A method for producing wire rod for 1860MPa grade rare earth steel strand

Abstract

This invention discloses a method for producing 1860MPa grade rare earth steel strand wire rod, comprising: smelting process; continuous casting process; rolling process: billet heating; controlled rolling parameters; controlled cooling process; the chemical composition of the wire rod by weight percentage is: C: 0.80-0.84%, Si: 0.20-0.30%, Mn: 0.75-0.85%, Cr: 0.18-0.22%, P≤0.015%, S≤0.010%, Ce: 0.002-0.004%, La: 0.001-0.002%, Al: 0.02-0.04%, Cu≤0.02%, As≤0.01%, O≤0.0015%, N≤0.008%, with the balance being Fe and unavoidable impurities; wherein the Si / Cr ratio is 0.9-1.7. The purpose of this invention is to achieve stable and compliant mechanical properties, improved production efficiency and environmental friendliness, and controllable costs through synergistic optimization of components and processes.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and in particular relates to a method for producing wire rods for 1860MPa grade rare earth steel strands. Background Technology

[0002] 1860MPa grade steel strand, as a core load-bearing material in bridges, large-scale buildings, and other engineering projects, directly depends on the metallurgical quality and microstructure uniformity of the raw wire rod. Existing wire rod production technology has the following shortcomings:

[0003] Unreasonable composition design: Traditional processes fail to achieve a synergistic ratio of rare earth and microalloying elements, or rely solely on VN microalloying and high Cu content design, resulting in severe segregation in the core of the wire rod, with segregation indices of elements such as carbon and manganese exceeding 1.08, and a core breakage rate of over 18% during drawing; Insufficient control of harmful elements leads to the enrichment of residual elements such as Cu and As at grain boundaries, causing type II temper embrittlement and reducing the toughness of the wire rod.

[0004] Insufficient purity of molten steel: The raw materials are mixed, and the deoxidation and desulfurization processes during smelting are poorly controlled. The inclusion grades of Class A and Class B are 1.5-2.0. These inclusions become stress concentration points, increasing the risk of wire breakage during drawing.

[0005] Defects in rolling and controlled cooling processes: large fluctuations in heating temperature and a temperature difference of over 30°C in the bar lead to coarse austenite grains; the Stellmore air-cooling line has a single cooling rate control, with a sorbite conversion rate of only 80%-85%, and is prone to generating abnormal structures such as martensite and network cementite, causing fluctuations in the mechanical properties of the wire rod, with tensile strength deviations reaching ±50MPa and area reduction of less than 28%, which cannot meet the drawing and forming requirements of 1860MPa grade steel strand.

[0006] Environmental and cost issues: Some processes use lead bath and salt bath heat treatment, which leads to waste liquid pollution and high energy consumption. The energy consumption per ton of steel is ≥150kw·h, which does not meet the requirements of green production. Summary of the Invention

[0007] The purpose of this invention is to provide a method for producing wire rod for 1860MPa grade rare earth steel strand, and to solve the following technical problems:

[0008] The high wire breakage rate and insufficient toughness are caused by segregation in the core of the wire rod and the enrichment of harmful elements.

[0009] The problem of low purity of molten steel and excessive levels of inclusions affecting structural continuity;

[0010] The problem of fluctuating mechanical properties caused by poor microstructure uniformity and low sorbite conversion rate;

[0011] Traditional processes suffer from high pollution and high energy consumption.

