WO2022151603A1 - 400MPa级耐蚀钢筋及其生产方法 - Google Patents

400MPa级耐蚀钢筋及其生产方法 Download PDF

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WO2022151603A1
WO2022151603A1 PCT/CN2021/086677 CN2021086677W WO2022151603A1 WO 2022151603 A1 WO2022151603 A1 WO 2022151603A1 CN 2021086677 W CN2021086677 W CN 2021086677W WO 2022151603 A1 WO2022151603 A1 WO 2022151603A1
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Prior art keywords
steel bar
furnace
temperature
corrosion
steel
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PCT/CN2021/086677
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English (en)
French (fr)
Inventor
麻晗
周云
赵家七
张宇
陈焕德
Original Assignee
江苏省沙钢钢铁研究院有限公司
江苏沙钢集团有限公司
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Application filed by 江苏省沙钢钢铁研究院有限公司, 江苏沙钢集团有限公司 filed Critical 江苏省沙钢钢铁研究院有限公司
Priority to EP21918802.6A priority Critical patent/EP4279626A1/en
Priority to US18/261,657 priority patent/US20240068064A1/en
Priority to KR1020237023775A priority patent/KR20230118953A/ko
Priority to JP2023543025A priority patent/JP2024504120A/ja
Publication of WO2022151603A1 publication Critical patent/WO2022151603A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • 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
    • B21B1/18—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 in a continuous process
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    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
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    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
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    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/84—Controlled slow cooling
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    • C21D6/00—Heat treatment of ferrous alloys
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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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    • 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
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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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    • C21D8/08—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires for concrete reinforcement
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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
    • C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
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    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • 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
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
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    • C—CHEMISTRY; METALLURGY
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    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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    • C—CHEMISTRY; METALLURGY
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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    • C21D2211/00—Microstructure comprising significant phases
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    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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Definitions

  • the invention belongs to the technical field of metallurgy, and relates to a 400MPa-level corrosion-resistant steel bar and a production method of a 400MPa-level corrosion-resistant steel bar.
  • Reinforced concrete structure is the most widely used structural form in infrastructure construction.
  • the theoretical service life of reinforced concrete structure is long, but there are many cases of premature failure of reinforced concrete in practical projects, which not only increases maintenance costs, but also causes energy and a huge waste of resources.
  • the coastal reinforced concrete structures due to the influence of harsh environments such as high content of chloride ions and sulfates, high temperature and high humidity, have generally suffered severe corrosion damage 10 to 15 years after being put into use, far from reaching The theoretical service life of the design.
  • the concrete in the reinforced concrete structure belongs to a strong alkaline environment.
  • the surface of the steel bar will be passivated to form a stable metal oxide passivation film.
  • the dissolution and repair of the passivation film are theoretically in a state of near equilibrium, so that the potential of each position on the surface of the steel bar is basically the same, so as to ensure that the steel bar is difficult to corrode or the rate of corrosion is very high. Low.
  • stainless steel rebar is a common type of rebar with better corrosion resistance.
  • alloying elements such as Cr, Ni, and Mo
  • the corrosion resistance can be greatly improved compared with ordinary carbon steel rebar, and the corrosion resistance can be greatly improved. It is exceptionally excellent; however, due to the addition of a large number of alloying elements to the stainless steel rebar, its welding performance is very poor, which makes the welding construction cost of the stainless steel rebar very high in actual construction, and there is also a structural instability of the reinforced concrete structure due to poor welding.
  • the purpose of the present invention is to provide a 400MPa grade corrosion-resistant steel bar, which has excellent corrosion resistance, comprehensive mechanical properties and welding properties, and can reduce material cost and The process cost is obtained, and it is suitable for extensive use in marine engineering.
  • an embodiment provides a 400MPa grade corrosion-resistant steel bar, and the chemical composition of the steel bar in mass percentage includes: Cr: 9.5-10.4%, Mo: 1.0-1.2%, Mn: 0.3-0.6 %, Ni: 0.01 ⁇ 1.00%, Cu: 0.01 ⁇ 0.5%, C ⁇ 0.014%, N ⁇ 0.004%, Nb: 0.01 ⁇ 0.05%, Si: 0.2 ⁇ 0.6%, S ⁇ 0.004%, O ⁇ 0.003%, As ⁇ 0.01%, P: 0.01 ⁇ 0.03%, and Cr+Mo+0.5Mn+0.35Ni+0.25Cu is 11.1 ⁇ 12.2%, C+N+0.3Si+Mn+1.8Nb is 0.4 ⁇ 0.8%, the balance For Fe and inevitable impurities.
  • the chemical composition of the steel bar further includes any one or more of: V: 0.1-0.15%, Ti: 0.01-0.05%, Al: 0.01-0.03%, B: 0.0005-0.0020% in mass percentage .
  • microstructure of the steel bar is ferrite and bainite, wherein the proportion of ferrite is 28%-40%.
  • Class A, Class B, Class C and Class D of the steel bar under the GB/T10561 standard are all ⁇ 1.0 grade.
  • the yield strength of the steel bar is ⁇ 420 MPa
  • the tensile strength is ⁇ 540 MPa
  • the elongation after fracture is ⁇ 18%
  • the total elongation at maximum force is ⁇ 7.5%.
  • the nominal diameter of the reinforcing bar is 6-32 mm.
  • the reinforcing bar when the nominal diameter of the reinforcing bar is 6-10 mm, the reinforcing bar is arranged as a coiled bar; when the nominal diameter of the reinforcing bar is 12-32 mm, the reinforcing bar is arranged as a straight bar.
  • the average weight-loss corrosion rate of the steel bar is 0.05-0.1 g/(m 2 ⁇ h); in the salt spray corrosion test, the average weight-loss corrosion rate of the steel bar is 0.01-0.04 g/(m 2 ⁇ h);
  • the self-corrosion potential of the steel bar is -0.1 ⁇ -0.15V
  • the polarization resistance is 2500 ⁇ 3000k ⁇ /cm 2
  • the self-corrosion current density is ⁇ 0.13 ⁇ A/cm 2 .
  • the steel bars can be prepared;
  • the process route 1 includes the molten iron pre-desulfurization process, the converter smelting process, the AOD furnace refining process, the LF furnace refining process, the billet continuous casting process, the hot continuous rolling process and the temperature-controlled cooling process performed in sequence;
  • the second process route includes the molten iron pre-desulfurization process, the converter smelting process, the LF furnace refining process, the RH furnace refining process, the billet continuous casting process, the hot continuous rolling process and the temperature-controlled cooling process.
  • the tapping temperature of the converter smelting process is 1600-1660°C; in the AOD furnace refining process, high-carbon ferrochromium alloy and ferromolybdenum alloy are added to the molten steel to perform preliminary alloying on the molten steel. After reduction, slag removal is carried out, and then manganese alloy is added. Before tapping, the ladle used for tapping is purged with argon gas for more than 5 minutes. During the tapping process, 20 kg of aluminum ingots are added to the molten steel.
  • the tapping temperature is 1630 ⁇ 1670 °C, Tapping C content ⁇ 0.01%; in the refining process of the LF furnace, after the molten steel reaches the ladle of the LF furnace, slag adjustment is carried out according to the scheme of adding 13-15kg lime and 4.0-6.5kg fluorite per ton of molten steel, and the white slag retention time ⁇ 8min, the soft stirring time is 8 ⁇ 15min, the tapping temperature is 1600 ⁇ 1620°C; in the billet continuous casting process, carbon-free mold flux or ultra-low carbon mold flux is used, the continuous casting temperature is 1520 ⁇ 1560°C, and the continuous casting During the process, the pulling speed is 1.2 ⁇ 1.6m/min.
  • micro-carbon ferrochromium alloy is added to the molten steel during the tapping process to perform preliminary alloying of the molten steel, and the tapping temperature is 1700-1750 ° C;
  • the LF furnace During the refining process, the ladle of the LF furnace is bottom-blown with an argon flow rate of 80 to 160 L/min, and the tapping temperature is 1560 to 1600 °C; in the refining process of the RH furnace, after the RH furnace is evacuated for 3 minutes, the Blow oxygen into the RH furnace, the total amount of oxygen blowing is 500-700Nm 3 , and then add micro-carbon ferrochromium alloy to the molten steel to alloy the molten steel.
  • the vacuum degree is less than 2 mbar, carry out net circulation treatment for more than 5 minutes, and the tapping temperature is 1560 ⁇ 1600°C, the C content of the tapping steel is ⁇ 0.015%; in the continuous casting process of the billet, carbon-free mold slag or ultra-low carbon mold slag is used, the continuous casting temperature is 1520 ⁇ 1560°C, and the pulling speed during the continuous casting process is 2.2 ⁇ 2.6m/min.
  • the process route one and the process route two are:
  • the continuous casting slab is heated in a heating furnace, the heating temperature is 1100-1200° C., and the furnace time is 60-120 minutes, and then rolled into straight threaded steel bars with a diameter of 12-32 mm , the rolling temperature is 1000 ⁇ 1100°C, and the finishing rolling temperature is 850 ⁇ 950°C;
  • the rolled straight threaded steel bars are naturally cooled on a cooling bed, and the temperature of the upper cooling bed is 860-920°C.
  • the first process route and the second process route are: in the hot continuous rolling process, the continuous casting slab is heated in a heating furnace, the heating temperature is 1080-1130 ° C, and the furnace time is 60 ⁇ 120min, and then rolled into coiled threaded steel bars with a diameter of 6 ⁇ 10mm.
  • the rolling temperature is 980 ⁇ 1030°C
  • the finishing rolling temperature is 850 ⁇ 950°C
  • the spinning temperature is 830 ⁇ 920°C.
  • both the first process route and the second process route include an online pickling process and a packing process performed in sequence after the temperature control cooling process; in the online pickling process, the steel bars are sequentially subjected to pickling A tank, a passivation tank and a drying device, the air jets of the pickling tank are distributed around the center line of the pickling tank.
  • the fracture point of the obtained welded sample in the tensile test is formed at the base metal of the two steel bars.
  • the beneficial effects of the present invention include:
  • the self-corrosion potential is relatively
  • the positive shift amplitude of ordinary HRB400 exceeds 0.4V, the polarization resistance is much higher than that of ordinary HRB400, and the self-corrosion current density is equivalent to 1/65 of ordinary HRB400 or even lower; welding performance: easy to weld, the structure of the welding point is firm and not easy to break , the fracture point of the welded specimen in the tensile test is formed at the base metal of the steel bar;
  • the purpose of the present invention is to provide a production method of a 400MPa grade corrosion-resistant steel bar, and the obtained steel bar has excellent corrosion resistance, comprehensive mechanical properties and welding performance, and has low The material cost and process cost are suitable for extensive use in marine engineering.
  • an embodiment provides a production method of a 400MPa grade corrosion-resistant steel bar, and the production method comprises the following steps:
  • the molten iron pre-desulfurization process, the converter smelting process, the AOD furnace refining process, and the LF furnace refining process are sequentially used for molten steel smelting, or the molten iron pre-desulfurization process, the converter smelting process, the LF furnace refining process, and the RH furnace refining process are sequentially used for molten steel smelting.
  • the molten steel is continuously cast into a billet, and the chemical composition of the billet in terms of mass percentage includes: Cr: 9.5-10.4%, Mo: 1.0-1.2%, Mn: 0.3-0.6%, Ni: 0.01-1.00%, Cu: 0.01- 0.5%, C ⁇ 0.014%, N ⁇ 0.004%, Nb: 0.01 ⁇ 0.05%, Si: 0.2 ⁇ 0.6%, S ⁇ 0.004%, O ⁇ 0.003%, As ⁇ 0.01%, P: 0.01 ⁇ 0.03%, and Cr+Mo+0.5Mn+0.35Ni+0.25Cu is 11.1-12.2%, C+N+0.3Si+Mn+1.8Nb is 0.4-0.8%, and the balance is Fe and inevitable impurities.
  • the billet obtained in step 1 is heated in a heating furnace, the heating temperature is 1100-1200 ° C, and the furnace time is 60-120 min, and then rolled into straight threaded steel bars with a diameter of 12-32 mm, and the rolling temperature is 1000 ⁇ 1100°C, the finishing rolling temperature is 850 ⁇ 950°C; then the rolled straight threaded steel bars are naturally cooled on the cooling bed, and the temperature of the upper cooling bed is 860 ⁇ 920°C;
  • the billet obtained in step 1 is heated in a heating furnace, the heating temperature is 1080-1130 ° C, and the furnace time is 60-120 min, and then rolled into a coiled threaded steel bar with a diameter of 6-10 mm, and the rolling temperature is The temperature is 980-1030°C, the finishing temperature is 850-950°C, and the spinning temperature is 830-920°C; then the rolled coiled threaded steel bar is cooled by delayed Stellmor, and the fans below the roller table are all turned off.
  • the chemical composition of the steel billet in terms of mass percentage, further comprises: V: 0.1-0.15%, Ti: 0.01-0.05%, Al: 0.01-0.03%, B: 0.0005-0.0020% Any one or more.
  • step 1 if the molten iron pre-desulfurization process, the converter smelting process, the AOD furnace refining process, and the LF furnace refining process are successively used for molten steel smelting, then: the tapping temperature of the converter smelting process is 1600-1660 ° C; During the refining process of the AOD furnace, high-carbon ferrochromium alloy and ferromolybdenum alloy are added to molten steel to carry out preliminary alloying of molten steel, slag removal is carried out after reduction, and manganese alloy is then added, and the ladle used for tapping is blown with argon before tapping.
