Production process method of master batch wire rod for 2100 MPa bridge cable galvanized steel wire

Abstract

The invention discloses a production process method of a master batch wire rod for a 2100MPa bridge cable galvanized steel wire, which is applied to the technical field of steel manufacturing and metal products and comprises the steps of steel making, continuous casting, blooming cogging, billet continuous rolling, high-speed wire rolling, off-line salt bath isothermal heat treatment, deep processing and the like. The continuous casting adopts three-machine three-flow 400mm * 500mm bloom continuous casting, the blooming blooming rolling is performed to form 150 square billets, the high-speed rolling is performed according to a bloom segregation information optimization process, and the off-line salt bath isothermal heat treatment is performed according to a bloom continuous casting segregation state optimization process, and the hot-rolled wire rod for the 2100MPa bridge cable galvanized steel wire produced by the method has the advantages that the tensile strength reaches 1650MPa or above, the area reduction is greater than 30%, and the production cost is low. According to the master batch wire rod for the bridge cable galvanized steel wire, the steel wire strength reaches 2150 MPa or above and the torsion index reaches 20 times or above after drawing and galvanizing by a client, and the master batch wire rod can meet the performance requirements of the master batch wire rod for the bridge cable galvanized steel wire with the diameter of 5 mm and 7 mm and the pressure of 2100 MPa.

Description

Technical Field

[0001] The invention belongs to the technical field of steel manufacturing and metal products, and particularly relates to a production process method of a masterbatch wire rod for 2100MPa bridge cable galvanized steel wire. Background Art

[0002] With the development of my country's national economy, the construction of cross-sea and cross-river bridges brought about by the new infrastructure continues to emerge, and the length of the main span has exceeded 2360m. The strength of the galvanized steel wire of the bridge has reached more than 2100Mpa. While a series of bridge projects such as Zhang Jinggao Bridge, Yanji Bridge, Shiziyang Bridge, and Chaoma Bridge continue to emerge, the core cable material is urgently needed to continuously refresh records, and the requirements for manufacturing technology are getting higher and higher. New designs such as large spans, ultra-high strength, and durability require new steel materials. The wire rod for galvanized steel wire of bridge cables not only needs strength and toughness, but also requires very high uniformity of organizational properties to ensure the torsion index, relaxation performance, fatigue performance and other indicators after deep processing and galvanizing of the wire rod.

[0003] In order to obtain better organizational properties, the optimization of wire rod production process has always been the focus of research by steel mills and deep processing enterprises. Ultra-high-strength bridge cable steel wire has always been controlled by the masterbatch development of steel enterprises. Ultra-high strength requires a carbon content of more than 0.9% in the composition design, which is a hypereutectoid composition. The addition of alloy components such as Mn, Cr, and Si puts forward very strict requirements for steelmaking, continuous casting, and rolling. The emergence of salt bath heat treatment in China has provided a foundation for the research and development of ultra-high-strength cable steel wire. As early as the beginning of this century, Shougang began to set up a project to study the optimization of the organizational performance of bridge cables at the level of 87 and 92 with salt bath heat treatment technology, successfully implemented the process ideas, and conducted a lot of research on the cooling characteristics of molten salt components with different compositions in the range of 200-600℃, realizing the theoretical basis for ultra-high-strength organizational control and component design. At the same time, many steel companies adopted the design idea of ​​air cooling process + V to realize the production of steel wire masterbatch at the strength level of 1860MPa. Deep processing companies have successively opened the tension control and galvanizing process of double tension wheels to realize the control of torsion indicators. However, the research and development of galvanized steel wire for bridge cables exceeding 2000MPa has been slow. The construction of Humen Second Bridge, Yangsigang Bridge and Hutong Bridge used 1960 and 2000Mpa cable steel wires for the first time. The production of their masterbatch adopted the idea of ​​salt bath heat treatment process, which to a certain extent promoted the advancement of bridge cables to higher-level fields.

