TW200946694A - Ferritic stainless steel with excellent heat resistance and toughness - Google Patents

Abstract

Provided is a ferritic stainless steel having excellent thermal fatigue characteristics and oxidation resistance, without the addition of expensive elements such as molybdenum and tungsten, and having toughness equivalent to or greater than that of Type 429. Specifically, the ferritic stainless steel has, by mass: no more than 0.015% carbon, no more than 0.5% silicon, no more than 0.5% manganese, no more than 0.04% phosphorus, no more than 0.006% sulfur, no more than 16% to 20% chromium, no more than 0.015% nitrogen, between 0.3% and 0.55% niobium, no more than 0.1% titanium, no more than 0.1% molybdenum, no more than 0.1% tungsten, between 1.0% and 2.5% copper, and between 0.2% to 1.2% aluminum, with the remainder comprising iron and unavoidable impurities.

Description

200946694 VI. Description of the Invention: [Technical Field] The present invention relates to a steel containing Cr, in particular to an exhaust pipe suitable for use in an automobile or a motorcycle. The converter case or the exhaust electric duct of the thermal electric power plant is equal to the exhaust system component used in the high temperature environment, and has high heat resistance (thermal fatigue). Resistance), oxidative resistance, and ferrite stainless steel excellent in the toughness of the base material. [Prior Art] Thermal exhaust characteristics and resistance are required for exhaust system components such as an exhaust manifold, an exhaust pipe, a converter casing, and a muffer used in an exhaust system environment of a vehicle. Oxidation properties (hereinafter, both properties are referred to as "heat resistance") are excellent. For applications requiring such heat resistance, steels containing Cr such as Type 429 (14Cr-0· 9Si-0. 4Nb) which are added with Nb and Si are used in many cases. However, with the improvement of engine performance, the "exhaust gas temperature" rises to a temperature as high as 900 °C, so that the thermal fatigue characteristics are not sufficient for Type 429. In response to the above problem, Nb is added with Cr-containing steel to improve high temperature proof stress, or SUS444 (19Cr-0.2Nb-1.8Mo) specified by 098107277 3 200946694 JIS G4305, and Nb is added. The ferrite-grained stainless steel of Mo, W, and the like have been developed (for example, refer to Japanese Laid-Open Patent Publication No. 2004-018921). However, due to the unusually high price of rare metal raw materials such as Mo or W, it is required to develop a material having the same heat resistance by using inexpensive raw materials. As a material which is excellent in heat resistance without using Mo or W which is an element of the mulberry, for example, in the manual of WO2003/004714, a ferrite-based iron-based stainless steel for an automobile exhaust flow path member is disclosed. At 10~2〇11^3°/. (:1' steel has been added with ribs: 〇.5〇1^53% or less, (:11: 〇.8 ～2_ 0 mass%, V: 0_ 03~0· 20 mass%; and, in Japan And the mass of the steel is added to the steel of the steel. The mass of the steel is added to the steel: Ti. 0. 05~0. 30 mass%, Nb: 0·1〇~〇·6〇mass%, Cu: 〇8~2 〇mass%, B: 0. 0005~〇. 02 mass%; and, in Japanese Patent Laid-Open No. 2000-297355 The invention discloses a ferrite-type iron-based stainless steel for automobile exhaust system parts, which is obtained by adding cu: 1 to 3 maSS% to a steel towel of 15 to 25 years old. The characteristics of the steels are: by adding a However, according to the research by the inventors and the like, it is known that the technique of the above-mentioned Patent Documents 2 to 4 is less than the addition of the Gu reading _, although the refractory property is high, but the oxidation resistance of the steel itself is lowered. Overall, SUS444 is compared with Type429, *,, and naming. It is more sturdy, and it adds Mo in 098107277 200946694. Therefore, there is a problem that the toughness of the base metal deteriorates. SUMMARY OF THE INVENTION An object of the present invention is to provide a technique for preventing reduction in oxidation resistance by addition, whereby the present invention provides a thermal fatigue property and oxidation resistance superiority without adding a high-priced element such as Mo or W, and at the same time ¥429 is equivalent to the above-mentioned fat ferrite. The term "excellent oxidizing and thermal fatigue resistance" as used in the present invention means having the same or higher characteristics as SUS444, specifically, resistance. The oxidation resistance of 'oxidation' at 95G °C's 'thermal fatigue' is based on (10) the thermal fatigue characteristics of the step door cycle, which is equal to or higher than the leg 44. Also, (4) TyPe429 is equivalent to the diligence. In the Charpy impact test, the brittleness rate of the plate is the same as that of - Type 429. The present invention is a type of fermented iron-based stainless steel. Contains c: Please be 5嶋% 〇 below, Si: 0. 5 mass% or less, Μη: 0· 5 mass% or less, p: 〇· 〇4 mass% or less, S: 0.0()6 mass% or less, Cr: 16 〜2〇mass% or less, N: 0. 015 mass% or less, Nb: 0. 3~0. 55 mass%, Ti : 〇. 01 mass% or less, Mo: 0.1 mass% or less, W: 〇·ι affixed below %, Cu: 1〇- ～2. 5 mass%, A1: 0.2~1.2 mass%' remaining part and not - Consist of impurities. Further, the ferrite-based iron-based stainless steel of the present invention is characterized in that: in addition to the above-described component composition, it is further contained from B: 0.003 mass% or less, REM: 〇〇8mass% 098107277 5 200946694 or less, Zr: 0.5 mass%. In the following, v · η ς • The following, c〇: 〇.5mass0/〇 or less and Ni: G.5maSS% or less, H or more. According to the present invention, it is possible to inexpensively obtain the same resistance to the above-mentioned view 44 (^Taga high price M or W and has raw (thermal fatigue characteristics, oxidation resistance), and has a type 429 (representative ingredient Steel, No. 24) Steel No. 24) of the same grade or more is not iron-iron. Therefore, in the automobile exhaust member, the steel of the present invention can be preferably used in the invention. The person and others repeatedly carried out positive __ _ . 社 , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , It is not necessary to add high-priced elements such as w w w, which is excellent in thermal fatigue characteristics and Wei Wei, and adds shame in the range of 0.3 to 0.55 mass%, adding Cu in the crucible and obtaining in the wide temperature zone, U~2.5 hall The scope is improved, and by adding G.2 < high temperature strength, and the thermal fatigue is caused by the addition of Cu, the oxidation resistance is reduced by the soil 1', and A1 is prevented from being controlled within the above appropriate range. Benefit / Therefore, by adding Nb Cu SUS444 equivalent or more to add Mo or Η And ^ f A1 ", fatigue characteristics, oxidation resistance". Further found that the addition of Cu, Al steel is the best way to reduce the amount of Si to reduce the rust resistance of the test, the secret system by ^ ^.5_% or less) and improve 'and, below 098107277 1 ·〇· 01 mass% or less) and with 200946694

