Pitting corrosion resistant ferritic stainless steel and manufacturing method thereof

Abstract

The present invention discloses a pitting-resistant ferritic stainless steel and a manufacturing method thereof, relating to the technical field of stainless steel manufacturing. The chemical composition and weight percentage of the pitting-resistant ferritic stainless steel are as follows: C: ≤ 0.01, N: ≤ 0.05, Si: 0.50-1.50, Mn: 0.20-0.50, P: ≤ 0.040, S: ≤ 0.030, Cr: 16.0-19.0, Nb: 0.15-0.20, Ti: 1.50-2.50, with the remainder being Fe and unavoidable impurities. The present invention is suitable for the manufacture and application of pitting-resistant ferritic stainless steel.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel manufacturing, in particular to a pitting corrosion resistant ferritic stainless steel and a manufacturing method thereof. Background Art

[0002] For a long time, my country's ferritic stainless steel has been developing in the main directions of variety, high strength and toughness, easy welding, and pitting corrosion resistance in terms of design and manufacturing. Among them, the pitting corrosion resistance direction is mainly based on the idea of ​​increasing the chromium and molybdenum content, which easily leads to the precipitation of harmful phases.

[0003] Ferritic stainless steel primarily serves in atmospheric environments. Marine atmospheric environments contain corrosive factors such as chloride ions, water vapor, oxygen, and deicing agents, which can cause pitting corrosion, a serious threat to the service safety of ferritic stainless steel components. However, the corrosion resistance of existing ferritic stainless steels is insufficient to meet the requirements of harsh atmospheric environments. Therefore, there is an urgent need to develop a new type of pitting-resistant ferritic stainless steel to meet the needs of applications in these harsh atmospheric environments. Summary of the Invention

[0004] In view of this, an embodiment of the present invention provides a pitting corrosion resistant ferritic stainless steel and a manufacturing method thereof, which has good pitting corrosion resistance and can reduce costs.

[0005] In a first aspect, an embodiment of the present application provides a pitting corrosion resistant ferritic stainless steel, wherein the chemical composition and weight percentage of the steel are: C: ≤0.01, N: ≤0.05, Si: 0.50~1.50, Mn: 0.20~0.50, P: ≤0.040, S: ≤0.030, Cr: 16.0~19.0, Nb: 0.15~0.20, Ti: 1.50~2.50, and the rest is Fe and unavoidable impurities.

[0006] According to a specific implementation of the present invention, the microstructure of the ferritic stainless steel is ferrite, and a titanium-rich Laves phase is dispersed in the ferrite matrix.

[0007] According to a specific implementation of the present invention, titanium is distributed in the ferrite phase and between ferrite grains.

[0008] According to a specific implementation of the present invention, the weight percentage of Ti is 2.00% to 2.30%.

[0009] According to a specific implementation of the present invention, the weight percentage of Ti is 2.15% or 2.30%.

[0010] According to a specific implementation of the present invention, the chemical composition and weight percentage of the steel are: C: <0.008%, N: <0.005%, Mn: 0.33%, Si: 1.15%, P: <0.01%, S: <0.01%, Cr: 18.49%, Ti: 2.15%, Nb: 0.19%, and the rest are Fe and unavoidable impurities.

[0011] According to a specific implementation of the present invention, the chemical composition and weight percentage of the stainless steel are: C: 0.005%, N: 0.002%, Mn: 0.33%, Si: 1.15%, P: 0.005%, S: 0.005%, Cr: 18.49%, Ti: 2.15%, Nb: 0.19%, and the rest are Fe and unavoidable impurities.

[0012] In a second aspect, an embodiment of the present application provides a method for manufacturing pitting corrosion resistant ferritic stainless steel, comprising the following steps:

[0013] Smelting stainless steel molten steel, wherein the chemical composition and weight percentage of the steel are as follows: C:≤0.01, N:≤0.005, Si:0.50-1.50, Mn:0.20-0.50, P:≤0.040, S:≤0.030, Cr:16.0-19.0, Nb:0.15-0.20, Ti:1.50-2.50, and the remainder is Fe and unavoidable impurities;

[0014] The molten steel is cast to form an ingot, which is then heated to an austenitizing temperature of 900-1100°C and kept at this temperature for 30±1min to release the internal stress;

[0015] The starting rolling temperature is 1000-1200℃, followed by 8-10 rolling passes to form a 4mm±0.2mm steel plate, ensuring that the final rolling temperature is above 800℃;

[0016] The hot-rolled steel plate is placed in a muffle furnace at 600-900°C for 30±1 min, and then cooled to room temperature in air to obtain pitting corrosion-resistant ferritic stainless steel.

