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

Abstract

Provided in the present application are a ferritic stainless steel, the use thereof, a heat exchanger component and a heat exchanger. The ferritic stainless steel comprises the following components in percentage by mass: 0<C≤0.025%, 0<Si≤0.8%, 0<Mn≤1.0%, 0<P≤0.04%, 0<S≤0.03%, 17%≤Cr≤20%, 1.5%≤Mo≤2.5%, 0.5%≤Nb≤0.8% and 0<Ti≤0.02%, with the balance being Fe and inevitable impurities. The ferritic stainless steel provided in the present application has a high thermal conductivity and a low expansion coefficient, and exhibits excellent resistance to intergranular corrosion after sensitization and excellent resistance to chloride ion corrosion, thereby exhibiting excellent thermal conductivity and fatigue resistance; in addition, the ferritic stainless steel has low production costs. Especially when the ferritic stainless steel is applied to heat exchangers, the heat exchangers exhibit excellent thermal conductivity and a long service life. The ferritic stainless steel has an excellent market application prospect, and has great potential advantages especially in the use in heat exchangers.

Description

Ferritic Stainless Steel and Its Applications, Heat Exchanger Components, and Heat Exchangers

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to a Chinese patent application with application number 202411570803.0, titled "Ferritic Stainless Steel and Its Applications, Heat Exchanger Components, and Heat Exchangers", filed on November 04, 2024, which is incorporated herein by reference in its entirety. Technical Field

[0003] This application relates to the technical field of stainless steel materials, and particularly to a ferritic stainless steel and its applications, heat exchanger components, and heat exchangers. Background Art

[0004] Heat exchangers and the like are usually prepared using stainless steel materials. In heat exchanger products and equipment, chloride - containing liquids or tap water are generally used as cooling media for cooling purposes. However, the extremely corrosive environment generated by chlorides or chloride ions in tap water have a certain corrosive effect on stainless steel materials. In particular, intergranular corrosion constitutes a major problem in heat exchangers using chloride - containing liquids as coolants. Therefore, higher requirements are put forward for the corrosion resistance of the stainless steel materials used in heat exchangers. Summary of the Invention

[0005] This application proposes a ferritic stainless steel and its applications, heat exchanger components, and heat exchangers.

[0006] This application proposes a ferritic stainless steel. The ferritic stainless steel includes the following components by mass percentage:

[0007] 0 < C ≤ 0.025%, 0 < Si ≤ 0.8%, 0 < Mn ≤ 1.0%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 17% ≤ Cr ≤ 20%, 1.5% ≤ Mo ≤ 2.5%, 0.5% ≤ Nb ≤ 0.8%, 0 < Ti ≤ 0.02%, with the balance being Fe and unavoidable impurities.

[0008] According to the ferritic stainless steel of the present application, the Nb element forms a stable carbide NbC with C, which can refine the grains, improve the material strength and intergranular corrosion resistance, and the Nb element and the Cr element synergistically improve the pitting corrosion resistance of the material. Specifically, by controlling the Cr element content within the above range, the precipitation of the Cr-rich second phase can be effectively reduced, thereby improving the corrosion resistance, strength and toughness of the material. And by controlling the Nb element content within the above range, it can cooperate with the Cr element to significantly improve the pitting corrosion resistance, chloride ion corrosion resistance and sensitized intergranular corrosion resistance of the material. The inventors found that by adding niobium element and titanium element and controlling the components of the stainless steel material within the above range, especially, the manganese element, molybdenum element, niobium element and titanium element within the above range, the thermal conductivity of the stainless steel material can be significantly improved and the thermal expansion coefficient of the material can be reduced, thereby improving the thermal conductivity and anti-fatigue performance of the material. Thus, the ferritic stainless steel has excellent thermal conductivity, corrosion resistance and anti-fatigue performance, and the cost of the ferritic stainless steel is low.

[0009] In some embodiments, it is preferred that 0.05% ≤ Mn ≤ 0.2%.

[0010] In some embodiments, it is preferred that 2% ≤ Mo ≤ 2.5%.

[0011] In some embodiments, it is preferred that 0.6% ≤ Nb ≤ 0.7%.

[0012] In some embodiments, it is preferred that 0.005% ≤ Ti ≤ 0.015%.

[0013] In some embodiments, preferably, it comprises the following components by mass percentage:

[0014] 0 < C ≤ 0.025%, 0 < Si ≤ 0.8%, 0.05 ≤ Mn ≤ 0.2%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 17% ≤ Cr ≤ 20%, 2% ≤ Mo ≤ 2.5%, 0.6% ≤ Nb ≤ 0.7%, 0.005% ≤ Ti ≤ 0.015%, the balance being Fe and unavoidable impurities.

