, tensile strength of more than or equal to 1000MPa and elongation of 18-23%, and the main hot-dip galvanized technological process comprises the following steps: a heating section: 820 +/-10 ℃; a soaking section: 820 +/-10 ℃; a slow cooling section: 710 +/-10 ℃; and (3) a rapid cooling section: 330 plus or minus 10 ℃; and (3) equalizing section: 330 plus or minus 10 ℃; induction heater/zinc pot: 460 plus or minus 5 ℃; the cooling speed requirement of the rapid cooling section is 35-45 ℃/s, the cooling speed requirement is high, and the cooling is realized by adopting an air injection cooling mode of high hydrogen atmosphere with the hydrogen content being more than or equal to 20%. However, the cooling system using high hydrogen atmosphere is required to have very high sealing performance, and additional sealing devices and various safety inspection instruments are required, which greatly increases the production cost and the danger.
Disclosure of Invention
The invention aims to solve the technical problem of providing a hot galvanizing production method for high-strength steel and ultrahigh-strength steel, which has the advantages of high cooling speed, low cost and high efficiency.
In order to achieve the purpose, the invention adopts the following technical scheme:
a hot galvanizing production method for high-strength steel and ultrahigh-strength steel comprises the following process flows: alkali washing → heating → soaking → water quenching cooling → acid washing → secondary heating → hot galvanizing → final cooling; the method specifically comprises the following steps:
(1) alkali washing: cleaning with alkali liquor to remove residues and grease on the surface of the steel plate of the high-strength steel or the ultrahigh-strength steel;
(2) heating and soaking: introducing protective gas in the heating and soaking processes;
(3) water quenching and cooling: placing the steel plate after soaking treatment into water to be rapidly cooled to room temperature; introducing protective gas in the cooling process;
(4) acid washing: cleaning an oxide film on the surface of the steel plate after water quenching and cooling by adopting a mixed solution of a sulfuric acid solution, a thiourea solution and a urotropine solution;
(5) secondary heating: carrying out secondary heating on the pickled steel plate in protective gas, wherein the heating temperature is consistent with the temperature of the hot galvanizing zinc liquid;
(6) hot galvanizing: immersing the secondarily heated steel plate into molten zinc liquid in protective gas, and carrying out hot galvanizing treatment; the temperature of the zinc liquid and the hot galvanizing time are determined according to the thickness of the steel plate;
(7) and (3) final cooling: and cooling the hot-galvanized steel plate to room temperature to complete the whole hot-galvanizing process.
The alkali liquor in the step (1) is sodium hydroxide solution.
The atmosphere of the protective gas for heating and soaking in the step (2) and water quenching and cooling in the step (3) is consistent, the atmosphere is inert gas or nitrogen, and the volume fraction content of oxygen in the protective gas is lower than 0.3%.
The mass concentration of the sulfuric acid in the mixed solution obtained in the step (4) is 10-20%, the mass concentration of thiourea is 0.05-0.1%, and the mass concentration of urotropin is 0.1-0.3%.
The protective gas atmosphere of the secondary heating in the step (5) and the hot galvanizing in the step (6) is consistent, and the protective gas atmosphere is reducing gas which is mixed gas of 80-95% of nitrogen in volume fraction and 20-5% of hydrogen in volume fraction.
In the step (6), the thickness of the steel plate is less than or equal to 1mm, the temperature of the zinc liquid is 460 +/-3 ℃, and the hot galvanizing time is 3-5 s; the thickness of the steel plate is more than 1mm and less than or equal to 2mm, the temperature of the zinc liquid is 465 +/-3 ℃, and the hot galvanizing time is 3.5-5.5 s; the thickness of the steel plate is more than 2mm, the temperature of the zinc liquid is 470 +/-3 ℃, and the hot galvanizing time is 4-6 s.
