JPS58224155A - Seamless two-phase stainless steel pipe and its manufacture - Google Patents
Seamless two-phase stainless steel pipe and its manufactureInfo
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- JPS58224155A JPS58224155A JP10586882A JP10586882A JPS58224155A JP S58224155 A JPS58224155 A JP S58224155A JP 10586882 A JP10586882 A JP 10586882A JP 10586882 A JP10586882 A JP 10586882A JP S58224155 A JPS58224155 A JP S58224155A
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Abstract
Description
【発明の詳細な説明】
本発明は2相ステンレス継目無鋼管およびその製造方法
に係り、特に生産性1歩留りが高くコストの低い2相ス
テンレス継目無鋼管の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-phase seamless stainless steel pipe and a method for manufacturing the same, and more particularly to a method for manufacturing a two-phase seamless stainless steel pipe with high productivity and low cost.
JIS 5US329J1で代表される2相ステンレス
鋼は耐食性、耐応力腐食割れ性、針溝食性にすぐれ、か
つ溶接性が良好であるため、各種化学プラント用の配管
、油井、管、地熱井管、ラインパイプ等の材料として注
目されている。Duplex stainless steel represented by JIS 5US329J1 has excellent corrosion resistance, stress corrosion cracking resistance, needle groove corrosion resistance, and good weldability, so it is used for various chemical plant piping, oil wells, pipes, geothermal well pipes, and lines. It is attracting attention as a material for pipes, etc.
ステンレス鋼の継目無鋼管は一般的にプラグミル方式、
マンドレル方式、ピルガ−ミル方式、ニージン・セジュ
ルネ方式、エアハルトブツシュペンチ方式等で製造され
ている。Seamless stainless steel pipes are generally made using the plug mill method.
It is manufactured using the mandrel method, the pilger mill method, the Nising-Sejourne method, the Erhardt-Butz-pench method, etc.
2相ステンレス鋼はフェライト−オーステナイトの2相
組職を呈しているため、熱間加工性は劣悪であるので、
熱間加工性の悪いこれらの鋼種の継目無鋼管を製造する
には、ニージン・セジュルネ法等の熱間押出法が利用さ
れていた。Since duplex stainless steel has a ferrite-austenite two-phase structure, its hot workability is poor.
In order to manufacture seamless steel pipes of these steel types that have poor hot workability, hot extrusion methods such as the Nigin-Sejourne method have been used.
しかしながら熱間押出法による直接穿孔法は。However, the direct drilling method using hot extrusion method.
穿孔に際しビレットの長さが径の5〜7倍になると偏肉
が大きく々るため、長尺管を製造するのが困難であり、
この問題全解決するため、あらかじめ機械加工によりビ
レット中央に孔をあけそれ會押拡げるいわゆるエキスパ
ンション法を用い長尺管を製造している。しかしこの方
法においてもビレットの長さは径の約15倍に限定され
ている。When drilling holes, if the length of the billet becomes 5 to 7 times the diameter, the uneven thickness will be large, making it difficult to manufacture long pipes.
In order to completely solve this problem, long tubes are manufactured using the so-called expansion method, in which a hole is made in advance in the center of the billet by machining and then expanded by pressing. However, even in this method, the length of the billet is limited to about 15 times the diameter.
また、ニージン・セジュルネ方式は、ガラス潤滑材を使
用するため圧延後、ガラス潤滑材を剥離する工程があり
、この工程は容易ではない。Furthermore, since the Nijing-Sejourne method uses a glass lubricant, there is a step of peeling off the glass lubricant after rolling, which is not easy.
本発明の目的は上記従来技術の問題点を解決し、長尺で
生産性の高い2相ステンレス継目無鋼管およびその製造
方法を提供するにある。An object of the present invention is to solve the problems of the prior art described above and to provide a long seamless duplex stainless steel pipe with high productivity and a method for manufacturing the same.
本発明の上記の目的は次の3発明によって達成される。The above objects of the present invention are achieved by the following three inventions.
第1発明の要旨とするところは次のとおりである。すな
わち1重量比にて、c:o、o3%以下。The gist of the first invention is as follows. That is, in a weight ratio of 1, c:o, o is 3% or less.
5l12.00%以下、 Mn + 2゜00%以下、
Cr:20.0〜30.0%、 Ni + 1.0〜9
.0%、Cu!4 3.0%以下、 Mo Io、5
〜5.0%、N10.05〜0.30%、At!0.0
1〜0.10%、SIo、004%以下、PIo、03
0%以下、を含有し、さらに希土類元素:(4〜20)
×〔%S〕、Cut(1〜10)X[%S〕、B:01
0005〜0.010%のうちから選ばれた1種または
2種以上を含み残部がFe および不可避的不純物よ
り成ることを特徴とするプラグミル方式よシ製造され九
2相ステンレス継目無鋼管である。5l12.00% or less, Mn+2゜00% or less,
Cr:20.0~30.0%, Ni+1.0~9
.. 0%, Cu! 4 3.0% or less, Mo Io, 5
~5.0%, N10.05~0.30%, At! 0.0
1 to 0.10%, SIo, 004% or less, PIo, 03
Contains 0% or less, and further contains rare earth elements: (4 to 20)
×[%S], Cut (1-10)X[%S], B:01
This is a 92-phase seamless stainless steel pipe manufactured by a plug mill method characterized by containing one or more selected from 0.0005 to 0.010%, with the remainder consisting of Fe and unavoidable impurities.
