Wire rod for ultrahigh-strength cableway rope and preparation method of wire rod

Abstract

The invention discloses a wire rod for an ultrahigh-strength cableway rope and a preparation method of the wire rod. The wire rod comprises the following components in percentage by mass: 0.90%-0.94% of C, 0.12%-0.27% of Si, 0.15%-0.30% 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, 0.0001%-0.0010% of Nb, 0.0003%-0.0010% of Co, 0.0002%-0.0010% of Mg and the balance of iron and inevitable impurities. A reasonable component design and an optimal production process are adopted, so that the thickness difference of ferrite sheets on the surface and the core part of the produced wire rod for the ultrahigh-strength cableway rope is not greater than 0.05 mu m, and the quality requirements of production and operation of the cableway rope are met.

Description

Technical Field

[0001] The present invention relates to the technical field of materials and metallurgy, and more specifically, to a wire rod for ultra-high strength cableway ropes and a preparation method thereof. Background Art

[0002] The ropeway rope is subjected to repeated stretching, impact and friction during service, so the ropeway rope is a kind of steel wire rope with extremely high safety performance requirements. In order to ensure the safety performance of the ropeway rope, the wire rod needs to have high deformation performance to meet the production and service performance requirements of the ropeway rope. The wire rod for ultra-high strength ropeway rope with a strength level of 1200MPa is more prone to fatigue failure during service due to its high strength. It is necessary to accurately control the wire rod structure to meet the quality requirements of users for ultra-high strength ropeway ropes.

[0003] The Chinese patent application with application number 202310976619.5 provides a wire rod for ultra-high strength hot-dip galvanized steel wire rope and a production method thereof, wherein the chemical composition by mass percentage is: C: 0.85-0.88%, Si: 0.18-0.25%, Mn: 0.50-0.55%, Cr: ≤0.05%, P≤0.012%, S≤0.008%, Ni≤0.05%, Cu≤0.05%, Mo≤0.03%, Al≤0.0020%, Ti≤0.0012%, O≤0.0030%, N≤0.0050%, and the balance is Fe and unavoidable impurities. During production, the process of molten steel smelting, LF refining, continuous casting and steel rolling can produce ultra-high strength hot-dip galvanized steel wire rope wire rod, which can improve the strength of the wire rod while solving the problems of segregation in the core of the wire rod, insufficient content of network cementite and troostite. This patent discloses ultra-high strength hot-dip galvanized steel wire rope wire rod, but does not design the wire rod composition and production process from the perspective of organizational control.

[0004] As the equipment manufacturing industry's quality requirements for ultra-strength ropes continue to increase, research on how to accurately control the wire rod structure to meet the quality requirements of ultra-high-strength 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 wire rod for ultra-high strength ropeway rope and a preparation method thereof, so that the produced wire rod for ultra-high strength ropeway rope can meet the quality requirements of ropeway rope production and operation through the chemical composition of the wire rod and the production process design.

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

[0007] A wire rod for ultra-high strength cableway ropes, comprising the following components in percentage by mass:

[0008] C: 0.90%~0.94%, Si: 0.12%~0.27%, Mn: 0.15%~0.30%, P≤0.015%, S: 0.0030%~0.010%, total oxygen: 0.0010%~0.0030%, Als: 0.0005%~0.0015%, Nb: 0.0001%~0.0010%, Co: 0.0003%~0.0010%, Mg: 0.0002%~0.0010%, and the balance is iron and unavoidable impurities.

[0009] The present invention also discloses a method for preparing the ultra-high strength wire rod for cableway ropes 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;

[0010] 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 furnace time is 3.6h to 4.1h; the soaking section temperature is 1180°C to 1210°C, and the holding time is 45min to 55min; after the continuous casting billet is heated, continuous rolling is performed, and the final rolling temperature is 930°C to 980°C;

[0011] 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;

[0012] During the cooling of the wire rod, the wire rod is cooled on an air-cooled roller after spinning to obtain the wire rod for the ultra-high strength cableway rope.

[0013] Implementing the embodiments of the present invention will have the following beneficial effects:

[0014] The present invention adopts reasonable component design and "converter smelting, LF refining, continuous casting smelting process smelting and rolling" process, so that the difference in ferrite layer thickness between the surface and the core of the produced ultra-high strength ropeway wire rod is no more than 0.05μm, meeting the quality requirements of no wire breakage during the drawing and stranding process of the ropeway production process, and no elongation of the wire rope during the operation process. At the same time, the preparation method of the present invention has the characteristics of low production cost and strong process applicability, 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 wire rod for an ultra-high strength ropeway, comprising the following components in mass percentage: C: 0.90%-0.94%, Si: 0.12%-0.27%, Mn: 0.15%-0.30%, P≤0.015%, S: 0.0030%-0.010%, total oxygen: 0.0010%-0.0030%, Als: 0.0005%-0.0015%, Nb: 0.0001%-0.0010%, Co: 0.0003%-0.0010%, Mg: 0.0002%-0.0010%, and the balance is iron and inevitable impurities.