[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0013] This invention discloses a method for producing 1860MPa grade rare earth steel strand wire rod, comprising:

[0014] Smelting process:

[0015] Hot metal pretreatment: desulfurization to S≤0.005%, slag removal rate≥95%;

[0016] Converter smelting: final carbon is controlled at 0.08~0.12%, tapping temperature is 1620~1650℃, and deoxidation is carried out using silicon-manganese alloy and aluminum-manganese alloy;

[0017] LF furnace refining: refining time ≥ 40 min, white slag holding time ≥ 20 min, add rare earth alloy (Ce-La composite alloy) for microalloying treatment, and adjust the steel composition to the target range;

[0018] Continuous casting process: 150×150mm square billet is used, the superheat of continuous casting is controlled at 15-25℃, the electromagnetic stirring current of the crystallizer is 250-350A, and the casting speed is 2.0-2.2m / min;

[0019] Rolling process:

[0020] Billet heating: heating temperature 1050-1100℃, soaking time 100-130min, temperature difference of the billet ≤25℃;

[0021] Controlled rolling parameters: initial rolling temperature 920-960℃, finishing rolling inlet temperature 880-920℃, sizing and reducing inlet temperature 850-880℃, wire drawing temperature 840-870℃;

[0022] Cooling process: The Stellmore air-cooled line adopts a three-stage cooling system of "strong cooling - weak cooling - slow cooling". The first stage is from 870°C to 700°C with a cooling rate of 8-10°C / s. The second stage is from 700°C to 650°C with a cooling rate of 3-5°C / s. The third stage starts at 650°C with a cooling rate of 1-2°C / s. After cooling to 550-600°C, the line enters the insulation corridor for 120-180 minutes of insulation.

[0023] The chemical composition of the wire rod by weight percentage is as follows: C: 0.80-0.84%, Si: 0.20-0.30%, Mn: 0.75-0.85%, Cr: 0.18-0.22%, P≤0.015%, S≤0.010%, Ce: 0.002-0.004%, La: 0.001-0.002%, Al: 0.02-0.04%, Cu≤0.02%, As≤0.01%, O≤0.0015%, N≤0.008%, with the balance being Fe and unavoidable impurities; wherein the Si / Cr ratio is 0.9-1.7.

[0024] Furthermore, the chemical composition of the wire rod by weight percentage is as follows: C: 0.82%, Si: 0.25%, Mn: 0.80%, Cr: 0.20%, P: 0.012%, S: 0.008%, Ce: 0.003%, La: 0.0015%, Al: 0.03%, Cu: 0.015%, As: 0.009%, O: 0.0012%, N: 0.006%, with the balance being Fe and unavoidable impurities; Si / Cr = 1.25, Ce+La = 0.0045%.

[0025] Furthermore, the chemical composition of the wire rod by weight percentage is as follows: C: 0.81%, Si: 0.22%, Mn: 0.78%, Cr: 0.19%, P: 0.010%, S: 0.007%, Ce: 0.0025%, La: 0.0012%, Al: 0.025%, Cu: 0.012%, As: 0.008%, O: 0.0010%, N: 0.005%, with the balance being Fe and unavoidable impurities; Si / Cr = 1.16, Ce+La = 0.0037%.

[0026] Furthermore, the chemical composition of the wire rod by weight percentage is as follows: C: 0.83%, Si: 0.28%, Mn: 0.83%, Cr: 0.21%, P: 0.014%, S: 0.009%, Ce: 0.0038%, La: 0.0018%, Al: 0.035%, Cu: 0.018%, As: 0.0095%, O: 0.0013%, N: 0.007%, Si / Cr = 1.33, Ce+La = 0.0056%.

[0027] Furthermore, specifically including:

[0028] Hot metal pretreatment: desulfurization to S=0.004%, slag removal rate 96%;

[0029] Converter smelting: final carbon 0.10%, tapping temperature 1635℃, deoxidation with silicon-manganese alloy + aluminum-manganese alloy;

[0030] LF furnace refining: refining time 45 min, white slag maintained for 25 min, Ce-La composite alloy added to adjust composition;

[0031] Continuous casting: 150×150mm square billet, superheat 20℃, electromagnetic stirring current 300A, casting speed 2.1m / min;

[0032] Rolling: Heating temperature 1080℃, soaking time 115min, temperature difference of the through bar 22℃; initial rolling temperature 940℃, finishing rolling inlet temperature 900℃, sizing and reducing inlet temperature 860℃, wire drawing temperature 855℃.

