Ferritic stainless steel and application thereof, heat exchanger component and heat exchanger

Abstract

The invention provides ferritic stainless steel, application of the ferritic stainless steel, a heat exchanger component and a heat exchanger. The ferritic stainless steel comprises the following components in percentage by mass: 0 lt; c is less than or equal to 0.025%, 0lt; si < = 1.0%, 0lt; mn < = 1.0%, 0lt; p is less than or equal to 0.04%, 0lt; s < = 0.03%, 21% < = Cr < = 24%, 1.5% < = Mo < = 2.5%, 0 lt; n is smaller than or equal to 0.025%, 0.15% < = Nb < = 0.25%, 0.15% < = Ti < = 0.25%, and the balance Fe and inevitable impurities. The ferritic stainless steel provided by the invention has a high heat conductivity coefficient, a low expansion coefficient and excellent intergranular corrosion resistance, so that the ferritic stainless steel has excellent heat conductivity and fatigue resistance, and particularly, when the ferritic stainless steel is applied to a heat exchanger, the heat exchanger has excellent heat conductivity and longer service life, and the service life of the heat exchanger is prolonged. The ferritic stainless steel has excellent market application prospects, and particularly has great potential advantages in the application aspect of heat exchangers.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel materials, and particularly to a ferritic stainless steel, its application, a heat exchanger component and a heat exchanger. Background Art

[0002] The 2205 stainless steel material is applied to fields such as pressure vessels, high-pressure storage tanks, high-pressure pipelines, heat exchangers, etc. When applied in a heat exchanger, although the corrosion resistance of the 2205 stainless steel material can meet the requirements of the heat exchanger, the thermal conductivity and anti-fatigue performance of the 2205 stainless steel material are not good. For example, the heat exchanger tubes prepared from the 2205 material are prone to cracking due to fatigue, so it cannot fully meet the working conditions of the heat exchanger. In view of this, on the basis of the corrosion resistance of the 2205 stainless steel material, it is of great significance to improve the thermal conductivity and anti-fatigue performance of the material to meet the requirements of the heat exchanger working conditions. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the prior art. For this reason, an object of the present invention is to provide a ferritic stainless steel, its application, a heat exchanger component and a heat exchanger.

[0004] In a first aspect of the present invention, a ferritic stainless steel is provided. The ferritic stainless steel comprises the following components in mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 1.0%, 0 < Mn ≤ 1.***0%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 21% ≤ Cr ≤ 24%, 1.5% ≤ Mo ≤ 2.5%, 0 < N ≤ 0.025%, 0.15% ≤ Nb ≤ 0.25%, 0.15% ≤ Ti ≤ 0.25%, and the balance is Fe and unavoidable impurities.

[0005] According to the above ferritic stainless steel of the present invention, on the one hand, the Nb element forms a stable carbide NbC with the C element, refining the grains, and the Ti element forms Ti(C,N) with the C element and the N element. By the synergistic effect of the Nb element and the Ti element, the strength and intergranular corrosion resistance of the stainless steel material are improved. On the other hand, controlling the components of the stainless steel material within the above ranges, especially the manganese element, molybdenum element, nitrogen element, niobium element and titanium element within the above ranges, can significantly improve the thermal conductivity coefficient of the stainless steel material and reduce the thermal expansion coefficient of the material while ensuring the corrosion resistance of the stainless steel material, thereby improving the thermal conductivity and anti-fatigue performance of the material. Thus, the ferritic stainless steel has excellent thermal conductivity, anti-fatigue performance and corrosion resistance.

[0006] According to the above ferritic stainless steel of the present invention, preferably 0.4% ≤ Mn ≤ 0.8%.

[0007] For the ferritic stainless steel according to the present invention, preferably 2% ≤ Mo ≤ 2.3%.

[0008] For the ferritic stainless steel according to the present invention, preferably 0.18% ≤ Nb ≤ 0.22%.

[0009] For the ferritic stainless steel according to the present invention, preferably 0.18% ≤ Ti ≤ 0.22%.

