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CN-121976123-A - 2400 MPa-level hot-rolled wire rod for stranded wire and manufacturing method thereof

CN121976123ACN 121976123 ACN121976123 ACN 121976123ACN-121976123-A

Abstract

The invention relates to a 2400 MPa-level hot rolled wire rod for a stranded wire and a manufacturing method thereof, wherein after Cr-Mo-V-Al chemical components are adopted to roll and spin the wire rod as the wire rod, the wire rod is subjected to online molten salt rapid quenching isothermal treatment, so that the wire rod is firstly subjected to front-stage molten salt treatment and enters a sorbite phase region from an austenitic state to form a tissue mainly comprising sorbite tissues, then is subjected to rear-stage molten salt treatment, the circulation quantity of the molten salt is reduced, the unconverted residual austenite is promoted to be continuously converted into sorbite, the isothermal tempering is carried out, part of sorbite sheets are promoted to fuse, and finally, the hot rolled wire rod is slowly cooled by a roller way to prepare a hot rolled wire rod with a microstructure comprising tempered sorbite, tempered ferrite and fused sorbite, so that the strong plasticity matching and the tissue uniformity of the hot rolled wire rod can be improved, the tensile strength is 1575-1625 MPa, the section shrinkage rate is 32% -37%, and the ultra-high strength stranded wire is conveniently produced by off-line heat treatment, and the yield of the stranded wire is improved.

Inventors

  • Peng Mengdu
  • HU JUNHUI
  • CHEN YUANQING
  • WANG MIAO
  • WANG LUYI
  • SHI TONGTONG
  • CAO LEI
  • Rao Zicai
  • ZHANG YEFEI

Assignees

  • 江苏永钢集团有限公司
  • 联峰钢铁（张家港）有限公司

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. The manufacturing method of the hot-rolled wire rod for 2400 MPa-level stranded wire is characterized by comprising the following steps of: The wire rod is rolled according to chemical components of a hot rolled wire rod, the chemical components and the mass percent of the hot rolled wire rod comprise ：C：0.92％~0.97％、Si：0.88％~1.10％、Mn：0.66％~0.83％、Cr：0.37％~0.57％、V：0.025％~0.037％、Mo：0.25％~0.45％、Al：0.15％~0.35％、P≤0.015％、S≤0.015％, and the balance of Fe and unavoidable impurities, after the wire rod is spun into the wire rod according to the spinning temperature of more than or equal to 925 ℃, the wire rod is subjected to on-line molten salt rapid quenching isothermal treatment, so that the wire rod firstly enters a sorbite phase region from an austenitic state through the treatment of a front-stage molten salt and the cooling speed of more than or equal to 32 ℃ to form a tissue mainly comprising sorbite tissue, then the later-stage molten salt treatment is carried out, the circulation quantity of the molten salt is reduced, the unconverted residual austenite is promoted to be continuously converted into sorbite, isothermal tempering is carried out, partial sorbite sheet layer fusing is promoted, and finally the hot rolled wire rod with a mixed tissue comprising tempered sorbite, ferrite and fused sorbite is manufactured through the slow cooling of a roller way.
  2. 2. The method for manufacturing a hot rolled wire rod for 2400 MPa-level strands according to claim 1, wherein the soaking temperature of the heating furnace is 1160-1220 ℃ and the furnace time is 180-300 min before the rolling.
  3. 3. The method for manufacturing a hot rolled wire rod for 2400 MPa-level strands according to claim 1, wherein the initial rolling temperature is controlled to 1050 to 1100 ℃, the final rolling temperature is controlled to 925 to 965 ℃, and the final rolling reduction is controlled to 24 to 29%.
  4. 4. The method for producing a hot rolled wire rod for 2400 MPa-grade wire according to claim 1, wherein the wire laying temperature is controlled to 925 to 950 ℃.
  5. 5. The method for manufacturing the hot rolled wire rod for 2400 MPa-level stranded wires according to claim 1, wherein the molten salt temperature of the front-stage molten salt treatment is 525-565 ℃, the treatment time is 20-40 s, the molten salt temperature of the rear-stage molten salt treatment is 545-578 ℃, and the treatment time is 160-350 s.
  6. 6. The method for manufacturing the hot rolled wire rod for 2400 MPa-level stranded wires, which is characterized in that the circulation amount of molten salt in the front-stage molten salt treatment is 440-640 t/h, the temperature rise of the molten salt is less than or equal to 8 ℃, the circulation amount of the molten salt in the rear-stage molten salt treatment is 285-370 t/h, and the temperature rise of the molten salt is less than or equal to 3 ℃.
  7. 7. The method for manufacturing a hot rolled wire rod for 2400 MPa-level strands according to claim 5, wherein the roller way slow cooling control wire rod is cooled to 280 ℃ or below at a slow cooling rate of 0.3-0.6 ℃ per second for coil collection.
  8. 8. A hot rolled wire rod for 2400 MPa-level stranded wire, characterized in that the hot rolled wire rod is manufactured by the manufacturing method of 2400 MPa-level stranded wire according to any one of claims 1 to 7.
  9. 9. The 2400 MPa-level hot-rolled wire rod for a stranded wire according to claim 8, wherein the volume percentage of tempered sorbite is not less than 65%, the lamellar spacing is 70-115 nm, the volume percentage of tempered ferrite is not more than 5%, the volume percentage of fused sorbite is not less than 20%, the mesh carbide grade of the hot-rolled wire rod is 0, and the same-circle difference of mechanical properties is not more than 50MPa.
  10. 10. The 2400 MPa-grade hot-rolled wire rod for a stranded wire according to claim 8, wherein the hot-rolled wire rod has a diameter of 5.5-16 mm, a tensile strength of 1575-1625 MPa, and a reduction of area of 32% -37%.

