ULTRA-THIN ULTRA-HIGH STRENGTH STEEL WIRE, WIRE ROD AND METHOD OF PRODUCING WIRE ROD

Abstract

The present invention reveals an ultra-thin ultra-high strength steel wire, a wire rod for an ultra-thin ultra-high strength steel wire and its producing method. The chemical components of the wire rod comprise in percentage by mass: C 0.90˜0.96%, Si 0.12˜0.30%, Mn 0.30˜0.65%, Cr 0.10˜0.30%, Al≤0.004%, Ti≤0.001%, Cu≤0.01%, Ni≤0.01%, S≤0.01%, P≤0.01%, O≤0.0006%, N≤0.0006%, and the balance is Fe and unavoidable impurity elements. The wire rod for the ultra-thin ultra-high strength steel wire may be used as a base material for producing the ultra-thin ultra-high strength steel wire having a diameter in a range of 50˜60 μm and a tensile strength larger than or equal to 4500 MPa.

Claims

1. A wire rod for an ultra-thin ultra-high strength steel wire, wherein chemical components of the wire rod comprise in percentage by mass: C 0.90˜0.96%, Si 0.12˜0.30%, Mn 0.30˜0.65%, Cr 0.10˜0.30%, Al≤0.004%, Ti≤0.001%, Cu≤0.01%, Ni≤0.01%, S≤0.01%, P≤0.01%, O≤0.0006%, N≤0.0006%, and the balance is Fe and unavoidable impurity elements.

2. The wire rod for an ultra-thin ultra-high strength steel wire according to claim 1, wherein the chemical components of the wire rod comprise in percentage by mass: C 0.90˜0.94%, Si 0.12˜0.30%, Mn 0.30˜0.65%, Cr 0.10˜0.30%, Al≤0.004%, Ti≤0.001%, Cu≤0.01%, Ni≤0.01%, S≤0.01%, P≤0.01%, O≤0.0006%, N≤0.0006%, and the balance is Fe and unavoidable impurity elements.

3. The wire rod for an ultra-thin ultra-high strength steel wire according to claim 1, wherein a size of the inclusion in the wire rod is less than or equal to 4 μm, and an average density of a brittle inclusion in the wire rod is less than or equal to 2/mm.sup.2.

4. The wire rod for an ultra-thin ultra-high strength steel wire according to claim 1, wherein a diameter of the wire rod is 5.5 mm.

5. The wire rod for an ultra-thin ultra-high strength steel wire according to claim 1, wherein the wire rod for the ultra-thin ultra-high strength steel wire has a sorbite rate larger than or equal to 95%, an area reduction rate larger than or equal to 40%, and a tensile strength larger than or equal to 1300 MPa.

6. An ultra-thin ultra-high strength steel wire, wherein the ultra-thin ultra-high strength steel wire is fabricated from the wire rod for the ultra-thin ultra-high strength steel wire according to claim 1 as a base material.

7. The ultra-thin ultra-high strength steel wire according to claim 6, wherein the steel wire has a diameter in a range of 50˜60 μm, a tensile strength larger than or equal to 4500 MPa, and a mileage of continuous wire without break longer than or equal to 300 km during fabrication by drawing.

8. A method of producing a wire rod for an ultra-thin ultra-high strength steel wire, wherein the method comprises the following steps: smelting: melting a charge into molten steel in a vacuum induction smelting furnace, refining the molten steel and regulating chemical components and inclusions in molten steel, and pouring the molten steel and casting to obtain a steel ingot; remelting: crystallizing and remelting the steel ingot to obtain a remelted ingot; forging: performing a homogenization thermal process for the remelted ingot, and then performing forging to obtain a billet; steel rolling: rolling the billet at a temperature in a range of 900˜1100° C. to fabricate the wire rod for the ultra-thin ultra-high strength steel wire, where the chemical components of the wire rod for the ultra-thin ultra-high strength steel wire comprises in percentage by mass: C 0.90˜0.96%, Si 0.12˜0.30%, Mn 0.30˜0.65%, Cr 0.10˜0.30%, Al≤0.004%, Ti≤0.001%, Cu≤0.01%, Ni≤0.01%, S≤0.01%, P≤0.01%, O≤0.0006%, N≤0.0006%, and the balance is Fe and unavoidable impurity elements.

