Cr-Cu-Mo-Sb series high weathering resistant steel and preparation method thereof

Abstract

The invention relates to Cr-Cu-Mo-Sb series high weathering resistant steel and a preparation method thereof, belongs to the technical field of weathering resistant steel, and solves the problems of insufficient corrosion resistance and insufficient crevice corrosion resistance of Cr-Cu series weathering resistant steel in the prior art. The invention provides Cr-Cu-Mo-Sb series high weathering resistant steel. The Cr-Cu-Mo-Sb series high weathering resistant steel comprises the following components in percentage by mass: 0.055 to 0.080 percent of C, 0.23 to 0.50 percent of Si, 0.1 to 0.8 percent of Mn, 0.5 to 3.5 percent of Cr, 0.18 to 0.32 percent of Cu, 0.07 to 0.35 percent of Mo, 0.06 to 0.12 percent of Sb and the balance of Fe and inevitable impurities. The high-weathering-resistance steel is excellent in homogeneous corrosion resistance and crevice corrosion resistance, and excellent in obdurability matching; the yield strength ranges from 250 MPa to 440 MPa, the yield ratio ranges from 0.68 to 0.82, and the percentage elongation after fracture ranges from 20.5% to 31.0%.

Description

Technical Field

[0001] The invention relates to the technical field of weathering steel, and in particular to a Cr-Cu-Mo-Sb series high-weathering steel and a preparation method thereof. Background Art

[0002] Weathering steel is a low alloy steel with good atmospheric corrosion resistance. Cr, Cu and other alloying elements are commonly used in weathering steel. The addition of alloying elements such as Cr and Cu promotes the formation of a dense and highly adhesive protective film on the surface of the steel, thereby slowing down the corrosion of the steel. Cr-Cu weathering steel has been widely studied and gradually applied. The existing weathering steel has a relatively strong ability to resist uniform corrosion, but a weak ability to resist crevice corrosion. In actual use, it will cause serious corrosion in the structural gaps or surface gaps caused by other reasons, thereby affecting the overall stability or performance of the equipment or structure, and affecting the service life and safety performance of the steel. At present, the research on crevice corrosion-resistant weathering steel at home and abroad is still in its infancy, and the existing crevice corrosion-resistant weathering steel generally has expensive raw materials and high smelting difficulty, resulting in high overall economic costs. The comprehensive properties such as mechanical properties, uniform corrosion resistance, and crevice corrosion resistance are difficult to meet the application requirements in special scenarios, especially in harsh environments such as marine atmosphere. Summary of the invention

[0003] In view of the above analysis, an embodiment of the present invention aims to provide a Cr-Cu-Mo-Sb high weathering steel and a preparation method thereof, so as to solve at least one of the problems of existing weathering steels, such as insufficient crevice corrosion resistance, poor strength-toughness matching, expensive raw materials and great smelting difficulty.

[0004] The invention provides a Cr-Cu-Mo-Sb series high-weathering steel. The components in the high-weathering steel are calculated by mass percentage as follows: C: 0.055-0.080%, Si: 0.23-0.50%, Mn: 0.1-0.8%, Cr: 0.5-3.5%, Cu: 0.18-0.32%, Mo: 0.07-0.35%, Sb: 0.06-0.12%, and the balance is Fe and inevitable impurities.

[0005] Specifically, 0.5wt.%≤Cr<1.5wt.%, 0.15wt.%≤Mo+Sb<0.3wt.%, 0.9wt.%≤Mn+Cr≤1.9wt.%.

[0006] Specifically, the microstructure of the high weathering steel includes ferrite and pearlite, wherein the volume percentage of ferrite is 63% to 76%, and the volume percentage of pearlite is 24% to 37%.

[0007] Specifically, the yield strength of the high weathering steel is in the range of 250 to 360 MPa, the yield strength ratio is in the range of 0.76 to 0.82, and the elongation after fracture is in the range of 25.5 to 31.0%.

