CN-121976125-A - 2460 MPa-level hot-rolled wire rod for stranded wire and manufacturing method thereof

CN121976125ACN 121976125 ACN121976125 ACN 121976125ACN-121976125-A

Abstract

The invention relates to a 2460 MPa-level hot rolled wire rod for a stranded wire and a manufacturing method thereof, wherein after high-carbon chemical components of high Si-Al are adopted to roll and spin the wire rod as the wire rod, the wire rod is subjected to on-line molten salt isothermal annealing treatment, the wire rod is firstly subjected to front-stage molten salt treatment and rapidly cooled, enters a sorbite phase region from an austenite state to form a tissue mainly comprising sorbite tissue, is subjected to rear-stage molten salt treatment, the circulation amount of the molten salt is reduced, the non-converted retained austenite is promoted to be continuously converted into sorbite and is subjected to isothermal tempering, part of sorbite sheets are promoted to fuse, and finally, the hot rolled wire rod of a mixed tissue formed by micro-structures comprising tempered sorbite, tempered ferrite and fused sorbite is slowly cooled through a roller way, so that the material cost can be controlled, the abnormal tissue can be effectively restrained, the tensile strength is 1595-1645 MPa, the section shrinkage rate is 32-37%, the production efficiency and the energy consumption are taken into account, and the ultra-high strength stranded wire is produced through off-line 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: 20260505
Application Date: 20260407

Claims (10)

1. The manufacturing method of the hot-rolled wire rod for the 2460 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：0.94％~0.99％、Si：0.88％~1.08％、Mn：0.83％~1.03％、Cr：0.44％~0.64％、V：0.045％~0.054％、Al：0.38％~0.49％、P≤0.014％、S≤0.014％, and the balance of Fe and unavoidable impurities, the wire rod is subjected to on-line molten salt isothermal annealing treatment after being spun into the wire rod according to the spinning temperature of more than or equal to 890 ℃, the wire rod is firstly subjected to front-stage molten salt treatment and is cooled at the cooling speed of more than or equal to 33 ℃ per second, enters a sorbite phase region from an austenitic state to form a tissue mainly comprising sorbite tissue, is subjected to rear-stage molten salt treatment, reduces the circulation quantity of molten salt, promotes the unconverted residual austenite to be continuously converted into sorbite, is subjected to isothermal tempering, promotes part of sorbite sheet layers to fuse, and is finally subjected to roller way slow cooling to prepare the hot rolled wire rod of a mixed tissue consisting of tempered sorbite, ferrite and fused sorbite.
2. The method for manufacturing a hot rolled wire rod for 2460 MPa-level stranded wire according to claim 1, wherein a soaking temperature of a heating furnace is controlled to be 1200-1250 ℃ before rolling, and a furnace time is controlled to be 180-270 min.
3. The method for manufacturing a hot rolled wire rod for 2460 MPa-level stranded wire according to claim 1, wherein the initial rolling temperature is 1035 to 1085 ℃, the final rolling temperature is 900 to 950 ℃, and the final rolling reduction is 23 to 28%.
4. The method for producing a hot rolled wire rod for 2460MPa grade strands according to claim 1, wherein the spinning temperature is controlled to 890 to 940 ℃.
5. The method for manufacturing the hot rolled wire rod for the 2460 MPa-level stranded wire according to claim 1, wherein the molten salt temperature of the front-stage molten salt treatment is 566-596 ℃, the treatment time is 222-322 s, the molten salt temperature of the rear-stage molten salt treatment is 580-596 ℃, and the treatment time is 105-205 s.
6. The method for manufacturing the hot rolled wire rod for the 2460 MPa-level stranded wire, which is characterized in that the circulation amount of molten salt in the front-stage molten salt treatment is 520-720 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 280-480 t/h, and the temperature rise of the molten salt is less than or equal to 3 ℃.
7. The method for manufacturing a 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 280 ℃ or below at a slow cooling speed of 0.4-0.7 ℃ per second for coil collection.
8. A hot-rolled wire rod for 2460 MPa-level stranded wire, characterized in that the hot-rolled wire rod is produced by the method for producing a hot-rolled wire rod for 2460 MPa-level stranded wire according to any one of claims 1 to 7.
9. The 2460 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 54%, the lamellar spacing is 65-115 nm, the volume percentage of tempered ferrite is not more than 7%, the volume percentage of fused sorbite is not less than 29%, the mesh carbide grade of the hot-rolled wire rod is 0, and the same-circle difference of mechanical properties is not more than 51MPa.
10. The hot rolled wire rod for 2460 MPa-level stranded wire of claim 8, wherein the hot rolled wire rod has a diameter of 5.5-15 mm, a tensile strength of 1595-1645 MPa, and a reduction of area of 32-37%.