[0033] Cooling control: The first stage is from 855℃ to 700℃ with a cooling rate of 9℃ / s; the second stage is from 700℃ to 650℃ with a cooling rate of 4℃ / s; the third stage starts at 650℃ with a cooling rate of 1.5℃ / s and cools to 580℃ before holding for 150 minutes.

[0034] Product performance: sorbite conversion rate 92%, tensile strength 1320MPa, yield strength 1180MPa, elongation 32%, reduction of area 40%, tensile strength fluctuation 35MPa, inclusion grade 0.8, and wire breakage rate 1.5%.

[0035] Furthermore, specifically including:

[0036] Hot metal pretreatment: desulfurization to S=0.003%, slag removal rate 97%;

[0037] Converter smelting: final carbon 0.09%, tapping temperature 1625℃, deoxidation of silicon-manganese alloy + aluminum-manganese alloy;

[0038] LF furnace refining: refining time 42 min, white slag maintained for 22 min, Ce-La composite alloy added to adjust composition;

[0039] Continuous casting: 150×150mm square billet, superheat 18℃, electromagnetic stirring current 280A, casting speed 2.1m / min;

[0040] Rolling: Heating temperature 1060℃, soaking time 105min, temperature difference of the through bar 20℃; initial rolling temperature 930℃, finishing rolling inlet temperature 890℃, sizing and reducing inlet temperature 850℃, wire drawing temperature 845℃.

[0041] Cooling control: The first stage is from 845℃ to 700℃ with a cooling rate of 8.5℃ / s; the second stage is from 700℃ to 650℃ with a cooling rate of 3.5℃ / s; the third stage starts at 650℃ with a cooling rate of 1.2℃ / s; after cooling to 560℃, the temperature is held for 140 minutes.

[0042] Product performance: sorbite conversion rate 91%, tensile strength 1300MPa, yield strength 1160MPa, elongation 31%, reduction of area 39%, tensile strength fluctuation 32MPa, inclusion grade 0.7, and wire breakage rate 1.2%.

[0043] Furthermore, specifically including:

[0044] Hot metal pretreatment: desulfurization to S=0.005%, slag removal rate 95%;

[0045] Converter smelting: final carbon 0.11%, tapping temperature 1640℃, deoxidation with silicon-manganese alloy + aluminum-manganese alloy;

[0046] LF furnace refining: refining time 48 min, white slag maintained for 28 min, Ce-La composite alloy added to adjust composition;

[0047] Continuous casting: 150×150mm square billet, superheat 23℃, electromagnetic stirring current 320A, casting speed 2.1m / min;

[0048] Rolling: Heating temperature 1090℃, soaking time 125min, temperature difference of the through bar 24℃; initial rolling temperature 950℃, finishing rolling inlet temperature 910℃, sizing and reducing inlet temperature 870℃, wire drawing temperature 865℃.

[0049] Cooling control: The first stage is from 865℃ to 700℃ with a cooling rate of 9.5℃ / s; the second stage is from 700℃ to 650℃ with a cooling rate of 4.5℃ / s; the third stage starts at 650℃ with a cooling rate of 1.8℃ / s; after cooling to 590℃, the temperature is held for 160 minutes.

[0050] Product performance: sorbite conversion rate 93%, tensile strength 1340MPa, yield strength 1200MPa, elongation 33%, reduction of area 41%, tensile strength fluctuation 38MPa, inclusion grade 0.9, and wire breakage rate 1.8%.

[0051] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0052] Synergistic optimization of composition and process effectively improves billet quality: Rare earth elements Ce and La combine with O and S in steel to form fine and dispersed rare earth oxides and sulfides, replacing harmful inclusions such as Al2O3 and MnS, reducing the inclusion grade to 0.5-1.0, while suppressing element segregation with a segregation index ≤1.03, and eliminating abnormal structures such as martensite in the core; the 150×150mm small cross-section square billet has a fast solidification rate, further reducing the risk of segregation, and with appropriate continuous casting parameters, the internal quality of the billet is more uniform.

