Low-carbon Cr-Cu-Al-Sn series high-corrosion-resistance steel and preparation method thereof

Abstract

The invention relates to low-carbon Cr-Cu-Al-Sn series high-corrosion-resistance steel and a preparation method thereof, and belongs to the technical field of steel for marine environment. The high corrosion-resisting steel comprises the following chemical components in percentage by weight: less than or equal to 0.15 percent of C, 0.5 to 1.0 percent of Cr, 0.1 to 0.3 percent of Cu, 0.4 to 2.0 percent of Al, 0.05 to 0.2 percent of Sn, less than or equal to 0.5 percent of Si, less than or equal to 1.2 percent of Mn, less than or equal to 0.10 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.005 percent of N, 0.0008 to 0.0015 percent of B, 0.010 to 0.025 percent of Ti and the balance of Fe and inevitable impurities. According to the corrosion-resistant steel and the preparation method thereof, the content of C is controlled to be kept at a low level, and elements such as Cr, Cu, Al and Sn are matched, so that the corrosion-resistant steel has high mechanical properties and excellent corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel for marine environment, and particularly relates to a low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel and a preparation method thereof. BACKGROUND

[0002] Steel structure marine platforms, building bridges infrastructure, construction and industrial machinery equipment in long-term service often need to be recoated to prolong the service life, and have higher requirements for reducing the whole life cycle cost. When used in a more serious corrosion environment, ordinary steel needs to be recoated every 20-30 years. When used in a high-humidity, high-salt and other serious corrosion environment, ordinary steel needs to be recoated again every 5-10 years, and the maintenance cost of recoating is high, and volatile organic compounds of the coating are not environmentally friendly. Especially the steel structure facilities across the sea and along the sea, since they are in a serious corrosion environment, it is extremely important to inhibit the corrosion degradation of the coating defect part.

[0003] At present, the weathering steels and corrosion-resistant steels for marine environment mainly include ultra-low-carbon bainite weathering steel, weathering steel Q345qDNH steel and the like, which cannot meet the service requirements in high-humidity, high-salt and other harsh environments. In order to meet the use requirements in high-humidity, high-salt environments, high-Cr, high-Ni and other elements are mainly used, for example, 3wt.% of Cr and 2wt.% of Ni. However, from the production cost, the prices of Cr and Ni elements are relatively expensive, and the production cost is high. In order to balance the production cost and corrosion resistance, the Q355 steel is widely used at present, which is matched with a coating, but the corrosion resistance effect is limited. SUMMARY

[0004] In view of the above analysis, the present application aims to provide a low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel and a preparation method thereof, to improve the corrosion resistance of the steel and balance the production cost.

[0005] In one aspect, the present application provides a low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel, and the chemical components thereof include, in terms of mass percentage, C≤0.15wt.%, Cr: 0.5~1.0wt.%, Cu: 0.1~0.3wt.%, Al: 0.4~2.0wt.%, Sn: 0.05~0.2wt.%, Si≤0.5wt.%, Mn≤1.2wt.%, P≤0.10wt.%, S≤0.005wt.%, N≤0.005wt.%, B: 0.0008~0.0015wt.%, Ti: 0.010~0.025wt.%, and the balance is Fe and inevitable impurities.

[0006] Further, the chemical composition of the corrosion-resistant steel includes C: 0.08-0.15 wt.%, Cr: 0.5-0.8 wt.%, Cu: 0.1-0.2 wt.%, Al: 0.8-2.0 wt.%, Sn: 0.1-0.2 wt.%, Si≤0.3 wt.%, Mn: 1.0-1.2 wt.%, P≤0.10 wt.%, S≤0.005 wt.%, N≤0.005 wt.%, B: 0.0008-0.0015 wt.%, Ti: 0.015-0.025 wt.%, and the balance of Fe and inevitable impurities.

[0007] Further, the chemical composition of the low-carbon Cr-Cu-Al-Sn high-corrosion-resistant steel further includes Nb: 0.05-0.10 wt.%, V: 0.02-0.15 wt.%.

[0008] Further, the microstructure of the low-carbon Cr-Cu-Al-Sn high-corrosion-resistant steel is ferrite and pearlite.

[0009] Further, the content of the ferrite is 75-90%, and the content of the pearlite is 10-25%.