第2発明の要旨とするところは次のとおりである。すな
わち、第1発明と同一成分の2相ステンレス鋼の ピア
シングミルによる穿孔工程と、傾斜圧延機による傾斜圧
延工程と、プラグミルによる圧延工程と、リーラ−によ
る磨管工程と、サイザーによる外径減少工程と、を有し
て成るプラグミル方式による2相ステンレス継目無鋼管
の製造方法において、前記穿孔工程におけるビレット中
央部の温度f、1200〜1350℃、ビレット外表部
の温度11100〜1350℃で穿孔し、前記傾斜圧延
工程において1100℃以上の温度で圧延を終了し、前
記プラグミル圧延工程、磨管工程および外径縮少工程に
おいて下記(1)式で示される相当ひずみをそれぞれ0
.5 、0.4 、0.2以下で加工し、かつ前記プラ
グミル圧延工程と磨管工程ひいて下記C)式で示される
合計の相当ひずみ全0.6以下で加工することを特徴と
する2相ステンレス継目鋼鋼管の製造方法である。The gist of the second invention is as follows. That is, a piercing process using a piercing mill, an inclined rolling process using an inclined rolling mill, a rolling process using a plug mill, a tube polishing process using a reeler, and an outer diameter reducing process using a sizer for duplex stainless steel having the same composition as the first invention. In the method for manufacturing a two-phase seamless stainless steel pipe using a plug mill method, the hole is punched at a temperature f at the center of the billet in the punching step of 1200 to 1350°C, and a temperature of 11100 to 1350°C at the outer surface of the billet, In the inclined rolling process, rolling is completed at a temperature of 1100°C or higher, and in the plug mill rolling process, tube polishing process, and outer diameter reduction process, the equivalent strain expressed by the following formula (1) is reduced to 0.
.. 5, 0.4, 0.2 or less, and the plug mill rolling process, the tube polishing process, and the total equivalent strain expressed by the following C) formula are 0.6 or less. This is a method for manufacturing stainless steel jointed steel pipes.
ft−タL t(= t” ’/’。ft-ta L t (= t"'/'.
ε = tn p/b。ε = tn p/b.
tol Do ’各工程における圧延前の平均板厚。tol Do ’Average plate thickness before rolling in each process.
平均外径
t、p!各工程における圧延後の平均板厚、平均外径
ただし ε’t =tn’ p/lpo+ Zn t
R/l、。Average outer diameter t, p! Average sheet thickness and average outer diameter after rolling in each process, however, ε't = tn' p/lpo+ Zn t
R/l.
t’、 = An D、A)、。+ tn I)II/
I)II。t', = An D, A),. + tn I) II/
I) II.
11+プラグミルにおける圧延後、圧延前P、 PQ
の平均板厚
titリーラ−における圧延後、圧延前の罠、 鼠0
平均板厚
D D =プラグミルにおける圧延後、°圧延前P、
P。11+ Average plate thickness after rolling in plug mill, P before rolling, PQ after rolling in tit reeler, trap before rolling, mouse 0 Average plate thickness D D = After rolling in plug mill, ° Before rolling P,
P.
の平均外径
D D :リーラにおける圧延後、圧延前の平t、
R6
均外径
第3発明の要旨とするところは次のとおりである。すな
わち、第1発明と同一成分の2相ステンレス鋼のプラグ
ミル方式による2相ステンレス継目無鋼管の製造方法に
おいて、穿孔工程におけるビレット中央部の温度112
00〜1350℃。Average outer diameter D D : Flat t after rolling in the reeler and before rolling,
R6 Average outer diameter The gist of the third invention is as follows. That is, in the method for manufacturing a seamless two-phase stainless steel pipe using a plug mill method using two-phase stainless steel having the same components as in the first invention, the temperature at the center of the billet in the drilling step is 112
00-1350℃.
ビレット外表面部の温度t1100〜1350℃で穿孔
し、傾斜圧延工程において1100℃以上の温度で圧延
を終了し、プラグミル圧延工程および磨管工程において
前記(1)式で示される相当ひずみをそれぞれ0.5,
0.4以下で加工し、前記磨管工程後850〜1200
℃の温度で10分間以下の再加熱を施し、前記再加熱後
外径縮少工程において前記(1)式で示される相当ひず
みto、4以下で加工することを特徴とすメ2相ステン
レス継目鋼管の製造方法である。The holes are perforated at the billet outer surface temperature t of 1100 to 1350°C, the rolling is finished at a temperature of 1100°C or higher in the inclined rolling process, and the equivalent strain expressed by the above formula (1) is reduced to 0 in the plug mill rolling process and the polishing process. .5,
Processed at 0.4 or less, 850 to 1200 after the polishing process
A two-phase stainless steel joint characterized in that it is reheated at a temperature of °C for 10 minutes or less, and after said reheating, in the outer diameter reduction step, it is processed at an equivalent strain to of 4 or less as expressed by the above formula (1). This is a method for manufacturing steel pipes.
本発明者らは種々の利点を有するプラグミル方式により
2相ステンレス継目無鋼管を製造すべく化学組成、圧延
条件の検討を行い、適切な化学組成と圧延条件の組合わ
せによシ表面欠陥お上び管端割れのない2相ステンレス
継目鋼管のプラグミル方式による製造が可能であること
を見いだしたのである。The present inventors investigated the chemical composition and rolling conditions in order to manufacture duplex seamless stainless steel pipes using the plug mill method, which has various advantages. They discovered that it is possible to manufacture two-phase stainless steel jointed steel pipes without cracking or pipe end cracks using the plug mill method.
プラグミル方式とは、ピアシングミル(穿孔機。The plug mill method is a piercing mill.
第1ピアサ−とも称される)−傾斜圧延機(エロンゲー
タ−1第2ピアサ−とも称される)−プラグミル−リー
ラ−(磨管機とも称される)−サイザーの各工程で製造
する方法であるが、ニージン・セジュルネ方式より生産
性、歩留りは高く、コストは安い。(also referred to as the first piercer) - Incline rolling mill (also referred to as the elongator 1 second piercer) - Plug mill - Reeler (also referred to as the polishing machine) - A method of manufacturing in each process of the sizer. However, the productivity and yield are higher than the Nijin-Sejourne method, and the cost is lower.