The type 429 is equal to or higher than the above, thereby completing the present invention. First, the basic experiment for developing the present invention will be described. By C: 0. 005~0· 007 mass%, N: 0· 004~〇. 〇〇6 mass%, Si. 0. 3 mass%, Μη: 0.2 mass%, Cr: 17 mass%, Nb : 0· 45

Based on the composition of mass% and A1: 0_35 mass%, the steel with various changes in the amount of Cu added in the above composition is melted to form a 50 kg steel block and heated to ii7 〇 °C. Thereafter, hot rolling was performed to form a sheet bar having a thickness of 30 mm x 150 mm. Then, the thin steel sheet is forged to form a steel strip having a profile of 35 mm x 35 Å, annealed at a temperature of 30 ° C - and then machined to produce a thermal fatigue of the size shown in FIG. Thermal fatigue test specimen. Then, as shown in FIG. 2, the restraint-ratio is 0.35 and is 1 〇〇. The thermal fatigue Hfe was measured by a heat treatment cycle of heating and cooling between 〇-850 〇C. Further, for the above thermal fatigue life, the stress is calculated by dividing the load detected by TC by the cross section of the heat parallel portion of the test piece shown in FIG. (stress), the minimum number of cycles when the stress starts to decrease continuously with respect to the stress of the previous cycle, and the number of cycles of 11 cycles corresponds to the number of cycles in which cracks are generated on the test piece. For comparison, the same test was carried out on SUS444 (Cr: 18 mass%-Mo: 2 mass%-Nb: 0.5 mass% steel). Figure 3 shows the results of the above thermal fatigue test. According to the figure, it is known by 098107277 7 200946694 When more than 1.0 mass% of Cu is added, thermal fatigue life equal to or higher than the thermal fatigue life of SUS444 (about 1100 cycles) can be obtained. Therefore, for the improvement of thermal fatigue characteristics, more than 1 mass% of Cu is added. An effective method. Then 'C: 0. 〇〇6 mass%, N: 〇·〇〇7 mass%, Μη: 0·2 mass% ' Si : 0. 3 mass% > Cr : 17 mass% ' Nb : 0. 49 mass% and Cu : 1. 5 mass% of the composition of the composition as a basis for melting in the laboratory A steel having various changes in the amount of A1 added to the above composition is formed, and a steel block of 5 〇kg is formed, and the steel block is hot rolled (h〇t rolling), and the hot rolled sheet is annealed and then cold rolled (cold) R〇ning), finishing annealing 'to form a cold rolled annealed sheet having a thickness of 2 Å. A cold rolled steel sheet obtained as described above was cut out of a test piece of 30 mm x 20 mm, and the test piece was cut out. The upper part is opened with a hole of 4 mm φ, and the surface and the end surface are ground and degreased by using #320 emery paper, and then subjected to the following test. <continuous oxidation test in air > The test piece was kept at a temperature of 95 Torr. The hour in the atmosphere of the atmosphere was measured, and the difference in mass between the test pieces before and after the heating test was measured to determine the oxidation increment per unit area (g/m2). Cyclooxy oxidation test in air> Using the above test piece 'in the atmosphere, the heat treatment was carried out by heat treatment of rCxl rain and 950 Cx25 min, and heat treatment was carried out for 6Q〇 cycle. low quality Since the amount of the release fix has surface sheet 098 107 277 200 946 694 Rust test (503,163,111,011,111:) (8/1112). Further, the heating rate and the cooling rate in the above test were carried out at 5 ° C / sec and 1.5 ° C / sec, respectively. Fig. 4 shows the measurement results of the oxidation increment. Further, Fig. 5 shows the measurement results of the amount of rust peeling. According to these figures, it is possible to obtain an oxidation resistance equivalent to or higher than SUS444 by adding 0.2 mol% or more of A1 (oxidation increase·27 g/m2 or less, rust release amount: 4 g/m2 not full). Then, from C: 0.006 mass%, N: 0.007 mass%, Μη: 0.2 ❹ mass%, Α1: 0·45 mass%, Cr: 17 mass%, Nb: 0·49 mass% ,

