Vanadium-containing high-strength bridge cable steel and preparation method thereof

Abstract

The invention discloses vanadium-containing high-strength bridge cable steel and a preparation method thereof, and belongs to the technical field of steel rolling, the vanadium-containing high-strength bridge cable steel mainly comprises 0.87%-0.89% of C, 0.75%-0.85% of Si, 0.71%-0.76% of Mn, 0.28%-0.32% of Cr, 0.010%-0.030% of Ti and 0.045%-0.055% of V; and the balance of Fe and inevitable impurities. After being pretreated, molten iron is sequentially subjected to converter smelting, refining and vacuum treatment; molten steel is fed into a continuous casting machine for blank casting and then rolled into square billets through a rolling mill, and finally the square billets are rolled into wire rods. The synergistic effect is formed by means of comprehensive component design, technological parameter adjustment, raw material replacement and the like, surface cracks of the bridge cable steel are improved by reducing the phosphorus content, meanwhile, the continuous casting water distribution strength and the production speed are adjusted to balance middle cracks and core segregation of the bridge cable steel, and the crack occurrence rate of the bridge cable steel is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of steel rolling, and particularly relates to a vanadium-containing high-strength bridge cable steel and a preparation method thereof. Background Art

[0002] The sizing machine is used for sizing the finished steel plate. It operates frequently and has high precision requirements. The control cables and pipeline air pipes on the sizing machine are all centrally arranged in the cable drag chain. When the sizing machine moves, the cable drag chain moves synchronously with the sizing trolley. There are idler rollers arranged below the cable drag chain. The idler rollers usually adopt iron rollers, which have disadvantages such as poor wear resistance, jamming, and inflexible rotation, resulting in the situation that the cable drag often sags or cannot be restored to its original position, thus causing the sizing machine to stop operating and affecting the stability of the production rhythm and quality. Summary of the Invention

[0003] Technical problem to be solved: Aiming at the technical problems existing in the operation of the cable drag chain of the sizing machine in the prior art, the present invention provides a vanadium-containing high-strength bridge cable steel and a preparation method thereof. The support device is correspondingly provided with a damping component for the support roller. The damping component can provide appropriate rotational resistance for the support roller, ensure that the support roller rotates flexibly, has self-lubricating shock absorption and low noise during use, and effectively ensures the normal and stable operation of the sizing machine.

[0004] Technical solution: A vanadium-containing high-strength bridge cable steel described in the present invention includes chemical components in parts by weight: C: 0.87 - 0.89%, Si: 0.75 - 0.85%, Mn: 0.71 - 0.76%, P≤0.010%, S≤0.010%, Cr: 0.28 - 0.32%, Ti: 0.010 - 0.030%, V: 0.045 - 0.055%; the rest is Fe and inevitable impurities.

[0005] The present invention also discloses a preparation method of a vanadium-containing high-strength bridge cable steel, including the following steps: Step 1: After the hot metal pretreatment, it successively undergoes converter smelting, LF furnace refining, and RH vacuum treatment to obtain the target molten steel; Step 2: Feed the target molten steel obtained in Step 1 into a continuous caster for casting billets to obtain slab billets; Step 3: Heat the slab billets obtained in Step 2, roll them into square billets through a rolling mill, and then roll the square billets into wire rods.

[0006] Preferably, the phosphorus content in the pretreated hot metal in Step 1 is below 0.003 wt%, and the sulfur content is below 0.001 wt%.

[0007] Preferably, the specific method for the phosphorus content of the molten iron in step 1 is as follows: the initial refining temperature of the molten steel is reduced from 1630 °C to 1590 °C, and lime raw stones with an equivalent ratio of weight are used to replace lime and added to the converter for dephosphorization.

[0008] Preferably, when tapping the converter in step 1, the carbon content of the molten steel is above 0.65 wt%, and the molten steel is alloyed to increase the vanadium element content of the molten steel, and then enters the LF furnace for refining.

[0009] Preferably, when the continuous caster is casting in step 2, the casting speed is 2.1 m / min and the water distribution for continuous casting is 1.37 Kg / L; the dynamic soft reduction process is adopted at the end of solidification, and the total reduction amount of the slab is 15 - 20 mm.

[0010] Preferably, in step 3, the soaking temperature of the slab is 1120 - 1170 °C and the heating time is 120 - 220 min.

