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CN-122013052-A - 2460 MPa-level high-strength multiphase hot rolled wire rod for stranded wire and manufacturing method thereof

CN122013052ACN 122013052 ACN122013052 ACN 122013052ACN-122013052-A

Abstract

The invention relates to a 2460 MPa-level high-strength multiphase hot rolled wire rod and a manufacturing method thereof, which adopts Cr-V high-carbon component rolling spinning to form the wire rod, and then carries out online molten salt rapid quenching isothermal toughening treatment, so that the wire rod is firstly subjected to front-stage molten salt treatment and rapidly cooled, enters a bainitic phase region from an austenite state, promotes the transformation of partial austenite into bainite, then is subjected to rear-stage molten salt treatment, improves the molten salt temperature, reduces the circulating amount of the molten salt, promotes the decomposition and transformation of unconverted residual austenite into sorbite and carries out isothermal tempering, and finally is subjected to roller way slow cooling to prepare the hot rolled wire rod with a microstructure comprising tempered bainite and tempered sorbite, thereby simplifying the component system, realizing the regulation and online toughening of the multiphase structure, achieving the tensile strength of 1606-1666 MPa, and the section shrinkage of 26% -32%, and facilitating the production efficiency of the ultra-high-strength high-efficiency stranded wire rod without offline heat treatment.

Inventors

  • Peng Mengdu
  • HU JUNHUI
  • CHEN YUANQING

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
20260512
Application Date
20260407

Claims (10)

  1. 1. The manufacturing method of the high-strength multiphase hot rolled wire rod for 2460 MPa-level stranded wires is characterized by comprising the following steps of: The wire rod is rolled according to chemical components of a hot rolled wire rod, wherein the chemical components and the mass percentages of the hot rolled wire rod comprise, by weight, 0.93% -0.98% of C, 0.77% -0.97% of Si, 0.77% -0.97% of Mn, 0.59% -0.72% of Cr, 0.049% -0.065% of V, less than or equal to 0.014% of P, less than or equal to 0.014% of S and unavoidable impurities, the wire rod is spun into the wire rod according to the spinning temperature of more than or equal to 900 ℃, and then is subjected to online molten salt rapid quenching isothermal tempering treatment, so that the wire rod is firstly subjected to the front-stage molten salt treatment and enters a bainitic phase region according to the cooling speed of more than or equal to 35 ℃ from an austenitic state, the transformation of part of austenite into bainitic phase region is promoted, then the rear-stage molten salt treatment is carried out, the molten salt circulation quantity is increased, the unconverted residual austenite is promoted to be transformed into sorbite, isothermal tempering is carried out, and finally the wire rod with a microstructure comprising a hot rolled complex phase structure of the tempered and tempered sorbite is obtained through roller way annealing.
  2. 2. The method for manufacturing a high-strength composite hot-rolled wire rod for 2460 MPa-level stranded wires according to claim 1, wherein the soaking temperature of a heating furnace is controlled to be 1192-1242 ℃ and the furnace time is 160-260 min before rolling.
  3. 3. The method for manufacturing a high-strength, multi-phase hot rolled wire rod for a 2460 MPa-level stranded wire according to claim 1, wherein the initial rolling temperature is controlled to 1040 to 1080 ℃, the final rolling temperature is controlled to 915 to 955 ℃, and the final rolling reduction is controlled to 23 to 28%.
  4. 4. The method for manufacturing a high-strength composite hot-rolled wire rod for 2460 MPa-level stranded wires according to claim 1, wherein the wire laying temperature is controlled to be 900-940 ℃ during wire laying.
  5. 5. The method for manufacturing the high-strength multiphase hot rolled wire rod for 2460 MPa-level stranded wires, which is characterized in that the molten salt temperature of the front-stage molten salt treatment is 440-470 ℃, the treatment time is 12-32 s, the molten salt temperature of the rear-stage molten salt treatment is 580-610 ℃ and the treatment time is 295-403 s.
  6. 6. The method for manufacturing the high-strength multiphase hot rolled wire rod for 2460 MPa-level stranded wires, which is characterized in that the circulation amount of molten salt in the front-stage molten salt treatment is 645-900 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 515-315 t/h, and the temperature rise of the molten salt is less than or equal to 3 ℃.
  7. 7. The method for manufacturing a high-strength composite hot-rolled wire rod for 2460 MPa-level stranded wires according to claim 5, wherein the roller way slow cooling control wire rod is cooled to below 290 ℃ at a slow cooling speed of 0.45-0.75 ℃ per second for collecting coils.
  8. 8. A high-strength multiphase hot rolled wire rod for 2460 MPa-level stranded wire, characterized in that the hot rolled wire rod is manufactured by the manufacturing method of 2460 MPa-level stranded wire according to any one of claims 1 to 7.
  9. 9. The 2460 MPa-level stranded wire high-strength complex-phase hot-rolled wire rod of claim 8, wherein the volume percentage of tempered bainite is 15% -23%, the volume percentage of tempered sorbite is 77% -85%, the lamellar spacing of tempered sorbite is 85-130 nm, the mesh carbide level of the hot-rolled wire rod is 0, and the same-circle difference of mechanical properties is less than or equal to 54MPa.
  10. 10. The high-strength, multi-phase hot rolled wire rod for 2460 MPa-level stranded wire according to claim 8, wherein the hot rolled wire rod has a diameter of 8-15 mm, a tensile strength of 1606-1666 MPa, and a reduction of area of 26-32%.