次に本発明の2相ステンレス鋼の化学組成を限定した理
由について説明する。Next, the reason for limiting the chemical composition of the duplex stainless steel of the present invention will be explained.
C: Cは不可避的に鋼中に含まれる元素であるが。C: C is an element that is inevitably included in steel.
0.03%を越えると耐食性、耐粒界腐食性を劣化させ
るので0.03%以下に限定した。If it exceeds 0.03%, corrosion resistance and intergranular corrosion resistance will deteriorate, so it is limited to 0.03% or less.
Sし
St は溶解時に脱酸剤として使用される元素である
が、2.0%を越えるとσ相が発生し、冷間加工性を著
しく劣化させるので2.0%以下に限定した。S is an element used as a deoxidizing agent during melting, but if it exceeds 2.0%, σ phase will occur and cold workability will be significantly deteriorated, so it was limited to 2.0% or less.
Mn:
Mn は強度を高めるために添加されるが、2.0%を
越えると熱間加工性全劣化させるので2.0%以下に限
定した。Mn: Mn is added to increase strength, but if it exceeds 2.0%, hot workability will be completely degraded, so it is limited to 2.0% or less.
Cr +
Cr は耐食性を増加させ、またオーステナイトおよび
フェライトの2相組織を形成するため不可欠の元素であ
り、孔食や隙間腐食に対する抵抗性全考慮すると20.
0%未満ではその効果が少なく。Cr + Cr is an essential element for increasing corrosion resistance and forming a two-phase structure of austenite and ferrite, and has a resistance to pitting corrosion and crevice corrosion of 20.
If it is less than 0%, the effect is small.
一方Cr が増加するにしたがい耐孔食性は向上するが
、30.0%を越えるとσ相が析出し易くなシ靭性が劣
化するので、Crの範囲を20.0〜30.0’%に限
定しfcO
Nし
Ni は全面腐食に対する抵抗性の増加と2相組織形
成の面から不可欠な元素であるが、1.0%未満では十
分な耐食性が得られず、また9、0%を越すとその改善
効果が飽和し高価でもあるので1.0〜9.()%の範
囲に限定した。On the other hand, as the Cr content increases, the pitting corrosion resistance improves, but if it exceeds 30.0%, the σ phase tends to precipitate and the toughness deteriorates, so the range of Cr is set to 20.0 to 30.0%. Ni is an essential element in terms of increasing resistance to general corrosion and forming a two-phase structure, but if it is less than 1.0%, sufficient corrosion resistance cannot be obtained, and if it exceeds 9.0%. Since the improvement effect is saturated and it is expensive, it is 1.0 to 9. ()% range.
Cu: Cu は非酸化性酸に対する耐食性を改善するが。Cu: Although Cu improves corrosion resistance to non-oxidizing acids.
3.0%を越えると熱間加工性を劣化させるので3.0
%以下に限定した。If it exceeds 3.0%, hot workability deteriorates, so 3.0%
% or less.
MO!
Mo Ire、塩素イオンを含む腐食環境で生ずる局部
腐食に対する抵抗性を向上させる元素であるが。MO! Mo Ire is an element that improves resistance to localized corrosion that occurs in corrosive environments containing chlorine ions.
0.5%未満では十分な4食性が得られず、一方5.0
%を越えて添加しても改善効果の増加は小さく、かつ非
常に高価でもあるので、0.5〜5.0%の範囲に限定
した。If it is less than 0.5%, sufficient tetraphagy cannot be obtained;
Even if it is added in excess of 0.5%, the improvement effect is small and it is also very expensive, so it is limited to a range of 0.5 to 5.0%.
N+
N1d2相組織を形成するために重要な元素であり、ま
た耐食性を向上させるが、0.05%未満では耐孔食性
を改善せず、一方0.30%を越えると熱間加工性を著
しく劣化させるので、0.05〜0.30%の範囲に限
定し7た。N+ is an important element for forming the N1d2 phase structure and improves corrosion resistance, but if it is less than 0.05%, it will not improve pitting corrosion resistance, while if it exceeds 0.30%, it will significantly impair hot workability. Since it causes deterioration, it is limited to a range of 0.05 to 0.30%.
t j
Atd本発明に係る鋼種の熱間加工性を劣化させる酸素
を減少させる効果を有するが%0.01%未満では熱間
加工性を改善するために鋼中の酸素を減少させることが
できず、一方0.10%を越すとアルミナクラスターに
よる表面欠陥を増加させるので、0.01〜0.10%
の範囲に限定した。t j AtdIt has the effect of reducing oxygen that deteriorates the hot workability of the steel type according to the present invention, but if it is less than 0.01%, the oxygen in the steel cannot be reduced to improve the hot workability. On the other hand, if it exceeds 0.10%, surface defects due to alumina clusters will increase, so 0.01 to 0.10%
limited to the range of
S :
Sは不可避的不純物として鋼中に含有され1本発明に係
る鋼種の熱間加工性を劣化させる。その悪影響はプラグ
ミル方式における造管時に特に顕著であり、その含有量
が0.004%を越えると。S: S is contained in steel as an unavoidable impurity and deteriorates the hot workability of the steel type according to the present invention. Its adverse effects are particularly noticeable during pipe making using the plug mill method, and its content exceeds 0.004%.
硫化物の固定に有効な希土類元素(以下REMと称する
)、Ca h4に添加しても疵の発生しない造管は困
雉なので0.004%以下に限定した。Since it is difficult to make pipes without causing defects even when adding Ca, a rare earth element (hereinafter referred to as REM) that is effective in fixing sulfides, it was limited to 0.004% or less.