[0010] Further, the low-carbon Cr-Cu-Al-Sn high-corrosion-resistant steel is resistant to marine atmospheric corrosion, and the average corrosion rate is 1.3259 g / m 2 ·h or less after 72 h of 3.5% NaCl immersion.

[0011] The low-carbon Cr-Cu-Al-Sn high-corrosion-resistant steel is resistant to seawater immersion corrosion, and the average corrosion rate is 0.7671 g / m 2 ·h or less after 72 h of 3.5% NaCl immersion.

[0012] Further, the low-carbon Cr-Cu-Al-Sn high-corrosion-resistant steel has a yield strength of ≥355 MPa, a yield strength ratio of ≤0.8, an elongation after fracture of ≥22%, and an impact energy at 0°C of ≥150 J.

[0013] In another aspect, the present application provides a preparation method of a low-carbon Cr-Cu-Al-Sn high-corrosion-resistant steel, which uses an electric furnace or converter smelting, LF+RH refining, continuous casting, heating, and controlled rolling and controlled cooling to prepare the high-corrosion-resistant steel.

[0014] Further, in the heating process, the heating temperature is 1130-1150°C.

[0015] Further, in the controlled rolling and controlled cooling process, the cumulative deformation amount is not less than 40%, the finish rolling temperature is not less than 900°C, and the water cooling is performed to 640-660°C after finish rolling, and then air cooling is performed to room temperature.

[0016] Compared with the prior art, the present application can achieve at least one of the following beneficial effects: 1. In the present application, the carbon content needs to be controlled to remain at a low level, and combined with elements such as Cr, Cu, Al and Sn, not only can the corrosion-resistant steel have high mechanical properties, but also has excellent corrosion resistance. The yield strength of the obtained low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel is ≥355 MPa, the yield strength ratio is ≤0.8, the elongation after fracture is ≥22%, and the impact energy at 0°C is ≥150 J. At the same time, under the same test conditions, the corrosion-resistant steel obtained by the present application has more than 1.7 times the corrosion resistance of Q355 steel in marine atmospheric corrosion and seawater immersion corrosion.

[0017] 2. Under the alloy composition system of the present application, not only can the corrosion resistance be improved, but also the high hardenability caused by the addition of Cr, Mn and other alloys can be reduced, thereby avoiding the presence of a large amount of bainite / martensite structure, reducing the yield strength ratio, and making the microstructure of the corrosion-resistant steel ferrite and pearlite, and the content of the ferrite is 75-90%, and the content of the pearlite is 10-25%.

[0018] 3. In the present application, Al, Sn and Cu elements are used to promote the formation of dense α-FeOOH phase in the rust layer, form a dense oxide film on the surface of the steel, block the erosion of chloride ions, and at the same time, improve the corrosion resistance of the steel. However, Sn is a low-melting-point element and is prone to segregation at the grain boundary, so a proper amount of B is added to reduce the segregation of Sn in the steel by using the grain boundary occupation effect of B. B is easy to combine with N in the steel, so a proper amount of Ti is further added to fix N in the steel, so that B is in a solid solution state and plays a grain boundary occupation effect.

[0019] The above technical solutions can be combined with each other in the present application to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purpose and other advantages of the present application can be achieved and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0021] Figure 1 The metallographic structure photo of the high corrosion-resistant steel obtained in Example 1; Figure 2 The metallographic structure photo of the high corrosion-resistant steel obtained in Example 2; Figure 3 The metallographic structure photo of the high corrosion-resistant steel obtained in Example 3; Figure 4A metallographic structure photo of the high corrosion-resistant steel obtained in Example 4; Figure 5 A metallographic structure photo of the high corrosion-resistant steel obtained in Example 5; Figure 6 A metallographic structure photo of the high corrosion-resistant steel obtained in Example 6; Figure 7 A metallographic structure photo of the low-alloy steel obtained in Comparative Example 1. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application, and together with the embodiments of the application illustrate the principles of the application. It is to be understood that the application is not limited to the embodiments disclosed but is applied to any embodiments within the scope of the application.

[0023] Steel structures of long-term service, marine platforms, building bridges infrastructure, construction and industrial machinery equipment often need to be recoated to extend the service life, and there is a higher requirement for reducing the life cycle cost. When used in a more severe corrosion environment, ordinary steel needs to be recoated every 20-30 years. When used in a high-humidity, high-temperature, high-salt, and other severe corrosion environments, ordinary steel needs to be recoated again every 5-10 years, and the maintenance cost of recoating is high, and volatile organic compounds of the coating are not environmentally friendly. In particular, steel structure facilities across the sea and along the coast are in a severe corrosion environment, and it is extremely important to inhibit the corrosion degradation of the coating defect site.