[0004] The existing 2100MPa masterbatch wire rod production process for bridge cable galvanized steel wire has the following disadvantages when used: 1. The materials with a strength of more than 2000MPa required for bridge construction have always been difficult to guarantee in terms of quality and quantity. For a period of time, the industry's research and development turned to materials such as carbon fiber, but due to cost and manufacturing process limitations, it is difficult to promote them in large quantities in the industry. 2. In the production process of bridge cable steel wire above 2000MPa, there have always been problems such as low tensile strength of wire rod, excessive mesh carbon, excessive martensite, large performance fluctuations, high wire breakage rate, substandard wire strength, and qualified rate of torsion indicators. As a result, the design of many bridge projects is slow. The most critical problem is that after exceeding 2000MPa, the material requirements of steel wire become more and more stringent. Summary of the invention

[0005] The purpose of the present invention is to target the existing 2100MPa bridge cable galvanized steel wire master batch wire rod production process method, which has the advantage of proposing a 2100MPa bridge cable galvanized steel wire wire production process method based on a full study of material requirements, which is suitable for steel mills and deep processing enterprises to develop high-end wire varieties, and integrates various process innovation technologies of steelmaking, continuous casting, steel rolling, heat treatment, and deep processing to achieve high material uniformity, high strength, high toughness, high pass rate and low cost. The 2100MPa bridge cable galvanized steel wire hot-rolled wire rod produced by the method has a tensile strength of more than 1650MPa, a surface reduction rate of more than 30%, a troostite rate of 95%, a mesh carbon of less than 0.5 grade, and a core martensite of less than 0.5 grade. After customer drawing and galvanizing, the steel wire strength reaches more than 2150MPa, and the torsion index is more than 20 times, which can meet the performance requirements of 5mm and 7mm 2100MPa bridge cable galvanized steel wire master batch wire.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: A production process of a masterbatch wire rod for 2100MPa bridge cable galvanized steel wire, comprising the following steps: S1: Steelmaking and continuous casting initial rolling S1.1) Steelmaking adopts 120t converter → LF → RH refining process; S1.2) Continuous casting uses three machines and three strands to continuously cast 400mm×500mm large square billets, which are then initially rolled into 150 square billets; S2: Billet rolling and subsequent processing S2.1) High-speed wire rolling optimizes the process based on the segregation information of large square billets; S2.2) Off-line salt bath isothermal heat treatment optimizes the process according to the segregation state of large square billet continuous casting; S2.3) Further processing, including pickling, descaling, drawing and galvanizing.

[0007] The present invention is further configured as follows: the continuous casting adopts three-machine three-stream 400mm×500mm large square billet continuous casting; the tundish is 35-40t and Mg-C refractory bricks are used; the tundish is inductively heated and the superheat is controlled within 20-30°C; the continuous casting radius is 10m, the crystallizer electromagnetic stirring and the end electromagnetic stirring are used, and soft pressure is used, and the segregation index is controlled within 1.05-1.1.

[0008] The present invention is further configured as follows: the ingot is slowly cooled after rolling, and the uniform temperature is controlled within 20-24 hours; and each ingot is coded to achieve process information traceability.

[0009] The present invention is further configured as follows: the initial rolling of the open billet is rolled into a 150 square billet, the initial rolling temperature is controlled at 1000-1100°C, continuous rolling is adopted, slow cooling is performed after rolling, shot blasting, ultrasonic flaw detection, magnetic particle flaw detection, grinding wheel grinding are performed, and the corners are ground for no less than 5 times to reduce surface defects.

[0010] The present invention is further configured as follows: the high-speed wire rolling rolling process is optimized according to the segregation information of the large square billet, the heating temperature of the segregation greater than 1.08 is controlled at 1000-1050°C, and the heating time is controlled at 1.5-2h; 6 rough rolling passes, 6 intermediate rolling passes, 8 pre-finishing rolling passes, 8 finishing rolling passes, and 4 sizing rolling passes; the wire laying temperature is controlled at 880-920°C, and after rolling, the Stelmor controlled cooling process is adopted, the cooling rate is controlled at 8-12°C / s, the phase change point is controlled at 540-580°C, and 500-520°C enters the insulation cover for slow cooling, and the slow cooling time is 30-40s; surface image flaw detection is performed during the rolling process, and a high-resolution light source is used for online detection of surface defects.

