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 < = 0.8%, 0lt; mn < = 1.0%, 0lt; p is less than or equal to 0.04%, 0lt; s < = 0.03%, 17% < = Cr < = 20%, 1.5% < = Mo < = 2.5%, 0.5% < = Nb < = 0.8%, 0 lt; less than or equal to 0.02% of Ti, and the balance Fe and inevitable The ferritic stainless steel provided by the invention has a high heat conductivity coefficient, a low expansion coefficient and excellent sensitization intergranular corrosion resistance and chloride ion corrosion resistance, so that the ferritic stainless steel has excellent heat conductivity and fatigue resistance, and the ferritic stainless steel is low in production cost and suitable for industrial production. Particularly, when the ferritic stainless steel is applied to a heat exchanger, the heat exchanger has excellent heat conduction performance and long service life, and the ferritic stainless steel has excellent market application prospects and particularly has great potential advantages in the application aspect of the heat exchanger.

Description

Technical Field

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

[0002] Heat exchangers and the like are usually prepared from 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 the main problem in heat exchangers using chloride-containing liquids as coolants. Therefore, higher requirements are imposed on the corrosion resistance of the stainless steel materials used in heat exchangers.

[0003] 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 glossiness 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 preparation industry. Although 316L has a 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, its thermal conductivity and fatigue resistance are insufficient, and the cost is high.

[0004] Therefore, in order to meet the material properties in the heat exchanger field, it is of great significance to develop materials with good corrosion resistance, thermal conductivity, and fatigue resistance. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the prior art to some extent. For this reason, an object of the present invention is to provide a ferritic stainless steel and its applications, heat exchanger components, and heat exchangers.

[0006] In the first aspect of the present invention, a ferritic stainless steel is provided. The ferritic stainless steel includes 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%, and the balance is Fe and unavoidable impurities.

[0007] According to the above ferritic stainless steel of the present invention, 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 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 synergistically with the Cr element to significantly improve the pitting corrosion resistance, chloride ion corrosion resistance and sensitization 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 enhancing the thermal conductivity and fatigue resistance of the material. Thus, this ferritic stainless steel has excellent thermal conductivity, corrosion resistance and fatigue resistance, and the cost of this ferritic stainless steel is low.

[0008] According to the above ferritic stainless steel of the present invention, it is preferred that 0.05% ≤ Mn ≤ 0.2%.

[0009] According to the above ferritic stainless steel of the present invention, it is preferred that 2% ≤ Mo ≤ 2.5%.

[0010] According to the above ferritic stainless steel of the present invention, it is preferred that 0.6% ≤ Nb ≤ 0.7%.

[0011] According to the above ferritic stainless steel of the present invention, it is preferred that 0.005% ≤ Ti ≤ 0.015%.

[0012] According to the above ferritic stainless steel of the present invention, preferably, it comprises 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 unavoidable impurities.

[0013] According to the above ferritic stainless steel of the present invention, 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).

[0014] According to the above ferritic stainless steel of the present invention, within 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).

[0015] In a second aspect, the present invention proposes the application of the above-mentioned ferritic stainless steel in heat exchangers and electric heating tubes.

[0016] In a third aspect, the present invention provides a heat exchanger component. This heat exchanger component is manufactured using the aforementioned ferritic stainless steel. Consequently, this heat exchanger component exhibits excellent corrosion resistance, high thermal conductivity, and a low coefficient of thermal expansion.

[0017] In a fourth aspect, the present invention provides a heat exchanger. This heat exchanger includes the aforementioned heat exchanger components. Consequently, the heat exchanger exhibits good thermal conductivity and a long service life. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention 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 invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is the equilibrium phase diagram of ferritic stainless steel provided by the present invention; Figure 2 The graph shows the corrosion resistance test results of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of this invention. Figure 3 These are X-ray diffraction curves of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of this invention. Figure 4 This is a tensile curve of the ferritic stainless steel obtained in Example 1 of the present invention at different temperatures; Figure 5 This is a graph showing the evolution of room temperature tensile properties of the ferritic stainless steel obtained in Example 1 of the present invention after aging at 475°C. Figure 6 This is the microstructure of the ferritic stainless steel obtained in Example 1 of the present invention after aging at 475°C for 40 hours; Figure 7 This is an EPR curve of the straight seam welded pipe of ferritic stainless steel obtained in Example 1 of the present invention; Figure 8 This is the brazing microstructure of ferritic stainless steel obtained in Example 1 of the present invention. Figure 9 These are thermal conductivity curves of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of the present invention. Figure 10 This is a graph showing the coefficient of thermal expansion of the ferritic stainless steel obtained in Example 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0020] 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 in conjunction with 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 any creative efforts fall within the protection scope of the present invention.

