JP2787521B2 - Method of manufacturing ferritic stainless steel welded steel pipe with high corrosion resistance - Google Patents
Method of manufacturing ferritic stainless steel welded steel pipe with high corrosion resistanceInfo
- Publication number
- JP2787521B2 JP2787521B2 JP4106134A JP10613492A JP2787521B2 JP 2787521 B2 JP2787521 B2 JP 2787521B2 JP 4106134 A JP4106134 A JP 4106134A JP 10613492 A JP10613492 A JP 10613492A JP 2787521 B2 JP2787521 B2 JP 2787521B2
- Authority
- JP
- Japan
- Prior art keywords
- pipe
- inert gas
- welded
- stainless steel
- packing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
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- Butt Welding And Welding Of Specific Article (AREA)
- Heat Treatment Of Articles (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、Ｃｒを２５重量％以上
含有するフェライト系ステンレス鋼管をオンラインで連
続的に溶接製管する高耐食性フェライト系ステンレス鋼
管の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a highly corrosion-resistant ferritic stainless steel pipe by continuously welding a ferritic stainless steel pipe containing 25% by weight or more of Cr by online welding.
【０００２】[0002]
【従来の技術】近年、スーパーステンレス鋼と呼ばれる
高Ｃｒフェライト系ステンレス鋼が海水熱交換器用管材
等として使用され始めた。このフェライト系ステンレス
鋼はＣｒを２５％以上含有することで高度の耐食性を確
保しており（２９Ｃｒ−４Ｍｏ−２Ｎｉが代表的な成分
系）、その管材は例えばオンライン連続溶接製管により
製造される。2. Description of the Related Art In recent years, high Cr ferritic stainless steel called super stainless steel has begun to be used as a tube material for seawater heat exchangers. This ferritic stainless steel secures high corrosion resistance by containing Cr at 25% or more (29Cr-4Mo-2Ni is a typical component system), and its tube material is manufactured by, for example, online continuous welding pipe. .
【０００３】オンライン連続溶接製管では、周知のとお
り、ラインに供給された帯状の鋼板が管状に成形され、
その突き合わせ部がＴＩＧ溶接等により溶接される。溶
接鋼管は、更にライン出口で所定の長さに切断される。
溶接鋼管がステンレス鋼管の場合は、所定の長さに切断
された鋼管が、光輝焼鈍炉あるいは大気雰囲気バレル炉
等の雰囲気加熱炉により熱処理されて、所定の機械的性
質を付与される。ステンレス鋼管が前述したＣｒ２５％
以上含有の高耐食性フェライト系ステンレス鋼管の場合
も同様の雰囲気加熱で熱処理が行われていた。[0003] In online continuous welding pipe making, as is well known, a strip-shaped steel sheet supplied to a line is formed into a tube.
The butted portion is welded by TIG welding or the like. The welded steel pipe is further cut to a predetermined length at the line outlet.
When the welded steel pipe is a stainless steel pipe, the steel pipe cut to a predetermined length is subjected to a heat treatment in an atmosphere heating furnace such as a bright annealing furnace or an air atmosphere barrel furnace to have predetermined mechanical properties. Stainless steel pipe is the above-mentioned Cr 25%
In the case of the high corrosion-resistant ferritic stainless steel pipe containing the above, heat treatment was performed under the same atmosphere heating.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、雰囲気
加熱では、所定の熱処理温度に達するまでに長時間（例
えば常温から１０４０℃に１００秒）を要し、昇温速度
が遅い。また、均熱後の冷却にも長時間（例えば１０４
０℃から常温に５０秒）を要し、冷却速度が遅い。この
ような緩速度で前述の高耐食性フェライト系ステンレス
鋼管が所定熱処理温度に加熱されると、結晶粒が粗大化
し、延性低下を生じる。また、このような緩速度で冷却
されると、冷却中に炭・窒化物等の金属間化合物が粒界
に多量に析出し、耐食性が劣化する。この現象は、Ｃｒ
２５％以上含有のフェライト系ステンレス鋼管では、特
に顕著で大きな問題となっている。However, in atmospheric heating, it takes a long time (for example, 100 seconds from normal temperature to 1040 ° C.) to reach a predetermined heat treatment temperature, and the rate of temperature rise is slow. In addition, cooling for a long time (for example, 104
It takes 50 seconds from 0 ° C to normal temperature), and the cooling rate is slow. When the above high corrosion resistant ferritic stainless steel pipe is heated to a predetermined heat treatment temperature at such a slow speed, the crystal grains become coarse and the ductility is reduced. Further, when the cooling is performed at such a slow rate, a large amount of intermetallic compounds such as carbon and nitrides precipitate at the grain boundaries during cooling, and the corrosion resistance deteriorates. This phenomenon is caused by Cr
Ferrite-based stainless steel tubes containing 25% or more are a particularly significant problem.
