High-strength cableway rope wire rod and preparation method thereof

Abstract

The invention discloses a high-strength cableway rope wire rod and a preparation method thereof. The high-strength cableway rope wire rod comprises the following components in percentage by mass: 0.80%-0.84% of C, 0.15%-0.25% of Si, 0.50%-0.60% of Mn, less than or equal to 0.015% of P, 0.0030%-0.010% of S, 0.0010%-0.0030% of total oxygen, 0.0005%-0.0015% of Als, 0.0002%-0.0010% of V, 0.0002%-0.0011% of Co, 0.0001%-0.0012% of Mg and the balance of iron and inevitable impurities. Through the design of the chemical components and the production process of the wire rod, the thickness difference of cementite lamellas on the surface and the core of the wire rod is smaller than or equal to 0.03 mu m, and the quality requirement and the operation quality requirement of the high-strength cableway rope are met.

Description

Technical Field

[0001] The invention relates to the technical field of materials and metallurgy, and more specifically, to a high-strength cableway rope coil and a preparation method thereof. Background Art

[0002] Ropeway rope is a kind of steel wire rope with extremely high safety performance requirements. Ropeway rope is subjected to repeated stretching, impact and friction during service. In order to ensure the safety performance of ropeway rope, the wire rod needs to have high deformation performance to meet the production and service performance requirements of ropeway rope. High-strength wire rod for ropeway rope is widely used in important equipment, and the wire rod structure needs to be precisely controlled to meet the quality requirements of users for high-strength ropeway rope.

[0003] The Chinese invention patent with publication number CN102268596B discloses a high carbon steel wire rod for producing fine steel wire, the chemical composition weight percentage of the wire rod is: [C]: 0.6% to 0.88%, [Si]: 0.1% to 1.0%, [Mn]: 0.3% to 1.0%, [P] ≤ 0.015%, [S] ≤ 0.010%, [N] ≤ 0.004%, [O] ≤ 0.002%, [Al] ≤ 0.002%, [Ti] ≤ 0.002%, [Mg] ≤ 0.001%, other unavoidable impurities are not higher than 0.1%, and the rest is iron. The patent application focuses on optimizing the production process of high carbon steel wire rod, and does not carry out the wire rod composition design and production process design from the perspective of organizational control.

[0004] As the equipment manufacturing industry's requirements for the quality of high-strength ropeways continue to increase, research on how to accurately control the wire rod structure to meet the quality requirements of high-strength ropeway rope production and operation has become an important topic that needs to be studied urgently. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and to provide a high-strength cableway rope wire rod and a preparation method thereof. Through the chemical composition of the wire rod and the production process design, the difference in cementite lamella thickness between the surface and the core of the wire rod is made ≤0.03μm, thereby meeting the quality requirements for the production and operation of high-strength cableway ropes.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A high-strength cableway rope wire rod comprises the following components in percentage by mass: C: 0.80%-0.84%, Si: 0.15%-0.25%, Mn: 0.50%-0.60%, P≤0.015%, S: 0.0030%-0.010%, total oxygen: 0.0010%-0.0030%, Als: 0.0005-0.0015%, V: 0.0002%-0.0010%, Co: 0.0002%-0.0011%, Mg: 0.0001%-0.0012%, and the balance is iron and unavoidable impurities.

[0008] The present invention also discloses a method for preparing the high-strength cableway rope wire rod as described above, comprising the following steps: converter smelting, LF refining, continuous casting, continuous casting billet heating and continuous rolling, wire rod rolling, and wire rod cooling;

[0009] During the continuous casting billet heating and continuous rolling, the continuous casting billet off the line in the continuous casting process is sent to a heating furnace for heating, and the total time in the furnace is 2.0h to 3.5h; the temperature of the soaking section is 1200°C to 1220°C, and the holding time is 60min to 80min; after the continuous casting billet is heated, continuous rolling is performed, and the final rolling temperature is 880°C to 920°C;

[0010] In the wire rod rolling, the steel billet after continuous rolling is heated in a heating furnace, and then subjected to rough rolling, intermediate rolling, pre-finishing rolling, finishing rolling, and wire laying in sequence;

[0011] During the wire rod cooling, the wire rod is cooled on an air-cooled roller after spinning.

