CN115094334A - High-strength chloride-corrosion-resistant steel bar for concrete structure and production method thereof - Google Patents
High-strength chloride-corrosion-resistant steel bar for concrete structure and production method thereof Download PDFInfo
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- CN115094334A CN115094334A CN202210857890.2A CN202210857890A CN115094334A CN 115094334 A CN115094334 A CN 115094334A CN 202210857890 A CN202210857890 A CN 202210857890A CN 115094334 A CN115094334 A CN 115094334A
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- 239000010935 stainless steel Substances 0.000 title claims abstract description 37
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 32
- 239000004567 concrete Substances 0.000 title claims abstract description 30
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 242
- 239000010959 steel Substances 0.000 claims abstract description 242
- 238000005096 rolling process Methods 0.000 claims abstract description 68
- 238000010438 heat treatment Methods 0.000 claims abstract description 38
- 238000001816 cooling Methods 0.000 claims abstract description 36
- 238000007670 refining Methods 0.000 claims abstract description 36
- 238000003723 Smelting Methods 0.000 claims abstract description 32
- 238000005266 casting Methods 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 claims abstract description 30
- 239000000463 material Substances 0.000 claims abstract description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 36
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 28
- 238000010079 rubber tapping Methods 0.000 claims description 27
- 239000000126 substance Substances 0.000 claims description 24
- 238000007664 blowing Methods 0.000 claims description 22
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 22
- 229910045601 alloy Inorganic materials 0.000 claims description 19
- 239000000956 alloy Substances 0.000 claims description 19
- 229910052757 nitrogen Inorganic materials 0.000 claims description 18
- 238000009749 continuous casting Methods 0.000 claims description 17
- 238000009628 steelmaking Methods 0.000 claims description 17
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 16
- 239000000498 cooling water Substances 0.000 claims description 16
- 239000011261 inert gas Substances 0.000 claims description 16
- 239000001301 oxygen Substances 0.000 claims description 16
- 229910052760 oxygen Inorganic materials 0.000 claims description 16
- 239000002893 slag Substances 0.000 claims description 15
- 239000002994 raw material Substances 0.000 claims description 13
- 239000003795 chemical substances by application Substances 0.000 claims description 12
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 8
- 229910002467 CrFe Inorganic materials 0.000 claims description 8
- 229910001208 Crucible steel Inorganic materials 0.000 claims description 8
- 229910005347 FeSi Inorganic materials 0.000 claims description 8
- 229910004534 SiMn Inorganic materials 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 7
- 229910052786 argon Inorganic materials 0.000 claims description 4
- 229910052698 phosphorus Inorganic materials 0.000 claims description 4
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 3
- 230000002787 reinforcement Effects 0.000 claims 7
- 229910001341 Crude steel Inorganic materials 0.000 claims 1
- 238000005260 corrosion Methods 0.000 abstract description 47
- 230000007797 corrosion Effects 0.000 abstract description 46
- 238000010276 construction Methods 0.000 abstract description 3
- 238000012545 processing Methods 0.000 abstract description 2
- 239000011651 chromium Substances 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 13
- 238000009847 ladle furnace Methods 0.000 description 11
- 238000005728 strengthening Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 150000001804 chlorine Chemical class 0.000 description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 6
- 235000011941 Tilia x europaea Nutrition 0.000 description 6
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 6
- 239000000292 calcium oxide Substances 0.000 description 6
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 6
- 239000004571 lime Substances 0.000 description 6
- 239000006104 solid solution Substances 0.000 description 6
- 230000001502 supplementing effect Effects 0.000 description 6
- 230000001681 protective effect Effects 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 229910001563 bainite Inorganic materials 0.000 description 4
- 238000005536 corrosion prevention Methods 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- CXOWYMLTGOFURZ-UHFFFAOYSA-N azanylidynechromium Chemical compound [Cr]#N CXOWYMLTGOFURZ-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000010485 coping Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000004574 high-performance concrete Substances 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 230000009545 invasion Effects 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 239000011150 reinforced concrete Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 239000012085 test solution Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 230000003442 weekly effect Effects 0.000 description 1
Classifications
-
- 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
-
- 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
- B21B1/16—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 wire rods, bars, merchant bars, rounds wire or material of like small cross-section
- B21B1/163—Rolling or cold-forming of concrete reinforcement bars or wire ; Rolls therefor
-
- 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
-
- 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
-
- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
-
- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/08—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires for concrete reinforcement
-
- 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
- C22C33/06—Making ferrous alloys by melting using master alloys
-
- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
-
- 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
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- 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
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
-
- 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
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/01—Reinforcing elements of metal, e.g. with non-structural coatings
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Architecture (AREA)
- Manufacturing & Machinery (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention belongs to the field of processing of steel bars, and particularly relates to a high-strength chloride-corrosion-resistant steel bar for a concrete structure and a production method thereof. The production method of the steel bar comprises the following steps: s1, smelting in a converter; s2, refining in an LF furnace; s3, continuously casting small square billets; s4, heating by a heating furnace; and S5, rolling and cooling the bar material. According to the invention, through the optimized proportion of each component and the combination of the controlled rolling and controlled cooling process, the strength grade of the prepared steel bar reaches the technical requirement of 635MPa grade, the corrosion resistance is 1 time or more of that of the HRB400 common steel bar, and the requirements of the construction of key concrete engineering in China can be met.
