Processing technology of high-strength smooth prestressed strand steel, steel and application

Abstract

The application relates to the technical field of steel materials, and particularly discloses a processing technology of high-strength smooth prestressed steel strand steel material, the steel material and application. The processing technology comprises the following steps: S1, continuous casting; S2, heating; S3, rolling; and S4, cooling, to obtain high-strength steel material. The molten steel mainly comprises the following chemical components in percentage by weight: C: 0.81-0.85%, Si: 0.25-0.35%, Mn: 0.72-0.82%, Cr: 0.22-0.30%, V: 0.09-0.11%, La: 0.15-0.22%, Ni <=0.1%, Cu <=0.20%, P <=0.025%, S <=0.025%, N <=0.005%, O <=0.001%, H <=0.0002%, and the balance is Fe. The steel material obtained through the processing has the advantages of high tensile strength, high sorbite rate and uniform structure, and the quality of the steel material is improved.

Description

Technical Field

[0001] This application relates to the field of steel technology, and more specifically, to a processing technology for high-strength, smooth, prestressed stranded steel, as well as the steel and its applications. Background Technology

[0002] High-strength smooth prestressed stranded wire is a steel cable made of multiple strands of steel. It has the advantages of high strength, good relaxation, and straightness when unwound, and is suitable for railways, highways, bridges, crane beams, buildings, etc. Due to the special working conditions and environment of high-strength smooth prestressed stranded wire, higher requirements are placed on its product performance. Correspondingly, the steel must have higher tensile strength and sorbite ratio, and it must also have uniform structure and stable performance.

[0003] A high-strength prestressed steel is disclosed in related technologies, which is mainly composed of the following chemical composition by weight percentage: C: 0.80-0.85%, Si: 0.15-0.30%, Mn: 0.70-0.90%, Cr: 0.15-0.30%, V: 0.02-0.05%, P≤0.025%, S≤0.025%, Ni≤0.10%, Cu≤0.05%, Mo≤0.03%, with the balance being Fe. The steel obtained by this technical solution has a tensile strength of approximately 1240 MPa and a sorbite content of approximately 95%. Further improvements in both tensile strength and sorbite content are needed. Summary of the Invention

[0004] In order to improve the tensile strength and sorbite content of steel, this application provides a processing technology, steel and application of high-strength smooth prestressed strand steel.

[0005] In a first aspect, this application provides a processing technology for high-strength, smooth, prestressed stranded steel, employing the following technical solution:

[0006] A processing method for high-strength, smooth, prestressed stranded steel includes the following steps:

[0007] S1. Continuous casting: Molten steel is poured into the tundish and then transferred to the crystallizer for primary cooling. The molten steel cools along the inner wall of the crystallizer and forms a primary product with molten steel as the liquid core and the surrounding walls as the billet. The primary product is then pulled out from the crystallizer outlet, and the liquid core in the primary product is cooled a second time to obtain the billet.

[0008] Throughout the continuous casting process, the molten steel is always protected with protective slag, and the liquid core in the initial product is always electromagnetically stirred.

[0009] Furthermore, the molten steel is mainly composed of the following chemical components by weight percentage: C: 0.81-0.85%, Si: 0.25-0.35%, Mn: 0.72-0.82%, Cr: 0.22-0.30%, V: 0.09-0.11%, La: 0.15-0.22%, Ni≤0.1%, Cu≤0.20%, P≤0.025%, S≤0.025%, N≤0.005%, O≤0.001%, H≤0.0002%, with the balance being Fe;

[0010] S2. Heating: Under blast furnace gas and a positive pressure of 15-25 Pa, the billet is heated to 590-610℃ and held for 30-50 min. Then, the temperature is raised to 890-910℃ and held for 30-50 min. After that, the temperature is raised to 1160-1180℃ and held for 30-50 min to obtain a hot billet.

[0011] S3. Rolling: The hot billet is rolled at an initial rolling temperature of 980-1000℃, a finishing rolling temperature of 910-930℃, and a wire drawing temperature of 850-870℃ to obtain a semi-finished product.

[0012] S4. Cooling: The semi-finished product is cooled to 655-665℃ at a rate of 14-16℃ / s, then cooled to 450-470℃ at a rate of 1-3℃ / s, then heated to 635-645℃, then cooled to 290-310℃ at a rate of 14-16℃ / s, and finally cooled to room temperature to obtain steel.

