JP2004243354A - Ferritic stainless steel welded pipe with excellent spinning processability - Google Patents

Abstract

A ferritic stainless steel welded pipe having excellent spinning workability is proposed.
Preferably, C: 0.020% or less, Cr: 10.0 to 20.0%, Ni: 0.6% or less, Si, Mn, P, S, Al, N in an appropriate range. And a ferritic stainless steel sheet having a composition containing one or two selected from Nb: 0.10 to 1.00% and Ti: 0.10 to 1.00%, Then, the ends of the steel plates are butt-welded to form a weld metal portion having a cross-sectional shape having a penetration depth of 0.9 times or more the thickness of the steel plate and a width on the inner side of the pipe less than the thickness of the steel plate. As a result, even when spinning is performed at an increased processing speed, the probability of breakage of the weld at the pipe end and chipping of the weld is extremely reduced.
[Selection diagram] Fig. 1

Description

【００４２】
【表２】

【００４３】
【表３】

【００４４】
【表４】

【００４５】
【表５】

【００４６】
本発明例はいずれも、極めて優れたスピニング加工性を有する溶接管となっている。一方、本発明の範囲を外れる比較例はスピニング加工性が劣化している。
【００４７】
【発明の効果】
以上のように、本発明のフェライト系ステンレス鋼溶接管は、とくにスピニング加工時の加工速度を高速化した場合であっても良好なスピニング加工性を有し、スピニング加工時の溶接部の破断や欠け落ちを格段に低減することができ、生産能率を格段に向上でき、産業上格段の効果を奏する。また、本発明のフェライト系ステンレス鋼溶接管は、排気系膨径部材用鋼管としても適用できるという効果もある。
【図面の簡単な説明】
【図１】溶接管の溶接金属部の溶込み深さ、溶接金属部の管内面側幅の定義を示す説明図である。
【図２】触媒コンバーターのハウジングの形状の一例を模式的に示す説明図である。
【図３】スピニング加工時に発生する管端の溶接部の破断や、溶接部の欠け落ちの一例を模式的に示す説明図である。
【図４】実施例に使用したスピニング加工装置の構成を模式的に示す説明図である。
【図５】実施例に使用したスピニング加工装置の構成を模式的に示す説明図である。
【符号の説明】
１ 素管
２ スピンドル
３ 把持機構
４ 成形ローラ群
４ａ、４ｂ、４ｃ 成形ローラ
５ 回転台
６ 基台
７ 把持機構
８ 移動テーブル
９ モータケース
１１ａ ハウジングの本体部
１１ｂ ハウジングのコーン部
１１ｃ ハウジングの接続部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ferritic stainless steel welded pipe suitable for automobile exhaust system members, and particularly for exhaust system expanded and contracted members such as mufflers and catalytic converter housings manufactured by spinning steel pipes. The present invention relates to a ferritic stainless steel welded pipe suitable as the above.
[0002]
[Prior art]
2. Description of the Related Art Ferrite stainless steels such as SUH 409L, SUS 429, and SUS 436L, which are excellent in workability and corrosion resistance, have been frequently used for automobile exhaust system members. For example, a housing, a muffler, and the like of a catalytic converter for processing exhaust gas discharged from an automobile engine are examples.
[0003]
FIG. 2 shows a general container shape of the housing of the catalytic converter.
The housing 11 of the catalytic converter has a relatively large-diameter main body 11a for accommodating the catalyst carrier, a relatively small-diameter connection portion 11c connected to the exhaust pipe, and a taper having a gradually decreasing diameter from the main body 11a to the connection portion 11c. And a cone portion 11b.
[0004]
In recent years, the housing 11 of such a catalytic converter is often formed by spinning a raw pipe (welded pipe) having substantially the same diameter as the main body 11a. For example, in Patent Literature 1, a processing roll provided with a drawing roll and a guide roll along a processing axial direction with one end of a raw pipe fitted on a rotating metal core and the other end as a free end, A plurality of pieces are symmetrically arranged around the processing axis on the outer circumference, and the multi-cycle empty drawing process is used to hold the base tube with the guide rolls, squeeze it into a rough shape with the squeezing rolls, and then along the core metal with the squeezing rolls A pipe shrinking method for performing ironing has been proposed.
[0005]
Further, in Patent Document 2, a raw tube is gripped by three rollers, and the rollers are adjusted so that a difference with respect to a geometric spiral angle determined by a relative moving speed in a longitudinal direction of the rollers and a rotation speed of the tube is within 1 degree. A method of manufacturing a tapered steel pipe has been proposed in which the three rollers and the raw tube are relatively moved in the longitudinal direction while being inclined in the longitudinal direction, and the rollers are moved in the radial direction of the tube to taper the raw tube. ing.
[0006]