Description

2400 MPa-level hot-rolled wire rod for stranded wire and manufacturing method thereof Technical Field The invention belongs to the technical field of hot rolled wire rods, and particularly relates to a 2400 MPa-level hot rolled wire rod for a stranded wire and a manufacturing method thereof. Background Along with the development and progress of the railway system prestress technology, the conventional 1960 MPa-level prestress steel strand is difficult to meet the increasingly developed market demand, but meanwhile, the hot-rolled wire rod is used as a base material for production, the production cost is increased, the energy consumption of off-line heat treatment production is improved and the like due to the limitation of base material components, tissues and performances, and the improvement of the strength grade of the strand is also caused, so that the problems of increasing the production cost, the off-line heat treatment production energy consumption and the like are often irresistible, and therefore, the hot-rolled wire rod for 2400 MPa-level strand needs to be developed based on the requirement of prestress box girders and the like on the further improvement of the strength of the steel strand, the off-line heat treatment is not needed, the strength grade of the steel strand can be improved, the purposes of saving materials and energy and reducing the production cost are achieved, and the development and market use demands of the steel industry are met. The existing hot-rolled wire rod for high-strength stranded wires generally adopts a high-carbon combined microalloy component system, and the manufacturing of 2400 MPa-level hot-rolled wire rod for stranded wires has the following technical bottlenecks: 1. The prior hot-rolled wire rod for the high-strength stranded wire is generally produced by adopting the strong cooling control and cooling process of a stelmor air-cooled wire after rolling and wire spinning, so as to promote the refinement of pearlite sheets and improve the temperature control instability, but is limited by the segregation of high carbon components and the highest cooling capacity of the air-cooled wire, carbide is easy to be continuously precipitated along grain boundaries to form a split matrix and deteriorate the netlike carbide of the plastic toughness of the wire rod, in order to improve the cooling speed, in the prior art, online water bath cooling is adopted, for example, the manufacturing method of the wire rod and the steel strand for the anti-stress corrosion ultrahigh-strength steel stranded wire disclosed by the patent CN114369760B adopts the component design of C-Si-Mn-Cr-V-B, and adopts the online water bath cooling and water-out slow cooling process after being combined with rolling and wire spinning to obtain the wire rod, but is similar to the air-cooled wire, a large amount of bubbles are formed on the surface after the high-cooled wire is subjected to improve the air-cooled strength, so that uneven cooling and unstable can cause uneven cooling, uneven precipitation of micro-alloy carbide is easy to be caused, the high-carbon components are easy to be lengthened, the temperature control and the quality of the wire rod is easy to be affected by the gradient of the gradient cooling, the gradient of the wire rod is easy to be further affected by the gradient cooling, the crack is difficult to be further affected by the gradient of the gradient wire rod, the crack is difficult to be produced, and the crack is difficult to be further affected by the crack, and the quality is difficult to be deformed and has the crack and has the poor quality and has the quality. 2. In order to improve the wire rod strengthening performance, in the prior art, online salt bath treatment is adopted, for example, 2400-2460 MPa-level stress corrosion resistant prestress wire rods, steel strands and production methods disclosed by CN120400685A are adopted, C-Si-Mn-Cr-V-Nb components are combined with online salt bath isothermal treatment after rolling and wire spinning, and slow cooling treatment at the temperature of not higher than 0.2 ℃ per second is adopted to obtain sorbite structure wire rods, but the addition of various microalloy components can cause higher material cost, the precipitation risk of netlike carbide and martensite abnormal structures is still limited by the wire rod components and one-stage salt bath treatment, meanwhile, the online aging treatment of slow cooling at a low cooling speed is also required to be matched with the increase of the coarsening risk of cementite, the production efficiency is influenced, the low-temperature rolling is required to be matched, the rolling deformation resistance is further increased with the increase of alloy content, the load of a rolling line is increased, and the rolling efficiency is influenced. Disclosure of Invention The invention aims to solve at least one of the technical problems to a certain extent, and provides a 2400 M