【０００５】なお、前記結晶粒粗大化は、熱処理加熱保
持温度を低温（例えば９５０℃以下）にすれば防止でき
る。しかし、この場合にはχ相の多量析出によって鋼の
脆化を招き、靱性が著しく低下する。従って、Ｃｒ２５
％以上含有のフェライト系ステンレス鋼管に低温熱処理
は採用することができない。[0005] The coarsening of the crystal grains can be prevented by lowering the heat treatment heat holding temperature (for example, 950 ° C or lower). However, in this case, the precipitation of a large amount of the χ phase causes embrittlement of the steel, and the toughness is significantly reduced. Therefore, Cr25
% Low-temperature heat treatment cannot be adopted for ferritic stainless steel tubes containing more than 10%.
【０００６】Ｃｒ２５％以上含有フェライト系ステンレ
ス鋼管の熱処理における第２の問題は、管内面スケール
に伴う経済性悪化である。A second problem in the heat treatment of ferritic stainless steel tubes containing 25% or more of Cr is the deterioration of economic efficiency accompanying the scale of the inner surface of the tubes.
【０００７】この種の高耐食性フェライト系ステンレス
鋼管の大気中熱処理で生じるスケールは、鋼自体が高耐
食性で酸との反応が殆どないため、例えば硝弗酸液によ
る処理でもその除去に約１ケ月を要する。そのため、そ
のスケールの除去には、専らサンドブラスト、グライン
ダー研削、サンド（或いはスコッチ）ペーパーベルター
研削等のメカニカルな除去手段が用いられている。しか
し、このようなメカニカルな除去手段で管内面のスケー
ル除去を行うのは、多大な工数を要し、非能率で工業的
でない。そのため、内面スケールを生じさせないことが
重要となる。The scale generated by heat treatment of this type of high corrosion resistant ferritic stainless steel tube in the air is approximately one month even if the steel itself has high corrosion resistance and hardly reacts with acid. Cost. Therefore, mechanical removal means such as sand blasting, grinder grinding, sand (or Scotch) paper belter grinding, etc. are exclusively used for removing the scale. However, removing the scale of the inner surface of the pipe by such a mechanical removing means requires a large number of steps, is inefficient, and is not industrial. Therefore, it is important not to generate an inner surface scale.
【０００８】この要求に対しては、雰囲気加熱炉、とり
わけ不活性雰囲気炉である光輝焼鈍による熱処理が有利
となる。しかし、光輝焼鈍炉による熱処理でも管内に残
留する空気のために、内面スケールの発生を避け得な
い。これを防止するには管内の残留空気を不活性ガスに
置換すればよいが、管内をガス置換するにしても多大の
工数を要する。つまり、Ｃｒ２５％以上含有のフェライ
ト系ステンレス鋼管の熱処理では、内面スケールを除去
するにしろ発生させないにしろ、工数増大による経済性
悪化を避け得ないのである。To meet this requirement, an atmosphere heating furnace, particularly a heat treatment by bright annealing, which is an inert atmosphere furnace, is advantageous. However, even if the heat treatment is performed in the bright annealing furnace, the generation of the inner surface scale cannot be avoided due to the air remaining in the tube. To prevent this, the residual air in the pipe may be replaced with an inert gas. However, replacing the gas in the pipe requires a large number of steps. That is, in the heat treatment of the ferritic stainless steel tube containing Cr of 25% or more, whether the scale is removed or not generated, it is inevitable that the economical deterioration due to the increase in the number of steps is avoided.
【０００９】このように、Ｃｒを２５％以上含有する高
耐食性フェライト系ステンレス溶接鋼管の熱処理では、
結晶粒の粗大化による延性低下の問題があり、また、内
面スケールに伴う経済性悪化の問題があった。As described above, in the heat treatment of a high corrosion resistant ferritic stainless steel welded steel pipe containing 25% or more of Cr,
There is a problem of a decrease in ductility due to coarsening of the crystal grains, and a problem of a deterioration in economical efficiency due to the inner surface scale.
【００１０】本発明の目的は、熱処理での結晶粒の粗大
化を防ぎ、且つ管内面にスケールを発生させない高耐食
性フェライト系ステンレス鋼管の製造方法を提供するこ
とにある。本発明の別の目的は、管内面スケールの発生
防止に要するコストを低減させることができる高耐食性
フェライト系ステンレス鋼管の製造方法を提供すること
にある。 An object of the present invention is to provide a method for producing a high corrosion resistant ferritic stainless steel pipe which prevents crystal grains from being coarsened by heat treatment and does not generate scale on the inner surface of the pipe. Another object of the present invention is to generate scale on the inner surface of a tube.
