Production method of rare earth high-carbon steel wire rod

Abstract

The invention discloses a production method of a rare earth high-carbon steel wire rod, the rare earth high-carbon steel wire rod comprises the following chemical components in percentage by mass: 0.85-0.90% of C, 1.0-1.2% of Si, 0.30-0.50% of Mn, 0.01-0.0.03% of V, 10-30 ppm of rare earth RE, and the balance of Fe and inevitable impurities, the content of P in the impurities is less than or equal to 0.015%, and the content of S in the impurities is less than or equal to 0.010%; the invention also discloses a specific production process. According to the production method of the rare earth high-carbon steel wire rod, the produced high-carbon steel wire rod is high in tensile strength, the high-strength requirement of a user is well met, and the tensile strength of the high-carbon steel wire rod is obviously superior to that of domestic comparative manufacturers.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a production method of a rare earth high carbon steel wire rod. Background Art

[0002] High carbon steel wire rod is mainly used to make steel wire rope, bridge cable, tire frame, galvanized steel wire and high strength low relaxation (SWRH) prestressed steel strand. These applications have high requirements on the strength and toughness of steel. With the rapid development of the construction and automobile industries, the demand for high strength and high durability steel is increasing, which will further promote the development of the high carbon wire rod market. At the same time, technological advances such as the development of new alloy elements and more efficient production technology will also open up new possibilities for the application of high carbon wire rod. However, the high carbon wire rod produced domestically has problems such as large fluctuations in tensile strength and unstable drawing performance. Summary of the invention

[0003] The purpose of the present invention is to provide a method for producing rare earth high carbon steel wire rod. The high carbon wire rod produced by the present invention has high tensile strength, which better meets the high strength requirements of users and is significantly better than the tensile strength of domestic comparison manufacturers.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention discloses a method for producing a rare earth high carbon steel wire rod. The chemical composition of the rare earth high carbon steel wire rod in terms of mass percentage includes: C 0.85-0.90%, Si 1.0-1.2%, Mn 0.30-0.50%, V 0.01-0.0.03%, rare earth RE content 10-30ppm, the balance is Fe and unavoidable impurities, P in the impurities is ≤0.015%, and S in the impurities is ≤0.010%. The production process includes:

[0006] Smelting process: Control the sulfur content in the molten iron below 0.005% to ensure the quality of the final product. Control the final phosphorus content ≤ 0.010%, and maintain a suitable tapping temperature to ensure that the molten steel has good fluidity and castability;

[0007] Refining: The refining temperature is controlled at 1530-1625℃ for 20-50 minutes to ensure the purity and uniformity of the molten steel. Refining is carried out under argon blowing throughout the process, and slag-making materials such as lime and calcium carbide are added. During the slag-making period of the aluminum-free deoxidation process, silicon-calcium-barium-magnesium composite deoxidizer is added to quickly remove oxygen from the steel. About 100-200 kg is added to each furnace. In the later stage of refining, the total oxygen content is controlled below 20ppm, and then rare earth alloys are added to ensure the recovery rate of rare earth alloys;

[0008] Continuous casting: small square billet continuous casting is adopted, and the superheat of molten steel in the tundish is not more than 30℃ to ensure the quality of continuous casting billet. The pulling speed adopts constant pulling speed to reduce center segregation and improve the internal quality of the billet. At the same time, protective pouring and electromagnetic stirring technology are adopted, with the electromagnetic stirring current of 580A and the frequency of 1.8Hz to improve the solidification structure of the billet and reduce the formation of core martensite and network cementite;

[0009] Rolling: including rough rolling, intermediate rolling and finishing rolling. Each stage has strict temperature and deformation control to ensure the organizational properties and dimensional accuracy of the wire rod. The starting rolling temperature is controlled at 1050-1100℃, and the wire drawing temperature is controlled at 870-900℃.

[0010] Cooling and air cooling: The temperature of the troostite transformation process of the wire rod is controlled at 640-600℃, the transformation time is controlled at 7-12 seconds, and the average supercooling degree is 60-80℃; the air cooling zone design uses precise control of four air cooling zones to make the temperature of the wire rod drop evenly by 10℃ / s, thereby refining the grains and improving strength and toughness.

[0011] Furthermore, the pulling speed was controlled to be constant at 2.1 m / min.

[0012] Furthermore, the chemical composition of the rare earth high carbon steel wire rod in terms of mass percentage includes: C 0.86%, Si 1.1%, Mn 0.37%, V 0.02%, rare earth RE content 15ppm, the remainder is Fe and unavoidable impurities, P in the impurities is 0.010%, and S in the impurities is 0.005%.

[0013] Furthermore, the chemical composition of the rare earth high carbon steel wire rod in terms of mass percentage includes: C 0.87%, Si 1.11%, Mn 0.38%, V 0.02%, rare earth RE content 13ppm, the remainder is Fe and unavoidable impurities, P in the impurities is 0.010%, and S in the impurities is 0.004%.