As described in Patent Documents 1 and 2, a method for forming a tapered tube by spinning is to form a member having a predetermined shape by pressing a plate, and then welding and joining these members to form a tube having a taper. Compared to the method of manufacturing the above, (1) the material yield is good, (2) the integral molding is possible and the reliability of the weld is not reduced, (3) the mold is unnecessary, and (4) the man-hour is reduced. There are advantages such as less. However, the method using spinning has a problem in that the production efficiency is low because spinning requires a relatively long time as compared with the method using press working.
[0007]
For such a problem, for example, in Patent Document 3, a raw pipe is rotated around the pipe axis, and a plurality of forming rollers arranged on the outer circumference of the raw pipe are revolved in a direction opposite to the rotation direction of the raw pipe. A spinning method has been proposed in which a raw tube is moved in the tube axis direction and a forming roll is moved in the radial direction of the raw tube to form a reduced diameter portion in the raw tube. According to the technique described in Patent Document 3, the relative rotation speed is increased, high-speed machining can be performed, and the machining time can be shortened.
[0008]
[Patent Document 1]
Japanese Patent Publication No. 4-46747 [Patent Document 2]
Japanese Patent Application Laid-Open No. H10-24323 [Patent Document 3]
JP 2000-33443 A
[Problems to be solved by the invention]
However, when the steel pipe is subjected to spinning processing to form a reduced diameter portion by applying the technique described in Patent Literature 3, the welded portion W may be broken at the pipe end (FIG. 3A) or FIG. There is a problem that the probability of chipping X of the welded portion W as shown in b) increases.
[0010]
The present invention advantageously solves the above-described problems of the prior art, and even if spinning is performed at an increased processing speed, the probability of breakage of the weld at the pipe end and chipping of the weld is extremely low. An object of the present invention is to propose a ferritic stainless steel welded pipe having excellent spinning workability.
[0011]
[Means for Solving the Problems]
Means for Solving the Problems In order to achieve the above object, the present inventors have conducted a thorough investigation and study on the effects of the microstructure of a weld metal portion and the composition of a steel sheet on the spinning workability of a welded pipe. As a result, the probability of breakage of the weld at the pipe end during spinning and chipping of the weld differs depending on the welding conditions of the welded pipe. It has been found that the probability of breakage of the welded portion and chipping of the welded portion is drastically reduced, and the spinning workability of the welded pipe is significantly improved.
[0012]
Further, even if the cross-sectional shape of the weld metal portion is the same, the probability of chipping of the weld portion varies depending on the steel sheet composition, so that the contents of C, Si, Mn, P, S, Ni and Al are regulated, and Ti and / or Alternatively, it has been found that by using a steel sheet composition containing a certain amount of Nb, the probability of breakage of the welded portion and chipping of the welded portion during spinning is drastically reduced.
[0013]
The present invention has been completed based on the above findings and further studies. That is, the gist of the present invention is as follows.
(1) A ferritic stainless steel welded pipe formed by butt-welding end portions of a ferritic stainless steel sheet processed into a tube, wherein a cross-sectional shape of a weld metal part formed by the welding is the ferritic stainless steel sheet. A ferritic stainless steel welded pipe having excellent spinning workability, having a penetration depth of 0.9 times or more the thickness and a pipe inner side width not more than the thickness of the ferritic stainless steel sheet. (2) In (1), the ferritic stainless steel sheet contains, by mass%, C: 0.020% or less, Si: 1.0% or less, Mn: 1.0% or less, P: 0.040% or less. , S: 0.010% or less, Cr: 10.0 to 20.0%, Ni: 0.6% or less, Al: 0.10% or less, N: 0.020% or less. : 0.10 to 1.00% and one or two selected from Ti: 0.10 to 1.00%, having a composition comprising the balance of Fe and unavoidable impurities. Ferritic stainless steel welded pipe.