[0013] The steel obtained by adopting the above technical solution has a tensile strength >1400MPa, elongation ≥17.0%, reduction of area >42%, sorbite content ≥95%, grain size ≥9.0 grade, and center segregation grade 0. This gives the steel the advantages of high tensile strength, high plasticity, high sorbite content, small grain size, and uniform structure, thereby improving the quality of the steel and meeting higher requirements.

[0014] In this processing technology, molten steel is transferred to a crystallizer for primary cooling and indirect heat exchange, yielding a preliminary product with an internal liquid core and surrounding billet walls. A secondary cooling process then occurs, resulting in direct heat exchange and a billet. This combination of intermittent heat exchange during primary cooling and direct heat exchange during secondary cooling not only facilitates continuous casting but also significantly improves heat exchange efficiency and reduces steel processing costs. Furthermore, electromagnetic stirring throughout the continuous casting process keeps the molten steel in a state of constant agitation during solidification, reducing chemical segregation and increasing microstructure uniformity. The billet is then heated and rolled to obtain a semi-finished product. This semi-finished product is then subjected to rapid cooling, slow cooling, heating, and rapid cooling to obtain the finished steel. Heating during this process enlarges the grains in the semi-finished product, further improving the uniformity of its chemical composition. Rapid cooling effectively increases the sorbite ratio and refines the grain size, improving the steel's performance and quality.

[0015] In the chemical composition of molten steel, based on the basic chemical components C, Si, Mn, and Fe, Cr, V, and La are added simultaneously. Cr can enhance precipitation, refine the pearlite cluster size, and thus refine the grain size; V can inhibit austenite grain growth, delay pearlite transformation, refine the pearlite cluster size, and reduce lamellar spacing; La can improve grain uniformity, refine grain size, and improve hardenability. In this application, by utilizing the synergistic effect between Cr, V, and La, the tensile strength, sorbite ratio, and grain size of the steel are greatly improved, and the center segregation level of the steel is also significantly reduced, giving the steel excellent comprehensive properties.

[0016] Optionally, the molten steel is mainly composed of the following chemical composition by weight percentage: C: 0.83%, Si: 0.30%, Mn: 0.77%, Cr: 0.26%, V: 0.10%, La: 0.18%, Ni≤0.1%, Cu≤0.20%, P≤0.025%, S≤0.025%, N≤0.005%, O≤0.001%, H≤0.0002%, with the balance being Fe.

[0017] Optionally, in step S1, the frequency of the electromagnetic stirring is 8-12 Hz.

[0018] By adopting the above technical solution, the frequency of electromagnetic stirring is optimized, which facilitates the stirring of the liquid core in the initial product, increases the uniformity of the steel, and improves the quality of the steel.

[0019] In several implementations, the electromagnetic stirring frequency is 10 Hz, but it can also be set to 8 Hz, 9 Hz, 11 Hz, 12 Hz, etc., as needed.

[0020] Optionally, in step S1, the pulling speed of the initial product at the crystallizer outlet is 1.0-1.2 m / min.

[0021] If the initial drawing speed is too low, it will affect the steel processing efficiency and production capacity; if the initial drawing speed is too fast, it will increase the friction between the initial drawing and the crystallizer, which may cause bubbling and steel leakage in the initial drawing, thus affecting the performance and processing stability of the steel. When the initial drawing speed is selected between 1.0-1.2 m / min, it can ensure the steel production capacity while giving the steel good performance, quality and processing stability.

[0022] Furthermore, the primary cooling uses cooling water, which indirectly contacts the molten steel and exchanges heat indirectly; the secondary cooling also uses cooling water, which directly contacts the finished product and exchanges heat directly. The temperature of the cooling water is 10℃.

[0023] Optionally, in step S1, the thickness of the billet wall at the outlet of the crystallizer of the initial product is 19.52-21.34 mm, and the liquid core depth is 12.31-14.90 mm.