[0024] At present, weathering steels and corrosion-resistant steels for marine environments mainly include ultra-low-carbon bainite weathering steels, weathering steel Q345qDNH steels, and the like, which cannot meet the service requirements in harsh environments such as high humidity, high temperature, and high salt. In order to meet the use requirements in high humidity, high temperature, and high salt, elements such as high Cr and high Ni are mainly used, for example, 3wt.% of Cr and, for example, 2wt.% of Ni. However, from the production cost, the prices of Cr and Ni elements are relatively high, and the production cost is high. In order to balance the production cost and corrosion resistance, the Q355 steel is widely used at present, which is matched with a coating, but the corrosion resistance effect is limited.

[0025] Therefore, the present application provides a low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel, and the chemical components thereof include, in terms of mass percentage, C≤0.15wt.%, Cr: 0.5-1.0wt.%, Cu: 0.1-0.3wt.%, Al: 0.4-2.0wt.%, Sn: 0.05-0.2wt.%, Si≤0.5wt.%, Mn≤1.2wt.%, P≤0.10wt.%, S≤0.005wt.%, N≤0.005wt.%, B: 0.0008-0.0015wt.%, Ti: 0.010-0.025wt.%, and the balance is Fe and unavoidable impurities.

[0026] Compared with the prior art, in the present application, the C content needs to be controlled to keep a low level, and elements such as Cr, Cu, Al and Sn are further matched, so that the corrosion-resistant steel not only has high mechanical properties, but also has excellent corrosion resistance, the yield strength of the obtained low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel is ≥355 MPa, the yield strength ratio is ≤0.8, the elongation after fracture is ≥22%, and the impact energy at 0 ℃ is ≥150 J. Meanwhile, under the same test conditions, the corrosion-resistant steel obtained by the present application has more than 1.7 times the corrosion resistance of Q355B steel in marine atmospheric corrosion and seawater immersion corrosion.

[0027] The effects of each element are as follows: C: an effective solid solution strengthening element in steel, but in the present corrosion-resistant steel, too high a content of C will form more carbides, reducing the corrosion resistance and mechanical properties, and too high a content of C will also reduce the welding performance, so the content is controlled to be ≤0.15 wt.%.

[0028] Si: a strengthening element in steel, but too high a content of Si will reduce the elongation of the corrosion-resistant steel, so the content is comprehensively controlled to be ≤0.5 wt.%.

[0029] Mn: a stabilizing austenite element and a solid solution strengthening element, the steel of the present application is a low-carbon composition, and the Mn content is appropriately increased to ensure the strength, and the content is controlled to be ≤1.2 wt.%.

[0030] P: can improve the strength and also has an effective corrosion resistance, but it is severely segregated in the corrosion-resistant steel, thereby reducing the plasticity and toughness, so the content is comprehensively controlled to be ≤0.10 wt.%.

[0031] S: reduces the plasticity and toughness of the steel, and the MnS generated by S can act as a corrosion source, so the content is controlled to be ≤0.01 wt.% considering the high Mn content in the present corrosion-resistant steel.

[0032] Cr: an effective corrosion-resistant alloy element in steel and a ferrite-forming element, but too high a content of Cr will increase the hardenability and make it difficult to control the structure, and the content is controlled to be 0.5-1.0 wt.% considering the cost.

[0033] Al: a necessary deoxidizing element and also has good corrosion resistance, Al can increase the anodic reaction resistance, make the anodic reaction show weak passivation characteristics, mainly form a dense Al2O3 oxide film, enrich in the inner rust layer, have cation selectivity, and hinder the penetration of chloride ions into the rust layer. In the design of the present corrosion-resistant steel, Al can also play a role in reducing the hardenability and making it easy to control the structure, and the content is controlled to be 0.4-2.0 wt.%.