[0011] The present invention is further configured as follows: a performance test is performed after rolling, the tensile strength is controlled at 1500-1540 MPa, and the surface reduction rate is 25-30%; wire packaging and corner protection are used for packaging after rolling, and the packaging pressing force is controlled at 100-150 KN to eliminate surface defects in the packaging process.

[0012] The present invention is further configured as follows: after the high-speed wire is rolled, an offline salt bath isothermal treatment is adopted, and 16 sets of wire racks and take-up are adopted in the whole line; the salt bath process is optimized according to the segregation state of the large square billet continuous casting, the salt bath heating temperature with a segregation greater than 1.08 is 950-1000°C, arranged on 4-10 wire racks for pay-off and take-up, and the heating time is controlled at 4-5min; the salt bath adopts a 4-stage cooling, the first stage salt bath quenching cooling rate is 15-20°C / s, the second stage air cooling cooling rate is 1-3°C / s, the third stage isothermal treatment insulation is 40-60s; the fourth stage adopts slow cooling with a cooling rate of 3-5°C / s; the salt bath is cooled by a 4-stage cooling method, and the cooling rate is 15-20°C / s, and the cooling rate is 15-20°C / s. After the bath, a cleaning process is adopted to eliminate residual salt on the surface; the salt bath quenching medium adopts online impurity removal, and the impurity content is controlled at 5-10kg / t; the wire winding control coil shape and coil diameter are controlled at 1.2-1.35m; within 1 hour after the wire production, the performance data is tested by direct drawing without artificial aging, and the tensile strength is controlled at 1650-1680MPa, the area reduction rate is controlled at 30-35%, the troostite is 95-97%, the mesh carbon is 0-0.5 level, the core martensite is 0-0.5 level, and the spheroidal carbon is 0-1 level; the packaging is carried out by steel belt packaging with a compression force of 200-300KN.

[0013] The present invention is further configured as follows: the wire is further processed 3-5 days after the salt bath treatment; the deep processing adopts pickling to remove scale, and the pickling time is controlled at 15-20min; 9-11 drawing passes are adopted, and the temperature of the steel wire is controlled at 80-100°C during the drawing process; the steel wire surface is galvanized, galvanized aluminum, and galvanized aluminum-magnesium, and the galvanizing temperature is controlled at 380-420°C.

[0014] The present invention is further configured as follows: the tensile strength of the galvanized steel wire is controlled at 2150-2180 MPa, the elongation is 5-7%, and the torsion index is 15-25 times In summary, the present invention has the following beneficial effects: The present invention proposes a wire production process method for 2100MPa galvanized steel wire for bridge cables based on a thorough study of material requirements. The method is suitable for steel mills and deep processing enterprises to develop high-end wire varieties. It integrates innovative technologies in various processes of steelmaking, continuous casting, steel rolling, heat treatment, and deep processing to achieve high material uniformity, high strength, high toughness, high qualified rate, and low cost. The hot-rolled wire rod for 2100MPa galvanized steel wire for bridge cables produced by the method has a tensile strength of more than 1650MPa, a surface reduction rate of more than 30%, a troostite rate of 95%, a mesh carbon of less than 0.5 grade, and a core martensite of less than 0.5 grade. After drawing and galvanizing by customers, the steel wire strength reaches more than 2150MPa, and the torsion index is more than 20 times, which can meet the performance requirements of 5mm and 7mm 2100MPa masterbatch wire for bridge cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of electron microscope structure of hot-rolled wire rod for galvanized steel wire for beam cables of the present invention; Figure 2 It is a schematic diagram of the relationship between the interlayer spacing of the galvanized steel wire sheets of the bridge cable and the salt bath process of the present invention; Figure 3 This is a schematic diagram of the electron microscope structure of the galvanized steel wire for bridge cables of the present invention; Figure 4 The present invention is a schematic flow chart of a process for producing a master batch wire rod for galvanized steel wire for bridge cables. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings. Example