9. The method of producing a wire rod for an ultra-thin ultra-high strength steel wire according to claim 8, wherein the remelting step comprises electroslag remelting, or/and vacuum consumable remelting.

10. The method of producing a wire rod for an ultra-thin ultra-high strength steel wire according to claim 9, wherein in the electroslag remelting step, the chemical components of the slag comprise in percentage by mass: CaO 6˜14%, Al.sub.2O.sub.3 8˜15%, SiO.sub.2 20˜28%, MgO <5%, and the balance is CaF.sub.2; in the electroslag remelting step, the chemical components of the slag comprise in percentage by mass: CaO 10%, Al.sub.2O.sub.310%, SiO.sub.2 25%, and the balance is CaF.sub.2.

11. The method of producing a wire rod for an ultra-thin ultra-high strength steel wire according to claim 9, wherein in the electroslag remelting step, the melting speed is in a range of 6.5˜7.5 kg/min.

12. The method of producing a wire rod for an ultra-thin ultra-high strength steel wire according to claim 9, wherein the electroslag remelting step comprises the following in order: a slag-forming stage; a pressure-controlling stage: controlling the pressure of the smelting furnace to a range of 2˜5 MPa, and making the pressure of cooling water in a crystallizer in a range of 2˜5 MPa; an electroslag smelting stage: the voltage is in a range of 35˜38V, the electrical current is in a range of 8500˜9500 A, the temperature of the cooling water is in a range of 35˜40° C., and the flow of the cooling water is in a range of 130˜150 m.sup.3/h.

13. The method of producing a wire rod for an ultra-thin ultra-high strength steel wire according to claim 9, wherein in the vacuum consumable remelting step, the steel ingot is taken as a consumable electrode rod, and the consumable electrode rod is subjected to vacuum consumable crystallization and then remelting under a degree of vacuum in a range of 0.01˜1 Pa.

14. The method of producing a wire rod for an ultra-thin ultra-high strength steel wire according to claim 9, wherein in the vacuum consumable remelting step, the steel ingot is taken as a consumable electrode rod, remelting is performed after energizing and starting the arc, the voltage for energizing and starting arc is in a range of 20˜26V, and the length of the arc is in a range of 15˜20 mm.

15. The method of producing a wire rod for an ultra-thin ultra-high strength steel wire according to claim 9, wherein in the vacuum consumable remelting step, the melting speed is in a range of 3.5˜4.5 kg/min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1 is a metallographic structure diagram of a wire rod for an ultra-thin ultra-high strength steel wire according to Embodiment 1 of the present invention.

[0043] FIG. 2 is a metallographic structure diagram of a wire rod for an ultra-thin ultra-high strength steel wire according to Embodiment 2 of the present invention.

[0044] FIG. 3 is a metallographic structure diagram of a wire rod for an ultra-thin ultra-high strength steel wire according to Embodiment 3 of the present invention.

DETAILED DESCRIPTION

[0045] One embodiment of the present invention provides a wire rod for an ultra-thin ultra-high strength steel wire, and a method of producing the wire rod for the ultra-thin ultra-high strength steel wire.

[0046] The chemical components of the wire rod for an ultra-thin ultra-high strength steel wire of the present invention comprise in percentage by mass: C 0.90˜0.96%, Si 0.12˜0.30%, Mn 0.30˜0.65%, Cr 0.10˜0.30%, Al≤0.004%, Ti≤0.001%, Cu≤0.01%, Ni≤0.01%, S≤0.01%, P≤0.01%, O≤0.0006%, N≤0.0006%, and the balance is Fe and unavoidable impurity elements.

[0047] Further, the chemical components of the wire rod comprise in percentage by mass: C 0.90˜0.94%, Si 0.12˜0.30%, Mn 0.30˜0.65%, Cr 0.10˜0.30%, Al≤0.004%, Ti≤0.001%, Cu≤0.01%, Ni≤0.01%, S≤0.01%, P≤0.01%, O≤0.0006%, N≤0.0006%, and the balance is Fe and unavoidable impurity elements.

