Title of the invention: Ferritic stainless steel excellent in high temperature oxidation resistance and its manufacturing method
Technical field
[One]
The present invention relates to an optimal design method of ferritic stainless steel for preventing high-temperature oxidation, and more particularly, to a ferritic stainless steel capable of suppressing high-temperature oxidation through the generation of an effective oxide scale, and a manufacturing method thereof. will be.
Background
[2]
Ferritic stainless steel is a steel material with high cost competitiveness compared to austenitic stainless steel because it has excellent corrosion resistance while adding less expensive alloying elements. Ferritic stainless steel is used for exhaust-manifold, collector cone, etc. with an exhaust gas temperature of 800℃ or higher, but when exposed to a high-temperature environment for a long time, high-temperature oxidation occurs and the durability of the part is deteriorated.
[3]
In the past, products have been developed in terms of alloy components and manufacturing methods simply to increase high-temperature strength, but research on the oxidation scale of the surface layer of stainless steel to suppress high-temperature oxidation when exposed to high-temperature environments for a long time in addition to increasing high-temperature strength is insufficient. .
Detailed description of the invention
Technical challenge
[4]
Embodiments of the present invention are intended to provide a ferritic stainless steel and a method of manufacturing the same, which can increase durability of parts by suppressing high-temperature oxidation when exposed to high-temperature environments as well as increasing high-temperature strength.
Means of solving the task
[5]
Ferritic stainless steel having excellent high temperature oxidation resistance according to an embodiment of the present invention is, by weight, Cr: 10 to 30%, Si: 0.2 to 1.0%, Mn: 0.1 to 2.0%, W: 0.3 to 2.5% , Ti: 0.001 to 0.15%, Al: 0.001 to 0.1%, the remaining Fe and inevitable impurities are included, and the following formula (1) is satisfied.
[6]
(1) W/(Ti+Al) ≥ 10
[7]
Here, W, Ti, and Al mean the content (% by weight) of each element.
[8]
In addition, according to an embodiment of the present invention, when the stainless steel is exposed at 900° C. or higher for 200 hours or more, a W, Si oxide film ([W,Si]-Oxide) may be formed on the surface layer.
[9]
In addition, according to an embodiment of the present invention, the thickness of the W, Si oxide film may be 5 μm or more.
[10]
In addition, according to an embodiment of the present invention, the stainless steel may contain 0.01 to 1.0% by weight of W Laves Phase precipitates.
[11]
In addition, according to an embodiment of the present invention, the stainless steel further comprises C: 0.001 to 0.01%, N: 0.001 to 0.01%, Nb: 0.3 to 0.6%, Mo: 0.3 to 2.5%, and Cu: 0.2% or less. And, C+N: 0.018% or less may be satisfied.
[12]
In addition, according to an embodiment of the present invention, the stainless steel contains 0.01 to 1.0% by weight of at least one of W Laves Phase precipitates, Nb Laves phase precipitates, and Mo Laves phase precipitates, and the It may contain 5% by weight or more of W based on 100% by weight of the Laves-phase precipitate.
[13]
In addition, according to an embodiment of the present invention, the W Laves phase precipitate may include any one or more selected from the group consisting of Fe 2 W, FeCrW, Cr 2 W.
[14]
In addition, according to an embodiment of the present invention, the Nb Laves phase precipitate may include any one or more selected from the group consisting of Fe 2 Nb, FeCrNb, and Cr 2 Nb.
[15]
In addition, according to an embodiment of the present invention, the Mo raves phase precipitate may include any one or more selected from the group consisting of Fe 2 Mo, FeCrMo, Cr 2 Mo.
[16]
Further, according to an embodiment of the present invention, the inevitable impurities may include any one or more of P: 0.05% or less, S: 0.005% or less, Mg: 0.0002 to 0.001%, and Ca: 0.0004 to 0.002%.