(3) In (2), in addition to the above composition, V: 0.01 to 0.5%, W: 0.001 to 0.05%, Co: 0.01 to 0.25 by mass%. % Of a ferritic stainless steel welded pipe containing at least one selected from the group consisting of:
(4) In (2) or (3), one or two members selected from Cu: 3.0% or less and Mo: 3.0% or less by mass% in addition to the above composition. Ferritic stainless steel welded pipe characterized by containing.
(5) The ferritic stainless steel welded pipe according to any one of (2) to (4), further containing B: 0.0002 to 0.0030% by mass in addition to the above composition. .
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described specifically.
The welded pipe of the present invention is a ferritic stainless steel welded pipe formed by butt-welding the ends of a ferritic stainless steel sheet processed into a tubular shape. Preferably, the ferritic stainless steel sheet is a cold-rolled steel sheet. In the welded pipe of the present invention, as shown in FIG. 1 (a), the weld metal formed by welding has a penetration depth of 0.9 times or more the thickness of the steel sheet, and as shown in FIG. 1 (b). In addition, it has a cross-sectional shape having a tube inner surface side width equal to or less than the steel plate thickness. In addition, "the thickness of the steel plate or less" in the width of the weld metal portion on the inner surface of the tube includes the case where no weld metal is formed on the inner surface of the tube, that is, includes zero.
[0015]
Weld metal penetration depth: 0.9 times or more the thickness of the steel plate If the penetration depth of the weld metal is less than 0.9 times the thickness of the steel plate, the strength of the weld will be insufficient and the inside of the pipe will be insufficient. The welding butt portion on the surface side becomes an unpenetrated portion and acts as a notch, and circumferential tensile stress acting on the welded pipe during spinning is concentrated, and fracture occurs at the welded portion at the pipe end. For this reason, the penetration depth of the weld metal is limited to 0.9 times or more the thickness of the steel sheet.
[0016]
Weld metal inner tube width: below the steel plate thickness When the weld metal tube inner width exceeds the steel plate thickness, the weld metal is formed to be convexly large on the tube inner surface and welded to the steel plate base material. Since the vicinity of the boundary with the metal portion (bond portion) is concave, tensile stress in the circumferential direction is concentrated on the bond portion, cracks are easily generated, and chipping of the welded portion is easily generated. In order to prevent the vicinity of the boundary between the steel sheet base material and the weld metal portion from becoming concave, the width of the weld metal portion on the pipe inner surface side is set to zero so that the weld metal portion is not formed on the tube inner surface side. preferable. For this reason, the width of the weld metal part on the inner surface of the pipe is limited to a thickness of the steel sheet including zero or less.
[0017]
Next, the reason for limiting the composition of the ferritic stainless steel sheet constituting the welded pipe of the present invention will be described. Hereinafter, “%” regarding the composition means “% by mass” unless otherwise specified.
C: 0.020% or less C is an element that increases the hardness of the welded part and lowers the toughness, and further lowers the oxidation resistance, which is one of the important characteristics that the automobile exhaust system member should have. . Therefore, in the present invention, it is desirable to reduce as much as possible, but up to 0.020% is acceptable. Therefore, in the present invention, C is preferably limited to 0.020% or less.
[0018]
Si: 1.0% or less Si is an element which increases strength and lowers spinning workability and toughness, and is desirably reduced as much as possible. However, Si is an effective element for improving oxidation resistance. Is limited to 1.0% or less. In addition, it is more preferably 0.12% or more and 0.40% or less.