  • the tapping temperature is 1630-1670 ° C, and the tapping C content is ⁇ 0.01%; during the refining process of the LF furnace, after the molten steel reaches the ladle of the LF furnace, according to The scheme of adding 13-15kg lime and 4.0-6.5kg fluorite per ton of molten steel is used for slag adjustment, the retention time of white slag is ⁇ 8min, the soft stirring time is 8-15min, and the tapping temperature is 1600-1620°C; , using carbon-free mold slag or ultra-low carbon mold slag, the continuous casting temperature is 1520 ⁇ 1560 °C, and the pulling speed during the continuous casting process is 1.2 ⁇ 1.6m/min;
  • the molten iron pre-desulfurization process, the converter smelting process, the LF furnace refining process, and the RH furnace refining process are sequentially used for molten steel smelting, then: during the converter smelting process, micro-carbon ferrochrome is added to the molten steel during the tapping process to reduce the molten steel.
  • Preliminary alloying is carried out, and the tapping temperature is 1700-1750 °C; during the refining process of the LF furnace, the ladle of the LF furnace is bottom-blown with an argon flow rate of 80-160 L/min, and the tapping temperature is 1560-1600 °C; In the refining process of the RH furnace, after the RH furnace is evacuated for 3 minutes, oxygen is blown into the RH furnace, and the total amount of oxygen blown is 500-700 Nm 3 , and then micro-carbon ferrochrome is added to the molten steel to alloy the molten steel.
  • the tapping temperature is 1560-1600 ° C, and the C content in tapping is ⁇ 0.015%; in the billet continuous casting process, carbon-free mold slag or ultra-low carbon mold slag is used to continuously
  • the casting temperature is 1520 ⁇ 1560°C, and the pulling speed is 2.2 ⁇ 2.6m/min during the continuous casting.
  • the production method also comprises step (3) online pickling:
  • the steel bars obtained in step 2 are sequentially passed through a pickling tank, a passivation tank and a drying equipment for online pickling, and the air jets of the pickling tank are distributed around the center line of the pickling tank; Pack after drying.
  • the fracture point of the obtained welded sample in the tensile test is formed on the base metal of the two steel bars. place.
  • microstructure of the steel bar prepared by the production method is ferrite and bainite, wherein the proportion of ferrite is 28%-40%.
  • Class A, Class B, Class C and Class D of the steel bars prepared by the production method under the GB/T10561 standard are all less than or equal to grade 1.0.
  • the yield strength of the steel bar prepared by the production method is ⁇ 420 MPa
  • the tensile strength is ⁇ 540 MPa
  • the elongation after fracture is ⁇ 18%
  • the total elongation at maximum force is ⁇ 7.5%.
  • the average weight loss corrosion rate of the steel bars is 0.05-0.1 g/(m 2 ⁇ h); in the salt spray corrosion test, all The average weight loss corrosion rate of the steel bars is 0.01 ⁇ 0.04g/(m 2 ⁇ h);
  • the self-corrosion potential of the steel bar is -0.1 ⁇ -0.15V
  • the polarization resistance is 2500 ⁇ 3000k ⁇ /cm 2
  • the self-corrosion current density is ⁇ 0.13 ⁇ A/cm 2 .
  • the beneficial effects of the present invention include:
  • the self-corrosion potential is relatively
  • the positive shift amplitude of ordinary HRB400 exceeds 0.4V, the polarization resistance is much higher than that of ordinary HRB400, and the self-corrosion current density is equivalent to 1/65 of ordinary HRB400 or even lower; welding performance: easy to weld, the structure of the welding point is firm and not easy to break , the fracture point of the welded specimen in the tensile test is formed at the base metal of the steel bar;
  • This embodiment provides a corrosion-resistant steel bar, especially a hot-rolled ribbed steel bar, the chemical composition of which, in terms of mass percentage, includes: Cr: 9.5-10.4%, Mo: 1.0-1.2%, Mn: 0.3-0.6% , Ni: 0.01 ⁇ 1.00%, Cu: 0.01 ⁇ 0.50%, C ⁇ 0.014%, N ⁇ 0.004%, Nb: 0.01 ⁇ 0.05%, Si: 0.2 ⁇ 0.6%, S ⁇ 0.004%, O ⁇ 0.003%, As ⁇ 0.01%, P: 0.01-0.03%, the balance is Fe and inevitable impurities.
  • the mass percentages of Cr, Mo, Mn, Ni and Cu in the chemical composition of the steel bar also satisfy: 11.1% ⁇ Cr+Mo+0.5Mn+0.35Ni+0.25Cu ⁇ 12.2%; while C, N, Si, The mass percentages of Mn and Nb also satisfy 0.4% ⁇ C+N+0.3Si+Mn+1.8Nb ⁇ 0.8%.
  • Cr an important corrosion-resistant element, which can form an oxide passivation film on the surface of the steel bar, thereby effectively preventing the oxidation of the steel bar and improving the corrosion resistance of the steel bar matrix; especially when it coexists with Mo, Ni and other elements, the steel bar can be obtained. Better corrosion resistance and avoid pitting corrosion; in addition, Cr element can also improve the hardenability of steel bars; in the chemical composition design of the present invention, the Cr content is controlled at 9.5-10.4%.
  • Mo An important corrosion-resistant element, whether in the environment of reducing acid or in the environment of strong oxidizing salt solution, the addition of Mo element can passivate the surface of the steel bar, and can also prevent the steel bar from being exposed to chlorides. Pitting corrosion occurs in the solution, thereby improving the corrosion resistance of steel bars in various environments as a whole; in addition, Mo element has a very obvious inhibitory effect on pearlite transformation, and at the same time, combined with carbide forming element Cr, it can promote the bainite transformation.
  • Mo element can promote grain refinement and improve the hardenability and thermal strength of steel bars; however, when the Mo content is too high, the oxidation resistance of steel bars will deteriorate; in the chemical composition design of the present invention, Mo content is controlled at 1.0-1.2%.
  • Mn a solid solution strengthening element, which can improve the strength of the wire rod, and can also be combined with the harmful element S to reduce the hot brittleness of the steel bar; it is also an important deoxidizer, desulfurizer, and austenite forming element; however, the content of Mn is too high , the plasticity, impact toughness, welding performance, etc. of the steel bar will decrease; in the chemical composition design of the present invention, the Mn content is controlled at 0.3-0.6%.
  • Ni An important corrosion-resistant element, which makes the steel bar have high corrosion resistance to acid and alkali environments, and makes the steel bar have high rust resistance and heat resistance at high temperatures; at the same time, Ni element is an austenite forming element , which can make the steel have a uniform austenite structure to improve the corrosion resistance; in the chemical composition design of the present invention, the Ni content is controlled at 0.01-1.00%.
  • Cu an important corrosion-resistant element, which helps to improve the corrosion resistance of steel bars. However, when the Cu content is too high, the plasticity of the steel will be reduced, resulting in hot rolling cracking; in the chemical composition design of the present invention, the Cu content is controlled at 0.01 ⁇ 0.50%.
  • C Austenite forming element, controlling the carbon content to keep below the dissolution limit of ferrite can improve the uniformity of the steel structure and composition distribution, reduce the potential difference between the various regions inside the steel bar, thereby reducing the corrosion rate.
  • the C content is controlled below 0.014%.
  • N Austenite forming element, if the N content is too high, it will reduce the plasticity of the steel bar, and it will also be unfavorable for the control of the ratio of ferrite and bainite in the steel bar structure.
  • the N content is controlled at 0.004 %the following.
  • Nb Microalloy strengthening element, which can play the role of precipitation strengthening and grain refinement strengthening in the rolling process (such as the hot continuous rolling process described later); however, excessive Nb content will reduce the plasticity of steel bars, The cost increases; in the chemical composition design of the present invention, the Nb content is controlled at 0.01-0.05%.
  • Si a solid solution strengthening element, which is dissolved in ferrite and can inhibit the diffusion of C element in austenite, delay the transformation of ferrite and pearlite, and improve the yield strength and tensile strength of steel bars; however, the Si content Too high will reduce the plasticity of the steel and deteriorate the welding performance of the steel bar; in the chemical composition design of the present invention, the Si content is controlled at 0.2-0.6%.
  • P It can improve the strength and corrosion resistance of steel bars, but segregation is easy to occur in steel, and excessive P content will lead to poor mechanical properties at low temperature.
  • the P content is controlled at 0.01-0.03% .
  • Cr+Mo+0.5Mn+0.35Ni+0.25Cu It is very important for the comprehensive control of the corrosion resistance, plasticity and cost of the steel bar.
  • the oxide film on the surface of the steel bar has sufficient density to improve the corrosion resistance and repair of the steel bar matrix.
  • it is beneficial to control the microstructure and proportion of the steel bar to improve the plasticity of the steel bar increase the elongation after fracture and The maximum force total elongation, on the other hand, also reduces the addition of precious alloying elements, reduces costs, and promotes engineering promotion, design and use.
  • Cr+Mo+0.5Mn+0.35Ni+0.25 Cu satisfies 11.1 to 12.2%.
  • C+N+0.3Si+Mn+1.8Nb It is very important to comprehensively control the strength, plasticity and other mechanical properties of steel bars. On the one hand, to ensure that the alloy elements can give full play to their respective solid solution strengthening, precipitation strengthening and microstructure strengthening. On the other hand, avoid the low proportion of ferrite in the steel structure and avoid the high proportion of bainite in the steel structure, that is, optimize the respective proportions of ferrite and bainite in the steel structure, To improve the plasticity of the steel bar, increase the elongation after fracture and the total elongation at maximum force, in the chemical composition design of the present invention, C+N+0.3Si+Mn+1.8Nb satisfies 0.4-0.8%.
  • the proportion is 60% to 72%, and the steel bar has excellent corrosion resistance, comprehensive mechanical properties and welding performance, and the overall comprehensive performance is excellent, which is suitable for the use requirements of marine engineering;
  • (2) In the above chemical composition design scheme Under the circumstance, not only can it achieve excellent corrosion resistance, comprehensive mechanical properties and welding performance, but also the cost of alloying elements is low, energy saving and consumption reduction, and can be prepared through multiple process routes, reducing the cost of the production process, suitable for In actual production and processing, it has higher social significance and economic effect.
  • the microstructure of the steel bar is ferrite and bainite, wherein the proportion of ferrite is 28%-40%, and the proportion of bainite is 60%-72%.
  • one is the mechanical properties.
  • the ratio of ferrite to bainite in this embodiment is controlled to ensure that High yield strength and good elongation, including elongation after fracture and total elongation at maximum force, ensure good comprehensive mechanical properties; on the other hand, corrosion resistance, ensuring a certain proportion of bainite structure, can improve the strength of steel bars. Corrosion resistance.
  • the steel bar is a steel bar above 400MPa, and its yield strength is ⁇ 420MPa, tensile strength is greater than or equal to 540MPa, elongation after fracture is greater than or equal to 18%, and total elongation at maximum force is greater than or equal to 7.5%.
  • the steel bars are also well controlled in terms of inclusions. Specifically, the inclusions of Class A, Class B, Class C, and Class D of the reinforcing bars under the GB/T10561 standard are all less than or equal to 1.0. The toughness of the steel bar under low temperature conditions can be improved, which is beneficial to ensure the mechanical properties of the steel bar.
  • the corrosion resistance of the steel bar is more than 45 times higher than that of ordinary HRB400 in the weekly immersion corrosion test and the salt spray corrosion test.
  • the average weight-loss corrosion rate of the steel bar was 0.05-0.1 g/(m 2 ⁇ h); in the salt spray corrosion test, the average weight-loss corrosion rate of the steel bar was 0.01-0.04 g/(m 2 ⁇ h);
  • the self-corrosion potential of the steel bar is -0.1 ⁇ -0.15V
  • the polarization resistance is 2500 ⁇ 3000k ⁇ /cm 2
  • the self-corrosion current density is ⁇ 0.13 ⁇ A/cm 2 .
  • the concrete method of the weekly immersion corrosion test adopted is: place the treated sample in the weekly immersion test box, and the test is carried out according to the corrosion test method of YB/T4367 steel bar in chloride ion environment, and the solution is 2.0 ⁇ 0.05 (wt %) NaCl, the pH is 6.5 ⁇ 7.2, the solution temperature is 45°C ⁇ 2°C, the drying temperature is 70°C ⁇ 10°C, and the average weight loss corrosion rate at 168h is obtained by continuous test.
  • the specific method of the salt spray corrosion test used is: place the treated sample in the salt spray test box, and the test is carried out according to GB/T10125 artificial atmosphere corrosion test-salt spray corrosion test, and the solution is 2.0 ⁇ 0.05 (wt%).
  • NaCl, pH is 6.5 ⁇ 7.2
  • solution temperature is 35°C ⁇ 2°C
  • the average weight loss corrosion rate at 168h is obtained by continuous test.
  • the self-corrosion potential of the steel bar is -0.1 ⁇ -0.15V, which is more than 0.4 V compared to the normal HRB400.
  • the polarization resistance of the steel bar is 2500-3000k ⁇ /cm 2 , which is much higher than that of ordinary HRB400
  • the self-corrosion current density of the steel bar is ⁇ 0.13 ⁇ A/cm 2 , which is equivalent to 1/65 of the ordinary HRB400 or even lower .
  • the specific method of the electrochemical corrosion test adopted is: the electrochemical test is carried out in accordance with GB/T24196-2009 "Guidelines for Potentiostatic and Potentiodynamic Polarization Measurement of Electrochemical Test Methods for Corrosion of Metals and Alloys", using a three-electrode system , the reference electrode is a saturated calomel electrode, the auxiliary electrode is a Pt sheet, and the test solution is a simulated concrete pore liquid with a chloride ion concentration of ⁇ 3 mol/L; the test scanning range of the polarization curve is -300 ⁇ 600mV relative to the self-corrosion potential of the sample , the scanning frequency is 1mV/s; the scanning frequency range of electrochemical impedance test is 10 -2 ⁇ 10 5 Hz, and the amplitude of AC excitation signal is ⁇ 5mV.