[17]
Ferritic stainless steel manufacturing method having excellent high temperature oxidation resistance according to an embodiment of the present invention, in weight %, Cr: 10 to 30%, Si: 0.2 to 1.0%, Mn: 0.1 to 2.0%, W: 0.3 to 2.5%, Ti: 0.001 to 0.15%, Al: 0.001 to 0.1%, including the remaining Fe and inevitable impurities, including the step of aging a cold-rolled annealing material that satisfies the following formula (1).
[18]
(1) W/(Ti+Al) ≥ 10
[19]
Here, W, Ti, and Al mean the content (% by weight) of each element.
[20]
Further, according to an embodiment of the present invention, the aging treatment may be performed at 400 to 600° C. for 30 to 90 minutes.
[21]
In addition, according to an embodiment of the present invention, the cold rolled annealed material is C: 0.001 to 0.01%, N: 0.001 to 0.01%, Nb: 0.3 to 0.6%, Mo: 0.3 to 2.5% and Cu: 0.2% or less more And, C+N: 0.018% or less may be satisfied.
Effects of the Invention
[22]
The ferritic stainless steel according to the embodiment of the present invention has a uniform W and Si oxide film formed after 200 hours or more exposure at 900°C or higher, thereby reducing the amount of high-temperature oxidation by 20% or more compared to the previous one. Durability can be increased.
Brief description of the drawing
[23]
1 is a schematic diagram of a behavior of forming an oxide scale when exposed to high temperatures for a long time when the W/(Ti+Al) value is less than 10.
[24]
FIG. 2 is a schematic diagram of a behavior of forming an oxide scale when exposed to high temperatures for a long time when a W/(Ti+Al) value is 10 or more.
[25]
3 is a graph showing the correlation of [W,Si]-Oxide thickness after exposure at 900° C. for 200 hours according to W/(Ti+Al) values.
[26]
Figure 4 is a Fe-SEM photograph showing the composition of the oxide scale of the cross-section of the invention steel after exposure to 900 ℃ 200 hours.
[27]
5 is a graph showing the correlation between the thickness of [W,Si]-Oxide formed after 200 hours exposure at 900° C. and the weight increase due to oxidation.
Best mode for carrying out the invention
[28]
Ferritic stainless steel having excellent high temperature oxidation resistance according to an embodiment of the present invention is, by weight, Cr: 10 to 30%, Si: 0.2 to 1.0%, Mn: 0.1 to 2.0%, W: 0.3 to 2.5% , Ti: 0.001 to 0.15%, Al: 0.001 to 0.1%, the remaining Fe and inevitable impurities are included, and the following formula (1) is satisfied.
[29]
(1) W/(Ti+Al) ≥ 10
[30]
Here, W, Ti, and Al mean the content (% by weight) of each element.
Mode for carrying out the invention
[31]
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are presented in order to sufficiently convey the spirit of the present invention to those of ordinary skill in the art to which the present invention pertains. The present invention is not limited only to the examples presented herein and may be embodied in other forms. In the drawings, in order to clarify the present invention, portions not related to the description may be omitted, and sizes of components may be somewhat exaggerated to help understanding.
[32]
In addition, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.
[33]
Singular expressions include plural expressions, unless the context clearly has exceptions.
[34]
The present invention defines an effective oxide scale configuration for suppressing high temperature oxidation, with respect to an optimal design method of ferritic stainless steel for preventing high-temperature oxidation of automobile exhaust system parts, and a component system for generating a target oxide scale. And parameters are presented.
[35]
Ferritic stainless steel having excellent high temperature oxidation resistance according to an embodiment of the present invention is, by weight, Cr: 10 to 30%, Si: 0.2 to 1.0%, Mn: 0.1 to 2.0%, W: 0.3 to 2.5% , Ti: 0.001 to 0.15%, Al: 0.001 to 0.1%, the remaining Fe and inevitable impurities are included, and the following formula (1) is satisfied.
[36]
(1) W/(Ti+Al) ≥ 10
[37]
Hereinafter, the reason for the numerical limitation of the content of the alloy component element in the examples of the present invention will be described. Hereinafter, unless otherwise specified, the unit is% by weight.
[38]
The content of Cr is 10 to 30%.