High corrosion resistance that can reduce the cost required for prevention
To provide a method for producing a ferritic stainless steel tube
It is in.
【００１１】[0011]
【課題を解決するための手段】これらの目的を達成する
ために、本発明の高耐食性フェライト系ステンレス鋼管
の製造方法は、Ｃｒを２５重量％以上含有するフェライ
ト系ステンレス鋼管をオンラインで連続溶接製管する高
耐食性フェライト系ステンレス溶接鋼管の製造方法にお
いて、成形途中の管内から溶接後の管内にかけて挿入さ
れた不活性ガス供給管に、気密性パッキン及び通気性パ
ッキンを、気密性パッキンが溶接位置より上流側におい
て管状成形を実質的に終了した成形管の内面に密着し、
通気性パッキンが溶接位置より下流側において溶接管を
内面側から保持するように取り付けると共に、不活性ガ
ス供給管の先端部を閉塞して、パッキン間に位置する部
分にノズル孔を設け、溶接製管中にノズル孔から不活性
ガスを排出することにより、管内のパッキン間に不活性
ガスを充満させると共に、その不活性ガスを下流側の通
気性パッキンを通して下流側へ流動させることにより、
溶接部近傍及び溶接部近傍以降の管内に不活性ガスを供
給充満させ、この状態で、前記溶接部より下流側のライ
ン中で、内部に不活性ガスが充満された溶接管を高周波
誘導加熱手段により管全周にわたって１０００〜１１０
０℃に１００℃／秒以上の昇温速度で急速局部加熱し、
均熱後その加熱部を急冷することを特徴とする。In order to achieve these objects, a method for producing a high corrosion resistant ferritic stainless steel pipe according to the present invention is to continuously ferrite stainless steel pipe containing 25% by weight or more of Cr by online welding. In the method for producing a high corrosion resistant ferritic stainless steel welded pipe to be piped, an airtight gasket and a gas permeable gasket are inserted into the inert gas supply pipe inserted from inside the pipe being formed to inside the pipe after the welding, and the gastight packing is moved from the welding position . placed on the upstream side
The tube is substantially adhered to the inner surface of the formed tube which has been substantially finished ,
Breathable packing the Oite welded pipe downstream of the welding position
Attach so as to hold it from the inner surface side , close the tip of the inert gas supply pipe, provide a nozzle hole at the part located between the packings, and discharge the inert gas from the nozzle hole during welding pipe By filling the inert gas between the packings in the pipe, and flowing the inert gas downstream through the downstream gas-permeable packing,
Inert gas is supplied and filled in the pipe near the welded portion and in the vicinity of the welded portion, and in this state, in a line downstream from the welded portion, the welded pipe filled with the inert gas therein is subjected to high-frequency induction heating means. 1000 to 110 over the entire circumference of the pipe
Rapid local heating to 0 ° C at a rate of 100 ° C / sec or more,
After soaking, the heating part is rapidly cooled.
【００１２】図１は本発明法の実施に適した溶接製管ラ
インの概略構成図である。FIG. 1 is a schematic structural view of a welding pipe line suitable for carrying out the method of the present invention.
【００１３】ライン内に供給された鋼板１は、徐々に管
状に成形され、成形を完全に終了した時点で突き合わせ
部が例えばＴＩＧ溶接機２により溶接されて溶接鋼管１
０とされる。成形途中の管内には、上方から支持体３が
挿入されている。支持体３の下端部から下流側へバー４
が延び、その先端は溶接点より下流側の内面ビード消去
位置に達し、ビード消去用のマンドルル５に連結されて
いる。The steel sheet 1 supplied into the line is gradually formed into a tube, and when the forming is completely completed , a butt portion is welded by, for example, a TIG welding machine 2 to form a welded steel pipe 1.
It is set to 0. The support 3 is inserted into the tube in the middle of molding from above. A bar 4 extends from the lower end of the support 3 to the downstream side.
And its tip reaches an inner surface bead elimination position downstream of the welding point, and is connected to a mandrel 5 for bead elimination.
【００１４】バー４には、不活性ガス供給管６が、若干
の間隔をあけて外挿されている。不活性ガス供給管６
は、溶接点の上流側から下流側へかけて延在し、バー４
との間に形成された環状空間の両端は閉塞されている。
この空間には、溶接点より入側の導入管７を通してＡｒ
等の不活性ガスが導入される。導入された不活性ガス
は、不活性ガス供給管６の溶接点近傍に設けたノズル孔
８から不活性ガス供給管６の外面側に排出される。An inert gas supply pipe 6 is inserted into the bar 4 at a slight interval. Inert gas supply pipe 6
Extends from the upstream side to the downstream side of the welding point, and the bar 4
Are closed at both ends of the annular space formed therebetween.