Compared with the prior art, the invention has the beneficial effects that:
1. the process method comprises an alkali washing step and an acid washing step, wherein the alkali washing step can remove grease and residues on the surface of the steel plate and can activate the surface of the steel plate; the pickling step is placed after water quenching cooling, so that an oxide film generated by water quenching cooling of the steel plate can be effectively removed, and the combination of the zinc liquid and the surface of the steel plate is facilitated;
2. by adopting a water quenching and cooling mode, the ultrahigh cooling speed of 1000-2000 ℃/s can be obtained, so that the steel grades such as high-strength and ultrahigh-strength dual-phase, multi-phase and martensitic steel can be produced by adding a small amount of alloy elements, the production cost is low, and the efficiency is high;
3. the requirement of the water quenching cooling process on air tightness is low, power consumption equipment is hardly used in the cooling process, the power consumption of a system is very low, and the economical efficiency is good; various safety detection instruments cooled by hydrogen-containing jet are not needed, and the safety detection device is safe and reliable;
4. the secondary heating is carried out in a reducing protective atmosphere containing hydrogen, so that the acid-washed high-strength steel and ultrahigh-strength steel can be further reduced, and the platability of the steel is improved;
5. in the hot galvanizing process, the zinc liquid is in a reducing protective atmosphere environment containing hydrogen, so that the surface tension of the molten zinc liquid is reduced, the infiltration capacity of the zinc liquid is improved, and the binding force of an iron base and the zinc liquid is increased;
6. the temperature of the zinc liquid and the hot galvanizing time are determined according to different thicknesses of the steel plate, so that the thickness of the galvanized layer of the steel plate after hot galvanizing can be ensured.
Drawings
FIG. 1 is a schematic view of a production process
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A hot galvanizing production process for high-strength steel and ultrahigh-strength steel comprises the following process steps:
(1) alkali washing
The cleaning agent is used for cleaning and removing residues and grease on the surface of a steel plate of high-strength steel or ultrahigh-strength steel, and the adopted solution is 10-20% of sodium hydroxide solution;
(2) heating and soaking
Heating the steel plate to 750-950 ℃ in a protective gas atmosphere; soaking at 750-950 ℃ for 1-10 min; the protective gas atmosphere is inert gas or nitrogen; the oxygen content in the protective gas is lower than 0.3 percent, so that the oxidation phenomenon generated in the heating and soaking process can be effectively prevented, the oxide layer is generated on the surface of the high-strength steel and the ultrahigh-strength steel again, and the subsequent water quenching cooling is influenced;
(3) water quenching and cooling
Placing the steel plate after soaking treatment into water for cooling, wherein the water temperature is 30-50 ℃, and rapidly cooling to room temperature at the cooling speed of 1000-2000 ℃/s; and the process needs to be carried out in a protective gas atmosphere; the protective gas is inert gas or nitrogen; the oxygen content in the protective gas is lower than 0.3 percent, so that the thickness of the oxide film on the surfaces of the high-strength steel and the ultrahigh-strength steel in the water quenching and cooling process can be effectively reduced; the water quenching and cooling can obtain ultrahigh cooling speed, so that the steel grades such as high-strength and ultrahigh-strength dual-phase, multi-phase and martensitic steel and the like can be produced by adding a small amount of alloy elements; the requirement on air tightness in the water quenching cooling process is low, various safety detection instruments cooled by hydrogen-containing jet gas are not needed, and the device is low in cost, safe and reliable;
(4) acid pickling
Acid liquor is adopted to carry out acid pickling on an oxide film generated on the surface of the steel plate in the water quenching and cooling process, the acid liquor is mixed liquor of sulfuric acid solution, thiourea solution and urotropine solution, and the mixed liquor contains 10-20% of sulfuric acid by mass, 0.05-0.1% of thiourea by mass and 0.1-0.3% of urotropine by mass; the thiourea and the urotropine are added to play a role in inhibiting corrosion and fog, prevent over-corrosion of a matrix, reduce the hydrogen absorption amount of an iron matrix and inhibit the escape of acid mist;
(5) second heating
Carrying out secondary heating on the acid-washed steel plate in a protective gas atmosphere, wherein the heating temperature is consistent with the temperature of hot galvanizing zinc liquid and is 460-470 ℃;
the protective gas atmosphere is reducing gas, and the reducing gas is a mixed gas of 80-95% by volume of nitrogen and 20-5% by volume of hydrogen; the protective gas atmosphere plays a further role in reduction and is used for reducing the acid-washed high-strength steel and the residual oxide film on the surface of the ultra-high-strength steel;
(6) hot dip galvanizing
Immersing the high-strength steel and the ultrahigh-strength steel subjected to secondary heating into molten zinc liquid in a protective gas atmosphere, and performing hot galvanizing treatment;
the thickness of the steel plate is less than or equal to 1mm, the temperature of the zinc liquid is 460 ℃, and the hot galvanizing time is 3 s;
the thickness of the steel plate is more than 1mm and less than or equal to 2mm, the temperature of the zinc liquid is 465 ℃, and the hot galvanizing time is 3.5 s;
the thickness of the steel plate is more than 2mm, the temperature of the zinc liquid is 470 ℃, and the hot galvanizing time is 4 s;
the protective gas atmosphere is reducing gas, and the reducing gas is a mixed gas of 80-95% by volume of nitrogen and 20-5% by volume of hydrogen; the protective gas atmosphere plays a role in protecting the molten zinc liquid, and the molten zinc liquid is prevented from being oxidized to form a zinc oxide film which is not beneficial to hot galvanizing;
(7) final cooling
Finally cooling the hot-galvanized high-strength steel and ultrahigh-strength steel to room temperature to complete the whole hot-galvanizing process; the final cooling can be air jet cooling or air cooling, and the final cooling is carried out to room temperature.