[0048] Furthermore, a size of the inclusion in the wire rod for the ultra-thin ultra-high strength steel wire is less than or equal to 4 μm, and an average density of a brittle inclusion in the wire rod for the ultra-thin ultra-high strength steel wire is less than or equal to 2/mm.sup.2, and a diameter of the wire rod for the ultra-thin ultra-high strength steel wire is 5.5 mm. Besides, it can be proved by numerous experimental studies that the wire rod for the ultra-thin ultra-high strength steel wire has a sorbite rate larger than or equal to 95%, an area reduction rate larger than or equal to 40%, and a tensile strength larger than or equal to 1300 MPa.

[0049] Furthermore, the wire rod for the ultra-thin ultra-high strength steel wire may be used as a base material for producing the ultra-thin ultra-high strength steel wire having a diameter in a range of 50˜60 μm and a tensile strength larger than or equal to 4500 MPa, and during the process of further drawing the wire rod for the ultra-thin ultra-high strength steel wire into the ultra-thin ultra-high strength steel wire with the diameter of 50˜60 μm, the mileage of the resultant continuous wire without break is longer than or equal to 300 km.

[0050] From another perspective, one embodiment of the present invention further provides an ultra-thin ultra-high strength steel wire which is fabricated from the wire rod for the ultra-thin ultra-high strength steel wire as the base material. For example, the ultra-thin ultra-high strength steel wire may be fabricated by performing a step of further drawing the wire rod for the ultra-thin ultra-high strength steel wire, the ultra-thin ultra-high strength steel wire has a diameter in a range of 50˜60 μm and a tensile strength larger than or equal to 4500 MPa, and the mileage of the resultant continuous wire without break during the fabrication by drawing is longer than or equal to 300 km.

[0051] One embodiment of the present invention further provides a method of producing a wire rod for fabricating the ultra-thin ultra-high strength steel wire. As stated above, the production method according to the present invention is obtained according to a lot of experimental research. Steps of the production method will be further described below in conjunction with specific embodiments.

[0052] A First Implementation

[0053] A method of producing a wire rod for fabricating the ultra-thin ultra-high strength steel wire comprises the following steps:

[0054] (1) Smelting Step

[0055] Melting a charge into molten steel in a vacuum induction smelting furnace, refining the molten steel and regulating chemical components and inclusions in molten steel, and pouring the molten steel and casting to obtain a steel ingot.

[0056] Furthermore, after heating to melt the charge until all the charge is melted, filling argon into the smelting chamber until the pressure of the smelting chamber reaches (0.8˜1)×10.sup.4 Pa, stirring for 2-4 min, regulating the temperature to 1540±5° C. and refining. The refining is completed in two times: during the primary refining, after refining 10 min each time, stirring for 2-4 min, and the primary refining lasts 25-40 min; sampling to analyze chemical components and inclusions in the molten steel, then replenishing argon into the smelting chamber until the pressure of the smelting chamber reaches (2.5˜3)×10.sup.4 Pa, adding electrolytic manganese, stirring for 2-4 min, then proceeding to the secondary refining which lasts 15-25 min; sampling and analyzing, removing the inclusions, stirring for 2-4 min, then regulating the temperature to 1600±5° C., and pouring the molten steel and casting to obtain the steel ingot. Adjustment of the chemical components may be performed by adding chemical elements according to the components needed by the final molten steel.

[0057] (2) Remelting Step

[0058] The smelted steel ingot is crystallized and remelted to obtain a remelted ingot.

[0059] Furthermore, the remelting step comprises electroslag remelting step: forging the smelted steel ingot as a base material of a consumable electrode into a consumable electrode rod suitable for an electroslag remelting size of an electroslag furnace, removing a oxide skin from the surface of the consumable electrode rod, laying an arc initiating agent on a water jacket on the bottom of the electroslag furnace so that the consumable electrode rod, the arc initiating agent and the water jacket are in tight contact, baking the slag at a temperature in a range of 600˜800° C. and then starting arc to form the slag, filling argon into the smelting chamber to pressurize the smelting chamber, then starting electroslag smelting, feeding and then lifting the consumable electrode rod and ending the smelting, releasing the pressure, reducing the temperature and then getting out the remelted ingot.