[0017] According to a specific implementation of the present invention, the weight percentage of Ti is 2.00% to 2.30%.

[0018] According to a specific implementation of the present invention, the weight percentage of Ti is 2.15% or 2.30%.

[0019] The present invention provides pitting corrosion-resistant ferritic stainless steel and a manufacturing method thereof. The invention adds 1.50% to 2.50% by weight of titanium to the ferritic stainless steel, thereby promoting the precipitation of a titanium-rich second phase in the ferritic stainless steel and facilitating the formation of a titanium-based passivation film on the surface of the ferritic stainless steel. The titanium-based passivation film, in combination with the chromium-based passivation film formed on the surface of the ferritic stainless steel, makes the passivation film on the surface of the ferritic stainless steel denser, more effectively hinders the penetration of chloride ions, and thus improves the pitting corrosion resistance of the ferritic stainless steel in an atmospheric environment.

[0020] Furthermore, titanium has a greater affinity for carbon than for chromium. When titanium is added to the steel in the above weight ratio, in addition to promoting the precipitation of the titanium-rich second phase in the ferritic stainless steel, part of the titanium will preferentially combine with carbon to form titanium carbide, which can effectively prevent the formation of chromium carbide to a certain extent, thereby increasing the chromium content in the ferrite phase, which can not only inhibit the initiation of pitting corrosion in the ferrite phase and improve the pitting corrosion resistance to meet the use requirements of ferritic stainless steel in atmospheric environment, but also improve the utilization rate of the chromium element added to the ferritic stainless steel and reduce the production cost of ferritic stainless steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the implementation methods or the description of the prior art. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1a Shown is a phase diagram of an embodiment of the present invention; Figure 1b Shown is a phase diagram of a comparative example;

[0023] Figure 1c Shown is the microscopic morphology of the embodiment;

[0024] Figure 1d Shown is the line scan result of the Laves phase in the embodiment;

[0025] Figure 2 Shown are potentiodynamic polarization curves of Examples and Comparative Examples;

[0026] Figure 3 Shown are the Motty-Schottky curves of Examples and Comparative Examples;

[0027] Figure 4a Shown are the XPS results of the examples; Figure 4b Shown are the XPS results of the comparative example;

[0028] Figure 5The element contents of the main phases in the examples and comparative examples were obtained by thermodynamic calculation. DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present application in detail with reference to the accompanying drawings. It should be understood that the embodiments described are only a portion of the embodiments of the present application, and not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] An embodiment of the present invention provides a pitting corrosion-resistant ferritic stainless steel, wherein the chemical composition and weight percentage of the steel are: C: ≤0.01, N: ≤0.05, Si: 0.50-1.50, Mn: 0.20-0.50, P: ≤0.040, S: ≤0.030, Cr: 16.0-19.0, Nb: 0.15-0.20, Ti: 1.50-2.50, and the rest is Fe and unavoidable impurities.

[0031] The content of the main alloying elements in the embodiment of the present invention is based on the following principles:

[0032] Impact of Carbon: Carbon is an essential element in steel. Increasing the carbon content in ferritic stainless steel degrades the steel's weldability and intergranular corrosion resistance. Therefore, the present invention utilizes an ultra-low carbon design, where carbon forms carbides with the alloying elements titanium and niobium to reduce the amount of dissolved carbon in the steel. In this embodiment, the carbon content is set to ≤ 0.01%.

[0033] Effect of Si: Si has little effect on the pitting corrosion resistance of stainless steel, but too high a Si content will reduce toughness and weldability. Therefore, in the embodiment of the present invention, the Si content is set at 0.50% to 1.50%.

[0034] Influence of Mn: Mn is harmful to the pitting corrosion resistance of stainless steel. Too high Mn content can also cause element segregation. Therefore, in the embodiment of the present invention, the Mn content is set at 0.20% to 0.50%.

[0035] Effect of Cr: Cr can effectively improve the pitting corrosion resistance of stainless steel. However, an increase in Cr content will also increase the tendency of stainless steel to precipitate harmful phases, increasing the difficulty of hot working. Therefore, in the embodiment of the present invention, the Cr content is set at 16% to 19%.

[0036] Effect of Nb: Nb can effectively replace C in stainless steel, reduce the tendency of intergranular corrosion, and NbC precipitation can increase grain nucleation sites, achieving the effect of grain refinement. However, the cost of Nb is relatively high. Taking all factors into consideration, the Nb content in the embodiment of the present invention is set at 0.15% to 0.20%.