Example 1:
1.4mm thick quench-distributed steel (980MPa grade), hot galvanizing method:
firstly, carrying out alkaline washing on the steel plate by using a sodium hydroxide solution with the mass concentration of 15% to remove grease and residues on the surface of the steel plate; then heating to 880 ℃ in a high-purity nitrogen environment with the oxygen content of 0.05 percent, and carrying out soaking for 3 min; then, the mixture is put into water with the temperature of 40 ℃ in a high-purity nitrogen environment with the oxygen content of 0.05 percent for water quenching and cooling, and the cooling speed can reach 1200 ℃/s; pickling the water-quenched steel plate, wherein the acid solution is a mixed solution of a sulfuric acid solution, a thiourea solution and a urotropine solution, and the mixed solution has the mass concentration of 10% of sulfuric acid, 0.05% of thiourea and 0.15% of urotropine; carrying out secondary heating on the steel plate after acid washing in the mixed atmosphere protection of 90% volume fraction nitrogen and 10% volume fraction hydrogen, and heating to 465 ℃ for hot galvanizing; the temperature of the zinc liquid in the zinc pot is 465 ℃, and the zinc liquid is in a mixed atmosphere environment of nitrogen with volume fraction of 90% and hydrogen with volume fraction of 10%; the hot galvanizing time is 3.5 s; and finally cooling the hot-galvanized steel plate to room temperature in the air, thereby completing the whole hot-galvanizing process.
The performance of the obtained galvanized steel sheet is as follows: tensile strength of 1067MPa, yield strength of 812MPa, elongation of 12.5 percent and thickness of a zinc layer of 46 mu m.
Example 2
A dual phase steel (1180Mpa grade) with a thickness of 0.8mm, hot dip galvanised by the following method:
firstly, carrying out alkaline washing on a steel plate by using a sodium hydroxide solution with the mass concentration of 10% to remove grease and residues on the surface of the steel plate; then heating to 820 ℃ in a high-purity nitrogen environment with the oxygen content of 0.1%, and carrying out soaking for 5 min; then, the mixture is put into water with the temperature of 30 ℃ in a high-purity nitrogen environment with the oxygen content of 0.1 percent for water quenching and cooling, and the cooling speed can reach 1800 ℃/s; pickling the water-quenched steel plate, wherein the acid solution is a mixed solution of a sulfuric acid solution, a thiourea solution and a urotropine solution, and the mixed solution contains 15% of sulfuric acid by mass, 0.1% of thiourea by mass and 0.2% of urotropine by mass; carrying out secondary heating on the steel plate after acid washing in the mixed atmosphere protection of 85 volume percent of nitrogen and 15 volume percent of hydrogen, and heating to 460 ℃ for hot galvanizing; the temperature of the zinc liquid in the zinc pot is 460 ℃, and the zinc liquid is in a mixed atmosphere environment of nitrogen with the volume fraction of 85% and hydrogen with the volume fraction of 15%; the hot galvanizing time is 3 s; and finally cooling the hot-galvanized steel plate to room temperature in the air, thereby completing the whole hot-galvanizing process.
The performance of the obtained galvanized steel sheet is as follows: tensile strength of 1218MPa, yield strength of 927MPa, elongation of 7.8%, and thickness of zinc layer of 34 μm.