[0019]
Mn: 1.0% or less Mn is an element effective for improving the strength, and is preferably contained in an amount of 0.15% or more, but if it is contained in a large amount of 1.0% or more, the toughness is reduced. Therefore, Mn is preferably limited to 1.0% or less.
P: 0.040% or less P is an effective element for increasing the strength. However, if it is contained in a large amount exceeding 0.040%, toughness is reduced. For this reason, P is preferably limited to 0.040% or less.
[0020]
S: 0.010% or less S combines with Ti or the like to form a sulfide and becomes a starting point of fracture during spinning. Therefore, in the present invention, it is preferable to reduce as much as possible, but up to 0.010% is acceptable. . For this reason, S is preferably limited to 0.010% or less. Note that the content is more preferably 0.005% or less.
[0021]
Cr: 10.0 to 20.0%
Cr is an element that improves heat resistance and oxidation resistance, and is an essential element in ferritic stainless steel sheets. Such an effect becomes remarkable at a content of 10.0% or more. On the other hand, if the content exceeds 20.0%, the toughness decreases. Therefore, the content of Cr is preferably limited to the range of 10.0 to 20.0%.
[0022]
Ni: 0.6% or less Ni is an element that advantageously contributes to the improvement of toughness. However, if it exceeds 0.6%, the oxidation resistance deteriorates. For this reason, Ni is preferably limited to 0.6% or less.
Al: 0.10% or less Al acts as a deoxidizing agent and combines with N to contribute to the reduction of solute N. For this purpose, Al content of 0.10% or less is sufficient, and in the present invention, Al content is preferably limited to 0.10% or less. In addition, it is more preferably 0.03% or less.
[0023]
N: 0.020% or less N, like C, reduces the toughness of the welded portion, so it is desirable to reduce it as much as possible, but up to 0.020% is acceptable. For this reason, N is preferably limited to 0.020% or less. Note that the content is more preferably 0.010% or less.
One or two kinds of Nb and Ti selected from Nb: 0.10 to 1.00% and Ti: 0.10 to 1.00% all have an effect of enhancing ductility, toughness, and corrosion resistance. , Alone or in combination.
[0024]
Nb and Ti are useful elements that form carbonitrides, reduce solid solution C and N, suppress the formation of carbonitrides of Cr, and enhance ductility, toughness, and corrosion resistance. Nb also has the effect of improving high-temperature strength. Such an effect becomes remarkable when the content of both Nb and Ti is 0.10% or more, but when the content of both Nb and Ti exceeds 1.00%, the toughness is reduced. Therefore, Nb is preferably limited to a range of 0.10 to 1.00%, and Ti is preferably limited to a range of 0.10 to 1.00%. More preferably, Nb is 0.30 to 0.50% and Ti is 0.15 to 0.30%.
[0025]
In the present invention, in addition to the above-described basic composition, the following components can be further contained as needed.
V: 0.01 to 0.5%, W: 0.001 to 0.05%, Co: 0.01 to 0.25% One or more selected from V, W, and Co are Any of these elements is a useful element for improving the resistance to welding cracking of the heat affected zone, and one or more of these elements can be selected and contained as necessary. Such effects are observed when V: 0.01% or more, W: 0.001% or more, and Co: 0.01% or more, respectively, but V: 0.5%, W: 0.05%. , Co: when each exceeds 0.25%, the toughness of the base metal and the weld heat affected zone is reduced. For this reason, it is preferable to limit the respective ranges to V: 0.01 to 0.5%, W: 0.001 to 0.05%, and Co: 0.01 to 0.25%.
[0026]
One or two selected from Cu: 3.0% or less and Mo: 3.0% or less, both of which are elements that improve corrosion resistance, are selected when high corrosion resistance is required. It is preferable to contain them.
Cu improves the corrosion resistance, but if it exceeds 3.0%, there is a risk of hot cracking in hot rolling or the like. For this reason, Cu is preferably limited to 3.0% or less. In addition, more preferably, it is 0.1 to 1.0%.
[0027]
