WO2009017246A1 - Al-plated steel sheet for exhaust gas passageway members of motorcycles excellent in high-temperature strength and members - Google Patents

Abstract

An Al-plated steel sheet for exhaust gas passageway members of motorcycles which is produced by dipping a substrate steel sheet which contains by mass C: 0.02% or below, Si: 2% or below, Mn: 2% or below, Cr: 5 to 25%, Nb: more than 0.1% to 1%, Ti: 0.3% or below, N: 0.02% or below, and, if necessary, one or more of Ni: 0.6% or below, Al: 0.2% or below, Mo: 3% or below, Cu: 3% or below, W: 3% or below, V: 0.5% or below, Co: 0.5% or below and B: 0.01% or below with the balance consisting of Fe and unavoidable impurities in a molten Al-base plating bath to form a hot-dip plating layer having a mean thickness of 3 to 20μm on the surface of the sheet and which is excellent in high -temperature strength and red scale resistance.

Description

 TECHNICAL FIELD The present invention relates to a high temperature used for an engine exhaust gas passage member of a motorcycle (for example, a muffler, a catalyst carrier, an exhaust pipe, etc.). The present invention relates to an aluminum-based plated steel sheet having excellent strength and red scale resistance, and a motorcycle exhaust gas passage member using the same. Conventional technology The exhaust gas path of motorcycles is shorter than that of automobiles, and it is not uncommon for downstream members such as mufflers to be exposed to temperatures of 400 ° C or higher. Recently, exhaust gas regulations have been tightened, and exhaust gas purification devices using a three-way catalyst are being installed in motorcycles. However, in the case of two-wheeled vehicles, such purification devices are often installed in mufflers. From the viewpoint of heat resistance, heat-resistant ferritic stainless steel such as S U H 4 009 L and S U S 4 3 6 is used for exhaust gas passage members of motorcycles.

 In exhaust gas path members using stainless steel, a reddish brown scale (hereinafter referred to as “red scale”) may occur. This is a phenomenon that is likely to occur in an exhaust gas temperature of 400 to 700 ° C. and in a low oxygen and high water vapor atmosphere. When a red scale develops and mixes with condensed water, it becomes a reddish brown liquid. Condensed water in the exhaust gas path may be discharged from the exhaust port together with the exhaust gas, but the discharge of the reddish brown liquid as described above is very undesirable in appearance.

The muffler in the exhaust gas passage member is a portion where condensed water tends to accumulate. In the case of a typical four-wheeled vehicle, the muffler is rarely exposed to exhaust gas of 400 ° C or higher, and corrosive due to condensed water condensing inside rather than the red scale generated inside the muffler. Is likely to be a problem. However, motorcycles In this case, the muffler is often exposed to 400 ° C or higher as described above, so red scale is generated in the muffler, and the discharge of reddish brown liquid due to the red scale tends to be a problem.

 Patent Document 1 discloses a technique for suppressing the generation of red scale in a stove combustion cylinder or the like by generating an oxide film mainly composed of a Cr-based oxide on the surface in advance. However, since the oxide film is inferior in corrosion resistance, it is necessary to take measures to improve the corrosion resistance of the steel substrate, leading to an increase in material costs. For this reason, it is difficult to apply to exhaust gas passage members. Patent Documents 2 and 3 disclose methods for improving the red scale by using a steel containing a large amount of A 1 Si. However, the formability of such high-A1, Si-added steels is better than that of SUH21, which is a steel grade with good scale resistance of the 18Cr-3A1 system. It is considerably inferior to ferritic stainless steel grades such as L, SUS 4 10 L, SUS 430 LX. For this reason, it is not suitable for exhaust gas passage members of motorcycles.

 On the other hand, steel sheets with Cr-containing steel, such as stainless steel, that have an A1-based finish exhibit good oxidation resistance, and various types of steel that can be used for automobile exhaust system members have been developed (patents). References 4-1 3). Patent Document 1: Japanese Patent Laid-Open No. 200 1-24 0 9 1 1