[0008] Specifically, 1.5wt.%≤Cr≤3.5wt.%, 0.3wt.%≤Mo+Sb≤0.45wt.%, 1.9wt.%≤Mn+Cr≤4.3wt.%.

[0009] Specifically, the microstructure of the high weathering steel includes ferrite, bainite and pearlite, wherein the volume percentage of ferrite is 62% to 71%, the volume percentage of bainite is 20% to 35%, and the rest is pearlite.

[0010] Specifically, the yield strength of the high weathering steel is in the range of 360-440 MPa, the yield strength ratio is in the range of 0.68-0.75, and the elongation after fracture is in the range of 20.5-25.0%.

[0011] Specifically, the high weathering steel is subjected to a crevice corrosion test according to GB / T 10127-2002, the corrosion solution is a FeCl3 solution, the corrosion time is 3 hours, and the corrosion depth at the crevice is 10 to 32 μm.

[0012] The present invention also discloses a method for preparing the high weathering steel, comprising the following steps: smelting, continuous casting, rolling, and cooling;

[0013] Among them, the heating temperature during the rolling process is 1150°C to 1250°C, the rolling passes are 4 to 6 times, the final rolling temperature is ≥850°C, and the thickness of the steel plate after the last rolling pass is 4 to 6 mm.

[0014] Furthermore, the cooling step is air cooling, and the cooling rate is 0.25-2°C / s.

[0015] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0016] 1. The high weathering steel provided by the present invention has good resistance to uniform corrosion and crevice corrosion.

[0017] In view of the demand for materials with high weather resistance and crevice corrosion resistance, the present invention proposes a low C+(Cr-Cu)+(Mo-Sb) alloy design. The low C design ensures good plastic toughness and low welding crack sensitivity; the Cr-Cu alloy design aims to form a dense oxide film such as Cr2O3 and Cu2O on the surface of the steel to ensure uniform corrosion performance of the steel. At the same time, considering the continuous increase in chloride ion concentration during the development of crevice corrosion, the risk of corrosion damage to steel increases, and the Cr in the rust layer 3+The possibility of ions hydrolyzing under the action of high chlorine increases, reducing the pH value of the corresponding area and accelerating the corrosion process. Therefore, Mo-Sb composite addition is designed. On the one hand, the addition of Mo and Sb generates dense oxides respectively, and jointly strengthens the surface protective film, making it denser and more stable, thereby effectively resisting the invasion of corrosive media; on the other hand, when Cu and Sb exist together, sufficient Sb can form a complex Cu2Sb with Cu, which is deposited on the steel surface, hindering the invasion of chloride ions, thereby further improving the crevice corrosion resistance. Therefore, (Cr-Cu) + (Mo-Sb) not only ensures uniform corrosion performance but also improves crevice corrosion resistance.

[0018] Anti-uniform corrosion performance: Refer to TB / T 2375-1993 Railway Weathering Steel Periodic Immersion Corrosion Test Method to carry out atmospheric environment uniform corrosion accelerated test. High weathering steel with a size of 60mm×40mm×3mm was periodically immersed in 0.01mol / L NaHSO3 solution. The experimental temperature was 45±2℃, one cycle was 60min, the immersion time was 12min, and the experimental period was 3 days and 7 days. After 3 days of corrosion, the corrosion rate of high weathering steel (Example 1) was 1.513g / m 2 ·h; after 7 days of corrosion, the corrosion rates were 1.131g / m 2 ·h. After 7 days, the corrosion morphology of high weathering steel is as follows Figure 1 shown.

[0019] Crevice corrosion resistance: Crevice corrosion test was carried out with reference to GB / T 10127-2002 "Stainless steel ferric chloride crevice corrosion test method", the corrosion solution was FeCl3 solution, and the corrosion time was 3h. The corrosion depth of the crevice of high weathering steel (Example 3) was relatively shallow, with a depth of 10-20μm.

