CN-122013054-A - 15Mm large-specification 2000 MPa-level prestressed steel wire rod and preparation method thereof

CN122013054ACN 122013054 ACN122013054 ACN 122013054ACN-122013054-A

Abstract

The invention discloses a 15mm large-specification 2000 MPa-level prestressed steel wire rod and a preparation method thereof, and belongs to the technical field of metal material preparation and metal pressure processing. The invention aims to develop a 15mm large-size high-performance prestressed steel wire rod of a novel component system and a matched production process thereof, wherein the tensile strength of the wire rod is more than or equal to 1200MPa, the reduction of area (after aging) is more than or equal to 30%, and the product is used as a large-size high-strength high-speed rail plate prestressed steel wire, a 1960-2000 MPa-level high-performance prestressed steel wire and a steel strand. The invention meets the severe requirements of large-sized high-performance prestressed materials of modern important engineering on the wire rod performance through the technological processes of molten iron pretreatment, converter smelting, LF refining, RH refining, square billet continuous casting, casting blank slow cooling pit slow cooling, casting blank heating, high-pressure water descaling, controlled rolling and controlled cooling, PF line heat preservation channel slow cooling and a complete and controllable production technological system thereof.

Inventors

MOU LIJUN
QIU XUE
JIANG YANJU
LI WENWU
XU TAIXU
LIU ZHIPU
JIANG YUNAN
Tian Weiyang
ZHANG HONGLIANG
HE YINGLI

Assignees

本钢板材股份有限公司
本溪北营钢铁（集团）股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260410

Claims (10)