  • the steel bar has excellent corrosion resistance, and in the case of simulating the corrosion performance test in seawater solution, all indicators are far better than ordinary rebars of the same level.
  • the steel bars are easy to weld.
  • the structure of the welding point is firm and not easy to break.
  • the breaking point of the welding sample in the tensile test is formed at At the base metal of the reinforcement, not at the location of the welding point.
  • the nominal diameter of the reinforcing bar is 6-32 mm.
  • the reinforcing bar when the nominal diameter of the reinforcing bar is 6-10 mm, the reinforcing bar is arranged as a coiled bar; when the nominal diameter of the reinforcing bar is 12-32 mm, the reinforcing bar is arranged as a straight bar. In this way, the requirements for steel bars in marine engineering can be met, and through the design of the diameter, the comprehensive mechanical properties and corrosion resistance of the steel structure can also be improved.
  • This embodiment provides a corrosion-resistant steel bar, specifically a hot-rolled ribbed steel bar suitable for marine engineering.
  • the main difference from the aforementioned first embodiment is that the chemical composition is further increased by V: 0.1-0.15% , Ti: 0.01-0.05%, Al: 0.01-0.03%, B: 0.0005-0.0020% any one or more, so as to further improve the performance of the steel bar.
  • the chemical composition of the steel bar includes in mass percentage: Cr: 9.5-10.4%, Mo: 1.0-1.2%, Mn: 0.3-0.6%, Ni: 0.01-1.00%, Cu : 0.01 ⁇ 0.50%, C ⁇ 0.014%, N ⁇ 0.004%, Nb: 0.01 ⁇ 0.05%, Si: 0.2 ⁇ 0.6%, S ⁇ 0.004%, O ⁇ 0.003%, As ⁇ 0.01%, P: 0.01 ⁇ 0.03 %, and any one or more of V: 0.1-0.15%, Ti: 0.01-0.05%, Al: 0.01-0.03%, B: 0.0005-0.0020%, and the balance is Fe and inevitable impurities.
  • the mass percentages of Cr, Mo, Mn, Ni and Cu in the chemical composition of the steel bar also satisfy: 11.1% ⁇ Cr+Mo+0.5Mn+0.35Ni+0.25Cu ⁇ 12.2%; And the mass percentages of C, N, Si, Mn and Nb also satisfy 0.4% ⁇ C+N+0.3Si+Mn+1.8Nb ⁇ 0.8%.
  • V A microalloy strengthening element, which can precipitate V(C,N) compounds during the rolling process (such as the hot continuous rolling process below), which has a certain precipitation strengthening effect and prevents austenite and ferrite grains at the same time. It grows up and has the effect of fine-grain strengthening; however, if the V content is too high, it will reduce the plasticity of the steel bar and increase the cost. In the chemical composition design of the present invention, the V content is controlled at 0.1-0.15%.
  • Ti The affinity with the element C is larger than that of Cr, which can avoid the precipitation of chromium carbide and the occurrence of poor chromium at the grain boundary, thereby effectively preventing intergranular corrosion; and adding an appropriate amount of Ti can form finely dispersed TiOx and TiN in the steel plate; However, if the Ti content is too high, the viscosity of molten steel will increase, which is not conducive to the smelting of molten steel, and at the same time, the size of the formed TiOx will be large, which will deteriorate the toughness of the steel plate. In the chemical composition design of the present invention, the Ti content is controlled at 0.01 ⁇ 0.05%.
  • Al A commonly used deoxidizer, which can increase the electrode potential of the steel bar matrix and improve the corrosion resistance; and can prevent the growth of austenite grains and improve the strength of the steel bar; however, excessive Al content may lead to an increase in oxides in the steel. , will be detrimental to the weldability of the steel bar; in the chemical composition design of the present invention, the Al content is controlled at 0.01-0.03%.
  • B strengthening element, which has a significant effect on improving the strength of steel bars, but too high content of B is unfavorable for the improvement of intergranular corrosion resistance; in the chemical composition design of the present invention, the content of B is controlled at 0.0005-0.0020%.
  • the performance of the steel bar can be further improved on the basis of the first embodiment, and the steel bar has more excellent performance.
  • Corrosion resistance, mechanical strength, plasticity and welding performance are not only convenient for engineering construction, but also have a longer theoretical service life when used in marine engineering.
  • This embodiment provides a method for producing a corrosion-resistant steel bar, which can be used not only for the production and preparation of the corrosion-resistant steel bar of the foregoing first embodiment, but also for the production and preparation of the foregoing second embodiment of the corrosion-resistant steel bar.
  • the process route of the production method includes the molten iron pre-desulfurization process, the converter smelting process, the AOD furnace refining process, the LF furnace refining process, the billet continuous casting process, the hot continuous rolling process, and the temperature control process. Cooling process and packing process.
  • the production method will be described in detail below according to the sequence of steps.
  • the molten iron pre-desulfurization process, the converter smelting process, the AOD furnace refining process, and the LF furnace refining process are successively used for molten steel smelting, and the obtained molten steel is continuously cast into a billet using the billet continuous casting process.
  • the chemical composition of the steel billet obtained in this step is consistent with the chemical composition of the steel bar of the first embodiment, that is, the obtained steel billet.
  • the chemical composition in mass percentage includes: Cr: 9.5 ⁇ 10.4%, Mo: 1.0 ⁇ 1.2%, Mn: 0.3 ⁇ 0.6%, Ni: 0.01 ⁇ 1.00%, Cu: 0.01 ⁇ 0.50%, C ⁇ 0.014%, N ⁇ 0.004%, Nb: 0.01 ⁇ 0.05%, Si: 0.2 ⁇ 0.6%, S ⁇ 0.004%, O ⁇ 0.003%, As ⁇ 0.01%, P: 0.01 ⁇ 0.03%, and Cr+Mo+0.5Mn+0.35Ni +0.25Cu is 11.1-12.2%, C+N+0.3Si+Mn+1.8Nb is 0.4-0.8%, and the balance is Fe and inevitable impurities;
  • the chemical composition of the steel billet obtained in this step is consistent with the chemical composition of the steel bar of the
  • tapping temperature of the converter smelting process is 1600-1660° C., which ensures the effect of removing C and P, and is beneficial to subsequent alloying.
  • the tapping temperature is 1630 ⁇
  • the C content of tapping is ⁇ 0.01%, which ensures the decarburization effect of molten steel and the production rhythm.
  • the slag is adjusted according to the scheme of adding 13-15kg lime and 4.0-6.5kg fluorite per ton of molten steel, the white slag retention time is ⁇ 8min, and the soft stirring time is 8 ⁇ 15min, the tapping temperature is 1600 ⁇ 1620°C, and the deoxidation and desulfurization of molten steel is gradually completed.
  • the tapping molten steel in the LF furnace refining process is continuously cast into billets, wherein carbon-free mold slag or ultra-low carbon mold slag is used to prevent the carbonization of molten steel, and the continuous casting temperature is 1520-1560 °C. °C, the pulling speed in the continuous casting process is 1.2 ⁇ 1.6m/min to ensure continuous casting.
  • the steel billet obtained in step 1 is rolled into a steel bar with a nominal diameter of 6-32 mm through a hot continuous rolling process, and then a temperature-controlled cooling process is performed. According to the difference of the nominal diameter of the steel bar, the specific process plan of this step is different.
  • step 1 during the hot continuous rolling process, the steel billet obtained in step 1 is heated in a heating furnace, and the heating temperature is 1100-1200 ° C, and The time in the furnace is 60-120min, the alloying elements are fully redissolved, which is beneficial to the strengthening effect of the alloying elements, and then rolled into straight threaded steel bars with a diameter of 12-32mm.
  • the rolling temperature is 1000-1100 °C, and the finishing temperature is 850 ⁇ 950°C to keep the austenite grains at a certain size; then in the temperature-controlled cooling process, the rolled straight threaded steel bars are naturally cooled on a cooling bed, and the temperature of the upper cooling bed is 860-920°C , to ensure the subsequent ferrite and pearlite size and proportion control.
  • the billet obtained in step 1 is heated in a heating furnace, and the heating temperature is 1080-1130 ° C, which is conducive to sufficient alloying elements Re-melting, and the furnace time is 60-120min, and then rolled into coiled threaded steel bars with a diameter of 6-10mm.
  • the rolling temperature is 980-1030°C
  • the finishing temperature is 850-950°C
  • the spinning temperature is 830-920°C.
  • the steel bars cooled in step 2 are packaged for transportation and engineering application.
  • This embodiment provides a method for producing a corrosion-resistant steel bar, which can be used for both the production and preparation of the corrosion-resistant steel bar of the foregoing first embodiment and the production and preparation of the corrosion-resistant steel bar of the foregoing second embodiment.
  • the process route of the production method includes the molten iron pre-desulfurization process, the converter smelting process, the LF furnace refining process, the RH furnace refining process, the billet continuous casting process, the hot continuous rolling process, and the temperature control process. Cooling process and packing process. That is, the present embodiment differs from the aforementioned third embodiment only in the molten iron pre-desulfurization process, the converter smelting process, the LF furnace refining process, the RH furnace refining process, and the billet continuous casting process, that is, the steelmaking process.
  • the production method of this embodiment will only be described in detail below with regard to the steelmaking step.
  • the molten iron pre-desulfurization process, the converter smelting process, the LF furnace refining process, and the RH furnace refining process are successively used for molten steel smelting, and the obtained molten steel is continuously cast into a billet using the billet continuous casting process.
  • the chemical composition of the steel billet obtained in this step is consistent with the chemical composition of the steel bar of the first embodiment, that is, the obtained steel billet.
  • the chemical composition in mass percentage includes: Cr: 9.5 ⁇ 10.4%, Mo: 1.0 ⁇ 1.2%, Mn: 0.3 ⁇ 0.6%, Ni: 0.01 ⁇ 1.00%, Cu: 0.01 ⁇ 0.50%, C ⁇ 0.014%, N ⁇ 0.004%, Nb: 0.01 ⁇ 0.05%, Si: 0.2 ⁇ 0.6%, S ⁇ 0.004%, O ⁇ 0.003%, As ⁇ 0.01%, P: 0.01 ⁇ 0.03%, and Cr+Mo+0.5Mn+0.35Ni +0.25Cu is 11.1-12.2%, C+N+0.3Si+Mn+1.8Nb is 0.4-0.8%, and the balance is Fe and inevitable impurities;
  • the chemical composition of the steel billet obtained in this step is consistent with the chemical composition of the steel bar of the second
  • micro-carbon ferrochromium alloy is added to molten steel in the tapping process to carry out preliminary alloying of molten steel, and the C content in molten steel is controlled from the angle of alloy addition as much as possible to improve efficiency, and the tapping temperature is 1700 °C. ⁇ 1750°C to ensure the dephosphorization effect and prepare for the subsequent smelting.
  • the ladle of the LF furnace is bottom-blown with an argon flow rate of 80-160 L/min throughout the whole process, and the tapping temperature is 1560-1600 °C to ensure the dissolution and homogenization of the alloy in the ladle, which is conducive to the control of production rhythm.
  • the tapping molten steel in the LF furnace refining process is continuously cast into billets, wherein carbon-free mold slag or ultra-low carbon mold slag is used to prevent the carbonization of molten steel, and the continuous casting temperature is 1520-1560 °C. °C, the pulling speed in the continuous casting process is 2.2 ⁇ 2.6m/min, which is conducive to continuous casting.
  • controlled rolling and controlled cooling step in step 2 and the packaging process in step 3 are the same as those in the third embodiment, and will not be repeated here.
  • This embodiment provides a method for producing a corrosion-resistant steel bar, the process route of which includes a molten iron pre-desulfurization process, a converter smelting process, a LF furnace refining process, a RH furnace refining process, a billet continuous casting process, and a hot continuous rolling process. process, temperature-controlled cooling process, online pickling process and packaging process.
  • the process from the molten iron pre-desulfurization process to the temperature-controlled cooling process can be specifically implemented by the aforementioned third embodiment or the aforementioned fourth embodiment, that is, this embodiment is implemented in the aforementioned
  • an on-line pickling process is added before the packaging process. The following only introduces the on-line pickling process, and the rest will not be repeated.
  • the steel bars are sequentially passed through the pickling tank, the passivation tank and the drying equipment to realize the online pickling of the steel bars.
  • the air jets of the pickling tank are distributed around the center line of the pickling tank to enhance the effect of pickling.
  • Embodiments 1 to 16 of the present invention are provided below to further illustrate the present invention. It can be understood that the following are only some preferred embodiments of the present invention, rather than all implementations of the present invention, and other embodiments based on the foregoing embodiments do not depart from the technical spirit of the present invention.
  • Examples 1 to 16 and Comparative Examples 1 to 4 all provide a steel bar, and the chemical composition of the steel bar is shown in Table 1. Among them, Example 12 was implemented according to the aforementioned first embodiment of the present invention, and the remaining examples were implemented according to the aforementioned second embodiment of the present invention, and Comparative Examples 1 to 4 did not satisfy any of the embodiments of the present invention.
  • Embodiments 1 to 8 adopt and include the molten iron pre-desulfurization process, the converter smelting process, the AOD furnace refining process, the LF furnace refining process, the billet continuous casting process, the hot continuous rolling process, the temperature-controlled cooling process and The process route of the online pickling process is described below.
  • molten iron pre-desulfurization process carry out pre-desulfurization to molten iron
  • AOD furnace refining process adding high carbon ferrochromium alloy and ferromolybdenum alloy to molten steel to perform preliminary alloying of molten steel, slag removal after reduction, then adding manganese alloy, and blowing the ladle used for tapping with argon before tapping Sweep for more than 5 minutes, add 20kg of aluminum ingots to the molten steel during the tapping process, the tapping temperature is 1630-1670 °C, and the tapping C content is less than or equal to 0.010%;
  • Billet continuous casting process the tapping molten steel in the LF furnace refining process is continuously cast into a billet, wherein carbon-free mold slag or ultra-low carbon mold slag is used, and the continuous casting temperature is 1520-1560 ° C.