In this space, Ar gas is introduced through the inlet pipe 7 on the inlet side from the welding point.
And the like. The introduced inert gas is discharged from the nozzle hole 8 provided near the welding point of the inert gas supply pipe 6 to the outer surface side of the inert gas supply pipe 6.
【００１５】不活性ガス供給管６の外面には、溶接点を
挟んでその上下流側にパッキン９，１１が装着されてい
る。溶接点より上流側のパッキン９は、例えば複数枚の
ゴムパッキンの間に耐熱性の高いフログラス等のガラス
繊維パッキンを挟んだ気密性パッキンで、ゴムパッキン
の外面が、管状成形を実質的に終了した成形管の内面に
密着して成形管と外管６の間を気密にシールする。溶接
点より下流側のパッキン１１は、例えば複数枚の前記ガ
ラス繊維パッキンの間にワイヤブラシを挟んだ通気性パ
ッキンで、溶接鋼管１０を内面側から保持してその振れ
を抑える。On the outer surface of the inert gas supply pipe 6, packings 9, 11 are mounted on the upstream and downstream sides of the welding point. The packing 9 upstream from the welding point is, for example, an airtight packing in which a glass fiber packing such as Flogras with high heat resistance is sandwiched between a plurality of rubber packings, and the outer surface of the rubber packing substantially completes the tubular molding. The space between the formed tube and the outer tube 6 is hermetically sealed in close contact with the inner surface of the formed tube. The packing 11 downstream from the welding point is, for example, a gas permeable packing having a wire brush interposed between the plurality of glass fiber packings, and holds the welded steel pipe 10 from the inner surface side to suppress the run-out.
【００１６】不活性ガス供給管６のノズル孔８からその
外面側に排出された不活性ガスは、管状成形を実質的に
終了し突き合わせ部間の隙間が殆どない成形管の内面に
密着する気密性パッキン９が上流側にあるため、その上
流側には殆ど逸散しないだけでなく、下流側に設けられ
た通気性パッキン１１の流通抵抗のために、一旦、気密
性パッキン９と通気性パッキン１１の間に溜まることに
より、溶接部近傍の管内側を不活性ガス雰囲気に保持す
る。不活性ガスの排出が更に続けられることにより、そ
の不活性ガスは、大部分が通気性パッキン１１を通って
溶接鋼管１０内を下流側へ流動し、その溶接鋼管１０の
内部を全長にわたって不活性ガス雰囲気に保持する。The inert gas discharged from the nozzle hole 8 of the inert gas supply pipe 6 to the outer surface thereof substantially forms a tubular tube.
Finished and on the inner surface of the formed tube with almost no gap between the butted parts
Since the airtight packing 9 in close contact is on the upstream side, not only the hardly escape to the upstream side, because of the flow resistance of the breathable packing 11 provided on the downstream side, once the airtight packing 9 By accumulating between the gas permeable packings 11, the inside of the pipe near the weld is maintained in an inert gas atmosphere. As the discharge of the inert gas is further continued, the inert gas mostly flows through the gas permeable packing 11 to the downstream side in the welded steel pipe 10 and passes through the inside of the welded steel pipe 10 over the entire length. Keep in gas atmosphere.
【００１７】溶接鋼管１０は、ＴＩＧ溶接機２の下流側
に設けられたベルダー等で外面ビードを除去され、その
更に下流側のマンドレル５のところで、マンドレル５と
これに組み合わされるビードハンマー等により内面ビー
ドを圧壊消去される。マンドレル５は溶接鋼管１０の内
径より小径であり、管内の不活性ガスの流通を阻害しな
い。そして、内外面ビードを除去乃至消去された溶接鋼
管１０は、高周波誘導加熱コイル１２により全周にわた
って急速局部加熱され、更にその下流側に設けた環状の
散水ヘッダー１３から噴出される急冷水により、その加
熱部が急冷される。The outer bead of the welded steel pipe 10 is removed by a beller or the like provided on the downstream side of the TIG welding machine 2, and the inner surface of the welded steel pipe 10 is further removed by a mandrel 5 and a bead hammer combined therewith at a mandrel 5 further downstream. The bead is crushed and erased. The mandrel 5 has a smaller diameter than the inner diameter of the welded steel pipe 10 and does not hinder the flow of the inert gas in the pipe. Then, the welded steel pipe 10 from which the inner and outer surface beads have been removed or eliminated is rapidly and locally heated over the entire circumference by the high-frequency induction heating coil 12, and further quenched by the quench water jetted from the annular watering header 13 provided on the downstream side. The heating part is rapidly cooled.