[0021] In the first aspect of the present invention, a ferritic stainless steel is proposed. The ferritic stainless steel includes 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%, with the balance being Fe and inevitable impurities.

[0022] For example, the C content is 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, etc., or the 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 the 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 the range between any two of the above values; the P content is 0.01%, 0.02%, 0.03%, 0.04%, etc., or the range between any two of the above values; the S content is 0.01%, 0.02%, 0.03%, etc., or the range between any two of the above values; the Cr content is between 17%, 18%, 19%, 20%, etc., or the range between any two of the above values; the 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 values; the Nb content is 0.5%, 0.6%, 0.7%, 0.8%, etc., or the range between any two of the above values; the Ti content is 0.005%, 0.01%, 0.015%, 0.02%, etc., or the range between any two of the above values.

[0023] According to the ferritic stainless steel of the present invention, Nb forms a stable carbide NbC with C, which can refine the grains, improve the material strength and resistance to intergranular corrosion, and Nb and Cr synergistically improve the material's pitting corrosion resistance. Specifically, by controlling the Cr content within the above-mentioned range, the precipitation of Cr-rich second phase can be effectively reduced, thereby improving the material's corrosion resistance, strength, and toughness. Furthermore, controlling the Nb content within the above-mentioned 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 above-mentioned 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 improving 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.

[0024] 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.

[0025] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.05% ≤ Mn ≤ 0.2%. 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.

[0026] According to embodiments of the present invention, the ferritic stainless steel preferably contains 2% ≤ Mo ≤ 2.5%. 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.

[0027] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.6% ≤ Nb ≤ 0.7%. By controlling the niobium content within this range, the present invention allows Nb to form stable NbC carbides with C, refining the grain size and improving the material's strength and resistance to intergranular corrosion. Adding more Nb can also increase the Cr content in the passivation film, thereby improving pitting corrosion resistance.

[0028] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.005% ≤ Ti ≤ 0.015%. By controlling the titanium content within the above range, the Ti element forms Ti(C,N), improving material strength and resistance to intergranular corrosion, while simultaneously preventing excessive Ti element from forming TiN, which could cause surface defects.

[0029] According to an embodiment of the present invention, for the above ferritic stainless steel, preferably 0.05% ≤ Mn ≤ 0.2% and 2% ≤ Mo ≤ 2.5%.

[0030] According to an embodiment of the present invention, for the above ferritic stainless steel, preferably 0.05% ≤ Mn ≤ 0.2%, 2% ≤ Mo ≤ 2.5%, and 0.6% ≤ Nb ≤ 0.7%.

[0031] According to an embodiment of the present invention, for the above ferritic stainless steel, preferably 0.05% ≤ Mn ≤ 0.2%, 2% ≤ Mo ≤ 2.5%, and 0.005% ≤ Ti ≤ 0.015%.

[0032] According to an embodiment of the present invention, for the above ferritic stainless steel, preferably 0.6% ≤ Nb ≤ 0.7% and 0.005% ≤ Ti ≤ 0.015%.

[0033] According to an embodiment of the present invention, for the above ferritic stainless steel, preferably 2% ≤ Mo ≤ 2.5%, 0.6% ≤ Nb ≤ 0.7%, and 0.005% ≤ Ti ≤ 0.015%.

[0034] According to an embodiment of the present invention, the above ferritic stainless steel preferably comprises 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%, with the balance being 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.

[0035] 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 23.0 W / (m·K) - 30.5 W / (m·K).

[0036] 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 11.5×(10^-6 / °C) - 14.5×(10^-6 / °C).

[0037] 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.

[0038] In a third aspect, the present invention provides a heat exchanger component. This heat exchanger component is manufactured using the aforementioned ferritic stainless steel. Therefore, the heat exchanger component exhibits excellent corrosion resistance, high thermal conductivity, and a low coefficient of thermal expansion. It should be noted that the features and advantages described above for ferritic stainless steel also apply to this heat exchanger component, and will not be repeated here.

[0039] According to embodiments of the present invention, heat exchanger components include, but are not limited to, at least one of heat exchange tubes and heat exchange fins.

[0040] In a fourth aspect, the present invention provides a heat exchanger. This heat exchanger includes the aforementioned heat exchanger components. Therefore, the heat exchanger exhibits good thermal conductivity and a long service life. It should be noted that the features and advantages described for the aforementioned heat exchanger components also apply to this heat exchanger, and will not be repeated here.

