A production method of a high-strength nickel-free rare earth weathering steel

Abstract

The application discloses a production method of high-strength nickel-free rare earth weather-resistant steel, and mainly comprises the following process parameters: (1) a smelting-continuous casting production process; and (2) a hot rolling production process: casting blank-induction heating furnace-laboratory rolling mill-laminar flow cooling-simulated coiling; the casting blank is discharged at a temperature of 1240±20 DEG C, the final rolling temperature of finish rolling is 890-900 DEG C, the cold speed is 10-20 DEG C / S, and the thickness of the hot rolled steel strip is 2-3 mm; the cooling adopts laminar flow cooling equipment, a front dispersion cooling mode, and the coiling temperature is 590±10 DEG C. The application aims to provide a production method of high-strength nickel-free rare earth weather-resistant steel, adopts a conventional C Si Mn component system design, and adds corrosion-resistant elements Cu, Cr, P and a small amount of La / Ce mixed rare earth to improve the corrosion resistance of the steel strip.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical plate production technology, and particularly relates to a production method of high-strength nickel-free rare earth weathering steel. Background Technology

[0002] Construction projects still primarily rely on applying anti-corrosion coatings and using galvanized products. However, hot-dip galvanizing for corrosion protection requires processes such as rust removal, pickling, and galvanizing, resulting in significant investment. Furthermore, the zinc bath needs to be heated to high temperatures, releasing harmful gases that endanger human health, especially in the zinc passivation solution, posing a considerable risk to both human health and the environment. Therefore, replacing galvanized products with weathering steel is an inevitable trend.

[0003] Currently, weathering steel is widely used in the manufacture of various engineering vehicles, tank cars, containers, and railway vehicles in my country, primarily employing steel plates with tensile strengths of 520 and 750. In recent years, to reduce weight and increase load capacity, various vehicles have been developing towards "larger size and lighter weight." The product of this invention possesses excellent properties such as high strength, high toughness and plasticity, high corrosion resistance, and good machinability, meeting the requirements for steel used in highway guardrails. This type of product has a very promising market prospect. Summary of the Invention

[0004] The purpose of this invention is to provide a production method for high-strength nickel-free rare earth weathering steel. The method adopts a conventional CSiMn composition system and improves the corrosion resistance of the steel strip by adding corrosion-resistant elements Cu, Cr, P and a small amount of La / Ce mixed rare earth.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention discloses a method for producing high-strength nickel-free rare-earth weathering steel, the main process parameters of which include:

[0007] (1) Smelting-continuous casting production process: The composition of molten steel by mass percentage is C: 0.12-0.15%, Si: 0.40-0.50%, Mn: 0.8-0.9%, P: 0.02-0.03%, S: ≤0.008%, Cu: 0.25-0.30%, Cr: 0.60-0.70%, La / Ce: 40-55ppm, Alt: 0.020-0.050%; the remainder is Fe and impurities;

[0008] (2) Hot rolling production process: billet - induction heating furnace - laboratory mill - laminar flow cooling - simulated coiling; billet exit temperature is 1240±20℃, finishing rolling temperature is 890-900℃, cooling rate is 10-20℃ / S, hot rolled steel strip thickness is 2-3mm; cooling adopts laminar flow cooling equipment, front-dispersed cooling mode, coiling temperature is 590±10℃.

[0009] Furthermore, the slab is heated to 1250℃ for 40 minutes and rolled using a hot continuous rolling mill; the finishing rolling temperature is 900℃, and the finished product thickness is 2.5mm; laminar flow cooling is achieved by pre-dispersion cooling at a rate of 20℃ / s, and the steel strip temperature is reduced to 593℃ before coiling; finally, product performance testing is performed.

[0010] Furthermore, the slab is heated to 1260℃ for 40 minutes and rolled using a hot continuous rolling mill; the finishing rolling temperature is 906℃, and the finished product thickness is 2.5mm; laminar flow cooling is achieved by pre-dispersive cooling at a rate of 19℃ / s, and the steel strip temperature is reduced to 600℃ before coiling; finally, product performance testing is performed.

[0011] Furthermore, the slab is heated to 1255℃ for 43 minutes and rolled on a hot continuous rolling mill; the finishing rolling temperature is 899℃ and the finished product thickness is 5mm; laminar flow cooling adopts pre-dispersion cooling at a cooling rate of 20℃ / s, and the steel strip temperature is reduced to 598℃ before coiling; finally, product performance testing is carried out.

[0012] Furthermore, the high-strength nickel-free rare earth weathering steel has the following composition by mass percentage: C: 0.12%, Si: 0.42%, Mn: 0.88%, P: 0.022%, S: 0.004%, Cu: 0.29%, Cr: 0.63%, La / Ce: 0.0052%, Alt: 0.032%; the remainder is Fe and impurities.