[0011] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The method of the present invention combines multi-dimensional means such as composition design, process parameter adjustment, and raw material substitution to form a synergistic effect. By strictly controlling specific parameters such as the phosphorus content ≤0.010%, the water distribution intensity for continuous casting adjusted to 1.37 L / kg, and the production speed reduced from 2.8 m / min to 2.1 m / min, the surface cracks of the bridge cable steel are improved by reducing the phosphorus content, and at the same time, the water distribution intensity for continuous casting and the production speed are adjusted to balance the middle cracks and core segregation of the bridge cable steel, solving the problems of surface cracks, middle cracks, and core segregation of the bridge cable cylinder. The incidence rate of surface cracks of the bridge cable steel is reduced from 100% to 0%, the incidence rate of middle cracks is reduced from 100% to 4%, and the segregation index is optimized from 1.38 to 1.12: 2. During the converter smelting process, lime raw stones are used to replace lime, achieving the dual effects of temperature reduction and dephosphorization through an endothermic reaction; clarifying the composition range (such as V: 0.045 - 0.055%) and process parameters (such as the initial refining temperature of 1590 °C) of the bridge cable steel provides operable guidance and has the potential for industrial promotion; the method involves conventional smelting equipment (converter / electric furnace, continuous caster), and parameter adjustment (such as temperature, water distribution intensity) and production speed control can be achieved in existing production lines without special equipment.

[0012] Other beneficial effects of the present invention are stated in the embodiment part of the specification and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the preparation process of the bridge cable steel of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be combined with the attached Figure 1 The technical solutions of the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0015] Example 1: As Figure 1 shown, the vanadium-containing high-strength bridge cable steel provided by the present invention includes chemical components in parts by weight: C 0.875%, Si 0.76%, Mn 0.72%, P≤0.010%, S≤0.010%, Cr 0.28%, Ti 0.015%, V 0.048%; the rest is Fe and inevitable impurities. Its preparation method includes the following steps: (1) After the hot metal pretreatment, it is successively passed through converter smelting, LF furnace refining, and RH vacuum treatment to obtain the target molten steel. The phosphorus content in the pretreated hot metal is below 0.008 wt%, and the sulfur content is below 0.007 wt%; the specific method for the phosphorus content in the hot metal is: reducing the initial melting temperature of the molten steel from 1630°C to 1590°C, and using lime raw stones with an equivalent ratio by weight instead of lime to be added to the converter for dephosphorization, achieving the dual effects of temperature reduction and dephosphorization through an endothermic reaction, reducing the phosphorus content and improving the surface cracks of the bridge cable steel. When tapping from the converter, the carbon content in the molten steel is above 0.65 wt%, and the molten steel is alloyed to increase the vanadium element content in the molten steel, controlling the vanadium content at 0.048%, and then entering the LF furnace for refining.

[0016] (2) The obtained target molten steel is sent into a continuous caster for casting billets. When casting in the continuous caster, the casting speed is 2.1 m / min, and the continuous casting water distribution is 1.37 Kg / L; a dynamic soft reduction process is adopted at the end of solidification, and the total reduction of the billet is 18 mm to obtain slab billets.

[0017] (3) The obtained slab billets are heated. The soaking temperature of the billets is 1130°C, and the heating time is 140 min. They are rolled into square billets by a rolling mill, and then the square billets are rolled into wire rods.

[0018] Example 2: As Figure 1 shown, the vanadium-containing high-strength bridge cable steel provided by the present invention includes chemical components in parts by weight: C 0.881%, Si 0.82%, Mn 0.73%, P≤0.010%, S≤0.010%, Cr 0.31%, Ti 0.023%, V 0.049%; the rest is Fe and inevitable impurities. Its preparation method includes the following steps: (1) After the hot metal pretreatment, the target molten steel is obtained through converter smelting, LF furnace refining, and RH vacuum treatment in sequence. The phosphorus content in the pretreated hot metal is below 0.003 wt%, and the sulfur content is below 0.001 wt%. The specific method for the phosphorus content in the hot metal is as follows: lower the initial smelting temperature of the molten steel from 1630 °C to 1590 °C, and use lime raw stone with an equivalent ratio weight instead of lime to be added into the converter for dephosphorization. The cooling and dephosphorization double effects are achieved through an endothermic reaction, reducing the phosphorus content and improving the surface cracks of the bridge cable steel. When tapping from the converter, the carbon content in the molten steel is above 0.65 wt%, and alloying is carried out on the molten steel to increase the vanadium element content in the molten steel, controlling the vanadium content at 0.049%, and then entering the LF furnace for refining.

[0019] (2) The obtained target molten steel is sent into a continuous caster for casting billets. When casting in the continuous caster, the drawing speed is 2.1 m / min, and the continuous casting water distribution is 1.37 Kg / L. The dynamic soft reduction process is adopted at the solidification end, and the total reduction amount of the billet is 18 mm to obtain a slab.