[39]
Cr is an element effective in improving the corrosion resistance of steel, and in the present invention, it is added at least 10%. However, if the content is excessive, not only the manufacturing cost increases, but also there is a problem of intergranular corrosion, so it is limited to 30% or less.
[40]
The content of Si is 0.2 to 1.0%.
[41]
Si is an element added for deoxidation of molten steel and stabilization of ferrite during steel making, and is added at least 0.2% in the present invention. However, if the content is excessive, the ductility of the steel decreases due to hardening of the material, so it is limited to less than 1.0%.
[42]
The content of Mn is 0.1 to 2.0%.
[43]
Mn is an element effective in improving corrosion resistance, and in the present invention, 0.1% or more is added, and more preferably 0.5% or more is added. However, if the content is excessive, the generation of Mn-based fumes rapidly increases during welding, resulting in a decrease in weldability, and the ductility of the steel decreases due to excessive MnS precipitate formation, so it is limited to 2.0% or less, more preferably 1.5% or less. do.
[44]
The content of W is 0.3 to 2.5%.
[45]
W serves to increase the corrosion resistance of ferritic stainless steel and at the same time improve high-temperature strength, and increase high-temperature sound absorption. Therefore, it is preferable to add 0.3% or more. However, if the content is excessive, brittleness occurs due to the formation of intermetallic precipitates. Therefore, it is desirable to limit the content to 2.5% or less.
[46]
The content of Ti is 0.001 to 0.15%.
[47]
Ti is effective in reducing the amount of solid solution C and N in steel by fixing C and N and improving the corrosion resistance of steel, but it has high-temperature sound absorption due to the interference of short range diffusion of solid solution W and Mo at a high temperature of 800℃ or higher. Because it decreases, the amount must be limited. However, in order to reduce the Ti content to an extremely low level, the range is limited to the level of 0.001 to 0.15% because additional steelmaking costs increase.
[48]
The content of Al is 0.001 to 0.1%.
[49]
Al is a strong deoxidizing agent, serves to lower the content of oxygen in molten steel, and is added by 0.001% or more in the present invention. However, if the content is excessive, a sleeve defect of the cold-rolled strip occurs due to an increase in non-metallic inclusions, and at the same time, weldability is deteriorated, and thus it is limited to 0.1% or less.
[50]
When the above equation (1) is satisfied, the diffusion of the surface layer of W and Si is activated, and when exposed for 200 hours or more at 900°C or higher, a W, Si oxide film ([W,Si]-Oxide) may be formed on the surface of the stainless steel. . The W, Si oxide film may be uniformly formed to a thickness of 5 μm or more. [W,Si]-Oxide oxide film acts as a barrier to prevent diffusion of Fe, Cr, and Mn in the base material, thereby suppressing additional high-temperature oxidation.
[51]
1 is a schematic diagram of a behavior of forming an oxide scale when exposed to high temperatures for a long time when the W/(Ti+Al) value is less than 10. FIG. 2 is a schematic diagram of a behavior of forming an oxide scale when exposed to high temperatures for a long time when a W/(Ti+Al) value is 10 or more.
[52]
In general, a Mn oxide film (Mn Oxide) is formed on the outermost layer on the surface layer of ferritic stainless steel, and an Fe, Cr oxide film ([Fe,Cr]-Oxide) is formed between the base material and the Mn oxide film.
[53]
When the W/(Ti+Al) value is less than 10, the TiO 2 , Al 2 O 3 oxide film of non-uniform form is formed as shown in FIG. 1 in the Ti and Al content according to the component system of the present invention , which is Fe, Cr Since the diffusion of Mn and O cannot be suppressed, the amount of oxidation at high temperature increases when exposed to high temperature for a long time. On the other hand, when the W/(Ti+Al) value is 10 or more, as shown in FIG. 2, a uniform W, Si oxide film ([W,Si]-Oxide) of 5 μm or more is formed, and Fe, Cr, Mn, O Further high temperature oxidation can be suppressed by preventing the diffusion of.