  • the continuous casting process The middle pulling speed is 1.2 ⁇ 1.6m/min;
  • Hot continuous rolling process In Examples 1 to 4, the billet was heated in a heating furnace at a heating temperature of 1100 to 1200° C., and the furnace time was 60 to 120 minutes, and then rolled to a diameter of 12 to 120 minutes. 32mm straight threaded steel bar, the rolling temperature is 1000-1100 °C, and the finishing rolling temperature is 850-950 °C; in Examples 5-8, the billet is heated in a heating furnace, and the heating temperature is 1080-1130 °C, and The time in the furnace is 60 to 120 minutes, and then rolled into coiled threaded steel bars with a diameter of 6 to 10 mm. The rolling temperature is 980 to 1030 °C, the finishing temperature is 850 to 950 °C, and the spinning temperature is 830 to 920 °C;
  • On-line pickling process the steel bars are sequentially passed through the pickling tank, the passivation tank and the drying equipment to realize the on-line pickling of the steel bars, wherein the air jet of the pickling tank surrounds the center of the pickling tank Line distribution, and then packing.
  • Examples 9 to 16 adopt the following steps: the molten iron pre-desulfurization process, the converter smelting process, the LF furnace refining process, the RH furnace refining process, the billet continuous casting process, the hot continuous rolling process, the temperature-controlled cooling process and The process route of the online pickling process is described below.
  • Hot metal pre-desulfurization process pre-desulfurize molten iron, after desulfurization, S ⁇ 0.001%, and slag removal rate ⁇ 95%;
  • Converter smelting process adding micro-carbon ferrochromium alloy to molten steel during the tapping process to perform preliminary alloying of molten steel, and the tapping temperature is 1700-1750 °C;
  • Billet continuous casting process the tapping molten steel in the LF furnace refining process is continuously cast into a billet, wherein carbon-free mold slag or ultra-low carbon mold slag is used, and the continuous casting temperature is 1520-1560 ° C.
  • the continuous casting process The middle pulling speed is 2.2 ⁇ 2.6m/min;
  • Hot continuous rolling process In Examples 9 to 12, the billet was heated in a heating furnace at a heating temperature of 1100 to 1200° C., and the furnace time was 60 to 120 minutes, and then rolled to a diameter of 12 to 120 minutes. 32mm straight threaded steel bar, the rolling temperature is 1000-1100 °C, and the finishing rolling temperature is 850-950 °C; in Examples 13-16, the billet is heated in a heating furnace, and the heating temperature is 1080-1130 °C, and The time in the furnace is 60 to 120 minutes, and then rolled into coiled threaded steel bars with a diameter of 6 to 10 mm. The rolling temperature is 980 to 1030 °C, the finishing temperature is 850 to 950 °C, and the spinning temperature is 830 to 920 °C;
  • the production methods used in Comparative Examples 1 to 4 are the traditional process routes of converter smelting, billet continuous casting, hot continuous rolling, and cooling bed cooling.
  • the heating temperature in the heating furnace is 1210-1290 °C. °C
  • the rolling temperature is 1090 ⁇ 1170°C
  • the temperature of the upper cooling bed is ⁇ 1100°C
  • the cooling bed is naturally cooled.
  • Examples 1 to 16 are significantly better than Comparative Examples 1 to 4 in terms of mechanical properties, which meet the requirements of 400MPa seismic steel bars, and have yield strength ⁇ 420 MPa, tensile strength ⁇ 540 MPa, and elongation after fracture. Elongation ⁇ 18%, total elongation at maximum force ⁇ 7.5%.
  • Example 10 492 627 twenty four 15.9
  • Example 11 480 626 twenty four 14.8
  • the concrete method of the weekly immersion corrosion test adopted is: place the treated sample in the weekly immersion test box, and the test is carried out according to the corrosion test method of YB/T4367 steel bar in chloride ion environment, and the solution is 2.0 ⁇ 0.05 (wt %) NaCl, the pH is 6.5 ⁇ 7.2, the solution temperature is 45°C ⁇ 2°C, the drying temperature is 70°C ⁇ 10°C, and the average weight loss corrosion rate at 168h is obtained by continuous test.
  • the specific method of the salt spray corrosion test used is: place the treated sample in the salt spray test box, and the test is carried out according to GB/T10125 artificial atmosphere corrosion test-salt spray corrosion test, and the solution is 2.0 ⁇ 0.05 (wt%).
  • NaCl, pH is 6.5 ⁇ 7.2
  • solution temperature is 35°C ⁇ 2°C
  • the average weight loss corrosion rate at 168h is obtained by continuous test.
  • the specific method of the electrochemical corrosion test used is: the electrochemical test is carried out in accordance with GB/T24196-2009 "Guidelines for Potentiostatic and Potentiodynamic Polarization Measurements of Electrochemical Test Methods for Corrosion of Metals and Alloys", using a three-electrode system, reference
  • the specific electrode is a saturated calomel electrode
  • the auxiliary electrode is a Pt sheet
  • the test solution is a simulated concrete pore liquid with a chloride ion concentration ⁇ 3mol/L
  • the polarization curve test scan range is -300-600mV relative to the self-corrosion potential of the sample
  • the frequency is 1mV/s
  • the scanning frequency range of electrochemical impedance test is 10 -2 ⁇ 10 5 Hz
  • the amplitude of AC excitation signal is ⁇ 5mV.
  • Examples 1 to 16 are significantly better than Comparative Examples 1 to 4 in terms of corrosion resistance, and in the weekly immersion corrosion test, the average weight loss corrosion rate of the steel bars is 0.05 to 0.1 g/g/ (m 2 ⁇ h); in the salt spray corrosion test, the average weight loss corrosion rate of the steel bar is 0.01-0.04g/(m 2 ⁇ h), and the corrosion resistance is more than 45 times higher than that of ordinary HRB400; in electrochemical In the corrosion test, in the simulated concrete pore liquid with chloride ion concentration ⁇ 3mol/L: the self-corrosion potential of the steel bar is -0.1 ⁇ -0.15V, which is more than 0.4V relative to the normal HRB400; The chemical resistance is 2500-3000k ⁇ /cm 2 , which is much higher than that of ordinary HRB400; the self-corrosion current density of the steel bar is ⁇ 0.13 ⁇ A/cm 2 , which is equivalent to 1/65 or even lower than that of ordinary HRB400.
  • Examples 1 to 16 were sampled for inclusion detection and microstructure detection.