[0020] 2. The high weathering steel provided by the present invention has a yield strength of 250-440 MPa, a yield strength ratio of 0.68-0.82, an elongation after fracture of 20.5-31.0%, and a microstructure mainly of ferrite, with a volume percentage of ferrite of 62%-76%, and the rest being pearlite or pearlite + bainite. It has excellent resistance to uniform corrosion and crevice corrosion, and a high degree of matching between strength and toughness. Compared with the existing crevice corrosion-resistant weathering steel, the comprehensive performance has been significantly improved, and can meet the use requirements under harsh conditions.

[0021] 3. The high weathering steel provided by the present invention has good matching of strength and toughness. The Cr-Cu-Mo-Sb weathering steel of the present invention achieves matching of mechanical properties of steels of different strength levels through alloy element matching and process design, thus meeting the material selection requirements of weathering steels of different strength levels.

[0022] When 0.5wt.%≤Cr<1.5wt.%, 0.15wt.%≤Mo+Sb<0.3wt.%, 0.9wt.%≤Mn+Cr≤1.9wt.%, the microstructure of the high weathering steel includes ferrite and pearlite, wherein the volume percentage of ferrite is 63%~76%, and the volume percentage of pearlite is 24%~37%; the yield strength range of the high weathering steel is 250~360MPa, the yield strength ratio range is 0.76~0.82, and the elongation after fracture is 25.5~31.0%.

[0023] When 1.5wt.%≤Cr≤3.5wt.%, 0.3wt.%≤Mo+Sb≤0.45wt.%, 1.9wt.%≤Mn+Cr≤4.3wt.%, the microstructure of the high weathering resistant steel includes ferrite, bainite and pearlite, wherein the volume percentage of ferrite is 62%~71%, the volume percentage of bainite is 20%~35%, and the rest is pearlite; the yield strength range of the high weathering resistant steel is 360~440MPa, the yield strength ratio range is 0.68~0.75, and the elongation after fracture is 20.5~25.0%.

[0024] 4. The alloy raw materials involved in the high weathering steel designed by the present invention are relatively cheap and easy to obtain, and the preparation process is simple and the conditions are mild. The existing equipment can meet the experimental needs. The smelting difficulty is significantly reduced compared with the existing crevice corrosion resistant weathering steel, and the economic cost is greatly reduced, which is suitable for large-scale production and wide application.

[0025] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0027] Figure 1 is the microstructure diagram of high weathering steel in Example 1;

[0028] Figure 2 is the microstructure diagram of high weathering steel in Example 2;

[0029] Figure 3 is the tensile curve of high weathering steel in Example 3;

[0030] Figure 4 is the microstructure diagram of high weathering steel in Example 4;

[0031] Figure 5 is the microstructure diagram of the alloy steel in Comparative Example 1;

[0032] Figure 6 It is a comparison chart of uniform corrosion rates of Example 1, Example 5 and Comparative Example 1;

[0033] Figure 7 This is the morphology near the crevice corrosion crevice of the high weathering steel sample in Example 3;

[0034] Figure 8 This is the morphology near the crevice corrosion crevice of the high weathering steel sample in Example 6;

[0035] Fig. 9 This is the morphology near the crevice corrosion crevice of the alloy steel sample in Comparative Example 2. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0037] The invention provides a Cr-Cu-Mo-Sb series high-weathering steel. The components in the high-weathering steel are calculated by mass percentage as follows: C: 0.055-0.080%, Si: 0.23-0.50%, Mn: 0.1-0.8%, Cr: 0.5-3.5%, Cu: 0.18-0.32%, Mo: 0.07-0.35%, Sb: 0.06-0.12%, and the balance is Fe and inevitable impurities.

[0038] Specifically, the effects / synergistic effects and contents of each component are determined as follows:

[0039] C: Carbon is one of the important elements that affect the strength, toughness, weldability and other properties of weathering steel. The low carbon content design ensures the high toughness and low welding crack sensitivity of weathering steel, and improves the service safety factor of steel. However, when the carbon content is lower than 0.05wt%, the smelting difficulty gradually increases, and the smelting cost increases. Therefore, the carbon content of the present invention is in the range of 0.055-0.080wt.%.