[0060] Preferably, the electroslag remelting step comprises performing the following in order:

[0061] A slag-forming stage;

[0062] A pressure-controlling stage: controlling the pressure of the smelting furnace to a range of 2˜5 MPa, and making the pressure of cooling water in the crystallizer in a range of 2˜5 MPa;

[0063] An electroslag smelting stage: the voltage is in a range of 35˜38V, the electrical current is in a range of 8500˜9500 A, the temperature of the cooling water is in a range of 35˜40° C., and the flow of the cooling water is in a range of 130˜150 m.sup.3/h.

[0064] Preferably, the chemical components of the slag comprise in percentage by mass: CaO 6˜14%, Al.sub.2O.sub.38˜15%, SiO.sub.2 20˜28%, MgO <5%, and the balance is CaF.sub.2.

[0065] Further preferably, the chemical components of the slag comprise in percentage by mass: CaO 10%, Al.sub.2O.sub.310%, SiO.sub.2 25%, and the balance is CaF.sub.2.

[0066] Preferably, the melting speed in the remelting step is in a range of 6.5˜7.5 kg/min.

[0067] (3) A Forging Step

[0068] A homogenization thermal process is performed for the remelted ingot, and then forging is performed to obtain a billet.

[0069] Preferably, the temperature at which the forging is started is in a range of 1140-1160° C., and the temperature at which the forging is finished is in a range of 800-900° C.

[0070] (4) A Steel Rolling Step

[0071] The forged billet is rolled at a temperature in a range of 900˜1100° C. to fabricate the wire rod for the ultra-thin ultra-high strength steel wire. The chemical components of the wire rod for the ultra-thin ultra-high strength steel wire comprises in percentage by mass: C 0.90˜0.96%, Si 0.12˜0.30%, Mn 0.30˜0.65%, Cr 0.10˜0.30%, Al≤0.004%, Ti≤0.001%, Cu≤0.01%, Ni≤0.01%, S≤0.01%, P≤0.01%, O≤0.0006%, N≤0.0006%, and the balance is Fe and unavoidable impurity elements.

[0072] Furthermore, the wire rod for the ultra-thin ultra-high strength steel wire is fabricated as having a diameter of 5.5 mm. The steel rolling step may comprise techniques such as billet heating, hot rolling and Stelmor cooling control.

[0073] Detailed description will be provided below through embodiments.

Embodiment 1

[0074] (1) Smelting

[0075] Melting a charge into molten steel in a vacuum induction smelting furnace, heating the charge until all the charge is melted, then filling argon into the smelting chamber until the pressure of the smelting chamber reaches 0.8×10.sup.4 Pa, stirring for 4 min, and regulating the temperature to 1540° C. and refining; during the primary refining, after refining 10 min each time, stirring for 4 min, and the primary refining lasts 40 min; sampling to analyze chemical components and inclusions in the molten steel, then replenishing argon into the smelting chamber until the pressure of the smelting chamber reaches 2.5×10.sup.4 Pa, adding electrolytic manganese, stirring for 4 min, then proceeding to the secondary refining which lasts 25 min; sampling and analyzing, removing the inclusions, stirring for 4 min, then regulating the temperature to 1600° C., and pouring the molten steel and casting to obtain the steel ingot.

[0076] (2) Electroslag Remelting

[0077] Forging the smelted steel ingot as a base material of a consumable electrode into a consumable electrode rod suitable for an electroslag remelting size of an electroslag furnace, removing a oxide skin from the surface of the consumable electrode rod, laying an arc initiating agent on a water jacket on the bottom of the electroslag furnace so that the consumable electrode rod, the arc initiating agent and the water jacket are in tight contact, baking the slag at a temperature of 600° C. and then starting the arc to form the slag, filling argon into the smelting chamber until the pressure of the smelting chamber reaches 2 MPa after completion of the slag formation, simultaneously adjusting the pressure of the cooling water in the electroslag crystallizer to 2 MPa, and then starting electroslag smelting; upon the electroslag smelting, the voltage is 38V, the electrical current is 9500 A, the temperature of the cooling water is 35° C., and the flow of the cooling water is 150 m.sup.3/h; feeding and then lifting the consumable electrode rod and ending the smelting; releasing the pressure, reducing the temperature and then getting out the remelted ingot.