[0037] The impact of Ti: Ti improves the pitting corrosion resistance of stainless steel. Ti improves the chromium passivation film, making it denser and hindering chloride ion penetration. Ti also promotes the precipitation of a titanium-rich second phase in ferritic stainless steel. The present invention proposes a Ti-containing ferritic stainless steel with a Ti content of 1.50% to 2.50%.

[0038] In addition, excessive P and S will cause segregation and inclusions, so it is necessary to control the P and S in the steel as low as possible. Therefore, the P and S contents in the embodiment of the present invention are controlled at P: ≤ 0.04%, S:

[0039] ≤0.03%.

[0040] The pitting corrosion-resistant ferritic stainless steel of the present invention adds 1.50% to 2.50% titanium by weight to the ferritic stainless steel, which can promote the precipitation of a titanium-rich second phase in the ferritic stainless steel, facilitate the formation of a titanium-based passivation film on the surface of the ferritic stainless steel, and cooperate with the chromium-based passivation film formed on the surface of the ferritic stainless steel to make the passivation film on the surface of the ferritic stainless steel denser, thereby improving the pitting corrosion resistance of the ferritic stainless steel in atmospheric environments. When the titanium content is less than 1.50%, the improvement in the pitting corrosion resistance of the ferritic stainless steel is limited and cannot meet the requirements of the atmospheric service environment. When the titanium content is higher than 2.50%, the hot working performance of the steel will be deteriorated. Therefore, the titanium content is set to 1.50-2.50% in this study.

[0041] Furthermore, titanium has a greater affinity for carbon than for chromium. When titanium is added to the steel in the above weight ratio, in addition to promoting the precipitation of the titanium-rich second phase in the ferritic stainless steel, part of the titanium will preferentially combine with carbon to form titanium carbide, which can effectively prevent the formation of chromium carbide to a certain extent, thereby increasing the chromium content in the ferrite phase. This not only inhibits the initiation of pitting corrosion in the ferrite phase and improves the pitting corrosion resistance to meet the use requirements of ferritic stainless steel in atmospheric environments, but also improves the utilization rate of the chromium added to the ferritic stainless steel, reduces the production cost of ferritic stainless steel, and effectively balances the use of chromium to improve the pitting corrosion resistance of stainless steel and the tendency of excessive chromium to cause the precipitation of harmful phases in stainless steel.

[0042] In some embodiments, the microstructure of the ferritic stainless steel is ferrite, with a titanium-rich second phase dispersed in the ferrite matrix. In one example, the titanium-rich second phase is a titanium-rich Laves phase.

[0043] In some embodiments, titanium is distributed in the ferrite phase and between ferrite grains. The distribution of titanium in the ferrite phase can inhibit the initiation of pitting corrosion in the ferrite phase and improve pitting corrosion resistance. The distribution of titanium between ferrite grains can reduce intergranular corrosion.

[0044] In order to obtain good pitting corrosion resistance, in some embodiments, the weight percentage of Ti is 2.00% to 2.30%. The pitting corrosion resistance of the ferritic stainless steel obtained according to this weight percentage of Ti is between that of 304 stainless steel and 316L stainless steel.

[0045] In one example, the weight percentage of Ti is 2.15%. In another example, the weight percentage of Ti is 2.30%.

[0046] In some embodiments, the chemical composition and weight percentage of the steel are: C: <0.008%, N: <0.005%, Mn: 0.33%, Si: 1.15%, P: <0.01%, S: <0.01%, Cr: 18.49%, Ti: 2.15%, Nb: 0.19%, and the rest is Fe and unavoidable impurities.

[0047] In some embodiments, the chemical composition and weight percentage of the stainless steel are: C: 0.005%, N: 0.002%, Mn: 0.33%, Si: 1.15%, P: 0.005%, S: 0.005%, Cr: 18.49%, Ti: 2.15%, Nb: 0.19%, and the rest is Fe and unavoidable impurities.