Based on the composition of Cu: 1. 5 mass%, a steel having various changes in the amount of Si added in the above composition is melted in the laboratory to form a steel bar of 5 〇kg, and a plate thickness is formed in the same manner as described above. The cold rolled annealed sheet of 2 mm was subjected to a cyclic oxidation test in the same manner as above, and the peeling amount was measured and the results are shown in Fig. 6. From this, it is understood that even if A1 is added in an appropriate amount, if S i exceeds 0.5% 5%, the minerality is lowered and the amount of peeling is increased, so that heat resistance equivalent to that of SUS444 cannot be obtained. The last 'by C: 0. 006~0. 〇〇7 mass%, N: 〇. 〇〇6~〇〇〇7 mass%, Si: 0.3 mass%, Cr: 17 mass%, Nb: 〇 45 mass% and Cu: 1-5 mass% of the composition of the composition, in the laboratory melting - the composition of the above composition of Μη, A1 and Ti with varying amounts of steel, forming 50 kg of steel, After the steel block is hot rolled, the hot rolled sheet is annealed, cold rolled, and finish annealed to form a cold rolled annealed sheet having a thickness of 2 mm. A sub-size Charpy impact test specimen of 098107277 9 200946694 (Charpy impact test specimen) was obtained from the cold rolled annealed sheet, and a Charpy impact test was performed at a temperature of -4 (TC) to determine the brittle fracture rate. The toughness is evaluated. Fig. 7 shows the influence of the Μη content on the toughness when A1: 0.25 mass%, Ti: 0. 006 mass%, and Fig. 8 shows Μη: 0.1 mass%, Ti: The effect of the A1 content on the toughness at 0.005 mass%, and Figure 9 shows the effect of the Ti content on the characterization of A1: 0.25 mass%, Μη: 0·1 mass%. As shown in the figure, in order to obtain the toughness equivalent to or higher than Type 429, it is necessary to be Μη: 0.3 mass% or less, A1: 1. 2 mass% or less, and Ti: mass. 01 mass% or less. The present invention is further carried out in the above findings. The composition of the iron-based stainless steel of the present invention will be described. C: 0. 015 mass% or less c is an element which effectively increases the strength of steel, and when C containing more than 〇〇i5m(10), The reduction in toughness and formability becomes remarkable. Therefore, in the present invention, C is set. 0.015 mass%. In addition, from the viewpoint of ensuring formability, C is preferably as low as possible, preferably 0.008% by mass or less. On the other hand, in order to secure the strength of the member as an exhaust system, c is preferably Please pick it up. It is better for 〇· 〇〇2~0· 〇〇8 fflass%.

Si : 5 mass% or less The system is added as a deoxidizing material. It is preferable to add 〇 · 〇 5 fields (four) or more. Further, Si has an effect of improving the oxidation resistance of the present invention, and the effect of the eighth one cannot be obtained. On the other hand, as shown in Fig. 6, it is found that excessive addition of Si exceeding 098107277 200946694 0·5 mass% cannot be obtained as 0.5 mass% or more with SUS444 or more. This results in a decrease in rust resistance and thus oxidation resistance. Therefore, SiU & Μ η : 0.5 mass % or less Μ η is an element which increases the strength of steel, and is also used in combination. It is preferred to add 0.05_s or more. However, the excess: the agent is easy to generate the r phase at a temperature to lower the heat resistance. 〇 know that if you add more than 山η of the mountain (4), you will not be able to obtain a shirt equal to or equal to the data, so that the purpose of the invention is set to 0.5 massUx. The present invention P: 〇· 04 mass% or less It is desirable to reduce only 〇·04 mass% or less. Preferably, the P system reduces the harmful elements and content of the toughness. Therefore, in the present invention, ρ is set to 0.03 mass% or less. S : 0· 006 mass% or less S system will lower the elongation and r value, adversely affect the formability, and reduce the harmful elements that are the basic characteristics of stainless steel. Therefore, it is desirable to reduce as much as possible. Its content. Therefore, in the present invention, s is set to 〇.006 mass% or less. Preferably, it is set to 〇· 〇〇3 with % or less.