[0018] Specifically, the mechanism of action of each alloy component in the wire rod of the present invention is as follows:

[0019] 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 0.90% to 0.94%.

[0020] 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 0.12% to 0.27%.

[0021] 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 user's tensile strength requirements; 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 0.15% to 0.30%.

[0022] 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%.

[0023] 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%.

[0024] 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%.

[0025] 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%.

[0026] Niobium can refine the pearlite structure of the wire rod by inhibiting the grain growth of the steel billet during the heating process, thereby improving the deformation capacity of the wire rod during the ropeway rope processing process. However, a higher niobium content leads to a higher niobium carbonitride content in the steel, and the wire rod is severely hardened during the steel wire processing process, which is easy to cause cracking and breaking of the steel wire. Therefore, the niobium content of the present invention is controlled at 0.0001% to 0.0010%.

[0027] 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 0.0003% to 0.0010%.

[0028] 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 0.0002% to 0.0010%.

[0029] In a specific embodiment, the tensile strength of the wire rod of the present invention is 1170 MPa to 1270 MPa.

[0030] In a specific embodiment, the ferrite lamella thickness at the surface of the wire rod of the present invention is 0.04μm to 0.06μm, the ferrite lamella thickness at 1 / 4 diameter from the surface is 0.06μm to 0.08μm, and the ferrite lamella thickness at the core is 0.08μm to 0.10μm.

[0031] 2. Production technology

[0032] The present invention also discloses a method for preparing a wire rod for ultra-high strength ropeway 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.

[0033] Further, the method specifically includes the following steps:

[0034] 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 2% to 13%; the oxygen activity of the molten steel after converter smelting is controlled at 160ppm to 200ppm.

[0035] 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 1410°C to 1490°C, and the refining time is 30min to 50min.

[0036] S3. During continuous casting, the molten steel subjected to LF refining treatment is continuously cast to obtain a continuously cast ingot.

[0037] In a specific embodiment, the cross-sectional size of the continuous casting billet is (260mm-300mm)×(360mm-400mm); the casting speed during the continuous casting process is 0.60m / min-0.80m / min, and the superheat degree of the molten steel in the tundish is 10°C-30°C.

[0038] 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 3.6h~4.1h; the temperature of the soaking section is 1180℃~1210℃, and the insulation time is 45min~55min; after the continuous casting billet is heated, it is continuously rolled, and the final rolling temperature is 930℃~980℃.

[0039] In a specific embodiment, the cross-sectional size of the continuous rolling billet is (140mm-180mm)×(140mm-180mm); the size of the inclusions in the core of the continuous rolling billet is ≤30μm, the size of the inclusions at a position 1 / 4 of the thickness of the continuous rolling billet from the surface is ≤25μm, and the size of the inclusions at the surface of the continuous rolling billet is ≤23μm. The mass percentage of Al2O3 in the inclusions is 5%-30%, the mass percentage of MgO is 5%-15%, and the mass percentage of FeO is 1%-5%. The FeO content of the iron oxide scale on the surface of the continuous rolling billet is 50%-70%.

[0040] 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.

[0041] In a specific embodiment, during the wire rod rolling, the wire rod is produced by a square billet, the total furnace time of the billet is 150min-160min, the temperature of the soaking section is 1100℃-1140℃, and the insulation time of the billet soaking section is 40min-80min; after the billet is heated, the surface iron oxide FeO mass percentage is ≥60%, and the Fe2O3 mass percentage is ≤10%. After rough rolling, intermediate rolling, pre-finishing rolling and finishing rolling, the wire rod spinning operation is carried out; the pre-finishing rolling temperature of the wire rod is 980℃-995℃; the finishing rolling temperature is 850℃-930℃; the temperature of the double module is 910℃-940℃; the wire rod spinning temperature is 910℃-940℃. The wire rod rolling specification is 8mm-12mm.

[0042] S6. During the cooling of the wire rod, the wire rod is cooled on an air-cooled roller after spinning to obtain a wire rod for ultra-high strength cableway ropes.