[0024] If the thickness of the billet wall is too large and the depth of the liquid core is too small, the heat exchanged indirectly during primary cooling increases while the heat exchanged directly during secondary cooling decreases, reducing heat exchange efficiency and increasing processing costs. Conversely, if the thickness of the billet wall is too small and the depth of the liquid core is too large, bubbling and steel leakage may occur in the initial product, affecting the steel's performance and processing stability. Selecting a billet wall thickness of 19.52-21.34 mm and a liquid core depth of 12.31-14.90 mm at the crystallizer outlet for the initial product ensures good steel performance, quality, and processing stability while reducing steel processing costs.

[0025] In several implementation schemes, the initial product is pulled out of the crystallizer outlet at a speed of 1.1 m / min, but the speed can also be set to 1.0 m / min, 1.2 m / min, etc., as needed.

[0026] Optionally, the billet is a square billet with a square cross-section and a side length of 130-160 mm.

[0027] In several implementation schemes, the side length of the billet is 160mm, but it can also be set to 130mm, 140mm, 150mm, etc., as needed.

[0028] Optionally, the superheating temperature of the molten steel is 15-25℃.

[0029] If the superheating temperature of molten steel is too low, it will affect the fluidity of the steel and continuous casting; if the superheating temperature is too high, it will increase the processing cost of the steel. However, when the superheating temperature of molten steel is selected between 15-25℃, it can maintain good fluidity of the steel and also save costs.

[0030] In several implementation schemes, the superheating temperature of the molten steel is 20°C, but it can also be set to 15°C, 25°C, etc., as needed.

[0031] Furthermore, the oxygen content in the blast furnace gas should be ≤3wt% and the water content ≤10g / Nm³. 3 Preferably, the blast furnace gas has an oxygen content ≤1.5wt% and a water content ≤6g / Nm³. 3 .

[0032] Optionally, the diameter of the steel is 6.5-10mm.

[0033] By adopting the above technical solutions, steel can be processed into different diameters according to actual needs.

[0034] In several implementations, the diameter of the steel is 6.5 mm, but it can also be set to 7 mm, 8 mm, 9 mm, 10 mm, etc., as needed.

[0035] Secondly, this application provides a type of steel, which adopts the following technical solution:

[0036] A type of steel, said steel being manufactured using the processing technology described above for high-strength, smooth, prestressed stranded wire.

[0037] Thirdly, this application provides a high-strength, smooth, prestressed stranded wire, employing the following technical solution:

[0038] A high-strength, smooth, prestressed stranded wire comprises multiple steel strands twisted together, wherein the steel strands are the steel strands described above.

[0039] In summary, this application has at least the following beneficial effects:

[0040] The processing technology for high-strength, smooth prestressed strand steel disclosed in this application improves and upgrades the processing technology by synergistically enhancing continuous casting, heating, rolling, and cooling. Furthermore, it optimizes the chemical composition of the molten steel, combining the synergistic effects of C, Si, Mn, Cr, V, and La. This results in steel with tensile strength >1400MPa, elongation ≥17.0%, reduction of area >42%, sorbite content ≥95%, grain size ≥9.0 grade, and center segregation of 0 grade. This provides the steel with advantages such as high tensile strength, high plasticity, high sorbite content, small grain size, and uniform microstructure, thereby improving steel quality and meeting higher requirements. Detailed Implementation

[0041] To make this application easier to understand, the following detailed description will be provided with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of application of this application. Unless otherwise specified, the raw materials or components used in this application can be obtained commercially or by conventional methods.

[0042] Example

[0043] Example 1

[0044] A processing method for high-strength, smooth, prestressed stranded steel includes the following steps:

[0045] S1. Continuous Casting: Molten steel is poured into a tundish at a temperature of 1470℃, with a superheat temperature of 20℃. It is then transferred to a crystallizer for primary cooling, where the molten steel cools along the inner wall of the crystallizer, forming a primary product with the molten steel as the liquid core and the surrounding walls as the billet. The primary product is then pulled out of the crystallizer outlet at a speed of 1.1 m / min, with a wall thickness of 20.37 mm and a liquid core depth of 13.61 mm at the outlet. The liquid core in the primary product is then subjected to secondary cooling, solidifying to form a billet that is solid both inside and out. The billet is a square billet with a square cross-section and a side length of 160 mm.

[0046] The primary cooling process uses cooling water, which indirectly contacts the molten steel and exchanges heat indirectly. The secondary cooling process also uses cooling water, which directly contacts the finished product and exchanges heat directly. The temperature of the cooling water is 10℃.

