JP2021123790A - Ferritic stainless steel sheet for thin-walled tube and thin-walled tube made from the same - Google Patents

Abstract

To provide a ferritic stainless steel sheet having good weldability and good brazability and suitable for a thin-walled tube.SOLUTION: The ferritic stainless steel sheet for a thin-walled tube has a component composition containing, by mass%, C:0.001 to 0.015%, Si:0.01 to 0.80%, Mn:0.01 to 0.40%, P:0.04% or less, S:0.01% or less, Al:0.001 to 0.010%, Cr:18.0 to 24.0%, Ti:0.010% or less, Nb:0.05 to 0.40%, N:0.001 to 0.015%, O:0.0050% or less, and satisfies the following formula (1), Al/O<4.0...(1), and the balance is composed of Fe and inevitable impurities. In Formula (1), Al and O represent the content (mass%) of each element.SELECTED DRAWING: None

Description

The present invention relates to a ferritic stainless steel sheet for thin-walled pipes and a thin-walled pipe using the same, and particularly to a ferritic stainless steel plate for stainless steel thin-walled pipes which can be a substitute for copper pipes in applications where copper pipes have been conventionally used. ..

In recent years, the demand for copper for electric wires and conducting wires has increased against the backdrop of increasing demand for electric power infrastructure in emerging countries and the shift to EVs for automobiles, and the supply and demand of copper has continued to be tight. Demand for copper is expected to increase in the future, and reducing the amount of copper used in response to soaring copper prices has become an important issue.

As a performance peculiar to copper, there is good electrical conductivity. It is not easy to replace copper with other materials for electric wires and conducting wires that utilize this characteristic. On the other hand, copper pipes used as pipes for flowing water and heat media used in gas water heaters and electric water heaters are being replaced with other materials, especially ferritic stainless steel.

The metal pipe used for piping is required to have corrosion resistance, weldability, and brazing property. With regard to corrosion resistance, it is sufficient to select an appropriate ferritic stainless steel that is superior to copper, so there is no problem in replacing copper. On the other hand, weldability and brazing property are generally inferior to ferritic stainless steel, so improvement is required.

As a ferritic stainless steel having excellent weldability, for example, Patent Document 1 discloses a ferritic stainless steel having excellent weldability in which Ca is concentrated within a range of 20 nm or less on the surface layer.

As a ferritic stainless steel having excellent brazing property, for example, Patent Document 2 discloses a ferritic stainless steel for brazing in which the Al and Ti contents are strictly limited. Further, Patent Document 3 discloses a ferritic stainless steel having excellent brazing property, which defines the thickness of the surface film and the cation fractions of Cr, Si, and Al.

However, even with these ferritic stainless steels, it has been difficult to achieve both good weldability and brazing property.

Japanese Unexamined Patent Publication No. 2009-91654 Japanese Unexamined Patent Publication No. 2011-157616 International Publication No. 2014/157104

Good weldability and good brazing property are required to replace copper with ferritic stainless steel, but as described above, conventional stainless steel is sufficient to achieve both weldability and brazing property. Sometimes it wasn't.

An object of the present invention is to provide a ferritic stainless steel sheet which has good weldability and good brazing property and is suitable for thin-walled pipes.

Good weldability and good brazing property are required to replace copper with ferrite stainless steel. In the present invention, a diligent study was made on both weldability and brazing property.

Generally, a copper plate having a thickness of 0.8 to 2.0 mm is used for the copper tube. In order to obtain the same degree of bendability as this copper tube, a stainless steel plate having a plate size of about 0.6 mm is used for the thin-walled stainless steel tube. However, when manufacturing a pipe using a thin stainless steel plate, there is a problem that welding defects occur due to melt-through in pipe-making welding. Therefore, as a result of diligent studies, it was found that when the O concentration in stainless steel becomes 0.0050% or less, the convection of the welding molten pool changes, and welding defects are unlikely to occur even in pipe-making welding in thin-walled pipes. That is, it was clarified that if a ferrite stainless steel sheet having an O of 0.0050% or less is used, a stainless steel sheet for thin-walled pipes having good weldability can be obtained.