 Patent Document 2: Japanese Patent Laid-Open No. 200 1-3 1 6 773

 Patent Document 3: Japanese Patent Laid-Open No. 2003-160844

 Patent Document 4: Japanese Patent Laid-Open No. 8-3 1 95 4 3

 Patent Document 5: Japanese Patent Laid-Open No. 5- 1 1 28 5 9

 Patent Document 6: Japanese Patent Laid-Open No. 5-295513

 Patent Document 7: Japanese Patent Application Laid-Open No. Sho 6 1-1 147 8 66

 Patent Document 8: Japanese Patent Application Laid-Open No. Sho 6 1-1 147 8 65

 Patent Document 9: Japanese Patent Laid-Open No. 7-2334 51

 Patent Document 10: JP-A-6 3 -47 3 56

Patent Document 11: Japanese Patent Laid-Open No. 3-277 761 Patent Document 12: Japanese Patent Laid-Open No. 7-1888887

 Patent Document 1 3: Kaihei 8-3256 9 1 gazette Problem to be Solved by the Invention According to the inventors' investigation, the resistance to red scale generation of Cr-containing steel plates such as stainless steel (hereinafter referred to as “red-proof scale”) It is effective to apply the A1 system to improve the performance. However, the inventors conducted a detailed investigation on the above-mentioned known A1 steel plate, and found that these have problems to be improved in order to widely put them into practical use as motorcycle exhaust gas passage members. .

In other words, the A1-based steel sheet of Patent Document 4 is an alloy layer in which Mn or the like is concentrated, and the thickness of the masking layer cannot be said to be sufficiently thin. Therefore, it was judged that the peel-off resistance of the melt-bonded coating layer including the alloy layer was called “plating coating layer”. Since the plated steel sheets of Patent Documents 5 and 6 have a large plating layer thickness, they also have insufficient peel resistance. The steel plates of Patent Documents 7, 8, and 10 can be obtained by applying A 1-type plating after pre-plating with Ni or the like. It cannot be easily adopted for exhaust gas passage members such as mufflers and catalyst carriers, which increase and cost reduction is strongly required. Moreover, the peeling resistance of the plating coating layer when heated to 400 to 700 ° C is not always at a satisfactory level. The steel plate of Patent Document 9 prevents abnormal oxidation at a high temperature of 1 150 to 1250 ° C by using a steel with a rare earth element or Y added as a base material. Due to insufficient adhesion between the plating layer and the base material, the adhesive coating layer tends to peel off after repeated heating and cooling to the 4 ° 0 to 7 ° 0 ° C range. Since the plated steel sheets of Patent Documents 11 and 12 are not sufficiently thin, the plating coating layer has insufficient peel resistance against heating and cooling to a temperature range of 400 to 700 ° C. In addition, “Akaban” described in Patent Document 11 is at room temperature. It is a red coral that is typically seen in ordinary steel that has undergone corrosion, and is different from the “red scale” in this application.

 As described above, the known A1-based stainless steel sheet cannot be said to have sufficient peeling resistance of the plating coating layer when heated to a temperature range of 400 to 700 ° C. Therefore, the conventional A1 type stainless steel sheet is suitable for use in motorcycle mufflers, catalyst supports, etc. used in the temperature range of 400 to 700 ° C. Even if it exhibits red scale properties, peeling of the covering layer will occur during long-term use, and if the corrosion resistance decreases, the red scale resistance will decrease. In other words, it has an anxiety factor in terms of durability. On the other hand, motorcycles equipped with exhaust gas purifying catalysts are also increasing in motorcycles due to stricter exhaust gas regulations. If a catalyst is installed, the exhaust gas temperature rises due to the reaction, and exhaust path members such as mufflers are exposed to higher temperatures. Accordingly, it has become desirable to use materials having higher high-temperature strength than the conventional exhaust gas path members for motorcycles. In addition, steel sheets for exhaust gas members are required to have good formability and low temperature toughness. Furthermore, low cost is also important for practical application.

 The present invention is an A1-based steel plate for use in a motorcycle exhaust gas passage member, and has excellent red scale resistance, formability, and low temperature resistance, and 4 0 to 700 ° C. It is an object of the present invention to provide an A1-based steel plate that is remarkably improved in the peel resistance of the plating coating layer when it is repeatedly heated in the temperature range, and that is inexpensive and has high temperature strength. Means for Solving the Problems As a result of detailed investigations, the inventors have determined that the thickness of the A1-based adhesive layer is controlled to be less than 20 μηι, thereby reducing the peel resistance of the A1-based adhesive layer. Has been found to be remarkably improved, and the present invention has been completed.