[0012] Implementing the embodiments of the present invention will have the following beneficial effects:

[0013] The present invention adopts reasonable component design and "converter smelting, LF refining, continuous casting, continuous casting billet heating and continuous rolling, wire rod rolling, wire rod cooling" process. The high-strength rope wire rod produced by the production method provided by the present invention has a tensile strength of 1020MPa-1150MPa, a cementite layer thickness at the surface of the wire rod of 0.01μm-0.04μm, and a cementite layer thickness at a distance of 1 / 4 of the diameter from the surface of 0.02μm-0.05μm, so that the difference in cementite layer thickness between the surface and the core of the produced high-strength rope wire rod is no more than 0.03μm, which meets the requirements of uniform deformation of the wire rod and the surface and the core of the steel wire in the production process of the high-strength rope wire, enhances the uniformity of the structure of the cross section of the steel wire, and prolongs the service life of the steel wire rope.

[0014] At the same time, the preparation method of the present invention has the characteristics of low production cost, strong process applicability, etc., which is conducive to its production and promotion and application, and has significant social benefits. DETAILED DESCRIPTION

[0015] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0016] 1. Chemical composition and mechanical properties

[0017] The invention discloses a high-strength cableway rope coil, comprising the following components in percentage by mass:

[0018] C: 0.80%~0.84%, Si: 0.15%~0.25%, Mn: 0.50%~0.60%, P≤0.015%, S: 0.0030%~0.010%, total oxygen: 0.0010%~0.0030%, Als: 0.0005~0.0015%, V: 0.0002%~0.0010%, Co: 0.0002%~0.0011%, Mg: 0.0001%~0.0012%, and the balance is iron and inevitable impurities.

[0019] Specifically, the mechanism of action of each alloy component in the wire rod of the present invention is as follows:

[0020] Too high a carbon content in the wire rod will cause the ropeway rope made from the wire rod to exceed the strength requirement range; at the same time, a higher strength will increase the wire breakage rate of the wire rod in the process of preparing the ropeway rope, and increase the scrap rate of the user. Too low a carbon content in the wire rod cannot meet the user's requirements for the strength of the wire rope. Therefore, the carbon content in the present invention is controlled at 0.80% to 0.84%.

[0021] Silicon increases the eutectoid transformation temperature of steel and makes the pearlite structure of the wire rod coarse, which is not conducive to the complex deformation of the ropeway rope processing process. Silicon is the main deoxidizing element in high carbon steel. If the silicon content in the steel is too high, coarse silicates and impurities will appear after the molten steel is deoxidized. If the silicon content is low, the molten steel will be insufficiently deoxidized, thereby reducing the deformation ability of the wire rod in the process of processing special-shaped steel wire. Therefore, the silicon content in the present invention is controlled at 0.15% to 0.25%.

[0022] Manganese is an element that improves the strength of wire rods, which is beneficial to ensure that the steel wire rope processed by wire rods meets the tensile strength requirements of users; manganese has the effect of reducing the eutectoid transformation temperature of steel, refining the pearlite structure of wire rods, and improving the deformation ability of wire rods in the process of processing ropeway rope steel wires. Therefore, the manganese content in the present invention is controlled at 0.50% to 0.60%.

[0023] Phosphorus reduces the deformation capacity of the wire rod in the ropeway rope processing, causing the steel wire to crack and break, so the phosphorus content in the present invention is controlled to be ≤0.015%.

[0024] A higher sulfur content in the steel reduces the cold working performance of the wire rod. Since MnS inclusions have good deformation ability, a proper amount of sulfur in the steel can reduce the harm of spar inclusions, so the sulfur content in the present invention is controlled at 0.0030% to 0.010%.