Cr : 16 to 20 mass% lanthanum is an important element for improving the resistance and oxidation resistance of stainless steel. If it is less than 16 mass%, sufficient oxidation resistance cannot be obtained. 098107277 11 200946694 Properties. On the other hand, Cr is an element which hardens and hardens steel by solid solution at room temperature, and particularly when it contains more than 20 mass% of Cr, the above-mentioned disadvantages become remarkable, and it is impossible to obtain the same as Type429. The above processability and toughness. Therefore, in the present invention, Cr is set in the range of 16 to 20 mass%. Preferably, it is set to a range of 16 to 19 mass%. N: 0· 015 mass% or less The N-based element which lowers the toughness and formability of steel, and when it contains N mass% more than 〇.〇15, the above-mentioned reduction becomes remarkable. Therefore, n is set to 〇.〇15 mass% or less. Furthermore, when higher toughness is required, the content of N should be further reduced, preferably less than 〇1〇 mass%.

Nb : 0.3~0·55 mass%

Nb has an effect of forming and fixing C, N and carbonitrides, improving the durability and formability, and resisting the grain boundary corrosion resistance of the welded portion, and having an effect of increasing Gutian's strong production and improving the thermal fatigue characteristics. . In the above-mentioned effect, the double fruit was confirmed when N. 3 mass% or more of Nb was added. On the other hand, the addition of 超·55 mass% is easy to precipitate the Laves phase, and the brittleness is lowered. It is set to a range of 0.3 to 0.55 mass%. Preferably, it is set to a range of 〇 υ 4 to 0.5 mass%. SS/o

Ti : 〇. 01 mass% or less

Ti is more likely to form N-bonds than Nb, and the TiN plays a role of grooving. This makes it possible to make a toughness, especially as shown in Figure 9, when the content of Ti exceeds 〇. 〇丨 ( (10) The play is low. 098107277 12 200946694 Good influence will become significant. Therefore, in the present invention, τ·r丨1 is limited to 0.01 mass% or less.

Mo: 0.1 mass% or less The MQ high-priced element is not actively added in accordance with the gist of the present invention. However, (4) it will be mixed with 〇· ι as a waste from raw materials. Therefore, Mo is set to 〇·1 mass% or less. W ·· 0. 1 mass% or less ❹ W is an element of the same high price as Mo, and it cannot be actively added according to the gist of the present invention. However, it may be mixed with q i mass% or less from waste materials or the like as raw materials. Therefore, w is set to 〇.丨mass% or less.

Gu : 1· 〇~£. 5 mass% . Cu is a very effective element for improving thermal fatigue properties. As shown in Fig. 3', in order to obtain the thermal fatigue resistance equivalent to or higher than SUS444, it is necessary to add 1·0 mass% or more of Cu. However, when added in an amount of more than 2.5 mass%, ruthenium precipitates ε-Cu upon cooling after heat treatment, thereby hardening the steel and causing embrittlement at the time of hot working. More importantly, although the addition of Cu promotes the thermal fatigue resistance, the oxidation resistance of the steel itself is lowered, and overall, the heat resistance is lowered. Although the reason is not fully understood, it is generally considered that the enthalpy in the layer which is directly under the enthalpy formed is thickened, thereby suppressing the re-dispersion which is an element which improves the original oxidation resistance of stainless steel. Therefore, 'Cu is set to 1. 〇~2 5 range of occupational pain. More preferably, it is set to a range of 11 to 1.8 mass%. 098107277 13 200946694 A1 : 0.2~1.2 mass% 糸 It is not essential for improving the resistance of steel with added Cu. In particular, in order to obtain the same oxidation resistance L and 0.2 fflassu:^ as the purpose of the present invention. On the other hand, as shown in Fig. 8, the upper limit is set to 1.2 mass%, and the steel is hardened to be more than 12%. Preferably, it is set to the range of 〇. 3~κ 〇贴(10). ° For the ferrite-based iron-based stainless steel of the present invention, one or two selected from B, awake, Zr, V, =, and Ni may be added in addition to the above-mentioned necessity. More than one species. B : 0· 003 mass% or less B is an effective element for improving the kingness, especially for the second time. This remarkable effect can be obtained by adding 0_0005 mass% or more of B, but when more than 0_003 massW # is added, βΝ❿ is generated to lower the workability. Therefore, when adding Β, it is set to 〇 〇〇 3mass% or less. More preferably, it is set to a range of 0.0005 to 0.002 mass%. _ : 08 mass% or less, Zr : 〇. 5 affixing area _ (rare earth element) and any of Zr are elements for improving the oxidizing property. In the present invention, it is added as needed. In order to obtain the above effects, it is preferable to add k of 〇 01 mass% or more and k of 〇 以上 5 or more. However, the addition of 'REM' more than 〇·08 raass% makes the steel embrittlement, 098107277 14 200946694