P :
Pも不可避的不純物として含有されるが、 0.030
%に越えると熱間加工性を劣化させ、プラグミル方式に
よる疵なしの造管は困難と彦るので0.030%以下に
限定した。P: P is also contained as an unavoidable impurity, but 0.030
If it exceeds 0.030%, the hot workability deteriorates and it becomes difficult to manufacture pipes without defects using the plug mill method, so the content was limited to 0.030% or less.
上記ノc、 si %Mn 、 Cr、 Ni 、
Cu、 Mo、 N。The above c, si%Mn, Cr, Ni,
Cu, Mo, N.
At、 S、 Pの各限定量をもって本発明の2相ス
テンレス鋼の基本成分とするが、さらにREM%Ca。The basic components of the duplex stainless steel of the present invention include limited amounts of At, S, and P, and REM% Ca.
Bを下記限定量の範囲において、1種または2種以上を
同時に含有して熱間加工性の改善を図る必要がある。こ
れらの限定理由は次の如くである。In order to improve hot workability, it is necessary to contain one type or two or more types of B at the same time within the following limited amount range. The reasons for these limitations are as follows.
REV、Cat
REVおよびCaは共に強力な硫化物形成元素であり、
硫化物を形成することにより、鋼中の固溶S量を減少さ
せ熱間加工性を改善するのに有効な元素であるがREM
<4X (%S)、Ca((%S〕の時はその効果が少
なく、一方、REM>20X〔%s)、Ca>xox(
%S〕の時はその効果が飽和し、逆にそれらの酸化物ま
たは硫化物による表面欠陥増加のおそれがあるのでRE
M:(4〜20)×〔%S〕、 Cat (i 〜1
0)x[%S]の範囲に限定した。REV, Cat REV and Ca are both strong sulfide-forming elements;
REM is an effective element for reducing the amount of solid solution S in steel and improving hot workability by forming sulfides.
<4X (%S), Ca((%S), the effect is small, while REM>20X[%s), Ca>xox(
%S], the effect is saturated and there is a risk of an increase in surface defects due to these oxides or sulfides, so RE
M: (4 ~ 20) × [%S], Cat (i ~ 1
0) x [%S].
4 B:
Bはその微量添加により熱間加工性を改善するが、0.
0005%未満ではその効果がな(,0,010%を越
える添加は逆に熱間加工性を劣化させるので、0.00
05−0.010%の範囲に限定した。4 B: B improves hot workability by adding a small amount of B, but 0.
If it is less than 0.005%, it has no effect (addition of more than 0.010% will conversely deteriorate hot workability, so
It was limited to a range of 0.05% to 0.010%.
次ニ上記成分を有する2相ステンレス鋼のプラグミル方
式による造管条件の限定理由について説明する。Next, the reasons for limiting the conditions for making a pipe using the plug mill method for duplex stainless steel having the above-mentioned components will be explained.
まず穿孔工程におけるビレット中央部の温度を限定した
のは、中央部はマンネスマン効果により本発明の限定成
分においても疵が発生し易く。First, the temperature at the center of the billet in the perforation step was limited because flaws are likely to occur in the center due to the Mannesmann effect even in the limited components of the present invention.
1200℃以上の温度を必要とするが、1350℃を越
しても疵が発生するので1200〜1350℃の温度に
限定した。次に外表面部は中央部はど苛酷表加工を受け
々いが、1100’C未満では疵が発生し、1350℃
を越しても疵が発生するので1100〜1350℃の範
囲九限定した。Although a temperature of 1,200°C or higher is required, since flaws will occur even if the temperature exceeds 1,350°C, the temperature is limited to 1,200 to 1,350°C. Next, the central part of the outer surface is subject to severe surface treatment, but flaws occur at temperatures below 1100'C;
Since scratches will occur even if the temperature exceeds 1,100 to 1,350°C, the temperature is limited to nine.
次に傾斜圧延工程において1100℃以上で圧延を終了
する理由について説明する。研究に着手した当初に10
00Cで傾斜圧延した場合忙割れが発生し% 1080
℃で傾斜圧延した場合に割れが発生しなかったが、次工
程のプラグミル圧延時に圧下率が小さいにもかかわらず
割れが発生した。Next, the reason why rolling is finished at 1100° C. or higher in the inclined rolling step will be explained. 10 at the beginning of research
When inclined rolling is performed at 00C, busy cracks occur and the percentage decreases to 1080%.
No cracks occurred when inclined rolling was carried out at °C, but cracks occurred during plug mill rolling in the next step, despite the small rolling reduction.
この事実から傾斜圧延時の加工ひずみがプラグミルにお
ける圧延に大きく影響していると考えられ。From this fact, it is thought that the processing strain during inclined rolling has a large effect on the rolling in the plug mill.
傾斜圧延後、再加熱し加工ひずみを消滅させればよいが
、省エネルギーが言われている今日、良策とは云え々い
。After tilt rolling, reheating may be used to eliminate processing strain, but this is hardly a good idea in these days when energy conservation is being talked about.
本発明者らは再加熱せず圧延する方法を見いだすべく実
験、研究を行った。すなわち、−実験室的にグリ−プル
高温高速引張試験機により、シミュレーション実験を行
った。The present inventors conducted experiments and research to find a method for rolling without reheating. That is, a simulation experiment was conducted in the laboratory using a Greeple high-temperature, high-speed tensile tester.
冷間加工においてi/′i、相当応力、相当ひずみを定
義し、単軸ひずみ硬化曲線から各種加工中の応力状態を
計算する方法が一般的に行われているが。A commonly used method is to define i/'i, equivalent stress, and equivalent strain in cold working, and calculate the stress state during various working processes from a uniaxial strain hardening curve.
熱間加工においては、再結晶が加工中に生じているので
、その加工状態を定量的に評価するため相当ひずみの概
念を適用する。In hot working, since recrystallization occurs during processing, the concept of equivalent strain is applied to quantitatively evaluate the processing state.