Subsequently, the brazing property of Ni brazing was examined. In the present invention, since O in the steel is extremely reduced, in general, the element existing in the steel as a compound with O tends to be present in the solid solution state. Among them, in particular, solid solution Al forms an oxide film on the surface during the brazing treatment and reduces the brazing property. Therefore, in the present invention, the reduction of Al by strict control is performed in order to obtain good brazing property. I found it necessary. As a result of diligent studies, when the relationship between the Al content (mass%) and the O content (mass%) in the ferrite stainless steel satisfies Al <4.0 × O, the ferritic stainless has good brazing properties. It became clear that a steel plate could be obtained.

From the above results, we have invented a ferritic stainless steel sheet having good weldability and brazing property, which is suitable for thin-walled pipes. That is, the gist of the present invention is as follows.

[1] By mass%,
C: 0.001 to 0.015%,
Si: 0.01 to 0.80%,
Mn: 0.01 to 0.40%,
P: 0.04% or less,
S: 0.01% or less,
Al: 0.001 to 0.010%,
Cr: 18.0-24.0%,
Ti: 0.010% or less,
Nb: 0.05 to 0.40%,
N: 0.001 to 0.015%,
O: A ferritic stainless steel sheet for thin-walled pipes containing 0.0050% or less, satisfying the following formula (1), and having a component composition in which the balance is composed of Fe and unavoidable impurities.
Al / O <4.0 ... (1)
However, Al and O in the formula (1) indicate the content (mass%) of each element.
[2] The composition of the components is mass%, and further
Ni: 0 to 3.00%,
Mo: 0-3.00%,
Cu: 0-1.00%,
W: 0 to 0.50%,
Co: The ferrite-based stainless steel sheet for thin-walled pipes according to [1], which contains one or more selected from 0 to 0.50%.
[3] The composition of the components is mass%, and further
V: 0 to 0.50%,
Zr: 0-0.50%,
REM: 0-0.10%,
B: The ferrite-based stainless steel sheet for thin-walled pipes according to [1] or [2], which contains one or more selected from 0 to 0.010%.
[4] A thin-walled pipe made of the ferrite-based stainless steel plate for thin-walled pipe according to any one of [1] to [3] above.

According to the present invention, it is possible to provide a ferritic stainless steel sheet which has good weldability and good brazing property and is suitable for thin-walled pipes.

According to the present invention, a ferritic stainless steel sheet having good weldability and brazing property suitable for use in a stainless steel thin-walled pipe suitable as a substitute for a copper pipe can be obtained.

FIG. 1 is an explanatory diagram for explaining the sagging (dripping amount) of the weld bead in the cross section of the weld bead after pipe forming welding.

The present invention will be described in detail below. In addition,% indicating the content of each element means mass% unless otherwise specified.

C: 0.001 to 0.015%
C is an element inevitably contained in steel. When the content of C is high, the strength is improved, and when the content of C is low, the workability is improved. In order to obtain an appropriate strength as a pipe, it is appropriate to contain 0.001% or more of C. On the other hand, if the content of C exceeds 0.015%, an excessive increase in strength occurs due to the increase in solid solution carbon and the strengthening of precipitation due to the precipitation of Nb carbonitride. In the present invention, an excessive increase in strength is not preferable in order to obtain good workability of the pipe, and therefore, a content of C of 0.015% or less is appropriate. Therefore, the C content was set to 0.001 to 0.015%. The C content is preferably 0.002% or more. The C content is preferably 0.010% or less.

Si: 0.01 to 0.80%
Si is an element useful for deoxidation. In the present invention, it is an important element for reducing oxygen in steel. The effect is obtained with a Si content of 0.01% or more. On the other hand, the excessive content of Si forms an oxide film on the surface of the stainless steel during the brazing treatment, hinders the spread of the brazing, and lowers the brazing property. By setting the Si content to 0.80% or less, it becomes easy to suppress a decrease in brazing property. Therefore, the Si content was set to 0.01 to 0.80%. The Si content is preferably 0.10% or more. The Si content is preferably 0.60% or less.

