A low-cost, high-strength, low-density, corrosion-resistant bridge steel and its preparation method

Abstract

The present invention relates to the technical field of alloy materials, and particularly relates to a bridge steel with low cost, high strength, high toughness, low density and corrosion resistance, and a preparation method thereof. The present invention provides a bridge steel with low cost, high strength, high toughness, low density and corrosion resistance. The mass percentages of the chemical components of the bridge steel include: Mn: 13% - 15%, Cr: 0.4% - 1.0%, Al: 4% - 5%, Nb: 0.009% - 0.015%, V: 0.01% - 0.02%, Ti: 0.015% - 0.035%, Te: 0.035% - 0.35%, Sb: 0.05% - 0.25%, RE: 0.003% - 0.006%. The embodiments of the present invention provide a bridge steel with low cost, high strength, high toughness, low density and corrosion resistance and a preparation method thereof, which can provide a bridge steel with low cost, high strength, high toughness, low density and corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy materials, and particularly relates to a bridge steel with low cost, high strength, toughness, low density and corrosion resistance, and a preparation method thereof. Background Art

[0002] At present, carbon steel and alloy steel materials have relatively high strength, but often have defects such as high density, poor corrosion resistance and insufficient toughness. For example, in large structural components such as buildings, transportation, and bridges, the excessive density of steel will increase the overall weight of the components, thus having an adverse impact on the transportation, installation and subsequent maintenance of the materials. In addition, traditional steel has poor environmental adaptability, especially being easily corroded by factors such as air, moisture, and salt spray, resulting in shortened structure life and increased maintenance costs.

[0003] Therefore, in view of the above problems, there is an urgent need for a bridge steel with low cost, high strength, toughness, low density and corrosion resistance, and a preparation method thereof. Summary of the Invention

[0004] Embodiments of the present invention provide a bridge steel with low cost, high strength, toughness, low density and corrosion resistance, and a preparation method thereof, which can provide a bridge steel with low cost, high strength, toughness, low density and corrosion resistance.

[0005] In a first aspect, embodiments of the present invention provide a bridge steel with low cost, high strength, toughness, low density and corrosion resistance. The mass percentages of the chemical components of the bridge steel include: Mn: 13% - 15%, Cr: 0.4% - 1.0%, Al: 4% - 5%, Nb: 0.009% - 0.015%, V: 0.01% - 0.02%, Ti: 0.015% - 0.035%, Te: 0.035% - 0.35%, Sb: 0.05% - 0.25%, RE: 0.003% - 0.006%, and the balance is Fe and inevitable impurity elements.

[0006] In a possible design, the mass percentages of the chemical components of the bridge steel are: C: 0.07% - 0.10%, Si: 0.25% - 0.35%, Mn: 13% - 15%, P ≤ 0.01%, S ≤ 0.01%, Ni: 0.25% - 0.70%, Cr: 0.4% - 1.0%, Mo: 0.2% - 0.8%, Al: 4% - 5%, Cu: 0.3% - 0.55%, Nb: 0.009% - 0.015%, V: 0.01% - 0.02%, Ti: 0.015% - 0.035%, RE: 0.003% - 0.006%, Te: 0.035% - 0.35%, Sb: 0.05% - 0.25%, and the balance is Fe and inevitable impurity elements.

[0007] In a possible design, the following limiting conditions are satisfied:

[0008] 0.25 ≤ Al / Mn ≤ 0.4;

[0009] Wherein, Al / Mn represents the mass ratio of Al and Mn.

[0010] In a possible design, the following limiting conditions are satisfied:

[0011] 0.025% ≤ Nb + V + Ti ≤ 0.07%;

[0012] Wherein, Nb + V + Ti represents the sum of the mass percentages of Nb, V and Ti.

[0013] In a possible design, the following limiting conditions are satisfied:

[0014] 1.3% ≤ 0.1M Sb + 0.6M Al + 0.05M Te + 0.3M Cr ≤ 4.5%;

[0015] Wherein, M Sb , M Al , M Te , M Cr are the mass percentages of Sb, Al, Te, and Cr respectively.

[0016] In a possible design, RE includes La and Ce.

[0017] In a possible design, the mass ratio of La to Ce is (4~6):(4~6).

[0018] In a possible design, the microstructure is ferrite, austenite and lath martensite.