Description
Technical Field
The invention belongs to the field of steel bar processing, and particularly relates to a high-strength chlorine salt corrosion-resistant steel bar for a concrete structure and a production method thereof.
Background
At present, a large number of reinforced concrete structures in China are applied to environments taking chlorine salt as a main corrosion medium, such as natural chlorine salt corrosion environments of marine reefs, saline-alkali land and the like, and artificial chlorine salt corrosion environments of roads, bridges and the like spreading ice salt. In order to solve the problem of steel bar corrosion in a concrete structure, corrosion prevention technologies such as a steel bar rust inhibitor, a coated steel bar, high-performance concrete, a concrete surface coating, a cathode protection method and the like are developed at home and abroad, and although the corrosion prevention technology plays a role in delaying the corrosion of the steel bar to a certain extent, the corrosion prevention technology has the problems of uncertain corrosion prevention effect, difficult construction, high cost and the like; the stainless steel bar has a corrosion resistant alloy Cr content of more than 12% and a total Cr + Ni content of about 20%, so that the production process is complex and the production cost is high, thereby limiting the application of a large amount.
The patent document of Chinese patent publication No. CN201810399267.0 discloses a high-strength corrosion-resistant ferrite/bainite dual-phase steel bar for a marine concrete structure and a preparation method thereof, wherein the steel bar has a ferrite/bainite dual-phase microstructure, wherein bainite accounts for 50-60%, and the steel bar comprises the following chemical components in percentage by weight: c: 0.015% -0.020%, Si: 0.45-0.55%, Mn: 1.1-1.5%, Cr: 10.5% -11.2%, Ni: 1.0% -1.5%, Mo: 0.8% -0.95%, V: 0.03 to 0.06 percent. The steel bar has excellent marine chloride ion corrosion resistance and high corrosion resistance, can be used for a long service life in a concrete structure in a severe marine corrosion environment, but the elongation performance of the steel bar is influenced by more bainite content, so that the steel bar is not suitable for popularization and application in engineering.
Chinese patent publication No. CN201710954676.8 discloses a 'production method of 500 MPa-level ribbed stainless steel bars for ocean building structures', the yield strength of the prepared stainless steel bars is more than 500MPa, the PREN value ranges from 32 to 35, the chloride ion corrosion resistance is strong, and the yield ratio is more than or equal to 1.2. The stainless steel bar obtained by adopting 2205 steel billets through processes of coping, heating, rolling, online solid solution, acid pickling passivation and the like in sequence has excellent corrosion resistance, meets the steel requirements of ocean engineering structures, but has complex production process, and most domestic steel mills do not have production equipment for online solid solution, acid pickling passivation and the like, and are not favorable for batch popularization and application.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, adopts the design of adding Ti and Mn and provides a production method of a high-strength chloride corrosion resistant steel bar for a concrete structure.
The invention aims to solve another technical problem and provide a high-strength chloride-corrosion-resistant reinforcing steel bar for a concrete structure, which overcomes the defects in the prior art and has the yield strength R eL More than or equal to 635MPa, tensile strength R m The steel bar has the advantages that the steel bar is not less than 795MPa, the elongation A after fracture is not less than 15%, and the requirement of the market on 635 MPa-grade steel bars is met.
In order to solve the technical problem, the technical scheme is that the production method of the high-strength chloride corrosion resistant steel bar for the concrete structure comprises the following steps:
s1, smelting in a converter: smelting steelmaking raw materials into crude molten steel, blowing by using a top-blowing oxygen lance, finishing smelting when the weight content of C in the crude molten steel is more than or equal to 0.06 percent, the weight content of P and S is less than or equal to 0.020 percent and the temperature is 1640-;
s2, refining in an LF furnace: the method comprises the following steps that a steel ladle enters a refining furnace, bottom blowing inert gas is started in the refining furnace, so that molten steel can be blown, but the molten steel cannot be sprayed out of the steel ladle, then the flow of the inert gas is reduced, an electrode is started to heat and raise the temperature, a slag making material is added to make white slag, when the oxygen content is less than or equal to 25ppm, a Ti wire is added, then a nitrogen increasing agent is added, chemical components are detected before the steel ladle is taken out of a station, carbon powder and alloy are supplemented according to a detection result, and refining is stopped when the components of the molten steel reach a set target and the temperature of the molten steel reaches 1550-;
s3, continuous casting of small square billets: hoisting the ladle to a continuous casting platform, casting the ladle into a steel billet, wherein the ladle adopts whole-process protective casting in the casting process, and the primary cooling water flow is 110- 3 H, continuously casting the secondary cooling water with the specific water amount of 0.9-1.3L/kg into qualified billets;
s4, heating by a heating furnace: the cast steel billet enters a heating furnace, is heated to 1120-1220 ℃ in the heating furnace, and is rolled into the steel bar with the required specification;
s5, controlled rolling and controlled cooling rolling of the bar: cooling a steel billet for rolling the steel bar to 1020-1080 ℃, then rolling, carrying out rough rolling, intermediate rolling and final rolling, then rolling to the required specification, and cooling by controlling after the final rolling, wherein the temperature of an upper cooling bed is 880-930 ℃ to obtain the chlorine salt corrosion resistant steel bar.
Preferably, the chemical components of the steel billet in the step S3 are as follows by weight: c: 0.20-0.30%; si: 0.40-0.60%; mn: 1.20-1.60%; p: less than or equal to 0.030 percent; s: less than or equal to 0.030 percent; ti: 0.010-0.030%; nb: 0.030-0.050%; cr: 1.2-2.0%; n: 0.008% -0.012%; the balance of Fe and inevitable impurity elements.