[0047] Furthermore, throughout the continuous casting process, the molten steel is always protected with protective slag, which is 10mm thick; the liquid core in the initial product is always electromagnetically stirred at a frequency of 10Hz.

[0048] The protective slag is made from the following raw materials in weight percentages: silicon dioxide 29.4%, calcium oxide 28.8%, aluminum oxide 5.2%, ferric oxide 1.1%, magnesium oxide 2.5%, sodium oxide 13.6%, lithium oxide 2.4%, calcium fluoride 5.8%, with the balance being impurities.

[0049] Molten steel is composed of the following chemical composition by weight percentage: C: 0.83%, Si: 0.30%, Mn: 0.77%, Cr: 0.26%, V: 0.10%, La: 0.18%, Ni: 0.05%, Cu: 0.04%, P: 0.008%, S: 0.007%, N: 0.003%, O: 0.001%, H: 0.0002%, with the balance being Fe.

[0050] S2. Heating: Under blast furnace gas and a positive pressure of 20 Pa, the billet is heated to 600℃ and held for 40 minutes. Then, the temperature is increased to 900℃ and held for 40 minutes. After that, the temperature is increased to 1170℃ and held for 40 minutes to obtain a hot billet.

[0051] The blast furnace gas contains 1.5 wt% oxygen and 6 g / Nm³ of water. 3 .

[0052] S3. Rolling: The hot billet is rolled at an initial rolling temperature of 990℃, a finishing rolling temperature of 920℃, and a wire drawing temperature of 860℃ to obtain a semi-finished product.

[0053] S4. Cooling: The semi-finished product is cooled to 660℃ at a rate of 15℃ / s, then to 460℃ at a rate of 2℃ / s, then heated to 640℃, then cooled to 300℃ at a rate of 15℃ / s, and finally cooled to 25℃ to obtain steel. The diameter of the steel is 6.5mm.

[0054] Example 2

[0055] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that the chemical composition of the molten steel is different in step S1.

[0056] Molten steel is composed of the following chemical composition by weight percentage: C: 0.81%, Si: 0.35%, Mn: 0.82%, Cr: 0.22%, V: 0.11%, La: 0.15%, Ni: 0.08%, Cu: 0.02%, P: 0.011%, S: 0.006%, N: 0.003%, O: 0.001%, H: 0.0002%, with the balance being Fe.

[0057] Example 3

[0058] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that the chemical composition of the molten steel is different in step S1.

[0059] Molten steel is composed of the following chemical composition by weight percentage: C: 0.85%, Si: 0.25%, Mn: 0.72%, Cr: 0.30%, V: 0.09%, La: 0.22%, Ni: 0.06%, Cu: 0.05%, P: 0.006%, S: 0.008%, N: 0.003%, O: 0.001%, H: 0.0002%, with the balance being Fe.

[0060] Example 4

[0061] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that step S4 is different.

[0062] Step S4 specifically involves cooling the semi-finished product to 665°C at a rate of 14°C / s, then cooling it to 470°C at a rate of 3°C / s, then heating it to 645°C, then cooling it to 310°C at a rate of 14°C / s, and finally cooling it to 25°C to obtain steel. The diameter of the steel is 6.5 mm.

[0063] Example 5

[0064] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that step S4 is different.

[0065] Step S4 specifically involves cooling the semi-finished product to 655°C at a rate of 16°C / s, then cooling it to 450°C at a rate of 1°C / s, then heating it to 635°C, then cooling it to 290°C at a rate of 16°C / s, and finally cooling it to 25°C to obtain steel. The diameter of the steel is 6.5 mm.

[0066] Comparative Example

[0067] Comparative Example 1

[0068] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that, in step S1, Cr, V, and La are not added to the chemical composition of the molten steel.

[0069] Comparative Example 2

[0070] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that, in step S1, V and La are replaced with an equal amount of Cr in the chemical composition of the molten steel.

[0071] Comparative Example 3

[0072] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that, in step S1, Cr and La are replaced with equal amounts of V in the chemical composition of the molten steel.

[0073] Comparative Example 4

[0074] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that, in step S1, Cr and V are replaced by an equal amount of La in the chemical composition of the molten steel.