実験方法の詳細を以下に説明する。通常、傾斜圧延時の
(1)式で表わされる相当ひずみは約0.7である。し
たがってグリ−プル試験における予ひずみtn A/A
Q (ただしA、 !試験前の試片の断面積。The details of the experimental method will be explained below. Usually, the equivalent strain expressed by equation (1) during inclined rolling is about 0.7. Therefore, the prestrain tn A/A in the Grieple test
Q (However, A, !Cross-sectional area of the specimen before the test.
At予ひすみ後の試片の断面積)も0.7とした。The cross-sectional area of the specimen after At prestraining was also set to 0.7.
すなわち、加工スケジュールを示す第1図の工程の如く
、試片11250℃に加熱保持後、所定の温度T、まで
冷却し%t0秒間保持し、予ひずみW。That is, as in the process shown in FIG. 1 showing the processing schedule, the specimen is heated and held at 250° C., then cooled to a predetermined temperature T, held for %t0 seconds, and pre-strained W.
を与え、その後冷却して所定の温度T、に到達後17秒
間保持し、引張試験Wtを行った。was then cooled, and after reaching a predetermined temperature T, it was held for 17 seconds, and a tensile test Wt was conducted.
その結果の1例を第2図に示した。す々わち下記の第1
表に示した化学組成を有する鋼を使用し、下記第2表の
如く表示した。An example of the results is shown in FIG. The first one below
Steel having the chemical composition shown in the table was used, and the chemical composition was shown as shown in Table 2 below.
第1表
第 2 表
第2図から1050℃以下において予ひずみを与え、そ
れ以下の温度で引張るとその破断伸びtnA/A’(た
だしA/、予ひずみ後の断面積、A:破断後の断面積)
で表わされる変形能は、予ひずみを与えない場合よりも
著しく低下することが分る。1100℃以上で予ひずみ
を与え、それ以下の温度で引張っても、その破断伸びの
値は予ひずみを与え彦い場合とほぼ同程度である。すな
わち。Table 1, Table 2, Figure 2 shows that when pre-strain is applied at a temperature below 1050°C and the tension is applied at a temperature below that, the elongation at break is tnA/A' (where A/ is the cross-sectional area after pre-strain, A: after rupture). cross-sectional area)
It can be seen that the deformability expressed by is significantly lower than when no pre-strain is applied. Even if the material is pre-strained at a temperature of 1100° C. or higher and stretched at a temperature lower than that, the elongation at break is approximately the same as that obtained when the material is pre-strained. Namely.
1100℃以上での予ひすみは5次工程における加工に
影響をおよぼさ々いことが分る。1100℃未満におい
て傾斜圧延を行うと、その影響がプラグミル、リーラ−
、サイザーまで残り、ただでさえ温度が低くなり圧延が
困難なものがさらに困難になる。このため傾斜圧延の温
度1100℃以上と限定した。また、この試験結果から
、穿孔時1100℃以上で穿孔すると穿孔時の加工ひず
みは傾斜圧延時に影響をおよぼさないことが分る。It can be seen that pre-straining at a temperature of 1100° C. or higher has a significant effect on processing in the 5th step. If inclined rolling is performed at a temperature below 1100°C, the effect will be on plug mills, reelers, etc.
, the temperature remains until the sizer, and the temperature becomes low, making it even more difficult to roll. For this reason, the temperature of inclined rolling was limited to 1100°C or higher. Moreover, from this test result, it can be seen that if the temperature of the hole is 1100° C. or higher, the processing strain at the time of the hole does not affect the inclined rolling.
−次にプラグミ〜の相当ひずみ全0.5以下としたのは
、0.5fi7越えると、プラグミルで割れが発生する
か、またプラグミルで割れが発生し々〈ても次工程のリ
ーラ−において加工量を少々く圧延しても疵が発生する
。この理由からプラグミルにおける相当ひずみ’i 0
.5以下に限定した。プラグミルで割れが発生せず、リ
ーラ−で発生する場合には、プラグミルで圧延後再加熱
すればこの問題は解決されるが、加熱のためのエネルギ
ーが必要でアリ、コスト高につながる。本発明の如く相
当ひずみに0.5以下に限定すれば再加熱の必要はなく
。-Next, the reason why the total equivalent strain of Plugmi is set to be less than 0.5 is that if it exceeds 0.5fi7, cracks will occur in the plug mill, or cracks will occur in the plug mill. Even if a small amount of rolling is performed, flaws will occur. For this reason, the equivalent strain 'i 0 in the plug mill
.. It was limited to 5 or less. If cracks do not occur in the plug mill but do occur in the reeler, this problem can be solved by reheating the product after rolling in the plug mill, but this requires energy for heating, which leads to higher costs. If the equivalent strain is limited to 0.5 or less as in the present invention, there is no need for reheating.
したがって安いコストで造管できる。Therefore, pipes can be manufactured at low cost.