[0040] Si: Silicon is mainly used for deoxidation and to ensure the strength and hardness of steel. A proper amount of silicon can also improve the corrosion resistance of steel. The copper content of the present invention is in the range of 0.23 to 0.50 wt.%.

[0041] Mn: Manganese has deoxidation and desulfurization effects in steel, and can also improve the strength and toughness of steel. However, too high a manganese content is prone to defects such as macrosegregation and deteriorates the welding performance of weathering steel. The manganese content of the present invention is in the range of 0.1 to 0.8 wt.%.

[0042] Cr: After adding Cr to weathering steel, on the one hand, a dense Cr2O3 oxide film can be formed; on the other hand, the addition of Cr can form more stable products such as α-(Fe,Cr)OOH or FeCr2O4, which significantly improves the corrosion resistance of the steel. However, when the chromium content is too high, it will cause the deterioration of welding performance and increase the alloy cost. In addition, when the chromium content is too high, it is easy to hydrolyze in a chloride ion environment, which is not conducive to the improvement of crevice corrosion performance. The chromium content of the present invention ranges from 0.5 to 3.5wt.%, and is matched with Mo, Sb, etc. to synergistically improve the corrosion resistance.

[0043] Cu: Adding Cu to weathering steel is beneficial to the formation of dense oxide Cu2O or CuFeO2 on the surface of the steel, preventing the corrosive medium from further contacting the matrix. Therefore, the addition of copper can enhance the atmospheric corrosion resistance and crevice corrosion resistance of weathering steel. When the Cu content is too high, the surface of weathering steel is prone to "copper brittleness" defects, affecting its surface quality. The copper content of the present invention is in the range of 0.18 to 0.32 wt.%.

[0044] Mo: Mo is an important element for strengthening the corrosion resistance of steel, especially in an environment containing chloride ions, where it can effectively improve the weather resistance of steel. However, Mo is expensive, and adding more Mo significantly increases the cost of steel. The copper content of the present invention is in the range of 0.07 to 0.35 wt.%.

[0045] Sb: The addition of antimony can improve the corrosion resistance of steel. Antimony can form a protective Sb2O5 oxide film on the surface, reducing the corrosion rate of steel. In addition, the addition of antimony can synergize with the copper in the steel. Sufficient Sb can form a complex Cu2Sb with Cu and deposit on the surface of the steel, further improving the corrosion resistance. However, the addition of antimony will have an adverse effect on the welding performance and increase the tough-to-brittle transition temperature of the steel. In the present invention, the antimony content is controlled to be 0.06-0.12wt.%.

[0046] Synergistic effect: The purpose of Cr-Cu alloy design is to form a dense oxide film such as Cr2O3 and Cu2O on the surface of steel to ensure uniform corrosion resistance of steel. At the same time, considering the continuous increase in chloride ion concentration during the development of crevice corrosion, the risk of corrosion damage to steel increases and the Cr in the rust layer 3+The possibility of ions hydrolyzing under the action of high chlorine increases, reducing the pH value of the corresponding area and accelerating the corrosion process. Therefore, Mo-Sb composite addition is designed. On the one hand, the addition of Mo and Sb generates dense oxides respectively, and jointly strengthens the surface protective film, making it denser and more stable, thereby effectively resisting the invasion of corrosive media; on the other hand, when Cu and Sb exist together, sufficient Sb can form a complex Cu2Sb with Cu, which is deposited on the steel surface, hindering the invasion of chloride ions, thereby further improving the crevice corrosion resistance. Therefore, (Cr-Cu) + (Mo-Sb) not only ensures uniform corrosion performance but also improves crevice corrosion resistance.

[0047] In one possible design, 0.5wt.%≤Cr<1.5wt.%, 0.15wt.%≤Mo+Sb<0.3wt.%, 0.9wt.%≤Mn+Cr≤1.9wt.%.