[0015] In some embodiments, within the range of 200°C - 1000°C, the thermal conductivity of the ferritic stainless steel is 23.0 W / (m·K) - 30.5 W / (m·K).

[0016] In some embodiments, within the range of 200°C - 1000°C, the thermal expansion coefficient of the ferritic stainless steel is 11.5×(l0^-6 / °C) - 14.5×(l0^-6 / °C).

[0017] The present application also proposes the application of the above ferritic stainless steel in heat exchangers and electric heating tubes.

[0018] This application also proposes a heat exchanger component. This heat exchanger component is made of the aforementioned ferritic stainless steel. Therefore, this heat exchanger component exhibits excellent corrosion resistance, high thermal conductivity, and low coefficient of thermal expansion.

[0019] This application also proposes a heat exchanger. This heat exchanger includes the aforementioned heat exchanger components. Therefore, this heat exchanger has good thermal conductivity and a long service life. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 is the equilibrium phase diagram of the ferritic stainless steel provided in this application;

[0022] Figure 2 shows the corrosion resistance test results of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of this application.

[0023] Figure 3 is an X-ray diffraction pattern of the ferritic stainless steel obtained in Example 1 and Comparative Example 1 of this application.

[0024] Figure 4 is a tensile curve of the ferritic stainless steel obtained in Example 1 of this application at different temperatures.

[0025] Figure 5 is a graph showing the evolution of room temperature tensile properties of the ferritic stainless steel obtained in Example 1 of this application after aging at 475°C.

[0026] Figure 6 shows the microstructure of the ferritic stainless steel obtained in Example 1 of this application after aging at 475°C for 40 hours.

[0027] Figure 7 is an EPR curve of the ferritic stainless steel straight seam welded pipe obtained in Example 1 of this application;

[0028] Figure 8 shows the brazing microstructure of ferritic stainless steel obtained in Example 1 of this application;

[0029] Figure 9 is a graph showing the thermal conductivity of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of this application.

[0030] Figure 10 is a graph showing the coefficient of thermal expansion of the ferritic stainless steel obtained in Example 1 and Comparative Example 1 of this application. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following will clearly and completely describe the technical solutions in this application in conjunction with the accompanying drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0032] 316L is a stainless steel material grade, mainly containing elements such as Cr, Ni, and Mo. 316L stainless steel is a molybdenum-containing stainless steel type. The material has a good surface gloss and excellent corrosion resistance. 316L stainless steel is widely used in the chemical industry, watch industry, 3C electronics industry, and is also commonly used in the heat exchanger manufacturing industry. Although 316L has certain corrosion resistance, it is prone to sensitization. If harsh coolants are used, its corrosion resistance still needs to be improved. At the same time, as a material used in heat exchangers, 316L has insufficient thermal conductivity and fatigue resistance, and a high cost.

[0033] Therefore, in order to meet the material properties in the field of heat exchangers, it is of great significance to develop materials with good corrosion resistance, thermal conductivity, and fatigue resistance.

[0034] This application proposes a ferritic stainless steel. The ferritic stainless steel includes the following components by mass percentage:

[0035] 0 < C ≤ 0.025%, 0 < Si ≤ 0.8%, 0 < Mn ≤ 1.0%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 17% ≤ Cr ≤ 20%, 1.5% ≤ Mo ≤ 2.5%, 0.5% ≤ Nb ≤ 0.8%, 0 < Ti ≤ 0.02%, with the balance being Fe and unavoidable impurities.

[0036] 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%, 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 range between the point values; S content is 0.01%, 0.02%, 0.03%, etc., or the range between any two of the above point values; Cr content is 17%, 18%, 19%, 20%, etc., or the range between any two of the above point values; Mo content is 1.5%, 1.7%, 1.9%, 2.1%, 2.3%, 2.5%, etc., or the range between any two of the above point values; Nb content is 0.5%, 0.6%, 0.7%, 0.8%, etc., or the range between any two of the above point values; Ti content is 0.005%, 0.01%, 0.015%, 0.02%, etc., or the range between any two of the above point values.