[0017] This method is applied in the high-speed production of 5mm, 2100MPa galvanized steel wire for bridge cables, using 13.5mm92Si wire rod, with a tensile strength of more than 1650MPa, a surface reduction rate of 33%, a troostite of 95%, a reticular carbon level of less than 0.5, a spheroidal carbon level of less than 0.5, and a martensite level of zero.

[0018] The steelmaking process uses all molten iron, the molten iron pretreatment adopts KR desulfurization process, using CaO-Ca desulfurizer, the converter adopts 120t production process, the refining LF cycle is 60min, the vacuum treatment adopts RH process, the cycle is 40min, the vacuum is maintained for 15min, and the soft blowing is 15minmin.

[0019] The KR process is used for molten iron pretreatment, which reduces the S element in molten iron at a low cost; the refining process fully ensures the removal of harmful elements S and P and inclusions; vacuum treatment controls the oxygen content in molten steel and improves the purity of molten steel; the control of impurity elements is shown in Table 2.

[0020] Table 2. Impurity element control of 2100MPa bridge cable galvanized steel wire The continuous casting adopts three-machine three-stream 400mm×500mm large square billet continuous casting; the tundish is 35t and made of Mg-C refractory bricks; the tundish is induction heated and the superheat is controlled within 20℃; the continuous casting radius is 10m, and the crystallizer and end electromagnetic stirring are adopted, and light pressure is adopted, and the segregation index is controlled at 1.05; the billet is slowly cooled after rolling, and the uniform temperature is controlled at 20 hours; each billet is sprayed with code to realize process information traceability.

[0021] The process of large square billet is the key to the production of ultra-high strength cable steel wire. On the one hand, it ensures the compression ratio, and on the other hand, it realizes the homogenization of the material. The large reduction leads to the refinement of grains, the diffusion of segregation elements, and the rolling and welding of loose core. The three-machine three-stream and the tonnage of the tundish realize the bending of the tundish during long-term casting, which affects the center position of the continuous casting nozzle and realizes the stable control of the quality of the billet in mass production. The tundish adopts induction heating to achieve low superheat steel casting, which plays a key role in reducing continuous casting segregation. Table 3 shows the continuous casting segregation index under different superheat.

[0022] Table 3. Segregation index at different superheat The initial rolling process is to roll the blank into 150 square billet; the initial rolling temperature is controlled at 1000℃ and continuous rolling is adopted; after rolling, the billet is slowly cooled, shot blasting, ultrasonic flaw detection, magnetic particle flaw detection, and grinding wheel are performed, and the corners are ground for no less than 5 times to reduce surface defects.

[0023] The initial rolling heating temperature is controlled at 1000-1100℃, and the segregation is reduced by extending the heating time. Table 4 shows the changes in the segregation index of the billet under different heating processes.

[0024] Table 4. Changes in segregation index of billet under different heating processes The high-speed wire rolling process is optimized according to the segregation information of the large square billet, the heating temperature is controlled at 1000℃, and the heating time is controlled at 1.5h; there are 6 rough rolling passes, 6 intermediate rolling passes, 8 pre-finishing rolling passes, 8 finishing rolling passes, and 4 sizing rolling passes; the wire drawing temperature is controlled at 880℃, and the Stelmor controlled cooling process is adopted after rolling. The cooling rate is controlled at 8℃ / s, the phase change point is controlled at 540℃, and it enters the insulation cover at 500℃ for slow cooling, and the slow cooling time is 30s; surface imaging flaw detection is carried out during the rolling process, and a high-resolution light source is used for online detection of surface defects; performance testing is carried out after rolling, the tensile strength is controlled at 1500MPa, and the surface reduction rate is 25%; wire packaging and corner protection are used for packaging after rolling, and the packaging pressing force is controlled at 100KN to eliminate surface defects in the packaging process.