Mn: 0.01 to 0.40%
Mn is an element inevitably contained in steel and increases its strength. In order to obtain an appropriate strength as a pipe, it is appropriate to contain Mn of 0.01% or more. On the other hand, the content of excess Mn exceeding 0.40% causes an excessive increase in strength due to solid solution strengthening, and it becomes difficult to obtain the good processability of the tube of the present invention. Therefore, the Mn content was set to 0.01 to 0.40%. The Mn content is preferably 0.02% or more. The Mn content is preferably 0.20% or less.

P: 0.04% or less P is an element inevitably contained in steel and is an element that lowers the corrosion resistance of stainless steel. Therefore, the smaller the P content, the more preferable, and the content is 0.04% or less. The P content is preferably 0.03% or less. The lower limit is not particularly limited, but since excessive de-P causes an increase in manufacturing cost, it is preferable that the lower limit of the P content is about 0.01%.

S: 0.01% or less S is an element inevitably contained in steel, but if it is more than 0.01%, the formation of water-soluble sulfides such as CaS and MnS is promoted and the corrosion resistance is lowered. Therefore, the S content was set to 0.01% or less. Although the lower limit is not particularly limited, it is preferable that the lower limit of the S content is about 0.001% because excessive removal of S causes an increase in manufacturing cost.

Al: 0.001 to 0.010%
Al is an element useful for deoxidation, and is an important element for reducing the oxygen concentration in steel in the present invention. The effect is obtained when the Al content is 0.001% or more. On the other hand, if the Al content exceeds 0.010%, an oxide film is likely to be formed on the surface during the brazing treatment, and the brazing property is lowered. Therefore, the Al content was set to 0.001 to 0.010%. The Al content is preferably 0.005% or less.

Cr: 18.0-24.0%
Cr is an important element that determines the corrosion resistance of stainless steel. A Cr content of 18.0% or more is required to obtain corrosion resistance equivalent to that of copper. On the other hand, excessive Cr content lowers processability, so 24.0% or less of Cr content is appropriate. Therefore, the Cr content was set to 18.0 to 24.0%. The Cr content is preferably 19.0% or more. The Cr content is preferably 23.0% or less.

Ti: 0.010% or less Ti is an element that forms an oxide on the surface of stainless steel during the brazing process and reduces the brazing property. If the content of Ti exceeds 0.010%, the brazing property is significantly reduced. Therefore, the Ti content was set to 0.010% or less. The Ti content is preferably 0.008% or less. In order to regulate the upper limit of the Ti content in this way, it is not enough to simply not add Ti as a raw material, and it is necessary to strictly regulate the Ti content of the dissolved raw material. When scrap is used as the melting raw material, it is preferable to use scrap that does not contain Ti. Furthermore, it is necessary to strictly control the condition of the furnace when steel is discharged. If Ti oxide remains in the furnace (furnace wall), the Ti oxide may be reduced depending on the composition of the molten steel, and the molten steel may inevitably contain more than 0.010% of Ti. be. The Ti oxide of the furnace wall is generated when the Ti-containing steel (steel having a Ti content of about 0.1% or more in the steel) is discharged. Therefore, when producing steel having the component composition of the present invention (steel of the present invention), use a furnace that has never produced Ti-containing steel, or immediately before that, use a steel that does not contain Ti (in steel). (Steel with a Ti content of less than 0.1%) must be ejected and then ejected. Since it is industrially impractical to use a new furnace every time for the steel ejection of the present invention steel, it is decided not to eject the Ti-containing steel immediately before the steel ejection of the present invention steel. If the steel output immediately before is not Ti-containing steel, the amount of Ti incorporated into the steel can be regulated to 0.010% or less. Therefore, the steel of the present invention will be released after the steel containing no Ti is released. Preferably, the steel of the present invention is dispensed after the steel containing no Ti is ejected twice or more.