Example 3:
martensitic steel (1300MPa grade) with a thickness of 2.2mm, hot dip galvanising method as follows:
firstly, carrying out alkaline washing on a steel plate by using a sodium hydroxide solution with the mass concentration of 15% to remove grease and residues on the surface of the steel plate; then heating to 920 ℃ in a high-purity nitrogen environment with the oxygen content of 0.01 percent, and carrying out soaking for 6 min; then, the mixture is put into water with the temperature of 30 ℃ in a high-purity nitrogen environment with the oxygen content of 0.01 percent for water quenching and cooling, and the cooling speed can reach 1500 ℃/s; pickling the water-quenched steel plate, wherein the acid solution is a mixed solution of a sulfuric acid solution, a thiourea solution and a urotropine solution, and the mixed solution contains 15% by mass of sulfuric acid, 0.15% by mass of thiourea and 0.3% by mass of urotropine; carrying out secondary heating on the steel plate after acid washing in the mixed atmosphere protection of 80 volume percent of nitrogen and 20 volume percent of hydrogen, and heating to 470 ℃ for hot galvanizing; the temperature of the zinc liquid in the zinc pot is 470 ℃, and the zinc liquid is in a mixed atmosphere environment of nitrogen with the volume fraction of 80% and hydrogen with the volume fraction of 20%; the hot galvanizing time is 4 s; and finally cooling the hot-galvanized steel plate to room temperature in the air, thereby completing the whole hot-galvanizing process.
The performance of the obtained galvanized steel sheet is as follows: tensile strength 1301MPa, yield strength 1211MPa, elongation 3.8 percent and zinc layer thickness 40 μm.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (6)
1. A hot galvanizing production method for high-strength steel and ultrahigh-strength steel comprises the following process flows: alkali washing → heating → soaking → water quenching cooling → acid washing → secondary heating → hot galvanizing → final cooling; the method is characterized by specifically comprising the following steps:
(1) alkali washing: cleaning with alkali liquor to remove residues and grease on the surface of the steel plate of the high-strength steel or the ultrahigh-strength steel;
(2) heating and soaking: introducing protective gas in the heating and soaking processes;
(3) water quenching and cooling: placing the steel plate after soaking treatment into water to be rapidly cooled to room temperature; introducing protective gas in the cooling process;
(4) acid washing: cleaning an oxide film on the surface of the steel plate after water quenching and cooling by adopting a mixed solution of a sulfuric acid solution, a thiourea solution and a urotropine solution;
(5) secondary heating: carrying out secondary heating on the pickled steel plate in protective gas, wherein the heating temperature is consistent with the temperature of the hot galvanizing zinc liquid;
(6) hot galvanizing: immersing the secondarily heated steel plate into molten zinc liquid in protective gas, and carrying out hot galvanizing treatment; the temperature of the zinc liquid and the hot galvanizing time are determined according to the thickness of the steel plate;
(7) and (3) final cooling: and cooling the hot-galvanized steel plate to room temperature to complete the whole hot-galvanizing process.
2. The hot dip galvanizing production method for high-strength steel and ultrahigh-strength steel according to claim 1, characterized in that the alkali solution in the step (1) is a sodium hydroxide solution.
3. The hot dip galvanizing production method of high strength steel and ultrahigh strength steel according to claim 1, characterized in that the atmosphere of the protective gas for heating and soaking in the step (2) and water quenching and cooling in the step (3) is the same, and the protective gas is inert gas or nitrogen, and the volume fraction of oxygen in the protective gas is less than 0.3%.
4. The hot dip galvanizing production method for high-strength steel and ultrahigh-strength steel according to claim 1, wherein the mixed solution in the step (4) has a sulfuric acid mass concentration of 10-20%, a thiourea mass concentration of 0.05-0.1%, and a urotropine mass concentration of 0.1-0.3%.
5. The hot dip galvanizing production method for high-strength steel and ultrahigh-strength steel according to claim 1, characterized in that the atmosphere of the protective gas for the secondary heating in the step (5) and the hot dip galvanizing in the step (6) is consistent and is a reducing gas, and the reducing gas is a mixed gas of 80-95% by volume of nitrogen and 20-5% by volume of hydrogen.
6. The hot galvanizing production method of high-strength steel and ultrahigh-strength steel according to claim 1, characterized in that in the step (6), the thickness of the steel plate is less than or equal to 1mm, the temperature of the molten zinc is 460 ℃ +/-3 ℃, and the hot galvanizing time is 3-5 s; the thickness of the steel plate is more than 1mm and less than or equal to 2mm, the temperature of the zinc liquid is 465 +/-3 ℃, and the hot galvanizing time is 3.5-5.5 s; the thickness of the steel plate is more than 2mm, the temperature of the zinc liquid is 470 +/-3 ℃, and the hot galvanizing time is 4-6 s.
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