Description

2460 MPa-level high-strength multiphase 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 2460 MPa-level high-strength multiphase hot rolled wire rod for a stranded wire and a manufacturing method thereof. Background The hot-rolled wire rod is used as a base material and is processed through working procedures such as drawing, twisting and the like, the development of the ultra-high strength wire rod is beneficial to the promotion of the light weight and long-service-life upgrade of the fields such as transportation, engineering and the like, but the hot-rolled wire rod for the high-strength wire rod is generally in a pearlite type in view of the capability of the conventional steel mill for rolling and cold control production line, the initial strength is insufficient, the drawing hardening capability is limited, and the network carbide and the brittle structure are more difficult to control along with the addition of carbon and alloy components in the steel, the subsequent drawing and wire breakage risks are greatly increased, so the ultra-high strength wire rod of 2200MPa grade is rarely developed, the ultra-high strength wire rod of 2400MPa grade or above is freshly developed, and the hot-rolled wire rod needs to be heated and austenitized again in cooperation with the offline heat treatment, but the production energy consumption of the hot-rolled wire rod is high, the flow length and the cost is also caused. Along with the development of the excellent steel industry to green low carbon and high quality, a 2460MPa hot rolled wire rod for stranded wires and a manufacturing method thereof need to be developed, so that a component system can be simplified, the tissue toughness can be regulated and controlled on line, and additional heat treatment is not needed, so that the development and market use requirements of the steel industry are met. The existing wire rod for the high-strength stranded wire is generally produced by adopting a high-carbon high-silicon microalloy component system and combining a post-rolling stelmor air-cooled line, but the hot-rolled wire rod for manufacturing 2460 MPa-level stranded wire also has the following technical bottlenecks: 1. In order to improve the strength of steel, the contents of elements such as C, si, mn and the like are increased, and alloy elements such as V, B, nb and the like are added, but on one hand, the segregation of carbon and alloy elements is aggravated when a steel billet is solidified, and is limited by the highest cooling capacity of a stelmor air cooling line, a central carbon enrichment region can separate out a netty carbide hard and brittle phase, so that the plastic toughness performance of the wire rod is influenced and becomes a crack source in a cold drawing process, and in order to reduce the influence of the netty carbide as much as possible and promote the reduction of the lamellar spacing of pearlite sheets so as to pull up the strength of a matrix, the air cooling strength is improved, the temperature difference between an air receiving surface and an air receiving surface is further increased, the surface to a core part is increased, the alloy carbide is separated out unevenly, the improvement on the toughness is limited, and the water bath cooling is adopted to improve the cooling speed of the wire rod, but a large amount of bubbles are generated to adhere to the surface of the wire rod so that the wire rod is influenced by the quenching property of the wire rod, uncontrollable bainite, martensite and other hard and brittle tissues are easy to be partially supercooled to form in the subsequent continuous cooling, so that the hard tissues cannot be toughened in the process, so that the wire rod plasticity is rapidly reduced and the mechanical performance is further increased, and the risk of wire breakage is further increased; on the other hand, under a high-silicon chromium-containing component system, phase-change inoculation is prolonged, the length of a stelmor air cooling line is limited, the minimum cooling capacity is limited, the time of wire rods after phase-change inoculation is short, full phase change is difficult, coarse lamellar pearlite is easily formed on a core part, strength is reduced, the wire rods under continuous cooling are in a low-temperature state after phase-change inoculation, thermal stress and tissue stress accumulated by phase change are remained in a matrix, the final strength and plastic toughness performance are insufficient, the production bottleneck without off-line heat treatment is difficult to break through, and the stranded wire target strength is difficult to reach. 2. In order to improve the wire rod strength and plasticity performance, an online salt bath treatment process is proposed in the prior art, for example, 2400-2460 MPa-level stress corrosion resistan