[0053] Stable and compliant mechanical properties: sorbite conversion rate of wire rod ≥90%, tensile strength 1280-1350MPa, yield strength ≥1150MPa, elongation ≥30%, reduction of area ≥38%, tensile strength fluctuation ≤40MPa, meeting the drawing requirements of 1860MPa grade steel strand (Explanation: 1860MPa is the strength level of the finished steel strand after drawing; the example is the performance of the base wire rod), drawing breakage rate ≤2%; Cr content is precisely controlled at 0.18-0.22%, ensuring the strengthening effect while avoiding the decrease in toughness caused by excessive Cr.

[0054] Improved production efficiency and environmental friendliness: The use of 150×150mm small cross-section square billets and adapted casting speed increases continuous casting efficiency by more than 20%; the one-fire forming and three-stage controlled cooling process eliminates the need for lead bath / salt bath heat treatment, reducing energy consumption per ton of steel to ≤100kw・h, with no waste liquid discharge, meeting green production standards.

[0055] Cost controllable: Reduce the amount of Cr element (0.18-0.22%), shorten the heating and homogenization time by using small cross-section square billets, and combine with precise proportion of rare earth elements to significantly reduce raw material and energy costs while ensuring performance. Detailed Implementation

[0056] Example 1

[0057] Chemical composition (mass percentage): C: 0.82%, Si: 0.25%, Mn: 0.80%, Cr: 0.20%, P: 0.012%, S: 0.008%, Ce: 0.003%, La: 0.0015%, Al: 0.03%, Cu: 0.015%, As: 0.009%, O: 0.0012%, N: 0.006%, Si / Cr = 1.25, Ce + La = 0.0045%; the remainder is Fe and impurities.

[0058] Production process:

[0059] Hot metal pretreatment: desulfurization to S=0.004%, slag removal rate 96%;

[0060] Converter smelting: final carbon 0.10%, tapping temperature 1635℃, deoxidation of silicon-manganese alloy + aluminum-manganese alloy;

[0061] LF furnace refining: refining time 45 min, white slag maintained for 25 min, Ce-La composite alloy added to adjust composition;

[0062] Continuous casting: 150×150mm square billet, superheat 20℃, electromagnetic stirring current 300A, casting speed 2.1m / min;

[0063] Rolling: Heating temperature 1080℃, soaking time 115min, temperature difference of the through bar 22℃; initial rolling temperature 940℃, finishing rolling inlet temperature 900℃, sizing and reducing inlet temperature 860℃, wire drawing temperature 855℃.

[0064] Cooling control: The first stage is from 855℃ to 700℃ with a cooling rate of 9℃ / s; the second stage is from 700℃ to 650℃ with a cooling rate of 4℃ / s; the third stage starts at 650℃ with a cooling rate of 1.5℃ / s. The cooling rate for the first stage is 9℃ / s (fan frequency 55Hz), the cooling rate for the second stage is 4℃ / s (fan frequency 35Hz), and the cooling rate for the third stage is 1.5℃ / s (fan frequency 18Hz). After cooling to 580℃, the temperature is maintained for 150 minutes.

[0065] Product performance: sorbite conversion rate 92%, tensile strength 1320MPa, yield strength 1180MPa, elongation 32%, reduction of area 40%, tensile strength fluctuation 35MPa, inclusion grade 0.8, and wire breakage rate 1.5%.

[0066] Example 2

[0067] Chemical composition (mass percentage): C: 0.81%, Si: 0.22%, Mn: 0.78%, Cr: 0.19%, P: 0.010%, S: 0.007%, Ce: 0.0025%, La: 0.0012%, Al: 0.025%, Cu: 0.012%, As: 0.008%, O: 0.0010%, N: 0.005%, Si / Cr = 1.16, Ce + La = 0.0037%; the remainder is Fe and impurities.