That is, according to the present invention, the composition of the steel base is mass%, C: 0.02% or less, S i: 2% or less. Lower, Mn: 2% or less, Cr: 5-25%, Nb: more than 0.1-1%, T i: 0.3% or less, N: 0.02% or less, and further if necessary Ni: 0.6% or less, A1: 0.2% or less, Mo: 3% or less, Cu: 3% or less, W: 3% or less, V: 0.5% or less, Co: 0.5% or less B: One or more of 0.01% or less, with the balance being Fe and steel plates with inevitable impurities,

 The base material contains, in mass%, S i: 3 to 12%. In some cases, one or more of T i, B, S r, Cr, Mn, Mg, and Z r may be 1% or less in total. It is immersed in a molten bath composed of the balance A 1 and the inevitable impurities, then lifted and the amount of plating adhered is adjusted to adjust the surface of the molten adhesive layer with an average thickness of 3 to 20 μπι. A 1-type steel plate for motorcycle exhaust gas path members with excellent red scale resistance formed in the above is provided. Further, according to the present invention, there is provided a two-wheeled vehicle exhaust gas path member having a structure in which the plated steel plate is used as a raw material, and having a structure in which the adhesive layer is in contact with exhaust gas, and a maximum operating temperature is 400 ° C. or more. The

The A1 steel plate of the present invention is excellent in red scale resistance and exfoliation resistance of the metal coating layer when repeatedly heated to a temperature range of 400 to 700 ° C. It is suitable for an exhaust gas passage member (for example, a muffler member) of a motorcycle that is heated and used in a live environment of a red scale. The use of a base steel plate with high high-temperature strength increases the degree of freedom in designing exhaust gas passage members, and this is particularly advantageous for vehicles that have exhaust gas purification catalysts and the exhaust gas temperature rises. In addition, the manufacturing cost can be kept to the same level or lower than that of general A 1 plated stainless steel sheet. Therefore, the present invention can contribute to improving the quality and durability of the exhaust gas passage member of a motorcycle and improving the degree of freedom in design. Preferred Embodiments of the Invention When high Cr steel such as ferritic stainless steel is heated to a high temperature, an oxide generally having a high Cr concentration (Cr-based oxide) is formed on the surface of the steel substrate. Since this Cr-based oxide is highly protective, high Cr steels generally have better high temperature oxidation resistance than low Cr steels. However, even with such high Cr steel, when it is heated in a temperature range of 400 to 700 ° C and in a low oxygen and high water vapor atmosphere, the Cr-based steel is used in the initial oxidation process. It has been found that Fe-based oxides are more easily produced than oxides. This is because, in this temperature range, Cr that is sufficient to cover the surface of the steel substrate with Cr-based oxides cannot be rapidly diffused on the surface. This is presumably because it is preferentially oxidized in a high steam atmosphere. The red scale is composed of oxides with high Fe concentration formed on the surface as described above.

 In order to prevent the formation of red scale, it is only necessary to prevent the formation of Fe-based oxides on the steel substrate surface at the above temperature and atmosphere. One way to achieve this is to apply the A1 system. In this case, A 1 on the surface of the plating layer is rapidly oxidized, and the steel sheet surface is covered with an A 1 oxide film.

 However, according to the investigation by the inventors, the A1-based cover layer is likely to be peeled off from the surface of the steel substrate after repeated heating and cooling to a temperature of 400 to 700 ° C. all right. This is a major factor that does not necessarily show good durability when the conventional A1 steel plate is used for a muffler member of a motorcycle. When a molten A1-based steel sheet is heated to 400-700 ° C, the Fe-A1-based intermetallic compound layer is formed by the mutual diffusion of Fe of the Al steel substrate in the plating layer. Generated and delamination occurs between the intermetallic compound layer and the steel substrate. When the plating coating layer is peeled off in this way, a new red scale is generated from there.