  • the inclusions of Type A, Type B, Type C, and Type D under the GB/T10561 standard were all ⁇ 1.0 grade, while the microstructure was less than or equal to 1.0.
  • the proportion of ferrite is 28% to 40%, and the proportion of bainite is 60% to 72%.
  • the steel bars of Examples 1 to 16 were sampled and tested by electroslag pressure welding respectively, and the welded samples were stretched according to the standard room temperature test method of GBT228.1-2010 Tensile Test for Metal Materials Part 1 In the test, the fracture point of the welded sample in the tensile test is formed at the base metal of the steel bar, not at the position of the welding point, which shows that the welding performance of the obtained steel bar is excellent.

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Abstract

本发明揭示了一种400MPa级耐蚀钢筋及其生产方法。钢筋化学成分包括：铬:9.5～10.4％，钼:1.0～1.2％，锰:0.3～0.6％，镍:0.01～1％，铜:0.01～0.5％，碳≤0.014％，氮≤0.004％，铌:0.01～0.05％，硅:0.2～0.6％，铬+钼+0.5锰+0.35镍+0.25铜为11.1～12.2％，碳+氮+0.3硅+锰+1.8铌为0.4～0.8％，余量铁。

Description

400MPa级耐蚀钢筋及其生产方法
本申请要求了申请日为2021年01月15日，申请号为202110051522.4，发明名称为“400MPa级耐蚀钢筋及其生产方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明属于冶金技术领域，涉及一种400MPa级耐蚀钢筋，以及一种400MPa级耐蚀钢筋的生产方法。
背景技术
钢筋混凝土结构是基础设施建设中应用最为广泛的结构形式，钢筋混凝土结构的理论服役年限较长，但在实际工程中却存在钢筋混凝土过早失效的众多案例，不仅增加维护成本，还会造成能源与资源的极大浪费。经调研，沿海的钢筋混凝土结构，由于受到高富含氯离子和硫酸盐、高温高湿等恶劣环境的影响，在投入使用10～15年后，就普遍出现了严重的腐蚀破坏，远未达到设计的理论服役年限。
钢筋混凝土结构中的混凝土属于强碱性环境，于该碱性环境中，钢筋表面会发生钝化而生成一层稳定的金属氧化物钝化膜。在钢筋混凝土结构的实际使用中，钝化膜的溶解与修复理论上处于一种近乎平衡的状态，使得钢筋表面各个位置的电势基本保持一致，从而保证钢筋很难发生腐蚀或者发生腐蚀的速率很低。但当钢筋表面的钝化膜受到外界侵蚀物质的破坏时，例如，海洋环境下，钢筋表面的钝化膜上的活性氯离子达到一定的浓度时，钝化膜溶解与修复失去平衡，钝化膜溶解加快并形成腐蚀坑，导致钢筋基体暴露于侵蚀介质中，最终导致钢筋混凝土结构的失效。
虽然目前通过缓蚀剂、表面防护层、阴极保护、涂层钢筋等手段对延长钢筋混凝土结构的服役年限起到一定的效果，但是，作为钢筋混凝土结构的核心，提高钢筋自身基体的耐腐蚀性能，这才是解决钢筋混凝土结构的腐蚀破坏问题的关键所在。
同时，除了耐腐蚀性能之外，钢筋的力学性能、焊接性能、生产制造成本等方面也是影响钢筋的实际生产和应用的重要方面。例如，不锈钢钢筋是耐腐蚀性能较佳的一种常见钢筋类型，其通过大量添加Cr、Ni、Mo等合金元素，可以使耐腐蚀性能相较于普通碳素钢钢筋得到大幅度提升，腐蚀抗力异常卓越；然而，由于不锈钢钢筋中添加了大量的合金元素，导致其焊接性能非常差，使得实际施工中不锈钢钢筋的焊接施工成本非常高昂，并且还存在钢筋混凝土结构因焊接不良而导致结构不稳定的风险；同时，由于不锈钢钢筋中添加了大量的合金元素，导致其原料成本和生产成本相较于普通钢筋呈倍数增长，进而价格高昂而无法广泛应用，并且也不符合节能降耗的社会需求；另外，关于不锈钢筋和普通钢筋搭接时是否会形成宏电池腐蚀方面，也依然存在争议。
因此，如何同时保证抗腐蚀性能、力学性能、焊接性能以及成本，在耐蚀钢筋的研究方面将是存在显著的社会意义和经济效应的一个重要课题。
发明内容
为解决现有技术中所存在的技术问题，本发明的目的在于提供一种400MPa级耐蚀钢筋，其具有优异的抗腐蚀性能、综合力学性能和焊接性能，并且能够以较低的材料成本和工艺成本予以制得，适于在海洋工程中进行广泛使用。
为实现上述发明目的，一实施方式提供了一种400MPa级耐蚀钢筋，所述钢筋的化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.5％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，且Cr+Mo+0.5Mn+0.35Ni+0.25Cu为11.1～12.2％，C+N+0.3Si+Mn+1.8Nb为0.4～0.8％，余量为Fe及不可避免的杂质。
优选地，所述钢筋的化学成分以质量百分比计还包括：V:0.1～0.15％，Ti:0.01～0.05％，Al:0.01～0.03％，B:0.0005～0.0020％中的任意一种及以上。
进一步地，所述钢筋的微观组织为铁素体和贝氏体，其中铁素体所占比例为28％～40％。
进一步地，所述钢筋在GB/T10561标准下的A类、B类、C类、D类夹杂物均≤1.0级。
进一步地，所述钢筋的屈服强度≥420MPa，抗拉强度≥540MPa，断后伸长率≥18％，最大力总伸长率≥7.5％。
优选地，所述钢筋的公称直径为6～32mm。
优选地，当所述钢筋的公称直径为6～10mm时，所述钢筋设置呈盘卷钢筋；当所述钢筋的公称直径为12～32mm时，所述钢筋设置呈直条钢筋。
进一步地，在周浸腐蚀试验中，所述钢筋的平均失重腐蚀速率为0.05～0.1g/(m 2·h)；在盐雾腐蚀试验中，所述钢筋的平均失重腐蚀速率为0.01～0.04g/(m 2·h)；
在氯离子浓度≥3mol/L的模拟混凝土孔隙液中，所述钢筋的自腐蚀电位为-0.1～-0.15V，极化电阻为2500～3000kΩ/cm 2，自腐蚀电流密度≤0.13μA/cm 2。
优选地，采用工艺路线一和工艺路线二，所述钢筋均可以制备而成；
其中，所述工艺路线一包括依序进行的铁水预脱硫工序、转炉冶炼工序、AOD炉精炼工序、LF炉精炼工序、方坯连铸工序、热连轧工序和控温冷却工序；
所述工艺路线二包括依序进行的铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序、方坯连铸工序、热连轧工序和控温冷却工序。
优选地，所述工艺路线一中：所述转炉冶炼工序的出钢温度为1600-1660℃；所述AOD炉 精炼工序时，向钢水中添加高碳铬铁合金、钼铁合金以对钢水进行初步合金化，还原后进行扒渣，而后添加锰合金，出钢前对出钢所用钢包用氩气吹扫5min以上，出钢过程中向钢水中添加铝锭20kg，出钢温度为1630～1670℃，出钢C含量≤0.01％；所述LF炉精炼工序时，钢水到达LF炉的钢包后，按照每吨钢水添加13～15kg石灰、4.0～6.5kg萤石的方案进行调渣，白渣保持时间≥8min，软搅拌时间8～15min，出钢温度为1600～1620℃；所述方坯连铸工序时，采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为1.2～1.6m/min。
优选地，所述工艺路线二中：所述转炉冶炼工序时，出钢过程中向钢水中添加微碳铬铁合金以对钢水进行初步合金化，出钢温度为1700～1750℃；所述LF炉精炼工序时，LF炉的钢包中以80～160L/min的氩气流量进行全程底吹，出钢温度1560～1600℃；所述RH炉精炼工序时，对RH炉进行抽真空3min之后，开始向RH炉内吹氧，吹氧总量为500～700Nm 3，随后向钢水中添加微碳铬铁合金以对钢水进行合金化，当真空度小于2mbar时进行净循环处理5min以上，出钢温度1560～1600℃，出钢C含量≤0.015％；所述方坯连铸工序时，采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为2.2～2.6m/min。
优选地，所述工艺路线一和所述工艺路线二均为：
所述热连轧工序时，将连铸坯在加热炉中进行加热，加热温度为1100～1200℃，且在炉时间为60～120min，而后轧制成直径为12～32mm的直条螺纹钢筋，开轧温度为1000～1100℃，精轧温度850～950℃；
所述控温冷却工序时，将轧制而成的直条螺纹钢筋在冷床上进行自然冷却，上冷床温度为860～920℃。
优选地，所述工艺路线一和所述工艺路线二均为：所述热连轧工序时，将连铸坯在加热炉中进行加热，加热温度为1080～1130℃，且在炉时间为60～120min，而后轧制成直径为6～10mm的盘卷螺纹钢筋，开轧温度为980～1030℃，精轧温度850～950℃，吐丝温度830～920℃。
优选地，所述工艺路线一和所述工艺路线二均包括于所述控温冷却工序之后依序进行的在线酸洗工序、打包工序；所述在线酸洗工序中，将钢筋依次通过酸洗槽、钝化槽和烘干设备，所述酸洗槽的喷气口环绕所述酸洗槽的中心线分布。
进一步地，当两根所述钢筋采用电渣压力焊连接成焊接试样时，所得焊接试样在拉伸试验中的断裂点形成于两根所述钢筋的母材处。
与现有技术相比，本发明的有益效果包括：
(1)在超低碳设计前提下，合理设计Cr、Mo、Mn、Ni、Cu的各自含量以及关联关系，同时合理设计C、N、Si、Mn、Nb的各自含量以及关联关系，使钢筋具有合理比例的铁素体和贝 氏体两相微观组织，钢筋的整体综合性能优异；具体地，钢筋的力学性能方面：屈服强度≥420MPa、抗拉强度≥540MPa、断后伸长率≥18％、最大力总延伸率≥7.5％；抗腐蚀性能方面：在周浸腐蚀试验和盐雾腐蚀试验中，抗腐蚀性能相对于普通HRB400提高45倍以上，在电化学腐蚀试验中，自腐蚀电位相对于普通HRB400正移幅度超过0.4V、极化电阻远远高于普通HRB400、自腐蚀电流密度相当于普通HRB400的1/65甚至更低；焊接性能方面：易于焊接，焊接点结构牢固而不易断裂，焊接试样在拉伸试验中的断裂点形成于钢筋母材处；
(2)在上述化学成分设计方案的情况下，不仅仅能够实现优异的抗腐蚀性能、综合力学性能和焊接性能，而且合金元素的成本低，节能降耗，并可以通过多条工艺路线制备而成，降低了生产工艺的成本，适宜于实际生产加工，具有更高的社会意义和经济效应。
为解决现有技术中所存在的技术问题，本发明的目的在于提供一种400MPa级耐蚀钢筋的生产方法，其所得钢筋具有优异的抗腐蚀性能、综合力学性能和焊接性能，并且具有较低的材料成本和工艺成本，适于在海洋工程中进行广泛使用。
为实现上述发明目的，一实施方式提供了一种400MPa级耐蚀钢筋的生产方法，所述生产方法包括以下步骤，
(1)炼钢
依次采用铁水预脱硫工序、转炉冶炼工序、AOD炉精炼工序、LF炉精炼工序进行钢水冶炼，或者依次采用铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序进行钢水冶炼，所得钢水连铸成钢坯，所述钢坯的化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.5％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，且Cr+Mo+0.5Mn+0.35Ni+0.25Cu为11.1～12.2％，C+N+0.3Si+Mn+1.8Nb为0.4～0.8％，余量为Fe及不可避免的杂质。
(2)控轧控冷
将步骤1中所得钢坯在加热炉中进行加热，加热温度为1100～1200℃，且在炉时间为60～120min，而后轧制成直径为12～32mm的直条螺纹钢筋，开轧温度为1000～1100℃，精轧温度850～950℃；而后将轧制而成的直条螺纹钢筋在冷床上进行自然冷却，上冷床温度为860～920℃；
或者，将步骤1中所得钢坯在加热炉中进行加热，加热温度为1080～1130℃，且在炉时间为60～120min，而后轧制成直径为6～10mm的盘卷螺纹钢筋，开轧温度为980～1030℃，精轧温度850～950℃，吐丝温度830～920℃；而后将轧制而成的盘卷螺纹钢筋采用延迟型斯太尔摩冷却方式，辊道下方风机全部关闭。
优选地，在步骤1中，所述钢坯的化学成分以质量百分比计还包括：V:0.1～0.15％， Ti:0.01～0.05％，Al:0.01～0.03％，B:0.0005～0.0020％中的任意一种及以上。
优选地，在步骤1中，若依次采用铁水预脱硫工序、转炉冶炼工序、AOD炉精炼工序、LF炉精炼工序进行钢水冶炼，则：所述转炉冶炼工序的出钢温度为1600～1660℃；所述AOD炉精炼工序时，向钢水中添加高碳铬铁合金、钼铁合金以对钢水进行初步合金化，还原后进行扒渣，而后添加锰合金，出钢前对出钢所用钢包用氩气吹扫5min以上，出钢过程中向钢水中添加铝锭20kg，出钢温度为1630～1670℃，出钢C含量≤0.01％；所述LF炉精炼工序时，钢水到达LF炉的钢包后，按照每吨钢水添加13～15kg石灰、4.0～6.5kg萤石的方案进行调渣，白渣保持时间≥8min，软搅拌时间8～15min，出钢温度为1600～1620℃；方坯连铸工序时，采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为1.2～1.6m/min；
而若依次采用铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序进行钢水冶炼，则：所述转炉冶炼工序时，出钢过程中向钢水中添加微碳铬铁合金以对钢水进行初步合金化，出钢温度为1700～1750℃；所述LF炉精炼工序时，LF炉的钢包中以80～160L/min的氩气流量进行全程底吹，出钢温度1560～1600℃；所述RH炉精炼工序时，对RH炉进行抽真空3min之后，开始向RH炉内吹氧，吹氧总量为500～700Nm 3，随后向钢水中添加微碳铬铁合金以对钢水进行合金化，当真空度小于2mbar时进行净循环处理5min以上，出钢温度1560～1600℃，出钢C含量≤0.015％；方坯连铸工序时，采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为2.2～2.6m/min。