[0025] The high-speed wire rolling process is adjusted according to the index of continuous casting segregation, as shown in Table 4. The heating process is automatically generated by scanning the ingot coding information in front of the heating furnace.

[0026] Table 4 Changes of segregation index after secondary slab rolling under different heating processes The grain size is controlled by rolling, and the finishing rolling temperature is controlled at 870-910℃. The grain sizes at different finishing rolling temperatures and spinning temperatures are shown in Table 5. The grain size directly represents the degree of refinement of the rolling organization. The finer the grain, the better the material strength and toughness. The grain size is hereditary in the later heat treatment process and needs to be focused on control; Table 4 Grain size under different rolling processes Cooling after spinning plays a great role in controlling the mesh carbon of the material organization. The mesh carbon has a great influence on the elimination of the later heat treatment process. Mesh carbon greater than level 4 will be hereditary. The cooling rate after rolling plays a key role in the improvement of mesh carbon, which is reflected in the comprehensive performance of the material as shown in Table 5.

[0027] Table 5. Changes in microstructure and properties under different Stelmor air cooling rates After high-speed wire rolling, offline salt bath isothermal treatment is adopted. The whole line adopts 16 sets of wire racks and take-up. The salt bath process is optimized according to the segregation state of large square billet continuous casting. The salt bath heating temperature is 950℃, arranged on 4-10 wire racks for pay-off and take-up, and the heating time is controlled at 4min. The salt bath adopts 4-stage cooling, the first stage of salt bath quenching cooling rate is 15℃ / s, the second stage of air cooling cooling rate is 1℃ / s, and the third stage of isothermal treatment is kept warm for 40s; the fourth stage adopts slow cooling with a cooling rate of 3℃ / s; after the salt bath, Cleaning process to eliminate residual salt on the surface; salt bath quenching medium adopts online impurity removal, and the impurity content is controlled at 5kg / t; the coil shape and coil diameter are controlled at 1.2m; within 1 hour after the wire is produced, the performance data is tested by direct drawing without artificial aging, the tensile strength is controlled at 1650MPa, the area reduction rate is controlled at 30%, the troostite is 95%, the mesh carbon is grade 0, the core martensite is grade 0, and the spheroidal carbon is grade 0-1; the packaging is carried out by steel belt packaging with a compression force of 200KN.

[0028] Offline salt bath treatment is the key to the entire process. By adjusting the production process and organizational method, the mechanical properties of the ultra-high-strength cable wire masterbatch are optimized. At the same time, the incoming materials are managed in an informationized manner through the segregation of incoming materials and the level of carbon mesh. The heating process and rack number are adjusted to achieve stable control of organizational performance. The heating medium of the heating furnace uses natural gas, with an hourly demand of 120-150m³. The open flame heating method is used to achieve rapid heating of the wire rod. At the same time, the residual sun content is adjusted between 4-6%, and the surface decarburization layer of the wire is removed in the heating furnace to achieve zero surface decarburization. The salt bath process adopts a four-stage process. The first stage realizes rapid cooling of the wire rod to ensure the refinement of the carbon network and troostite rate and the interlamellar spacing; the second stage of air cooling realizes the connection between the first stage of rapid cooling and the third stage of isothermal cooling; the temperature of the third stage of isothermal cooling is 5-10℃ higher than the temperature of the first stage to ensure sufficient troostitization of the structure; the third stage of slow cooling ensures that the residual austenite undergoes sufficient eutectoid transformation, reduces the martensite content, and realizes the material is free of aging.