The inventors have studied in detail the technique for preventing the peeling of the plating coating layer of the A1-based steel sheet. As a result, it is possible to reduce the thickness of the A 1 system plating layer in the temperature range of 400 to 700 ° C. and when heated in a low oxygen high water vapor atmosphere. It was found to be extremely effective in suppressing the peeling phenomenon. In this case, it is not necessary to set a special restriction on the composition of the A 1-based plating layer, the structure state, or the composition of the alloy layer. l Thickness of the adhesion layer

 Specifically, in a molten A1-based steel sheet, by suppressing the average thickness of the A1-based plating layer to 20 μηι or less per side, it will stably exhibit excellent peeling resistance. . Here, the average thickness of the A1-based plating layer is a thickness not including the alloy layer. As is well known, the adhesion amount by fusion can be adjusted by the gas wiping method, etc. However, if the plating adhesion amount per side itself is controlled to be 20 μm or less, a part of it reacts with the steel substrate. Therefore, the average thickness of the formed A1-based layer does not exceed 20 μπι. If the operating conditions are such that the alloy layer is formed to be relatively thick, the average thickness of the plating layer may be less than 20 μ ιη even if the plating coverage is set to be slightly thicker than 20 μπιι. There are cases where it is possible. By making the average thickness of the A 1-based adhesive layer less than 15 μπι, the peel resistance is further improved. Accordingly, those having an average thickness of the A 1-based plating layer per side of less than 15 μπι are particularly preferred in the present invention.

 On the other hand, from the viewpoint of preventing red scale, the thicker the A 1-based adhesion layer is, the better. As a result of various investigations, it is necessary to ensure that the average thickness of the A 1-based plating layer per side is 3 μιη or more after using a base steel plate whose composition has been adjusted as described below. If the plating layer becomes thinner than that, it will be difficult to stably prevent the occurrence of red scale. It is more preferable to secure an average thickness of 4 μm or more, and it is even more preferable to set it to 5 μιη or more.

 [Alloy layer thickness]

The alloy layer is brittle compared to the steel substrate and the staking layer. For this reason, the thickness of the alloy layer is preferably thinner in consideration of workability. There is no need to pay particular attention to the use of parts with a low degree of processing, but when severe processing is performed, the average thickness of the alloy layer per side is preferably 5 μm or less, more preferably 4 μm or less. . It is sufficiently possible to manufacture such a thin layer and alloy layer thickness in the melted A1-based mating line using the gas wiping method. When the total thickness of the plating layer thickness and the alloy layer thickness is viewed, the alloy so that the “average thickness of the A1 series plating layer + average thickness of the alloy layer” per side is less than 24 μιη. It is desirable to control the layer thickness. [Composition of A 1 type hot water bath]

 In the A 1 -Si alloy system, as Si is added to A 1, the liquidus temperature decreases, and the eutectic composition is reached around 12 mass% Si. In the present invention, a molten A1-based bath containing 3% by mass or more of Si is used. If the composition is richer than A 1, the bath temperature becomes high, and it becomes difficult to suppress the average thickness of the alloy layer to be thin (for example, 5 μπι or less). In addition, an increase in bath temperature can cause an increase in manufacturing costs. However, if the Si content exceeds 12% by mass, the workability of the A1-based adhesive layer itself is lowered, which is likely to be a problem. Therefore, in the present invention, a melt containing 3 to 12% by mass of Si is used.

A Target steel plate manufactured using a 1-type bath.

 One or more of Ti, B, Sr, Cr, Mn, Mg, and Zr may be contained in the total amount of 1% or less in the A1-type bath. In addition, Fe is included as an inevitable impurity in the bath, but mixing of Fe is allowed within the range of 2.5% by mass or less.

 [Base steel sheet]

The base steel plate used as the plating base plate is a high Cr steel containing 5 to 25 mass% of Cr. Since the corrosion resistance and oxidation resistance are improved by applying the A 1 system, the Cr content at the stainless steel level is not necessarily required, but motorcycle exhaust gas exposed to the environment in contact with condensed water or water vapor is not necessarily required. In order to ensure the corrosion resistance required as a route member and to ensure red scale resistance, at least 5 mass. / Cr content of ₀ or more is required. 10 mass. /. It is more preferable to secure the above Cr content. Corrosion resistance and heat resistance increase with increasing Cr content, but excessive Cr content is uneconomical, and it becomes a factor that hinders formability and low-temperature toughness. r Content is specified in the range of 25 mass% or less.

Nb has the effect of improving the high temperature strength. It also has the effect of improving low temperature toughness when the C and N content is relatively high. In order to obtain these effects sufficiently, the present invention employs a ferritic steel containing Nb exceeding 0.1% by mass. However, according to the research by the inventors, it is clear that Nb contained in the base steel sheet has a factor that impairs the peel resistance of the molten A1-based adhesive layer. Became. As a result of detailed studies, it was found that the Nb content in the base steel sheet can be tolerated up to 1% on the assumption that the average thickness of the A1-based plating layer is 20 μπι or less as described above. It was. Therefore, in the present invention, a base steel sheet containing Nb in the range of more than 0.1 to 1% is used.

