CN-121976124-A - 2430 MPa-level high-strength multiphase hot rolled wire rod for stranded wire and manufacturing method thereof

CN121976124ACN 121976124 ACN121976124 ACN 121976124ACN-121976124-A

Abstract

The invention relates to a 2430 MPa-level high-strength complex-phase hot rolled wire rod and a manufacturing method thereof, which adopts Mo-Nb-V high-carbon chemical composition rolling spinning to form the wire rod, and then carries out on-line molten salt weak quenching isothermal annealing treatment, so that the wire rod is firstly subjected to front-stage molten salt treatment and rapidly cooled, enters a bainite phase region from an austenite state, promotes the transformation of partial austenite into bainite, then carries out post-stage molten salt treatment, improves the molten salt temperature, reduces the circulation quantity of molten salt, promotes the decomposition and transformation of unconverted residual austenite into sorbite and carries out isothermal tempering, and finally carries out roller way slow cooling to prepare the hot rolled wire rod with a complex-phase structure formed by tempered bainite and tempered sorbite, thereby effectively inhibiting abnormal structure and realizing complex-phase structure regulation, achieving 1592-164 MPa of tensile strength, 27% -32% of section shrinkage, material cost, production efficiency and energy consumption, and being convenient for off-line heat treatment production of ultra-high-strength stranded wires.

Inventors

Peng Mengdu
HU JUNHUI
CHEN YUANQING
WANG MIAO
Rao Zicai
ZHANG YEFEI
SHI TONGTONG

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 high-strength multiphase hot rolled wire rod for 2430 MPa-level stranded wires is characterized by comprising the following steps of: The method comprises the steps of rolling a hot rolled wire rod according to chemical components of the hot rolled wire rod, wherein the chemical components and the mass percent of the hot rolled wire rod comprise ：C：0.92％~0.97％、Si：0.78％~0.98％、Mn：0.74％~0.92％、Cr：0.50％~0.70％、Mo：0.35％~0.55％、Nb：0.022％~0.042％、V：0.028％~0.048％、P≤0.014％、S≤0.014％, and the balance of Fe and unavoidable impurities, spinning the wire rod according to the spinning temperature of more than or equal to 897 ℃ to obtain the wire rod, performing on-line molten salt weak quenching isothermal annealing treatment to enable the wire rod to enter a bainite phase region from an austenite state through front-stage molten salt treatment and cooling at a cooling speed of more than or equal to 32 ℃ so as to promote partial austenite to be converted into bainite, performing back-stage molten salt treatment, improving the molten salt temperature, reducing the circulating amount of the molten salt, promoting the decomposition and conversion of unconverted residual austenite into sorbite, performing isothermal tempering, and finally performing roller way cooling to obtain the hot rolled wire rod with a microstructure comprising tempered bainite and tempered sorbite and a complex phase structure.
2. The method for manufacturing a high-strength composite hot-rolled wire rod for 2430 MPa-level stranded wires according to claim 1, wherein the soaking temperature of a heating furnace is controlled to be 1195-1245 ℃ and the furnace time is 165-265 min before rolling.
3. The method for manufacturing a high-strength, multi-phase hot rolled wire rod for a 2430 MPa-grade stranded wire according to claim 1, wherein the initial rolling temperature is controlled to 1038 to 1078 ℃, the initial rolling reduction is controlled to 36 to 41%, the final rolling temperature is controlled to 908 to 948 ℃, and the final rolling reduction is controlled to 21 to 26%.
4. The method for manufacturing a high-strength composite hot-rolled wire rod for 2430 MPa-level stranded wires according to claim 1, wherein the wire laying temperature is controlled to be 897-937 ℃ during wire laying.
5. The method for manufacturing the high-strength multiphase hot rolled wire rod for 2430 MPa-level stranded wires, which is characterized in that the molten salt temperature of the front-stage molten salt treatment is 408-438 ℃, the treatment time is 8-26s, the molten salt temperature of the rear-stage molten salt treatment is 573-600 ℃, and the treatment time is 183-293 s.
6. The method for manufacturing the high-strength multiphase hot rolled wire rod for 2430 MPa-level stranded wires, which is characterized in that the circulation amount of molten salt in the front-stage molten salt treatment is 580-880t/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 410-510 t/h, and the temperature rise of the molten salt is less than or equal to 3 ℃.
7. The method for manufacturing a high-strength composite hot-rolled wire rod for 2430 MPa-level stranded wires according to claim 5, wherein the roller way slow cooling control wire rod is cooled to below 280 ℃ at a slow cooling speed of 0.5-0.8 ℃ per second for collecting coils.
8. A high-strength multiphase hot rolled wire rod for 2430 MPa-level stranded wire, characterized in that the hot rolled wire rod is manufactured by the manufacturing method of 2430 MPa-level stranded wire of any one of claims 1 to 7.
9. The 2430 MPa-level stranded wire high-strength complex-phase hot-rolled wire rod of claim 8, wherein the volume percentage of tempered bainite is 6% -14%, the volume percentage of tempered sorbite is 86% -94%, the lamellar spacing of tempered sorbite is 65-110 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 53MPa.
10. The high-strength, multi-phase hot rolled wire rod for 2430 MPa-level stranded wire according to claim 8, wherein the hot rolled wire rod has a diameter of 7-15 mm, a tensile strength of 1592-1641 MPa, and a reduction of area of 27-32%.