[0043] In a specific embodiment, during the cooling of the wire rod, the wire rod is cooled on an air-cooled roller after spinning, and the phase change temperature of the wire rod is controlled to be 620°C ~ 670°C, and the phase change time of the wire rod on the air-cooled line is 15 to 25s; after the temperature of the wire rod on the air-cooled roller is less than 600°C, the cooling rate is 5°C / s ~ 10°C / s, and the wire rod coiling temperature is 180°C ~ 300°C.

[0044] The following are specific embodiments

[0045] Examples 1-6

[0046] 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.

[0047] Table 1 Chemical composition, preparation process and performance parameters of wire rods of Examples 1-6

[0048]

[0049]

[0050] 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, converter smelting, LF refining, continuous casting, continuous casting billet heating and continuous rolling, wire rod rolling, wire rod cooling process design optimization, etc., and finally determined the component system and its manufacturing process that can meet the purpose of the present invention, and finally obtained an ultra-high strength cableway rope wire rod with a ferrite lamellar spacing difference of no more than 0.05μm between the surface and the core of the wire rod.

[0051] 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 wire rod for ultra-high strength cableway rope, characterized in that: The following components are included in mass percentage: C: 0.90%~0.94%, Si: 0.12%~0.27%, Mn: 0.15%~0.30%, P≤0.015%, S: 0.0030%~0.010%, total oxygen: 0.0010%~0.0030%, Als: 0.0005%~0.0015%, Nb: 0.0001%~0.0010%, Co: 0.0003%~0.0010%, Mg: 0.0002%~0.0010%, and the balance is iron and unavoidable impurities.

2. The wire rod for ultra-high strength ropeway rope according to claim 1, characterized in that: The tensile strength of the wire rod is 1170MPa to 1270MPa.

3. The wire rod for ultra-high strength ropeway rope according to claim 1, characterized in that: The thickness of the ferrite lamellar layer at the surface of the wire rod is 0.04μm to 0.06μm, the thickness of the ferrite lamellar layer at 1 / 4 diameter from the surface is 0.06μm to 0.08μm, and the thickness of the ferrite lamellar layer at the core is 0.08μm to 0.10μm.

4. A method for preparing the ultra-high strength wire rod for cableway ropes according to 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 furnace time is 3.6h to 4.1h; the soaking section temperature is 1180°C to 1210°C, and the holding time is 45min to 55min; after the continuous casting billet is heated, continuous rolling is performed, and the final rolling temperature is 930°C to 980°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 cooling of the wire rod, the wire rod is cooled on an air-cooled roller after spinning to obtain the wire rod for the ultra-high strength cableway rope.

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 2% to 13%; the oxygen activity of the molten steel after converter smelting is controlled at 160ppm to 200ppm.

6. The preparation method according to claim 4, characterized in that: In the LF refining, the molten steel discharged from the converter is put into the LF furnace for refining treatment. The refining temperature of the LF furnace is 1410° C. to 1490° C., and the refining time is 30 min to 50 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)×(360mm-400mm); the pulling speed during the continuous casting process is 0.60m / min-0.80m / min, and the superheat degree of the molten steel in the tundish is 10°C-30°C.

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 ≤30μm, the size of inclusions at a position 1 / 4 of the thickness of the continuous rolling billet from the surface is ≤25μm, and the size of inclusions at the surface of the continuous rolling billet is ≤23μm; the mass percentage of Al2O3 in the inclusions is 5%-30%, the mass percentage of MgO is 5%-15%, and the mass percentage of FeO is 1%-5%; the mass percentage of FeO oxide scale on the surface of the continuous rolling billet is 50%-70%.

9. The preparation method according to claim 4, characterized in that: During the wire rod rolling, the total furnace time of the steel billet is 150min-160min, the temperature of the soaking section is 1100℃-1140℃, and the insulation time of the steel billet soaking section is 40min-80min; after the steel billet is heated, the mass percentage of surface iron oxide FeO is ≥60%, and the mass percentage of Fe2O3 is ≤10%; after rough rolling, intermediate rolling, pre-finishing rolling and finishing rolling, the wire rod spinning operation is carried out; the pre-finishing rolling temperature of the wire rod is 980℃-995℃; the finishing rolling temperature is 850℃-930℃; the double module temperature is 910℃-940℃; the wire rod spinning temperature is 910℃-940℃.

10. The preparation method according to claim 4, characterized in that: During the cooling of the wire rod, the wire rod is cooled on an air-cooled roller after spinning, and the phase change temperature of the wire rod is controlled to be 620°C to 670°C, and the phase change time of the wire rod on the air-cooled line is 15 to 25s; after the temperature of the wire rod on the air-cooled roller is less than 600°C, the cooling rate is 5°C / s to 10°C / s, and the wire rod coiling temperature is 180°C to 300°C.

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