[0019] In a second aspect, an embodiment of the present invention provides a preparation method for a low-cost, high-strength, low-density and corrosion-resistant bridge steel for preparing any of the above bridge steels, and the preparation method includes:

[0020] Smelt each raw material by a vacuum induction furnace to obtain an ingot;

[0021] After forging the ingot, adopt a controlled rolling and controlled cooling process to obtain the bridge steel.

[0022] In a possible design, the forging temperature of the ingot is 1100~1200 °C, and the cooling method is slow cooling;

[0023] The controlled rolling and controlled cooling process includes: before rolling, the preheating temperature is controlled at 1200°C, the holding time is 2 hours. After holding for 2 hours, it is cooled in the furnace to 1000°C for rolling. The finishing rolling temperature is 870 - 890°C, rolling is carried out for 3 passes, the total reduction is 75%. Subsequently, it is water-cooled to about 450°C and then air-cooled to room temperature.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] In this embodiment, by adding Al and Mn, the equilibrium structure of the bridge steel is a duplex steel mainly composed of ferrite and supplemented by austenite. This duplex structure significantly improves the plasticity of the steel. The addition of alloying elements such as Nb, V, and Ti can improve the strength, hardness, corrosion resistance, and heat treatment performance of the steel. The addition of rare earth element RE can effectively refine the grains of the steel, which helps to improve the strength and toughness of the steel, and can form a stable oxide film (such as CeO2 and La2O3) on the steel surface. This film helps to improve the corrosion resistance of the steel. The addition of rare earth elements not only helps to remove harmful inclusions, but also can change the morphology of inclusions, making them more uniformly distributed and finer. By increasing the content of light elements Al and Mn and the composite regulation of various corrosion-resistant elements, the present invention can simultaneously improve the strength and plasticity of the steel, reduce the density of the steel, and improve the corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 [[ID=Is a microscopic image of a bridge steel provided in Embodiment 1 of the present invention;

[0028] Figure 2 Is a microscopic image of a bridge steel provided in Comparative Example 1 of the present invention;

[0029] Figure 3 Is a microscopic image of a bridge steel provided in Comparative Example 2 of the present invention;

[0030] Figure 4 Is the 3D corrosion morphology after rust removal of a bridge steel provided in Embodiment 1 of the present invention after 14 days of cyclic immersion test;

[0031] Figure 5 Is the 3D corrosion morphology after rust removal of a bridge steel provided in Comparative Example 1 of the present invention after 14 days of cyclic immersion test;

[0032] Figure 6 It is the 3D corrosion morphology after rust removal of a bridge steel provided in Comparative Example 2 of the present invention after 14 days of cyclic immersion test. Specific embodiments

[0033] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, 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 without creative efforts in the embodiments of the present invention belong to the scope of protection of the present invention.

[0034] Please refer to Figures 1 to 6 , the present invention provides a bridge steel with low cost, high strength, low density and corrosion resistance. The mass percentages of the chemical components of the bridge steel include: Mn: 13% - 15%, Cr: 0.4% - 1.0%, Al: 4% - 5%, Nb: 0.009% - 0.015%, V: 0.01% - 0.02%, Ti: 0.015% - 0.035%, Te: 0.035% - 0.35%, Sb: 0.05% - 0.25%, RE: 0.003% - 0.006%, and the rest are Fe and inevitable impurity elements.

[0035] In this embodiment, by adding Al and Mn, the equilibrium structure of the bridge steel is a duplex steel mainly composed of ferrite and supplemented by austenite. This duplex structure significantly improves the plasticity of the steel. The addition of alloying elements such as Nb, V, and Ti can improve the strength, hardness, corrosion resistance and heat treatment performance of the steel. The addition of rare earth element RE can effectively refine the grains of the steel, which helps to improve the strength and toughness of the steel and can form a stable oxide film (such as CeO2 and La2O3) on the steel surface. This film helps to improve the corrosion resistance of the steel. The addition of rare earth elements not only helps to remove harmful inclusions but also can change the morphology of inclusions, making them more evenly distributed and finer. By increasing the content of light elements Al and Mn and the composite regulation of various corrosion-resistant elements, the present invention can simultaneously improve the strength and plasticity of the steel, reduce the density of the steel, and improve the corrosion resistance.