Ti is an effective element for fixing C and N in steel, stabilizing the ferrite phase, and improving low temperature toughness and formability. In order to sufficiently bring out these effects, it is preferable to secure a Ti content of 0.05% by mass or more, and more preferably 0.1% by mass or more. However, excessive Ti content hardens the steel, conversely leading to reduced workability and low temperature toughness. Therefore, the Ti content is 0.3 mass. / ₀ The following range limits, 0. It is preferably added in 2 wt% or less.

C, Si, Mn, and N are basic elements contained in steel, C is 0.02 mass% or less, and N is 0.02 mass. It can be in the range of ₀ or less. 'When the content of S i and M n increases, the low temperature fertility decreases, but in the present invention, up to 2% by mass of both S i and M n is allowed. As other elements, Ni: 0.6% or less, A1: 0.2% or less, Mo: 3% or less, Cu: 3% or less, W: 3% or less, V: 0.5% In the following, one or more of Co: 0.5% or less and B: 0.01% or less may be contained. However, if the content of these elements exceeds the above-mentioned regulations, the formability and low temperature toughness are adversely affected. May be affected. The inevitable impurity P is allowed up to about 0.1 mass%, and S is allowed up to about 0.03 mass%.

 〔Production method〕

The base steel sheet can be manufactured by a general steel sheet manufacturing process, and the manufacturing method is not particularly specified. For example, a cold-rolled steel sheet with a pickled finish can be used as the base material. After the surface of the base steel sheet is activated, it is pulled up after being immersed in a molten A1-type bath and the amount of plating is adjusted. As a result, the molten A1-based steel sheet of the present invention can be produced. In addition, a steel plate that has been Fe pre-plated to improve plating properties can be used as the base steel sheet. The base steel sheet is passed through a continuous melting squeeze line in the state of a steel strip, so that stable melting A 1 series Can produce mass steel sheets. As for plating conditions, it is important to control the line speed and wiping conditions so that the average thickness of the plating layer is 20 μ ιη or less per side, but otherwise conventional conditions can be used. . The obtained plated steel sheet is processed into an exhaust gas path member for a motorcycle through a predetermined forming process. Depending on the member, it is formed into a welded pipe and then processed. Examples Ferritic steel types having the compositions shown in Table 1 were melted and cold-rolled annealed steel sheets (pickling finish) having a thickness of 1.2 mm were obtained by a conventional method. All steel types are unavoidable impurities. P is 0.1 mass% or less and S is 0.1 mass. / It is below ₀ . These steel plates were used as the base material (plating base plate), and various melted A 1-type plating was applied. For Nos. 11 and 27, the surface of the cold-rolled annealed steel sheet was Fe pre-plated (2 g / m ² ) was used as the base material. In addition, the plating baths of all the examples contain about 1.7% by mass of Fe as an inevitable impurity. Obtained molten A 1 steel plate

By observing the cross section of the (sample) with SEM (scanning electron microscope), the average thickness of the A1-based adhesive layer was determined. At that time, as a result of examining the average thickness of the alloy layer, all of them were 4 μπι or less except for some comparative examples.

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Each test material was evaluated for red scale resistance, peel resistance of the plating coating layer, formability, and low temperature toughness as follows.

 [Red scale resistance]

 A test piece of 25 mm x 35 mm was cut out from the test material, and an oxidation test was performed using the test piece in the following two heating modes. The number of tests was set to each mode n == 3.

 • Continuous heating; Heat continuously for 100 hours at 600 ° C in a nitrogen atmosphere with a dew point of 80 ° C.

 • Cycle heating: “Heating for 30 minutes at 600 ° C in a nitrogen atmosphere with a dew point of 80 ° C (including soaking time of 25 minutes) → air cooling for 5 minutes” is one cycle, and this is repeated 500 cycles.

About the test piece which implemented each heating mode, the presence or absence of reddish brown discoloration was investigated by visual observation. In addition, the increase in oxidation and the decrease in oxidation (scale peeling amount) were measured. n = 3 for all test pieces, (i) the color change of the red-brown is not observed, (ii) and this oxidized amounts is less than ^{0. 2mg / cm 2, (} iii) oxidation weight loss 0. 2mgZcm ² below in In some cases, the specimens that cleared 3 were evaluated as ◯ (good), and the others were evaluated as X (bad).