[0029] Table 6. Changes in organizational properties under different salt bath processes The wire is further processed 3 days after salt bath treatment; the deep processing adopts pickling to remove scale, and the pickling time is controlled at 15min; 9 drawing passes are adopted, and the temperature of the steel wire is controlled at 80℃ during the drawing process; the steel wire surface is galvanized, galvanized aluminum, and galvanized aluminum-magnesium, and the galvanizing temperature is controlled at 380℃; the tensile strength of the steel wire after galvanizing is controlled at 2150MPa, the elongation is 5%, and the torsion index is 15 times.

[0030] The final performance of the steel wire focuses on tensile strength and torsion index. The control of the performance of the masterbatch production organization in the early stage lays a good foundation for the final deep processing. The performance of the finished steel wire under different masterbatch tensile strengths is shown in Table 7.

[0031] Table 7. Finished steel wire properties under masterbatch tensile strength Example

[0032] This method is applied in the high-speed production of 7mm, 2100MPa galvanized steel wire for bridge cables, using 14mm92Si wire rod, with a tensile strength of more than 1680MPa, a surface reduction rate of 30%, a troostite of 97%, a reticular carbon of less than 0.5 grade, a spheroidal carbon of less than 0.5 grade, and a martensite of zero grade.

[0033] The steelmaking process uses all molten iron, the molten iron pretreatment adopts KR desulfurization process, using CaO-Ca desulfurizer, the converter adopts 120t production process, the refining LF cycle is 80min, the vacuum treatment adopts RH process, the cycle is 50min, the vacuum is maintained for 20min, and the soft blowing is 20min.

[0034] The continuous casting adopts three-machine three-stream continuous casting of 400mm×500mm large square billets; the tundish is 40t and made of Mg-C refractory bricks; the tundish is induction heated and the superheat is controlled at 30℃; the continuous casting radius is 10m, and the crystallizer and end electromagnetic stirring are adopted, and light pressure is adopted, and the segregation index is controlled at 1.1; the billet is slowly cooled after rolling, and the uniform temperature is controlled at 24 hours; each billet is sprayed with code to realize process information traceability.

[0035] The initial rolling process is to roll the open billet into 150 square billet; the initial rolling temperature is controlled at 1100℃, and continuous rolling is adopted; after rolling, the billet is slowly cooled, and shot blasting, ultrasonic flaw detection, magnetic particle flaw detection, and grinding wheel grinding are performed. The corners are ground for no less than 5 times to reduce surface defects.

[0036] The high-speed wire rolling process is optimized according to the segregation information of large square billets. The heating temperature for segregation greater than 1.08 is controlled at 1050℃, and the heating time is controlled at 2h; 6 rough rolling passes, 6 intermediate rolling passes, 8 pre-finishing rolling passes, 8 finishing rolling passes, and 4 sizing rolling passes; the wire drawing temperature is controlled at 920℃, and the Stelmor controlled cooling process is adopted after rolling. The cooling rate is controlled at 12℃ / s, the phase change point is controlled at 580℃, and the steel enters the insulation cover at 520℃ for slow cooling, and the slow cooling time is 40s; surface imaging flaw detection is carried out during the rolling process, and a high-resolution light source is used for online detection of surface defects; performance testing is carried out after rolling, and the tensile strength is controlled at 1540MPa, and the surface reduction rate is 30%; wire packaging and corner protection are used for packaging after rolling, and the packaging pressing force is controlled at 150KN to eliminate surface defects in the packaging process.