[0078] The chemical components of the slag comprise in percentage by mass: CaO 6%, Al.sub.2O.sub.315%, SiO.sub.2 20%, MgO 5%, and the balance is CaF.sub.2. The melting speed of the electroslag smelting is 6.5 kg/min.

[0079] (3) Forging

[0080] A homogenization thermal process is performed for the remelted ingot, and then forging is performed to obtain a billet. The temperature at which the forging is started is 1140° C., and the temperature at which the forging is finished is 800° C.

[0081] (4) Steel Rolling

[0082] The forged billet is rolled at a temperature of 900° C. The rolling techniques including billet heating, hot rolling and Stelmor cooling control are employed to fabricate the wire rod for the ultra-thin ultra-high strength steel wire with a diameter of 5.5 mm. The chemical components of the wire rod for the ultra-thin ultra-high strength steel wire and information regarding the mass percentages of the chemical components are shown in Table 1.

[0083] The performances of the fabricated wire rod for the ultra-thin ultra-high strength steel wire are detected. The measured tensile strength, area reduction, sorbitic content and information of inclusions are shown in Table 2. The structure of the wire rod is mainly sorbite, and a small amount of pearlite. The metallographic structure is as shown in FIG. 1. The wire rod substantially does not have segregation of the structure. The wire rod is then subjected to deep processing, and drawn into the ultra-thin ultra-high strength steel wire. The wire rod is measured and the performances thereof are detected. The information of the ultra-thin ultra-high strength steel wire such as the diameter, tensile strength and drawing mileage i.e., the mileage of the wire without break when the wire rod is drawn into the steel wire are as shown in Table 3.

[0084] A Second Implementation

[0085] The second implementation differs from the first implementation in the remelting step, specifically as follows:

[0086] The remelting step comprises a vacuum consumable remelting step: taking the smelted steel ingot as a consumable electrode rod, placing the smelted steel ingot in the vacuum consumable remelting furnace, energizing and starting arc, then performing vacuum consumable crystallization and remelting to obtain the remelted ingot.

[0087] Preferably, the consumable electrode rod is subjected to vacuum consumable crystallization and then remelting under a degree of vacuum in a range of 0.01˜1 Pa.

[0088] Preferably, the voltage for energizing and starting arc is in a range of 20˜26V, and the length of the electric arc is in a range of 15˜20 mm.

[0089] Preferably, the melting speed in the vacuum consumable remelting is in a range of 3.5˜4.5 kg/min.

[0090] Except for the above difference, other steps of the second implementation and first implementation are all the same, and will not be detailed any more here.

[0091] Detailed description will be provided below through embodiments.

Embodiment 2

[0092] (1) Smelting

[0093] Melting a charge into molten steel in a vacuum induction smelting furnace, heating the charge until all the charge is melted, then filling argon into the smelting chamber until the pressure of the smelting chamber reaches 1.0×10.sup.4 Pa, stirring for 2 min, and regulating the temperature to 1545° C. for refining; during the primary refining, after refining 10 min each time, stirring for 3 min, and the primary refining lasts 25 min; sampling to analyze chemical components and inclusions in the molten steel, then replenishing argon into the smelting chamber until the pressure of the smelting chamber reaches 3×10.sup.4 Pa, adding electrolytic manganese, stirring for 3 min, then proceeding to the secondary refining which lasts 20 min; sampling and analyzing, removing the inclusions, stirring for 3 min, then regulating the temperature to 1605° C., and pouring the molten steel and casting to obtain the steel ingot.

[0094] (2) Vacuum Consumable Remelting

[0095] The smelted steel ingot is taken as the consumable electrode rod, the consumable electrode rod is placed in the vacuum consumable remelting furnace, the degree of vacuum in the vacuum consumable remelting furnace is controlled to 0.01 Pa, the voltage for energizing and starting arc is 20V, and the length of the electric arc is 20 mm. After energizing and starting the arc, vacuum consumable crystallization and remelting are performed at a melting speed of 4.5 kg/min to fabricate the remelted ingot.