[0010] For the ferritic stainless steel according to the present invention, preferably, it comprises the following components by mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 1.0%, 0.4% ≤ Mn ≤ 0.8%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 21% ≤ Cr ≤ 24%, 2% ≤ Mo ≤ 2.3%, 0 < N ≤ 0.025%, 0.18% ≤ Nb ≤ 0.22%, 0.18% ≤ Ti ≤ 0.22%, and the balance is Fe and unavoidable impurities.

[0011] For the ferritic stainless steel according to the present invention, within the range of 200°C - 1000°C, the thermal conductivity of the ferritic stainless steel is 21.4 W / (m·K) - 29.8 W / (m·K); For the ferritic stainless steel according to the present invention, within the range of 200°C - 1000°C, the coefficient of thermal expansion of the ferritic stainless steel is 11.1×(10^ -6 / °C) - 15.5×(10^ -6 / °C).

[0012] In the second aspect of the present invention, the present invention proposes the application of the above ferritic stainless steel in heat exchangers and electric heating tubes.

[0013] In the third aspect of the present invention, the present invention proposes a heat exchanger component. This heat exchanger component is prepared from the above ferritic stainless steel. Thus, this heat exchanger component has excellent corrosion resistance, a relatively high thermal conductivity, and a relatively low coefficient of thermal expansion.

[0014] In the fourth aspect of the present invention, the present invention proposes a heat exchanger. This heat exchanger includes the above heat exchanger component. Thus, this heat exchanger has good thermal conductivity and a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0016] Figure 1 is the equilibrium phase diagram of the ferritic stainless steel provided by the present invention; Figure 2 is the corrosion resistance test result diagram of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of the present invention; Figure 3 is the X-ray diffraction curve diagram of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of the present invention; Figure 4 is the tensile curve diagram of the ferritic stainless steel obtained in Example 1 of the present invention at different temperatures; Figure 5 is the evolution diagram of the room temperature tensile properties of the ferritic stainless steel obtained in Example 1 of the present invention after aging at 475°C; Figure 6 is the microstructure of the ferritic stainless steel obtained in Example 1 of the present invention after aging at 475°C for 40 h; Figure 7 is the EPR curve diagram of the straight seam welded pipe of the ferritic stainless steel obtained in Example 1 of the present invention; Figure 8 is the microstructure of the furnace brazing of the ferritic stainless steel obtained in Example 1 of the present invention; Figure 9 is the thermal conductivity curve diagram of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of the present invention; Figure 10 is the thermal expansion coefficient curve diagram of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of the present invention. Detailed implementation manners

[0017] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, 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 based on the embodiments in the present invention without making creative efforts fall within the protection scope of the present invention.

[0018] In the first aspect of the present invention, the present invention proposes a ferritic stainless steel. The ferritic stainless steel includes the following components in mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 1.0%, 0 < Mn ≤ 1.0%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 21% ≤ Cr ≤ 24%, 1.5% ≤ Mo ≤ 2.5%, 0 < N ≤ 0.025%, 0.15% ≤ Nb ≤ 0.25%, 0.15% ≤ Ti ≤ 0.25%, and the balance is Fe and unavoidable impurities.

[0019] For example, the C content is 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, etc., or any range between any two of the above values; the Si content is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 1.0%, etc., or any range between any two of the above values; the Mn content is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc., or any range between any two of the above values; the P content is 0.01%, 0.02%, 0.03%, 0.04%, etc., or any range between any two of the above values; the S content is 0.01%, 0.02%, 0.03%, etc., or any range between any two of the above values. The range between two values; Cr content is 21%, 22%, 23%, 24%, etc., or any range between two values ​​mentioned above; Mo content is 1.5%, 1.7%, 1.9%, 2.1%, 2.3%, 2.5%, etc., or any range between two values ​​mentioned above; N content is 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, etc., or any range between two values ​​mentioned above; Nb content is 0.15%, 0.17%, 0.19%, 0.21%, 0.23%, 0.25%, etc., or any range between two values ​​mentioned above; Ti content is 0.15%, 0.17%, 0.19%, 0.21%, 0.23%, 0.25%, etc., or any range between two values ​​mentioned above.

