JPS6159381B2 - - Google Patents
Info
- Publication number
- JPS6159381B2 JPS6159381B2 JP14709282A JP14709282A JPS6159381B2 JP S6159381 B2 JPS6159381 B2 JP S6159381B2 JP 14709282 A JP14709282 A JP 14709282A JP 14709282 A JP14709282 A JP 14709282A JP S6159381 B2 JPS6159381 B2 JP S6159381B2
- Authority
- JP
- Japan
- Prior art keywords
- pipe
- small
- diameter
- cast steel
- manufacturing
- 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
Links
- 229910001208 Crucible steel Inorganic materials 0.000 claims description 20
- 238000001816 cooling Methods 0.000 claims description 19
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 238000005482 strain hardening Methods 0.000 claims description 11
- 238000005260 corrosion Methods 0.000 claims description 10
- 230000007797 corrosion Effects 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 10
- 239000011651 chromium Substances 0.000 claims description 8
- 238000009750 centrifugal casting Methods 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 5
- 238000007711 solidification Methods 0.000 claims description 5
- 230000008023 solidification Effects 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 claims description 2
- 238000010791 quenching Methods 0.000 claims description 2
- 230000000171 quenching effect Effects 0.000 claims description 2
- 239000010959 steel Substances 0.000 claims description 2
- 238000005496 tempering Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 description 7
- 238000005266 casting Methods 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000005275 alloying Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
- C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Articles (AREA)
Description
本発明は、小口径長尺耐食鋳鋼管の製造法、詳
しくは、遠心力鋳造とその鋳造管の冷間加工との
組合せにより、クロム系鋳鋼からなる強度および
靭性にすぐれた小口径長尺耐食鋳鋼管を製造する
方法に関する。
耐食用管体は、用途・使用条件により高強度お
よび高靭性を具備することが要求される。また、
昨今用途の多様化に伴い、そのような性能を有す
る小口径長尺管が多く求められている。従来、耐
食用管材料として、Cr含有量11〜14％のいわゆ
る13Cr鋳鋼が広く使用されている。この鋳鋼
は、周知のように焼入れ焼もどし処理により高強
度が得られ、またその金属組織を、δ―フエライ
ト相２〜12％（面積率）混在した組織とすること
により、高強度と併せて高靭性を具備するものと
なる。
上記管体は遠心力鋳造法により安価にかつ容易
に製造することができる。しかし、遠心力鋳造法
は、比較的大径、短尺の管体の製造に適している
が、小口径、特に管外径100mm以下、長尺、特に
管長さ５ｍ以上の小口径長尺管の製造は実際上極
めて困難である。その対策としては遠心力鋳造管
を熱間加工に付して目的とする小口径長尺管に成
形する方法が考えられるが、δ―フエライト相を
含む混在組織の管体は著しく熱間加工性に劣るた
め、実際上解決策とはなり得ない。
本発明は、上記にかんがみてなされたものであ
り、遠心力鋳造と冷間加工とによつて、混在組織
を有する強度と靭性にすぐれた小口径長尺耐食鋳
鋼管を製造する方法を提供する。
本発明方法は、鋳鋼溶湯を遠心力鋳造に付し、
凝固後、温度600℃に到るまで、平均冷却速度を
20℃／分〜34℃／分に制御して冷却させ、得られ
た鋳造管をその後冷間加工に付して目的とする小
口径長尺管に加工することを特徴とする。
本発明において温度600℃に到るまでの平均冷
却速度を20℃／分以上とするのは、得られる鋳造
管の結晶粒を微細化することにより、その後の冷
間加工に必要な加工性を付与するためである。結
晶粒の大きさは、凝固後の冷却速度により左右さ
〓〓〓〓
れ、冷却速度を高めることにより、結晶粒の成長
が抑制され微細な組織となる。その急冷による微
細化効果は、再結晶温度（本発明の対象とする鋳
鋼では、約900℃前後）までの温度範囲において
大である。従つて、凝固後、再結晶温度に到るま
での間を、20℃／分以上で冷却すれば十分である
が、工業生産上、高温域での冷却速度の測定は困
難であるので、実操業上での温度管理の便宜を考
慮して600℃に到るまでの間を20℃／分以上で冷
却することとした。冷却速度を高める程、微細な
結晶粒となり、またその冷却によつて品質上の問
題を生じることもないが、約34℃／分までの冷却
速度で十分目的を達することができ、それ以上に
冷却速度を高める必要はなく、またそれ以上に冷
却速度を高めることは実作業上困難を増すので、
34℃／分を上限とする。上記の冷却速度の制御に
よつて後記実施例にも示されるように、小口径長
尺管への加工を、クラツク等が生じることなく円
滑に達成することが可能となる。
本発明に使用される鋳鋼は、Cr系鋳鋼、代表
的には、Cr含有量11〜14％のいわゆる13Cr鋳鋼