The addition of more than 0.5 mass% of Zr 'precipitates & intermetallic, making the steel embrittled. Therefore, in the case of adding _, it is assumed that 〇.〇8 is from the following, and when it is added, it is set to G.5 mass% or less. a V: mass. 5 mass% or less ^ The element which improves the workability and oxidation resistance, especially the effect of improving the emulsification resistance, is preferably added to the 〇15%% or more, more than 〇. 5 When the mass% is excessively added, coarse K is precipitated and the surface properties are deteriorated. Therefore, in the case of adding V, it is preferred that A, 'grinding. 5 mass% or less, preferably 〇 is added. U.4嶋fe circumference is carried out C〇 : 〇· 5 mass% or less is effective to improve the secret elements, preferably added

on. However, Co is a high-priced element, and 〇M is added, and the above effect p is more than 〇·5 mass%, and the above effect is also saturated. Therefore, it is set to 0.5 raass% or less after adding ❿. Better for the factory's range. π · ϋ. 2 maSs%

Ni . 0. 5 mass% or less The element of mrr. In order to obtain the money, (4) is (4) Γ,:. Second, Nl is expensive, and L, this will generate " under (4), so that oxidation resistance is reduced. 5 mass%以下。 In the case of the addition of Ni, preferably set to 0. 5 mass% or less. More preferably, it is set to 〇· 05~0·4 mass%. 098107277 15 200946694 Next, a method of producing the ferrite-based stainless steel of the present invention will be described. The method for producing a stainless steel according to the present invention can be preferably used as long as it is a usual method for producing a ferrite-based stainless steel, and is not particularly limited. For example, it is preferable to melt the steel in a known buckling furnace such as a converter or an electric furnace, or to further refine the steel having the composition of the present invention by secondary refining such as casting refining or vacuum refining, and then use it. The continuous casting method or the agglomerating-blocking calendering method forms the molten steel into a steel sheet (slab), performs hot rolling to form a hot rolled sheet, and anneals the hot rolled sheet as needed, and further performs the hot rolled sheet. Pickling, cold rolling, fine annealing, after pickling and other engineering to form a cold rolled annealed sheet. For the above cold rolling, it may be carried out once or by inserting an intermediate annealing to perform cold rolling for two or more times, and each of the processes of 'cold rolling, finish annealing, and pickling may be cycled. Further, the hot-rolled sheet annealing may be omitted as the case may be. When the glossiness of the surface of the steel sheet is required, the skin rolling may be performed after cold rolling or after finish annealing. Further, preferably, the slab heating temperature before the hot rolling is in the range of 1000 to 1250 ° C. The hot rolling sheet annealing temperature is in the range of 9 〇〇 to ii 〇〇 ° C. The finishing annealing temperature is 900 to 112 ( Scope of TC. The ferrite-based iron-based stainless steel of the present invention obtained as described above is formed into a car or a machine by performing cutting, bending, or manufacturing processing according to the respective applications. Various exhaust system components used in a high temperature environment such as an exhaust pipe of a bicycle, a converter casing, or an exhaust pipe of a thermal power plant. Further, the stainless steel of the present invention used in the above member is not limited to cold rolling. The annealed sheet can also be used as a hot-rolled sheet or a hot-rolled sheet for annealing, and can be used as a rust-removing treatment as needed. Further, the splicing method for assembling the above-mentioned members is not particularly limited and can be used. Ordinary arc welding such as MIG (Metal Inert Gas), MAG (Metal Active Gas), TIG (Tungsten Inert Gas), etc., or resistance welding such as spot welding or seam welding. High-frequency electric resistance welding used in electric seam welding 'high-frequency induction welding, laser welding, etc. [Example 1] 熔 No l to No in the vacuum melting furnace having the composition shown in Table 1 · 27 steel 'and cast to form 5 〇 kg steel block, after forging, divided into two parts. Then, one of the steel blocks divided into two parts is heated to 1170 ° C, then hot rolled to form a plate thickness For the hot-rolled sheet of 5 mm, the hot-rolled sheet is annealed, pickled, and rolled at a reduction ratio of 6〇% at a temperature of 10〇2〇t: • and is subjected to finish annealing at a temperature of 1030 ° C. Then, it was cooled and pickled at an average cooling rate of 20 C/s to form a cold-rolled annealed slab having a thickness of 2 Å and supplied to the following oxidation resistance test and impact test. Further, as a reference The invention steels of the SUS444, Type 429, and WO2003/004714, and the inventions of the Japanese Patent Laid-Open Publication No. 2000-297985, and the Japanese Patent Publication No. 2000-297355 The cold rolled annealed sheets were fabricated in the same manner as above and provided to the same evaluation test. - "continuance oxidation test in air" > Samples of 30 mm x 20 mm 098107277 17 200946694 were cut out from various cold rolled annealed sheets obtained as described above, and 4 mm0 holes were opened in the upper part of the sample. The 32 〇 sandpaper was ground and degreased, and then suspended in a furnace maintained in an atmosphere of heat and maintained for 300 hours. After the test, the mass of the sample was measured, and the difference from the mass before the test measured in advance was determined to calculate yttrium oxide # (g/m2). Furthermore, the actual faces of the test were: owed, and the average oxidation resistance was evaluated using the average value. <Cyclic Circulating Oxidation Test (CyCHc 〇xidati〇n test in air)> A sample of 3〇2χ2〇mm was cut out from the above various cold-rolled annealed sheets, and a hole of 4 mm φ was opened in the upper part of the sample. 'Using #32〇 sandpaper on the surface and end face