1. A15 mm large-specification 2000 MPa-level wire rod for prestressed steel is characterized in that the specific components of the wire rod for prestressed steel are ：C：0.81%~0.85%,Si：0.20%~0.30%,Mn：0.75%~0.82%,P：≤0.018%,S：≤0.015%,Cr：0.25%~0.30%,V：0.020%~0.050%,Nb：0.010%~0.015%,Al：≤0.030%,Ti：≤0.0015%,Ni：≤0.10%,Cu：≤0.20%,O：≤0.0040%,N：≤0.0050%,H：≤0.00015%, percent by weight and the balance of Fe and unavoidable impurities.
2. The wire rod for prestressed steel according to claim 1, wherein the specific components of said wire rod for prestressed steel are ：C：0.81%~0.85%,Si：0.20%~0.30%,Mn：0.75%~0.82%,P：≤0.018%,S：≤0.015%,Cr：0.25%~0.30%,V：0.020%~0.030%,Nb：0.010%~0.015%,Al：≤0.030%,Ti：≤0.0015%,Ni：≤0.10%,Cu：≤0.20%,O：≤0.0040%,N：≤0.0050%,H：≤0.00015%,% by weight of the balance of Fe and unavoidable impurities.
3. The wire rod for prestressed steel according to claim 1, wherein the specific components of said wire rod for prestressed steel are ：C：0.81%~0.85%,Si：0.20%~0.30%,Mn：0.75%~0.82%,P：≤0.018%,S：≤0.015%,Cr：0.25%~0.30%,V：0.040%~0.050%,Ni：≤0.10%,Cu：≤0.20%,O：≤0.0040%,N：≤0.0050%,H：≤0.00015%,% by weight of the balance of Fe and unavoidable impurities.
4. The wire rod for the prestressed steel, according to claim 1, is characterized in that the diameter of the wire rod for the prestressed steel is 15mm in large specification, the mechanical property of the wire rod for the prestressed steel is that the tensile strength is more than or equal to 1200MPa, the area reduction rate after aging is more than or equal to 30%, nonmetallic inclusions are A class, B class or less than or equal to 1.5 class, C class and D class or less than or equal to 1.0 class, DS class or less than or equal to 1.0 class, the sorbite rate of the wire rod reaches 85% -90%, the level of network cementite is or less than or equal to 2 class, the central carbon segregation is or less than or equal to 2 class, the decarburized layer of the wire rod is not more than 1.0D, and the wire rod for the prestressed steel is used for preparing large-specification high-strength high-speed rail plate prestressed wires and 1960-2000 MPa high-performance prestressed wires and steel strands.
5. A preparation method of a wire rod for prestressed steel, as claimed in any one of claims 1-4, is characterized by comprising the process flows of molten iron pretreatment, converter smelting, LF refining, RH refining, billet continuous casting, casting blank slow cooling pit slow cooling, casting blank heating, high-pressure water descaling, controlled rolling and controlled cooling and PF line heat preservation channel slow cooling.
6. The preparation method of the vacuum argon blowing device is characterized in that white slag retention time in the LF refining process is not less than 15min, soft blowing time is not less than 15min, the off-site temperature of an LF furnace is 1500-1535 ℃, vacuum degree in the RH refining process is not more than 67Pa, treatment time is not less than 15min, and soft blowing argon after vacuum breaking is not less than 15min.
7. The preparation method of the square billet continuous casting process according to claim 5 is characterized in that the whole process protection casting process is adopted, an integral nozzle is adopted from a tundish to a crystallizer, the liquid level of the tundish is more than or equal to 700mm, the fluctuation of the liquid level of the crystallizer is +/-3 mm, the temperature of molten steel of the tundish is more than or equal to 1479 ℃, the superheat degree is controlled to be 25-35 ℃ when casting is started, the superheat degree is 15-30 ℃ when casting is carried out continuously, the square billet size is 160mm multiplied by 12mm, the pulling speed range is 1.6-2.0 m/min, the constant pulling speed is 1.8-1.9 m/min, and the square billet is cooled by a cooling bed and then slowly cooled by a heat preservation pit for more than 72 hours.
8. The preparation method of the casting blank according to claim 5, wherein the casting blank is heated by a step heating furnace, the preheating section is 860-900 ℃, the heating section is 1080-1150 ℃, the soaking section is 1090-1150 ℃, the air-fuel ratio is 0.50-0.60, and the heating time is 1.5-2.5 h.
9. The preparation method of the casting blank according to claim 5, wherein the controlled rolling and cooling process comprises the steps of performing rough rolling unit, middle rolling unit, pre-finishing rolling unit, 3 groups of water cooling boxes for rolling by a reducing sizing unit, 2 groups of water cooling boxes for rolling by a reducing sizing unit, performing spinning and looping by a pinch roll and a spinning machine, performing controlled cooling on the casting blank by a Steyr air cooling conveying line, and collecting and conveying the casting blank by a vertical coil core collecting frame; the method comprises the steps of controlling the initial rolling temperature of rolling to 980-1050 ℃, feeding a reducing sizing mill to 880-920 ℃, spinning to 820-880 ℃, controlling the cooling process to be a water cooling process of a water cooling box after the reducing sizing mill, rapidly cooling and slow cooling a large-air-volume fan of an air cooling conveying line, wherein the speed of a No. 1 roller way in the conveying line is 0.9-1.1 m/s, the speed of other sections of the conveying line is increased by 2-5%, the air volume of a No. 1-6 variable-frequency fan is 20.0-20.5 ten thousand m 3 /h before phase change on the air cooling conveying line after spinning, the air volume of a No. 7-18 variable-frequency fan is 18.0-18.5 ten thousand m 3 /h during phase change and after phase change, and the optimal cooling process of the fan is 30%, wherein a heat preservation channel is arranged outside a PF line to ensure the temperature of the heat preservation channel, and the adoption of a vertical winding core frame for winding and transportation is beneficial to ensure large-specification wire coiling for steel.
10. The use of a wire rod for prestressed steel according to any one of claims 1 to 4, wherein said wire rod is applied to a large-sized high-strength high-speed railway slab prestressed wire or 1960 to 2000 mpa-grade high-performance prestressed wire or stranded wire.