[0034] Sn: It can rapidly form SnO and SnO2 and promote the formation of α-FeOOH, which is beneficial to the densification and stabilization of the rust layer. Sn also has the effect of inhibiting local corrosion. In the design of the corrosion-resistant steel of this invention, Sn and Al are synergistically enriched in the inner rust layer, which can further improve the density of the rust layer. Both Al and Sn can rapidly enrich at the damaged parts of the anti-corrosion coating, forming a dense oxide film and a stable and dense rust layer, which hinders the rapid corrosion of the substrate. They can work synergistically with the anti-corrosion coating to extend the service life of the steel structure. The content of Sn in this invention is controlled at 0.05~0.20 wt.%.

[0035] B: It exists in steel in a solid solution state and preferentially segregates at grain boundaries. An appropriate amount of B has a grain boundary occupancy effect, which can reduce the segregation of low-melting-point element Sn at austenite grain boundaries. Excessive B leads to a decrease in steel toughness. In this invention, the content is controlled at 0.0008-0.0015 wt.

[0036] Ti: Combines with N to control and fix N, prevents B from forming BN, ensures that B is in a solid solution state, and plays a role in occupying grain boundaries. Excessive Ti will form liquid-precipitated TiN, which becomes a coarse inclusion and impairs toughness and corrosion resistance. If Ti is too low, it cannot fix N well, and it is difficult to prevent BN precipitation, thus failing to play the role of occupying B grain boundaries. In this invention, the content is controlled at 0.010~0.025 wt.%.

[0037] Cu: an effective corrosion-resistant element in steel, but excessive addition can lead to a decrease in plasticity and, in severe cases, even hot rolling cracking. This invention controls its content to 0.1~0.3 wt.%.

[0038] N: An effective solid solution strengthening element in steel. If the N content is too high, more Ti needs to be added for fixation, which can easily lead to the formation of large-sized TiN precipitates, reducing the toughness and pitting resistance of corrosion-resistant steel. Its content should be controlled below 0.005 wt.%.

[0039] This invention utilizes the synergistic effect of Al, Sn, and Cu elements to promote the formation of the dense α-FeOOH phase in the rust layer, forming a dense oxide film on the steel surface to inhibit chloride ion corrosion. Simultaneously, it increases the self-corrosion potential of the steel, improving its corrosion resistance. However, Sn, as a low-melting-point element, readily segregates at grain boundaries. Therefore, an appropriate amount of B is added to utilize its grain boundary occupancy effect, reducing Sn segregation in the steel. B readily combines with N in steel, requiring further addition of an appropriate amount of Ti to fix the N in the steel, keeping B in a solid solution state and allowing it to exert its grain boundary occupancy effect.

[0040] Preferably, the chemical composition, by mass percentage, includes C: 0.08~0.15 wt.%, Cr: 0.5~0.8 wt.%, Cu: 0.1~0.2 wt.%, Al: 0.8~2.0 wt.%, Sn: 0.1~0.2 wt.%, Si≤0.3 wt.%, Mn: 1.0~1.2 wt.%, P≤0.10 wt.%, S≤0.005 wt.%, N≤0.005 wt.%, B: 0.0008~0.0015 wt.%, Ti: 0.015~0.025 wt.%, with the balance being Fe and unavoidable impurities.

[0041] Specifically, the chemical composition of the low-carbon Cr-Cu-Al-Sn series high corrosion-resistant steel also includes Nb: 0.05~0.10wt.%, V: 0.02~0.15wt.%.

[0042] It should be noted that Nb / V are effective microalloying strengthening elements in steel, exhibiting precipitation strengthening, grain refinement strengthening, and dispersion strengthening effects. The addition of these two elements can effectively fix the carbon element; Nb precipitates in the austenite and ferrite regions, while V precipitates in large quantities in the ferrite region. The combined addition of these two elements can effectively prevent the precipitation of chromium carbides, thereby reducing Cr loss and improving the effect of localized corrosion. The target values ​​for this invention are: Nb: 0.05~0.10 wt.%, V: 0.02~0.15 wt.%.

[0043] Specifically, the microstructure of the low-carbon Cr-Cu-Al-Sn series high corrosion-resistant steel consists of ferrite and pearlite.

[0044] Preferably, the ferrite content is 75-90% and the pearlite content is 10-25%.

[0045] It should be noted that ferrite, as the "soft phase" in steel, can significantly improve the yield strength ratio of steel. Its content of more than 75% can ensure that the yield strength ratio of steel is below 0.80, and it has good seismic performance.