【００１８】[0018]
【作用】本発明法においては、Ｃｒを２５重量％以上含
有し、且つオンラインで連続溶接製管される溶接鋼管
が、そのライン中で高周波誘導加熱手段により管全周に
わたって急速局部加熱され、均熱後その加熱部が急冷さ
れる。そのため、熱処理における結晶粒の粗大化がな
く、その粗大化による延性低下が防止される。According to the method of the present invention, a welded steel pipe containing 25% by weight or more of Cr and continuously welded and formed on-line is rapidly and locally heated over the entire circumference of the pipe by high frequency induction heating means in the line. After heating, the heating part is rapidly cooled. Therefore, the crystal grains are not coarsened in the heat treatment, and a decrease in ductility due to the coarsening is prevented.
【００１９】ここで、加熱温度が１０００℃未満の場合
は、炭・窒化物等の金属間化合物が粒界に多量析出して
鋼の脆化を招き延性および耐食性が低下する。また、加
熱温度が１１００℃を超えた場合は、結晶粒が急激に粗
大化して延性が低下する。従って、加熱温度は１０００
〜１１００℃とする。昇温速度については、結晶粒の粗
大化を防止するために１００℃／秒以上とする。加熱部
の冷却も、金属間化合物の粒界析出防止のために水冷、
噴霧水冷あるいは強制空冷等による急冷が必要であり、
冷却速度としては５０℃／秒以上が望ましい。均熱時間
については、これが長いと結晶粒の粗大化を招くので、
短時間保持が必要であり、１０秒以内とするのが望まし
い。If the heating temperature is lower than 1000 ° C., a large amount of intermetallic compounds such as carbon and nitrides precipitate at the grain boundaries, causing embrittlement of the steel, resulting in reduced ductility and corrosion resistance. On the other hand, when the heating temperature exceeds 1100 ° C., the crystal grains are rapidly coarsened and ductility is reduced. Therefore, the heating temperature is 1000
１1100 ° C. The rate of temperature rise is set to 100 ° C./sec or more in order to prevent crystal grains from becoming coarse. Cooling of the heating unit is also water-cooled to prevent intergranular precipitation of intermetallic compounds,
Rapid cooling by spray water cooling or forced air cooling is necessary,
The cooling rate is desirably 50 ° C./sec or more. Regarding the soaking time, if this is long, the crystal grains become coarse,
Short-term holding is required, and it is desirable to keep it within 10 seconds.
【００２０】また、前記熱処理においては、溶接鋼管の
内部にＡｒ等の不活性ガスが充満されているので、内面
スケールを生じない。しかも、溶接位置の上流側に気密
性パッキンが設けられ、下流側に通気性パッキンが設け
られているので、管内へ供給された不活性ガスが溶接点
近傍の管内に充満し、溶接部内面を効果的にシールドす
る。そして、両パッキン間に供給される不活性ガスは、
管の上流側および外面側への逸散はほとんどなく、大部
分が管の進行に伴って下流側の通気性パッキンを通過
し、その下流側へ流動することによって消費される。従
って、単位時間当りの管内移動空間容積より若干多目の
不活性ガスを管内に供給しておけば、溶接鋼管１０の内
部は、溶接部近傍の内面側を含め、不活性ガスにより充
満され続ける。不活性ガス中に水素を混合すれば、管内
面の光沢は一層良好となる。なお、Ｃｒを２５重量％以
上含むものではないが、オンラインで製造される溶接鋼
管を連続的に加熱・冷却する際に、成形途中の管内から
溶接点下流側のビード消去位置まで不活性ガス供給管を
挿入し、この不活性ガス供給管の外面側に溶接点上流側
に位置して気密性パッキンを設けることにより、溶接鋼
管内に不活性ガスを流通させる内面シールド技術は、特
開昭５０−１４５３５５号公報及び特開昭５０−１４５
３５７号公報に記載されている。しかし、この技術では
気密性パッキンの下流側に通気性パッキンが組み合わさ
れておらず、溶接点下流側において、溶接鋼管の進行方
向に不活性ガスが放出され続けるだけであるので、溶接
部が十分に内面シールドされないという問題があり、も
し仮に溶接部まで十分な内面シールドを行おうとすると
極めて多量の不活性ガスが必要となる。また、溶接点下
流側で溶接鋼管が内面側から支持されないので、溶接鋼
管の揺れが顕著になり、この揺れが溶接や後述する下流
側での誘導加熱に悪影響を与える。 In the heat treatment, since the inside of the welded steel pipe is filled with an inert gas such as Ar, the inner surface scale does not occur. Moreover, an airtight packing is provided on the upstream side of the welding position, and a gas permeable packing is provided on the downstream side.