[0037] According to the ferritic stainless steel described in this application, Nb forms a stable carbide NbC with C, which can refine the grains, improve the material's strength and resistance to intergranular corrosion. Furthermore, Nb and Cr synergistically improve the material's resistance to pitting corrosion. Specifically, by controlling the Cr content within the aforementioned range, the precipitation of Cr-rich second phase can be effectively reduced, thereby improving the material's corrosion resistance, strength, and toughness. Controlling the Nb content within the aforementioned range can synergistically enhance the material's resistance to pitting corrosion, chloride ion corrosion, and sensitized intergranular corrosion. The inventors have discovered that by adding niobium and titanium and controlling the composition of the stainless steel material within the aforementioned ranges, particularly manganese, molybdenum, niobium, and titanium, the thermal conductivity of the ferritic stainless steel material can be significantly improved, and the coefficient of thermal expansion can be reduced, thereby enhancing the material's thermal conductivity and fatigue resistance. Therefore, this ferritic stainless steel possesses excellent thermal conductivity, corrosion resistance, and fatigue resistance, and is also low in cost.

[0038] According to the embodiments of this application, the equilibrium phase diagram of the above-mentioned ferritic stainless steel is shown in Figure 1. As can be seen from Figure 1, the stainless steel of Example 1 has a ferritic structure before liquefaction and does not have an austenitic structure.

[0039] In some embodiments, the ferritic stainless steel preferably contains 0.05% ≤ Mn ≤ 0.2%. Controlling the manganese content within the above range can improve its corrosion resistance and increase the grain refinement of the ferritic stainless steel, thereby enhancing its plasticity and toughness.

[0040] In some embodiments, the ferritic stainless steel preferably contains 2% ≤ Mo ≤ 2.5%. By controlling the molybdenum content within the above range, this application can improve its corrosion resistance, promote grain boundary strengthening of the ferritic stainless steel, refine its grains, and improve its plasticity and toughness.

[0041] In some embodiments, the ferritic stainless steel preferably contains 0.6% ≤ Nb ≤ 0.7%. This application controls the niobium content within the above range, allowing Nb to form stable NbC carbides with C, refining the grain size and improving material strength and resistance to intergranular corrosion. Adding more Nb can also increase the Cr content in the passivation film, thereby improving pitting corrosion resistance.

[0042] In some embodiments, the ferritic stainless steel described above preferably contains 0.005% ≤ Ti ≤ 0.015%. This application controls the titanium content within the above range so that the Ti element will form Ti(C,N), which improves the material strength and resistance to intergranular corrosion, while avoiding excessive Ti element forming TiN, thereby causing surface defects.

[0043] In some embodiments, the ferritic stainless steel described above preferably contains 0.05% ≤ Mn ≤ 0.2% and 2% ≤ Mo ≤ 2.5%.

[0044] In some embodiments, the ferritic stainless steel described above preferably contains 0.05% ≤ Mn ≤ 0.2%, 2% ≤ Mo ≤ 2.5%, and 0.6% ≤ Nb ≤ 0.7%.

[0045] In some embodiments, the ferritic stainless steel described above preferably contains 0.05% ≤ Mn ≤ 0.2%, 2% ≤ Mo ≤ 2.5%, and 0.005% ≤ Ti ≤ 0.015%.

[0046] In some embodiments, the ferritic stainless steel described above preferably contains 0.6% ≤ Nb ≤ 0.7% and 0.005% ≤ Ti ≤ 0.015%.

[0047] In some embodiments, the above-mentioned ferritic stainless steel preferably contains 2% ≤ Mo ≤ 2.5%, 0.6% ≤ Nb ≤ 0.7%, and 0.005% ≤ Ti ≤ 0.015%.

[0048] In some embodiments, the above ferritic stainless steel preferably comprises the following components in mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 0.8%, 0.05 ≤ Mn ≤ 0.2%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 17% ≤ Cr ≤ 20%, 2% ≤ Mo ≤ 2.5%, 0.6% ≤ Nb ≤ 0.7%, 0.005% ≤ Ti ≤ 0.015%, with the balance being Fe and unavoidable impurities. By controlling the content of each component within the above ranges, the corrosion resistance, thermal conductivity, and fatigue resistance of the stainless steel material can be significantly improved.

[0049] In some embodiments, within the range of 200°C - 1000°C, the thermal conductivity of the above ferritic stainless steel is 23.0 W / (m·K) - 30.5 W / (m·K).

[0050] In some embodiments, within the range of 200°C - 1000°C, the thermal expansion coefficient of the above ferritic stainless steel is 11.5×(10^-6 / °C) - 14.5×(10^-6 / °C).

[0051] This application also proposes the application of the above ferritic stainless steel in heat exchangers and electric heating tubes.

[0052] This application also 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.

[0053] In some embodiments, the heat exchanger component includes but is not limited to at least one of heat exchange tubes and heat exchange fins.

[0054] This application also 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.