[0046] This invention provides a method for preparing low-carbon Cr-Cu-Al-Sn series high corrosion-resistant steel, which is prepared by electric furnace or converter smelting, LF+RH refining, continuous casting, heating and controlled rolling and cooling.

[0047] Specifically, during the heating process, the heating temperature is 1130~1150℃.

[0048] Specifically, during the controlled rolling and cooling process, the cumulative deformation per pass shall not be less than 40%, the final rolling temperature shall not be less than 900℃, and after final rolling, the temperature shall be water-cooled to 640~660℃ and then air-cooled to room temperature.

[0049] To more clearly describe the present invention, the following embodiments and comparative examples are provided for further illustration.

[0050] Examples 1-6 and Comparative Example 1 The preparation steps for 355MPa grade low-carbon Cr-Cu-Al-Sn corrosion-resistant steel are as follows: It is prepared using a process of vacuum induction furnace smelting → ingot casting → forging → controlled rolling and controlled cooling. After smelting and casting, ingots are obtained. After heating to 1130~1150℃ and holding for 1 hour, they are forged. The final forging temperature is not lower than 900℃, and the billet size is 60mm (thickness) × 100mm (width). After forging, the 60mm thick test steel is cut into a piece with a size of 60mm (thickness) × 60mm (width) × 100mm. It is heated to 1130~1150℃ and held for 1 hour. After being taken out of the furnace, the oxide scale is removed. It is rolled according to 60mm-48mm-39mm-31mm-24mm-18mm-15mm-12mm (positive tolerance). The finished product is about 1m long. The final rolling temperature is not lower than 900℃. After laminar cooling to 640~660℃, it is air-cooled to room temperature to obtain corrosion-resistant steel.

[0051] The chemical composition of the corrosion-resistant steels obtained in Examples 1-6 and Comparative Example 1 is shown in Table 1, and the parameter variations of the preparation method are shown in Table 2.

[0052] Table 1 Chemical composition (wt%) of the examples and comparative examples

[0053] In Table 1, " / " indicates that it is not added or does not contain.

[0054] Table 2 Specific hot rolling process parameters for the examples and comparative examples

[0055] The above embodiments and comparative examples were subjected to performance and microstructure tests. The mechanical property test results are shown in Table 3, and the microstructure test results are shown in Table 4.

[0056] Table 3 Mechanical properties of the examples and comparative examples

[0057] Table 4. Microstructure of Examples and Comparative Examples

[0058] Based on Examples 1-6 and Comparative Example 1, and referring to Tables 3 and 4, it can be seen that the microstructure of the low-carbon Cr-Cu-Al-Sn series high corrosion-resistant steel consists of ferrite and pearlite, with the ferrite content ranging from 75% to 90% and the pearlite content from 10% to 25%. The low-carbon Cr-Cu-Al-Sn series high corrosion-resistant steel exhibits a yield strength ≥355 MPa, a yield strength ratio ≤0.8, elongation after fracture A ≥22%, uniform elongation ≥15.0%, and impact energy at 0℃ ≥150 J.

[0059] Example 4 and Comparative Example 1 (Q355B) were selected to test corrosion resistance, and the results were evaluated using three different indoor accelerated corrosion tests. The results of the three indoor accelerated corrosion tests are shown in Table 5, and the corresponding test conditions are described below: The first method simulates marine atmospheric corrosion. The corresponding immersion corrosion conditions are as follows: solution: 3.5% NaCl solution; RH: 70±5%; test temperature: 25±2℃; each cycle: 60±3min, immersion time 12±1.5min; test period: 72h.

[0060] The second method simulates seawater corrosion, with the following full immersion corrosion conditions: solution: 3.5% NaCl solution; test temperature: 35℃; test period: 72 hours.

[0061] The third method involved a salt spray corrosion test on the coated steel. The corrosion conditions were as follows: solution: 5% NaCl solution, pH: 6.5-7.2; test temperature: 35℃. A 50μm layer of epoxy anti-rust primer was applied to the sample steel. The coated steel was then subjected to simulated salt spray tests for 2 hours, wetting for 2 hours, and drying for 4 hours, with each cycle lasting 8 hours. This process was repeated 72 times before measuring the thickness of the rust layer under the coating. The total test duration was 576 hours.

[0062] Three parallel samples were set up for each group of tests.