[0037] After high-speed wire rolling, offline salt bath isothermal treatment is adopted. The whole line adopts 16 sets of wire racks and take-up. The salt bath process is optimized according to the segregation state of large square billet continuous casting. The salt bath heating temperature is 1000℃ for segregation greater than 1.08. It is arranged on 4-10 wire racks for pay-off and take-up, and the heating time is controlled at 5min. The salt bath adopts 4-stage cooling. The first stage is salt bath quenching cooling rate is 20℃ / s, the second stage is air cooling cooling rate is 3℃ / s, and the third stage isothermal treatment is kept warm for 60s. The fourth stage adopts slow cooling with a cooling rate of 5℃ / s. After the bath, a cleaning process is used to eliminate residual salt on the surface; the salt bath quenching medium adopts online impurity removal, and the impurity content is controlled at 10kg / t; the wire winding control coil shape and coil diameter are controlled at 1.35m; within 1 hour after the wire production, the performance data is tested by direct drawing without artificial aging, and the tensile strength is controlled at 1680MPa, the area reduction rate is controlled at 35%, the troostite is 97%, the mesh carbon is 0.5 level, the core martensite is 0 level, and the spheroidal carbon is 1 level; the packaging is carried out by steel belt packaging with a compression force of 300KN.

[0038] The wire is further processed 5 days after salt bath treatment; the deep processing adopts pickling to remove scale, and the pickling time is controlled at 20min; 11 drawing passes are adopted, and the temperature of the steel wire is controlled at 100℃ during the drawing process; the steel wire surface is galvanized, galvanized aluminum, and galvanized aluminum-magnesium, and the galvanizing temperature is controlled at 420℃; the tensile strength of the steel wire after galvanizing is controlled at 2180MPa, the elongation is 7%, and the torsion index is 25 times. Implementation Effect

[0039] Through the present invention, the demand of the Bridge Bureau for galvanized steel wire for bridges has been met, and 5mm and 7mm cable galvanized steel wire with a strength of more than 2100MPa has been successfully developed, with a yield rate of more than 95%, an annual output of more than 50,000 tons, annual sales of 300 million, and annual economic benefits of more than 40 million. It saves more than 30% of steel consumption for bridge construction, shortens the construction period by 1 year, and increases the service life from the current 50 years to 100 years, helping the construction of major projects such as cross-sea and cross-river bridges in my country and forming an international brand for China's high-end construction.

[0040] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A production process for a masterbatch wire rod for 2100MPa bridge cable galvanized steel wire, comprising the following steps: S1: Steelmaking and continuous casting initial rolling S1.1) Steelmaking adopts 120t converter → LF → RH refining process; S1.2) Continuous casting uses three machines and three strands to continuously cast 400mm×500mm large square billets, which are then initially rolled into 150 square billets; S2: Billet rolling and subsequent processing S2.1) High-speed wire rolling optimizes the process based on the segregation information of large square billets; S2.2) Off-line salt bath isothermal heat treatment optimizes the process according to the segregation state of large square billet continuous casting; S2.3) Further processing, including pickling, descaling, drawing and galvanizing.

2. The method for producing a masterbatch wire rod for 2100MPa galvanized steel wire for bridge cables according to claim 1, characterized in that: The steelmaking process uses all molten iron, the molten iron pretreatment adopts the KR desulfurization process, uses CaO-Ca desulfurizer, the converter adopts 120t production process, the refining LF cycle is 60-80min, the vacuum treatment adopts the RH process, the cycle is 40-50min, the vacuum is maintained for 15-20min, and the soft blowing is 15min-20min.

3. The method for producing a masterbatch wire rod for 2100MPa galvanized steel wire for bridge cables according to claim 1, characterized in that: The continuous casting adopts three-machine three-stream continuous casting of 400mm×500mm large square billets; the tundish is 35-40t and made of Mg-C refractory bricks; the tundish is induction heated and the superheat is controlled within 20-30°C; the continuous casting radius is 10m, the crystallizer electromagnetic stirring and the end electromagnetic stirring are adopted, and soft pressure is adopted, and the segregation index is controlled within 1.05-1.

1.

4. The method for producing a masterbatch wire rod for 2100MPa galvanized steel wire for bridge cables according to claim 3, characterized in that: The ingot is slowly cooled after rolling, and the uniform temperature is controlled within 20-24 hours; each ingot is sprayed with code to realize process information traceability.