[0020] According to the ferritic stainless steel of the present invention, on the one hand, Nb and C elements form stable carbides NbC, refining the grains; Ti, C, and N elements form Ti(C,N), and through the synergistic effect of Nb and Ti elements, the strength and intergranular corrosion resistance of the stainless steel material are improved. On the other hand, by controlling the various components of the stainless steel material within the above-mentioned ranges, particularly manganese, molybdenum, nitrogen, niobium, and titanium, the thermal conductivity of the stainless steel material can be significantly improved and the coefficient of thermal expansion reduced while ensuring its corrosion resistance, thereby enhancing its thermal conductivity and fatigue resistance. Thus, the ferritic stainless steel possesses excellent thermal conductivity, fatigue resistance, and corrosion resistance. According to an embodiment of the present invention, the equilibrium phase diagram of the above-mentioned ferritic stainless steel is as follows: Figure 1 As shown, from Figure 1 It can be seen that the stainless steel in Example 1 has a ferritic structure before liquefaction and does not have an austenitic structure.

[0021] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.4% ≤ Mn ≤ 0.8%. By controlling the manganese content within the above range, the present invention can improve its corrosion resistance and increase the grain refinement of the ferritic stainless steel, thereby improving its plasticity and toughness.

[0022] According to embodiments of the present invention, the ferritic stainless steel preferably contains 2% ≤ Mo ≤ 2.3%. By controlling the molybdenum content within the above range, the present invention can improve its corrosion resistance, promote grain boundary strengthening of the ferritic stainless steel, refine its grains, and improve its plasticity and toughness.

[0023] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.18% ≤ Nb ≤ 0.22%. By controlling the niobium content within the above range, the present invention effectively allows Nb and C to form stable carbides NbC, refining the grain size and improving the material's strength and resistance to intergranular corrosion.

[0024] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.18% ≤ Ti ≤ 0.22%. By controlling the titanium content within the above range, the Ti element forms Ti(C,N), improving the material's strength and resistance to intergranular corrosion.

[0025] According to embodiments of the present invention, the above-mentioned ferritic stainless steel preferably contains 0.4% ≤ Mn ≤ 0.8% and 2% ≤ Mo ≤ 2.3%.

[0026] According to embodiments of the present invention, the above-mentioned ferritic stainless steel preferably contains 0.4% ≤ Mn ≤ 0.8% and 0.18% ≤ Nb ≤ 0.22%.

[0027] According to embodiments of the present invention, the above-mentioned ferritic stainless steel preferably contains 0.4% ≤ Mn ≤ 0.8% and 0.18% ≤ Ti ≤ 0.22%.

[0028] According to embodiments of the present invention, the above-mentioned ferritic stainless steel preferably contains 0.4%≤Mn≤0.8%, 2%≤Mo≤2.3%, and 0.18%≤Nb≤0.22%.

[0029] According to embodiments of the present invention, the above-mentioned ferritic stainless steel preferably has a content of 0.18%≤Nb≤0.22% and 0.18%≤Ti≤0.22%.

[0030] According to embodiments of the present invention, the above-mentioned ferritic stainless steel preferably contains 2%≤Mo≤2.3%, 0.18%≤Nb≤0.22%, and 0.18%≤Ti≤0.22%.

[0031] According to an embodiment of the present invention, the above ferritic stainless steel preferably comprises the following components in mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 1.0%, 0.4% ≤ Mn ≤ 0.8%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 21% ≤ Cr ≤ 24%, 2% ≤ Mo ≤ 2.3%, 0 < N ≤ 0.025%, 0.18% ≤ Nb ≤ 0.22%, 0.18% ≤ Ti ≤ 0.22%, and the balance is Fe and unavoidable impurities. By controlling the content of each component within the above range, the corrosion resistance, thermal conductivity, and fatigue resistance of the stainless steel material can be significantly improved.

[0032] According to an embodiment of the present invention, within the range of 200°C - 1000°C, the thermal conductivity of the above ferritic stainless steel is 21.4 W / (m·K) - 29.8 W / (m·K).