[0055] For those technical or conditions not specified in the examples, they shall be in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through regular channels.

[0056] Example 1

[0057] This example provides a ferritic stainless steel which, in mass percentage, comprises the following components:

[0058] C: 0.01%, Si: 0.5%, Mn: 0.1%, P: 0.02%, S: 0.02%, Cr: 18%, Mo: 2.2%, Nb: 0.6%, Ti: 0.01%, balance Fe.

[0059] This embodiment also provides a method for preparing the above-mentioned ferritic stainless steel, including:

[0060] 1. Raw material preparation: Prepare the required raw materials, such as iron, chromium, nickel, manganese, molybdenum, copper, etc., in a certain proportion.

[0061] 2. Mix evenly: Mix the raw materials, which can be done by mechanical mixing or dissolution mixing, to make them evenly mixed.

[0062] 3. Melting: The mixed raw materials are placed in a high-temperature furnace for melting and mixing.

[0063] 4. Casting: Pour the molten ferritic stainless steel liquid into a mold for casting to obtain ferritic stainless steel billet.

[0064] 5. Heat treatment: Heat treatment is performed on ferritic stainless steel billets to change their crystal structure and obtain the desired properties.

[0065] 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.

[0066] 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.

[0067] Example 2

[0068] This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage:

[0069] C: 0.01%, Si: 0.5%, Mn: 0.05%, P: 0.02%, S: 0.02%, Cr: 18%, Mo: 2%, Nb: 0.6%, Ti: 0.005%, balance Fe.

[0070] The preparation method of ferritic stainless steel provided in this embodiment is the same as that in Example 1.

[0071] Example 3

[0072] This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage:

[0073] C: 0.01%, Si: 0.5%, Mn: 0.2%, P: 0.02%, S: 0.02%, Cr: 18%, Mo: 2.5%, Nb: 0.7%, Ti: 0.015%, balance Fe.

[0074] The preparation method of ferritic stainless steel provided in this embodiment is the same as that in Example 1.

[0075] Example 4

[0076] This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage:

[0077] C: 0.01%, Si: 0.1%, Mn: 0.1%, P: 0.01%, S: 0.01%, Cr: 17%, Mo: 2.2%, Nb: 0.6%, Ti: 0.01%, balance Fe.

[0078] The preparation method of ferritic stainless steel provided in this embodiment is the same as that in Example 1.

[0079] Comparative Example 1

[0080] This comparative example provides a 316L stainless steel comprising, by weight percentage: C: 0.03%, Si: 1.0%, Mn: 2.0%, P: 0.04%, S: 0.03%, Cr: 18%, Mo: 2.5%, Ni: 12.0%, balance Fe.

[0081] The preparation method of the 316L stainless steel provided in this comparative example is the same as that in Example 1.

[0082] Comparative Example 2

[0083] This comparative example provides a ferritic stainless steel that comprises, by weight percentage, the following components:

[0084] C: 0.01%, Si: 0.5%, Mn: 0.1%, P: 0.02%, S: 0.02%, Cr: 15%, Mo: 1%, Nb: 0.3%, balance Fe.

[0085] The preparation method of the ferritic stainless steel provided in this comparative example is the same as that in Example 1.

[0086] Comparative Example 3

[0087] This comparative example provides a ferritic stainless steel that comprises, by weight percentage, the following components:

[0088] C: 0.01%, Si: 0.5%, Mn: 0.1%, P: 0.02%, S: 0.02%, Cr: 22%, Mo: 3%, Nb: 1%, Ti: 0.03%, balance Fe.

[0089] The preparation method of the ferritic stainless steel provided in this comparative example is the same as that in Example 1.

[0090] Test case

[0091] To verify the performance of the ferritic stainless steel provided in this application, further tests were conducted on the performance of the ferritic stainless steel prepared in each embodiment and comparative example.

[0092] (1) The corrosion resistance of the ferritic 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 kinetics of pitting corrosion potential of stainless steel in 3.5% sodium chloride solution was measured according to GB / T 17899-2023. The experimental temperature was 65℃.

[0093] The corrosion resistance test results are shown in Figure 2. As can be seen from Figure 2, the new stainless steel material in Example 1 has better pitting corrosion resistance than that in Comparative Example 1.

[0094] (2) The X-ray diffraction curves of the ferritic stainless steel of Example 1 and Comparative Example 1 are shown in Figure 3. As can be seen from Figure 3, compared with Comparative Example 1, the stainless steel material of Example 1 exhibits a completely ferritic structure.