[0068] Production process:

[0069] Hot metal pretreatment: desulfurization to S=0.003%, slag removal rate 97%;

[0070] Converter smelting: final carbon 0.09%, tapping temperature 1625℃, deoxidation of silicon-manganese alloy + aluminum-manganese alloy;

[0071] LF furnace refining: refining time 42 min, white slag maintained for 22 min, Ce-La composite alloy added to adjust composition;

[0072] Continuous casting: 150×150mm square billet, superheat 18℃, electromagnetic stirring current 280A, casting speed 2.1m / min;

[0073] Rolling: Heating temperature 1060℃, soaking time 105min, temperature difference of the through bar 20℃; initial rolling temperature 930℃, finishing rolling inlet temperature 890℃, sizing and reducing inlet temperature 850℃, wire drawing temperature 845℃.

[0074] Cooling control: The first stage cools from 845℃ to 700℃ at a rate of 8.5℃ / s; the second stage cools from 700℃ to 650℃ at a rate of 3.5℃ / s; and the third stage cools from 650℃ onwards at a rate of 1.2℃ / s. The cooling rate for the first stage is 8.5℃ / s (fan frequency 52Hz), the second stage cools at a rate of 3.5℃ / s (fan frequency 32Hz), and the third stage cools at a rate of 1.2℃ / s (fan frequency 16Hz). After cooling to 560℃, the temperature is maintained for 140 minutes.

[0075] Product performance: sorbite conversion rate 91%, tensile strength 1300MPa, yield strength 1160MPa, elongation 31%, reduction of area 39%, tensile strength fluctuation 32MPa, inclusion grade 0.7, and wire breakage rate 1.2%.

[0076] Example 3

[0077] Chemical composition (mass percentage): C: 0.83%, Si: 0.28%, Mn: 0.83%, Cr: 0.21%, P: 0.014%, S: 0.009%, Ce: 0.0038%, La: 0.0018%, Al: 0.035%, Cu: 0.018%, As: 0.0095%, O: 0.0013%, N: 0.007%, Si / Cr = 1.33, Ce + La = 0.0056%; the remainder is Fe and impurities.

[0078] Production process:

[0079] Hot metal pretreatment: desulfurization to S=0.005%, slag removal rate 95%;

[0080] Converter smelting: final carbon 0.11%, tapping temperature 1640℃, deoxidation with silicon-manganese alloy + aluminum-manganese alloy;

[0081] LF furnace refining: refining time 48 min, white slag maintained for 28 min, Ce-La composite alloy added to adjust composition;

[0082] Continuous casting: 150×150mm square billet, superheat 23℃, electromagnetic stirring current 320A, casting speed 2.1m / min;

[0083] Rolling: Heating temperature 1090℃, soaking time 125min, temperature difference of the through bar 24℃; initial rolling temperature 950℃, finishing rolling inlet temperature 910℃, sizing and reducing inlet temperature 870℃, wire drawing temperature 865℃.

[0084] Cooling control: The first stage cools from 865℃ to 700℃ at a rate of 9.5℃ / s, the second stage cools from 700℃ to 650℃ at a rate of 4.5℃ / s, and the third stage starts at 650℃ at a rate of 1.8℃ / s. The cooling rate for the first stage is 9.5℃ / s (fan frequency 58Hz), the second stage cools at a rate of 4.5℃ / s (fan frequency 38Hz), and the third stage cools at a rate of 1.8℃ / s (fan frequency 19Hz). After cooling to 590℃, the temperature is maintained for 160 minutes.

[0085] Product performance: sorbite conversion rate 93%, tensile strength 1340MPa, yield strength 1200MPa, elongation 33%, reduction of area 41%, tensile strength fluctuation 38MPa, inclusion grade 0.9, and wire breakage rate 1.8%.