[0025] When the oxygen content is low, the inclusions in the wire rod have poor deformation ability, which is not conducive to the processing of the ropeway rope; when the oxygen content in the wire rod is high, the inclusions in the steel are large in size and large in number, which easily leads to cracking and breaking of the ropeway rope during processing. Therefore, the total oxygen content of the wire rod in the present invention is controlled at 0.0010% to 0.0030%.

[0026] When the acid-soluble aluminum content is high, larger Al2O3 inclusions will appear in the steel; when the acid-soluble aluminum content in the wire rod is too low, the inclusions in the steel have a high melting point, and cracks are likely to occur between the inclusions and the matrix during processing, resulting in cracking and breaking of the ropeway rope during processing. Therefore, the acid-soluble aluminum content of the present invention is controlled to be 0.0005% to 0.0015%.

[0027] The vanadium element is dissolved in the steel to improve the strength of the steel. However, the vanadium content in the steel should not be too high to prevent the higher wire rod strength from reducing the drawing performance of the wire rod. The vanadium element can inhibit the growth of the grains of the steel billet when the billet is heated, thereby refining the pearlite structure of the wire rod, which is beneficial to improving the uniform deformation ability of the wire rod during the ropeway rope processing process. Therefore, the vanadium content in the present invention is controlled at 0.0002% to 0.0010%.

[0028] Cobalt element is dissolved in steel to improve the strength of steel. However, the cobalt content in steel should not be too high to prevent the higher wire rod strength from reducing the drawing performance of the wire rod. Cobalt element increases the precipitation temperature of proeutectoid ferrite, increases the transformation temperature of austenite to pearlite, inhibits the appearance of Widmanstätten structure in the wire rod, reduces the content of troostite in the wire rod, and improves the uniform deformation performance of the wire rod. Therefore, the cobalt content in the present invention is controlled at 0.0002% to 0.0011%.

[0029] The magnesium element controls the oxygen content in the steel and also controls the type of inclusions in the steel. A higher magnesium content causes magnesium-aluminum spinel inclusions to appear in the steel, which reduces the processing performance of the wire rod. An appropriate amount of magnesium content in the steel improves the deformation performance of the inclusions, expands the area with higher deformation of the inclusions, and is conducive to improving the coordinated deformation ability of the wire rod. Therefore, the magnesium content of the present invention is controlled at 0.0001% to 0.0012%.

[0030] In a specific embodiment, the tensile strength of the wire rod of the present invention is 1020 MPa to 1150 MPa.

[0031] In a specific embodiment, the cementite lamella thickness at the surface of the wire rod of the present invention is 0.01μm to 0.04μm, the cementite lamella thickness at 1 / 4 diameter from the surface is 0.02μm to 0.05μm, and the cementite lamella thickness at the core is 0.03μm to 0.06μm.

[0032] 2. Production technology

[0033] The present invention also discloses a method for preparing a high-strength wire rod for a cableway rope as in any embodiment of the present invention, comprising the following steps: converter smelting, LF refining, continuous casting, continuous casting billet heating and continuous rolling, wire rod rolling, and wire rod cooling.

[0034] Further, the method specifically includes the following steps:

[0035] S1. In converter smelting, scrap steel and molten iron are used as furnace charge, and the mass percentage of scrap steel in the furnace charge is 3% to 10%; the oxygen activity of the molten steel after converter smelting is controlled at 130ppm to 150ppm.

[0036] In S2 and LF refining, the molten steel discharged from the converter is put into the LF furnace for refining. The refining temperature of the LF furnace is 1430°C to 1520°C, and the refining time is 25min to 60min.

[0037] S3. During continuous casting, the molten steel subjected to LF refining treatment is continuously cast to obtain a continuously cast ingot.

[0038] In a specific embodiment, the cross-sectional size of the continuous casting billet is (260 mm to 300 mm)*(260 mm to 300 mm). The thickness of the immersion nozzle sealing gasket during the continuous casting process is 10 mm to 16 mm.