After grinding and degreasing, it is subjected to an oxidation test in which the temperature is raised and the temperature is lowered between TC and 95 (TC). In addition, the temperature rise and the temperature drop rate are set to 5°匚/36 (:, 1.5, respectively). ^:/360, hold time at 1〇〇. (: set to 1111] [11, set to 25 min at 950 °c and carry out 600 cycles. In the evaluation of resistance to cyclic oxidation, the sample after the test The mass was measured, and the difference from the mass before the test measured in advance was determined to determine the amount of rust peeling (g/m 2 ). Further, the test was carried out twice, and the cycle resistance was measured by the average value thereof. Evaluation: Charpy impact test> Three kinds of Charpy impact test pieces each forming a v-groove at right angles in the rolling direction were taken from each of the above-mentioned various cold-rolled annealed sheets, and Charpy impact was performed at a temperature of _4 (rc) In the test, the brittle fracture rate was measured, and the average of the three test pieces was determined to evaluate the toughness. 098107277 18 200946694 [Embodiment 2] The remainder of the steel block divided into two parts in Example 1 is called a steel block. After the steel block is heated to U70C, it is hot rolled to form a thick: 3 〇Grandfather width: 15 The thin steel sheet is then forged, and the thin steel sheet is forged to form a steel strip of 35 _□ (see square), which is annealed at a temperature of 1030 C, and then machined to be processed into a size as shown in FIG. The thermal fatigue test piece is provided to the following thermal fatigue test. Further, as a reference example, as in the case of the embodiment, the SUS444, Type 429, and W02003/004714 manuals, and Japanese Patent Laid-Open No. 2006-117985 The invention steel of the Japanese Patent Publication No. 2000-297355 is also prepared in the same manner and supplied to the thermal fatigue test. <thermal fatigue test> In the thermal fatigue test, the limiting ratio is 〇·35, in丨(10)艽 and 85 (the temperature and temperature of rc are cycled to increase and decrease the temperature) to determine the thermal fatigue life. At this time, the heating rate and the cooling rate (co〇nng rate) are set to 〇. °C/sec, 100°C hold time is 2min, 850X: hold time is 5 min. Also, for thermal fatigue life, it is detected at i00°c The load is divided by the test piece soaking The stress is calculated by the cross-sectional area of the parallel portion, and the minimum number of cycles when the stress starts to decrease continuously with respect to the stress of the previous cycle is set. * The atmospheric oxidation test and the atmospheric oxidation test in the above Example 1 are carried out. The results of the Charpy impact test and the results of the heat fatigue resistance test of Example 2 are shown in Table 2. According to Table 2, the steels of the inventions of the invention 098107277 19 200946694 are all equivalent to SUS444. The oxidizing property and the fragile fatigue property have the same or higher toughness as the Type 429, thereby satisfying the object of the present invention. On the other hand, the steel of the comparative example of the steel of the comparative example of the present invention or the reference example of the prior art is not excellent in the oxidation property, the thermal fatigue property, and the toughness of the base material, so that the characteristics which are the object of the present invention cannot be obtained. . (Industrial Applicability) The steel of the present invention is suitable not only for an exhaust system component of an automobile or the like, but also for an exhaust system component or a solid oxide fuel cell of a thermal power generation system requiring the same characteristics. member. 098107277 20