Description

2460 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 2460 MPa-level hot rolled wire rod for stranded wires and a manufacturing method thereof. Background With the development of the super-strength steel industry, especially in the stranded wire field, the super-strength stranded wire has become a development focus in favor of the light weight of the structure, the prolonged service life of the structure, the reduction of maintenance cost and the upgrading of the power-assisted industry of engineering application, but the steel stranded wire is formed by taking a hot-rolled wire rod as a base material and processing the hot-rolled wire rod through processes such as drawing, twisting and the like, the strength grade of the super-strength stranded wire is limited by the structural performance of the raw material hot-rolled wire rod, the raw material is often developed on the basis of adding reinforcing elements such as C, mn, cr and the like, and the excessively high reinforcing elements are extremely easy to cause the rapid increase of the probability of the generation of the deterioration structures such as reticular carbide, martensite, bainite and the like in the hot-rolled wire rod of the lower line, the increase of the duty ratio, the stable production of the hot-rolled wire rod and the development of a downstream stranded wire rod plant are limited, so that the hot-rolled wire rod for 2460MPa grade stranded wire rod and the manufacturing method thereof are required to be developed, and the strong plastic matching of the hot-rolled wire rod can be effectively controlled, so as to meet the development and market use requirements of the steel industry. Although some wire rods for ultra-high strength stranded wires are proposed in the prior art, the following technical bottlenecks exist in manufacturing hot rolled wire rods for 2460 MPa-level stranded wires: 1. The existing hot rolled wire rod for the high-strength stranded wire generally adopts a high-carbon component system, is combined with the stelmor air-cooled wire controlled cooling production after spinning, so that the strength grade is further improved, and along with the addition of strengthening elements, on one hand, the highest cooling capacity limitation of the stelmor air-cooled wire is limited, cementite is more easily separated out along grain boundaries in the process of controlled cooling of the high-carbon steel wire rod to form a fracture matrix and network carbides with adverse plasticity and torsion performance, meanwhile, the segregation of a continuous casting blank can lead to enrichment of C, mn and Cr in local areas, mn and Cr can reduce the martensitic transformation point, the influence of the network carbides is reduced to the greatest extent, the temperature instability and the influence of a cooling mode are controlled after the air-cooled strength is improved by promoting the refinement of pearlite sheets, the temperature difference between the wind-affected surface and the wind-cooled surface is further increased, the local or segregation area is easy to form brittle tissues such as bainite and martensite, the uniformity of the tissues is reduced, the brittleness and the fluctuation of mechanical performance of the wire rod is increased, the cooling speed of the wire rod can be improved by water bath cooling, but a large amount of bubbles can be generated to be attached to the surface influence of the wire rod, the surface heat transfer is difficult to effectively inhibit the subsequent drawing of the abnormal wire rod structure; on the other hand, the length and the minimum cooling capacity of the stelmor air cooling line are limited, the time of the wire rod passing through a phase transition temperature interval is limited, the wire rod is difficult to fully change phase, the core of the wire rod is easy to form a coarse lamellar structure, although microalloy components are added, uneven precipitation thickness leads to limited strength improvement and higher material cost, meanwhile, cr element can refine pearlite lamellar, but can improve the hardness and brittleness of cementite, the wire rod is in a low-temperature state after phase transition inoculation under continuous cooling, the stress in the phase transition process is remained in a tissue, the plastic toughness of the hot-rolled wire rod is insufficient, the risk of broken wire drawing is increased, and additional heat treatment is needed to be matched before the wire twisting factory draws after the wire twisting factory is disconnected, so that the energy consumption and the cost are increased, and the production efficiency is reduced. 2. In order to improve the strength and plasticity of stranded wire rods, salt bath treatment is proposed in the prior art, for example, 2400-2460 MPa-level stress corrosion r