[54]
In addition, according to an embodiment of the present invention, the stainless steel is C: 0.001 to 0.01%, N: 0.001 to 0.01%, Nb: 0.3 to 0.6%, Mo: 0.3 to 2.5%, and Cu: more than 0.2% Can include. And, C+N may satisfy 0.018% or less.
[55]
The content of C is 0.001 to 0.01%.
[56]
C is an element that greatly affects the strength of a steel material, and if the content is excessive, the strength is excessively increased and the ductility is lowered, so it is limited to 0.01% or less. However, when the content is low, the strength is excessively decreased, and the lower limit thereof may be limited to 0.001% or more.
[57]
The content of N is 0.001 to 0.01%.
[58]
N is an element that serves to accelerate recrystallization by depositing austenite during hot rolling, and in the present invention, 0.001% or more is added. However, if the content is excessive, the ductility of the steel is deteriorated, and the content is limited to 0.01% or less.
[59]
C+N is 0.018% or less.
[60]
If C+N is too high, intergranular corrosion may occur due to the formation of intergranular carbonitride due to insufficient stabilization ratio. To prevent this, it is desirable to manage C+N to 0.018% or less.
[61]
The content of Nb is 0.3 to 0.6%.
[62]
Nb combines with solid solution C to precipitate NbC, thereby lowering the solid solution C content, thereby increasing corrosion resistance, and increasing high temperature strength. Therefore, it is preferable to add 0.3% or more in the present invention. However, if the content is excessive, it is preferable to limit the content to 0.6% or less because it inhibits recrystallization and impairs moldability.
[63]
The content of Mo is 0.3 to 2.5%.
[64]
Mo increases the corrosion resistance of ferritic stainless steel and at the same time improves high-temperature strength, and increases high-temperature sound absorption. Therefore, it is preferable to add 0.3% or more. However, if the content is excessive, brittleness occurs due to the formation of intermetallic precipitates. Therefore, it is desirable to limit the content to 2.5% or less.
[65]
The content of Cu is 0.2% or less.
[66]
Cu has an effect of increasing corrosion resistance in an exhaust system condensate environment. Therefore, it is preferable to add 0.01% or more when adding. However, if the content is excessive, the ductility is lowered and the molding quality is deteriorated. Therefore, it is preferable to limit it to 0.2% or less.
[67]
According to an embodiment of the present invention, any one or more of P: 0.05% or less, S: 0.005% or less, Mg: 0.0002 to 0.001%, and Ca: 0.0004 to 0.002% may be included as inevitable impurities.
[68]
The content of P is 0.05% or less.
[69]
P is an impurity that is inevitably contained in steel and is an element that causes grain boundary corrosion during pickling or impairs hot workability, so it is desirable to control its content as low as possible. In the present invention, the upper limit of the P content is managed as 0.05%.
[70]
The content of S is 0.005% or less.
[71]
S is an impurity that is unavoidably contained in steel, and is an element that segregates at grain boundaries and is the main cause of impairing hot workability, so it is desirable to control its content as low as possible. In the present invention, the upper limit of the S content is managed as 0.005%.
[72]
The content of Mg is 0.0002 to 0.001%.
[73]
Mg is an element introduced for deoxidation in the steel making process and remains as an impurity after the deoxidation process. However, if the content is excessive, the content is limited to 0.001% or less because it impairs moldability, and since it is impossible to completely remove it, it is preferable to manage it to 0.0002% or more.
[74]
The content of Ca is 0.0004 to 0.002%.
[75]
Ca is an element introduced for deoxidation in the steel making process and remains as an impurity after the deoxidation process. However, if the content is excessive, it is limited to 0.002% or less because it impairs corrosion resistance, and since it is impossible to completely remove it, it is preferable to manage it to 0.0004% or more.
[76]
Next, a method of manufacturing a ferritic stainless steel having excellent high-temperature oxidation resistance according to an embodiment of the present invention will be described.