Preferably, the content of each component in the set composition of molten steel in step S2 meets the requirements of Ti/C ≥ 0.03, Mn/S ≥ 40, and Cr/N ≥ 100.
Preferably, in step S1, the apparatus for smelting steel-making raw materials into crude molten steel is a converter, the steel-making raw materials include scrap steel and molten iron, and the adding sequence is as follows: firstly, charging scrap steel into a steelmaking furnace, then pouring molten iron, wherein the weight ratio of the scrap steel to the molten iron is 1: 4.
Preferably, the step S1 includes adding deoxidizer and alloy at the time of tapping 1/3, in the following order: deoxidizer → FeSi → SiMn → CrFe → NbFe → deoxidizer, when tapping 3/4, add aluminum cake to further deoxidize.
Preferably, the refining furnace in the step S2 is an LF furnace, and the ladle in the step S2 is bottom-blown with argon throughout the process, and the flow of argon is adjusted to homogenize the molten steel components and to float and remove inclusions.
Preferably, the nitrogen content in the nitrogen increasing agent is 28% -32%.
Preferably, the section of the casting blank in the step S3 is 140-170mm 2 。
In order to solve another technical problem, the invention adopts the technical scheme that the high-strength chloride corrosion resistant steel bar for the concrete structure is prepared by any one of the preparation methods.
The invention has the advantages that:
(1) according to the invention, through the optimized proportion of each component and the combination of the controlled rolling and controlled cooling process, the strength grade of the prepared steel bar reaches the technical requirement of 635MPa grade, and the corrosion resistance is 1 time or more than that of HRB400 common steel bar, so that the requirement of the construction of key concrete engineering in China can be met; in addition, the production cost of the steel bar is low, the production process is feasible, large-scale production and popularization and application are facilitated, and the market prospect is good.
(2) The effect of the alloy elements in the invention is as follows:
c: c is an important and cheap strengthening element, can obviously improve the strength of the steel, but can reduce the corrosion resistance of Cr along with the increase of the content of C, so the content of C is controlled to be 0.20-0.30 percent in the invention.
Si: the method is favorable for improving the pitting corrosion resistance of the steel, but can also reduce the ductility index of the steel, and the Si content is controlled to be 0.40-0.60 percent.
Mn: the hot brittleness caused by S in the steel can be improved, but the steel bar can form martensite when the content is higher, so that the toughness of the steel bar is influenced, and the Mn content is controlled to be 1.20-1.60 percent in the invention.
P: has certain advantage on atmospheric corrosion resistance, but has no obvious effect on chlorine salt corrosion resistance, and the P content is controlled to be less than or equal to 0.030 percent.
S: is a harmful element, but because certain Mn is added in the invention, the S content is controlled to be less than or equal to 0.030 percent.
Ti: the precipitation of the Ti carbonitride plays roles of precipitation strengthening and fine grain strengthening, and simultaneously reduces the influence of C on Cr corrosion resistance, and the Ti content is controlled to be 0.010-0.030 percent.
Nb: second phase particles such as NbN, NbC and the like are generated in the steel to play a role in fine grain strengthening, the strength index is improved on the premise of not reducing the ductility index, and meanwhile, the corrosion resistance is favorably ensured, the Nb content in the general steel is preferably controlled within 0.05 percent, the strengthening effect is not obvious when the Nb content exceeds 0.05 percent, and the production cost is increased, so the Nb content is controlled to be 0.030-0.050 percent.
Cr: cr is an important element for improving the corrosion resistance of steel, and can form a layer of compact, uniform and complete protective film on the surface of the steel, effectively prevent the invasion of chloride ions and greatly improve the corrosion resistance of the steel bar in a concrete structure, wherein the content of Cr is controlled to be 1.2-2.0 percent.
N: n mainly forms fine second phase particles with Nb in the steel, so that the toughness of the steel is improved, and the corrosion resistance of the steel is improved. However, excessive N causes aging, resulting in a great increase in strength and a great decrease in ductility. The content of N in the invention is controlled to be 0.008% -0.012%.
According to the range of the components, the steel grade of the invention can be produced into the high-strength chloride corrosion resistant steel bar by adopting converter smelting, LF furnace refining, billet continuous casting, heating furnace heating and bar controlled rolling and controlled cooling rolling, and the mechanical properties of the steel bar can reach: the yield strength ReL is more than or equal to 635MPa, the tensile strength Rm is more than or equal to 795MPa, and the elongation A after fracture is more than or equal to 15 percent.
(3) The invention adopts the component design of C and Ti and ensures a certain Ti/C ratio, on one hand, the solid solution strengthening effect of cheap C is exerted, and the TiC can be formed by the certain Ti/C ratio, so that the precipitation is further strengthened, the carbide of Cr is avoided being formed, the solid solution quantity of Cr is improved, and the corrosion resistance is ensured; and the cost is reduced, thereby being beneficial to the popularization and the application of the invention.
(4) The invention adopts the component design of adding Mn and ensures a certain Mn/S ratio to control the precipitation of S in the crystal boundary during the crystallization, thereby reducing the hot brittleness sensitivity of the billet during the hot rolling, improving the corrosion resistance and simultaneously reducing the production cost of desulfurization; a proper amount of Nb microalloying elements are added, and the strength index is improved on the premise of not reducing the ductility index by using the effects of fine grain strengthening and solid solution strengthening; proper amount of Cr is added, the Cr/N ratio is ensured, cheap N is utilized to form a chromium nitride film, the corrosion resistance is improved, and meanwhile, expensive corrosion resistant alloy elements such as Ni, Mo and the like are reduced or not added, and the production cost is reduced.