[0036] In some embodiments of the present invention, the mass percentages of the chemical components of the bridge steel are as follows: C: 0.07% - 0.10%, Si: 0.25% - 0.35%, Mn: 13% - 15%, P ≤ 0.01%, S ≤ 0.01%, Ni: 0.25% - 0.70%, Cr: 0.4% - 1.0%, Mo: 0.2% - 0.8%, Al: 4% - 5%, Cu: 0.3% - 0.55%, Nb: 0.009% - 0.015%, V: 0.01% - 0.02%, Ti: 0.015% - 0.035%, RE: 0.003% - 0.006%, Te: 0.035% - 0.35%, Sb: 0.05% - 0.25%, and the balance is Fe and inevitable impurity elements.

[0037] In this embodiment, by compounding and adding elements such as Cu and Sb that improve the corrosion resistance, and through hot rolling and water cooling processes, the mechanical properties and corrosion resistance of the material can be improved.

[0038] In some embodiments of the present invention, the following limiting conditions are satisfied:

[0039] 0.25 ≤ Al / Mn ≤ 0.4;

[0040] Wherein, Al / Mn represents the mass ratio of Al and Mn.

[0041] In this embodiment, by limiting the ratio of Al and Mn, the properties of the bridge steel can be improved. Specifically, when the Al / Mn ratio increases, the ferrite content increases; when the Al / Mn ratio decreases, the austenite content increases. In order to control the stability of the duplex structure, the element content ratio of the two needs to be controlled within 0.25 ≤ Al / Mn ≤ 0.4.

[0042] In some embodiments of the present invention, the following limiting conditions are satisfied:

[0043] 0.025% ≤ Nb + V + Ti ≤ 0.07%;

[0044] Wherein, Nb + V + Ti represents the sum of the mass percentages of Nb, V, and Ti.

[0045] In this embodiment, the addition of Nb, V, and Ti alloying elements can improve the strength, hardness, corrosion resistance, and heat treatment performance of steel. It should be noted that only sufficient amounts of Nb, V, and Ti elements can play a role in enhancing the performance of bridge steel. If the Nb, V, and Ti elements are below the range defined in the present invention, the enhancement effect is not obvious; however, when the content of these elements is too high (exceeding the range defined in the present invention), some adverse effects may also be caused. Cr can improve the corrosion resistance of materials. Excessive Nb content (exceeding the range defined in the present invention) may lead to an increase in the precipitation of NbC, affecting the plasticity and forgeability of the steel; excessive V content (exceeding the range defined in the present invention) will cause excessive precipitation of VC, affecting the toughness and plasticity of the steel and may reduce the processing performance; excessive Ti content (exceeding the range defined in the present invention) will cause excessive precipitation of TiC, reducing the toughness, weldability, and hot working performance of the steel. Therefore, in order to improve the strength of the steel while maintaining plasticity and toughness as well as good processing performance, it is necessary to control the content of Nb, V, and Ti within 0.025% ≤ Nb + V + Ti ≤ 0.07%.

[0046] In some embodiments of the present invention, the following limiting conditions are satisfied:

[0047] 1.3 ≤ 0.1M Sb + 0.6M Al + 0.05M Te + 0.3M Cr ≤ 4.5;

[0048] Wherein, M Sb 、M Al 、M Te 、M Cr are the mass percentages of Sb, Al, Te, and Cr, respectively.

[0049] In this embodiment, an appropriate Al content can form a dense and stable Al2O3 in the rust layer, thereby improving the protective effect of the rust layer. However, an excessive Al content (exceeding the range defined in the present invention) will lead to the precipitation of excessive AlN inclusions, increasing the probability of local corrosion. The Te element mainly improves the morphology of inclusions and enhances the pitting corrosion resistance of the steel. Excessive Te (exceeding the range defined in the present invention) may cause excessive precipitation phases, reducing the toughness; an appropriate amount of Sb element can produce stable Sb2O3 that is insoluble in acid, promoting the transformation of γ-FeOOH to Fe3O4, thereby enhancing the corrosion resistance. Excessive Sb (exceeding the range defined in the present invention) will interact with elements such as Cr and Ni in the steel, affecting their distribution and making it difficult to form a dense corrosion product film on the steel surface. In the present invention, when 1.3% ≤ 0.1Sb + 0.6Al + 0.05Te + 0.3Cr ≤ 4.5% is satisfied, the industrial atmospheric corrosion resistance of the steel is significantly improved.

[0050] In some embodiments of the present invention, the RE includes La and Ce.

[0051] In some embodiments of the present invention, the mass ratio of La to Ce is (4~6):(4~6).

