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; cr is greater than or equal to 16% and less than or equal to 20%, 0 lt; n is smaller than or equal to 0.025%, and Cu is larger than or equal to 0.3% and smaller than or equal to 0.8%. The ferritic stainless steel provided by the invention has high heat conductivity coefficient, low expansion coefficient and good 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 long 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 and its applications, heat exchanger components, and heat exchangers. Background Art

[0002] The 304 material is a general-purpose stainless steel material, which is widely used in the manufacture of equipment and components that require good comprehensive properties (corrosion resistance and formability). In the selection of heat exchanger materials, not only certain corrosion resistance but also certain requirements for thermal conductivity and fatigue resistance need to be met. When the 304 stainless steel material is used as a heat exchanger material, although its corrosion resistance meets the requirements, its thermal conductivity and fatigue resistance are not good and cannot meet the requirements of heat exchanger materials. Currently, the commonly used heat exchanger materials also have the problem of relatively high processing costs. Therefore, how to improve its thermal conductivity and fatigue resistance on the basis of the 304 stainless steel material while reducing production costs to obtain a material that meets the requirements of heat exchangers has important research value. Summary of the Invention

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

[0004] In the first aspect of the present invention, a ferritic stainless steel is provided. 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%, 16% ≤ Cr ≤ 20%, 0 < N ≤ 0.025%, 0.3% ≤ Cu ≤ 0.8%, the balance being Fe and inevitable impurities.

[0005] According to the above ferritic stainless steel of the present invention, on the basis of the 304 material, nickel element is removed to obtain a ferritic stainless steel with a higher thermal conductivity coefficient and a lower thermal expansion coefficient, copper element is added, and at the same time, the contents of other elements are changed, especially the contents of manganese element and nitrogen element are changed, and the content of copper element is controlled, which also ensures the corrosion resistance of the ferritic stainless steel of the present application. Thus, the ferritic stainless steel not only has good corrosion resistance but also has excellent thermal conductivity and fatigue resistance.

[0006] According to the above ferritic stainless steel of the present invention, preferably 0.3% ≤ Mn ≤ 0.7%.

[0007] According to the above ferritic stainless steel of the present invention, preferably 0.01 ≤ N ≤ 0.02%.

[0008] For the ferritic stainless steel according to the present invention, preferably 0.5% ≤ Cu ≤ 0.7%.

[0009] 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%, 0.3% ≤ Mn ≤ 0.7%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 16% ≤ Cr ≤ 20%, 0.01 ≤ N ≤ 0.02%, 0.5% ≤ Cu ≤ 0.7%, the balance being Fe and inevitable impurities.

[0010] 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 17.5 W / (m·K) - 33.5 W / (m·K).

[0011] 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 11.8×(10^ -6 / °C) - 15.5×(10^ -6 / °C).

[0012] In the second aspect of the present invention, the present invention provides an 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 provides a heat exchanger component. The heat exchanger component is prepared from the above ferritic stainless steel. Thus, the heat exchanger component has good 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 provides a heat exchanger. The heat exchanger comprises the above heat exchanger component. Thus, the heat exchanger has good heat conduction performance, fatigue resistance 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 stainless steels in Example 1 and Comparative Example 1 of the present invention; Figure 3It is the thermal conductivity curve graph of the ferritic stainless steels obtained in Example 1 and Comparative Example 1 of the present invention; Figure 4 It is the thermal expansion coefficient curve graph 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 in conjunction with the accompanying drawings in the present invention. Apparently, 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 shall fall within the protection scope of the present invention.

[0018] In the first aspect of the present invention, the present invention provides a ferritic stainless steel. The ferritic stainless steel includes 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%, 16% ≤ Cr ≤ 20%, 0 < N ≤ 0.025%, 0.3% ≤ Cu ≤ 0.8%, with the balance being Fe and unavoidable impurities.

[0019] 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%, 0.9%, 1.0%, 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 16%, 17%, 18%, 19%, 20%, etc., or the range between any two of the above values; the N content is 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, etc., or the range between any two of the above values; the Cu content is 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, etc., or the range between any two of the above values.