(5) The rolling and cooling control process is adopted, the combination effect of each element is fully exerted, and the strength and the corrosion resistance are improved; the billet steel adopts higher heating temperature to promote the solid solution of Nb element, exerts the fine crystal strengthening effect, and adopts slower cooling speed after rolling, thereby avoiding the generation of a large amount of martensite structures and ensuring the toughness of the steel; meanwhile, the key point of the invention is that the components are combined and optimized, and are organically combined with the quality control of steel making and rolling, so that the high strength and toughness performance is obtained, and the excellent chlorine salt corrosion resistance is obtained.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following combinations and examples, and all other embodiments obtained by a person of ordinary skill in the art based on the examples of the present invention without any creative effort belong to the protection scope of the present invention.
Example 1
The embodiment provides a production method of a high-strength chloride corrosion resistant steel bar for a concrete structure, which comprises the following steps:
the steel comprises the following chemical components in parts by weight: c: 0.20 percent; si: 0.60 percent; mn: 1.20 percent; p: 0.020%; s: 0.030%; ti: 0.030 percent; nb: 0.050%; cr: 1.2 percent; n: 0.012%; the balance of Fe and inevitable impurity elements; Ti/C is 0.15, Mn/S is 40, Cr/N is 100;
s1, smelting in a converter: smelting steelmaking raw materials into crude molten steel, adopting a top blowing oxygen lance to blow, finishing smelting when the weight content of C in the crude molten steel is 0.06%, the weight content of P and S is 0.020% and the temperature is 1640 ℃, tapping the crude molten steel, adding a deoxidizing agent and an alloy when tapping 1/3 in the tapping process, wherein the addition amount meets the requirement of chemical components of a steel billet (if the addition amount is too much, the steel is returned to the furnace for smelting), and the adding sequence is as follows: deoxidizer → FeSi → SiMn → CrFe → NbFe → deoxidizer, when tapping 3/4, add aluminum cake to further deoxidize;
s2, refining in an LF (ladle furnace): the method comprises the following steps of (1) enabling a steel ladle to enter a refining furnace, starting bottom blowing inert gas in the refining furnace to enable molten steel to be blown, but enabling the molten steel not to be sprayed out of the steel ladle, then reducing the flow rate of the inert gas, starting an electrode to heat and raise the temperature, adding a slag making material to make white slag (calcium oxide, derived from lime), adding a Ti wire when the oxygen content is 20ppm, then adding a nitrogen increasing agent (the nitrogen content is 28% -32%, and 0.4kg is added in each ton of steel), detecting chemical components before leaving a station, supplementing carbon powder and alloy according to a detection result, and stopping refining when the components of the molten steel reach a set target and the temperature of the molten steel reaches 1550 ℃;
s3, continuous casting of small square billets: hoisting the steel ladle to a continuous casting platform, casting the steel ladle into a steel billet, wherein the steel ladle adopts whole-process protective casting in the casting process, and the primary cooling water flow is 110m 3 And h, continuously casting the secondary cooling water with the specific water amount of 1.3L/kg into qualified billets.
S4, heating by a heating furnace: the cast steel billet enters a heating furnace, is heated to 1220 ℃ in the heating furnace and is rolled into the steel bar with the required specification;
s5, controlled rolling and controlled cooling rolling of the bar: and cooling the rolled steel bar to 1080 ℃, then rolling, rolling to the required specification after rough rolling, intermediate rolling and final rolling, and cooling by controlling after final rolling at the temperature of 930 ℃ on a cooling bed to obtain the chloride corrosion resistant steel bar 1.
Example 2
The embodiment provides a production method of a high-strength chloride corrosion resistant steel bar for a concrete structure, which comprises the following steps:
the steel comprises the following chemical components in parts by weight: c: 0.25 percent; si: 0.50 percent; mn: 1.40 percent; p: 0.025%; s: 0.025 percent; ti: 0.020%; nb: 0.040%; cr: 1.6 percent; n: 0.010%; the balance of Fe and inevitable impurity elements; Ti/C-0.08, Mn/S-56, Cr/N-160;
s1, smelting in a converter: smelting a steelmaking raw material into crude molten steel, blowing by using a top-blowing oxygen lance, finishing smelting when the weight content of C in the crude molten steel is 0.09%, the weight content of P is 0.015%, the weight content of S is 0.017%, and the temperature is 1644 ℃, tapping the crude molten steel, adding a deoxidizer and an alloy when tapping 1/3 in the tapping process, wherein the addition amount meets the requirement of chemical components of a steel billet (re-melting if the addition amount is too much), and the addition sequence is as follows: deoxidizer → FeSi → SiMn → CrFe → NbFe → deoxidizer, when tapping 3/4, add aluminum cake to further deoxidize;
s2, refining in an LF furnace: the method comprises the following steps of (1) enabling a steel ladle to enter a refining furnace, starting bottom blowing inert gas for the steel ladle of the refining furnace to enable molten steel to be blown, but the molten steel cannot be sprayed out of the steel ladle, then reducing the flow of the inert gas, starting an electrode to heat and raise the temperature, adding a slag making material to make white slag (calcium oxide, which is derived from lime), adding a Ti wire when the oxygen content is 15ppm, then adding a nitrogen increasing agent (the nitrogen content is 28% -32%, and 0.4kg is added in each ton of steel), checking chemical components before leaving the station, supplementing carbon powder and alloy according to the checking result, and stopping refining when the molten steel components reach a set target and the molten steel temperature reaches 1553 ℃;
s3, continuous casting of small square billets: hoisting the steel ladle to a continuous casting platform, casting the steel ladle into a steel billet, wherein the steel ladle adopts whole-process protective casting in the casting process, and the primary cooling water flow is 130m 3 And h, the secondary cooling water ratio is 0.9L/kg, and the steel billet is continuously cast into a qualified steel billet.