[77]
The ferritic stainless steel having excellent high-temperature oxidation resistance of the present invention can be manufactured to a cold-rolled annealed material through a conventional manufacturing process, and includes the step of aging the cold-rolled annealed material at 400 to 600°C for 30 to 90 minutes. do.
[78]
For example, Cr: 10 to 30%, Si: 0.2 to 1.0%, Mn: 0.1 to 2.0%, W: 0.3 to 2.5%, Ti: 0.001 to 0.15%, Al: 0.001 to 0.1%, remaining Fe and inevitable A slab containing impurities and satisfying a W/(Ti+Al) value of 10 or more may be hot-rolled, hot-rolled annealing, cold-rolled, and cold-rolled annealed to produce a cold-rolled annealed material.
[79]
In addition, C, N, Nb, Mo, and Cu in the above-described range may be further included, and P, S, Mg, and Ca may be included as impurities.
[80]
By satisfying the above formula (1) and subjecting the cold-rolled annealing material containing Nb and Mo to an aging treatment, a Laves phase precipitate can be deposited in the stainless steel structure. [Fe,Cr] 2 [W, Nb, Mo] Laves-like precipitate can be represented by the aging treatment 0.01 to 1.0% by weight in the stainless steel structure can be precipitated. In order to precipitate the amount of precipitation in the above range, the relationship between the aging treatment temperature and time may be adjusted, preferably at 400 to 600°C for 30 to 90 minutes.
[81]
If the Laves phase precipitate containing W is excessively precipitated by 1.0% by weight or more, the high temperature strength decreases due to the decrease in solid solution W, Nb, and Mo, and the risk of brittle fracture increases. The amount should be limited to 1.0% by weight or less.
[82]
The W raves phase precipitate may include any one or more selected from the group consisting of Fe 2 W, FeCrW, and Cr 2 W, and the Nb raves phase precipitate is selected from the group consisting of Fe 2 Nb, FeCrNb, and Cr 2 Nb. It may include any one or more, and the Mo raves phase precipitate may include any one or more selected from the group consisting of Fe 2 Mo, FeCrMo, Cr 2 Mo.
[83]
Based on 100% by weight of the precipitated Laves-phase precipitate ([Fe,Cr] 2 [W,Nb,Mo]), W should be included in an amount of 5% by weight or more. This is because, when the Laves-like precipitate containing W is present on the surface of the stainless steel, it acts as a seed for the generation of W and Si oxide films ([W,Si]-Oxide) when exposed at 900°C or higher for 200 hours or longer. After 200 hours or more exposure at 900°C or higher, the W and Si oxide films are uniformly formed, so that the amount of high-temperature oxidation can be reduced by 20% or more, compared to the previous one, and the 900°C high-temperature strength (TS) value can be 40 MPa or more.
[84]
[85]
Hereinafter will be described in more detail through a preferred embodiment of the present invention.
[86]
Example
[87]
Using the stainless steel lab scale melting and ingot production equipment, a 20mm bar sample was prepared with the alloy component system shown in Table 1 below. After reheating at 1,200°C and hot rolling to 6mm, hot rolling annealing was performed at 1,100°C, and cold rolling to 2.0mm and annealing at 1,100°C. In addition, the cold-rolled annealed plate was aged at 500°C for 1 hour to produce a final product.
