High-strength ultra-low-temperature wire rod and usage method therefor

Abstract

Disclosed in the present invention is a high-strength ultra-low-temperature wire rod. The wire rod comprises the following components in percentages by weight: C: 0.48-0.62%; Si: 0.01-0.03%; Mn: 9.8-28.5%; Cr: 3.15-5.23%; Ni: 8.5-16.3%; Mo: 0.2-1.8%; Cu≤0.15%; Ti≤0.012%; V≤0.02%; P≤0.002%; and S≤0.002%, with the balance being Fe and inevitable impurities. Compared with a Ni-based alloy, the present invention has the advantages of lower costs, and the strength being able to reach 600 MPa while meeting the requirement for toughness at a low temperature of -165ºC.

Description

High-strength ultralow-temperature wire rod and method of use thereof TECHNICAL FIELD

[0001] The present application relates to the field of steel, in particular to a high-strength ultralow-temperature wire rod and method of use thereof. BACKGROUND

[0002] The energy industry is the foundation of industry, and the transportation of energy is an important part. In order to efficiently and safely transport energy such as oil and natural gas, chemical raw materials, etc., it is often necessary to liquefy these materials and fill them into storage tanks, and the liquefaction temperature point of these energy materials is very low, so pressure-resistant and low-temperature-resistant steel plates and welding materials must be used to make the storage tanks.

[0003] High-strength low-temperature-resistant steel plates can greatly reduce the self-weight of the storage tank and improve the storage and transportation efficiency compared to ordinary low-temperature-resistant steel plates, but at the same time, high-strength low-temperature-resistant welding materials are needed. Most welding materials are made by drawing and subsequent processing of wire rods, so the development of high-strength ultralow-temperature wire rods is the focus of the industry, and the key is the innovation of the composition. "CN95103056.6" designs a high-strength high-toughness composition that can be used to make welding material wire rods for high-pressure storage tanks. By adding about 3% Ni and about 0.5% Mo, the strength of the material is improved and the toughness is ensured, and the strength can reach 800 MPa, but it can only be used in service environments of-40 DEG C and above; "CN202010157399.X" proposes a composition of 12% Ni, 18% Cr, and ultra-low C content to promote the formation of austenite to meet the requirements of-165 DEG C low-temperature toughness service, but the material strength is insufficient and can only be matched with storage tanks with a strength of about 500 MPa; "CN201710432013.X" discloses an ultralow-temperature composition that mainly promotes the formation of austenite through high Mn design, and the material strength can reach 650 MPa and the service temperature can reach-196 DEG C, but the molten pool flowability is poor during welding due to the high Mn content, making it difficult to achieve good forming effect. Many inventors use Ni-based alloys for composition design, but such compositions are expensive and greatly increase production costs.

[0004] Therefore, it is necessary to develop high-strength ultralow-temperature wire rods and methods of use thereof, which are low-temperature-resistant and high-strength, and cost-effective.

[0005] SUMMARY

[0006] The present application provides a high-strength ultralow-temperature wire rod and method of use thereof, which is more cost-effective than Ni-based alloys, meets-165 DEG C low-temperature toughness, and has a strength of 600 MPa.

[0007] Technical solution: The high-strength ultra-low temperature wire rod of the application is characterized in that the wire rod comprises the following components in percentage by weight: C is 0.48% to 0.62%, Si is 0.01% to 0.03%, Mn is 9.8% to 28.5%, Cr is 3.15% to 5.23%, Ni is 8.5% to 16.3%, Mo is 0.2% to 1.8%, Cu is less than or equal to 0.15%, Ti is less than or equal to 0.012%, V is less than or equal to 0.02%, P is less than or equal to 0.002%, S is less than or equal to 0.002%, and the balance is Fe and inevitable impurities.

[0008] In the preparation, the raw materials are smelted into molten steel, and then the square billets of 180mm are prepared by continuous casting; the square billets are placed in a heating furnace for 4h at 600℃, and then are sent to a wire rod rolling unit to be rolled into wire rods of Φ6.5mm at a temperature of 810℃ to 830℃, and then are air-cooled after rolling.