[0096] (3) Forging

[0097] A homogenization thermal process is performed for the remelted ingot, and then forging is performed to obtain a billet. The temperature at which the forging is started is 1160° C., and the temperature at which the forging is finished is 900° C.

[0098] (4) Steel Rolling

[0099] The forged billet is rolled at a temperature of 1000° C. The rolling techniques including billet heating, hot rolling and Stelmor cooling control are employed to fabricate the wire rod for the ultra-thin ultra-high strength steel wire with a diameter of 5.5 mm. The chemical components of the wire rod for the ultra-thin ultra-high strength steel wire and information regarding the mass percentages of the chemical components are shown in Table 1.

[0100] The performances of the fabricated wire rod for the ultra-thin ultra-high strength steel wire are detected. The measured tensile strength, area reduction, sorbitic content and information of inclusions are shown in Table 2. The structure of the wire rod is mainly sorbite, and a small amount of pearlite. The metallographic structure is as shown in FIG. 2. The wire rod substantially does not have segregation of the structure. The wire rod is then subjected to deep processing, and drawn into the ultra-thin ultra-high strength steel wire. The wire rod is measured and the performances thereof are detected. The information of the ultra-thin ultra-high strength steel wire such as the diameter, tensile strength and drawing mileage (i.e., the mileage of the wire without break when the wire rod is drawn into the steel wire) are as shown in Table 3.

A Third Implementation

[0101] The third implementation differs from the first implementation in the remelting step, specifically as follows:

[0102] The remelting step comprises:

[0103] (1) An electroslag remelting step: forging the smelted steel ingot as a base material of a consumable electrode into a consumable electrode rod suitable for an electroslag remelting size of an electroslag furnace, removing a oxide skin from the surface of the consumable electrode rod, laying an arc initiating agent on a water jacket on the bottom of the electroslag furnace so that the consumable electrode rod, the arc initiating agent and the water jacket are in tight contact, baking the slag at a temperature in a range of 600˜800° C. and then starting arc to form the slag, filling argon into the smelting chamber to pressurize the smelting chamber, then starting electroslag smelting, feeding and then lifting the consumable electrode rod and ending the smelting, releasing the pressure, reducing the temperature and then getting out the remelted ingot.

[0104] Preferably, the electroslag remelting step comprises performing the following in order:

[0105] A slag-forming stage;

[0106] A pressure-controlling stage: controlling the pressure of the smelting furnace to a range of 2˜5 MPa, and making the pressure of cooling water in the crystallizer in a range of 2˜5 MPa;

[0107] An electroslag smelting stage: the voltage is in a range of 35˜38V, the electrical current is in a range of 8500˜9500 A, the temperature of the cooling water is in a range of 35˜40° C., and the flow of the cooling water is in a range of 130˜150 m.sup.3/h.

[0108] Preferably, the chemical components of the slag comprise in percentage by mass: CaO 6˜14%, Al.sub.2O.sub.38˜15%, SiO.sub.2 20˜28%, MgO <5%, and the balance is CaF.sub.2.

[0109] Further preferably, the chemical components of the slag comprise in percentage by mass: CaO 10%, Al.sub.2O.sub.310%, SiO.sub.2 25%, and the balance is CaF.sub.2.

[0110] Preferably, the melting speed in the electroslag remelting is in a range of 6.5˜7.5 kg/min.

[0111] (2) A Vacuum Consumable Remelting Step

[0112] The smelted ingot after the electroslag remelting is taken as the consumable electrode rod, and the consumable electrode rod is placed in the vacuum consumable remelting furnace. After energizing and starting the arc, vacuum consumable crystallization and remelting are performed to obtain the remelted ingot.

[0113] Preferably, the consumable electrode rod is subjected to vacuum consumable crystallization and then remelting under a degree of vacuum in a range of 0.01˜1 Pa.

[0114] Preferably, the voltage for energizing and starting arc is in a range of 20˜26V, and the length of the electric arc is in a range of 15˜20 mm.