[0052] In some embodiments of the present invention, the microstructure is ferrite, austenite, and lath martensite.

[0053] In a second aspect, embodiments of the present invention also provide a method for preparing a low-cost, high-strength, high-toughness, low-density, and corrosion-resistant bridge steel for preparing any of the above bridge steels. The preparation method includes:

[0054] Smelt each raw material using a vacuum induction furnace to obtain an ingot;

[0055] After forging the ingot, use a controlled rolling and controlled cooling process to obtain the bridge steel.

[0056] In the present invention, after forging, slow cooling (i.e., furnace cooling) is used for cooling, and then the rolling is carried out. The high-strength, high-toughness, low-density, and industrial-atmosphere-corrosion-resistant bridge steel prepared by the present invention, with its high strength, good toughness, lightweight, and corrosion resistance, is suitable for bridge construction in industrial atmosphere environments. It not only improves the durability and safety of the structure but also helps reduce the structural weight, can be used without painting, and reduces the maintenance cost.

[0057] In some embodiments of the present invention, the forging temperature of the ingot is 1100~1200°C, and the cooling method is slow cooling;

[0058] The controlled rolling and controlled cooling process includes: before rolling, the preheating temperature is controlled at 1200°C, the holding time is 2 h. After holding for 2 h, it is cooled in the furnace to 1000°C for rolling. The final rolling temperature is 870~890°C, rolling is carried out for 3 passes, the total reduction is 75%, and then it is water-cooled to about 450°C and then air-cooled to room temperature.

[0059] Performing a suitable controlled rolling and controlled cooling process is beneficial to obtaining lath martensite, which is also beneficial to improving the strength and toughness of the low-density weathering steel.

[0060] In the steel material prepared in this application, by increasing the contents of lightweight elements Al and Mn and compounding and adding microalloying elements such as Cr, Cu, and Sb, and through a controlled rolling and controlled cooling process, a steel material with a microstructure of ferrite, austenite, and lath martensite is obtained, thereby obtaining a high-strength, high-toughness, low-density, and industrial-atmosphere-corrosion-resistant bridge steel. This has important value in improving the comprehensive performance of engineering structures, extending the service life, and reducing the maintenance cost, and also lays a foundation for the development, production, and application of a new generation of weathering bridge steel.

[0061] To more clearly illustrate the technical solution and advantages of the present invention, the following describes in detail a low-cost, high-strength, low-density, corrosion-resistant bridge steel and its preparation method through several embodiments.

[0062] The performance test methods for the following embodiments and comparative examples are tensile tests, and the tensile rate is 10 −3 s −1 ; The corrosion resistance performance test specifically includes: electrochemical measurement in a 0.01M NaHSO3 solution and a 14-day immersion test to analyze the corrosion current, corrosion potential, and corrosion rate of the material to evaluate the corrosion resistance of the material.

[0063] Example 1

[0064] This embodiment provides a low-cost, high-strength, low-density, industrial-atmosphere-corrosion-resistant bridge steel, and the low-cost, high-strength, low-density, industrial-atmosphere-corrosion-resistant bridge steel contains the following components by mass percentage: C: 0.08%, Si: 0.31%, Mn: 13.88%, P≤0.01%, S≤0.01%, Ni: 0.28%, Cr: 0.49%, Mo: 0.28%, Al: 4.41%, Cu: 0.31%, Nb: 0.01%, V: 0.01%, Ti: 0.02%, RE: 0.004%, Te: 0.05%, Sb: 0.05%, and the rest are Fe and inevitable impurity elements; among them, rare earth RE is La and Ce, and the mass ratio of La to Ce is 6:4; Al / Mn = 0.32, Nb + V + Ti = 0.04%, 0.1M Sb +0.6M Al +0.05M Te +0.3M Cr =2.8%.

[0065] The microstructure of the high-strength, low-density, industrial-atmosphere-corrosion-resistant bridge steel consists of ferrite, austenite, and lath martensite. The SEM microstructure diagram of the high-strength, low-density, industrial-atmosphere-corrosion-resistant bridge steel in this embodiment.