S4, heating by a heating furnace: the cast steel billet enters a heating furnace, is heated to 1120 ℃ in the heating furnace and is rolled into the steel bar with the required specification;
s5, controlled rolling and controlled cooling rolling of the bar: and cooling the steel billet for the rolled steel bar to 1030 ℃, then rolling the steel billet for the rolled steel bar into the required specification after rough rolling, intermediate rolling and final rolling, and cooling the steel billet for the final rolling by controlling the temperature of an upper cooling bed to 880 ℃ to obtain the chloride corrosion resistant steel bar 2.
Example 3
The embodiment provides a production method of a high-strength chloride corrosion resistant steel bar for a concrete structure, which comprises the following steps:
the steel comprises the following chemical components in parts by weight: c: 0.30 percent; si: 0.40 percent; mn: 1.60 percent; p: 0.030%; s: 0.020%; ti: 0.010%; nb: 0.030 percent; cr: 2.0 percent; n: 0.008 percent; the balance of Fe and inevitable impurity elements; Ti/C0.03, Mn/S80, Cr/N250;
s1, smelting in a converter: smelting a steelmaking raw material into crude molten steel, blowing by using a top-blowing oxygen lance, finishing smelting when the weight content of C in the crude molten steel is 0.08%, the weight content of P is 0.014%, the weight content of S is 0.012%, and the temperature is 1648 ℃, tapping the crude molten steel, adding a deoxidizer and an alloy when tapping 1/3 in the tapping process, wherein the addition amount meets the requirement of chemical components of a billet (re-melting if the addition amount is too much), and the addition sequence is as follows: deoxidizer → FeSi → SiMn → CrFe → NbFe → deoxidizer, when tapping 3/4, add aluminum cake to further deoxidize;
s2, refining in an LF furnace: the method comprises the following steps of (1) enabling a steel ladle to enter a refining furnace, starting bottom blowing inert gas for the steel ladle of the refining furnace to enable molten steel to be blown, but the molten steel cannot be sprayed out of the steel ladle, then reducing the flow of the inert gas, starting an electrode to heat and raise the temperature, adding a slag making material to make white slag (calcium oxide, which is derived from lime), adding a Ti wire when the oxygen content is 16ppm, then adding a nitrogen increasing agent (the nitrogen content is 28% -32%, and 0.4kg is added in each ton of steel), checking chemical components before leaving the station, supplementing carbon powder and alloy according to the checking result, and stopping refining when the molten steel components reach a set target and the molten steel temperature reaches 1558 ℃;
s3, continuous casting of small square billets: hoisting the steel ladle to a continuous casting platform, casting the steel ladle into a steel billet, wherein the steel ladle adopts full-process protection casting in the casting process, and the primary cooling water flow is 115m 3 And h, the secondary cooling water ratio is 1.2L/kg, and the steel billet is continuously cast into a qualified steel billet.
S4, heating by a heating furnace: the cast steel billet enters a heating furnace, is heated to 1180 ℃ in the heating furnace and is rolled into the steel bar with the required specification;
s5, controlled rolling and controlled cooling rolling of the bar: and (3) cooling the steel billet for rolling the steel bar to 1050 ℃, then rolling the steel billet for rolling into the required specification after rough rolling, intermediate rolling and final rolling, and cooling the steel billet for rolling after final rolling by controlling the temperature of an upper cooling bed to be 920 ℃ to obtain the chloride corrosion resistant steel bar 3.
Example 4
The embodiment provides a production method of a high-strength chloride corrosion resistant steel bar for a concrete structure, which comprises the following steps:
the steel comprises the following chemical components in parts by weight: c: 0.22 percent; si: 0.55 percent; mn: 1.30 percent; p: 0.021%; s: 0.028%; ti: 0.026%; nb: 0.045%; cr: 1.4 percent; n: 0.011 percent; the balance of Fe and inevitable impurity elements; Ti/C is 0.12, Mn/S is 46, Cr/N is 127;
s1, smelting in a converter: smelting a steelmaking raw material into crude molten steel, blowing by using a top-blowing oxygen lance, finishing smelting when the weight content of C in the crude molten steel is 0.07%, the weight content of P is 0.018%, the weight content of S is 0.015%, and the temperature is 1653 ℃, tapping the crude molten steel, adding a deoxidizer and an alloy when tapping 1/3 in the tapping process, wherein the addition amount meets the requirement of chemical components of a steel billet (if the addition amount is too much, the steel is returned to the furnace for smelting again), and the addition sequence is as follows: deoxidizer → FeSi → SiMn → CrFe → NbFe → deoxidizer, when tapping 3/4, add aluminum cake to further deoxidize;
s2, refining in an LF furnace: the method comprises the following steps of (1) enabling a steel ladle to enter a refining furnace, starting bottom blowing inert gas for the steel ladle of the refining furnace to enable molten steel to be blown, but the molten steel cannot be sprayed out of the steel ladle, then reducing the flow of the inert gas, starting an electrode to heat and raise the temperature, adding a slag making material to make white slag (calcium oxide, which is derived from lime), adding a Ti wire when the oxygen content is 10ppm, then adding a nitrogen increasing agent (the nitrogen content is 28% -32%, and 0.4kg is added in each ton of steel), checking chemical components before leaving the station, supplementing carbon powder and alloy according to the checking result, and stopping refining when the molten steel components reach a set target and the molten steel temperature reaches 1562 ℃;
s3, continuous casting of small square billets: hoisting the steel ladle to a continuous casting platform, casting the steel ladle into a steel billet, wherein the steel ladle adopts whole-process protective casting in the casting process, and the primary cooling water flow is 110m 3 And h, the secondary cooling water ratio is 1.1L/kg, and the steel billet is continuously cast into a qualified steel billet.