Description

2430 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 2430 MPa-level high-strength multiphase hot rolled wire rod for a stranded wire and a manufacturing method thereof. Background With the industrial upgrading of the high-strength and special-strength steel industry, the twisted wire is gradually developed to 2200MPa ultra-high strength and higher strength, the light weight of an engineering structure is facilitated, the durability and service safety of the engineering structure are improved, the strength twisted wire is formed by taking a hot-rolled wire rod as a base material and processing through procedures such as drawing, twisting and the like, but the strength twisted wire is limited by the limitation of a rolling and cooling control production line of an existing steel mill, the hot-rolled wire rod for the high-strength twisted wire is mainly in a pearlite type, the alloy cost is high, the abnormal structure control difficulty is high, the ultra-high-strength twisted wire rod is produced by carrying out one additional heat treatment on the hot-rolled wire rod after the hot rolling is taken off the wire rod, the use requirement can be met, the user cost and the energy consumption are also greatly improved, and therefore, the hot-rolled wire rod for the 2430MPa twisted wire rod and the manufacturing method thereof are required to be developed, the tissue toughness is regulated on line, and the requirements of development and market use in 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 2430 MPa-level stranded wire also has the following technical bottlenecks: 1. Carbon is used as a low-price and high-efficiency strengthening element, in order to improve the strength of the wire rod, the carbon content is further improved to more than 0.9%, on one hand, the carbon is limited by the highest cooling capacity limit of a stelmor air cooling line, secondary cementite is easily precipitated at a crystal boundary to form a reticular carbide, the uniformity of a structure and the toughness of plastic are influenced, the subsequent drawing wire breakage rate is increased, in order to reduce the influence of the reticular carbide as much as possible, the wire throwing temperature and the air cooling strength are improved, the air cooling temperature control instability leads to further increase of the cooling speed difference of a wire rod lap joint, a non-lap joint, an air-receiving surface, a leeward surface and a core part, the quenching property of the wire rod and the segregation of alloy elements influence, uncontrollable martensite and other brittle structures are easily formed at local supercooling positions in the wire rod, the tissue brittleness is increased after phase transition is remained in the tissue, the risk of coil collection embrittlement is generated, and the subsequent wire breakage risk of wire making is aggravated; while the wire rod for the stress corrosion resistant ultra-high strength steel strand and the manufacturing method of the steel strand, disclosed in the patent CN114369760B, adopt an online water bath cooling and water outlet slow cooling process, the cooling speed of the wire rod can be improved, but a large amount of bubbles adhere to the surface of the wire rod during cooling to interfere heat transfer and still influence the uniformity of the structure and the control of abnormal structure, on the other hand, the length of a Steyr air cooling wire is limited and the cooling control capacity is limited under a high silicon component system, the phase transformation incubation period of the structure is longer, coarse pearlite is easily formed at the core part of the wire rod under continuous cooling, the strength of the wire rod is lost, microalloy components are added in the wire rod, but alloy carbides with uneven thickness are easily separated out under the conditions that the wire rod passes through a high temperature interval and the air cooling wire is unstable to influence the nailing effect, too much addition of expensive microalloy components can also cause the overhigh material cost, and the wire rod is in a low temperature state after the phase transformation incubation, abnormal tissues and residual stress are left in the tissues, so that the fluctuation of mechanical properties of the finished product is large, the plasticity is insufficient, and the production bottleneck of off-line heat treatment is difficult to break through. 2. In order to improve the wire rod strong plasticity, an online salt bath treatment process is proposed in the prior art, for example, 2400-