[0066] In this embodiment, the preparation method of the low-cost, high-strength, low-density, industrial-atmosphere-corrosion-resistant bridge steel is as follows: Add the raw materials for preparing the low-cost, high-strength, low-density, industrial-atmosphere-corrosion-resistant bridge steel according to the above ratio into a vacuum induction furnace for smelting to obtain an ingot; the initial forging temperature for forging is 1150°C, and the cooling method is slow cooling; the preheating temperature for rolling is controlled at 1200°C, the holding time is 2h, it is cooled in the furnace to 1000°C for rolling, the final rolling temperature is about 880°C, it is rolled 3 passes, the reduction is 75%, after rolling, it is water-cooled to about 450°C, and then air-cooled to room temperature.

[0067] The yield strength of the product is 506.77 MPa, the tensile strength is 715.01 Mpa, the elongation is 56.3%, and the density is 7.41 g / cm 3 , the corrosion potential is -564.01 mV vs. SCE, and the corrosion current is 5.98 μA / cm 2 , the charge transfer resistance is 453.2 Ω·cm 2 , and the corrosion rate is 0.52 mm / a.

[0068] Example 2

[0069] This example provides a low-cost, high-strength, tough, low-density bridge steel resistant to industrial atmospheric corrosion. The mass percentages of the chemical components of the low-cost, high-strength, tough, low-density bridge steel resistant to industrial atmospheric corrosion are as follows: C: 0.08%, Si: 0.3%, Mn: 13.89%, P ≤ 0.01%, S ≤ 0.01%, Ni: 0.28%, Cr: 0.97%, Mo: 0.27%, Al: 4.61%, Cu: 0.31%, Nb: 0.01%, V: 0.01%, Ti: 0.03%, RE: 0.004%, Te: 0.1%, Sb: 0.1%, and the rest are Fe and inevitable impurity elements; among them, rare earth RE is La and Ce, and the mass ratio of La to Ce is 6:4; Al / Mn = 0.33, Nb + V + Ti = 0.05, 0.1M Sb + 0.6M Al + 0.05M Te + 0.3M Cr = 3.07%.

[0070] The microstructure of the low-cost, high-strength, tough, low-density bridge steel resistant to industrial atmospheric corrosion consists of ferrite, austenite, and lath martensite.

[0071] In this example, the preparation method of the low-cost, high-strength, tough, low-density bridge steel resistant to industrial atmospheric corrosion is as follows: Add the raw materials for preparing the low-cost, high-strength, tough, low-density bridge steel resistant to industrial atmospheric corrosion according to the above ratios into a vacuum induction furnace for smelting to obtain an ingot; the initial forging temperature for forging is 1150 °C, and the cooling method is slow cooling; the preheating temperature for rolling is controlled at 1200 °C, the holding time is 2 h, it is cooled with the furnace to 1000 °C for rolling, the final rolling temperature is about 880 °C, it is rolled for 3 passes, the reduction is 75%, after rolling, it is water-cooled to about 450 °C, and then air-cooled to room temperature.

[0072] The yield strength of the product is 512.34 MPa, the tensile strength is 688.45 Mpa, the elongation is 61.1%, and the density is 7.41 g / cm 3 , the corrosion potential is -476.65 mV vs. SCE, and the corrosion current is 3.74 μA / cm 2, the charge transfer resistance is 580.7 Ω·cm 2 , the corrosion rate is 0.4 mm / a.

[0073] Example 3

[0074] This example provides a low-cost, high-strength, low-density bridge steel resistant to industrial atmospheric corrosion. The mass percentages of the chemical components of the low-cost, high-strength, low-density bridge steel resistant to industrial atmospheric corrosion are as follows: C: 0.08%, Si: 0.3%, Mn: 13.77%, P ≤ 0.01%, S ≤ 0.01%, Ni: 0.7%, Cr: 0.97%, Mo: 0.27%, Al: 4.43%, Cu: 0.31%, Nb: 0.01%, V: 0.01%, Ti: 0.03%, RE: 0.005%, Te: 0.3%, Sb: 0.25%, and the rest are Fe and inevitable impurity elements. Among them, rare earth RE is La and Ce, the mass ratio of La to Ce is 6:4, Al / Mn = 0.32, Nb + V + Ti = 0.05, 0.1M Sb + 0.6M Al + 0.05M Te + 0.3M Cr = 2.99%.

[0075] The microstructure of the low-cost, high-strength, low-density bridge steel resistant to industrial atmospheric corrosion consists of ferrite, austenite and lath martensite.