[0033] According to an embodiment of the present invention, within the range of 200°C - 1000°C, the thermal expansion coefficient of the above ferritic stainless steel is 11.1×(10^ -6 / °C) - 15.5×(10^ -6 / °C).

[0034] In the second aspect of the present invention, the present invention proposes the application of the above ferritic stainless steel in heat exchangers and electric heating tubes.

[0035] In the third aspect of the present invention, the present invention proposes a heat exchanger component. This heat exchanger component is prepared using the above ferritic stainless steel. Thus, this heat exchanger component has excellent corrosion resistance, a relatively high thermal conductivity, and a relatively low thermal expansion coefficient. It should be noted that the features and advantages described above for the ferritic stainless steel also apply to this heat exchanger component and will not be elaborated here.

[0036] According to an embodiment of the present invention, the heat exchanger component includes but is not limited to at least one of heat exchange tubes and heat exchange fins.

[0037] In the fourth aspect of the present invention, the present invention proposes a heat exchanger. This heat exchanger includes the above heat exchanger component. Thus, this heat exchanger has good thermal conductivity and a long service life. It should be noted that the features and advantages described above for the heat exchanger component also apply to this heat exchanger and will not be elaborated here.

[0038] For those not specifying specific techniques or conditions in the examples, follow the techniques or conditions described in the literature in this field or according to the product specifications. For reagents or instruments not indicating the manufacturer, they are all conventional products that can be obtained through regular channels.

[0039] Example 1 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.5%, Mn: 0.6%, P: 0.02%, S: 0.01%, Cr: 22%, Mo: 2.0%, N: 0.01%, Nb: 0.2%, Ti: 0.2%, balance Fe.

[0040] This embodiment also provides a method for preparing the above-mentioned ferritic stainless steel, including: 1. Raw material preparation: Prepare the required raw materials, such as iron, chromium, nickel, manganese, molybdenum, copper, etc., in a certain proportion.

[0041] 2. Mix evenly: Mix the raw materials, which can be done by mechanical mixing or dissolution mixing, to make them evenly mixed.

[0042] 3. Melting: The mixed raw materials are placed in a high-temperature furnace for melting and mixing.

[0043] 4. Casting: Pour the molten ferritic stainless steel liquid into a mold for casting to obtain ferritic stainless steel billet.

[0044] 5. Heat treatment: Heat treatment is performed on ferritic stainless steel billets to change their crystal structure and obtain the desired properties.

[0045] 6. Cold working: Ferritic stainless steel billets can be cold-worked by methods such as cold drawing, cold rolling, and cold stretching to form the required shape and size.

[0046] The final shape and size of the ferritic stainless steel material can be customized according to specific requirements, and can be in the form of plates, pipes, bars, wires, etc.

[0047] Example 2 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.5%, Mn: 0.4%, P: 0.02%, S: 0.02%, Cr: 22%, Mo: 2%, N: 0.01%, Nb: 0.18%, Ti: 0.18%, balance Fe.

[0048] The preparation method of ferritic stainless steel in this embodiment is the same as that in Example 1.

[0049] Example 3 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.5%, Mn: 0.8%, P: 0.03%, S: 0.02%, Cr: 22%, Mo: 2.3%, N: 0.02%, Nb: 0.22%, Ti: 0.22%, balance Fe.

[0050] The preparation method of ferritic stainless steel in this embodiment is the same as that in Example 1.

[0051] Example 4 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.1%, Mn: 0.05%, P: 0.01%, S: 0.01%, Cr: 21%, Mo: 1.5%, N: 0.01%, Nb: 0.15%, Ti: 0.15%, balance Fe.

[0052] The preparation method of ferritic stainless steel in this embodiment is the same as that in Example 1.

[0053] Example 5 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.025%, Si: 0.9%, Mn: 1.0%, P: 0.04%, S: 0.03%, Cr: 24%, Mo: 2.5%, N: 0.025%, Nb: 0.25%, Ti: 0.25%, balance Fe.

[0054] The method for preparing stainless steel in this embodiment is the same as that in Example 1.