[0020] (3) The obtained slab is heated. The soaking temperature of the billet is 1140 °C, and the heating time is 180 min. It is rolled into a square billet by a rolling mill, and then the square billet is rolled into a wire rod.

[0021] Example 3: As Figure 1 shown, the vanadium-containing high-strength bridge cable steel provided by the present invention includes chemical components in parts by weight: C 0.887%, Si 0.84%, Mn 0.75%, P≤0.010%, S≤0.010%, Cr 0.0.32%, Ti 0.029%, V0.053%; the rest are Fe and inevitable impurities. Its preparation method includes the following steps: (1) After the hot metal pretreatment, the target molten steel is obtained through converter smelting, LF furnace refining, and RH vacuum treatment in sequence. The phosphorus content in the pretreated hot metal is below 0.006 wt%, and the sulfur content is below 0.006 wt%. The specific method for the phosphorus content in the hot metal is as follows: lower the initial smelting temperature of the molten steel from 1630 °C to 1590 °C, and use lime raw stone with an equivalent ratio weight instead of lime to be added into the converter for dephosphorization. The cooling and dephosphorization double effects are achieved through an endothermic reaction, reducing the phosphorus content and improving the surface cracks of the bridge cable steel. When tapping from the converter, the carbon content in the molten steel is above 0.65 wt%, and alloying is carried out on the molten steel to increase the vanadium element content in the molten steel, controlling the vanadium content at 0.053%, and then entering the LF furnace for refining.

[0022] (2) The obtained target molten steel is sent into a continuous caster for casting billets. When casting in the continuous caster, the drawing speed is 2.1 m / min, and the continuous casting water distribution is 1.37 Kg / L. The dynamic soft reduction process is adopted at the solidification end, and the total reduction amount of the billet is 18 mm to obtain a slab.

[0023] (3) Heat the obtained slab. The soaking temperature of the continuous casting billet is 1165 °C and the heating time is 220 min. Roll the slab into a square billet through a rolling mill, and then roll the square billet into a wire rod.

[0024] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A vanadium-containing high-strength bridge cable steel, characterized in that, The chemical components in parts by weight include: C: 0.87 - 0.89%, Si: 0.75 - 0.85%, Mn: 0.71 - 0.76%, P ≤ 0.010%, S ≤ 0.010%, Cr: 0.28 - 0.32%, Ti: 0.010 - 0.030%, V: 0.045 - 0.055%; the balance is Fe and unavoidable impurities.

2. A preparation method of a vanadium-containing high-strength bridge cable steel as described in claim 1, characterized in that, It includes the following steps: Step 1: After the hot metal pretreatment, it successively undergoes converter smelting, LF furnace refining, and RH vacuum treatment to obtain the target molten steel. Step 2: Feed the target molten steel obtained in Step 1 into a continuous caster for casting billets to obtain slab billets. Step 3: Heat the slab billets obtained in Step 2, roll them into square billets through a rolling mill, and then roll the square billets into wire rods.

3. The preparation method of the vanadium-containing high-strength bridge cable steel according to claim 2, characterized in that, In Step 1, the phosphorus content in the pretreated hot metal is below 0.003 wt%, and the sulfur content is below 0.001 wt%.

4. The preparation method of the vanadium-containing high-strength bridge cable steel according to claim 3, characterized in that The specific method for the phosphorus content in the hot metal in Step 1 is: lower the initial smelting temperature of the molten steel from 1630 °C to 1590 °C, and use equivalent proportioned limestone instead of lime and add it to the converter for dephosphorization.

5. The preparation method of the vanadium-containing high-strength bridge cable steel according to claim 2, characterized in that, When tapping the converter in Step 1, the carbon content in the molten steel is above 0.65 wt%, alloy the molten steel to increase the vanadium element content in the molten steel, and then enter the LF furnace for refining.

6. The preparation method of the vanadium-containing high-strength bridge cable steel according to claim 2, characterized in that In Step 2, when casting with the continuous caster, the casting speed is 2.1 m / min, and the water distribution for continuous casting is 1.37 Kg / L; adopt the dynamic soft reduction process at the end of solidification, and the total reduction amount of the slab billet is 15 - 20 mm.

7. The preparation method of the vanadium-containing high-strength bridge cable steel according to claim 2, characterized in that, In Step 3, the soaking temperature of the slab billet is 1120 - 1170 °C, and the heating time is 120 - 220 min.

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