 [Peeling resistance of plating coating layer]

 A 25 mm x 35 mm test piece was cut out from the test material and used for 600 ° C cycle heating and 700 ° C cycle heating as shown below. The number of tests was each temperature n = 5.

 • 600 ° C cycle heating: “Heating for 30 minutes at 600 ° C in a nitrogen atmosphere with a dew point of 80 ° C (of which soaking time is 25 minutes) → air cooling for 5 minutes” is one cycle, and this is repeated 1 000 cycles.

 • 700 ° C cycle heating; “Heating for 30 minutes at 700 ° C in a nitrogen atmosphere with a dew point of 80 ° C (of which soaking time is 25 minutes) → air cooling for 5 minutes” is one cycle, and this is repeated 1 000 cycles.

About the test piece implemented at each temperature, the presence or absence of peeling of the cover coating layer was investigated by visual observation. 5 each (n = 5) X temperature 2 levels total 10 test specimens for which no plating layer peeling was observed for all 0 specimens, ◯ (good), others (bad) evaluated. In addition, for the specimens that were evaluated as ◯ (good) in the above 100 0 cycle test, the same 6 0 0 ° C cycle heating and 7 0 0 ° C cycle heating were applied. The cycle was carried out. After 200 cycles, 5 samples at each temperature (n = 5) X temperature 2 levels in total 10 test specimens for which no plating coating layer peeling was observed for ◎ (particularly good) It was evaluated.

 [Formability]

 Tensile specimens (JIS No. 13 B) with the rolling direction as the longitudinal direction were prepared from each specimen (melted A 1 type steel plate with a thickness of 1.2 mm), and n = 3 and JISZ 2 2 41 A tensile test according to 1 was performed to measure stretch. The average value of the elongation of n = 3 was defined as the elongation of the specimen. It has been found from various experiments that a material having a thickness of 1.2 mm can be judged to have good formability that can be processed into an exhaust gas passage member for a motorcycle if the elongation is 30% or more. Therefore, the specimens with an elongation of 30% or more were evaluated as ◯ (good) and the others as X (defect).

 (Low temperature toughness)

 A 55 mm x 10 mm test piece was cut out from each specimen (melted A 1-type steel plate with a thickness of 1.2 mm) so that the longitudinal direction was perpendicular to the rolling direction. A notched impact test piece was produced by forming a 2 mm V notch on the surface. According to the definition of J IS Z 2 220, the height is 10 mm, the width is 1.2 mm, the length is 55 mm, and the height below the notch is 8 mm. Using this specimen, a Charpy impact test in accordance with JISZ 2 2 4 2 was conducted. The specimens for which the brittle fracture occurrence temperature was determined to be 150 ° C or lower was ◯ (good). Bad).

These results are shown in Tables 2 and 3. Table 2

 Plating bath composition Plating layer Red scale resistance Plating

 Specimen Low temperature Category Steel No.

 No. Average thickness Continuous Cycle Coating layer Formability

 Toughness

A1 Si Other t m) 'Heating Heating Resistance to separation

 1 XI balance 9.0-4 〇 o ◎. 〇 〇

2 XI balance 4.5-20 ○ o o ○ ○

3 XI balance 4.5-14 ○ ○ ◎ ○ ○

4 XI Remainder 11.5 1 13 ○ ○ ○ ○ ○

5 XI balance 8.8 Ti: 0.15 18 O.

6 XI balance 8.8 Ti: 0.15 11 ○ ○ ○ ○ ○

7 XI balance 9.0 Sr: 0.40 8 〇 〇 ◎ 〇 〇

8 XI balance 8.7 B: 0.25 14 ○ ○ ◎ o ○

9 XI Balance 8.5 10 ○ ○ ○ ○ o

10 XI balance 8.2 B: 0.15 13 ○ o ◎ 〇 〇

11 • X2 balance 9.0-6 〇 〇 ◎ o .〇 '