[0009] In the preparation, the raw materials are smelted into molten steel, and then the square billets of 180mm are prepared by continuous casting; the square billets are placed in a heating furnace for 4h at 600℃, and then are sent to a wire rod rolling unit to be rolled into wire rods of Φ6.5mm at a temperature of 810℃ to 830℃, and then are air-cooled after rolling.

[0010] In the preparation, the raw materials are smelted into molten steel, and then the square billets of 180mm are prepared by continuous casting; the square billets are placed in a heating furnace for 4h at 600℃, and then are sent to a wire rod rolling unit to be rolled into wire rods of Φ6.5mm at a temperature of 810℃ to 830℃, and then are air-cooled after rolling.

[0011] In the preparation, the raw materials are smelted into molten steel, and then the square billets of 180mm are prepared by continuous casting; the square billets are placed in a heating furnace for 4h at 600℃, and then are sent to a wire rod rolling unit to be rolled into wire rods of Φ6.5mm at a temperature of 810℃ to 830℃, and then are air-cooled after rolling.

[0012] Advantages: Compared with the prior art, the application has the following advantages: the application adopts high-carbon design, meets the requirement of strength of 600MPa, reduces the addition of other alloys, and reduces the cost. The application adds Cr and Mo alloy elements, can refine the grains of the weld, and improves the strength, but too much Mo element will lead to insufficient toughness and poor plasticity. The application places the square billets in a heating furnace for 4h at 600℃, and then sends them to a wire rod rolling unit, which can ensure the temperature homogenization of the square billets, and can avoid the rolling defects caused by too large temperature difference at different positions in the subsequent heating and rolling process. The application rolls the square billets into wire rods of Φ6.5mm at a temperature of 810℃ to 830℃, which is the best temperature interval for the plasticity of the composition, and air-cools after rolling, which effectively inhibits the precipitation of carbides. Specific implementation

[0013] The technical solution of the application is further described below in combination with the specific implementation.

[0014] Example 1:

[0015] The high-strength super-low-temperature wire rod of the embodiment has the following chemical components: C is 0.48wt%, Si is 0.02wt%, Mn is 9.8wt%, Cr is 4.25wt%, Ni is 16.3wt%, Mo is 1.8wt%, Cu≤0.15wt%, Ti≤0.012wt%, V≤0.02wt%, P≤0.002wt%, S≤0.002wt%, and the balance is Fe and inevitable impurities.

[0016] The molten steel with the above chemical components is smelted, and a 180mm square billet is formed by continuous casting. The square billet is placed in a heating furnace at 600℃ for 4h, and then is sent to a wire rod rolling unit to be rolled into a Φ6.5mm wire rod at a temperature of 810℃-830℃, and is air-cooled after rolling.

[0017] The wire rod is uncoiled and mechanically drawn to remove the surface oxide skin. Then, the wire rod is reduced in diameter from Φ6.5mm to Φ3.5mm through three drawing processes, and then is annealed. After annealing, the wire rod is again reduced in diameter from Φ3.5mm to Φ1.5mm through three drawing processes, and finally is fine-drawn to Φ1.2mm to form the gas shielded welding wire.

[0018] The above gas shielded welding wire is subjected to deposited metal detection.

[0019] The welding wire is welded under the protection of 80% Ar+20% CO2 by volume, with a welding current of 140A-180A and a voltage of 22V-28V. The obtained weld metal has a low-temperature impact of 88, 78, 78J at -165℃, and a strength of 617MPa.

[0020] Embodiment 2:

[0021] The high-strength super-low-temperature wire rod of the embodiment has the following chemical components: C is 0.62wt%, Si is 0.01wt%, Mn is 28.5wt%, Cr is 3.15wt%, Ni is 8.5wt%, Mo is 0.2wt%, Cu≤0.15wt%, Ti≤0.012wt%, V≤0.02wt%, P≤0.002wt%, S≤0.002wt%, and the balance is Fe and inevitable impurities.

[0022] The molten steel with the above chemical components is smelted, and a 180mm square billet is formed by continuous casting. The square billet is placed in a heating furnace at 600℃ for 4h, and then is sent to a wire rod rolling unit to be rolled into a Φ6.5mm wire rod at a temperature of 810℃-830℃, and is air-cooled after rolling.