[0048] Specifically, the microstructure of the high weathering steel includes ferrite and pearlite, wherein the volume percentage of ferrite is 63% to 76%, and the volume percentage of pearlite is 24% to 37%. The yield strength of the high weathering steel ranges from 250 to 360 MPa, the yield strength ratio ranges from 0.76 to 0.82, and the elongation after fracture is 25.5 to 31.0%.

[0049] It should be noted that when the corrosive medium in the service environment is weak, and the strength level requirements for steel are low and the plasticity requirements are high, considering the alloy cost, a lower Cr content design is selected, and a lower content of Mo+Sb and Mn+Cr is matched. From the perspective of corrosion resistance, the addition of Cr and Cu can ensure the uniform corrosion resistance in this environment; Mo and Sb are added in combination, and the addition of Mo and Sb respectively generates dense oxides, which jointly strengthen the surface protective film, making it denser and more stable, thereby effectively resisting the invasion of corrosive media. From the perspective of mechanical properties, both Mn and Cr elements improve the hardenability of steel. When the Mn and Cr contents are high, bainite with higher hardness is easily generated in the steel, resulting in increased strength but decreased plasticity. Therefore, lower Mn and Cr contents are selected to obtain a microstructure dominated by pearlite and ferrite, and obtain high elongation.

[0050] In another possible design, 1.5wt.%≤Cr≤3.5wt.%, 0.3wt.%≤Mo+Sb≤0.45wt.%, 1.9wt.%≤Mn+Cr≤4.3wt.%.

[0051] Specifically, the microstructure of the high weathering steel includes ferrite, bainite and pearlite, wherein the volume percentage of ferrite is 62% to 71%, the volume percentage of bainite is 20% to 35%, and the rest is pearlite. The yield strength of the high weathering steel ranges from 360 to 440 MPa, the yield strength ratio ranges from 0.68 to 0.75, and the elongation after fracture is 20.5 to 25.0%.

[0052] It should be noted that when the corrosive medium in the service environment is strong and the strength level of the steel is required to be high, the Cr content needs to be increased to improve the uniform corrosion resistance. When the Cr content increases, the risk of hydrolysis damage to the rust layer of weathering steel increases, which has an adverse effect on its crevice corrosion resistance. In order to compensate for the decrease in the stability of the rust layer, the Mo and Sb contents are appropriately increased. On the one hand, the addition of Mo and Sb can enhance the density and stability of the rust layer respectively; on the other hand, when the two elements Cu and Sb exist together, sufficient Sb can form a complex Cu2Sb with Cu, which is deposited on the steel surface, hindering chloride ion invasion, thereby further improving the crevice corrosion resistance. In addition, when the strength requirements of the steel are increased, the Mn+Cr content needs to be increased, and a bainite structure with higher hardness is obtained during the cooling process to room temperature after rolling.

[0053] Specifically, the high weathering steel is subjected to a crevice corrosion test according to GB / T 10127-2002, the corrosion solution is a FeCl3 solution, the corrosion time is 3 hours, and the corrosion depth at the crevice is 10 to 32 μm.

[0054] The present invention also discloses a method for preparing the high weathering steel, comprising the following steps: smelting, continuous casting, rolling, and cooling;

[0055] Among them, the heating temperature during the rolling process is 1150°C to 1250°C, the rolling passes are 4 to 6 times, the final rolling temperature is ≥850°C, and the thickness of the steel plate after the last rolling pass is 4 to 6 mm.

[0056] It should be noted that when the heating temperature is higher than 1250°C, the original austenite grain size will grow abnormally, the austenite grains will coarsen, and the performance of the weathering steel will deteriorate. When the heating temperature is lower than 1150°C, the temperature drops rapidly during the subsequent rolling process, which will cause the final rolling temperature to be lower than the design requirements. When the final rolling temperature is lower than 850°C, the weathering steel will deform after the phase change, and the plastic toughness of the steel will decrease. Similarly, the number of rolling passes should not be too many, otherwise the final rolling temperature will be lower than the design requirements.

[0057] Furthermore, the cooling step is air cooling, and the cooling rate is 0.25-2°C / s.