Mo, like Cu, is also an element effective in improving the corrosion resistance. However, if it is contained in excess of 3.0%, not only the spinning workability is reduced but also the toughness of the weld heat affected zone is reduced. For this reason, it is preferable to limit Mo to 3.0% or less. In addition, more preferably, it is 0.4 to 1.3%.
B: 0.0002-0.0030%
B is an element that improves the toughness of the heat affected zone particularly through the improvement of hardenability, and can be contained as necessary. Such effects become remarkable when the content is 0.0002% or more, but when the content exceeds 0.0030%, the hardening increases, and the toughness and workability of the base material and the weld heat affected zone deteriorate. Therefore, when B is contained, it is preferable to limit the content to the range of 0.0002 to 0.0030%. In addition, more preferably, it is 0.0005 to 0.0010%.
[0028]
The balance other than the components described above is Fe and inevitable impurities. As unavoidable impurities, O: 0.015% or less, Mg: 0.0020% or less, and Ca: 0.0020% or less are acceptable.
Next, a preferred method for producing a ferritic stainless steel welded pipe of the present invention will be described.
[0029]
Preferably, after the molten steel having the above-described ferritic stainless steel composition is melted by a known method such as a converter, an electric furnace, or a vacuum melting furnace, the molten steel is subjected to continuous casting or ingot-bulking. (Slab).
The steel material is then heated to a predetermined temperature or hot-rolled directly without heating to obtain a hot-rolled sheet having a predetermined shape. The hot-rolled sheet is usually subjected to hot-rolled sheet annealing, but the hot-rolled sheet annealing may be omitted depending on the application. Next, after the hot-rolled sheet is subjected to the pickling treatment, the hot-rolled sheet becomes a cold-rolled sheet by cold rolling. Next, the cold-rolled sheet is subjected to recrystallization annealing to obtain a ferritic stainless steel sheet (cold-rolled steel sheet) for a welded pipe.
[0030]
This cold-rolled steel sheet is processed into a tubular shape (pipe shape) by die processing by a known method, and the ends of the steel sheet are butt-welded to form a welded pipe. In the present invention, the welding method of the butted portion between the steel plate ends is not particularly limited as long as a weld metal portion having a predetermined cross-sectional shape as described above can be formed, and it is not particularly limited, and arc welding such as TIG welding and plasma arc welding is performed. Method, a laser welding method and the like are suitable. In addition, a welding material is not necessarily required.
[0031]
In addition, the welding heat input is adjusted so that the weld metal portion has the above-described predetermined cross-sectional shape. In the case of arc welding, the welding heat input Q is given by the following equation.
Q = VI / v
Here, Q: welding heat input (J / mm), V: arc voltage (V), I: welding current (A), v: welding speed (mm / s)
Increasing the welding heat input increases the penetration depth and the width of the pipe inner surface side. When the arc voltage V is increased, the welding current I is increased, or the welding speed v is reduced, the welding heat input increases.
[0032]
Hereinafter, the present invention will be described in more detail based on examples.
[0033]
【Example】
Steel having the composition shown in Table 1 was melted in a small vacuum melting furnace to obtain a 100 kg steel ingot. After heating these steel ingots to 1,050 to 1,250 ° C, they were hot-rolled to a finish temperature of 750 to 950 ° C and a winding temperature of 650 to 850 ° C to obtain a hot-rolled sheet of 4.0 mm. A part of these hot rolled sheets was annealed at 800 to 1000 ° C. Next, pickling and cold rolling are sequentially performed on these hot-rolled sheets to obtain cold-rolled sheets having a thickness of 1.2 to 2.0 mm, and then subjected to recrystallization annealing at 850 to 1050 ° C. It was a rolled steel sheet.
[0034]