Nb: 0.05 to 0.40%
Nb is an element that preferentially bonds with C and N to suppress a decrease in corrosion resistance due to precipitation of Cr carbonitride. The effect is obtained with a content of Nb of 0.05% or more. On the other hand, excessive Nb content causes precipitation strengthening due to precipitation of fine Nb carbonitrides in addition to increase in strength due to solid solution strengthening, leading to further strength increase. Since the increase in strength becomes remarkable when the content of Nb exceeds 0.40%, it is appropriate that the content of Nb is 0.40% or less. Therefore, the Nb content was set to 0.05 to 0.40%. The Nb content is preferably 0.10% or more, more preferably 0.15% or more. The Nb content is preferably 0.35% or less, more preferably 0.30% or less.

N: 0.001 to 0.015%
Like C, N has the effect of increasing the strength of steel by solid solution strengthening. The effect is obtained when the N content is 0.001% or more. On the other hand, if the content of N exceeds 0.015%, an excessive increase in strength occurs due to precipitation strengthening due to precipitation of Nb carbonitride in addition to an increase in solid solution nitrogen. In the present invention, an excessive increase in strength is not preferable in order to obtain good workability of the pipe, and therefore, an N content of 0.015% or less is appropriate. Therefore, the N content was set to 0.001 to 0.015%. The N content is preferably 0.002% or more. The N content is preferably 0.010% or less.

O: 0.0050% or less O (oxygen) is an element that affects the convection direction of the molten pool during welding and changes the weld penetration property. In the present invention, it has been found that in pipe welding with a plate thickness of 0.6 mm or less, when the O content is 0.0050% or less, weld melt-off is suppressed. It is considered that this is because the convection direction of the surface of the molten pool changed outward, so that the penetration in the depth direction was suppressed. Therefore, the O content was set to 0.0050% or less. The O content is preferably 0.0040% or less, more preferably 0.0030% or less. By reducing the O content, the sagging of the weld bead on the inner surface of the pipe after pipe welding can be further reduced, a good welded portion can be obtained, and better weldability can be obtained. Further, since it becomes difficult to reduce the excess O due to the increase in the deoxidizing time, the O content is preferably 0.0005% or more.

Al / O <4.0 ... (1)
In the present invention, O is extremely reduced in order to ensure the pipe forming weldability of the thin-walled pipe. Therefore, as for the state of existence of Al in the steel, the amount of oxide Al is small and the amount of solid solution Al is large as compared with general stainless steel. Since the solid solution Al forms an oxide film on the surface during the brazing treatment and lowers the brazing property, the brazing property is improved even if the Al is reduced to a content that normally does not affect the brazing. Sometimes it was unsuitable. As a result of the examination, it was found that good brazing property can be obtained when the ratio of the Al content (mass%) to the O content (mass%) is less than 4.0, that is, when Al / O <4.0. I found it. Therefore, Al / O <4.0 was set. More preferably, Al / O <3.0.
Al and O in the above formula (1) and the inequality indicate the Al content (mass%) and the O content (mass%), respectively.

The ferritic stainless steel sheet for thin-walled pipes of the present invention (hereinafter, also simply referred to as the ferritic stainless steel sheet of the present invention) preferably contains the above components and has a component composition in which the balance is Fe and unavoidable impurities.

In addition to the above components, the ferrite-based stainless steel sheet of the present invention can further contain one or more selected from Ni, Mo, Cu, W, and Co in the following ranges.

Ni: 0 to 3.00%
Ni is an element that improves the corrosion resistance of stainless steel, and is an element that suppresses the progress of corrosion in a corrosive environment where a passivation film cannot be formed and active dissolution occurs. However, if the content of Ni exceeds 3.00%, stress corrosion cracking occurs, which is not suitable for piping. Therefore, when Ni is contained, the Ni content is set to 0 to 3.00%. The Ni content is preferably 0.10% or more. The Ni content is preferably 2.00% or less.