[0058] It should be noted that the thickness of the steel plate after the last rolling is relatively thin, at 4 to 6 mm. When air cooling is used, the cooling rate meets the requirements of organizational transformation, and the air cooling rate is slow, which is conducive to uniform cooling of different parts of the steel plate to ensure the uniformity of the microstructure, and the processing process is simple. When rapid cooling such as water cooling is used, higher requirements are placed on the cooling device.

[0059] Examples and Comparative Examples

[0060] The present invention adopts different composition ratios to design embodiments and comparative examples to illustrate the technical effects of the present invention. The specific ingredients of each embodiment and comparative example are shown in Table 1.

[0061] Table 1 Chemical composition of high weathering steel / alloy steel in various embodiments and comparative examples

[0062]

[0063] The preparation process includes smelting, continuous casting, rolling and cooling. The specific parameters are as follows:

[0064] Embodiment 1:

[0065] The ingot is smelted, the ingot is heated at 1200°C, the final rolling temperature is 887°C, and after 6 rolling passes, it is air-cooled to room temperature. The steel plate thickness is 4 mm; the cooling step is air cooling, and the cooling rate is 1.8°C / s.

[0066] Example 2: The ingot is smelted, the ingot is heated at 1250°C, the final rolling temperature is 889°C, and after rolling 4 times, it is air-cooled to room temperature. The steel plate thickness is 5 mm; the cooling step is air cooling, and the cooling rate is 1.3°C / s.

[0067] Example 3: The ingot is smelted, the ingot is heated at 1230°C, the final rolling temperature is 882°C, and after rolling 4 times, it is air-cooled to room temperature. The steel plate thickness is 6 mm; the cooling step is air cooling, and the cooling rate is 0.3°C / s.

[0068] Example 4: The ingot is smelted, the ingot is heated at 1150°C, the final rolling temperature is 882°C, and after rolling for 5 passes, it is air-cooled to room temperature. The steel plate thickness is 4 mm; the cooling step is air cooling, and the cooling rate is 1.5°C / s.

[0069] Example 5: The ingot is smelted, the ingot is heated at 1180°C, the final rolling temperature is 885°C, and after rolling 4 times, it is air-cooled to room temperature. The steel plate thickness is 5 mm; the cooling step is air cooling, and the cooling rate is 1.3°C / s.

[0070] Example 6: The ingot is smelted, the ingot is heated at 1160°C, the final rolling temperature is 889°C, and after rolling for 5 passes, it is air-cooled to room temperature. The steel plate thickness is 4 mm; the cooling step is air cooling, and the cooling rate is 1.5°C / s.

[0071] The preparation process and specific parameters of Comparative Example 1 are the same as those of Example 1; the preparation process and specific parameters of Comparative Example 2 are the same as those of Example 3.

[0072] The microstructure and mechanical properties of each embodiment and comparative example were characterized, and the results are shown in Table 2.

[0073] Table 2 Microstructure and mechanical properties of each embodiment and comparative example

[0074]

[0075]

[0076] For Example 1 and Comparative Example 1, an atmospheric environment uniform corrosion accelerated test was carried out with reference to TB / T 2375-1993 Railway Weathering Steel Periodic Immersion Corrosion Test Method:

[0077] The experimental steel with the size of 60mm×40mm×3mm was periodically immersed in 0.01mol / L NaHSO3 solution, the experimental temperature was 45±2℃, one cycle was 60min, the immersion time was 12min, and the experimental period was 3 days and 7 days. The corrosion comparison results of Example 1 and Comparative Example 1 are shown in Figure 6 After 3 days of corrosion, the corrosion rates of Example 1 and Comparative Example 1 were 1.513 g / m 2 h and 3.021g / m 2 ·h; After 7 days of corrosion, the corrosion rates of Example 1 and Comparative Example 1 were 1.131 g / m 2 h and 2.446g / m 2 h. The uniform corrosion resistance of the embodiment is better than that of the comparative example.