[0023] The wire rod is uncoiled and mechanically drawn to remove the surface oxide skin. Then, the wire rod is reduced in diameter from Φ6.5mm to Φ3.5mm through three drawing processes, and then is annealed. After annealing, the wire rod is again reduced in diameter from Φ3.5mm to Φ1.5mm through three drawing processes, and finally is fine-drawn to Φ1.2mm to form the gas shielded welding wire. The wire rod is uncoiled and mechanically drawn to remove the surface oxide skin. Then, the wire rod is reduced in diameter from Φ6.5mm to Φ3.5mm through three drawing processes, and then is annealed. After annealing, the wire rod is again reduced in diameter from Φ3.5mm to Φ1.5mm through three drawing processes, and finally is fine-drawn to Φ1.2mm to form the gas shielded welding wire.

[0024] The gas shielded welding wire is subjected to deposited metal detection.

[0025] The welding current is 140A-180A, the voltage is 22V-28V, the obtained weld metal is 64, 58, 66J at-165℃ low temperature impact, and the strength is 640MPa.

[0026] Example 3:

[0027] The chemical components of the high-strength ultra-low-temperature wire rod of the embodiment are: C is 0.55wt%, Si is 0.03wt%, Mn is 19.6wt%, Cr is 5.23wt%, Ni is 12.5wt%, Mo is 1.2wt%, Cu≤0.15wt%, Ti≤0.012wt%, V≤0.02wt%, P≤0.002wt%, S≤0.002wt%, and the balance is Fe and inevitable impurities.

[0028] The above chemical components are used for molten steel smelting, and a 180mm square billet is made by continuous casting. The square billet is placed in a heating furnace at 600℃ for 4h and then sent to a wire rod rolling mill to be rolled into a Φ6.5mm wire rod at a temperature of 810℃-830℃, and air-cooled after rolling.

[0029] The wire rod is uncoiled and mechanically drawn to remove the surface oxide skin. Then it is reduced in diameter from Φ6.5mm to Φ3.5mm by three drawing, and then annealed, and after annealing, it is again reduced in diameter from Φ3.5mm to Φ1.5mm by three drawing, and finally fine-drawn to Φ1.2mm to make a gas shielded welding wire.

[0030] The gas shielded welding wire is subjected to deposited metal detection.

[0031] The welding current is 140A-180A, the voltage is 22V-28V, the obtained weld metal is 64, 58, 66J at-165℃ low temperature impact, and the strength is 640MPa.

Claims

1. A high strength ultra low temperature wire rod characterized by: The wire rod comprises the following weight percentages of components: C 0.48-0.62%, Si 0.01-0.03%, Mn 9.8-28.5%, Cr 3.15-5.23%, Ni 8.5-16.3%, Mo 0.2-1.8%, Cu ≤0.15%, Ti ≤0.012%, V ≤0.02%, P ≤0.002%, S ≤0.002%, the balance being Fe and unavoidable impurities.

2. The high strength super low temperature wire rod as claimed in claim 1, characterized in that: In the preparation, the raw materials are subjected to molten steel smelting to form a 180mm square billet; the square billet is placed in a heating furnace for 4h at 600℃, and then is sent to a wire rod rolling unit to be rolled into a Φ6.5mm wire rod at a temperature of 810-830℃, and is air-cooled after rolling.

3. The method of use of high strength ultra low temperature wire rod according to claim 1 or 2, characterized in that: The wire rod is uncoiled and mechanically drawn to remove the surface oxide scale; then is reduced in diameter from Φ6.5mm to Φ3.5mm through three drawing processes, and then is annealed, and after annealing, is again reduced in diameter from Φ3.5mm to Φ1.5mm through three drawing processes, and finally is fine-drawn to Φ1.2mm to form the gas shielded welding wire.

4. The method of use of high strength super low temperature wire rod as claimed in claim 3, wherein: The gas shielded welding wire is protected by 80% Ar+20% CO2 in volume percentage, the welding current is 140-180A, and the voltage is 22-28V.

5. The method of using high strength super low temperature wire rod as claimed in claim 3, wherein: The weld formed by welding the gas shielded welding wire satisfies the low-temperature toughness of-165℃, and the strength reaches 600MPa.