[0041] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0042] Example 1 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.5%, Mn: 0.1%, P: 0.02%, S: 0.02%, Cr: 18%, Mo: 2.2%, Nb: 0.6%, Ti: 0.01%, balance Fe.

[0043] 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.

[0044] 2. Mix evenly: Mix the raw materials, which can be done by mechanical mixing or dissolution mixing, to make them evenly mixed.

[0045] 3. Melting: The mixed raw materials are placed in a high-temperature furnace for melting and mixing.

[0046] 4. Casting: Pour the molten ferritic stainless steel liquid into a mold for casting to obtain ferritic stainless steel billet.

[0047] 5. Heat treatment: Heat treatment is performed on ferritic stainless steel billets to change their crystal structure and obtain the desired properties.

[0048] 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.

[0049] 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.

[0050] Example 2 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.5%, Mn: 0.05%, P: 0.02%, S: 0.02%, Cr: 18%, Mo: 2%, Nb: 0.6%, Ti: 0.005%, balance Fe.

[0051] The preparation method of ferritic stainless steel provided in this embodiment is the same as that in Example 1.

[0052] Example 3 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.5%, Mn: 0.2%, P: 0.02%, S: 0.02%, Cr: 18%, Mo: 2.5%, Nb: 0.7%, Ti: 0.015%, balance Fe.

[0053] The preparation method of ferritic stainless steel provided in this embodiment is the same as that in Example 1.

[0054] Example 4 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.1%, Mn: 0.1%, P: 0.01%, S: 0.01%, Cr: 17%, Mo: 2.2%, Nb: 0.6%, Ti: 0.01%, balance Fe.

[0055] The preparation method of ferritic stainless steel provided in this embodiment is the same as that in Example 1.

[0056] Comparative Example 1 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.

[0057] The preparation method of the 316L stainless steel provided in this comparative example is the same as that in Example 1.

[0058] 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: 0.1%, P: 0.02%, S: 0.02%, Cr: 15%, Mo: 1%, Nb: 0.3%, balance Fe.

[0059] The preparation method of the ferritic stainless steel provided in this comparative example is the same as that in Example 1.

[0060] 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: 0.1%, P: 0.02%, S: 0.02%, Cr: 22%, Mo: 3%, Nb: 1%, Ti: 0.03%, balance Fe.

[0061] The preparation method of the ferritic stainless steel provided in this comparative example is the same as that in Example 1.

[0062] 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.

[0063] (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 dynamics of the pitting potential of stainless steel in 3.5% sodium chloride solution was measured according to GB / T17899-2023. The experimental temperature was 65℃.

[0064] 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 better pitting corrosion resistance than Comparative Example 1.

[0065] (2) The X-ray diffraction curves of the ferritic stainless steel of Example 1 and Comparative Example 1 of the present invention are shown in the figure. 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.

[0066] (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 4It 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.

[0067] 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℃ for different times, the tensile strength of Example 1 increased significantly, while the plasticity level did not change significantly.

[0068] Figure 6 This is a microstructure diagram of Example 1 after aging. Numerous dispersed micron-sized precipitates can be observed, which significantly strengthen the material.

[0069] (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.

[0070] 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.

[0071] 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.

[0072] (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 ferritic stainless steel materials of the examples and comparative examples is shown in Table 1.

[0073] Table 1

[0074] Combination Figure 9As shown in Table 9, 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.

[0075] (6) Fatigue resistance test 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.

[0076] Table 2

[0077] Combination Figure 10 As shown in Table 10, the coefficient of thermal expansion of the ferritic stainless steel in Example 1 was reduced by 35% compared with the 316L stainless steel in Comparative Example 1. The ferritic stainless steels in Examples 1-4 all had low coefficients of thermal expansion, indicating that the ferritic stainless steel of this application has excellent fatigue resistance.

[0078] In summary, the ferritic stainless steel of this application not only has superior corrosion resistance, but also excellent thermal conductivity and fatigue resistance.

[0079] 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 ≤ 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 unavoidable impurities.

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

3. The ferritic stainless steel according to claim 1, characterized in that, 2% ≤ Mo ≤ 2.5%.

4. The ferritic stainless steel according to claim 1, characterized in that, 0.6% ≤ Nb ≤ 0.7%.

5. The ferritic stainless steel according to claim 1, characterized in that, 0.005% ≤ Ti ≤ 0.015%.

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 ≤ 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.

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 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, 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, Comprising the heat exchanger component according to claim 9.

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