[88]
[Table 1]
division C Si Mn Cr Mo Nb W Ti Al Cu N C+N
Invention Lesson 1 0.007 0.3 0.6 19.3 0.5 0.5 1.1 0.01 0.01 0.1 0.006 0.013
Invention Lesson 2 0.005 0.4 0.6 18.7 0.5 0.5 0.8 0.01 0.01 0.1 0.007 0.012
Invention Lesson 3 0.006 0.3 0.7 19.1 0.6 0.4 1.0 0.04 0.03 0.1 0.006 0.012
Invention Lesson 4 0.006 0.3 0.7 19.5 0.5 0.5 0.6 0.02 0.01 0.1 0.006 0.012
Comparative Steel 1 0.005 0.3 0.6 18.8 0.5 0.5 1.2 0.1 0.06 0.1 0.007 0.012
Comparative lecture 2 0.008 0.4 0.6 19.5 0.6 0.5 1.3 0.2 0.1 0.1 0.006 0.014
Comparative lecture 3 0.006 0.4 0.7 18.9 0.6 0.4 1.4 0.1 0.3 0.1 0.006 0.012
Comparative lecture 4 0.006 0.4 0.9 19.1 0.5 0.5 2.7 0.1 0.07 0.1 0.007 0.013
[89]
The final product was cut into 100mm×100mm size and heat-treated at 900°C for 200 hours in a Box Furnace. The weight before and after the heat treatment was measured to evaluate the weight increase or decrease of the oxide film. After the heat treatment, the short side portion of the specimen was observed with Fe-SEM to evaluate the composition, structure, and thickness of the oxide scale, and are shown in FIG. 4. High-temperature strength was evaluated after processing the JIS-13B tensile sample and heating it to 900°C in a tensile machine.
[90]
[Table 2]
division W/(Ti+Al) Isothermal oxidation at 900℃ for 200 hours 900℃ high temperature strength (MPa)
Uniform [W,Si]-Oxide thickness (㎛) Generation of heterogeneous [Ti,Al]-Oxide Weight gain (mg/cm 2 )
Invention Lesson 1 55.0 15 × 2.9 45
Invention Lesson 2 40.0 12 × 3.0 43
Invention Lesson 3 14.3 6 × 3.2 47
Invention Lesson 4 20.0 7 × 3.1 41
Comparative Steel 1 7.5 0 ○ 4.0 46
Comparative lecture 2 4.3 0 ○ 4.1 47
Comparative lecture 3 3.5 0 ○ 4.3 45
Comparative lecture 4 15.9 - - - -
[91]
3 is a graph showing the correlation of [W,Si]-Oxide thickness after exposure at 900° C. for 200 hours according to W/(Ti+Al) values.
[92]
Referring to FIG. 3 together with Tables 1 and 2, Inventive Steels 1 to 4 satisfy the component system range of the present invention and have a W/(Ti+Al) value of 10 or more, and thus uniform W, Si oxide films ([W,Si ]-Oxide) was found to have a thickness of 6㎛ or more. In addition, non-uniform Ti and Al oxide films (TiO 2 , Al 2 O 3 ) were not formed. On the contrary, in Comparative Examples 1 to 3, even though W was sufficiently added, the content of Ti and/or Al was high, so that the W/(Ti+Al) value was less than 10. As a result, the uniform W, Si oxide film ([W ,Si]-Oxide) was not produced.
[93]
On the other hand, Comparative Steel 4 satisfies Equation (1) according to the present invention with W: 2.7%, Ti: 0.1%, and Al: 0.07%, but the W content exceeded 2.5%, causing plate breakage during manufacture. As described above, this was confirmed as a brittle problem due to the formation of precipitates of intermetallic compounds due to excessive W content. Therefore, it was found that the upper limit of the W content should be limited to 2.5% or less.
[94]
Figure 4 is a Fe-SEM photograph showing the composition of the oxide scale of the cross-section of the invention steel after exposure to 900 ℃ 200 hours. Referring to FIG. 4, it can be seen that an oxide film is formed on a matrix, and a W, Si oxide film ([W,Si]-Oxide) is formed on the matrix through the distribution of O, W, and Si. there was.
[95]
5 is a graph showing the correlation between the thickness of [W,Si]-Oxide formed after 200 hours exposure at 900° C. and the weight increase due to oxidation. Referring to Figure 5 along with Tables 1 and 2, it can be seen that when a uniform W, Si oxide film of 5㎛ or more is formed through weight increase, diffusion of Fe, Cr, Mn, O is prevented, thereby inhibiting additional high-temperature oxidation. there was.
[96]
As described above, although exemplary embodiments of the present invention have been described, the present invention is not limited thereto, and those of ordinary skill in the art are within the scope of not departing from the concept and scope of the following claims. It will be appreciated that various modifications and variations are possible.