[0063] Table 5 Indoor corrosion accelerated test data

[0064] Table 6 Salt spray corrosion test data

[0065] As shown in Table 5, under the corrosive conditions of marine atmosphere and seawater corrosion, comparing the marine atmosphere and seawater corrosion resistance of Example 4 and Q355B, it can be seen that the addition of Al-Sn results in a higher corrosion potential of the experimental steel and a denser rust layer. The dense rust layer prevents the diffusion of chloride ions, so the corrosion resistance of Example 4 is better than that of Q355B. Specifically, the marine atmosphere corrosion resistance of Example 4 is more than 2.8 times that of Q355B, and the seawater corrosion resistance is more than 1.7 times that of Q355B.

[0066] Comparing the salt spray tests of the two groups of steel after coating, the synergistic effect of Al-Sn prevented the outward diffusion of ferrous ions after the coating was damaged, thus inhibiting the formation of rust. This is the reason why the rust layer in the example is thinner. As shown in Table 6, the corrosion resistance of Example 4 after coating is more than 2.3 times that of Q355B after coating.

[0067] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel, characterized by, The chemical composition includes C≤0.15wt.%, Cr: 0.5-1.0wt.%, Cu: 0.1-0.3wt.%, Al: 0.4-2.0wt.%, Sn: 0.05-0.2wt.%, Si≤0.5wt.%, Mn≤1.2wt.%, P≤0.10wt.%, S≤0.005wt.%, N≤0.005wt.%, B: 0.0008-0.0015wt.%, Ti: 0.010-0.025wt.%, the balance being Fe and inevitable impurities.

2. The low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel according to claim 1, characterized in that, The chemical composition includes C: 0.08-0.15wt.%, Cr: 0.5-0.8wt.%, Cu: 0.1-0.2wt.%, Al: 0.8-2.0wt.%, Sn: 0.1-0.2wt.%, Si≤0.3wt.%, Mn: 1.0-1.2wt.%, P≤0.10wt.%, S≤0.005wt.%, N≤0.005wt.%, B: 0.0008-0.0015wt.%, Ti: 0.015-0.025wt.%, the balance being Fe and inevitable impurities.

3. The low-carbon Cr-Cu-Al-Sn series high-corrosion-resistant steel according to claim 1 or 2, characterized in that, The chemical composition of the low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel further includes Nb: 0.05-0.10wt.%, V: 0.02-0.15wt.%.

4. The low-carbon Cr-Cu-Al-Sn series high-corrosion-resistant steel according to claim 1 or 2, characterized in that, The microstructure of the low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel is ferrite and pearlite.

5. The low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel according to claim 4, characterized in that, The content of the ferrite is 75-90%, and the content of the pearlite is 10-25%.

6. The low-carbon Cr-Cu-Al-Sn series high-corrosion-resistant steel according to claim 1 or 2, characterized in that, The low-carbon Cr-Cu-Al-Sn high-corrosion-resistant steel is resistant to marine atmospheric corrosion, 3.5% NaCl immersion, and the average corrosion rate is 1.3259 g / m 2 ·h or less; The low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel is resistant to seawater immersion corrosion, and the average corrosion rate in 3.5% NaCl immersion for 72h is 0.7671g / m 2 ·h or below.

7. The low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel according to claim 1, characterized in that, The yield strength of the low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel is ≥355MPa, the yield strength ratio is ≤0.8, the elongation after fracture is ≥22%, and the impact energy at 0℃ is ≥150J.

8. A method for producing a low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel according to any one of claims 1 to 7, characterized by, The high corrosion-resistant steel is prepared by the method of electric furnace or converter smelting, LF+RH refining, continuous casting, heating and controlled rolling and controlled cooling.

9. The method of claim 8, wherein the low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel is prepared by the steps of: preparing a molten steel by melting a raw material including Cr, Cu, Al, Sn, and Fe; and performing a vacuum refining treatment on the molten steel. In the heating process, the heating temperature is 1130-1150℃.

10. The method of claim 8, wherein the low-carbon Cr-Cu-Al-Sn high corrosion-resistant steel is prepared by the steps of: preparing a molten steel by melting a raw material including Cr, Cu, Al, Sn, and Fe; and casting the molten steel. In the controlled rolling and controlled cooling process, the cumulative deformation is not less than 40%, the finish rolling temperature is not less than 900℃, and the water cooling is performed to 640-660℃ after the finish rolling, and then air cooling is performed to room temperature.

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