S4, heating by a heating furnace: the cast steel billet enters a heating furnace, is heated to 1200 ℃ in the heating furnace and is rolled into the steel bar with the required specification;
s5, controlled rolling and controlled cooling rolling of the bar: and cooling the steel billet for the rolled steel bar to 1060 ℃, then rolling the steel billet for the rolled steel bar to the required specification after rough rolling, intermediate rolling and final rolling, and cooling the steel billet for the rolled steel bar by controlling the temperature of an upper cooling bed to 900 ℃ after the final rolling to obtain the chloride corrosion resistant steel bar 4.
Example 5
The embodiment provides a production method of a high-strength chloride corrosion resistant steel bar for a concrete structure, which comprises the following steps:
the steel comprises the following chemical components in parts by weight: c: 0.26 percent; si: 0.48 percent; mn: 1.48 percent; p: 0.018%; s: 0.022%; ti: 0.021%; nb: 0.041 percent; cr: 1.7 percent; n: 0.009%; the balance of Fe and inevitable impurity elements; Ti/C0.08, Mn/S67, Cr/N189;
s1, smelting in a converter: smelting steelmaking raw materials into crude molten steel, blowing by using a top blowing oxygen lance, finishing smelting when the weight content of C in the crude molten steel is 0.09%, the weight content of P is 0.019%, the weight content of S is 0.016% and the temperature is 1656 ℃, tapping the crude molten steel, adding a deoxidizer and an alloy when tapping 1/3 in the tapping process, wherein the adding amount meets the requirement of chemical components of a steel billet (if the adding amount is too much, returning to the furnace for smelting again), and the adding sequence is as follows: deoxidizer → FeSi → SiMn → CrFe → NbFe → deoxidizer, when tapping 3/4, add aluminum cake to further deoxidize;
s2, refining in an LF (ladle furnace): the method comprises the following steps of (1) enabling a steel ladle to enter a refining furnace, starting bottom blowing inert gas for the steel ladle of the refining furnace to enable molten steel to be blown, but the molten steel cannot be sprayed out of the steel ladle, then reducing the flow of the inert gas, starting an electrode to heat and raise the temperature, adding a slag making material to make white slag (calcium oxide, which is derived from lime), adding a Ti wire when the oxygen content is 13ppm, then adding a nitrogen increasing agent (the nitrogen content is 28% -32%, and 0.4kg is added in each ton of steel), checking chemical components before leaving the station, supplementing carbon powder and alloy according to the checking result, and stopping refining when the molten steel components reach a set target and the molten steel temperature reaches 1567 ℃;
s3, continuous casting of small square billets: hoisting and conveying the steel ladle to a continuous casting platform, casting the steel ladle into a steel billet, wherein the steel ladle adopts full-process protection casting in the casting process, and the primary cooling water flow is 120m 3 And h, the secondary cooling water ratio is 1.2L/kg, and the steel billet is continuously cast into a qualified steel billet.
S4, heating by a heating furnace: the cast steel billet enters a heating furnace, is heated to 1160 ℃ in the heating furnace and is rolled into the steel bar with the required specification;
s5, controlled rolling and controlled cooling rolling of the bar: and cooling the rolled steel bar to 1040 ℃ by using a steel billet, then rolling the steel bar to the required specification after rough rolling, intermediate rolling and final rolling, and cooling the steel bar by controlling the temperature of an upper cooling bed to 910 ℃ after the final rolling to obtain the chloride corrosion resistant steel bar 5.