次にリーラ−における相当ひずみを0.4以下に限定し
た理由について説明する。需要家の要求に合致する寸法
の管を製造するためには、プラグミル工程を省略するこ
とはできない。本発明においては傾斜圧延時の温度tl
loo℃以上に限定しているが、プラグミルにおいては
それ以下の温度で圧延せざるを得ない。第2図から明ら
かなように、1100℃未満の温度での加工は次工程に
おける加工に著しい影響をおよtYす。プラグミルに
7おける加工量はリーラ−の圧延に著しい影響をお
よぼすので、プラグミルでの加工量を考慮に入れてリー
ラにおける加工量を決定しなければならない。需要家の
要求に合致した寸法の管を製造するために必要な加工量
をプラグミルで加えた場合にはリーラ−で疵が発生する
おそれがある。本発明者らは実験研究の結果、相当ひず
みio、4y越えてリーラ−で圧延すると割れが発生す
ることを見いだしたので、リーラ−における加工量を0
4以下に限定した。Next, the reason why the equivalent strain in the reeler is limited to 0.4 or less will be explained. In order to manufacture pipes with dimensions that meet customer requirements, the plug mill process cannot be omitted. In the present invention, the temperature tl during inclined rolling is
Although the rolling temperature is limited to 10° C. or higher, in a plug mill, rolling must be performed at a temperature lower than that. As is clear from FIG. 2, processing at temperatures below 1100°C has a significant effect on the processing in the next step. to plug mill
Since the amount of processing in step 7 has a significant effect on the rolling of the reeler, the amount of processing in the reeler must be determined by taking into consideration the amount of processing in the plug mill. If a plug mill is used to process the amount necessary to manufacture a pipe with dimensions that meet customer requirements, there is a risk that flaws will occur in the reeler. As a result of experimental research, the present inventors found that cracks occur when rolling with a reeler exceeds the equivalent strain io, 4y.
Limited to 4 or less.
第2発明において、プラグミル、リーラ−における合計
ひずみ’i 0.6以下とし、さらにサイザーにおける
相当ひずみを0.2以下とした理由は、プラグミルとリ
ーラ−における合計のひずみが0.6を越えると、リー
ラ−で疵が発生しなくてもサイザーの加工のとき疵が発
生する。また合計のひずみが0.6以下であっても、サ
イザーにおける相当ひずみ量が0.2を越えて圧延する
とサイザーで疵が発生する。したがってプラグミル、リ
ーラ−での合計のひずみ’t:o、6以下とし、サイザ
ーでの相当ひずみf、0.2以下に限定した。In the second invention, the total strain 'i in the plug mill and reeler is set to 0.6 or less, and the equivalent strain in the sizer is set to 0.2 or less, because if the total strain in the plug mill and reeler exceeds 0.6, Even if no flaws occur on the reeler, flaws occur when processing the sizer. Further, even if the total strain is 0.6 or less, if the equivalent strain in the sizer is rolled in excess of 0.2, flaws will occur in the sizer. Therefore, the total strain 't: o in the plug mill and reeler was set to 6 or less, and the equivalent strain f in the sizer was limited to 0.2 or less.
次に第3発明における再加熱とサイザーの加工量につい
て説明する。サイザーにおいて850℃以下で圧延する
とび相が発生し易く、サイザーにおける加工が困難とな
る。850℃以上あっても10分間を越えて加熱すると
σ相が発生し易く、サイザーにおける加工が困難に々る
。1200℃を越える高温に加熱する必要はなく、省エ
ネルギーの面からも低い温度の方が望まし、い。また再
加熱後サイザーにおいて相当ひずみが0.4ヲ越えて圧
延すると円周方向に座屈を生じる。これらの理由から磨
管工程後850・〜1200℃において10分間以下の
加熱ケ行い、サイザーにおいて相当ひずみが0.4以下
の加工をする如く限定した。Next, the amount of reheating and sizer processing in the third invention will be explained. When rolled at a temperature of 850° C. or lower in a sizer, elongation phases tend to occur, making processing in a sizer difficult. Even if the temperature is 850° C. or higher, heating for more than 10 minutes tends to generate a σ phase, making processing with a sizer difficult. There is no need to heat it to a high temperature exceeding 1200°C, and lower temperatures are preferable from the standpoint of energy conservation. Furthermore, if the material is rolled with an equivalent strain exceeding 0.4 in the sizer after reheating, buckling occurs in the circumferential direction. For these reasons, heating was carried out at 850.degree. to 1200.degree. C. for 10 minutes or less after the tube polishing step, and processing was limited so that the equivalent strain in the sizer was 0.4 or less.
実施例
第3表に示す化学成分、製造条件で造管しその結果を同
じく第3表に示した。なお本発明の条件全満足しない項
目についてはアンダーラインで示した。比較例である供
試材A1はR,EM% Ca、Bが添加されていないの
で割れが発生した。比較例A2,3,4,5,6,7は
REM、Ca、Bが本発明における下限又は上限を外れ
ているため割れが発生した。比較例A8.9,10けS
が上限を越えているため割れが発生した。比較例All
はPが上限を越えているため割れが発生した。比較例A
I 2% 13.14は穿孔時ビレットの外面中央部
の温度が本発明の下限あるいは上限を外れているため割
れが発生し念。比較例A15.16は傾斜圧延時、管温
度が本発明の下限を割っているため割れが発生した。比
較例Al 7,18,19゜20は各工程における相当
ひずみが本発明の上限を越えているため割れが発生した
。比較例A21は再加熱時の温度が下限よシ低く、比較
例A22はその時間が上限を越えているので割れが発生
した。比較例A23はザイザーにおける相当ひずみが上
限を越えているので座屈した。Example Pipe production was performed using the chemical composition and manufacturing conditions shown in Table 3, and the results are also shown in Table 3. Note that items that do not satisfy all of the conditions of the present invention are underlined. In sample material A1, which is a comparative example, cracks occurred because R, EM% Ca, and B were not added. In Comparative Examples A2, 3, 4, 5, 6, and 7, cracks occurred because REM, Ca, and B were outside the lower or upper limits of the present invention. Comparative example A8.9,10keS
Cracking occurred because the value exceeded the upper limit. Comparative examples All
Cracks occurred because P exceeded the upper limit. Comparative example A
I 2% 13.14 is due to cracking due to the temperature at the center of the outer surface of the billet being outside the lower or upper limit of the present invention during drilling. In Comparative Examples A15 and A16, cracks occurred during inclined rolling because the tube temperature was below the lower limit of the present invention. In Comparative Examples Al 7, 18, and 19°20, cracks occurred because the equivalent strain in each step exceeded the upper limit of the present invention. In Comparative Example A21, the temperature during reheating was lower than the lower limit, and in Comparative Example A22, the time exceeded the upper limit, so cracks occurred. Comparative Example A23 buckled because the equivalent strain in the Xizer exceeded the upper limit.