5. The method for producing a master batch wire rod for 2100MPa galvanized steel wire for bridge cables according to claim 1, characterized in that: The initial rolling process is to roll the billet into a 150 square billet, control the initial rolling temperature at 1000-1100°C, adopt continuous rolling, slow cooling after rolling, and perform shot blasting, ultrasonic flaw detection, magnetic particle flaw detection, and grinding wheel grinding. The corners are ground for no less than 5 times to reduce surface defects.

6. The method for producing a master batch wire rod for 2100MPa galvanized steel wire for bridge cables according to claim 1, characterized in that: The high-speed wire rolling process is optimized according to the segregation information of the large square billet, and the heating temperature for the segregation greater than 1.08 is controlled at 1000-1050°C, and the heating time is controlled at 1.5-2h; 6 rough rolling passes, 6 intermediate rolling passes, 8 pre-finishing rolling passes, 8 finishing rolling passes, and 4 sizing rolling passes; the wire laying temperature is controlled at 880-920°C, and after rolling, the Stelmor controlled cooling process is adopted, the cooling rate is controlled at 8-12°C / s, the phase change point is controlled at 540-580°C, and the steel enters the heat preservation cover at 500-520°C for slow cooling, and the slow cooling time is 30-40s; surface image flaw detection is performed during the rolling process, and a high-resolution light source is used for online detection of surface defects.

7. The method for producing a master batch wire rod for 2100MPa galvanized steel wire for bridge cables according to claim 6, characterized in that: After rolling, the performance test is carried out, and the tensile strength is controlled at 1500-1540MPa, and the surface reduction rate is 25-30%; after rolling, the packaging adopts wire packaging and corner protection, and the packaging compression force is controlled at 100-150KN to eliminate surface defects in the packaging process.

8. The method for producing a master batch wire rod for 2100MPa galvanized steel wire for bridge cables according to claim 1, characterized in that: After the high-speed wire is rolled, an offline salt bath isothermal treatment is adopted, and 16 sets of wire racks and take-up are adopted in the whole line; the salt bath process is optimized according to the segregation state of the large square billet continuous casting, and the salt bath heating temperature for the segregation greater than 1.08 is 950-1000°C, arranged on 4-10 wire racks for pay-off and take-up, and the heating time is controlled at 4-5min; the salt bath adopts a 4-stage cooling, the first stage salt bath quenching cooling rate is 15-20°C / s, the second stage air cooling cooling rate is 1-3°C / s, the third stage isothermal treatment insulation is 40-60s; the fourth stage adopts slow cooling, the cooling rate is 3-5°C / s; after the salt bath, a cleaning is adopted The cleaning process is used to eliminate residual salt on the surface; the salt bath quenching medium adopts online impurity removal, and the impurity content is controlled at 5-10kg / t; the wire winding control coil shape and coil diameter are controlled at 1.2-1.35m; the performance data of the wire rod is tested by direct drawing without artificial aging within 1 hour after production, and the tensile strength is controlled at 1650-1680MPa, the area reduction rate is controlled at 30-35%, the troostite is 95-97%, the mesh carbon is 0-0.5 level, the core martensite is 0-0.5 level, and the spheroidal carbon is 0-1 level; the packaging adopts steel belt packaging with a compression force of 200-300KN.

9. The method for producing a master batch wire rod for 2100MPa galvanized steel wire for bridge cables according to claim 1, characterized in that: The wire is further processed 3-5 days after the salt bath treatment; the deep processing adopts pickling to remove scale, and the pickling time is controlled at 15-20min; 9-11 drawing passes are adopted, and the temperature of the steel wire is controlled at 80-100°C during the drawing process; the steel wire surface is galvanized, galvanized aluminum, and galvanized aluminum-magnesium, and the galvanizing temperature is controlled at 380-420°C.

10. The method for producing a master batch wire rod for 2100MPa galvanized steel wire for bridge cables according to claim 9, characterized in that: The tensile strength of the galvanized steel wire is controlled at 2150-2180 MPa, the elongation is 5-7%, and the torsion index is 15-25 times.

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