[0078] The crevice corrosion test was carried out on Example 3, Example 6 and Comparative Example 2 with reference to GB / T 10127-2002 "Stainless Steel Ferric Chloride Crevice Corrosion Test Method":

[0079] The corrosion solution is FeCl3 solution, and the corrosion time is 3h. The morphology and depth statistics of the corrosion pits near the crevice after crevice corrosion in Example 3, Example 6 and Comparative Example 2 are as follows: Figure 7 , Figure 8 and Fig. 9 The corrosion depth of the crevice of the samples of Example 3 and Example 6 is relatively shallow, with the depth of Example 3 being 10-20 μm and the depth of Example 6 being 23-32 μm. The corrosion of the crevice in Comparative Example 2 is relatively serious, with the crevice corrosion depth being 45-76 μm. The crevice corrosion resistance of the examples is better than that of the comparative examples.

[0080] To sum up, the high weathering steel has excellent uniform corrosion resistance and crevice corrosion resistance, and a high degree of strength-toughness matching; the yield strength is 250-440MPa, the yield strength ratio range is 0.68-0.82, and the elongation after fracture is 20.5-31.0%. Compared with the existing crevice corrosion-resistant weathering steel, the comprehensive performance has been significantly improved and can meet the use requirements under harsh conditions.

[0081] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A Cr-Cu-Mo-Sb high weathering steel, characterized in that: The components in the high weathering steel are calculated by mass percentage as follows: C: 0.055-0.080%, Si: 0.23-0.50%, Mn: 0.1-0.8%, Cr: 0.5-3.5%, Cu: 0.18-0.32%, Mo: 0.07-0.35%, Sb: 0.06-0.12%, and the remainder is Fe and unavoidable impurities.

2. The high weathering steel according to claim 1, characterized in that: Among them, 0.5wt.%≤Cr<1.5wt.%, 0.15wt.%≤Mo+Sb<0.3wt.%, 0.9wt.%≤Mn+Cr≤1.9wt.%.

3. The high weathering steel according to claim 2, characterized in that: The high weathering steel microstructure includes ferrite and pearlite, wherein the volume percentage of ferrite is 63% to 76%, and the volume percentage of pearlite is 24% to 37%.

4. The high weathering steel according to claim 2, characterized in that: The yield strength of the high weathering steel is in the range of 250-360 MPa, the yield strength ratio is in the range of 0.76-0.82, and the elongation after fracture is 25.5-31.0%.

5. The high weathering steel according to claim 1, characterized in that: Among them, 1.5wt.%≤Cr≤3.5wt.%, 0.3wt.%≤Mo+Sb≤0.45wt.%, 1.9wt.%≤Mn+Cr≤4.3wt.%.

6. The high weathering steel according to claim 5, characterized in that: The high weathering steel microstructure includes ferrite, bainite and pearlite, wherein the volume percentage of ferrite is 62% to 71%, the volume percentage of bainite is 20% to 35%, and the rest is pearlite.

7. The high weathering steel according to claim 5, characterized in that: The yield strength of the high weathering steel is in the range of 360-440 MPa, the yield strength ratio is in the range of 0.68-0.75, and the elongation after fracture is 20.5-25.0%.

8. The high weathering steel according to claim 1, characterized in that: The high weathering steel is subjected to a crevice corrosion test according to GB / T 10127-2002, the corrosion solution is a FeCl3 solution, the corrosion time is 3 hours, and the corrosion depth at the crevice is 10 to 32 μm.

9. A method for preparing the high weathering steel according to any one of claims 1 to 8, characterized in that: The following steps are involved: Smelting, continuous casting, rolling and cooling; Among them, the heating temperature during the rolling process is 1150°C to 1250°C, the rolling passes are 4 to 6 times, the final rolling temperature is ≥850°C, and the thickness of the steel plate after the last rolling pass is 4 to 6 mm.

10. The preparation method according to claim 9, characterized in that: The cooling step is air cooling, and the cooling rate is 0.25-2°C / s.

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