[0014] Furthermore, the chemical composition of the rare earth high carbon steel wire rod in terms of mass percentage includes: C 0.86%, Si 1.12%, Mn 0.39%, V 0.02%, rare earth RE content 12ppm, the remainder is Fe and unavoidable impurities, P in the impurities is 0.011%, and S in the impurities is 0.003%.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are:

[0016] The high carbon wire rod produced by the present invention has a high tensile strength, which satisfies the high strength requirements of users and is significantly better than the tensile strength of domestic manufacturers. At the same time, the addition of rare earth improves the wire rod's drawing property and corrosion resistance, which has obvious advantages. DETAILED DESCRIPTION

[0017] The main preparation process of a high carbon steel wire wire rod in this example is:

[0018] The Φ12.5mm wire rod is made by converter smelting, LF refining, billet continuous casting and wire rolling.

[0019] Table 1 Finished product composition (wt%, balance iron)

[0020] C Si Mn P S V RE(ppm) Example 1 0.86 1.1 0.37 0.010 0.005 0.02 15 Example 2 0.87 1.11 0.38 0.010 0.004 0.02 13 Example 3 0.86 1.12 0.39 0.011 0.003 0.02 12

[0021] Table 2 Rolling temperature control ℃

[0022] Rolling temperature Spinning temperature Example 1 1060 880 Example 2 1065 885 Example 3 1070 875

[0023] Table 3 Mechanical properties test

[0024]

[0025] It can be seen from the above table that the high carbon wire rod produced by the present invention has a high tensile strength, which better meets the high strength requirements of users and is significantly better than the tensile strength of domestic comparison manufacturers. At the same time, the addition of rare earth improves the wire rod's drawing properties and corrosion resistance. It has obvious advantages.

[0026] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for producing rare earth high carbon steel wire rod, characterized in that: The chemical composition of the rare earth high carbon steel wire rod in terms of mass percentage includes: C 0.85-0.90%, Si 1.0-1.2%, Mn 0.30-0.50%, V0.01-0.0.03%, rare earth RE content 10-30ppm, the balance is Fe and unavoidable impurities, P in the impurities is ≤0.015%, S in the impurities is ≤0.010%; its production process includes: Smelting process: Control the sulfur content in the molten iron below 0.005% to ensure the quality of the final product. Control the final phosphorus content ≤ 0.010%, and maintain a suitable tapping temperature to ensure that the molten steel has good fluidity and castability; Refining: The refining temperature is controlled at 1530-1625℃ for 20-50 minutes to ensure the purity and uniformity of the molten steel. Refining is carried out under argon blowing throughout the process, and slag-making materials such as lime and calcium carbide are added. During the slag-making period of the aluminum-free deoxidation process, silicon-calcium-barium-magnesium composite deoxidizer is added to quickly remove oxygen from the steel. About 100-200 kg is added to each furnace. In the later stage of refining, the total oxygen content is controlled below 20ppm, and then rare earth alloys are added to ensure the recovery rate of rare earth alloys; Continuous casting: small square billet continuous casting is adopted, and the superheat of molten steel in the tundish is not more than 30℃ to ensure the quality of continuous casting billet. The pulling speed adopts constant pulling speed to reduce center segregation and improve the internal quality of the billet. At the same time, protective pouring and electromagnetic stirring technology are adopted, with the electromagnetic stirring current of 580A and the frequency of 1.8Hz to improve the solidification structure of the billet and reduce the formation of core martensite and network cementite; Rolling: including rough rolling, intermediate rolling and finishing rolling. Each stage has strict temperature and deformation control to ensure the organizational properties and dimensional accuracy of the wire rod. The starting rolling temperature is controlled at 1050-1100℃, and the wire drawing temperature is controlled at 870-900℃. Cooling and air cooling: The temperature of the troostite transformation process of the wire rod is controlled at 640-600℃, the transformation time is controlled at 7-12 seconds, and the average supercooling degree is 60-80℃; the air cooling zone design uses precise control of four air cooling zones to make the temperature of the wire rod drop evenly by 10℃ / s, thereby refining the grains and improving strength and toughness.

2. The method for producing rare earth high carbon steel wire rod according to claim 1, characterized in that: Control the constant pulling speed to 2.1m / min.

3. The method for producing rare earth high carbon steel wire rod according to claim 1, characterized in that: The chemical composition of the rare earth high carbon steel wire rod in terms of mass percentage includes: C 0.86%, Si 1.1%, Mn 0.37%, V 0.02%, rare earth RE content 15ppm, the balance is Fe and unavoidable impurities, P in the impurities is 0.010%, and S in the impurities is 0.005%.

4. The method for producing rare earth high carbon steel wire rod according to claim 1, characterized in that: The chemical composition of the rare earth high carbon steel wire rod in terms of mass percentage includes: C 0.87%, Si 1.11%, Mn 0.38%, V 0.02%, rare earth RE content 13ppm, the balance is Fe and unavoidable impurities, P in the impurities is 0.010%, and S in the impurities is 0.004%.

5. The method for producing rare earth high carbon steel wire rod according to claim 1, characterized in that: The chemical composition of the rare earth high carbon steel wire rod in terms of mass percentage includes: C 0.86%, Si 1.12%, Mn 0.39%, V 0.02%, rare earth RE content 12ppm, the balance is Fe and unavoidable impurities, P in the impurities is 0.011%, and S in the impurities is 0.003%.

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