[0039] S4. During the continuous casting billet heating and continuous rolling, the continuous casting billet off the line in the continuous casting process is sent to the heating furnace for heating, and the total time in the furnace is 2.0h to 3.5h; the temperature of the soaking section is 1200℃ to 1220℃, and the insulation time is 60min to 80min; after the continuous casting billet is heated, it is continuously rolled, and the final rolling temperature is 880℃ to 920℃.

[0040] In a specific embodiment, the cross-sectional size of the continuous rolling billet is (140mm-180mm)×(140mm-180mm); the size of inclusions in the core of the continuous rolling billet is ≤32μm, the size of inclusions at a position 1 / 4 of the thickness of the continuous rolling billet from the surface is ≤28μm, and the size of inclusions at the surface of the continuous rolling billet is ≤20μm. The mass percentage of Al2O3 in the inclusions is ≤30%, the mass percentage of MgO is ≤15%, and the mass percentage of FeO is ≤5%; the banded structure of the continuous rolling billet is ≤1 level.

[0041] S5. During the wire rod rolling, the steel billet after continuous rolling is heated in a heating furnace, and then sequentially subjected to rough rolling, intermediate rolling, pre-finishing rolling, finishing rolling, and wire drawing.

[0042] In a specific embodiment, in the wire rod rolling, the wire rod is produced by a square billet, the total furnace time of the billet is 100min-140min, the temperature of the soaking section is 1080℃-1110℃, and the insulation time of the billet soaking section is 30min-50min; the billet heating process is in the austenite high temperature zone, and the carbon content at the interface of austenite and cementite is 1.25%-1.4%; after the billet is heated, it is subjected to rough rolling, intermediate rolling, pre-finishing rolling and finishing rolling, and then the wire rod spinning operation is carried out; the pre-finishing rolling temperature of the wire rod is 900℃-925℃; the finishing rolling temperature is 890℃-910℃; the temperature of the double module is 870℃-890℃; the wire rod spinning temperature is 850℃-870℃. The wire rod rolling specification is 8mm-12mm.

[0043] S6. During the cooling of the wire rod, the wire rod is cooled on an air-cooled roller after spinning to obtain high-quality wire rod for hose steel wire.

[0044] In a specific embodiment, during the cooling of the wire rod, the wire rod is cooled on an air-cooled roller after spinning, the cementite precipitation temperature of the wire rod is controlled to be 620°C ~ 670°C, the phase change temperature of the wire rod on the air-cooling line is controlled to be 650°C ~ 680°C, the phase change time is 15s ~ 25s, and the cooling rate of the phase change process is 2°C / s ~ 6°C / s.

[0045] The following are specific embodiments

[0046] Examples 1-6

[0047] The chemical composition, preparation process and performance parameters of the wire rods of Examples 1-6 of the present invention are shown in Table 1.

[0048] Table 1 Chemical composition, preparation process and performance parameters of wire rods of Examples 1-6

[0049]

[0050]

[0051] According to the above results, the present invention has carried out a large number of systematic experimental studies from the aspects of alloy element screening and proportioning, as well as converter smelting, LF refining, continuous casting, continuous casting billet heating and continuous rolling, wire rod rolling, and wire rod cooling process design optimization, and finally determined the component system and its manufacturing process that can meet the purpose of the present invention, and finally obtained a high-strength cableway rope wire rod with a difference in cementite lamella thickness between the surface and the core of the wire rod of no more than 0.03μm.

[0052] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A high-strength cableway rope wire rod, characterized in that: The wire rod includes the following components in mass percentage: C: 0.80%~0.84%, Si: 0.15%~0.25%, Mn: 0.50%~0.60%, P≤0.015%, S: 0.0030%~0.010%, total oxygen: 0.0010%~0.0030%, Als: 0.0005~0.0015%, V: 0.0002%~0.0010%, Co: 0.0002%~0.0011%, Mg: 0.0001%~0.0012%, and the balance is iron and inevitable impurities.