[0020] According to the present invention, the ferritic stainless steel, based on 304 stainless steel, removes nickel, increases copper, and modifies the content of other elements, particularly manganese and nitrogen, while controlling the copper content. This not only ensures the corrosion resistance of the ferritic stainless steel but also, compared to 304 stainless steel, exhibits a higher thermal conductivity and a lower coefficient of thermal expansion. Therefore, this ferritic stainless steel not only possesses good corrosion resistance but also excellent thermal conductivity and fatigue 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 is known that the alloy maintains a complete ferrite structure below 800℃, which ensures its thermal conductivity and fatigue resistance.

[0021] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.3% ≤ Mn ≤ 0.7%. 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 has a nitrogen content of 0.01 ≤ N ≤ 0.02%. By controlling the nitrogen content within the above range, nitrogen can form nitrides with chromium, which can improve its corrosion resistance and strength, as well as its processing performance and plasticity.

[0023] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.5% ≤ Cu ≤ 0.7%. By controlling the copper content within the above range, the copper element can form a solid solution with elements such as iron and chromium in the ferritic stainless steel, thereby increasing the strength and hardness of the stainless steel and improving its corrosion resistance. Furthermore, the copper element can also promote grain boundary strengthening in ferritic stainless steel, refining its grains and improving its plasticity and toughness.

[0024] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.3% ≤ Mn ≤ 0.7% and 0.01 ≤ N ≤ 0.02%.

[0025] According to embodiments of the present invention, the ferritic stainless steel preferably contains 0.3% ≤ Mn ≤ 0.7% and 0.5% ≤ Cu ≤ 0.7%.

[0026] According to embodiments of the present invention, the ferritic stainless steel preferably has 0.01 ≤ N ≤ 0.02% and 0.5% ≤ Cu ≤ 0.7%.

[0027] 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%, 0.3% ≤ Mn ≤ 0.7%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 16% ≤ Cr ≤ 20%, 0.01 ≤ N ≤ 0.02%, 0.5% ≤ Cu ≤ 0.7%, the balance being Fe and unavoidable impurities. By controlling the content of each component within the above range, the present invention can significantly improve the thermal conductivity and fatigue resistance of the stainless steel material.

[0028] 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 17.5 W / (m·K) - 33.5 W / (m·K).

[0029] According to an embodiment of the present invention, within the range of 200°C - 1000°C, the coefficient of thermal expansion of the above ferritic stainless steel is 11.8×(10^ -6 / °C) - 15.5×(10^ -6 / °C).

[0030] In a 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.

[0031] In a 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 coefficient of thermal expansion. 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.

[0032] 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.

[0033] In a 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.

[0034] For those not specifying specific techniques or conditions 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 not indicating the manufacturer, they are all conventional products that can be obtained through regular channels.

[0035] Example 1 This example provides a ferritic stainless steel which, in mass percentage, comprises the following components: C: 0.01%, Si: 0.5%, Mn: 0.5%, P: 0.02%, S: 0.02%, Cr: 18%, N: 0.01%, Cu: 0.6%, balance Fe.

[0036] 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.

[0037] 2. Mix evenly: Mix the raw materials, which can be done by mechanical mixing or dissolution mixing, to make them evenly mixed.

[0038] 3. Melting: The mixed raw materials are placed in a high-temperature furnace for melting and mixing.

[0039] 4. Casting: Pour the molten ferritic stainless steel liquid into a mold for casting to obtain ferritic stainless steel billet.

[0040] 5. Heat treatment: Heat treatment is performed on ferritic stainless steel billets to change their crystal structure and obtain the desired properties.

[0041] 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.

[0042] 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.

[0043] Example 2 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.5%, Mn: 0.3%, P: 0.02%, S: 0.02%, Cr: 18%, N: 0.01%, Cu: 0.5%, balance Fe.

[0044] The preparation method of ferritic stainless steel in this embodiment is the same as that in Example 1.

[0045] Example 3 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.01%, Si: 0.5%, Mn: 0.7%, P: 0.02%, S: 0.02%, Cr: 18%, N: 0.02%, Cu: 0.7%, balance Fe.

[0046] The preparation method of ferritic stainless steel in this embodiment is the same as that in Example 1.

[0047] Example 4 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: 0.01%, S: 0.01%, Cr: 16%, N: 0.01%, Cu: 0.3%, balance Fe.

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

[0049] Example 5 This embodiment provides a ferritic stainless steel, which comprises the following components by mass percentage: C: 0.025%, Si: 1.0%, Mn: 1.0%, P: 0.04%, S: 0.03%, Cr: 20%, N: 0.025%, Cu: 0.8%, balance Fe.