であつて、C0.04〜0.15％、Si0.2〜0.6％、Mn0.5
〜1.5％、Cr11〜14％、残部実質的にFeからなる
基本成分組成を有するものであり、また材質の改
善を目的として、各種合金元素、例えば、Ni0.2
〜1.0％、Mo0.2〜1.0％、N0.04〜2.0％等を含有
する鋳鋼も適宜使用される。
本発明における遠心力鋳造は常法に従つて行え
ばよく、またその鋳造サイズも、目的とする小口
径長尺管のサイズに応じて適宜決めればよい。
鋳造後、前記冷却速度の制御下に得られた鋳造
管は、常法に従い、焼入れ・焼もどし処理され、
この熱処理により所要の強度が与えられる。な
お、強度および靭性の面から、その組織における
δ―フエライト量は２〜12％（面積率）であるの
が好ましい。むろん、その量は、化学成分組成と
熱処理条件とによつて任意に調整することができ
る。
上記熱処理後、冷間加工を行い目的とする小口
径長尺管体に加工する。その冷間加工は例えばプ
レス絞り加工、その他適当な方法を用いて行えば
よく、また特別の加工条件を必要としない。な
お、冷間加工に先立つて、鋳造管の内外面を機械
加工しておくとよい。
次に、本発明の実施例として、第１表に示す化
学成分組成の13Cr鋳鋼(A)および(B)を溶製し、そ
れぞれにつき遠心力鋳造に付して、外径120mm、
肉厚28mm、長さ４ｍの鋳造管を製造した。なお、
凝固後、温度600℃に到るまでの平均冷却速度は
20℃／分〜34℃／分とする一方、比較例として冷
却速度を制御せず、通常の条件（平均冷却速度20
℃／分未満）で冷却させた鋳造管を製造した。得
られた各鋳造管を、温度980℃の焼入れ、670℃で
の焼もどし処理したのち、内外面に機械加工を加
え、ついで冷間プレス絞り加工を行つて、外径80
mm、肉厚21mm、長さ８ｍの小口径長尺管に仕上げ
た。それぞれの供試管について製造条件と冷間加
工結果を示せば第２表のとおりである。
The present invention provides a method for producing a long, corrosion-resistant, small-diameter cast steel pipe, and more specifically, a method for manufacturing a long, corrosion-resistant, small-diameter, corrosion-resistant cast steel pipe made of chromium-based cast steel, which is made of chromium-based cast steel and has excellent strength and toughness. The present invention relates to a method of manufacturing cast steel pipes. Corrosion-resistant pipes are required to have high strength and high toughness depending on the application and usage conditions. Also,
With the recent diversification of applications, there is a growing demand for small-diameter long pipes with such performance. Conventionally, so-called 13Cr cast steel with a Cr content of 11 to 14% has been widely used as a corrosion-resistant pipe material. As is well known, high strength can be obtained from this cast steel by quenching and tempering, and by making the metal structure a mixed structure of 2 to 12% (area ratio) of δ-ferrite phase, it has high strength as well. It has high toughness. The tube body can be manufactured easily and inexpensively by centrifugal casting. However, the centrifugal casting method is suitable for manufacturing relatively large diameter and short tubes, but it is suitable for manufacturing small diameter long tubes, especially those with an outer diameter of 100 mm or less and long tubes, especially those with a length of 5 m or more. Manufacturing is extremely difficult in practice. A possible countermeasure to this problem is to subject centrifugally cast tubes to hot working to form the desired small-diameter long tube, but tubes with a mixed structure containing the δ-ferrite phase are extremely difficult to hot work. This cannot be a practical solution. The present invention has been made in view of the above, and provides a method for manufacturing a small-diameter long corrosion-resistant cast steel pipe having a mixed structure and excellent strength and toughness by centrifugal force casting and cold working. . The method of the present invention involves subjecting molten cast steel to centrifugal casting,
After solidification, the average cooling rate is maintained until the temperature reaches 600℃.