The inert gas supplied into the pipe fills the pipe near the welding point , effectively shielding the inner surface of the weld .
You . And the inert gas supplied between both packings is
Dissipation is little to upstream and outer surface of the tube, pass through the breathable packing downstream mostly I accompanied the progress of the tube
And is consumed by flowing downstream . Therefore, if an inert gas slightly larger than the moving space volume in the pipe per unit time is supplied into the pipe, the inside of the welded steel pipe 10 continues to be filled with the inert gas including the inner surface near the welded portion. . If hydrogen is mixed into the inert gas, the inner surface of the tube becomes more glossy. In addition, Cr is 25% by weight or less.
Welded steel manufactured online, not included above
When heating and cooling the tube continuously,
Connect the inert gas supply pipe to the bead elimination position downstream of the welding point.
Insert the upstream side of the welding point into the outer surface side of this inert gas supply pipe.
The airtight packing is located in the
The inner shield technology that allows inert gas to flow through the pipe is
Japanese Patent Application Laid-Open No. 50-145355 and Japanese Patent Application Laid-Open No. 50-145.
357. But with this technology
Combined with air-permeable packing on the downstream side of air-tight packing
The welded steel pipe progresses downstream of the welding point.
The inert gas only continues to be released in the
There is a problem that the part is not sufficiently shielded inside,
If you try to provide sufficient internal shield to the weld
An extremely large amount of inert gas is required. Also, below the welding point
Since the welded steel pipe is not supported from the inner side on the flow side,
The sway of the pipe becomes remarkable, and this sway is caused by welding and
Adversely affects induction heating on the side.
【００２１】溶接鋼管の望ましい成分組成は、Ｃｒ：２
５〜３５％，Ｍｏ：１〜８％，Ｎｉ：３％以下，Ｃ＋
Ｎ：0.０２％以下である。即ち、Ｃｒは２５％未満では
耐食性が不充分であり、３５％超では鋼が脆くなって実
用的でない。Ｍｏは耐孔食性改善目的で添加されるが、
１％未満ではその効果がなく、８％超では鋼が脆くなる
と共にコスト上昇を招き実用的でない。Ｎｉは加工性改
善目的で添加されるが、３％超では金属間化合物の粒界
析出を招いて耐食性が劣化する。Ｃ＋Ｎは炭・窒化物の
粒界析出を抑制する観点から、少ない方がよく、0.０２
％以下とする。なお、上記以外の成分としては、Ｓｉ，
Ｍｎ，Ｐ，Ｓおよびその他の合金元素を、一般のフェラ
イト系ステンレス鋼に含まれる量を含有してなんら問題
はない。The desirable composition of the welded steel pipe is Cr: 2
5 to 35%, Mo: 1 to 8%, Ni: 3% or less, C +
N: 0.02% or less. That is, if Cr is less than 25%, the corrosion resistance is insufficient, and if it exceeds 35%, the steel becomes brittle and is not practical. Mo is added for the purpose of improving pitting corrosion resistance,
If it is less than 1%, the effect is not obtained, and if it exceeds 8%, the steel becomes brittle and causes an increase in cost, which is not practical. Ni is added for the purpose of improving workability. However, if it exceeds 3%, intergranular precipitation of intermetallic compounds is caused to deteriorate the corrosion resistance. From the viewpoint of suppressing grain boundary precipitation of carbon and nitride, C + N is preferably as small as possible.
% Or less. In addition, as components other than the above, Si,
There is no problem if Mn, P, S and other alloying elements are contained in an amount contained in general ferritic stainless steel.
【００２２】[0022]
【実施例】以下に本発明の実施例を説明する。Embodiments of the present invention will be described below.
【００２３】表１（Ａ）に組成を示すＣｒ２５％以上含
有のフェライト系ステンレス鋼板を素材として、図１の
連続溶接製管ラインにより外径２5.４ｍｍ×内径２4.０
ｍｍ×肉厚0.７ｍｍの鋼管を製造した。不活性ガスとし
ては、Ａｒを１５リットル／分供給した。製造された鋼
管の内面スケールの生成状況、結晶粒度および強度を調
査した結果を表２に示す。比較のために、不活性ガスの
供給を行わなかった場合の結果、ライン内熱処理を行わ
ずに製造した鋼管を切断後に光輝焼鈍炉でバッチ熱処理
した場合の結果、表１（Ｂ）に組成を示すＣｒ２５％未
満のフェライト系ステンレス鋼管をバッチ熱処理した場
合の結果も合わせて示す。A ferritic stainless steel sheet containing 25% or more of Cr and having a composition shown in Table 1 (A) was used as a raw material, and the outer diameter was 25.4 mm and the inner diameter was 24.0 by the continuous welding pipe line shown in FIG.