[I 丨 孽 孽 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas mas Lllll B/0. 0009 V/0.051 Co/0.13 B/0.0011 Zr/0. 08 1—H cr&gt; CM rH oos S § s ^ il 1 l 0.008 0.007 | o.oii I 0.005 I 0.006 1 0.007 II 0.007 I 0.008 0.004 I 0.006 I 0.003 0.004 1 0.009 | 1 0.008J | 0.009 I | 0.004 I 1 0.005 I 0.007 G&gt;&lt;=&gt; CD i-H &lt;3&gt; C? 〇· &lt;=&gt; g 〇CZ5 o C5 o ¢=5 sogc=&gt; g &lt;=&gt; s C5 o &lt;=&gt;&lt;=&gt; 〇· C3&gt;sc=&gt; 0.04 £ &lt;=&gt; s C=5 S c =&gt; s C5 1—H c=&gt; c? s CD i—H &lt;=&gt; os (〇C3 C=) CNI o o' C&gt; O' s &lt;=&gt; CZ3 &lt;=? o= 1—( 0.006 0.002 0.006 | o.ooi | 0.003 I | 0.004 I 1 0.007 I 0.004 0.001 I 0.003 I 0.002 0.003 10.006 I | 0.004 I [0.004 I 1 0.009 I 1 0.095 I 0.002 CO inch d 0.41 OO inch ci 0.49 I 0:41 CO ¢=5 0.46 0.45 inch cz&gt; I 0.43 I CD C=&gt; 0.41 ci c^&gt;inch&lt;=&gt;T&quot;H CZ5 1 0.42 I CD θ LO CO CO LO CO 呀03 Oi &lt;NJ CO L〇L〇CO T-H C&lt; i inch 03 CO CO OO CO CO inch s oo c&lt;l oo LO LO inch r—'H 1—&lt; H 1 &lt; 1—H τ·Ή 1—H CZ5 ώ 17.5 LiLl L—17.7 1 16.3 I OO卜^ Lim 17.2 ... —. 17.9 17· 7 18.9 17.4 T—H f— iiLn —17.4” Bu ^ CO Bu· 00 0.004 | | 0.002 I | o.ooi | 0.001 I 0.002 1 1 0.004 I 1 0.002 I 0.003 0.002 1 0.002 I 0.005 0.002 | 0.002 I | 0.004 I | 0.003 ] 1 0.002 1 | 0.003 I 0.002 Ou 0.032 0. 026 | | 0.022 I 0.032 | 0.022 I i 0. 029 I | 0.022 I 0.029 0.026 1 0.031 I 0.027 0.021 | 0.030 I | 0.028 I | 0.028 ] 1 0.020 1 | 0.029 I 0.031 &gt; 4 &lt;=&gt;c=&gt; | 0.48 I C5 OO S &lt;=5 [ML LO CO C5 LO LO d CO C3 0.41 d L62 M9 1 0.72 1 LiaiJ (&gt;3 T&quot;H Μ | 0.13 I oo &lt;NI CD | 0.33 I r__H C=5 | 0.42 | | 0.28 I c=&gt; 0.23 OO | 0.26 | 05 CO ag LQ CO o CO CO c=&gt; LO LO 〇LA41J LO 1—H o CO c=&gt; 05 rH &lt;=&gt; | 0.35 I OO oa c=&gt ; c=&gt; OO CO c&gt; (Nl C&lt;S &lt;=&gt;&lt;=&gt; 0.39 & 3 c=&gt; CT5 Cvl ci i-H c? CO c? | 0.23 | 0.32 oo &lt ;=&gt; | 0.34 cS Ο 0.006 0.005 | 0.005 0.008 | | 0.005 1 | 0.003 I | 0.006 | 0.007 0.008 | 0.004 I 0.006 0.008 | 0.006 I | 0.008 | 0.006 | | o.oii | 0.007 0.005 严^H (NI CO 1 ίο CO OB 03 〇&gt; OO CO 15 CO 1—^ t— 1 H OO tH

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Comparative Example I Comparative Example Comparative Example Comparative Example Invention Example Invention Example Invention Example SUS444 Type429 Reference Example 1 Reference Example 2 | Reference Example 3 1 Chemical composition (mass%) Other I 丨丨i 丨1 V: 0.18 IV :0„ 22 V:0..38 V :0.20 V :0.. 23 丨Ni/0.10 V/0., 10 2 gg ^ s ^ Ni/0.15 0.006 I 0.007 1 1 0.005 I 1 0.008 1 | 0.008 I 0.007 | | 0.005 | | 0.007 | 1 0.006 1 | 0.008 I | 0.008 | 0.010 0.007 0.006 &lt;=? C=5 s C=J s CD c=&gt; s C3 &lt;〇C3 s C=5 (N1 C=3 C=&gt; g C5 s CD &lt;〇d Μ 〇&gt; ι»Η o C=5 s CZ5 § C=&gt;c=&gt; s C=&gt; g CZ5 I 0.05 I s C3 OO rH s CD y-^ o &lt;=5 &lt;〇〇[0.007 I | 0.003 I 1 0.002 I o | 0.003 II 0.008 I | 0.005 1 1 0.004 1 | 0.006 I lo. 003 I | 0.007 I 0.002 g 0.09 〇 〇ο 05 CO c&gt; (=5 0.44 inch C3 &lt;NJ c=&gt; CO &lt;=&gt; 0.45" LO inch CD (NJ LO CD LO &lt;=&gt; CO CO 0.35 0.42 3 〇〇οα Η CO CO 1-H &lt;z&gt; LO oo iH CO &lt;NI iH C&lt;i C&lt;i OO C&lt;l TH i I s C=5 so CO 05 rH 1.36 1.65 ώ 17·5 1 1 ( — I i od &gt; 1 17-9 1 1 17.6 1 LO 卜 · 1-H 卜 · I i σί iH 1 18.2 1 LjmJ LO 17.02 18. 90 | 18.8 | 00 I o.ooi I 0.003 I o.ooi I 0.002 | 0.002 I | 0.003 1 | 0.002 1 I 0.003 I 0.002 1 0.003 I 0.004 0.002 0.003 0.0052 Oh 1 0.027 1 0.031 I | 0.025 1 i 0.030 | | 0.027 I | 0.025 I | 0.024 I | 0.027 | | 0.024 | | 0.031 I | 0.029 I 0.028 0.029 0.005 i '4 0.38 1 CD Eo CD c=&gt; ¢=5 CO 呀 CD CO inch o' CO LO CD In &lt;=&gt; | 0.019 I | 0.028 | &gt;1 i &lt;〇c= 0.002 0.052 C3 CD CV3 CV3 &lt;〇oo CM o LO C&lt;J &lt;〇C&lt;J o 0.34 LO 〇c=&gt; oa inch cz? CO CO s C=3 0.54 g C3 ι-Η 〇·inch CD CO CO ¢=) 05 CsJ &lt;=&gt; CO (NJ CD | 0.09 | 0.32 CD s CO c=&gt; oo o' CM CO C=) 0.46 oa oa &lt;=&gt; 〇1 0.007 1 | 0.00 | 0.006 1 0.005 | 0.007 I [0.003 I | 0.006 1 | 0.007 I | 0.005 I | 0.008 I | 0.007 I 0.008 0.009 0.006 Steel No 03⁄4 §3 cS CO τι