Example 6
The embodiment provides a production method of a high-strength chloride corrosion resistant steel bar for a concrete structure, which comprises the following steps:
the steel comprises the following chemical components in parts by weight: c: 0.28 percent; si: 0.44%; mn: 1.55 percent; p: 0.026%; s: 0.024%; ti: 0.015 percent; nb: 0.034%; cr: 1.9 percent; n: 0.010%; the balance of Fe and inevitable impurity elements; Ti/C is 0.05, Mn/S is 65, Cr/N is 190;
s1, smelting in a converter: smelting steelmaking raw materials into crude molten steel, adopting a top blowing oxygen lance to blow, finishing smelting when the weight content of C in the crude molten steel is 0.08%, the weight content of P and S is 0.017% and the temperature is 1660 ℃, tapping the crude molten steel, adding a deoxidizing agent and an alloy when tapping 1/3 in the tapping process, wherein the addition amount meets the requirement of chemical components of a steel billet (if the addition amount is too much, the steel is returned to the furnace for smelting), and the adding sequence is as follows: deoxidizer → FeSi → SiMn → CrFe → NbFe → deoxidizer, when tapping 3/4, add aluminum cake to further deoxidize;
s2, refining in an LF furnace: the method comprises the following steps of (1) enabling a steel ladle to enter a refining furnace, starting bottom blowing inert gas for the steel ladle of the refining furnace to enable molten steel to be blown, but enabling the molten steel not to be sprayed out of the steel ladle, then reducing the flow rate of the inert gas, starting an electrode to heat and raise the temperature, adding a slagging material to make white slag (calcium oxide, derived from lime), adding a Ti wire when the oxygen content is 11ppm, then adding a nitrogen increasing agent (the nitrogen content is 28% -32%, and 0.4kg is added in each ton of steel), checking chemical components before leaving a station, supplementing carbon powder and alloy according to a checking result, and stopping refining when the components of the molten steel reach a set target and the temperature of the molten steel reaches 1570 ℃;
s3, continuous casting of small square billets: hoisting the steel ladle to a continuous casting platform, casting the steel ladle into a steel billet, wherein the steel ladle adopts full-process protection casting in the casting process, and the primary cooling water flow is 125m 3 And h, continuously casting the secondary cooling water with the specific water amount of 1.3L/kg into qualified billets.
S4, heating by a heating furnace: the cast steel billet enters a heating furnace, is heated to 1150 ℃ in the heating furnace and is rolled into the steel bar with the required specification;
s5, controlled rolling and controlled cooling rolling of the bar: and cooling the rolled steel bar to 1030 ℃ by using a steel billet, then rolling the steel bar to the required specification after rough rolling, intermediate rolling and final rolling, and cooling the steel bar after the final rolling by controlling the temperature of an upper cooling bed to 905 ℃ to obtain the chloride corrosion resistant steel bar 6.
In the above examples 1 to 6, the steel-making raw materials were scrap steel and molten iron, and the weight ratio of the scrap steel to the molten iron was 1: 4, and any scrap steel may be used.
Comparative example 1
HRB400 steel bars were selected as comparative examples.
The melting chemistry of inventive examples 1-6 and comparative example 1 are shown in table 1.
TABLE 1 melting chemical composition (%)
| Examples | C | Si | Mn | P | S | Cr | Ti | Nb | N | Ti/C | Mn/S | Cr/N |
| 1 | 0.20 | 0.60 | 1.20 | 0.020 | 0.030 | 1.2 | 0.030 | 0.050 | 0.012 | 0.15 | 40 | 100 |
| 2 | 0.25 | 0.50 | 1.40 | 0.025 | 0.025 | 1.6 | 0.020 | 0.040 | 0.010 | 0.08 | 56 | 160 |
| 3 | 0.30 | 0.40 | 1.60 | 0.030 | 0.020 | 2.0 | 0.010 | 0.030 | 0.008 | 0.03 | 80 | 250 |
| 4 | 0.22 | 0.55 | 1.30 | 0.021 | 0.028 | 1.4 | 0.026 | 0.045 | 0.011 | 0.12 | 46 | 127 |
| 5 | 0.26 | 0.48 | 1.48 | 0.018 | 0.022 | 1.7 | 0.021 | 0.041 | 0.009 | 0.08 | 67 | 189 |
| 6 | 0.28 | 0.44 | 1.55 | 0.026 | 0.024 | 1.9 | 0.015 | 0.034 | 0.010 | 0.05 | 65 | 190 |
| Comparative example 1 | 0.23 | 0.45 | 1.42 | 0.027 | 0.021 | / | / | 0.035 | 0.006 | / | 69 | / |
The steelmaking process of inventive examples 1-6 and comparative example 1 is shown in Table 2.
TABLE 2 steelmaking Process of the examples
The steel rolling processes of examples 1 to 6 of the present invention and comparative example 1 are shown in Table 3.
TABLE 3 Steel Rolling Process of examples
The mechanical properties of the steel bars prepared in examples 1 to 6 of the present invention and the steel bar of comparative example 1 are shown in table 4. The mechanical property of the steel bar is tested according to GB/T28900, wherein: r is eL The yield strength; r m Is the tensile strength; and A is the elongation after fracture (d is the nominal diameter of the steel bar) under the gauge length of 5 d.
TABLE 4 mechanical properties of the examples
| Examples | R eL (MPa) | R m (MPa) | A(％) |
| 1 | 670 | 845 | 17 |
| 2 | 675 | 840 | 18 |
| 3 | 660 | 840 | 18 |
| 4 | 665 | 835 | 17 |
| 5 | 660 | 835 | 19 |
| 6 | 665 | 840 | 18 |
| Comparative example 1 | 475 | 660 | 19 |
As can be seen from Table 4 above, the yield strengths R of the reinforcing bars obtained in examples 1 to 6 eL Greater than 660MPa, meets the market requirement on 635 MPa-grade steel bars, and the yield strength R of the steel bars prepared in the comparative example 1 (namely the common HRB400 steel bar) eL 470MPa, and can only reach 400MPa level.
The corrosion resistance of inventive examples 1 to 6 and comparative example 1 are shown in Table 5 (the corrosion resistance was evaluated by the immersion corrosion test).