Description

15Mm large-specification 2000 MPa-level prestressed steel wire rod and preparation method thereof Technical Field The invention belongs to the technical field of metal material preparation and metal pressure processing, and particularly relates to a 15mm large-specification 2000 MPa-level prestressed steel wire rod and a preparation method thereof. Background The prestressed steel wires and the steel strands are key materials in modern prestressed concrete structures, and along with the development of engineering construction towards longer, higher and stronger directions, higher requirements are put on the strength, durability and economy of the prestressed materials. The comprehensive properties of higher strength, larger specification and better performance become a development trend. At present, most of the wire rods for the prestressed steel wires and the steel strands in the mainstream market have diameters below 13mm, and the strength level of the prestressed material is below 1860 MPa. The use of the prestress steel with higher strength level can effectively reduce the steel consumption and the cost, and the use of the steel wires and the steel strands with larger specification can reduce the number of single-strand steel strands, simplify the anchoring system, improve the tensioning construction efficiency and be beneficial to optimizing the structural design. A15 mm large-size high-performance prestressed steel wire rod is required for a large-size high-strength high-speed rail plate prestressed steel wire, 1960-2000 MPa high-performance prestressed steel wire and steel strands, and the tensile strength of the wire rod is required to be more than or equal to 1200MPa, and the reduction of area (after aging) is required to be more than or equal to 30%. When trying to expand the wire rod gauge to 15mm and to increase its strength to 1200MPa level, the following serious technical challenges are faced: (1) The contradiction between the strength and the toughness, the high strength is easy to cause the reduction of the plasticity and the toughness. (2) And the control of the tissue uniformity is that as the specification is increased, the cooling difference between the core part and the surface part of the section of the wire rod is increased, the cooling speed of the core part of the wire rod is obviously reduced, and the defects of tissue, uneven performance, insufficient sorbitation of the core part and precipitation of abnormal martensite or carbide network tissues are easily caused. (3) The relaxation performance challenge is that the relaxation performance of prestressed steels is directly related to the long-term safety and durability of the structure, the higher the strength, the more difficult it is to control its relaxation rate at the same stress level. If the composition design of the wire rod is unreasonable or the structure is uneven, the stress relaxation rate of the finished steel strand exceeds the standard, and the long-term service requirement cannot be met. (4) The purity control requirements are strict, and the segregation of elements such as manganese, carbon and the like and the quantity and morphology control of nonmetallic inclusions are key to influencing the drawing performance of the wire rod and the fatigue life of the final steel wire. (5) Surface quality and decarburization control, namely long heating time of large-size wire rods, and more important surface decarburization control. (6) Large-sized prestressed materials (wire rods and products thereof) are prone to delayed fracture problems. (7) Cost and efficiency how to realize efficient, low-cost and stable production is an industrial bottleneck. Expanding the specification of the wire rod to 15mm and improving the strength to 1200MPa, analyzing in the prior art: (1) The composition design and the mechanical property of the traditional 15 mm-specification wire rod have the limitation that the large-specification wire rod prepared based on the traditional composition and the production process has a series of performance defects, the C-Mn-Si-Cr system is commonly adopted in the industry at present, the tensile strength can only reach more than 1150MPa, and the severe requirement of the modern important engineering high-performance prestressed material on the wire rod performance can not be met. (2) The conventional rolling and cooling control is not good for 15mm large-size high-strength prestressed steel hot rolled wire rods, and many existing production processes cannot effectively solve the problem of low sorbite rate of the large-size prestressed steel wire rods. The traditional high-speed wire rod production line air-cooled conveying line fan is small in air quantity and low in cooling capacity, when the diameter of a wire rod is increased to phi 15mm, the cooling speed of the core is reduced, the cooling capacity is insufficient to inhibit precipitation of proeutectoid ferrite and network cementite in the core, abn