[0013] Furthermore, the high-strength nickel-free rare earth weathering steel has the following composition by mass percentage: C: 0.12%, Si: 0.42%, Mn: 0.88%, P: 0.023%, S: 0.003%, Cu: 0.30%, Cr: 0.66%, La / Ce: 0.0048%, Alt: 0.030%; the remainder is Fe and impurities.

[0014] Furthermore, the high-strength nickel-free rare earth weathering steel has the following composition by mass percentage: C: 0.12%, Si: 0.41%, Mn: 0.85%, P: 0.023%, S: 0.003%, Cu: 0.29%, Cr: 0.60%, La / Ce: 0.0053%, Alt: 0.031%; the remainder is Fe and impurities.

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

[0016] The metallographic microstructure of the steel grade of this invention consists of bainite, a small amount of ferrite, and a small amount of pearlite. A high-strength nickel-free rare-earth weathering steel produced using the method provided in this invention has been tested in the laboratory and its mechanical and technological properties meet relevant standards and user requirements. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings.

[0018] Figure 1 This is a microstructure diagram of Embodiment 1 of the present invention. Detailed Implementation

[0019] The present invention will be described in more detail below through specific embodiments. These embodiments are merely descriptions of the best implementation of the invention and do not limit the scope of the invention in any way.

[0020] Example 1

[0021] The smelting was carried out in a laboratory furnace. The slab was heated to 1250℃ for 40 minutes and rolled using a hot continuous rolling mill. The finishing rolling temperature was 900℃, and the finished product thickness was 2.5mm. Laminar flow cooling was performed using pre-dispersion cooling at a rate of 20℃ / s, and the steel strip temperature was reduced to 593℃ before coiling. Finally, product performance testing was conducted.

[0022] Example 2

[0023] The smelting was carried out in a laboratory furnace. The slab was heated to 1260℃ for 40 minutes and rolled using a hot continuous rolling mill. The finishing rolling temperature was 906℃, and the finished product thickness was 2.5mm. Laminar flow cooling was performed using pre-dispersion cooling at a rate of 19℃ / s, and the strip temperature was reduced to 600℃ before coiling. Finally, product performance testing was conducted.

[0024] Example 3

[0025] The smelting was carried out in a laboratory furnace. The slab was heated to 1255℃ for 43 minutes, and then rolled on a hot strip mill. The finishing rolling temperature was 899℃, and the finished product thickness was 5mm. Laminar flow cooling was performed using pre-dispersion cooling at a rate of 20℃ / s, and the strip temperature was reduced to 598℃ before coiling. Finally, product performance testing was conducted.

[0026] Comparative Example 1

[0027] The smelting was carried out in a laboratory furnace. The slab was heated to 1240℃ for 50 minutes and rolled using a hot continuous rolling mill. The finishing rolling temperature was 901℃, and the finished product thickness was 5mm. Laminar flow cooling was performed using pre-dispersion cooling at a rate of 18℃ / s, and the steel strip temperature was reduced to 600℃ before coiling. Finally, product performance testing was conducted.

[0028] Table 1. Chemical composition (wt%) of Examples 1-3 of the present invention

[0029]

[0030] The mechanical properties of the steel coils in Examples 1 to 3 of the present invention were tested, and the test results are shown in Table 2.

[0031] Table 2 Mechanical properties of steel coils from Examples 1-3 of the present invention

[0032]

[0033] As shown in Table 2, the mechanical and technological properties of the steel for the paint-free photovoltaic bracket produced according to the method provided by this invention meet the requirements of the agreement signed with the user.

[0034] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for producing a high-strength nickel-free rare earth weathering steel, characterized by: The main process parameters include: (1) Smelting-continuous casting process flow: the composition of the molten steel in percentage by mass is C: 0.12%, Si: 0.42%, Mn: 0.88%, P: 0.022%, S: 0.004%, Cu: 0.29%, Cr: 0.63%, La / Ce: 0.0052%, Alt: 0.032%; the rest is Fe and impurities; (2) Hot rolling process flow: casting blank-induction heating furnace-laboratory rolling mill-laminar flow cooling-simulated coiling; the slab heating temperature is 1250 DEG C, the heating time is 40 min, and hot continuous rolling mill is used for rolling; the finish rolling temperature is 900 DEG C, and the finished product thickness is 2.5 mm; the laminar flow cooling adopts front dispersion cooling, the cooling speed is 20 DEG C / S, and the steel strip temperature is reduced to 593 DEG C for coiling; Product properties: yield strength R p0.2 was 756 MPa, tensile strength R m was 902 MPa, elongation A was 18.5%, and low-temperature impact property at -40°C was 178 J.

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