[0075] Comparative Example 5

[0076] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that, in step S1, La is replaced by equal amounts of Cr and V in the chemical composition of the molten steel, and the weight ratio of Cr and V is 13:5.

[0077] Comparative Example 6

[0078] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that, in step S1, V is replaced by equal amounts of Cr and La in the chemical composition of the molten steel, and the weight ratio of Cr to La is 13:9.

[0079] Comparative Example 7

[0080] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that, in step S1, Cr is replaced by equal amounts of V and La in the chemical composition of the molten steel, and the weight ratio of V to La is 5:9.

[0081] Comparative Example 8

[0082] A processing technology for high-strength bright prestressed stranded steel differs from that of Example 1 in that, in step S1, the weight percentage of V in the chemical composition of the molten steel is different, specifically V: 0.06%.

[0083] Comparative Example 9

[0084] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that, in step S1, the liquid core in the initial product is never electromagnetically stirred throughout the continuous casting process.

[0085] Comparative Example 10

[0086] A processing technology for high-strength, smooth, prestressed stranded steel differs from that of Example 1 in that step S4 is different.

[0087] Step S4 specifically involves cooling the semi-finished product to 660°C at a rate of 15°C / s, then cooling it to 460°C at a rate of 2°C / s. Afterward, it is cooled to 25°C to obtain steel. The diameter of the steel is 6.5 mm.

[0088] Performance testing

[0089] The steels obtained in Examples 1-5 and Comparative Examples 1-10 were used as samples, and the following performance tests were performed on the samples. The test results are shown in Table 1.

[0090] In accordance with GB / T228.1-2010 "Metallic materials - Tensile testing - Part 1: Test at room temperature", the tensile strength, elongation, and reduction of area of ​​the specimens were tested.

[0091] According to YB / T169-2014 "Metallographic Test Method for Sorbite Content of High Carbon Steel Wire Rod", the sorbite content of the sample was tested.

[0092] According to GB / T33165-2016 "Quantitative Analysis Method for Center Segregation of High Carbon Steel Wire Rod", the center segregation level of the sample was tested, and the lower the center segregation level, the lower the center segregation of the steel.

[0093] According to GB / T6394-2017 "Method for Determination of Average Grain Size of Metals", the grain size level of the sample is tested, and the higher the grain size level, the smaller the grain size of the steel.

[0094] Table 1 Test Results

[0095]

[0096]

[0097] As shown in Table 1, the steel obtained by the processing technology of this application has high tensile strength, elongation, and reduction of area. The tensile strength is 1406-1425 MPa, the elongation is 17.0-18.5%, and the reduction of area is 42.5-46.5%, exhibiting excellent mechanical properties. Furthermore, it also has a high sorbite content, small grain size, and low central segregation. The sorbite content is 95-97%, the grain size is 9.0-9.4, and the central segregation is 0, demonstrating the characteristics of high sorbite content and small grain size, resulting in a more uniform steel structure, higher quality, and meeting higher requirements.

[0098] Comparing Comparative Examples 1, 2, 3, and 5, it can be seen that adding Cr and V to the chemical composition of molten steel simultaneously is beneficial to increasing the quality of the steel. Comparing Comparative Examples 1, 2, 4, and 6, it can be seen that adding Cr and La to the chemical composition of molten steel simultaneously is also beneficial to increasing the quality of the steel. Comparing Comparative Examples 1, 3, 4, and 7, it can be seen that adding V and La to the chemical composition of molten steel simultaneously is also beneficial to increasing the quality of the steel. Combined with Example 1, it can be seen that adding Cr, V, and La to the chemical composition of molten steel simultaneously can greatly increase the tensile strength and sorbite content of the steel, thereby improving the quality of the steel.

[0099] Comparing Example 1 and Comparative Example 8, it can be seen that when the V content in the molten steel is lower than the limit specified in this application, the tensile strength, sorbite ratio, and grain size are all reduced. Therefore, when the V content in the molten steel is within the limit specified in this application, the steel can be guaranteed to have good performance.

[0100] Comparing Example 1 and Comparative Example 9, it can be seen that in step S1, the liquid core in the primary product is continuously electromagnetically stirred throughout the continuous casting process, which is beneficial to improving the performance of the steel. Furthermore, combining this with Comparative Example 10, it can be seen that in step S4, rapid cooling, slow cooling, heating, and rapid cooling, through their interplay, can increase the mechanical properties, sorbite content, and grain size of the steel, resulting in superior performance.