Mo: 0 to 3.00%
Mo is an element that promotes the repassivation of the passivation film and improves the corrosion resistance of stainless steel. However, when the Mo content exceeds 3.00%, the strength increases and the workability decreases. Therefore, when Mo is contained, the Mo content is 0 to 3.00%. The Mo content is preferably 0.10% or more. The Mo content is preferably 2.00% or less.

Cu: 0-1.00%
Cu is an element that precipitates at the corroded part after the occurrence of corrosion and suppresses the progress of corrosion. On the other hand, if the Cu content exceeds 1.00%, metal Cu inclusions are formed in the steel, which becomes a corrosion starting point and reduces the rusting property. Therefore, when Cu is contained, the Cu content is set to 0 to 1.00%. The Cu content is preferably 0.10% or more. The Cu content is preferably 0.80% or less.

W: 0 to 0.50%
W has the same effect of improving corrosion resistance as Mo. However, the content of excess W exceeding 0.50% increases the strength and lowers the workability. Therefore, when W is contained, the W content is set to 0 to 0.50%. The W content is preferably 0.10% or more. The W content is preferably 0.40% or less.

Co: 0 to 0.50%
Co is an element that improves toughness. However, if Co is contained in excess of 0.50%, the processability is lowered. Therefore, when Co is contained, the Co content is set to 0 to 0.50%. The Co content is preferably 0.01% or more. The Co content is preferably 0.20% or less.

In addition to the above components, the ferrite-based stainless steel sheet of the present invention can further contain one or more selected from V, Zr, REM, and B in the following ranges.

V: 0 to 0.50%
V is an element that suppresses a decrease in corrosion resistance due to precipitation of Cr nitride by forming a VN. However, if the excess V is contained in excess of 0.50%, the workability is lowered. Therefore, when V is contained, the V content is set to 0 to 0.50%. The V content is preferably 0.01% or more. The V content is preferably 0.30% or less.

Zr: 0-0.50%
Zr has the effect of suppressing sensitization by binding to C and N. However, the content of excess Zr exceeding 0.50% lowers the processability and causes an increase in cost because it is a very expensive element. Therefore, when Zr is contained, the Zr content is set to 0 to 0.50%. The Zr content is preferably 0.10% or more. The Zr content is 0.30% or less.

REM: 0-0.10%
REM (rare earth metal: Rare Earth Metals) is an element that improves oxidation resistance. However, the content of excess REM exceeding 0.10% lowers manufacturability such as pickling property and causes an increase in cost. Therefore, when REM is contained, the REM content is set to 0 to 0.10%. The REM content is preferably 0.01% or more. The REM content is preferably 0.02% or less.

B: 0 to 0.010%
B is an element that improves the secondary processing brittleness. However, the content of excess B exceeding 0.010% causes a decrease in workability due to solid solution strengthening. Therefore, when B is contained, the B content is set to 0 to 0.010%. The B content is preferably 0.001% or more. The B content is preferably 0.008% or less.

The method for producing the ferritic stainless steel sheet of the present invention may follow a conventional method, and an example of a suitable production method is shown below.

The method for producing a ferritic stainless steel of the present invention can be preferably used as long as it is basically a normal method for producing a ferritic stainless steel, and is not particularly limited. For example, the steel is melted in a known melting furnace such as a converter or an electric furnace, or further subjected to secondary refining such as ladle refining or vacuum refining to obtain the steel having the above-mentioned component composition of the present invention by a continuous casting method or. Steel pieces (steel slabs) are made by the ingot-lump rolling method. At this time, when scrap is used, it is preferable to select one that does not contain Ti. Further, as the furnace for refining, a new furnace wall is re-covered, or a furnace after steel containing no Ti (Ti content: less than 0.1%) is discharged at least once is used. Further, in order to limit the O content to the scope of the present invention, it is preferable to carry out secondary refining by the VOD method or the AOD method.