Industrial availability
[97]
The ferritic stainless steel according to the present invention can be expected to suppress high temperature oxidation and increase durability at high temperature because a uniform oxide layer is formed in a high-temperature exhaust system actual use environment.
Claims
[Claim 1]
In% by weight, Cr: 10 to 30%, Si: 0.2 to 1.0%, Mn: 0.1 to 2.0%, W: 0.3 to 2.5%, Ti: 0.001 to 0.15%, Al: 0.001 to 0.1%, remaining Fe and unavoidable Ferritic stainless steel containing impurities and having excellent high temperature oxidation resistance satisfying the following formula (1). (1) W/(Ti+Al) ≥ 10 (here, W, Ti, and Al mean the content (% by weight) of each element)
[Claim 2]
The ferritic stainless steel of claim 1, wherein the stainless steel is a ferritic stainless steel having excellent high-temperature oxidation resistance in which a W, Si oxide film ([W,Si]-Oxide) is formed on a surface layer when exposed at 900°C or higher for 200 hours or longer.
[Claim 3]
The ferritic stainless steel according to claim 2, wherein the W, Si oxide film has a thickness of 5 µm or more.
[Claim 4]
The ferritic stainless steel of claim 1, wherein the stainless steel contains 0.01 to 1.0% by weight of W Laves Phase precipitates.
[Claim 5]
The method of claim 1, wherein the stainless steel further comprises C: 0.001 to 0.01%, N: 0.001 to 0.01%, Nb: 0.3 to 0.6%, Mo: 0.3 to 2.5%, and Cu: 0.2% or less, and C +N: Ferritic stainless steel with excellent high temperature oxidation resistance satisfying 0.018% or less.
[Claim 6]
The method of claim 5, wherein the stainless steel contains 0.01 to 1.0% by weight of at least one of W Laves Phase precipitates, Nb Laves phase precipitates, and Mo Laves phase precipitates, and the Laves phase precipitate Ferritic stainless steel with excellent high temperature oxidation resistance containing 5% by weight or more of W based on 100% by weight.
[Claim 7]
The ferritic stainless steel according to claim 4 or 6, wherein the W- laves phase precipitate comprises at least one selected from the group consisting of Fe 2 W, FeCrW, and Cr 2 W.
[Claim 8]
The ferritic stainless steel according to claim 6, wherein the Nb Laves-phase precipitate comprises at least one selected from the group consisting of Fe 2 Nb, FeCrNb, and Cr 2 Nb.
[Claim 9]
[7] The ferritic stainless steel according to claim 6, wherein the Mo laves- phase precipitate comprises at least one selected from the group consisting of Fe 2 Mo, FeCrMo, and Cr 2 Mo.
[Claim 10]
According to claim 1, wherein the inevitable impurities, P: 0.05% or less, S: 0.005% or less, Mg: 0.0002 to 0.001%, and Ca: ferritic excellent high temperature oxidation resistance including any one or more of 0.0004 to 0.002% Stainless steel.
[Claim 11]
In% by weight, Cr: 10 to 30%, Si: 0.2 to 1.0%, Mn: 0.1 to 2.0%, W: 0.3 to 2.5%, Ti: 0.001 to 0.15%, Al: 0.001 to 0.1%, remaining Fe and unavoidable A method for manufacturing ferritic stainless steel having excellent high-temperature oxidation resistance, comprising the step of aging a cold-rolled annealing material containing impurities and satisfying the following formula (1). (1) W/(Ti+Al) ≥ 10 (here, W, Ti, and Al mean the content (% by weight) of each element)
[Claim 12]
The method of claim 11, wherein the aging treatment is performed at 400 to 600°C for 30 to 90 minutes.
[Claim 13]
The method of claim 11, wherein the cold rolled annealed material further comprises C: 0.001 to 0.01%, N: 0.001 to 0.01%, Nb: 0.3 to 0.6%, Mo: 0.3 to 2.5%, and Cu: 0.2% or less, and C+ A method for producing ferritic stainless steel having excellent high-temperature oxidation resistance satisfying N: 0.018% or less.