优选地，所述生产方法还包括步骤(3)在线酸洗：
将步骤2中所得钢筋依次通过酸洗槽、钝化槽和烘干设备，以进行在线酸洗，所述酸洗槽的喷气口环绕所述酸洗槽的中心线分布；钢筋离开所述烘干设备之后进行打包。
进一步地，采用所述生产方法制备而成的两根钢筋，采用电渣压力焊连接成焊接试样时，所得焊接试样在拉伸试验中的断裂点形成于两根所述钢筋的母材处。
进一步地，采用所述生产方法制备而成的钢筋的微观组织为铁素体和贝氏体，其中铁素体所占比例为28％～40％。
进一步地，采用所述生产方法制备而成的钢筋在GB/T10561标准下的A类、B类、C类、D类夹杂物均≤1.0级。
进一步地，采用所述生产方法制备而成的钢筋的屈服强度≥420MPa，抗拉强度≥540MPa，断后伸长率≥18％，最大力总伸长率≥7.5％。
进一步地，采用所述生产方法制备而成的钢筋，在周浸腐蚀试验中，所述钢筋的平均失重腐蚀速率为0.05～0.1g/(m 2·h)；在盐雾腐蚀试验中，所述钢筋的平均失重腐蚀速率为 0.01～0.04g/(m 2·h)；
在氯离子浓度≥3mol/L的模拟混凝土孔隙液中，所述钢筋的自腐蚀电位为-0.1～-0.15V，极化电阻为2500～3000kΩ/cm 2，自腐蚀电流密度≤0.13μA/cm 2。
与现有技术相比，本发明的有益效果包括：
(1)在超低碳设计前提下，合理设计Cr、Mo、Mn、Ni、Cu的各自含量以及关联关系，同时合理设计C、N、Si、Mn、Nb的各自含量以及关联关系，使钢筋具有合理比例的铁素体和贝氏体两相微观组织，钢筋的整体综合性能优异；具体地，钢筋的力学性能方面：屈服强度≥420MPa、抗拉强度≥540MPa、断后伸长率≥18％、最大力总延伸率≥7.5％；抗腐蚀性能方面：在周浸腐蚀试验和盐雾腐蚀试验中，抗腐蚀性能相对于普通HRB400提高45倍以上，在电化学腐蚀试验中，自腐蚀电位相对于普通HRB400正移幅度超过0.4V、极化电阻远远高于普通HRB400、自腐蚀电流密度相当于普通HRB400的1/65甚至更低；焊接性能方面：易于焊接，焊接点结构牢固而不易断裂，焊接试样在拉伸试验中的断裂点形成于钢筋母材处；
(2)基于上述化学成分设计方案，不仅仅能够实现优异的抗腐蚀性能、综合力学性能和焊接性能，而且合金元素的成本低，节能降耗，并可以通过多条工艺路线制备而成，降低了生产工艺的成本，适宜于实际生产加工，具有更高的社会意义和经济效应；
(3)另外，在上述化学成分设计方案的前提下，结合控轧控冷中的工艺控制，可以进一步优化钢筋的组织、力学性能、抗腐蚀性能和焊接性能，使得钢筋的综合性能得到进一步改善，同时还可以使热连轧过程中的工艺操作简便易控，保证实际生产的工况顺行。
具体实施方式
下面结合具体的实施方式来对本发明的技术方案做进一步的介绍，但要求保护的范围不仅局限于所作的描述。
<第一实施方式>
本实施方式提供了一种耐蚀钢筋，尤其是一种热轧带肋钢筋，其化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.50％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，余量为Fe及不可避免的杂质。
并且，所述钢筋的化学成分中Cr、Mo、Mn、Ni和Cu的质量百分比还满足：11.1％≤Cr+Mo+0.5Mn+0.35Ni+0.25Cu≤12.2％；而C、N、Si、Mn和Nb的质量百分比还满足0.4％≤C+N+0.3Si+Mn+1.8Nb≤0.8％。
其中，所述钢筋中各个化学成分的作用进行说明如下。
Cr：重要的耐蚀元素，可以在钢筋表面形成氧化物钝化膜，从而有效地阻止钢筋氧化、提高钢筋基体的耐腐蚀能力；尤其是与Mo、Ni等元素共同存在时，可以使钢筋获得更优的耐蚀性能并避免点蚀的发生；另外，Cr元素还可以提高钢筋的淬透性；本发明的化学成分设计中，Cr含量控制在9.5～10.4％。
Mo：重要的耐蚀元素，无论是在还原性酸的环境中，还是在强氧化性的盐溶液的环境中，Mo元素的添加都可以使钢筋表面发生钝化，还可以防止钢筋在氯化物溶液中发生点蚀，从而整体上提升钢筋在多种环境下的抗腐蚀性能；再者，Mo元素对珠光体转变的抑制作用非常明显，同时结合碳化物形成元素Cr，可促进贝氏体的生成；另外，Mo元素能促进晶粒细化，提高钢筋的淬透性和热强性；然而，Mo含量过高时，会使钢筋的抗氧化性发生恶化；本发明的化学成分设计中，Mo含量控制在1.0～1.2％。
Mn：固溶强化元素，可以提高盘条的强度，还可以与有害元素S结合以降低钢筋的热脆性；同时也是重要的脱氧剂、脱硫剂、奥氏体形成元素；然而，Mn含量过高时，钢筋的塑性、冲击韧性、焊接性能等均会下降；本发明的化学成分设计中，Mn含量控制在0.3～0.6％。
Ni：重要的耐蚀元素，使钢筋对酸碱环境具有较高的耐腐蚀能力，以及使钢筋在高温下具有较高的防锈能力、耐热能力；同时，Ni元素是奥氏体形成元素，可使钢材具有均匀的奥氏体组织，以改善耐蚀性；本发明的化学成分设计中，Ni含量控制在0.01～1.00％。
Cu：重要的耐蚀元素，有助于提高钢筋的耐蚀性能，然而Cu含量过高时，会导致钢材的塑性降低，引起热轧开裂；本发明的化学成分设计中，Cu含量控制在0.01～0.50％。
C：奥氏体形成元素，控制碳含量维持在铁素体的溶解极限以下，可以提高钢组织结构与成分分布的均匀性，减少钢筋内部各区域之间的电位差，从而降低腐蚀速率，本发明的化学成分设计中，C含量控制在0.014％以下。
N：奥氏体形成元素，若N含量偏高，会降低钢筋的塑性，还会不利于钢筋组织中铁素体和贝氏体的比例控制，本发明的化学成分设计中，N含量控制在0.004％以下。
Nb:微合金强化元素，能够在轧制过程(例如后文所述的热连轧工序)中起到析出强化与细晶强化的作用；然而，Nb含量过高则会导致钢筋的塑性降低、成本增加；本发明的化学成分设计中，Nb含量控制在0.01～0.05％。
Si：固溶强化元素，其固溶于铁素体，能抑制C元素在奥氏体中的扩散、延迟铁素体和珠光体相变，提升钢筋的屈服强度和抗拉强度；然而Si含量过高会降低钢材的塑性，劣化钢筋的焊接性能；本发明的化学成分设计中，Si含量控制在0.2～0.6％。
P：可以提高钢筋的强度和耐蚀性能，但在钢中容易出现偏析，且P含量过高会导致低温时 力学性能较差，本发明的化学成分设计中，P含量控制在0.01～0.03％。
Cr+Mo+0.5Mn+0.35Ni+0.25Cu：对于钢筋的耐蚀性能、塑性以及成本的综合控制非常重要，一方面，使钢筋表面氧化膜具有足够的致密性，提升钢筋基体的耐蚀修复能力，保证钢筋氧化膜与钢筋基体耐蚀性能，再一方面，避免钢筋组织中铁素体的比例偏低，利于控制钢筋的显微组织及比例以提升钢筋的塑性，增大断后伸长率和最大力总伸长率，另一方面，还降低了贵重合金元素的添加，降低成本，促进工程推广、设计及使用，本发明的化学成分设计中，Cr+Mo+0.5Mn+0.35Ni+0.25Cu满足11.1～12.2％。
C+N+0.3Si+Mn+1.8Nb：对于钢筋的强度、塑性等力学性能的综合控制非常重要，一方面，保证合金元素可以充分发挥各自的固溶强化、析出强化及组织强化等方面的作用，提升钢筋的强度，另一方面，避免钢筋组织中铁素体的比例偏低，避免钢筋组织中贝氏体的比例偏高，也即优化钢筋组织中铁素体和贝氏体的各自比例，提升钢筋的塑性，增大断后伸长率和最大力总伸长率，本发明的化学成分设计中，C+N+0.3Si+Mn+1.8Nb满足0.4～0.8％。
综上所述，与现有技术相比，本发明中化学成分的设计中：(1)在超低碳设计前提下，合理设计Cr、Mo、Mn、Ni、Cu的各自含量以及关联关系，同时合理设计C、N、Si、Mn、Nb的各自含量以及关联关系，使钢筋的微观组织为铁素体和贝氏体，其中铁素体所占比例为28％～40％，贝氏体所占比例为60％～72％，并且，钢筋具有优异的抗腐蚀性能、综合力学性能和焊接性能，整体综合性能优异，适用于海洋工程的使用需求；(2)在上述化学成分设计方案的情况下，不仅仅能够实现优异的抗腐蚀性能、综合力学性能和焊接性能，而且合金元素的成本低，节能降耗，并可以通过多条工艺路线制备而成，降低了生产工艺的成本，适宜于实际生产加工，具有更高的社会意义和经济效应。
其中，如前所述，所述钢筋的微观组织为铁素体和贝氏体，其中铁素体所占比例为28％～40％，贝氏体所占比例为60％～72％。如此，微观组织及其铁素体和贝氏体比例，对于所述钢筋的影响进一步体现在两方面：一方面是力学性能，本实施方式中铁素体与贝氏体的比例控制，能够保证适合的屈服强度和良好的延伸率，包括断后伸长率和最大力总伸长率，保证良好的综合力学性能；另一方面是耐蚀性能，保证一定的贝氏体组织比例，可以提升钢筋的耐腐蚀性能。
具体地，在力学性能方面，所述钢筋为400MPa级以上的钢筋，其屈服强度≥420MPa，抗拉强度≥540MPa，断后伸长率≥18％，最大力总伸长率≥7.5％。
另外，所述钢筋在夹杂物方面也得到了极好的控制，具体地，所述钢筋在GB/T10561标准下的A类、B类、C类、D类夹杂物均≤1.0级，如此，可以提高钢筋在低温条件下的韧性，利于保证所述钢筋的力学性能。
进一步地，在耐蚀性能方面，所述钢筋在周浸腐蚀试验和盐雾腐蚀试验中，抗腐蚀性能相对于普通HRB400提高45倍以上。具体地，在周浸腐蚀试验中，所述钢筋的平均失重腐蚀速率为0.05～0.1g/(m 2·h)；在盐雾腐蚀试验中，所述钢筋的平均失重腐蚀速率为0.01～0.04g/(m 2·h)；
在氯离子浓度≥3mol/L的模拟混凝土孔隙液中，所述钢筋的自腐蚀电位为-0.1～-0.15V，极化电阻为2500～3000kΩ/cm 2，自腐蚀电流密度≤0.13μA/cm 2。
其中，所采用的周浸腐蚀试验的具体方法为：将处理后的试样放置周浸试验箱中，试验依照YB/T4367钢筋在氯离子环境中腐蚀试验方法进行，溶液为2.0±0.05(wt％)NaCl，pH为6.5～7.2，溶液温度为45℃±2℃，烘干温度为70℃±10℃，连续试验并获取168h时的平均失重腐蚀速率。
所采用的盐雾腐蚀试验的具体方法为：将处理后的试样放置在盐雾试验箱中，试验依照GB/T10125人造气氛腐蚀试验-盐雾腐蚀试验进行，溶液为2.0±0.05(wt％)NaCl，pH为6.5～7.2，溶液温度为35℃±2℃，连续试验并获取168h时的平均失重腐蚀速率。
而在电化学腐蚀试验中，在氯离子浓度≥3mol/L的模拟混凝土孔隙液腐蚀试验条件下：所述钢筋的自腐蚀电位为-0.1～-0.15V，相对于普通HRB400正移幅度超过0.4V；所述钢筋的极化电阻为2500～3000kΩ/cm 2，远远高于普通HRB400；所述钢筋的自腐蚀电流密度≤0.13μA/cm 2，相当于普通HRB400的1/65甚至更低。
其中，所采用的电化学腐蚀试验的具体方法为：电化学试验依照GB/T24196-2009《金属和合金的腐蚀电化学试验方法恒电位和动电位极化测量导则》执行，采用三电极体系，参比电极为饱和甘汞电极，辅助电极为Pt片，测试溶液为氯离子浓度≥3mol/L的模拟混凝土孔隙液；极化曲线测试扫描范围为相对于试样自腐蚀电位-300～600mV，扫描频率为1mV/s；电化学阻抗测试扫描频率范围为10 -2～10 5Hz，交流激励信号幅值为±5mV。
由此可见，在耐蚀性能方面，所述钢筋具有优越的耐蚀性能，在模拟海水溶液中进行腐蚀性能试验的情况下，各项指标均远优于同等级别的普通螺纹钢。
在焊接性能方面，所述钢筋易于焊接，当两根所述钢筋采用电渣压力焊连接成焊接试样时，焊接点结构牢固而不易断裂，焊接试样在拉伸试验中的断裂点形成于钢筋母材处，而非焊接点位置处。
优选地，本实施方式中，所述钢筋的公称直径为6～32mm。
其中，当所述钢筋的公称直径为6～10mm时，所述钢筋设置呈盘卷钢筋；当所述钢筋的公称直径为12～32mm时，所述钢筋设置呈直条钢筋。如此，可以满足海洋工程中对于钢筋的要求，并且通过直径的设计，也可以提高钢筋结构的综合力学性能及耐蚀性能。
<第二实施方式>
本实施方式提供了一种耐蚀钢筋，具体为一种适用于海洋工程的热轧带肋钢筋，其与前述第一实施方式的区别主要在于：化学成分中进一步增加了V:0.1～0.15％，Ti:0.01～0.05％，Al:0.01～0.03％，B:0.0005～0.0020％中的任意一种及以上，以此来进一步提升钢筋的性能。
具体地，在本实施方式中，所述钢筋的化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.50％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，以及V:0.1～0.15％、Ti:0.01～0.05％、Al:0.01～0.03％、B:0.0005～0.0020％四者中的任意一种及以上，余量为Fe及不可避免的杂质。
并且与第一实施方式同样的，所述钢筋的化学成分中Cr、Mo、Mn、Ni和Cu的质量百分比还满足：11.1％≤Cr+Mo+0.5Mn+0.35Ni+0.25Cu≤12.2％；而C、N、Si、Mn和Nb的质量百分比还满足0.4％≤C+N+0.3Si+Mn+1.8Nb≤0.8％。
其中，所述钢筋中关于Cr、Mo、Mn、Ni、Cu、C、N、Nb、Si、P等元素的作用，以及Cr+Mo+0.5Mn+0.35Ni+0.25Cu和C+N+0.3Si+Mn+1.8Nb的设计效果，与前述第一实施方式相同，不再多加赘述。下面对本实施方式中可选元素V、Ti、Al和B的作用进行说明。
V：微合金强化元素，能够在轧制过程(比如后文的热连轧工序)中析出V(C,N)化合物，具有一定的析出强化作用，同时阻止奥氏体和铁素体晶粒长大，具有细晶强化作用；然而，V含量过高，则会降低钢筋的塑性，并且增加成本，本发明的化学成分设计中，V含量控制在0.1～0.15％。
Ti：与C元素的亲和力比Cr大，由此可以避免析出碳化铬而出现晶界贫铬，从而有效防止晶间腐蚀；并且，适量添加Ti可在钢板中形成细小弥散分布的TiOx和TiN；然而，Ti含量过高，则会增加钢液的黏度，不利于钢水的冶炼，同时还会导致所形成的TiOx尺寸粗大，恶化钢板的韧性；本发明的化学成分设计中，Ti含量控制在0.01～0.05％。
Al：常用的脱氧剂，可以提高钢筋基体的电极电位，提高耐蚀性；并且可以阻止奥氏体晶粒生长，提高钢筋强度；然而，Al含量过多，则有可能导致钢中氧化物增多，会对钢筋的焊接性不利；本发明的化学成分设计中，Al含量控制在0.01～0.03％。
B：强化元素，对提高钢筋强度具有显著作用，但B含量过高对于晶间耐蚀性能的提高不利；本发明的化学成分设计中，B含量控制在0.0005～0.0020％。
本实施方式中，基于V、Ti、Al和B任一种或以上的选择性添加，可以使得所述钢筋在性能方面在第一实施方式的基础上得到进一步地改善，该钢筋具有更加优异的抗腐蚀性能、力学强度、塑性和焊接性能，不仅便于工程施工，而且在海洋工程中使用时可以具有更长的理论服务年限。
<第三实施方式>
本实施方式提供了一种耐蚀钢筋的生产方法，其既可以用于前述第一实施方式的耐蚀钢筋的生产制备，又可以用于前述第二实施方式的耐蚀钢筋的生产制备。