After cutting each obtained cold-rolled steel sheet, it was bent with a die to form a substantially circular tube, and the ends of the steel sheets were butted. Next, the butt portion was welded by a TIG welding method to obtain a welded pipe of 1.2 to 2.0 mmt × 120 mmφ × 500 mmL. The TIG welding was performed in a shield gas (argon) atmosphere, and at a welding speed of 200 or 200 l / min, as shown in Table 2, while flowing 20 l / min on the outer peripheral surface and 10 l / min on the inner peripheral surface. The test was performed under the conditions of 400 mm / min, an arc voltage of 11 V, and a welding current of 50 to 105 A. By adjusting the welding current, the penetration depth of the weld metal portion and the inner width of the tube were changed.
[0035]
A test piece is sampled from the obtained welded pipe, the cross-sectional shape of the welded metal is observed in a section perpendicular to the longitudinal direction of the welded pipe, and the penetration depth of the welded metal in each welded pipe and the inner width of the pipe are measured. did.
The obtained welded pipe was rotated using the spinning apparatus shown in FIGS. 4 and 5 at a rotational speed of 500 rpm or 1000 rpm, a tightening amount of 2 mm / times, and a relative translation speed of a forming roll of 8000 mm / min. Then, a product having a shape as shown in FIG. 2 was formed.
[0036]
The spinning apparatus shown in FIG. 4 includes a rotation driving unit, a forming roller 4, and a forming roller moving unit (not shown) for moving the forming roller 4. The rotation driving means includes a spindle 2, a gripping mechanism 3 provided on the spindle 2 for gripping the raw tube 1, and a motor (not shown) for rotating and driving the spindle 2. To rotate around the axis CC. The forming roller moving means includes a servo mechanism (not shown) that can be numerically controlled, and moves the forming roller 4 and the base tube 1 relative to each other based on the input data in order to form the base tube 1 into a desired shape. It is configured to be moved in the axis CC direction and the radial D direction. The forming roller 4 is pressed against the raw tube 1 while being moved as indicated by an arrow A in the figure, and spinning-draws the raw tube 1 into a shape having a conical portion.
[0037]
The spinning apparatus shown in FIG. 5 includes parallel moving means for fixedly holding the raw tube 1 and moving the raw tube 1 in the direction of the axis CC, a rotating table 5 having a forming roller group 4, and forming roller rotating / moving means. ing.
The parallel moving means has a base 6 for supporting the raw tube 1 and a holding mechanism 7 for holding the raw tube 1 on a moving table 8, and is driven by a driving means for the moving table 8 (not shown). The tube 1 can be translated in the direction of the axis CC.
[0038]
The forming roller group 4 includes a plurality of forming rollers 4 a, 4 b, and 4 c that impart a predetermined shape to the raw tube 1, and is provided on the turntable 5.
The forming roller rotating / moving means includes a rotating table 5 to which three forming rollers 4a, 4b, and 4c are attached, a motor housed in a motor case 9 for rotating the rotating table 5 around the axis CC, and further rotating. A mechanism embedded in the table 5 for moving the forming rollers 4a, 4b, 4c in a direction D orthogonal to the axis CC by numerical control.
[0039]
The forming roller group 4 revolves by rotating the turntable 5 around its axis CC by means of the forming roller rotation moving means, and the forming rollers 4a, 4b, 4c are moved in the direction D orthogonal to the axis CC. Can be done.
The spinning process was performed on 100 pieces of the welded pipes in each condition, and the number of breaks and chippings of the welded portions was investigated to evaluate the spinning processability. When the forming roll reciprocates relative to the raw tube, the tightening amount indicates an increase in the pressing amount of the forming roll per one reciprocation. The dimensions of the product are as follows: the diameter of the portion 11c is 60 mmφ, the length is 50 mm, and the length of the portion 11b (tapered portion) is 60 mm. The portion 11a has a diameter of 120 mm φ (original size).
[0040]
The spinning processability was as follows: For each of the 100 spinned welded pipes, the number of occurrences of breakage or chipping of the weld was 0 for ◎, 1-2 for ○, 3-9 for △, and 10 or more for It evaluated as x.
Table 2 shows the obtained test results of the spinning workability.
[0041]
[Table 1]