[0048] The present invention also provides a method for manufacturing pitting corrosion resistant ferritic stainless steel, comprising the following steps:

[0049] S11. Smelting molten stainless steel, wherein the chemical composition and weight percentage of the steel are as follows: C: ≤ 0.01, N: ≤ 0.005, Si: 0.50-1.50, Mn: 0.20-0.50, P: ≤ 0.040, S: ≤ 0.030, Cr: 16.0-19.0, Nb: 0.15-0.20, Ti: 1.50-2.50, and the remainder is Fe and unavoidable impurities;

[0050] S12, casting the molten steel to form a steel ingot, heating the steel ingot to an austenitizing temperature of 900-1100° C., and keeping the temperature for 30±1 min to release internal stress;

[0051] S13, the starting rolling temperature is 1000-1200℃, and then after 8-10 rolling passes, it becomes a steel plate with a thickness of 4mm±0.2mm, and the final rolling temperature is ensured to be above 800℃;

[0052] S14. The hot-rolled steel plate is placed in a muffle furnace at 600-900° C. and kept warm for 30±1 min, and then cooled to room temperature in air to obtain pitting-resistant ferritic stainless steel.

[0053] The method for producing the pitting corrosion resistant ferritic stainless steel of this embodiment can be used to produce the pitting corrosion resistant ferritic stainless steel described in any of the aforementioned embodiments.

[0054] The method for manufacturing pitting corrosion-resistant ferritic stainless steel of the present invention adds 1.50% to 2.50% by weight of titanium to the ferritic stainless steel, thereby promoting the precipitation of a titanium-rich second phase in the ferritic stainless steel and facilitating the formation of a titanium-based passivation film on the surface of the ferritic stainless steel. The titanium-based passivation film, in combination with the chromium-based passivation film formed on the surface of the ferritic stainless steel, makes the passivation film on the surface of the ferritic stainless steel more compact, can more effectively hinder the penetration of chloride ions, and can further improve the pitting corrosion resistance of the ferritic stainless steel in an atmospheric environment.

[0055] Furthermore, titanium has a greater affinity for carbon than for chromium. When titanium is added to the steel in the above weight ratio, in addition to promoting the precipitation of the titanium-rich second phase in the ferritic stainless steel, part of the titanium will preferentially combine with carbon to form titanium carbide, which can effectively prevent the formation of chromium carbide to a certain extent, thereby increasing the chromium content in the ferrite phase. This not only inhibits the initiation of pitting corrosion in the ferrite phase and improves the pitting corrosion resistance to meet the use requirements of ferritic stainless steel in atmospheric environments, but also improves the utilization rate of the chromium added to the ferritic stainless steel, reduces the production cost of ferritic stainless steel, and effectively balances the use of chromium to improve the pitting corrosion resistance of stainless steel and the tendency of excessive chromium to cause the precipitation of harmful phases in stainless steel.

[0056] In order to obtain good pitting corrosion resistance, in some embodiments, the weight percentage of Ti is 2.00% to 2.30%. The pitting corrosion resistance of the ferritic stainless steel obtained according to this weight percentage of Ti is between that of 304 stainless steel and 316L stainless steel.

[0057] In one example, the weight percentage of Ti is 2.15%. In another example, the weight percentage of Ti is 2.30%.

[0058] The technical solution of the present invention is described below with specific examples.

[0059] Example 1

[0060] A pitting corrosion-resistant ferritic stainless steel, wherein the chemical composition and weight percentage of the steel are: C: 0.002, N: 0.01, Si: 0.50, Mn: 0.20, P: 0.010, S: 0.010, Cr: 16.0, Nb: 0.15, Ti: 1.50, and the remainder is Fe and unavoidable impurities.

[0061] The method for manufacturing ferritic stainless steel comprises the following steps:

[0062] The molten steel is cast to form an ingot, which is then heated to an austenitizing temperature of 1050°C and kept at that temperature for 30 minutes to release the internal stress;

[0063] The starting rolling temperature is 1050°C, and then after 8 to 10 rolling passes, it becomes a 4 mm steel plate, ensuring that the final rolling temperature is above 800°C. The hot-rolled steel plate is placed in an 800°C muffle furnace for 30 minutes and then cooled to room temperature in air to obtain the pitting corrosion-resistant ferritic stainless steel.

[0064] Example 2

[0065] A pitting corrosion-resistant ferritic stainless steel. The chemical composition and weight percentage of the steel are: C: 0.005, N: 0.025, Si: 0.80, Mn: 0.30, P: 0.020, S: 0.015, Cr: 17.0, Nb: 0.18, Ti: 2.00, and the rest are Fe and unavoidable impurities.

[0066] The method for manufacturing ferritic stainless steel comprises the following steps:

[0067] The molten steel is cast to form an ingot, which is then heated to an austenitizing temperature of 1050°C and kept at that temperature for 30 minutes to release the internal stress;

[0068] The starting rolling temperature is 1050°C, and then after 8 to 10 rolling passes, it becomes a 4 mm steel plate, ensuring that the final rolling temperature is above 800°C. The hot-rolled steel plate is placed in an 800°C muffle furnace for 30 minutes and then cooled to room temperature in air to obtain the pitting corrosion-resistant ferritic stainless steel.