[0076] In this example, the preparation method of the low-cost, high-strength, low-density bridge steel resistant to industrial atmospheric corrosion is as follows: Add the raw materials for preparing the low-cost, high-strength, low-density bridge steel resistant to industrial atmospheric corrosion according to the above ratios into a vacuum induction furnace for smelting to obtain an ingot; The initial forging temperature for forging is 1150 °C, and the cooling method is slow cooling; The preheating temperature for rolling is controlled at 1200 °C, the holding time is 2 h, it is cooled with the furnace to 1000 °C and then rolling starts, the final rolling temperature is 880 °C, rolling is carried out for 3 passes, the reduction is 75%, after rolling, it is water-cooled to 450 °C and then air-cooled to room temperature.

[0077] The yield strength of the obtained product is 496.85 MPa, the tensile strength is 656.67 Mpa, the elongation is 63.1%, and the density is 7.41 g / cm 3 , the corrosion potential is -450.32 mV vs. SCE, and the corrosion current is 4.37 μA / cm 2 , the charge transfer resistance is 655.9 Ω·cm 2 , the corrosion rate is 0.36 mm / a.

[0078] Comparative Example 1

[0079] Comparative Example 1 is basically the same as Example 1, except that the mass percentage of Mn is 8.14% and Al / Mn = 0.54;

[0080] The yield strength of the obtained product is 387.65 MPa, the tensile strength is 663.13 Mpa, the elongation is 50.1%, and the density is 7.42 g / cm 3 , the corrosion potential is -622.54 mV vs. SCE, and the corrosion current is 21.26 μA / cm 2 , the charge transfer resistance is 330.2 Ω·cm 2 , and the corrosion rate is 0.68 mm / a;

[0081] In summary, too little Mn content will cause a decrease in the strength of the product.

[0082] Comparative Example 2

[0083] Comparative Example 2 is basically the same as Example 1, except that the mass percentage of Mn is 23.73% and Al / Mn = 0.19;

[0084] The yield strength of the obtained product is 466.71 MPa, the tensile strength is 751.2 Mpa, the elongation is 30.2%, and the density is 7.42 g / cm 3 , the corrosion potential is -655.27 mV vs. SCE, and the corrosion current is 27.56 μA / cm 2 , the charge transfer resistance is 289.7 Ω·cm 2 , and the corrosion rate is 0.76 mm / a;

[0085] In summary, too much Mn content will cause a decrease in the plasticity of the product, an increase in MnS inclusions, and promote local corrosion.

[0086] Comparative Example 3

[0087] Comparative Example 3 is basically the same as Example 1, except that the mass percentage of Al is 1.74%, Al / Mn = 0.13, 0.1 M Sb +0.6 M Al +0.05 M Te +0.3 M Cr = 1.20%;

[0088] The yield strength of the obtained product is 388.21 MPa, the tensile strength is 816.44 Mpa, the elongation is 39.23%, and the density is 7.71 g / cm 3 , the corrosion potential is -648.50 mV vs. SCE, and the corrosion current is 28.63 μA / cm 2 , the charge transfer resistance is 263.4 Ω·cm 2 , and the corrosion rate is 0.8 mm / a;

[0089] In summary, if the Al content is too low, it will lead to a decrease in both the strength and plasticity of the product, a weakening of the passivation ability, and a reduction in corrosion resistance.

[0090] Comparative Example 4

[0091] Comparative Example 4 is basically the same as Example 1, except that the mass percentage of Al is 7.34%, Al / Mn = 0.53, 0.1M Sb +0.6M Al +0.05M Te +0.3M Cr =4.60%;

[0092] The yield strength of the obtained product is 546.47 MPa, the tensile strength is 763.25 Mpa, the elongation is 31.22%, and the density is 7.104 g / cm 3 , the corrosion potential is -551.22 mV vs. SCE, and the corrosion current is 18.77 μA / cm 2 , the charge transfer resistance is 342.7 Ω·cm 2 , and the corrosion rate is 0.66 mm / a;

[0093] In summary, if the Al content is too high, it will lead to an increase in AlN inclusions in the product, an increase in the risk of local corrosion, and a reduction in plasticity.

[0094] Comparative Example 5

[0095] Comparative Example 5 is basically the same as Example 1, except that Te is not added;

[0096] The yield strength of the obtained product is 496.47 MPa, the tensile strength is 696.23 Mpa, the elongation is 52%, and the density is 7.41 g / cm 3 , the corrosion potential is -462.3 mV vs. SCE, and the corrosion current is 10.3 μA / cm 2 , the charge transfer resistance is 389.4 Ω·cm 2 , and the corrosion rate is 0.57 mm / a;

[0097] In summary, without adding Te, it will lead to a decrease in the local corrosion resistance of the product and a slight decrease in strength and plasticity.