在本实施方式中，所述生产方法的工艺路线包括依序进行的铁水预脱硫工序、转炉冶炼工序、AOD炉精炼工序、LF炉精炼工序、方坯连铸工序、热连轧工序、控温冷却工序和打包工序。下面按照步骤顺序对所述生产方法进行详细介绍。
(1)炼钢步骤
在该步骤中，依次采用铁水预脱硫工序、转炉冶炼工序、AOD炉精炼工序、LF炉精炼工序进行钢水冶炼，所得钢水采用所述方坯连铸工序连铸成钢坯。
可以理解的，当采用所述生产方法用于前述第一实施方式的耐蚀钢筋的制备时，该步骤中所得钢坯的化学成分与第一实施方式的钢筋的化学成分相一致，也即所得钢坯的化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.50％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，且Cr+Mo+0.5Mn+0.35Ni+0.25Cu为11.1～12.2％，C+N+0.3Si+Mn+1.8Nb为0.4～0.8％，余量为Fe及不可避免的杂质；类似的，当采用所述生产方法用于前述第二实施方式的耐蚀钢筋的制备时，该步骤中所得钢坯的化学成分与第二实施方式的钢筋的化学成分相一致，也即所得钢坯的化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.50％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，以及V:0.1～0.15％、Ti:0.01～0.05％、Al:0.01～0.03％、B:0.0005～0.0020％四者中的任意一种及以上，且Cr+Mo+0.5Mn+0.35Ni+0.25Cu为11.1～12.2％，C+N+0.3Si+Mn+1.8Nb为0.4～0.8％，余量为Fe及不可避免的杂质。
进一步地，所述转炉冶炼工序的出钢温度为1600～1660℃，保证脱C及脱P效果，利于后续合金化。
所述AOD炉精炼工序时，综合考虑，向钢水中添加成本较低的高碳铬铁合金、钼铁合金以对钢水进行初步合金化，还原后进行扒渣，降低P等杂质元素含量，而后添加锰合金，脱氧的同时完成初步合金化，出钢前对出钢所用钢包用氩气吹扫5min以上，减少钢水二次氧化，出钢过程中向钢水中添加铝锭20kg，出钢温度为1630～1670℃，出钢C含量≤0.01％，保证了钢水脱碳效果及生产节奏。
所述LF炉精炼工序时，钢水到达LF炉的钢包后，按照每吨钢水添加13～15kg石灰、4.0～6.5kg萤石的方案进行调渣，白渣保持时间≥8min，软搅拌时间8～15min，出钢温度为1600～1620℃， 逐步完成钢水脱氧脱硫。
所述方坯连铸工序时，将所述LF炉精炼工序的出钢钢水连铸成方坯，其中采用无碳保护渣或者超低碳保护渣，防止钢水增碳，连铸温度1520～1560℃，连铸过程中拉速为1.2～1.6m/min，保证连续浇注。
(2)控轧控冷
在该步骤中，将步骤1中所得钢坯通过热连轧工序轧制成公称直径为6～32mm的钢筋，而后进行控温冷却工序。而根据钢筋的公称直径的不同，该步骤的具体工艺方案不同。
具体地，针对公称直径为12～32mm的钢筋而言，在该步骤中：所述热连轧工序时，将步骤1中所得钢坯在加热炉中进行加热，加热温度为1100～1200℃，且在炉时间为60～120min，合金元素充分回溶，有利于合金元素强化效果发挥，而后轧制成直径为12～32mm的直条螺纹钢筋，开轧温度为1000～1100℃，精轧温度850～950℃，使奥氏体晶粒保持在一定尺寸；而后所述控温冷却工序时，将轧制而成的直条螺纹钢筋在冷床上进行自然冷却，上冷床温度为860～920℃，保证后续铁素体及珠光体尺寸及比例控制。
针对公称直径为6～10mm的钢筋而言，在该步骤中：所述热连轧工序时，将步骤1中所得钢坯在加热炉中进行加热，加热温度为1080～1130℃，利于合金元素充分回溶，且在炉时间为60～120min，而后轧制成直径为6～10mm的盘卷螺纹钢筋，开轧温度为980～1030℃，精轧温度850～950℃，吐丝温度830～920℃，使奥氏体晶粒保持在一定尺寸；而后所述控温冷却工序时，将轧制而成的盘卷螺纹钢筋采用延迟型斯太尔摩方式冷却，辊道下方风机全部关闭，铁素体及珠光体相变在辊道上完成。
(3)打包
将步骤2中经过冷却的钢筋进行打包，以待运输并投入工程应用。
由此，相较于现有技术，本实施方式的生产方法的有益效果在于：
(1)其化学成分的设计，在超低碳设计前提下，合理设计Cr、Mo、Mn、Ni、Cu的各自含量以及关联关系，同时合理设计C、N、Si、Mn、Nb的各自含量以及关联关系，使得制备而成的钢筋的微观组织为铁素体和贝氏体，其中铁素体所占比例为28％～40％，贝氏体所占比例为60％～72％，并且，钢筋具有优异的抗腐蚀性能、综合力学性能和焊接性能，整体综合性能优异，适用于海洋工程的使用需求；
(2)在上述化学成分设计方案的情况下，工艺路线合理，尤其是控轧控冷中的工艺控制合理，进一步优化所得钢筋的整体综合性能，轧制过程中无裂纹缺陷，而且合金元素的成本低，节能降耗，并降低了生产工艺的成本，适宜于实际生产加工，工艺操作简便易控，保证实际生产的 工况顺行，具有更高的社会意义和经济效应。
<第四实施方式>
本实施方式提供了一种耐蚀钢筋的生产方法，其既可以用于前述第一实施方式的耐蚀钢筋的生产制备，又可以用于前述第二实施方式的耐蚀钢筋的生产制备。
在本实施方式中，所述生产方法的工艺路线包括依序进行的铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序、方坯连铸工序、热连轧工序、控温冷却工序和打包工序。也即，本实施方式与前述第三实施方式的不同仅在于：铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序以及方坯连铸工序，也即炼钢步骤。下面仅就该炼钢步骤对本实施方式的所述生产方法进行详细介绍。
(1)炼钢步骤
在该步骤中，依次采用铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序进行钢水冶炼，所得钢水采用所述方坯连铸工序连铸成钢坯。
可以理解的，当采用所述生产方法用于前述第一实施方式的耐蚀钢筋的制备时，该步骤中所得钢坯的化学成分与第一实施方式的钢筋的化学成分相一致，也即所得钢坯的化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.50％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，且Cr+Mo+0.5Mn+0.35Ni+0.25Cu为11.1～12.2％，C+N+0.3Si+Mn+1.8Nb为0.4～0.8％，余量为Fe及不可避免的杂质；类似的，当采用所述生产方法用于前述第二实施方式的耐蚀钢筋的制备时，该步骤中所得钢坯的化学成分与第二实施方式的钢筋的化学成分相一致，也即所得钢坯的化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.50％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，以及V:0.1～0.15％、Ti:0.01～0.05％、Al:0.01～0.03％、B:0.0005～0.0020％四者中的任意一种及以上，且Cr+Mo+0.5Mn+0.35Ni+0.25Cu为11.1～12.2％，C+N+0.3Si+Mn+1.8Nb为0.4～0.8％，余量为Fe及不可避免的杂质。
进一步地，所述转炉冶炼工序时，出钢过程中向钢水中添加微碳铬铁合金以对钢水进行初步合金化，尽可能从合金加入角度控制钢水中C含量，提高效率，出钢温度为1700～1750℃，保证脱磷效果，且为后续冶炼做好准备。
所述LF炉精炼工序时，LF炉的钢包中以80～160L/min的氩气流量进行全程底吹，出钢温度1560～1600℃，保证钢包内合金溶解及均匀化，利于生产节奏控制。
所述RH炉精炼工序时，对RH炉进行抽真空3min之后，开始向RH炉内吹氧，吹氧总量 为500～700Nm 3，随后向钢水中添加微碳铬铁合金以对钢水进行合金化，分步完成Cr合金化，同时减少钢水增碳，当真空度小于2mbar时进行净循环处理5min以上，出钢温度1560～1600℃，出钢C含量≤0.015％，保证脱碳效果。
所述方坯连铸工序时，将所述LF炉精炼工序的出钢钢水连铸成方坯，其中采用无碳保护渣或者超低碳保护渣，防止钢水增碳，连铸温度1520～1560℃，连铸过程中拉速为2.2～2.6m/min，利于连续浇注。
如前所述，步骤2的控轧控冷步骤、步骤3的打包工序均与前述第三实施方式相同，不再赘述。
由此，相较于现有技术，本实施方式的生产方法的有益效果在于：
(1)其化学成分的设计，在超低碳设计前提下，合理设计Cr、Mo、Mn、Ni、Cu的各自含量以及关联关系，同时合理设计C、N、Si、Mn、Nb的各自含量以及关联关系，使得制备而成的钢筋的微观组织为铁素体和贝氏体，其中铁素体所占比例为28％～40％，贝氏体所占比例为60％～72％，并且，钢筋具有优异的抗腐蚀性能、综合力学性能和焊接性能，整体综合性能优异，适用于海洋工程的使用需求；
(2)在上述化学成分设计方案的情况下，工艺路线合理，尤其是控轧控冷中的工艺控制合理，进一步优化所得钢筋的整体综合性能，轧制过程中无裂纹缺陷，而且合金元素的成本低，节能降耗，并降低了生产工艺的成本，适宜于实际生产加工，工艺操作简便易控，保证实际生产的工况顺行，具有更高的社会意义和经济效应。
<第五实施方式>
本实施方式提供了一种耐蚀钢筋的生产方法，其工艺路线包括依序进行的铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序、方坯连铸工序、热连轧工序、控温冷却工序、在线酸洗工序和打包工序。
而本实施方式中，自所述铁水预脱硫工序至所述控温冷却工序具体可采用前述第三实施方式予以实施，也可以采用前述第四实施方式予以实施，也即本实施方式是在前述第三实施方式或第四实施方式的基础上，在打包工序之前增加了在线酸洗工序，下面仅就该在线酸洗工序予以介绍，其余不再赘述。
具体地，所述在线酸洗工序中，也即在控温冷却工序之后且打包工序之前，将钢筋依次通过酸洗槽、钝化槽和烘干设备，以实现钢筋的在线酸洗。其中，所述酸洗槽的喷气口环绕所述酸洗槽的中心线分布，以增强酸洗的效果。
下面提供本发明的实施例1～16，来对本发明进一步说明。可以理解的是，以下仅为本发明 的部分优选的实施例，而并非本发明的全部实施情况，在前述实施方式的基础上进行的其它实施例，未脱离本发明的技艺宗旨。
首先，实施例1～16和对比例1～4均提供了一种钢筋，所述钢筋的化学成分如表1所示。其中，实施例12按照本发明的前述第一实施方式予以实施，其余实施例则按照本发明的前述第二实施方式予以实施，对比例1～4不满足本发明的任一实施方式。
[表1]
Figure PCTCN2021086677-appb-000001
Figure PCTCN2021086677-appb-000002
实施例1～8的生产方法，采用包括依序进行的铁水预脱硫工序、转炉冶炼工序、AOD炉精炼工序、LF炉精炼工序、方坯连铸工序、热连轧工序、控温冷却工序和在线酸洗工序的工艺路线，下面对各个工序予以介绍。
(1)铁水预脱硫工序：对铁水进行预脱硫；
(2)转炉冶炼工序：出钢温度为1600～1660℃；
(3)AOD炉精炼工序：向钢水中添加高碳铬铁合金、钼铁合金以对钢水进行初步合金化，还原后进行扒渣，而后添加锰合金，出钢前对出钢所用钢包用氩气吹扫5min以上，出钢过程中向钢水中添加铝锭20kg，出钢温度为1630～1670℃，出钢C含量≤0.010％；
(4)LF炉精炼工序：钢水到达LF炉的钢包后，按照每吨钢水添加13～15kg石灰、4.0～6.5kg萤石的方案进行调渣，白渣保持时间≥8min，软搅拌时间8～15min，出钢温度为1600～1620℃；
(5)方坯连铸工序：将所述LF炉精炼工序的出钢钢水连铸成方坯，其中采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为1.2～1.6m/min；
(6)热连轧工序：实施例1～4中，将方坯在加热炉中进行加热，加热温度为1100～1200℃，且在炉时间为60～120min，而后轧制成直径为12～32mm的直条螺纹钢筋，开轧温度为1000～1100℃，精轧温度850～950℃；实施例5～8中，将方坯在加热炉中进行加热，加热温度为1080～1130℃，且在炉时间为60～120min，而后轧制成直径为6～10mm的盘卷螺纹钢筋，开轧温度为980～1030℃，精轧温度850～950℃，吐丝温度830～920℃；
(7)控温冷却工序：实施例1～4中，将轧制而成的直条螺纹钢筋在冷床上进行自然冷却，上冷床温度为860～920℃；实施例5～8中，将轧制而成的盘卷螺纹钢筋采用延迟型斯太尔摩方式冷却，辊道下方风机全部关闭；
(8)在线酸洗工序：将钢筋依次通过酸洗槽、钝化槽和烘干设备，以实现钢筋的在线酸洗，其中，所述酸洗槽的喷气口环绕所述酸洗槽的中心线分布，之后进行打包。
实施例9～16的生产方法，采用包括依序进行的铁水预脱硫工序、转炉冶炼工序、LF炉精炼 工序、RH炉精炼工序、方坯连铸工序、热连轧工序、控温冷却工序和在线酸洗工序的工艺路线，下面对各个工序予以介绍。
(1)铁水预脱硫工序：对铁水进行预脱硫，脱硫后S≤0.001％，扒渣率≥95％；
(2)转炉冶炼工序：出钢过程中向钢水中添加微碳铬铁合金以对钢水进行初步合金化，出钢温度为1700～1750℃；
(3)LF炉精炼工序；LF炉的钢包中以80～160L/min的氩气流量进行全程底吹，出钢温度1560～1600℃；
(4)RH炉精炼工序：对RH炉进行抽真空3min之后，开始向RH炉内吹氧，吹氧总量为500～700Nm 3，随后向钢水中添加微碳铬铁合金以对钢水进行合金化，当真空度小于2mbar时进行净循环处理5min以上，出钢温度1560～1600℃，出钢C含量≤0.015％；
(5)方坯连铸工序：将所述LF炉精炼工序的出钢钢水连铸成方坯，其中采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为2.2～2.6m/min；
(6)热连轧工序：实施例9～12中，将方坯在加热炉中进行加热，加热温度为1100～1200℃，且在炉时间为60～120min，而后轧制成直径为12～32mm的直条螺纹钢筋，开轧温度为1000～1100℃，精轧温度850～950℃；实施例13～16中，将方坯在加热炉中进行加热，加热温度为1080～1130℃，且在炉时间为60～120min，而后轧制成直径为6～10mm的盘卷螺纹钢筋，开轧温度为980～1030℃，精轧温度850～950℃，吐丝温度830～920℃；
(7)控温冷却工序：实施例9～12中，将轧制而成的直条螺纹钢筋在冷床上进行自然冷却，上冷床温度为860～920℃；实施例13～16中，将轧制而成的盘卷螺纹钢筋采用延迟型斯太尔摩方式冷却，辊道下方风机全部关闭；