[0069] Example 3

[0070] A pitting corrosion-resistant ferritic stainless steel. The chemical composition and weight percentage of the steel are: C: 0.01, N: 0.05, Si: 1.50, Mn: 0.50, P: 0.040, S: 0.030, Cr: 19.0, Nb: 0.20, Ti: 2.50, and the rest are Fe and unavoidable impurities.

[0071] The method for manufacturing ferritic stainless steel comprises the following steps:

[0072] The molten steel is cast to form an ingot, which is then heated to an austenitizing temperature of 1050°C and kept at that temperature for 30 minutes to release the internal stress;

[0073] The starting rolling temperature is 1050°C, and then after 8 to 10 rolling passes, it becomes a 4 mm steel plate, ensuring that the final rolling temperature is above 800°C. The hot-rolled steel plate is placed in an 800°C muffle furnace for 30 minutes and then cooled to room temperature in air to obtain the pitting corrosion-resistant ferritic stainless steel.

[0074] Example 4

[0075] A pitting corrosion-resistant ferritic stainless steel has the following chemical composition and weight percentages: C: <0.008%, N: <0.005%, Mn: 0.33%, Si: 1.15%, P: <0.01%, S: <0.01%, Cr: 18.49%, Ti: 2.15%, Nb: 0.19%, and the remainder being Fe and unavoidable impurities.

[0076] The method for manufacturing ferritic stainless steel comprises the following steps:

[0077] The molten steel is cast to form an ingot, which is then heated to an austenitizing temperature of 1050°C and kept at that temperature for 30 minutes to release the internal stress;

[0078] The starting rolling temperature is 1050°C, and then after 8 to 10 rolling passes, it becomes a 4 mm steel plate, ensuring that the final rolling temperature is above 800°C. The hot-rolled steel plate is placed in an 800°C muffle furnace for 30 minutes and then cooled to room temperature in air to obtain the pitting corrosion-resistant ferritic stainless steel.

[0079] Comparative Example

[0080] A ferritic stainless steel, the chemical composition and weight percentage of which are: C: <0.008%, N: <0.005%, Mn 0.34%, Si: 1.14%, P: <0.01%, S: <0.01%, Cr: 18.07%, Ti: 0.26%, Nb: 0.19%, and the rest being Fe and unavoidable impurities.

[0081] The method for manufacturing ferritic stainless steel comprises the following steps:

[0082] The molten steel is cast to form an ingot, which is then heated to an austenitizing temperature of 1050°C and kept at that temperature for 30 minutes to release the internal stress;

[0083] The starting rolling temperature is 1050°C, and then after 8 to 10 rolling passes, it becomes a 4 mm steel plate, ensuring that the final rolling temperature is above 800°C. The hot-rolled steel plate is placed in an 800°C muffle furnace for 30 minutes and then cooled to room temperature in air to obtain the pitting corrosion-resistant ferritic stainless steel.

[0084] The ferritic stainless steels prepared in Example 4 and the comparative example were subjected to microstructure testing. Specifically, the matrix structure was tested by electron backscatter diffraction. The measured matrix structure of the ferritic stainless steel is shown in FIG1 .

[0085] Potentiodynamic polarization tests were performed on the ferritic stainless steel obtained in Example 4 and the comparative example. Specific experimental parameters are shown in Table 1.

[0086] Table 1 Experimental parameters of potentiodynamic polarization test

[0087]

[0088] The corrosion solution used in the potentiodynamic polarization test simulates the marine atmospheric solution, and its chemical composition is shown in Table 2.

[0089] Table 2 Chemical composition of the corrosion solution in the potentiodynamic polarization test (g / L)

[0090]

[0091] The pitting corrosion resistance of the ferritic stainless steel of Example 4 and the comparative example was tested using the above parameters and solutions. The test results are as follows: Figure 2 As shown. Figure 2 It can be seen that Example 4 has a higher pitting potential than the comparative example, and the pitting potential of the comparative example is between that of 304 stainless steel and 316L stainless steel.

[0092] The ferritic stainless steel prepared in Example 4 and the comparative example was subjected to a Motty-Schottky test to clarify the defect density in the passivation film. The test solution is shown in Table 2, and the specific experimental parameters are shown in Table 3.