A steel pipe having a thickness of 0.7 mm and a wall thickness of 0.7 mm was manufactured. As an inert gas, Ar was supplied at 15 liter / min. Table 2 shows the results of investigation on the state of formation of the inner surface scale, the crystal grain size, and the strength of the manufactured steel pipe. For comparison, Table 1 (B) shows the results in the case where no inert gas was supplied and the results in the case where the steel pipe manufactured without performing the in-line heat treatment was subjected to batch heat treatment in the bright annealing furnace after cutting. The results when batch heat treatment of the indicated ferritic stainless steel tube with less than 25% Cr is also shown.
【００２４】[0024]
【表１】 [Table 1]
【００２５】[0025]
【表２】 [Table 2]
【００２６】Ｃｒ２５％未満含有のフェライト系ステン
レス鋼管は、バッチ熱処理をしても結晶粒の粗大化は生
じない。Ｃｒ２５％以上含有のフェライト系ステンレス
鋼管は、バッチ熱処理では結晶粒の粗大化による延性低
下を生じる。しかし、本発明法によれば、Ｃｒ２５％以
上含有のフェライト系ステンレス鋼管の結晶粒粗大化に
よる延性低下が防止され、しかも内面スケールが生成さ
れない。A ferritic stainless steel tube containing less than 25% of Cr does not cause coarsening of crystal grains even when subjected to batch heat treatment. Ferritic stainless steel tubes containing 25% or more of Cr cause a decrease in ductility due to coarsening of crystal grains in batch heat treatment. However, according to the method of the present invention, a decrease in ductility due to coarsening of crystal grains of a ferritic stainless steel pipe containing 25% or more of Cr is prevented, and further, no inner surface scale is generated.
【００２７】[0027]
【発明の効果】以上の説明から明らかなように、本発明
の高耐食性フェライト系ステンレス鋼管の製造方法は、
高周波誘導加熱を利用したオンライン急速局部加熱およ
びその加熱に続く急冷により、Ｃｒ２５％以上含有鋼特
有の結晶粒粗大化による延性低下を防ぎ、製品の品質を
高める。また、ラインを進行する溶接鋼管をガスダクト
として利用して流通させる不活性ガスにより加熱部内面
をガスシールドし、内面スケールの生成をなくすことに
より、手間のかかる内面スケール除去工程を省略できる
ので、製管効率の大幅改善を達成する。これに加えて、
気密性パッキンと通気性パッキンを組み合わせ、そのパ
ッキン間に不活性ガスを供給するようにしたので、溶接
部を効果的に内面シールドすることができ、且つ、通気
性パッキンによって溶接鋼管が内面側から保持されてそ
の振れが抑えられるため、溶接品質の向上及びオンライ
ン急速局部加熱の安定化を図ることができる。そして、
溶接部近傍を含む溶接鋼管内面が広範囲に、しかも効果
的にガスシールドされるにもかかわらず、そのガス使用
量を大幅に節減することができる。 As is apparent from the above description, the method for producing a high corrosion resistant ferritic stainless steel pipe of the present invention is as follows.
The on-line rapid local heating using high-frequency induction heating and the rapid cooling subsequent to the heating prevent a decrease in ductility due to coarsening of crystal grains peculiar to steel containing 25% or more of Cr and improve the quality of products. In addition, gas shielded heating portion inner surface by the inert gas flowing by utilizing the welded steel pipe travels the line as gas duct, in particular eliminating the generation of the inner surface scale
More, Ru can omit the inner surface scale removal process time-consuming
Therefore , a significant improvement in pipe production efficiency is achieved. In addition to this,
Combine airtight packing and breathable packing, and
Since an inert gas is supplied between the packings, welding
Part can be effectively shielded on the inside and ventilated
The welded steel pipe is held from the inside by
Run-out is suppressed, improving welding quality and
Rapid stabilization of local heating can be achieved. And
The inner surface of the welded steel pipe including the vicinity of the weld is wide and effective
Use of gas despite being gas shielded
The amount can be greatly reduced.
【図１】本発明法の実施に適した連続溶接製管ラインの
概略構成図である。FIG. 1 is a schematic configuration diagram of a continuous welding pipe production line suitable for carrying out the method of the present invention.