It is characterized by cooling at a controlled rate of 20° C./min to 34° C./min, and then subjecting the obtained cast tube to cold working to form the desired small-diameter long tube. In the present invention, the average cooling rate is set to 20°C/min or more until the temperature reaches 600°C. By refining the crystal grains of the resulting cast tube, the workability required for subsequent cold working is improved. This is for the purpose of granting. The size of crystal grains depends on the cooling rate after solidification〓〓〓〓
By increasing the cooling rate, the growth of crystal grains is suppressed and a fine structure is formed. The refinement effect of rapid cooling is large in the temperature range up to the recrystallization temperature (approximately 900° C. in the case of cast steel, which is the object of the present invention). Therefore, it is sufficient to cool at 20°C/min or more after solidification until the recrystallization temperature is reached, but it is difficult to measure the cooling rate at high temperatures in industrial production, so this is not practical. Considering the convenience of temperature control during operation, it was decided to cool at a rate of 20°C/min or more until the temperature reached 600°C. The higher the cooling rate, the finer the crystal grains will be, and the cooling will not cause any quality problems, but a cooling rate of up to about 34°C/min is sufficient to achieve the purpose; There is no need to increase the cooling rate, and increasing the cooling rate further increases the difficulty in actual work, so
The upper limit is 34℃/min. By controlling the cooling rate as described above, it is possible to smoothly process the tube into a small-diameter long tube without causing any cracks or the like, as shown in the examples below. The cast steel used in the present invention is Cr-based cast steel, typically so-called 13Cr cast steel with a Cr content of 11 to 14%, including 0.04 to 0.15% C, 0.2 to 0.6% Si, and 0.5% Mn.
~1.5% Cr, 11~14% Cr, and the remainder substantially Fe, and for the purpose of improving the material, various alloying elements such as Ni0.2
Cast steel containing ~1.0%, Mo0.2~1.0%, N0.04~2.0%, etc. is also used as appropriate. The centrifugal casting in the present invention may be carried out according to a conventional method, and the casting size may be appropriately determined depending on the size of the intended small-diameter long tube. After casting, the cast pipe obtained under the control of the cooling rate is quenched and tempered according to a conventional method,
This heat treatment provides the required strength. From the viewpoint of strength and toughness, the amount of δ-ferrite in the structure is preferably 2 to 12% (area ratio). Of course, the amount can be arbitrarily adjusted depending on the chemical composition and heat treatment conditions. After the above-mentioned heat treatment, cold working is performed to form the desired small-diameter elongated tube. The cold working may be carried out using, for example, press drawing or other suitable methods, and no special working conditions are required. Note that it is preferable to machine the inner and outer surfaces of the cast tube prior to cold working. Next, as an example of the present invention, 13Cr cast steels (A) and (B) having the chemical compositions shown in Table 1 were melted and subjected to centrifugal force casting, so that the outer diameter was 120 mm.
A cast pipe with a wall thickness of 28 mm and a length of 4 m was manufactured. In addition,
After solidification, the average cooling rate until the temperature reaches 600℃ is
20°C/min to 34°C/min, while as a comparative example, the cooling rate was not controlled and normal conditions (average cooling rate 20°C/min) were used.
Cast tubes were produced that were cooled at less than 0.degree. C./min). Each of the resulting cast tubes was quenched at a temperature of 980°C and tempered at 670°C, then machined on the inner and outer surfaces, and then cold press drawn to have an outer diameter of 80°.
It was finished into a small diameter long tube with a wall thickness of 21 mm and a length of 8 m. Table 2 shows the manufacturing conditions and cold working results for each test tube.