[0095] (3) The changes in high-temperature mechanical properties and mechanical properties after aging of the stainless steel in Example 1 are as follows:

[0096] Figure 4 shows the tensile curves of stainless steel in Example 1 at different temperatures. As can be seen from Figure 4, the tensile properties of Example 1 decrease uniformly with increasing temperature, and the strength and plasticity still remain at a high level.

[0097] Figure 5 shows the evolution of room temperature tensile properties of stainless steel after aging at 475℃ in Example 1. As can be seen from Figure 5, the tensile strength of Example 1 increased significantly after aging at 475℃ for different times, while the plasticity level did not change significantly.

[0098] Figure 6 shows the microstructure of Example 1 after aging, revealing a large number of dispersed micron-sized precipitates that significantly strengthen the material.

[0099] (4) The welding sensitization test of stainless steel in Example 1 is performed 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 scan rate 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 scan rate to the corrosion potential. The maximum current of the two rings is measured. ia represents the maximum anodic polarization direction scan 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.

[0100] Figure 7 shows the EPR curves of the stainless steel straight seam welded pipe samples from the weld zone and non-weld zone in 0.5MH2SO4 + 0.01M KSCN solution at 30℃. As can be seen from Figure 7, the sensitization degree of the stainless steel straight seam welded pipe samples from both the weld zone and non-weld zone in Example 1 is extremely low.

[0101] The results of the reflow welding of stainless steel in Example 1 are shown in Figure 8. As can be seen from Figure 8, 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.

[0102] (5) Thermal conductivity test

[0103] 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 ferritic stainless steel materials of the examples and comparative examples is shown in Table 1.

[0104] Table 1

[0105] Referring to Figure 9 and Table 9, it can be seen that the thermal conductivity of the ferritic stainless steel in Example 1 is 50% higher than that of the 316L stainless steel in Comparative Example 1. The ferritic stainless steels in Examples 1-4 all have high thermal conductivity, indicating that the ferritic stainless steel of this application has excellent thermal conductivity.

[0106] (6) Fatigue resistance test

[0107] The coefficients of thermal expansion of the stainless steel materials of the examples and comparative examples were determined in the range of 25℃-1000℃. The coefficients of thermal expansion of the ferritic stainless steel materials of the examples and comparative examples are shown in Table 2.

[0108] Table 2

[0109] Referring to Figure 10 and Table 10, it can be seen that the coefficient of thermal expansion of the ferritic stainless steel in Example 1 is reduced by 35% compared with the 316L stainless steel in Comparative Example 1. The ferritic stainless steels in Examples 1-4 all have low coefficients of thermal expansion, indicating that the ferritic stainless steel of this application has excellent fatigue resistance.

[0110] In summary, the ferritic stainless steel of this application not only has superior corrosion resistance, but also excellent thermal conductivity and fatigue resistance.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A ferritic stainless steel, comprising the following components by mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 0.8%, 0 < Mn ≤ 1.0%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 17% ≤ Cr ≤ 20%, 1.5% ≤ Mo ≤ 2.5%, 0.5% ≤ Nb ≤ 0.8%, 0 < Ti ≤ 0.02%, the balance being Fe and inevitable impurities.

2. The ferritic stainless steel according to claim 1, wherein, 0.05% ≤ Mn ≤ 0.2%.

3. The ferritic stainless steel according to claim 1 or 2, wherein, 2% ≤ Mo ≤ 2.5%.

4. The ferritic stainless steel according to any one of claims 1-3, wherein, 0.6% ≤ Nb ≤ 0.7%.

5. The ferritic stainless steel according to any one of claims 1-4, wherein, 0.005% ≤ Ti ≤ 0.015%.

6. The ferritic stainless steel according to any one of claims 1-5, wherein, Comprising the following components by mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 0.8%, 0.05 ≤ Mn ≤ 0.2%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 17% ≤ Cr ≤ 20%, 2% ≤ Mo ≤ 2.5%, 0.6% ≤ Nb ≤ 0.7%, 0.005% ≤ Ti ≤ 0.015%, the balance being Fe and inevitable impurities.

7. The ferritic stainless steel according to any one of claims 1-6, wherein, In the range of 200°C - 1000°C, the thermal conductivity of the ferritic stainless steel is 23.0 W / (m·K) - 30.5 W / (m·K); and / or, in the range of 200°C - 1000°C, the thermal expansion coefficient of the ferritic stainless steel is 11.5×(10^-6 / °C) - 14.5×(10^-6 / °C).

8. 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 prepared from the ferritic stainless steel according to any one of claims 1 - 7.

10. A heat exchanger comprising the heat exchanger component according to claim 9.

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