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Steel No Thermal thermal fatigue life (cycle number) Brittle fracture rate at-40 ° C (%) Preparation oxidation increment (g / m2) Bell peel amount (g / m3) 1 21 3 1230 &lt; 5 invention example 2 20 2 1330 &lt;5 invention example 3 21 2 1300 &lt;5 invention example 4 21 2 1500 &lt;5 invention example 5 17 &lt;1. 1212 &lt;5 invention example 6 20 1 1320 &lt;5 invention example 7 21 2 1510 &lt;5 invention example 8 21 2 1260 &lt;5 invention example 9 22 3 1280 &lt;5 invention example 10 20 1 1250 &lt;5 invention example 11 22 3 1290 &lt;5 invention example 12 21 2 1250 &lt;5 Inventive Example 13 80 10 1290 &lt;5 Comparative Example 14 11 &lt;0_ 1 1400 50 Comparative Example 15 14 1 820 &lt;5 Comparative Example 16 18 5 1210 &lt;5 Comparative Example 17 15 &lt;1. 1350 15 Comparative Example 18 15 &lt;0. 1 1300 15 Comparative Example 19 21 10 1210 &lt;5 Comparative Example 20 21 2 1380 15 Comparative Example 21 20 1 700 &lt;5 Comparative Example 22 21 2 1320 20 Comparative Example 23 15 1 1200 &lt;5 Inventive Example 24 15 1 1230 &lt; 5 Inventive Example 25 14 0. 9 1210 &lt; 5 Inventive Example 26 15 1 1240 &lt; 5 Inventive Example 27 15 1 1210 &lt; 5 Inventive Example 28 27 4 1120 10 SUS444 29 51 25 500 &lt;5 Type429 30 &gt; 100 &gt; 100 1480 &lt; 5 Reference Example 1 31 &gt; 100 &gt; 100 1240 &lt; 10 Reference Example 2 32 &gt; 100 &gt; 100 1400 &lt; 10 Reference Example 3 (Note) Reference Example 1: W02003/004714 Invention Steel No. 3, Reference Example 2: Inventive Steel No. of Japanese Patent Laid-Open No. 2006-117985 No. 7, Reference Example 3: Invention Steel No. 5 098107277 23 200946694 of Japanese Patent Laid-Open No. 2000-297355. Fig. 1 is an explanatory diagram of a thermal fatigue test piece. Fig. 2 is an explanatory diagram of temperature and restriction conditions in the thermal fatigue β test. Figure 3 is a graph showing the effect of non-Cu content on thermal fatigue characteristics. Figure 4 is a graph showing the effect of A1 content on oxidation resistance (weight gain by oxidation). Fig. 5 is a graph showing the effect of the A1 content on the oxidation resistance (spoiling of amounts of scale). Fig. 6 is a graph showing the influence of the Si content on the oxidation resistance (the amount of rust peeling). Figure 7 is a graph showing the effect of Μη content on toughness (brittle fracture surface ratio). ‘ Figure 8 is a graph showing the effect of A1 content on the performance (brittle breaking rate). Ο Figure 9 is a graph showing the effect of Ti content on toughness (brittle breaking rate). 098107277 24

Claims (1)

200946694 VII. Patent application scope: 1. A ferrite-rich iron-based stainless steel containing C: 0.105 mass% or less, Si: 0·5 mass% or less, Μη: 0.5 mass% or less, P: 0. 04 Mass% or less, S: 0. 006 mass% or less, Cr: 16 to 20 mass% or less, N: 0·015 mass% or less, Nb: 0. 3 to 0. 55 mass%, Ti: 0.101 mass% The following, Mo: 0.1% mass% or less, W: 0.1 mass% or less, Cu: 1. 0 to 2. 5 mass%, A1: 0·2~1. 2 mass%, the remainder is Fe and not φ is formed by avoiding impurities. 2. For example, the ferrite-based iron-based stainless steel of the first application of the patent scope includes, in addition to the above-mentioned component composition, more than B: 0.003 mass% or less, REM: 0·08 mass% or less, Zr: 0 5 mass% or less, V: 0.5 mass% r or less, Co: 0·5 mass% or less, and Ni: 0. 5 mass% or less selected one or two or more. 25 098107277