[0093] Table 3

[0094]

[0095] The defect density of the passivation film on the surface of the ferritic stainless steel obtained in Example 4 and the comparative example was tested, and the test results are as follows: Figure 3 As shown. Figure 3 It can be seen that the defect density in the passivation film of Example 4 is lower than that of the comparative example.

[0096] The X-ray photoelectron spectroscopy (XPS) test was performed on the surface passivation film of the ferritic stainless steel prepared in Example 4 and the comparative example. The specific experimental parameters are shown in Table 4.

[0097] Table 4 Experimental parameters of XPS test

[0098]

[0099] The composition of the passive film on the surface of the ferritic stainless steel of Example 4 and the comparative example was tested using the above parameters, and the test results are shown in Figure 4 and Table 5. As can be seen from Figure 4 and Table 5, the passive film of Example 4 contains TiO2 and Ti elemental substance compared with the comparative example, indicating that the addition of Ti optimizes the passive film of the ferritic stainless steel.

[0100] Table 5

[0101]

[0102] The above XPS test is aimed at the improvement of the overall passivation film of the stainless steel surface by titanium. The embodiment of the present invention further performs thermodynamic simulation calculations on the alloy composition of the main phases in the comparative example and Example 4 at 800°C. The results are as follows: Figure 5 shown.

[0103] from Figure 5 It can be seen that the Laves phase in Example 4 is enriched with titanium, and the chromium content of the ferrite phase in Example 4 is 2% higher than that in the comparative example, indicating that the addition of titanium increases the chromium content of the ferrite phase, avoids the appearance of chromium-depleted areas, and ensures that Example 4 has better pitting corrosion resistance.

[0104] The above reference embodiments provide a detailed description of a pitting-resistant ferritic stainless steel and a method for manufacturing the same. These embodiments are illustrative rather than restrictive, and several embodiments may be cited within the defined scope. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention, which is subject to the claims.

Claims

1. A pitting corrosion resistant ferritic stainless steel, characterized in that: The chemical composition and weight percentage of the steel are as follows: C: ≤0.01, N: ≤0.005, Si: 0.50-1.50, Mn: 0.20-0.50, P: ≤0.040, S: ≤0.030, Cr: 16.0-19.0, Nb: 0.15-0.20, Ti: 1.50-2.50, and the remainder is Fe and unavoidable impurities. After the titanium element is added to the steel in the above weight ratio, the titanium preferentially combines with carbon to form titanium carbide to prevent the formation of chromium carbide; the titanium is distributed in the ferrite phase and between ferrite grains to inhibit the initiation of pitting corrosion in the ferrite phase; The method for manufacturing the steel comprises the following steps: Casting the molten steel with the chemical composition in the ratio to form a steel ingot, heating the steel ingot to an austenitizing temperature of 900-1100° C., and keeping the temperature for 30±1 min to release the internal stress; The starting rolling temperature is 1000-1200℃, followed by 8-10 rolling passes to form a 4mm±0.2mm steel plate, ensuring that the final rolling temperature is above 800℃; The hot-rolled steel plate is placed in a muffle furnace at 600-900° C. and kept warm for 30±1 min, and then cooled to room temperature in air to obtain pitting corrosion-resistant ferritic stainless steel.

2. The pitting corrosion resistant ferritic stainless steel according to claim 1, wherein: The microstructure of the ferritic stainless steel is ferrite, and titanium-rich Laves phase is dispersed in the ferrite matrix.

3. The pitting corrosion resistant ferritic stainless steel according to claim 1, wherein: The weight percentage of Ti is 2.00% to 2.30%.

4. The pitting corrosion resistant ferritic stainless steel according to claim 1, wherein: The weight percentage of Ti is 2.15% or 2.30%.

5. The pitting corrosion resistant ferritic stainless steel according to claim 1, wherein: The chemical composition and weight percentage of the steel are: C: <0.008%, N: <0.005%, Mn: 0.33%, Si: 1.15%, P: <0.01%, S: <0.01%, Cr: 18.49%, Ti: 2.15%, Nb: 0.19%, and the rest are Fe and unavoidable impurities.

6. The pitting corrosion resistant ferritic stainless steel according to claim 5, wherein: The chemical composition and weight percentage of the stainless steel are: C: 0.005%, N: 0.002%, Mn: 0.33%, Si: 1.15%, P: 0.005%, S: 0.005%, Cr: 18.49%, Ti: 2.15%, Nb: 0.19%, and the rest are Fe and unavoidable impurities.

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