Next, the steel slab having the above-mentioned composition of the present invention is hot-rolled to obtain a hot-rolled plate, and the hot-rolled plate is annealed and pickled as necessary. Then, the hot-rolled plate is cold-rolled to obtain a ferritic stainless steel cold-rolled plate. As an example, a stainless steel slab having the above composition is heated to 1100 to 1300 ° C. and then hot-rolled to a plate thickness of 2.0 to 10.0 mm. The hot-rolled steel strip (hot-rolled plate) thus produced is annealed and pickled at a temperature of 900 to 1100 ° C. to remove scale. Then, cold rolling is performed so that the plate thickness is 0.1 to 0.6 mm, and cold rolled sheet annealing is performed at a temperature of 900 to 1100 ° C. After annealing the cold rolled plate, pickling is performed to remove the scale. In the middle of these manufacturing processes, and finally, descaling treatment by shot blasting or bending, grinding / polishing treatment by a grinder or a polishing belt, and skin pass rolling may be performed. Further, the cold-rolled sheet annealing can be referred to as bright annealing. Pickling can be omitted when the brilliant baking is used.

The ferritic stainless steel sheet of the present invention has good weldability and good brazing property, and is particularly suitable for thin-walled pipes. The thickness of the ferrite-based stainless steel sheet of the present invention is preferably 0.6 mm or less, more preferably 0.5 mm or less. The thickness of the ferritic stainless steel sheet of the present invention is preferably 0.1 mm or more, more preferably 0.2 mm or more. According to the ferritic stainless steel sheet of the present invention, good weldability can be obtained by suppressing welding defects due to melt-through even in pipe-forming welding with a plate thickness of 0.6 mm or less.

The tensile strength (TS) of the ferritic stainless steel sheet of the present invention is preferably 360 MPa or more. The TS is preferably 720 MPa or less. The elongation (El) is preferably 20% or more. The tensile strength and elongation can be measured in accordance with JIS Z 2241.

The ferrite-based stainless steel sheet of the present invention is appropriately subjected to processing such as pipe making, welding, and brazing to obtain a thin-walled pipe. The wall thickness of the thin-walled pipe made of the ferrite-based stainless steel plate of the present invention is, for example, 0.6 mm or less. The thin-walled tube of the present invention can be suitably used as a substitute for a copper tube in applications in which a copper tube has been used.

Hereinafter, the present invention will be described in more detail based on Examples.

Stainless steel having the composition shown in Table 1 was vacuum-melted in a laboratory and decomposed and rolled to obtain a sheet bar having a plate thickness of 30 mm. The prepared sheet bar was heated to 1200 ° C. and then hot-rolled to obtain a hot-rolled sheet having a plate thickness of 3.0 mm. The hot-rolled plate was annealed at a temperature of 1050 ° C. under the condition of a soaking time of 60 s. Then, a cold-rolled plate having a plate thickness of 0.5 mm is obtained by cold rolling, and the cold-rolled plate is annealed at an annealing temperature of 1000 ° C. under the condition of a soaking time of 60 s, and then scaled by neutral salt electrolysis and immersion in glass fluoride. Was removed and used as a test material.