[0098] Comparative Example 6

[0099] Comparative Example 6 is basically the same as Example 1, except that Sb is not added;

[0100] The yield strength of the obtained product is 490.84 MPa, the tensile strength is 687.46 Mpa, the elongation is 58.7%, and the density is 7.41 g / cm 3, the corrosion potential is -587.25 mV vs. SCE, and the corrosion current is 7.85 μA / cm 2 , the charge transfer resistance is 416.3 Ω·cm 2 , the corrosion rate is 0.56 mm / a;

[0101] In summary, without adding Sb, the protective effect of the product rust layer will decrease, resulting in a decrease in corrosion resistance and a slight decrease in strength and plasticity.

[0102] Comparative Example 7

[0103] Comparative Example 7 is basically the same as Example 1, except that the mass percentage of Te is 0.44%;

[0104] The yield strength of the obtained product is 488.71 MPa, the tensile strength is 684.26 Mpa, the elongation is 50.2%, and the density is 7.41 g / cm 3 , the corrosion potential is -567.2 mV vs. SCE, and the corrosion current is 11.15 μA / cm 2 , the charge transfer resistance is 420.6 Ω·cm 2 , the corrosion rate is 0.56 mm / a;

[0105] In summary, too high Te content will lead to a decrease in the plasticity and corrosion resistance of the product.

[0106] Comparative Example 8

[0107] Comparative Example 8 is basically the same as Example 1, except that the mass percentage of Sb is 0.37%;

[0108] The yield strength of the obtained product is 521.3 MPa, the tensile strength is 708.4 Mpa, the elongation is 52.3%, and the density is 7.41 g / cm 3 , the corrosion potential is -570.25 mV vs. SCE, and the corrosion current is 7.05 μA / cm 2 , the charge transfer resistance is 420.8 Ω·cm 2 , the corrosion rate is 0.58 mm / a;

[0109] In summary, too high Sb content will lead to a decrease in the plasticity and corrosion resistance of the product.

[0110] Comparative Example 9

[0111] Comparative Example 9 is basically the same as Example 1, except that rare earth RE is not added;

[0112] The yield strength of the obtained product is 456.23 MPa, the tensile strength is 606.87 Mpa, the elongation is 48.2%, and the density is 7.41 g / cm 3, the corrosion potential is -580.42 mV vs. SCE, and the corrosion current is 12.88 μA / cm 2 , the charge transfer resistance is 389.2 Ω·cm 2 , the corrosion rate is 0.6 mm / a;

[0113] In summary, without adding rare earth RE, the ability of the product to resist local corrosion will decrease.

[0114] Comparative Example 10

[0115] Comparative Example 9 is basically the same as Example 1, except that the mass percentage of Nb is 0.005%, the mass percentage of V is 0.004%, the mass percentage of Ti is 0.012%, and Nb + V + Ti = 0.021%;

[0116] The yield strength of the obtained product is 587.43 MPa, the tensile strength is 800.25 Mpa, the elongation is 31%, and the density is 7.42 g / cm 3 , the corrosion potential is -570.33 mV vs. SCE, and the corrosion current is 7.21 μA / cm 2 , the charge transfer resistance is 421.1 Ω·cm 2 , the corrosion rate is 0.59 mm / a;

[0117] In summary, when Nb + V + Ti is less than 0.025%, the strength of the product increases, but the plasticity decreases, the processing performance is reduced, and the increase in the precipitation phase reduces the corrosion resistance.

[0118] Comparative Example 11

[0119] This comparative example provides a low-density weathering steel, and the mass percentages of the chemical components of the low-density weathering steel are: C: 0.09%; Si: 0.3%; Mn: 14.2%; P ≤ 0.01%; S ≤ 0.01%; Ni: 0.3%; Cr: 0.5%; Mo: 0.27%; Al: 2.4%; Cu: 0.31%; Nb: 0.01%; V: 0.01%; Ti: 0.03%, RE: 0.003%, and the rest are Fe and inevitable impurity elements; among them, the rare earth RE is La and Ce, and the mass ratio of La to Ce is 6:4; Al / Mn = 0.17, and Nb + V + Ti = 0.05%.