【表】
〓〓〓〓
[Table] 〓〓〓〓
【表】
上記試験結果から明らかなように、通常の冷却
条件下に得られる鋳造管は、いずれも冷間加工時
に割れが発生しており、冷間加工による小口径長
尺管への加工が不可能であるのに対し、本発明方
法によれば、割れを生じることなく、目的とする
小口径長尺管が得られる。なお、本発明により得
られる鋳鋼管は、δ―フエライト相を２〜12％含
む組織とすることにより、混在組織の特徴である
高強度と高靭性とを兼備するものである。
このように、本発明は、遠心力鋳造と冷間加工
の組合せにより小口径長尺管の製造を可能とした
ものであり、これによつて外径100mm以下、長さ
５ｍ以上の小口径長尺サイズを有する強度と靭性
にすぐれた耐食用鋳鋼管を製造することができ
る。また、素管は遠心力鋳造管であるから、比較
的安価であり、かつ適用される材料面の制約も少
い。本発明により得られる鋳鋼管は、各種耐食用
パイピング材、油井用チユービング材、ケーシン
グ材、熱交換器用パイプ材など、広範な用途に好
適に使用されるものである。
〓〓〓〓
[Table] As is clear from the above test results, all cast pipes obtained under normal cooling conditions cracked during cold working, making it difficult to process them into small diameter long pipes by cold working. However, according to the method of the present invention, the desired long tube with a small diameter can be obtained without cracking. The cast steel pipe obtained by the present invention has a structure containing 2 to 12% of the δ-ferrite phase, thereby achieving both high strength and high toughness, which are characteristics of a mixed structure. As described above, the present invention makes it possible to manufacture small-diameter long tubes by combining centrifugal force casting and cold working. It is possible to produce corrosion-resistant cast steel pipes with excellent strength and toughness. Furthermore, since the raw tube is a centrifugally cast tube, it is relatively inexpensive and there are few restrictions on the material to be applied. The cast steel pipe obtained by the present invention is suitably used in a wide range of applications, such as various corrosion-resistant piping materials, oil well tubing materials, casing materials, and heat exchanger pipe materials. 〓〓〓〓
Claims (1)
の製造方法であつて、該鋳鋼溶湯を遠心力鋳造に
付し、凝固後、温度600℃に到るまでの平均冷却
速度を20℃／分〜34℃／分に制御して鋳造管を
得、焼入れ・焼きもどし後、冷間加工に付して小
口径長尺管に加工することを特徴とする小口径長
尺耐食鋳鋼管の製造法。 ２ 冷間加工により、管外径100mm以下、管長さ
５ｍ以上の管体に加工することを特徴とする上記
第１項に記載の小口径長尺耐食鋳鋼管の製造法。[Claims] 1. A method for manufacturing a small-diameter long pipe made of 11 to 14% chromium-based cast steel, which involves subjecting the molten steel to centrifugal casting and, after solidification, heating it to a temperature of 600°C. A small-diameter pipe characterized by controlling the average cooling rate to 20°C/min to 34°C/min to obtain a cast pipe, quenching and tempering, and then subjecting it to cold working to form a small-diameter long pipe. Manufacturing method for long corrosion-resistant cast steel pipes. 2. The method for manufacturing a small-diameter long corrosion-resistant cast steel pipe according to item 1 above, characterized in that the pipe is cold-worked into a pipe having an outer diameter of 100 mm or less and a pipe length of 5 m or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14709282A JPS5935621A (en) | 1982-08-24 | 1982-08-24 | Production of corrosion resistant cast steel having small bore and long size |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14709282A JPS5935621A (en) | 1982-08-24 | 1982-08-24 | Production of corrosion resistant cast steel having small bore and long size |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5935621A JPS5935621A (en) | 1984-02-27 |
| JPS6159381B2 true JPS6159381B2 (en) | 1986-12-16 |
Family
ID=15422288
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14709282A Granted JPS5935621A (en) | 1982-08-24 | 1982-08-24 | Production of corrosion resistant cast steel having small bore and long size |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5935621A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4899763A (en) * | 1988-10-07 | 1990-02-13 | Safeguard Industrial Corporation | Therapeutic appliance for the wrist |
| CN102233417B (en) * | 2011-07-07 | 2012-10-31 | 烟台台海玛努尔核电设备股份有限公司 | Centrifugal casting process for main pipeline of million kilowatt-grade nuclear power plant |
| CN103658580A (en) * | 2013-12-10 | 2014-03-26 | 江苏宏宝集团有限公司 | Alloy pipe production process |
| WO2018181314A1 (en) | 2017-03-29 | 2018-10-04 | テルモ株式会社 | Tourniquet and hemostatic method |
-
1982
- 1982-08-24 JP JP14709282A patent/JPS5935621A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5935621A (en) | 1984-02-27 |
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