[0055] Comparative Example 1 This comparative example provides a 2205 stainless steel material, which comprises the following components by weight percentage: C: 0.03%, Si: 1.0%, Mn: 2.0%, P: 0.04%, S: 0.03%, Cr: 22%, Ni: 6.0%, Mo: 3.0%, N: 0.2%, balance Fe.

[0056] The preparation method of the 2205 stainless steel in this comparative example is the same as that in Example 1.

[0057] Comparative Example 2 This comparative example provides a ferritic stainless steel that comprises, by weight percentage, the following components: C: 0.01%, Si: 0.5%, Mn: 0.5%, P: 0.02%, S: 0.02%, Cr: 22%, Mo: 1.3%, N: 0.01%, Nb: 0.1%, balance Fe.

[0058] The preparation method of the ferritic stainless steel in this comparative example is the same as that in Example 1.

[0059] Comparative Example 3 This comparative example provides a ferritic stainless steel that comprises, by weight percentage, the following components: C: 0.01%, Si: 0.5%, Mn: 1.2%, P: 0.02%, S: 0.02%, Cr: 22%, Mo: 3%, N: 0.03%, Nb: 0.3%, Ti: 0.3%, balance Fe.

[0060] The preparation method of the ferritic stainless steel in this comparative example is the same as that in Example 1.

[0061] Test case To verify the performance of the ferritic stainless steel provided by the present invention, further tests were conducted on the performance of the ferritic stainless steel prepared in each embodiment and comparative example.

[0062] (1) The corrosion resistance of the stainless steel materials of Example 1 and Comparative Example 1 was tested. The specific method is as follows: The corrosion resistance of the stainless steel materials of Example 1 and Comparative Example 1 was tested. The specific method is as follows: The potential dynamics of the pitting potential of stainless steel in 3.5% sodium chloride solution was measured according to GB / T 17899-2023. The experimental temperature was 65℃.

[0063] The corrosion resistance test results are shown below. Figure 2 .from Figure 2 It can be seen that the new stainless steel material in Example 1 has comparable corrosion resistance to that in Comparative Example 1.

[0064] (2) The X-ray diffraction curves of the stainless steel in Example 1 and Comparative Example 1 of the present invention are shown below. Figure 3 As shown, from Figure 3 It can be seen that, compared with Comparative Example 1, the stainless steel material of Example 1 exhibits a completely ferritic structure.

[0065] (3) The changes in high-temperature mechanical properties and mechanical properties after aging of the stainless steel in Example 1 are as follows: The tensile curves of stainless steel in Example 1 at different temperatures are as follows: Figure 4 As shown, from Figure 4 It can be seen that the tensile properties of Example 1 decrease uniformly with increasing temperature, while the strength and plasticity remain at a relatively high level.

[0066] Example 1: Evolution of room temperature tensile properties of stainless steel after aging at 475°C. Figure 5 As shown, from Figure 5 It can be seen that after aging at 475°C for different times, the tensile strength of Example 1 increased significantly, and the plasticity decreased but remained above 20%.

[0067] Figure 6 This is a microstructure diagram of Example 1 after aging. A large number of dispersed micron-sized precipitates can be observed, which have a significant strengthening effect on the material.

[0068] (4) The welding sensitization test of stainless steel in Example 1 is as follows: The sample is first immersed in 0.5M H2SO4 + 0.01M KSCN solution for 10 min. After the corrosion potential stabilizes, it is about -400mV (SCE). Then, the potential is scanned in the anodic direction at a potential scanning speed of 100mV / min to 300mV (SCE). It is held at this potential for 2 min. Then, the potential is scanned in the reverse direction at the same potential scanning speed to the corrosion potential. The maximum current of the two rings is measured. ia represents the maximum anodic polarization direction scanning current, ir is the maximum reactivation current, and the reactivation rate (ir / ia) is used to evaluate the intergranular corrosion sensitivity or sensitization degree of the material.