これに対し本発明の条件をすべて満足している本発明例
A;24〜32は各工程において割れが発生せず造管す
ることかできた。On the other hand, inventive examples A; Nos. 24 to 32, which satisfied all the conditions of the present invention, were able to be formed into pipes without cracking in each step.
本発明は上記実施例からも明らか々如く、2相ステンレ
ス鋼の成分を限定し、穿孔工程および傾斜圧延工程にお
けるビレット温度を限定し、プラグミル圧延工程、磨管
工程および外径縮少工程における相当ひずみを限定し、
必要により再加熱温度を限定することによって、すぐれ
た生産性と歩留りで2相ステンレス継目無鋼管を!ll
J造する仁とができた。As is clear from the above embodiments, the present invention limits the components of the duplex stainless steel, limits the billet temperature in the piercing process and the inclined rolling process, and makes the billet temperature suitable for the plug mill rolling process, the tube polishing process, and the outer diameter reduction process. limit strain,
By limiting the reheating temperature if necessary, we can produce two-phase seamless stainless steel pipes with excellent productivity and yield! ll
I was able to create J.
第1図は本発明におけるグリ−プル試験の試片加工スケ
ジュールを示す工程図、第2図はグリ−プル試験機を用
い、所定の温度で予ひずみを与えより低温度で引張加工
した時の引張温度と予ひすみ変形能との関係を示す線図
である。
代理人 中 路 武 雄
第1図
4 一時間(sec)
第2図
引県温戊(0C)Figure 1 is a process diagram showing the specimen processing schedule for the Greeple test in the present invention, and Figure 2 is a diagram showing the specimen processing schedule for the Greeple test in the present invention. FIG. 2 is a diagram showing the relationship between tensile temperature and pre-strain deformability. Agent Takeo Nakaji Figure 1 4 1 hour (sec) Figure 2 Prefecture Onsho (0C)
Claims (1)
.00%以下、 Mn + 2.00%以下、 Cr
: 20.0〜30.0%、Ni + 1.0〜9.0
%、Cut3.0%以下、 M。 10.5〜5.0%、 N ! 0.05〜0.30%
、At+0.01〜0.10%、s:o、oo4%以下
、P:0.030%以下、を含有し、さらに希土類元素
:(4〜20)X(%S:]、 Ca : (1〜10
)X〔%S)、B:0.0005〜0.010%のう
ちから選ばれた1種またFi2種以上を含み残部がFe
および不可避的不純物より成ることを特徴とするプラグ
ミル方式より製造された2相ステンレス継目無鋼管。 (2)重量比[てC:0.03%以下、Si:2.00
%以下、Mn + 2.00%以下、Cr : 20.
0〜30.0%、 Ni 11.0〜9.0%、Cu:
3.0%以下、 M。 二〇、5〜5.0%、N : 0.05〜0.30%
、At+0.01〜0.10%、10.004%以下、
P+0.030%以下、全含有し、さらに希土類元素:
(4〜20)×〔%S〕、Cat(1〜10)X〔%S
)、BIo、0005〜o、oio%のうちから選ばれ
た1[まf!、は281以上を含み残部がFeおよび不
可避的不純物より成る2相ステンレス鋼の ピアシング
ミルによる穿孔工程と、傾斜圧延機にiる傾斜圧延工程
と、プラグミルによる圧延工程と、リーラ−蹟よる磨管
工程と、サイザーによる外径減少工程と、を有して成る
プラグミル方式による2相ステンレス継目舖管の製造方
法において、前記穿孔工程におけるビレット中央部の温
度e1200〜1350℃、ビレット外表面部の温度を
1100〜1350℃で穿孔し、前記傾斜圧延工程にお
いて1100℃以上の温度で圧延を終了し、前記プラグ
ミル圧延工程、磨管工程および外径縮少工程において下
記(1)式で示される相当ひずみをそれぞれ0.5.0
.4.0.2以下で加工し。 かつ前記プラグミル圧延工程と磨管工程において下記(
2)式で示される合計の相当ひずみ’i 0.6以下で
加工すること?[徴とする2相ステンレス継目鋼鋼管の
製造方法。 ただし εt=Znt/16 ε、 = tn D/D。 tol DO’各工程における圧延前の平均板厚。 平均外径 t、Dj各工程における圧延後の平均板厚。 平均外径 念だし t’t=Z” ’p/’p0+ Zn tt/
l*。 tt、= tn D、/D、0 + in D
*/”*。 t、 t、01プラグミルにおける圧延後、圧延前の平
均板厚 、4 0、i、+lJ−,−えおI、、6エ。、工
。。 平均板厚 り、 D、 jプラグミルにおける圧延後、圧延前の平
均外径 DIIDl:リーラにおける圧延後、圧延前の平均O 外径 (3)重量比1c−rC:o、oa%以下、 84 :
2.00%以下、Mn:2.00%以下、Cr :
20.0〜30.0%、 Ni : 1.0〜9.0%
、Cu+3.Q%以下、 M。 :0.5〜5.0%、N:0.05〜0.30%% A
t+0.01〜0.10%、s+o、oo4%以下、P
:0.030%以下、を含有し、さらに希土類元素=(
4〜20)×〔%S:]、Ca: (1〜10)X〔%
S)、B+0.0005〜0.010%のうちから選ば
れた1種または2種以上を含み残部がFeおよび不可避
的不純物より成る2相ステンレス鋼の ピアシングミル
による穿孔工程と、傾斜圧延機による傾斜圧延工程と、
プラグミルによる圧延工程と、リーラ−による磨管工程
と、サイザーによる外径減少工程と、を有して成るプラ
グミル方式による2相ステンレス継目無鋼管の製造方法
に ゛おいて、前記穿孔工程におけるビレット中央部
の温度を1200〜1350′c、 ビレット外表面
部の温度4iioo〜1°350℃で穿孔し、前記傾斜
圧延工程において1100℃以上の温度で圧延を終了し
、前記プラグミル圧延工程および磨管工程において下記
α)式で示される相当ひずみをそれぞれ0゜5,0.4
以下で加工し、前記磨管工程後850〜1200℃の温
度で10分間以下の再加熱を施し、前記再加熱後外径縮
少工程において前記(1)式で示される相当ひずみ全0
.4以下で加工することを特徴とする2相ステンレス継
目鋼管の製造方法。 ただし t、 = An t/l。 tB =Zn D/D。 +6 + DO’各工程における圧延前の平均板厚、平
均外径 t、D?各工程における圧延後の平均板厚、平均外径[Claims] (1) Weight ratio x e: o, o 3% or less, Si: 2
.. 00% or less, Mn + 2.00% or less, Cr
: 20.0~30.0%, Ni+1.0~9.0
%, Cut 3.0% or less, M. 10.5-5.0%, N! 0.05-0.30%
, At+0.01~0.10%, s:o, oo4% or less, P:0.030% or less, and further contains rare earth elements: (4~20)X(%S:], Ca: (1 ~10
)
and unavoidable impurities. (2) Weight ratio [C: 0.03% or less, Si: 2.00
% or less, Mn + 2.00% or less, Cr: 20.