2. The high-strength cableway rope coil according to claim 1, characterized in that: The tensile strength of the wire rod is 1020MPa to 1150MPa.

3. The high-strength cableway rope coil according to claim 1, characterized in that: The thickness of the cementite lamellae at the surface of the wire rod is 0.01μm to 0.04μm, the thickness of the cementite lamellae at 1 / 4 diameter from the surface is 0.02μm to 0.05μm, and the thickness of the cementite lamellae at the core is 0.03μm to 0.06μm.

4. A method for preparing a high-strength cableway rope wire rod as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: Converter smelting, LF refining, continuous casting, continuous casting billet heating and rolling, wire rod rolling, wire rod cooling; During the continuous casting billet heating and continuous rolling, the continuous casting billet off the line in the continuous casting process is sent to a heating furnace for heating, and the total time in the furnace is 2.0h to 3.5h; the temperature of the soaking section is 1200°C to 1220°C, and the holding time is 60min to 80min; after the continuous casting billet is heated, continuous rolling is performed, and the final rolling temperature is 880°C to 920°C; In the wire rod rolling, the steel billet after continuous rolling is heated in a heating furnace, and then subjected to rough rolling, intermediate rolling, pre-finishing rolling, finishing rolling, and wire laying in sequence; During the wire rod cooling, the wire rod is cooled on an air-cooled roller after spinning.

5. The preparation method according to claim 4, characterized in that: In the converter smelting, scrap steel and molten iron are used as furnace charge, and the mass percentage of scrap steel in the furnace charge is 3% to 10%; the oxygen activity of the molten steel after converter smelting is controlled at 130ppm to 150ppm.

6. The preparation method according to claim 4, characterized in that: In the LF refining, the molten steel discharged from the converter smelting enters the LF furnace for refining treatment. The refining temperature of the LF furnace is 1430° C. to 1520° C., and the refining time is 25 min to 60 min.

7. The preparation method according to claim 4, characterized in that: In the continuous casting, the cross-sectional size of the continuous casting billet is (260mm-300mm)*(260mm-300mm); the thickness of the immersed water inlet sealing gasket in the continuous casting process is 10mm-16mm.

8. The preparation method according to claim 4, characterized in that: During the heating and continuous rolling of the continuous casting billet, the cross-sectional size of the continuous rolling billet is (140mm~180mm)×(140mm~180mm); the size of inclusions in the core of the continuous rolling billet is ≤32μm, the size of inclusions at a position 1 / 4 of the thickness from the surface of the continuous rolling billet is ≤28μm, and the size of inclusions at the surface of the continuous rolling billet is ≤20μm; the mass percentage of Al2O3 in the inclusions is ≤30%, the mass percentage of MgO is ≤15%, and the mass percentage of FeO is ≤5%; the banded structure of the continuous rolling billet is ≤level 1.

9. The preparation method according to claim 4, characterized in that: In the wire rod rolling, the total furnace time of the steel billet is 100min-140min, the temperature of the soaking section is 1080℃-1110℃, and the insulation time of the steel billet soaking section is 30min-50min; the steel billet heating process is in the austenite high temperature zone, and the carbon content at the interface of austenite and cementite is 1.25%-1.4%; after the steel billet is heated, it is subjected to rough rolling, intermediate rolling, pre-finishing rolling and finishing rolling, and then the wire rod spinning operation is carried out; the pre-finishing rolling temperature of the wire rod is 900℃-925℃; The temperature entering the finishing rolling is 890℃~910℃; the temperature entering the double module is 870℃~890℃; the wire rod spinning temperature is 850℃~870℃.

10. The preparation method according to claim 4, characterized in that: During the wire rod cooling, the wire rod is cooled on an air-cooled roller after spinning, the cementite precipitation temperature of the wire rod is controlled to be 620°C to 670°C, the phase change temperature of the wire rod on the air-cooled line is 650°C to 680°C, the phase change time is 15s to 25s, and the cooling rate of the phase change process is 2°C / s to 6°C / s.

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