【符号の説明】 １ 鋼板 ６ 不活性ガス供給管 ８ ノズル孔 ９ 気密性パッキン １０ 溶接鋼管 １１ 通気性パッキン １２ 高周波誘導加熱コイル １３ 散水ヘッダー[Description of Signs] 1 Steel plate 6 Inert gas supply pipe 8 Nozzle hole 9 Airtight packing 10 Welded steel pipe 11 Breathable packing 12 High frequency induction heating coil 13 Watering header
───────────────────────────────────────────────────── フロントページの続き (72)発明者 宇野 健司 茨城県猿島郡総和町大字丘里３番２ 住 金ステンレス鋼管株式会社古河工場内 (56)参考文献 特開 昭50−145357（ＪＰ，Ａ) 特開 昭50−145355（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) C21D 9/00 - 9/50 B23K 9/035 B23K 31/00──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Uno 3-2, Oazari, Oaza, Sowa-cho, Sarushima-gun, Ibaraki Pref. Sumikin Stainless Steel Pipe Co., Ltd. (56) References JP 50-145357 (JP, A JP-A-50-145355 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) C21D 9/00-9/50 B23K 9/035 B23K 31/00
Claims (1)
ト系ステンレス鋼管をオンラインで連続溶接製管する高
耐食性フェライト系ステンレス溶接鋼管の製造方法にお
いて、 成形途中の管内から溶接後の管内にかけて挿入された不
活性ガス供給管に、気密性パッキン及び通気性パッキン
を、気密性パッキンが溶接位置より上流側において管状
成形を実質的に終了した成形管の内面に密着し、通気性
パッキンが溶接位置より下流側において溶接管を内面側
から保持するように取り付けると共に、不活性ガス供給
管の先端部を閉塞して、パッキン間に位置する部分にノ
ズル孔を設け、 溶接製管中にノズル孔から不活性ガスを排出することに
より、管内のパッキン間に不活性ガスを充満させると共
に、その不活性ガスを下流側の通気性パッキンを通して
下流側へ流動させることにより、溶接部近傍及び溶接部
近傍以降の管内に不活性ガスを供給充満させ、 この状態で、前記溶接部より下流側のライン中で、内部
に不活性ガスが充満された溶接管を高周波誘導加熱手段
により管全周にわたって１０００〜１１００℃に１００
℃／秒以上の昇温速度で急速局部加熱し、均熱後その加
熱部を急冷することを特徴とする高耐食性フェライト系
ステンレス溶接鋼管の製造方法。1. A method for producing a highly corrosion-resistant ferritic stainless steel welded pipe in which a ferritic stainless steel pipe containing 25% by weight or more of Cr is continuously welded and formed on-line. the inert gas supply pipe, Oite tubular airtight packing and breathability packing, air-tightness packing upstream of the welding position
Molded in close contact with the inner surface of the substantially finished forming tube and the inner surface side Oite welded pipe downstream breathable packing than welding position
In addition to mounting so as to hold from, the tip of the inert gas supply pipe is closed, a nozzle hole is provided in the portion located between the packings, and the inert gas is discharged from the nozzle hole during welding pipe making, An inert gas is filled between the packings in the pipe, and the inert gas is caused to flow to the downstream side through the gas permeable packing on the downstream side, thereby supplying and filling the pipe near the welded portion and the pipe after the welded portion. In this state, in a line downstream of the welded portion, the welded pipe filled with an inert gas is heated to 1000 to 1100 ° C. over the entire circumference of the pipe by high-frequency induction heating means.
A method for producing a highly corrosion-resistant ferritic stainless steel welded pipe, characterized by rapidly heating locally at a rate of temperature rise of not less than ° C./sec and then rapidly cooling the heated part after soaking.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4106134A JP2787521B2 (en) | 1992-03-30 | 1992-03-30 | Method of manufacturing ferritic stainless steel welded steel pipe with high corrosion resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4106134A JP2787521B2 (en) | 1992-03-30 | 1992-03-30 | Method of manufacturing ferritic stainless steel welded steel pipe with high corrosion resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0673455A JPH0673455A (en) | 1994-03-15 |
| JP2787521B2 true JP2787521B2 (en) | 1998-08-20 |
Family
ID=14425926
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4106134A Expired - Lifetime JP2787521B2 (en) | 1992-03-30 | 1992-03-30 | Method of manufacturing ferritic stainless steel welded steel pipe with high corrosion resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2787521B2 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS50145355A (en) * | 1974-05-14 | 1975-11-21 | ||
| JPS50145357A (en) * | 1974-05-14 | 1975-11-21 |
-
1992
- 1992-03-30 JP JP4106134A patent/JP2787521B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0673455A (en) | 1994-03-15 |
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