[0042]
[Table 2]

[0043]
[Table 3]

[0044]
[Table 4]

[0045]
[Table 5]

[0046]
Each of the examples of the present invention is a welded pipe having extremely excellent spinning workability. On the other hand, the comparative examples out of the range of the present invention have poor spinning processability.
[0047]
【The invention's effect】
As described above, the ferritic stainless steel welded pipe of the present invention has good spinning workability even when the working speed during spinning is particularly increased, and the welded portion breaks during spinning. Chipping can be greatly reduced, production efficiency can be significantly improved, and industrially significant effects can be achieved. Further, the ferritic stainless steel welded pipe of the present invention has an effect that it can be applied also as a steel pipe for an exhaust system expanded diameter member.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing definitions of a penetration depth of a weld metal part of a welded pipe and a width of a weld metal part on a pipe inner surface side.
FIG. 2 is an explanatory view schematically showing an example of a shape of a housing of a catalytic converter.
FIG. 3 is an explanatory view schematically showing an example of breakage of a weld at a pipe end and chipping of a weld occurring at the time of spinning;
FIG. 4 is an explanatory view schematically showing a configuration of a spinning apparatus used in the example.
FIG. 5 is an explanatory view schematically showing a configuration of a spinning apparatus used in an example.
[Explanation of symbols]
DESCRIPTION OF REFERENCE NUMERALS 1 raw pipe 2 spindle 3 gripping mechanism 4 forming roller group 4a, 4b, 4c forming roller 5 turntable 6 base 7 gripping mechanism 8 moving table 9 motor case 11a housing main body 11b housing cone 11c housing connection

Claims (5)

A ferritic stainless steel welded pipe formed by butt-welding end portions of a ferritic stainless steel sheet processed into a tubular shape, and a sectional shape of a weld metal portion formed by the welding has a thickness of the ferritic stainless steel sheet. A ferritic stainless steel welded pipe excellent in spinning workability, having a penetration depth of 0.9 times or more and a pipe inner side width not more than the thickness of the ferritic stainless steel sheet. The ferritic stainless steel sheet, by mass%,
C: 0.020% or less, Si: 1.0% or less,
Mn: 1.0% or less, P: 0.040% or less,
S: 0.010% or less, Cr: 10.0 to 20.0%,
Ni: 0.6% or less, Al: 0.10% or less,
N: 0.020% or less, Nb: 0.10 to 1.00% and Ti: 0.10 to 1.00%. The ferritic stainless steel welded pipe according to claim 1, having a composition consisting of Fe and unavoidable impurities. In addition to the above composition, 1% selected from V: 0.01 to 0.5%, W: 0.001 to 0.05%, and Co: 0.01 to 0.25% by mass%. The ferritic stainless steel welded pipe according to claim 2, wherein the ferrite-based stainless steel welded pipe contains one or more kinds. 4. The composition according to claim 2, further comprising one or two selected from Cu: 3.0% or less and Mo: 3.0% or less by mass% in addition to the composition. 2. A ferritic stainless steel welded pipe according to item 1. The ferritic stainless steel welded pipe according to any one of claims 2 to 4, further comprising, by mass%, B: 0.0002 to 0.0030% in addition to the composition.

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