(Evaluation of weldability)
A pipe having a length of 800 mm and a diameter of 22 mm was made from the test material. Pipe welding was performed by TIG welding. The welding conditions were a welding speed of 800 mm / min and a welding current of 80 A, and both the inner and outer surfaces of the pipe were shielded with Ar gas. No. 1 shown in Table 1 below. In No. 21, since the O (oxygen) content was outside the range of the present invention, melt-through occurred and the pipe could not be formed (weldability evaluation result: ×). No. For all steel types other than 21, pipe formation was possible, and good weldability was obtained. Furthermore, No. When the cross section of the weld bead after pipe welding was observed for steel types other than 21, No. 21 was observed. In the steel grades 4 and 19, the amount of dripping of the weld bead of 0.05 mm or more was observed in the direction of the inner surface of the pipe (weldability evaluation result: 〇). As shown in FIG. 1, the amount of the weld bead sagging is the maximum length of the welding bead sagging from the straight line (straight line L) connecting the inner surface side ends of the weld bead cross section toward the inner surface of the pipe. .. No. For steel types other than 4 and 19, the amount of dripping of the weld bead of 0.05 mm or more was not observed in the direction of the inner surface of the pipe, and a better welded portion was obtained in which the dripping of the weld bead was further reduced (weldability evaluation result). : ◎). In this weldability evaluation, the weldability evaluation result × was rejected, the weldability evaluation result 〇 was evaluated as passing (excellent in weldability), and ◎ was evaluated as passing (particularly excellent in weldability).

(Brazing property evaluation)
A 50 × 50 mm test piece was collected from the test material and subjected to a wax wetting and spreading test in accordance with JIS Z 3191. The test piece was placed horizontally, 0.1 g of Ni wax BNi-1 (JIS Z 3265) was placed in the center of the surface of the test piece, and brazing heat treatment was performed in a vacuum furnace. The degree of vacuum of the vacuum furnace was ^10-2 Pa, the heating temperature was 1100 ° C., and the soaking time was 10 min. The diameter _{d 0} of the previous brazed diameter _{d b} after brazing of the brazing was measured and the ratio _{(d b / d 0) ×} 100 wax spread rate (%). A brazing spread rate of 130% or more was judged to have good brazing property (passing the brazing property evaluation), and other cases were judged to have failed the brazing property evaluation.

As described above, No. 1 whose O (oxygen) content is outside the scope of the present invention. At No. 21, melt-through occurred and the pipe could not be formed (weldability evaluation result: ×). In addition, No. 1 whose Al content is outside the scope of the present invention. 19. No. The Ti content is outside the scope of the present invention. 20, No. that does not satisfy Al / O <4.0. 22, No. At No. 23, the brazing spread rate was less than 130%, and good brazing property could not be obtained.

From the above results, it was confirmed that according to the present invention, a ferritic stainless steel sheet suitable for thin-walled pipes can be obtained by achieving both good weldability and good brazing property. The ferritic stainless steel sheet of the present invention has good weldability and good brazing property, and is suitable for use in a stainless steel thin-walled pipe which is suitable as a substitute for a copper pipe.

According to the present invention, as an alternative to copper piping, a ferritic stainless steel plate for thin-walled pipes that can be used in applications where copper piping is used, such as gas water heaters, electric water heaters, and air conditioners, can be obtained.

Claims (4)

By mass%
C: 0.001 to 0.015%,
Si: 0.01 to 0.80%,
Mn: 0.01 to 0.40%,
P: 0.04% or less,
S: 0.01% or less,
Al: 0.001 to 0.010%,
Cr: 18.0-24.0%,
Ti: 0.010% or less,
Nb: 0.05 to 0.40%,
N: 0.001 to 0.015%,
O: A ferritic stainless steel sheet for thin-walled pipes containing 0.0050% or less, satisfying the following formula (1), and having a component composition in which the balance is composed of Fe and unavoidable impurities.
Al / O <4.0 ... (1)
However, Al and O in the formula (1) indicate the content (mass%) of each element. The component composition is mass%, and further
Ni: 0 to 3.00%,
Mo: 0-3.00%,
Cu: 0-1.00%,
W: 0 to 0.50%,
Co: The ferrite-based stainless steel sheet for thin-walled pipes according to claim 1, which contains one or more selected from 0 to 0.50%. The component composition is mass%, and further
V: 0 to 0.50%,
Zr: 0-0.50%,
REM: 0-0.10%,
B: The ferrite-based stainless steel sheet for thin-walled pipes according to claim 1 or 2, which contains one or more selected from 0 to 0.010%. A thin-walled pipe using the ferrite-based stainless steel plate for thin-walled pipe according to any one of claims 1 to 3.

Images