[0086] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A process for the production of a wire rod for 1860 MPa grade rare earth steel strand, characterized by, include: Smelting process: Hot metal pretreatment: desulfurization to S≤0.005%, slag removal rate≥95%; Converter smelting: final carbon is controlled at 0.08~0.12%, tapping temperature is 1620~1650℃, and deoxidation is carried out using silicon-manganese alloy and aluminum-manganese alloy; LF furnace refining: refining time ≥ 40 min, white slag holding time ≥ 20 min, add rare earth alloy (Ce-La composite alloy) for microalloying treatment, and adjust the steel composition to the target range; Continuous casting process: 150×150mm square billet is used, the superheat of continuous casting is controlled at 15-25℃, the electromagnetic stirring current of the crystallizer is 250-350A, and the casting speed is 2.0-2.2m / min; Rolling process: Billet heating: heating temperature 1050-1100℃, soaking time 100-130min, temperature difference of the billet ≤25℃; Controlled rolling parameters: initial rolling temperature 920-960℃, finishing rolling inlet temperature 880-920℃, sizing and reducing inlet temperature 850-880℃, wire drawing temperature 840-870℃; Cooling process: The Stellmore air-cooled line adopts a three-stage cooling system of "strong cooling - weak cooling - slow cooling". The first stage is from 870°C to 700°C with a cooling rate of 8-10°C / s. The second stage is from 700°C to 650°C with a cooling rate of 3-5°C / s. The third stage starts at 650°C with a cooling rate of 1-2°C / s. After cooling to 550-600°C, the line enters the insulation corridor for insulation for 120-180 minutes. The chemical composition of the wire rod by weight percentage is as follows: C: 0.80-0.84%, Si: 0.20-0.30%, Mn: 0.75-0.85%, Cr: 0.18-0.22%, P≤0.015%, S≤0.010%, Ce: 0.002-0.004%, La: 0.001-0.002%, Al: 0.02-0.04%, Cu≤0.02%, As≤0.01%, O≤0.0015%, N≤0.008%, with the balance being Fe and unavoidable impurities; The Si / Cr ratio is 0.9-1.

7.

2. A process for producing a wire rod for 1860 MPa grade rare earth steel strand as claimed in claim 1, wherein, The chemical composition of the wire rod by weight percentage is as follows: C: 0.82%, Si: 0.25%, Mn: 0.80%, Cr: 0.20%, P: 0.012%, S: 0.008%, Ce: 0.003%, La: 0.0015%, Al: 0.03%, Cu: 0.015%, As: 0.009%, O: 0.0012%, N: 0.006%, with the balance being Fe and unavoidable impurities; Si / Cr = 1.25, Ce+La = 0.0045%.

3. The method for producing 1860MPa grade rare earth steel strand wire rod according to claim 1, characterized in that, The chemical composition of the wire rod by weight percentage is as follows: C: 0.81%, Si: 0.22%, Mn: 0.78%, Cr: 0.19%, P: 0.010%, S: 0.007%, Ce: 0.0025%, La: 0.0012%, Al: 0.025%, Cu: 0.012%, As: 0.008%, O: 0.0010%, N: 0.005%, with the balance being Fe and unavoidable impurities; Si / Cr=1.16, Ce+La=0.0037%.

4. The method for producing 1860MPa grade rare earth steel strand wire rod according to claim 1, characterized in that, The chemical composition of the wire rod by weight percentage is as follows: C: 0.83%, Si: 0.28%, Mn: 0.83%, Cr: 0.21%, P: 0.014%, S: 0.009%, Ce: 0.0038%, La: 0.0018%, Al: 0.035%, Cu: 0.018%, As: 0.0095%, O: 0.0013%, N: 0.007%, Si / Cr = 1.33, Ce+La = 0.0056%.