[0050] The method for preparing stainless steel in this embodiment is the same as that in Example 1.

[0051] Comparative Example 1 This comparative example provides a 304 stainless steel, which comprises the following components by weight percentage: C: 0.08%, Si: 1.0%, Mn: 2.0%, P: 0.045%, S: 0.03%, Cr: 20%, Ni: 8.0%, balance Fe.

[0052] The preparation method of the 304 stainless steel in this comparative example is the same as that in Example 1.

[0053] 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: 18%, N: 0.01%, Cu: 0.2%, balance Fe.

[0054] The preparation method of the ferritic stainless steel in this comparative example is the same as that in Example 1.

[0055] 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: 0.5%, P: 0.02%, S: 0.02%, Cr: 18%, N: 0.01%, Cu: 1.0%, balance Fe.

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

[0057] Comparative Example 4 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: 18%, N: 0.05%, Cu: 1.0%, balance Fe.

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

[0059] 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.

[0060] (1) The corrosion resistance of the stainless steel materials in Example 1 and Comparative Example 1 was tested. The specific method is as follows: according to GB / T 17899-2023, the method for measuring the pitting potential of stainless steel in 3.5% sodium chloride solution, the experimental temperature is 65℃.

[0061] 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.

[0062] (2) 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.

[0063] Table 1

[0064] Combination Figure 3 As shown in Table 3, the thermal conductivity of the ferritic stainless steels in Examples 1-5 is significantly improved compared to the 304 stainless steel material in Comparative Example 1, indicating that the ferritic stainless steel of this application has excellent thermal conductivity. Meanwhile, when the copper content is low (Comparative Example 2), the thermal conductivity decreases significantly, but when the copper content exceeds 0.8% (Comparative Examples 3 and 4), the thermal conductivity does not increase significantly. Therefore, changing the copper content in the material has a significant impact on the thermal conductivity of ferritic stainless steel.

[0065] (3) 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.

[0066] Table 2

[0067] Combination Figure 4 As shown in Table 4, the coefficient of thermal expansion of the ferritic stainless steel in Example 1 is significantly lower than that of the 304 stainless steel in Comparative Example 1, indicating that the ferritic stainless steel of this application has excellent fatigue resistance. Referring to Table 3, although the thermal conductivity did not significantly increase after increasing the copper content, the coefficients of thermal expansion of Comparative Examples 3 and 4 showed significant changes, indicating that increasing the copper content reduces the fatigue resistance of the material.

[0068] In summary, the ferritic stainless steel of this application has corrosion resistance comparable to 304 stainless steel, as well as excellent thermal conductivity and fatigue resistance.

[0069] 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%, 16% ≤ Cr ≤ 20%, 0 < N ≤ 0.025%, 0.3% ≤ Cu ≤ 0.8%, the balance being Fe and unavoidable impurities.

2. The ferritic stainless steel according to claim 1, characterized in that, 0.3% ≤ Mn ≤ 0.7%.

3. The ferritic stainless steel according to claim 1, characterized in that, 0.01≤N≤0.02%。 4. The ferritic stainless steel according to claim 1, characterized in that, 0.5% ≤ Cu ≤ 0.7%.

5. The ferritic stainless steel according to any one of claims 1-4, characterized in that, Comprising the following components by mass percentage: 0 < C ≤ 0.025%, 0 < Si ≤ 1.0%, 0.3% ≤ Mn ≤ 0.7%, 0 < P ≤ 0.04%, 0 < S ≤ 0.03%, 16% ≤ Cr ≤ 20%, 0.01 ≤ N ≤ 0.02%, 0.5% ≤ Cu ≤ 0.7%, the balance being Fe and unavoidable impurities.

6. The ferritic stainless steel according to any one of claims 1-4, characterized in that, In the range of 200 °C - 1000 °C, the thermal conductivity of the ferritic stainless steel is 17.5 W / (m·K) - 33.5 W / (m·K).

7. The ferritic stainless steel according to any one of claims 1-4, characterized in that, Within the temperature range of 200℃ to 1000℃, the coefficient of thermal expansion of the ferritic stainless steel is 11.8 × (10^ -6 / ℃)-15.5×(10^ -6 / ℃).

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, Including the heat exchanger component according to claim 9.

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