[0115] Preferably, the melting speed in the vacuum consumable remelting is in a range of 3.5˜4.5 kg/min.

[0116] Except for the above difference, other steps of the third implementation and first implementation are all the same, and will not be detailed any more here.

[0117] Detailed description will be provided below through embodiments.

Embodiment 3

[0118] (1) Smelting

[0119] Melting a charge into molten steel in a vacuum induction smelting furnace, heating the charge until all the charge is melted, then filling argon into the smelting chamber until the pressure of the smelting chamber reaches 0.9×10.sup.4 Pa, stirring for 3 min, and regulating the temperature to 1535° C. for refining; during the primary refining, after refining 10 min each time, stirring for 2 min, and the primary refining lasts 32 min; sampling to analyze chemical components and inclusions in the molten steel, then replenishing argon into the smelting chamber until the pressure of the smelting chamber reaches 2.8×10.sup.4 Pa, adding electrolytic manganese, stirring for 2 min, then proceeding to the secondary refining which lasts 15 min; sampling and analyzing, removing the inclusions, stirring for 2 min, then regulating the temperature to 1595° C., and pouring the molten steel and casting to obtain the steel ingot.

[0120] (2) Electroslag Remelting

[0121] Forging the smelted steel ingot as a base material of a consumable electrode into a consumable electrode rod suitable for an electroslag remelting size of an electroslag furnace, removing a oxide skin from the surface of the consumable electrode rod, laying an arc initiating agent on a water jacket on the bottom of the electroslag furnace so that the consumable electrode rod, the arc initiating agent and the water jacket are in tight contact, baking the slag at a temperature of 800° C. and then starting the arc to form the slag, filling argon into the smelting chamber until the pressure of the smelting chamber reaches 5 MPa after completion of the slag formation, simultaneously adjusting the pressure of the cooling water in the electroslag crystallizer to 5 MPa, and then starting electroslag smelting; upon the electroslag smelting, the voltage is 35V, the electrical current is 8500 A, the temperature of the cooling water is 40° C., and the flow of the cooling water is 130 m.sup.3/h; feeding and then lifting the consumable electrode rod and ending the smelting; releasing the pressure, reducing the temperature and then getting out the remelted ingot.

[0122] The chemical components of the slag comprise in percentage by mass: CaO 14%, Al.sub.2O.sub.3 8%, SiO.sub.2 28%, MgO 3%, and the balance is CaF.sub.2. The melting speed of the electroslag smelting is 7.5 kg/min.

[0123] (3) Vacuum Consumable Remelting

[0124] The remelted ingot after the electroslag remelting is taken as the consumable electrode rod, the consumable electrode rod is placed in the vacuum consumable remelting furnace, the degree of vacuum in the vacuum consumable remelting furnace is controlled to 1 Pa, the voltage for energizing and starting arc is 26V, and the length of the electric arc is 15 mm. After energizing and starting the arc, vacuum consumable crystallization and remelting are performed at a melting speed of 3.5 kg/min to fabricate the steel ingot.

[0125] (4) Forging

[0126] A homogenization thermal process is performed for the steel ingot after the vacuum consumable remelting, and then forging is performed to obtain a billet. The temperature at which the forging is started is 1150° C., and the temperature at which the forging is finished is 850° C.

[0127] (5) Steel Rolling

[0128] The forged billet is rolled at a temperature of 1100° C. The rolling techniques including billet heating, hot rolling and Stelmor cooling control are employed to fabricate the wire rod for the ultra-thin ultra-high strength steel wire with a diameter of 5.5 mm. The chemical components of the wire rod for the ultra-thin ultra-high strength steel wire and information regarding the mass percentages of the chemical components are shown in Table 1.

[0129] The performances of the fabricated wire rod for the ultra-thin ultra-high strength steel wire are detected. The measured tensile strength, area reduction, sorbitic content and information of inclusions are shown in Table 2. The structure of the wire rod is mainly sorbite, and a small amount of pearlite. The metallographic structure is as shown in FIG. 3. The wire rod substantially does not have segregation of the structure. The wire rod is then subjected to deep processing, and drawn into the ultra-thin ultra-high strength steel wire. The wire rod is measured and the performances thereof are detected. The information of the ultra-thin ultra-high strength steel wire such as the diameter, tensile strength and drawing mileage (i.e., the mileage of the wire without break when the wire rod is drawn into the steel wire) are as shown in Table 3.