The test solution of the weekly immersion corrosion test is 3.5 percent NaCl solution, the temperature of the solution is 35 +/-2 ℃, the drying temperature is 45 +/-2 ℃, and the humidity is 30 +/-2 ℃. The cycle time is 60 + -5 min, wherein the soaking time is 12 + -2 deg.C, and the exposure time is 48 + -2 deg.C. The test period is as follows: 2. 3, 7 and 10 days; parallel sets of 6 samples were taken during each cycle.
The relative corrosion rate of the corrosion-resistant steel bar is 45.04-49.79%, and the corrosion resistance of the corrosion-resistant steel bar is 1 time or more than that of the common HRB400 steel bar.
The relative corrosion rate is the corrosion rate of the corrosion-resistant steel bar/the corrosion rate of the comparative steel bar (HRB400) × 100%.
TABLE 5 Corrosion resistance of the examples
As can be seen from Table 5, the corrosion rates of the steel bars prepared in examples 1-6 are less than 2.65g/m when the test period of the corrosion resistance of the steel bars prepared in examples 1-6 reaches 10 days 2 H; comparative example 1 (i.e., a conventional HRB400 steel bar) has a corrosion rate of 5.44g/m from the test period of the corrosion resistance to 10 days 2 H, therefore, the corrosion rate of the steel bar prepared by the method is far less than that of the common HRB400 steel bar; meanwhile, compared with the comparative example 1, the relative corrosion rate of the steel bar is less than or equal to 50%, and the corrosion resistance is improved by 1 time or more.
The invention is not to be considered as limited to the specific embodiments shown and described, but is to be understood to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A production method of a high-strength chloride corrosion-resistant steel bar for a concrete structure is characterized by comprising the following steps:
s1, smelting in a converter: smelting steelmaking raw materials into crude molten steel, blowing by using a top-blowing oxygen lance, finishing smelting when the weight content of C in the crude molten steel is more than or equal to 0.06 percent, the weight content of P and S is less than or equal to 0.020 percent and the temperature is 1640-;
s2, refining in an LF furnace: the method comprises the following steps that a steel ladle enters a refining furnace, bottom blowing inert gas is started in the refining furnace, so that molten steel can be blown, but the molten steel cannot be sprayed out of the steel ladle, then the flow of the inert gas is reduced, an electrode is started to heat and raise the temperature, a slag making material is added to make white slag, when the oxygen content is less than or equal to 25ppm, a Ti wire is added, then a nitrogen increasing agent is added, chemical components are detected before the steel ladle is taken out of a station, carbon powder and alloy are supplemented according to a detection result, and refining is stopped when the components of the molten steel reach a set target and the temperature of the molten steel reaches 1550-;
s3, continuous casting of small square billets: hoisting the steel ladle to a continuous casting platform, casting the steel ladle into a steel billet, wherein the steel ladle adopts full-process protection casting in the casting process, and the primary cooling water flow is 110-130m 3 H, continuously casting the secondary cooling water with the specific water amount of 0.9-1.3L/kg into qualified billets;
s4, heating by a heating furnace: the cast steel billet enters a heating furnace and is heated to 1120-1220 ℃ in the heating furnace to be rolled into the steel bar with the required specification;
s5, controlled rolling and controlled cooling rolling of the bar: and cooling the rolled steel bar to 1020-.
2. The method for producing a high-strength chloride corrosion-resistant steel reinforcement for a concrete structure according to claim 1, wherein: the chemical components of the steel billet in the step S3 are as follows by weight: c: 0.20-0.30%; si: 0.40-0.60%; mn: 1.20-1.60%; p: less than or equal to 0.030 percent; s: less than or equal to 0.030 percent; ti: 0.010-0.030%; nb: 0.030-0.050%; cr: 1.2-2.0%; n: 0.008% -0.012%; the balance of Fe and inevitable impurity elements.
3. The method for producing a high-strength chloride corrosion-resistant steel reinforcement for a concrete structure according to claim 1, wherein: in the step S2, the content of each component in the molten steel setting component meets the requirements that Ti/C is more than or equal to 0.03, Mn/S is more than or equal to 40 and Cr/N is more than or equal to 100.
4. The method for producing a high-strength chloride corrosion-resistant steel reinforcement for a concrete structure according to claim 1, wherein: in the step S1, the apparatus for smelting the steelmaking raw materials into the molten crude steel is a converter, the steelmaking raw materials are scrap steel and molten iron, and the weight ratio of the scrap steel to the molten iron is 1: 4.
5. The method for producing a high-strength chloride corrosion-resistant steel reinforcement for a concrete structure according to claim 1, wherein: in the step S1, deoxidizer and alloy are added when steel is tapped 1/3, and the sequence is as follows: deoxidizer → FeSi → SiMn → CrFe → NbFe → deoxidizer, and when tapping 3/4, aluminum cake is added for further deoxidation.
6. The method for producing a high-strength chloride corrosion-resistant steel reinforcement for a concrete structure according to claim 1, wherein: and step S2, the refining furnace is an LF furnace, and in the step S2, the ladle is fully bottom-blown with argon to adjust the flow of the argon.
7. The method for producing a high-strength chloride corrosion-resistant steel reinforcement for a concrete structure according to claim 1, wherein: and step S2, the nitrogen content in the nitrogen increasing agent is 28-32%.
8. The method for producing a high-strength chloride corrosion-resistant steel reinforcement for a concrete structure according to claim 1, wherein: the section of the casting blank in the step S3 is 140-170mm 2 。
9. A high-strength chloride corrosion-resistant steel bar for concrete structures produced by the production method according to any one of claims 1 to 8.
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Application publication date: 20220923 |