12 X2 balance 3.9 1 14 ○ ○ ◎ o o

13 X2 Remainder 10.8-19 ○ ○ ○ ○ ○

14 X2 balance 8.9 Ti: 0.13, 9 ○ o ◎ 〇 〇

.15 X2 balance 9.0 Sr: 0.50 .5 o. ○ ◎ ○ ○

16 X2 balance 8.2 Cr: 0.13 10 〇 Ό Ό ◎ 〇 〇

17 X2 balance 8.2 Mn: 0.20 13 ○ o

 Book ◎ 〇 Departure '18' X3 balance 9.0-18 〇 o 〇 〇 o Light 19 X3 balance 8.7 Mg: 0.15 9 〇 o

 Example ◎ 〇 〇

20 X4 Remaining 8.5 Zr: 0.14 14 ○ ○ ◎ ○ ○

21 X4 balance 9.0 1 18 ○ ○ ○ o ○

22 X4 Balance 9.0 1 10 ○ ○ ○ ○ ○

23 X5 balance 9.0 1 11 〇 o ◎ 〇 〇

24 X6 Balance 9.0-8 o ○ ◎ o ○

25 X7 Remaining 9.0 1 19 ・ ○ ○ ○ ○ ○

26 X7 balance 9.0-9 〇 〇 ◎ 〇 o

27 X8 Remaining 9.0-14 ○ ○ ◎ ○ ○

28 X9 balance 9.0 1 20 ○ ○ o o ○

29 X9 Remaining '9.0-10 ○ ○ ○ ○ ○ ○

30 X10 balance 9.0-8 ○ ○ ◎ ○ o

31 XII Remaining 9.0-13. 〇 〇 ◎ 〇 〇

32 X12 Remaining 9.0-10 ○ ○ ○ ○ ○

33 X13 balance 9.0-7 〇 〇. ◎ 〇 〇

34 X14 balance 9.0 1 17 ○ ○ o ○ ○

35 X14 balance 9.0-8 o ○ ◎ ○ ○

36 X15 Remaining 9.0-13 ○ ○ ◎ ○ ○ Table 3

 Underline: Outside the scope of this invention

As can be seen from Table 2, all of the examples of the present invention in which the average thickness of the A1-based adhesive layer is in the range of 3 to 20 μιη are excellent in red scale resistance and peeling resistance of the adhesive coating layer. showed that. In particular, those having an average thickness of less than 15 μηι exhibited even better peel resistance.

 In contrast, Nos. 52 and 54, which are comparative examples, were inferior in red scale resistance due to the average thickness of the A1-based adhesive layer being too thin. Nos. 51, 53, 55, and .56 were inferior in the peel resistance of the plating coating layer because the average thickness of the A1-based plating layer was greater than 20 μπι. In No. 57, the Nb content of the base steel sheet was too high, so that the peel-off resistance of the covering layer was inferior. Nos. 58, 59, 60 and 62 were inferior in formability and low temperature toughness due to the too high Cr, Ti, Mo and Cu contents of the base steel sheet. . No. 61 was inferior in red scale resistance due to the Cr content of the base steel sheet being too small.

Claims

The scope of the claims 1. By mass%, C: 0.02% or less, Si: 2% or less, Mn: 2% or less, Cr: 5-25%, Nb: more than 0.1-1%, Ti: 0. 3% or less, N: 0.02% or less, steel sheet consisting of the balance Fe and unavoidable impurities as a base material,  The substrate is dipped in a hot dipping bath composed of Si: 3 to 12%, balance A1 and unavoidable impurities in mass%, and then pulled up, and the average thickness is adjusted to 3 to For motorcycle exhaust gas path members with excellent red scale resistance with a 20 μπι adhesive layer on the surface A 1 series steel plate. 2. The steel plate of the base material is further M 1: 0.6% or less, A 1: 0.2% or less, Mo: 3% or less, Cu: 3% or less, W: 3% or less, V: 0.0. The exhaust gas path member for motorcycles having excellent red scale resistance according to claim 1, which contains one or more of 5% or less, Co: ◦ .5% or less, B: 0.01% or less 1 series steel plate. 3. The molten bath according to claim 1 or 2, further comprising one or more of Ti, B, Sr, Cr, Mn, Mg, and Zr in a total range of 1% or less. A 1-type steel plate for motorcycle exhaust gas passage members with excellent red scale resistance described in 1. 4. A motorcycle exhaust gas passage section having a structure in which the plated steel sheet according to any one of claims 1 to 3 is used as a raw material, and the adhesive layer is in contact with exhaust gas, and the maximum operating temperature is 400 ° C or higher. Wood.