TABLE-US-00001 TABLE 1 Chemical components, Embodi- Embodi- Embodi- wt % ment 1 ment 2 ment 3 C 0.90 0.92 0.94 Si 0.30 0.20 0.12 Mn 0.65 0.45 0.30 Cr 0.10 0.20 0.30 Al 0.004 0.003 0.002 Ti 0.0007 0.0005 0.001 Cu 0.01 0.005 0.006 Ni 0.01 0.006 0.008 S 0.01 0.002 0.0018 P 0.01 0.005 0.0044 O 0.0006 0.00044 0.0004 N 0.0006 0.0006 0.00055 Fe and Balance Balance Balance unavoidable impurity elements

TABLE-US-00002 TABLE 2 Embodi- Embodi- Embodi- Embodiments ment 1 ment 2 ment 3 Tensile strength, Head 1320.50 1336.27 1350.35 MPa Tail 1305.50 1324.40 1332.28 Area reduction, % Head 42.75 41.88 41.22 Tail 41.24 40.26 40.10 Sorbitic content, % 95 96 97 Average density of brittle 2 1 1 inclusions, /mm.sup.2 Maximum size of the 4 3 3 inclusion, μm

TABLE-US-00003 TABLE 3 Embodi- Embodi- Embodi- Embodiments ment 1 ment 2 ment 3 Diameter, μm 60 55 50 Tensile strength, MPa 4512 4608 4720 Drawing mileage, km ≥300 ≥300 ≥300

[0130] To conclude, as compared with the prior art, the present invention has the following advantageous effects:

[0131] (1) The size, strength and purity of the wire rod for the ultra-thin ultra-high strength steel wire are controlled by controlling the chemical components and mass percentages, wherein the structure and strength of the wire rod for the ultra-thin ultra-high strength steel wire are controlled by controlling content of elements such as C, Si, Mn and Cr and carbon-free segregation in the wire rod; the amount of inclusions is controlled by controlling the content of elements such as Al, Ti, O and N that generate brittle inclusions; in the finally-fabricated wire rod for ultra-thin ultra-high strength steel wire, the content of full oxygen is less than or equal to 0.0006%, the content of N is less than or equal to 0.0006%, the size of the inclusions is less than or equal to 4 μm, and the average density of the brittle inclusions is less than or equal to 2 inclusions/mm.sup.2. The wire rod for the ultra-thin ultra-high strength steel wire with a diameter of 5.5 mm has a sorbite rate larger than or equal to 95%, an area reduction rate larger than or equal to 40%, and a tensile strength larger than or equal to 1300 MPa. The purity of the wire rod is substantially improved, and the wire rod has excellent strength, toughness and drawing performance. The wire rod facilitates fabricating a drawn steel wire with a higher purity, a smaller diameter and a longer mileage of the continuous wire without break.

[0132] (2) On one hand, through operations such as the smelting and remelting, precise control of chemical components of the wire rod for the ultra-thin ultra-high strength steel wire is achieved, and the strength and the drawing performance thereof are improved; on the other hand, it is possible to, by remelting, control the components and crystallization directions of the inclusions, remove the inclusions to a larger degree, reduce the sizes of the inclusions, improve the purity of the wire rod, and further control the wire rod free from central segregation. The structure of the wire rod is more uniform and compact, the steel ingots do not have solidification drawbacks such as shrinkage cavity, porosity and segregation, and the plasticity and toughness of the steel ingots at a low temperature, a room temperature and a high temperature are enhanced, so that the chemical components and inclusions of the finally-fabricated wire rod for the ultra-thin ultra-high strength steel wire are effectively and precisely controlled, and the wire rod is ensured to have a high strength, an excellent drawing performance and a high purity, and it is further ensured that the ultra-thin ultra-high strength steel wire fabricated by drawing from the wire rod has an ultra-small diameter, an ultra-high tensile strength, a super-long mileage of continuous wire without break and an ultra-high purity.