5. The method for producing 1860MPa grade rare earth steel strand wire rod according to claim 2, characterized in that, Specifically, it includes: Hot metal pretreatment: desulfurization to S=0.004%, slag removal rate 96%; Converter smelting: final carbon 0.10%, tapping temperature 1635℃, deoxidation with silicon-manganese alloy + aluminum-manganese alloy; LF furnace refining: refining time 45 min, white slag maintained for 25 min, Ce-La composite alloy added to adjust composition; Continuous casting: 150×150mm square billet, superheat 20℃, electromagnetic stirring current 300A, casting speed 2.1m / min; Rolling: Heating temperature 1080℃, soaking time 115min, temperature difference of the through bar 22℃; initial rolling temperature 940℃, finishing rolling inlet temperature 900℃, sizing and reducing inlet temperature 860℃, wire drawing temperature 855℃. Cooling control: The first stage is from 855℃ to 700℃ with a cooling rate of 9℃ / s; the second stage is from 700℃ to 650℃ with a cooling rate of 4℃ / s; the third stage starts at 650℃ with a cooling rate of 1.5℃ / s; after cooling to 580℃, the temperature is held for 150 minutes. Product performance: sorbite conversion rate 92%, tensile strength 1320MPa, yield strength 1180MPa, elongation 32%, reduction of area 40%, tensile strength fluctuation 35MPa, inclusion grade 0.8, and wire breakage rate 1.5%.

6. The method for producing 1860MPa grade rare earth steel strand wire rod according to claim 3, characterized in that, Specifically, it includes: Hot metal pretreatment: desulfurization to S=0.003%, slag removal rate 97%; Converter smelting: final carbon 0.09%, tapping temperature 1625℃, deoxidation of silicon-manganese alloy + aluminum-manganese alloy; LF furnace refining: refining time 42 min, white slag maintained for 22 min, Ce-La composite alloy added to adjust composition; Continuous casting: 150×150mm square billet, superheat 18℃, electromagnetic stirring current 280A, casting speed 2.1m / min; Rolling: Heating temperature 1060℃, soaking time 105min, temperature difference of the through bar 20℃; initial rolling temperature 930℃, finishing rolling inlet temperature 890℃, sizing and reducing inlet temperature 850℃, wire drawing temperature 845℃. Cooling control: The first stage is from 845℃ to 700℃ with a cooling rate of 8.5℃ / s; the second stage is from 700℃ to 650℃ with a cooling rate of 3.5℃ / s; the third stage starts at 650℃ with a cooling rate of 1.2℃ / s; after cooling to 560℃, the temperature is held for 140 minutes. Product performance: sorbite conversion rate 91%, tensile strength 1300MPa, yield strength 1160MPa, elongation 31%, reduction of area 39%, tensile strength fluctuation 32MPa, inclusion grade 0.7, and wire breakage rate 1.2%.

7. The method for producing 1860MPa grade rare earth steel strand wire rod according to claim 4, characterized in that, Specifically, it includes: Hot metal pretreatment: desulfurization to S=0.005%, slag removal rate 95%; Converter smelting: final carbon 0.11%, tapping temperature 1640℃, deoxidation with silicon-manganese alloy + aluminum-manganese alloy; LF furnace refining: refining time 48 min, white slag maintained for 28 min, Ce-La composite alloy added to adjust composition; Continuous casting: 150×150mm square billet, superheat 23℃, electromagnetic stirring current 320A, casting speed 2.1m / min; Rolling: Heating temperature 1090℃, soaking time 125min, temperature difference of the through bar 24℃; initial rolling temperature 950℃, finishing rolling inlet temperature 910℃, sizing and reducing inlet temperature 870℃, wire drawing temperature 865℃. Cooling control: The first stage is from 865℃ to 700℃ with a cooling rate of 9.5℃ / s; the second stage is from 700℃ to 650℃ with a cooling rate of 4.5℃ / s; the third stage starts at 650℃ with a cooling rate of 1.8℃ / s; after cooling to 590℃, the temperature is held for 160 minutes. Product performance: sorbite conversion rate 93%, tensile strength 1340MPa, yield strength 1200MPa, elongation 33%, reduction of area 41%, tensile strength fluctuation 38MPa, inclusion grade 0.9, and wire breakage rate 1.8%.