[0069] The EPR curves of stainless steel straight seam welded pipe samples from the weld zone and non-weld zone in Example 1 in a 0.5M H2SO4 + 0.01MKSCN solution at 30℃ are shown below. Figure 7 As shown, from Figure 7 It can be seen that the sensitization degree of the stainless steel straight seam welded pipe in Example 1 is extremely low in both the weld zone and the non-weld zone.

[0070] The results of the reflow welding of stainless steel in Example 1 are shown below. Figure 8 , Figure 8 It can be seen that the stainless steel in Example 1 welded well with the fin material under vacuum furnace, tunnel furnace and nickel-based and copper-based solder conditions, and no sensitization occurred.

[0071] (5) Thermal conductivity test The thermal conductivity of the stainless steel materials of the examples and comparative examples was determined in the range of 200℃-1000℃. The thermal conductivity of the stainless steel materials of the examples and comparative examples is shown in Table 1.

[0072] Table 1

[0073] Combination Figure 9 ,from Figure 9 It can be seen that the thermal conductivity of the stainless steel in Example 1 is significantly improved compared with that of the 2205 stainless steel in Comparative Example 1. The stainless steels in Examples 1-5 all have high thermal conductivity, indicating that the stainless steel of this application has excellent thermal conductivity.

[0074] (6) Fatigue resistance test The coefficient of thermal expansion of the stainless steel materials of the examples and comparative examples was determined in the range of 25℃-1000℃. The coefficients of thermal expansion of the stainless steel materials of the examples and comparative examples are shown in Table 2.

[0075] Table 2

[0076] Combination Figure 10 ,from Figure 10 It can be seen that the coefficient of thermal expansion of the stainless steel in Example 1 is 26% lower than that of the 2205 stainless steel in Comparative Example 1, and the stainless steels in Examples 1-5 all have low coefficients of thermal expansion, indicating that the stainless steel of this application has excellent fatigue resistance.

[0077] In summary, the ferritic stainless steel of this application not only has good corrosion resistance, but also excellent thermal conductivity and fatigue resistance.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ferritic stainless steel, characterized in that, Comprising the following components by mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 1.0%, 0 < Mn ≤ 1.0%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 21% ≤ Cr ≤ 24%, 1.5% ≤ Mo ≤ 2.5%, 0 < N ≤ 0.025%, 0.15% ≤ Nb ≤ 0.25%, 0.15% ≤ Ti ≤ 0.25%, the balance being Fe and unavoidable impurities.

2. The ferritic stainless steel according to claim 1, characterized in that, 0.4% ≤ Mn ≤ 0.8%.

3. The ferritic stainless steel according to claim 1, characterized in that, 2% ≤ Mo ≤ 2.3%.

4. The ferritic stainless steel according to claim 1, characterized in that, 0.18% ≤ Nb ≤ 0.22%.

5. The ferritic stainless steel according to claim 1, characterized in that, 0.18% ≤ Ti ≤ 0.22%.

6. The ferritic stainless steel according to any one of claims 1-5, characterized in that, Comprising the following components by mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 1.0%, 0.4% ≤ Mn ≤ 0.8%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 21% ≤ Cr ≤ 24%, 2% ≤ Mo ≤ 2.3%, 0 < N ≤ 0.025%, 0.18% ≤ Nb ≤ 0.22%, 0.18% ≤ Ti ≤ 0.22%, the balance being Fe and unavoidable impurities.

7. The ferritic stainless steel according to any one of claims 1-5, characterized in that, In the range of 200 °C - 1000 °C, the thermal conductivity of the ferritic stainless steel is 21.4 W / (m·K) - 29.8 W / (m·K); And / or, in the temperature range of 200℃-1000℃, the coefficient of thermal expansion of the ferritic stainless steel is 11.1×(10^ -6 / ℃)-15.5×(10^ -6 / ℃).

9. Use of the ferritic stainless steel according to any one of claims 1 - 7 in a heat exchanger, an electric heating tube.

9. A heat exchanger component, characterized in that, Prepared by using the ferritic stainless steel according to any one of claims 1 - 7.

10. A heat exchanger, characterized in that, Including the heat exchanger component according to claim 9.

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