[0101] It should be noted that the embodiments described above are only for explaining this application and do not constitute any limitation on this application. This application has been described with reference to typical embodiments, but it should be understood that the terms used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to this application within the scope of the claims, and revisions can be made to the invention without departing from the scope and spirit of this application. Although the application described herein relates to specific methods, materials, and embodiments, it does not mean that this application is limited to the specific examples disclosed herein; on the contrary, this application can be extended to all other methods and applications with the same function.

Claims

1. A processing technology for high-strength, smooth, prestressed stranded steel, characterized in that: Includes the following steps: S1. Continuous casting: Molten steel is poured into the tundish and then transferred to the crystallizer for primary cooling. The molten steel cools along the inner wall of the crystallizer and forms a primary product with molten steel as the liquid core and the surrounding walls as the billet. The primary product is then pulled out from the crystallizer outlet, and the liquid core in the primary product is cooled a second time to obtain the billet. Throughout the continuous casting process, the molten steel is always protected with protective slag, and the liquid core in the initial product is always electromagnetically stirred; the frequency of electromagnetic stirring is 8-12Hz. Furthermore, the molten steel is mainly composed of the following chemical components by weight percentage: C: 0.81-0.85%, Si: 0.25-0.35%, Mn: 0.72-0.82%, Cr: 0.22-0.30%, V: 0.09-0.11%, La: 0.15-0.22%, Ni≤0.1%, Cu≤0.20%, P≤0.025%, S≤0.025%, N≤0.005%, O≤0.001%, H≤0.0002%, with the balance being Fe; S2. Heating: Under blast furnace gas and a positive pressure of 15-25 Pa, the billet is heated to 590-610℃ and held for 30-50 min. Then, the temperature is raised to 890-910℃ and held for 30-50 min. After that, the temperature is raised to 1160-1180℃ and held for 30-50 min to obtain a hot billet. S3. Rolling: The hot billet is rolled at an initial rolling temperature of 980-1000℃, a finishing rolling temperature of 910-930℃, and a wire drawing temperature of 850-870℃ to obtain a semi-finished product. S4. Cooling: The semi-finished product is cooled to 655-665℃ at a rate of 14-16℃ / s, then cooled to 450-470℃ at a rate of 1-3℃ / s, then heated to 635-645℃, then cooled to 290-310℃ at a rate of 14-16℃ / s, and finally cooled to room temperature to obtain steel.

2. The processing technology of high-strength smooth prestressed stranded steel according to claim 1, characterized in that: The molten steel is mainly composed of the following chemical components by weight percentage: C: 0.83%, Si: 0.30%, Mn: 0.77%, Cr: 0.26%, V: 0.10%, La: 0.18%, Ni≤0.1%, Cu≤0.20%, P≤0.025%, S≤0.025%, N≤0.005%, O≤0.001%, H≤0.0002%, with the balance being Fe.

3. The processing technology for high-strength smooth prestressed stranded wire steel according to claim 1, characterized in that: In step S1, the initial product is pulled out of the crystallizer at a speed of 1.0-1.2 m / min.

4. The processing technology for high-strength smooth prestressed stranded wire steel according to claim 1, characterized in that: In step S1, the thickness of the billet wall at the outlet of the crystallizer of the initial product is 19.52-21.34 mm and the liquid core depth is 12.31-14.90 mm.

5. The processing technology of high-strength smooth prestressed stranded steel according to claim 1, characterized in that: The billet is a square billet with a square cross-section and a side length of 130-160mm.

6. The processing technology of high-strength smooth prestressed stranded steel according to claim 1, characterized in that: The superheating temperature of the molten steel is 15-25℃.

7. The processing technology of high-strength smooth prestressed stranded steel according to claim 1, characterized in that: The diameter of the steel is 6.5-10mm.

8. A type of steel, characterized in that: The steel is manufactured using the processing technology for high-strength smooth prestressed stranded wire as described in any one of claims 1-7.

9. A high-strength, smooth, prestressed stranded wire, characterized in that: It comprises multiple steel bars, which are twisted together, and the steel bars are the steel bars as described in claim 8.

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