(8)在线酸洗工序：将钢筋依次通过酸洗槽、钝化槽和烘干设备，以实现钢筋的在线酸洗，其中，所述酸洗槽的喷气口环绕所述酸洗槽的中心线分布，之后进行打包。
对比例1～4所采用的生产方法为传统的转炉冶炼、方坯连铸、热连轧、冷床冷却的工艺路线，其中热连轧工序时，在加热炉中的加热温度为1210～1290℃，开轧温度为1090～1170℃，上冷床温度≥1100℃，在冷床上自然冷却。
对实施例1～16和对比例1～4的钢筋，按照相同的测试方法进行取样并检测力学性能，各个实施例和对比例的力学性能如表2所示。
从表2中可以看出，实施例1～16在力学性能方面明显地优于对比例1～4，其满足400MPa级别抗震钢筋的要求，并且屈服强度≥420MPa，抗拉强度≥540MPa，断后伸长率≥18％，最大力总伸长率≥7.5％。
[表2]
编号 屈服强度(MPa) 抗拉强度(MPa) 断后延伸率A(％) 最大力总伸长率Agt(％)
实施例1 474 638 25 8.1
实施例2 467 604 20 11.1
实施例3 459 596 20 10.6
实施例4 450 584 21 10.5
实施例5 445 582 21 10.1
实施例6 445 579 20 9.9
实施例7 445 575 20 9.6
实施例8 441 564 21 8.2
实施例9 420 555 18 7.6
实施例10 492 627 24 15.9
实施例11 480 626 24 14.8
实施例12 478 621 22 14.2
实施例13 466 615 22 13.9
实施例14 463 613 22 12.6
实施例15 461 612 20 12.1
实施例16 455 610 20 11.3
对比例1 427 567 19 7.1
对比例2 451 555 15 6.9
对比例3 448 578 15 8.9
对比例4 469 594 18 12.3
对实施例1～16和对比例1～4的钢筋，按照相同的方法进行周浸腐蚀试验、盐雾腐蚀试验和电化学腐蚀试验，测试结果如表3所示。
其中，所采用的周浸腐蚀试验的具体方法为：将处理后的试样放置周浸试验箱中，试验依照YB/T4367钢筋在氯离子环境中腐蚀试验方法进行，溶液为2.0±0.05(wt％)NaCl，pH为6.5～7.2，溶液温度为45℃±2℃，烘干温度为70℃±10℃，连续试验并获取168h时的平均失重腐蚀速率。
所采用的盐雾腐蚀试验的具体方法为：将处理后的试样放置在盐雾试验箱中，试验依照GB/T10125人造气氛腐蚀试验-盐雾腐蚀试验进行，溶液为2.0±0.05(wt％)NaCl，pH为6.5～7.2，溶液温度为35℃±2℃，连续试验并获取168h时的平均失重腐蚀速率。
所采用的电化学腐蚀试验的具体方法为：电化学试验依照GB/T24196-2009《金属和合金的腐蚀电化学试验方法恒电位和动电位极化测量导则》执行，采用三电极体系，参比电极为饱和甘汞电极，辅助电极为Pt片，测试溶液为氯离子浓度≥3mol/L的模拟混凝土孔隙液；极化曲线测试扫描范围为相对于试样自腐蚀电位-300～600mV，扫描频率为1mV/s；电化学阻抗测试扫描频率范围为10 -2～10 5Hz，交流激励信号幅值为±5mV。
[表3]
Figure PCTCN2021086677-appb-000003
从表3中可以看出，实施例1～16在耐蚀性能方面大幅度优于对比例1～4，其在周浸腐蚀试验中，所述钢筋的平均失重腐蚀速率为0.05～0.1g/(m 2·h)；在盐雾腐蚀试验中，所述钢筋的平均失重腐蚀速率为0.01～0.04g/(m 2·h)，抗腐蚀性能相对于普通HRB400提高45倍以上；在电化学腐蚀试验中，在氯离子浓度≥3mol/L的模拟混凝土孔隙液中：所述钢筋的自腐蚀电位为-0.1～-0.15V，相对于普通HRB400正移幅度超过0.4V；所述钢筋的极化电阻为2500～3000kΩ/cm 2，远远高于普通HRB400；所述钢筋的自腐蚀电流密度≤0.13μA/cm 2，相当于普通HRB400的1/65甚至更低。
再者，对实施例1～16的钢筋，取样进行夹杂物检测和微观组织检测，在GB/T10561标准下的A类、B类、C类、D类夹杂物均≤1.0级，而微观组织为为铁素体和贝氏体，其中铁素体所占比例为28％～40％，贝氏体所占比例为60％～72％。
另外，对实施例1～16的钢筋，分别取样并采用电渣压力焊进行焊接试验，并对焊接试样按照GBT228.1-2010金属材料拉伸试验第1部分的室温试验方法标准进行拉伸试验，焊接试样在拉伸试验中的断裂点形成于钢筋母材处，而非焊接点位置处，可见所得钢筋的焊接性能优异。

Claims (20)

  1. 一种400MPa级耐蚀钢筋，其特征在于，所述钢筋的化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.5％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，且Cr+Mo+0.5Mn+0.35Ni+0.25Cu为11.1～12.2％，C+N+0.3Si+Mn+1.8Nb为0.4～0.8％，余量为Fe及不可避免的杂质。
  2. 根据权利要求1所述的400MPa级耐蚀钢筋，其特征在于，所述钢筋的化学成分以质量百分比计还包括：V:0.1～0.15％，Ti:0.01～0.05％，Al:0.01～0.03％，B:0.0005～0.0020％中的任意一种及以上。
  3. 根据权利要求1所述的400MPa级耐蚀钢筋，其特征在于，所述钢筋的微观组织为铁素体和贝氏体，其中铁素体所占比例为28％～40％。
  4. 根据权利要求1所述的400MPa级耐蚀钢筋，其特征在于，所述钢筋在GB/T10561标准下的A类、B类、C类、D类夹杂物均≤1.0级。
  5. 根据权利要求1所述的400MPa级耐蚀钢筋，其特征在于，所述钢筋的屈服强度≥420MPa，抗拉强度≥540MPa，断后伸长率≥18％，最大力总伸长率≥7.5％。
  6. 根据权利要求1所述的400MPa级耐蚀钢筋，其特征在于，所述钢筋的公称直径为6～32mm。
  7. 根据权利要求6所述的400MPa级耐蚀钢筋，其特征在于，当所述钢筋的公称直径为6～10mm时，所述钢筋设置呈盘卷钢筋；当所述钢筋的公称直径为12～32mm时，所述钢筋设置呈直条钢筋。
  8. 根据权利要求1所述的400MPa级耐蚀钢筋，其特征在于，在周浸腐蚀试验中，所述钢筋的平均失重腐蚀速率为0.05～0.1g/(m 2·h)；在盐雾腐蚀试验中，所述钢筋的平均失重腐蚀速率为0.01～0.04g/(m 2·h)；
    在氯离子浓度≥3mol/L的模拟混凝土孔隙液中，所述钢筋的自腐蚀电位为-0.1～-0.15V，极化电阻为2500～3000kΩ/cm 2，自腐蚀电流密度≤0.13μA/cm 2。
  9. 根据权利要求1所述的400MPa级耐蚀钢筋，其特征在于，采用工艺路线一和工艺路线二，所述钢筋均可以制备而成；
    其中，所述工艺路线一包括依序进行的铁水预脱硫工序、转炉冶炼工序、AOD炉精炼工序、LF炉精炼工序、方坯连铸工序、热连轧工序和控温冷却工序；
    所述工艺路线二包括依序进行的铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序、方坯连铸工序、热连轧工序和控温冷却工序。
  10. 根据权利要求9所述的400MPa级耐蚀钢筋，其特征在于，所述工艺路线一中：
    所述转炉冶炼工序的出钢温度为1600-1660℃；
    所述AOD炉精炼工序时，向钢水中添加高碳铬铁合金、钼铁合金以对钢水进行初步合金化，还原后进行扒渣，而后添加锰合金，出钢前对出钢所用钢包用氩气吹扫5min以上，出钢过程中向钢水中添加铝锭20kg，出钢温度为1630～1670℃，出钢C含量≤0.010％；
    所述LF炉精炼工序时，钢水到达LF炉的钢包后，按照每吨钢水添加13～15kg石灰、4.0～6.5kg萤石的方案进行调渣，白渣保持时间≥8min，软搅拌时间8～15min，出钢温度为1600～1620℃；
    所述方坯连铸工序时，采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为1.2～1.6m/min。
  11. 根据权利要求9所述的400MPa级耐蚀钢筋，其特征在于，所述工艺路线二中：
    所述转炉冶炼工序时，出钢过程中向钢水中添加微碳铬铁合金以对钢水进行初步合金化，出钢温度为1700～1750℃；
    所述LF炉精炼工序时，LF炉的钢包中以80～160L/min的氩气流量进行全程底吹，出钢温度1560～1600℃；
    所述RH炉精炼工序时，对RH炉进行抽真空3min之后，开始向RH炉内吹氧，吹氧总量为500～700Nm 3，随后向钢水中添加微碳铬铁合金以对钢水进行合金化，当真空度小于2mbar时进行净循环处理5min以上，出钢温度1560～1600℃，出钢C含量≤0.015％；
    所述方坯连铸工序时，采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为2.2～2.6m/min。
  12. 根据权利要求9所述的400MPa级耐蚀钢筋，其特征在于，所述工艺路线一和所述工艺路线二均为：
    所述热连轧工序时，将连铸坯在加热炉中进行加热，加热温度为1100～1200℃，且在炉时间为60～120min，而后轧制成直径为12～32mm的直条螺纹钢筋，开轧温度为1000～1100℃，精轧温度850～950℃；
    所述控温冷却工序时，将轧制而成的直条螺纹钢筋在冷床上进行自然冷却，上冷床温度为860～920℃。
  13. 根据权利要求9所述的400MPa级耐蚀钢筋，其特征在于，所述工艺路线一和所述工艺路线二均为：
    所述热连轧工序时，将连铸坯在加热炉中进行加热，加热温度为1080～1130℃，且在炉时间为60～120min，而后轧制成直径为6～10mm的盘卷螺纹钢筋，开轧温度为980～1030℃，精轧温 度850～950℃，吐丝温度830～920℃。
  14. 根据权利要求9所述的400MPa级耐蚀钢筋，其特征在于，所述工艺路线一和所述工艺路线二均包括于所述控温冷却工序之后依序进行的在线酸洗工序、打包工序；
    所述在线酸洗工序中，将钢筋依次通过酸洗槽、钝化槽和烘干设备，所述酸洗槽的喷气口环绕所述酸洗槽的中心线分布。
  15. 根据权利要求1所述的400MPa级耐蚀钢筋，其特征在于，当两根所述钢筋采用电渣压力焊连接成焊接试样时，所得焊接试样在拉伸试验中的断裂点形成于两根所述钢筋的母材处。
  16. 一种400MPa级耐蚀钢筋的生产方法，其特征在于，包括以下步骤，
    (1)炼钢
    依次采用铁水预脱硫工序、转炉冶炼工序、AOD炉精炼工序、LF炉精炼工序进行钢水冶炼，或者依次采用铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序进行钢水冶炼，所得钢水连铸成钢坯，所述钢坯的化学成分以质量百分比计包括：Cr:9.5～10.4％，Mo:1.0～1.2％，Mn:0.3～0.6％，Ni:0.01～1.00％，Cu:0.01～0.5％，C≤0.014％，N≤0.004％，Nb:0.01～0.05％，Si:0.2～0.6％，S≤0.004％，O≤0.003％，As≤0.01％，P:0.01～0.03％，且Cr+Mo+0.5Mn+0.35Ni+0.25Cu为11.1～12.2％，C+N+0.3Si+Mn+1.8Nb为0.4～0.8％，余量为Fe及不可避免的杂质。
    (2)控轧控冷
    将步骤1中所得钢坯在加热炉中进行加热，加热温度为1100～1200℃，且在炉时间为60～120min，而后轧制成直径为12～32mm的直条螺纹钢筋，开轧温度为1000～1100℃，精轧温度850～950℃；而后将轧制而成的直条螺纹钢筋在冷床上进行自然冷却，上冷床温度为860～920℃；
    或者，将步骤1中所得钢坯在加热炉中进行加热，加热温度为1080～1130℃，且在炉时间为60～120min，而后轧制成直径为6～10mm的盘卷螺纹钢筋，开轧温度为980～1030℃，精轧温度850～950℃，吐丝温度830～920℃；而后将轧制而成的盘卷螺纹钢筋采用斯太尔摩冷却，辊道下方风机全部关闭。
  17. 根据权利要求16所述的400MPa级耐蚀钢筋的生产方法，其特征在于，在步骤1中，所述钢坯的化学成分以质量百分比计还包括：V:0.1～0.15％，Ti:0.01～0.05％，Al:0.01～0.03％，B:0.0005～0.0020％中的任意一种及以上。
  18. 根据权利要求16所述的400MPa级耐蚀钢筋的生产方法，其特征在于，在步骤1中，若依次采用铁水预脱硫工序、转炉冶炼工序、AOD炉精炼工序、LF炉精炼工序进行钢水冶炼，则：所述转炉冶炼工序的出钢温度为1600-1660℃；所述AOD炉精炼工序时，向钢水中添加高碳铬铁合金、钼铁合金以对钢水进行初步合金化，还原后进行扒渣，而后添加锰合金，出钢前对出钢 所用钢包用氩气吹扫5min以上，出钢过程中向钢水中添加铝锭20kg，出钢温度为1630～1670℃，出钢C含量≤0.01％；所述LF炉精炼工序时，钢水到达LF炉的钢包后，按照每吨钢水添加13～15kg石灰、4.0～6.5kg萤石的方案进行调渣，白渣保持时间≥8min，软搅拌时间8～15min，出钢温度为1600～1620℃；方坯连铸工序时，采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为1.2～1.6m/min；
    而若依次采用铁水预脱硫工序、转炉冶炼工序、LF炉精炼工序、RH炉精炼工序进行钢水冶炼，则：所述转炉冶炼工序时，出钢过程中向钢水中添加微碳铬铁合金以对钢水进行初步合金化，出钢温度为1700～1750℃；所述LF炉精炼工序时，LF炉的钢包中以80～160L/min的氩气流量进行全程底吹，出钢温度1560～1600℃；所述RH炉精炼工序时，对RH炉进行抽真空3min之后，开始向RH炉内吹氧，吹氧总量为500～700Nm 3，随后向钢水中添加微碳铬铁合金以对钢水进行合金化，当真空度小于2mbar时进行净循环处理5min以上，出钢温度1560～1600℃，出钢C含量≤0.015％；方坯连铸工序时，采用无碳保护渣或者超低碳保护渣，连铸温度1520～1560℃，连铸过程中拉速为2.2～2.6m/min。
  19. 根据权利要求16所述的400MPa级耐蚀钢筋的生产方法，其特征在于，还包括步骤，
    (3)在线酸洗
    将步骤2中所得钢筋依次通过酸洗槽、钝化槽和烘干设备，以进行在线酸洗，所述酸洗槽的喷气口环绕所述酸洗槽的中心线分布；钢筋离开所述烘干设备之后进行打包。
  20. 根据权利要求16所述的400MPa级耐蚀钢筋的生产方法，其特征在于，采用所述生产方法制备而成的两根钢筋，采用电渣压力焊连接成焊接试样时，所得焊接试样在拉伸试验中的断裂点形成于两根所述钢筋的母材处。
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