[0120] The microstructure of the low-density weathering steel consists of ferrite, austenite and lath martensite.

[0121] When preparing the high-strength and tough low-density weathering steel for industrial atmosphere corrosion of bridges in this comparative example, except for the raw material ratios, other parameters and operations are the same as those in Example 1.

[0122] The yield strength of the product is 391.34 MPa, the tensile strength is 956.66 Mpa, the elongation is 44.6%, and the density is 7.68 g / cm 3 , the corrosion potential is -631.15 mV vs. SCE, and the corrosion current is 23.26 μA / cm 2 , the charge transfer resistance is 313.6 Ω·cm 2 , and the corrosion rate is 0.7 mm / a.

[0123] Comparative Example 12

[0124] This comparative example provides a traditional weathering steel. The mass percentages of the chemical components of the traditional weathering steel are as follows: C: 0.08%; Si: 0.29%; Mn: 1.48%; P ≤ 0.01%; S ≤ 0.01%; Ni: 0.32%; Cr: 0.52%; Mo: 0.2%; Al: 0.02%; Cu: 0.32%; Nb: 0.01%; V: 0.01%; Ti: 0.02%, and the rest are Fe and inevitable impurity elements.

[0125] The microstructure of the traditional weathering steel consists of bainite.

[0126] When preparing the traditional weathering steel in this comparative example, except for the raw material ratios, other parameters and operations are the same as those in Example 1.

[0127] The yield strength of the product is 431.34 MPa, the tensile strength is 586.66 Mpa, the elongation is 22.6%, and the density is 7.85 g / cm 3 , the corrosion potential is -697.88 mV vs. SCE, and the corrosion current is 30.72 μA / cm 2 , the charge transfer resistance is 105.6 Ω·cm 2 , and the corrosion rate is 0.97 mm / a.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-cost, high-strength, low-density, corrosion-resistant bridge steel, characterized in that, The mass percentages of the chemical components of the bridge steel are as follows: C: 0.07% - 0.10%, Si: 0.25% - 0.35%, Mn: 13% - 15%, P ≤ 0.01%, S ≤ 0.01%, Ni: 0.25% - 0.70%, Cr: 0.4% - 1.0%, Mo: 0.2% - 0.8%, Al: 4% - 5%, Cu: 0.3% - 0.55%, Nb: 0.009% - 0.015%, V: 0.01% - 0.02%, Ti: 0.015% - 0.035%, RE: 0.003% - 0.006%, Te: 0.035% - 0.35%, Sb: 0.05% - 0.25%, and the balance is Fe and inevitable impurity elements; Satisfy the following limiting conditions: 0.27 ≤ Al / Mn ≤ 0.38; wherein, Al / Mn represents the mass ratio of Al and Mn; Satisfy the following limiting conditions: 0.034% ≤ Nb + V + Ti ≤ 0.07%; wherein, Nb + V + Ti represents the sum of the mass percentages of Nb, V and Ti; Satisfy the following limiting conditions: 2.8% ≤ 0.1M Sb + 0.6M Al + 0.05M Te + 0.3M Cr ≤ 3.3%; Among them, M Sb , M Al , M Te , M Cr are the mass percentages of Sb, Al, Te, and Cr, respectively.

2. The bridge steel according to claim 1, characterized in that, RE includes La and Ce.

3. The bridge steel according to claim 2, characterized in that, The mass ratio of La to Ce is (4 - 6):(4 - 6).

4. The bridge steel according to claim 1, wherein The microstructure is ferrite, austenite and lath martensite.

5. A preparation method of a low-cost, high-strength, high-toughness, low-density and corrosion-resistant bridge steel, characterized in that, For preparing the bridge steel according to any one of claims 1 - 4, the preparation method includes: Smelting each raw material by a vacuum induction furnace to obtain an ingot; After forging the ingot, adopting a controlled rolling and controlled cooling process to obtain the bridge steel.

6. The preparation method according to claim 5, characterized in that, The forging temperature of the ingot is 1100 - 1200 °C, and the cooling method is slow cooling; The controlled rolling and controlled cooling process includes: before rolling, the preheating temperature is controlled at 1200 °C, the holding time is 2 h. After holding for 2 h, it is cooled in the furnace to 1000 °C for rolling. The final rolling temperature is 870 - 890 °C, rolling is carried out for 3 passes, the total reduction is 75%. Subsequently, it is water - cooled to about 450 °C and then air - cooled to room temperature.

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