0-30.0%, Ni 11.0-9.0%, Cu:
3.0% or less, M. 20, 5-5.0%, N: 0.05-0.30%
, At+0.01 to 0.10%, 10.004% or less,
Contains P+0.030% or less, and rare earth elements:
(4-20) x [%S], Cat (1-10) x [%S
), BIo, 0005~o, oio% 1 [Maf! , is a duplex stainless steel containing 281 or more, with the remainder being Fe and unavoidable impurities.The process involves a piercing process using a piercing mill, an inclined rolling process using an inclined rolling mill, a rolling process using a plug mill, and a polishing process using a reeler. In the method for manufacturing a two-phase stainless steel joint or pipe using a plug mill method, which comprises a step of reducing the outer diameter using a sizer, a temperature e of the central part of the billet in the drilling step is 1200 to 1350°C, and a temperature of the outer surface part of the billet. is perforated at 1100 to 1350°C, the rolling is finished at a temperature of 1100°C or higher in the inclined rolling process, and the equivalent strain shown by the following formula (1) is obtained in the plug mill rolling process, tube polishing process, and outer diameter reduction process. 0.5.0 each
.. 4. Processed with 0.2 or less. And in the plug mill rolling process and polishing process, the following (
2) Is it possible to process the total equivalent strain 'i shown in the formula below 0.6? [Method for manufacturing dual-phase stainless steel jointed steel pipes. However, εt=Znt/16 ε, = tn D/D. tol DO' Average plate thickness before rolling in each process. Average outer diameter t, Dj Average plate thickness after rolling in each process. Average outer radius t't=Z"'p/'p0+ Zn tt/
l*. tt, = tn D, /D, 0 + in D
*/”*. t, t, Average plate thickness before and after rolling in the 01 plug mill, 4 0, i, +lJ-, -EoI,, 6E., Mach. Average plate thickness, D, j Average outer diameter DIIDl after rolling in the plug mill and before rolling: Average O outer diameter after rolling and before rolling in the reeler (3) Weight ratio 1c-rC: o, oa% or less, 84:
2.00% or less, Mn: 2.00% or less, Cr:
20.0-30.0%, Ni: 1.0-9.0%
, Cu+3. Q% or less, M. : 0.5-5.0%, N: 0.05-0.30%% A
t+0.01~0.10%, s+o, oo4% or less, P
: Contains 0.030% or less, and further contains rare earth elements = (
4-20)×[%S:], Ca: (1-10)×[%
S), a piercing process using a piercing mill and an inclined rolling mill for duplex stainless steel containing one or more selected from B + 0.0005 to 0.010% and the remainder consisting of Fe and unavoidable impurities. Incline rolling process;
A method for manufacturing a two-phase seamless stainless steel pipe using a plug mill method, which comprises a rolling process using a plug mill, a polishing process using a reeler, and an outer diameter reducing process using a sizer, wherein: The temperature of the billet part is 1200 to 1350'c, the temperature of the outer surface of the billet is 4iiioo to 1°350°C, the rolling is finished at a temperature of 1100°C or higher in the inclined rolling process, and the plug mill rolling process and the tube polishing process are completed. The equivalent strain shown by the following α) formula is 0°5 and 0.4, respectively.
After the polishing process, the tube is reheated at a temperature of 850 to 1200°C for 10 minutes or less, and after the reheating process, the equivalent strain expressed by the formula (1) is 0.
.. A method for producing a two-phase stainless steel jointed steel pipe, characterized in that it is processed at 4 or less. However, t, = An t/l. tB = Zn D/D. +6 + DO' Average plate thickness before rolling in each process, average outer diameter t, D? Average sheet thickness and average outside diameter after rolling in each process
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10586882A JPS58224155A (en) | 1982-06-19 | 1982-06-19 | Seamless two-phase stainless steel pipe and its manufacture |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10586882A JPS58224155A (en) | 1982-06-19 | 1982-06-19 | Seamless two-phase stainless steel pipe and its manufacture |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS58224155A true JPS58224155A (en) | 1983-12-26 |
JPS612743B2 JPS612743B2 (en) | 1986-01-27 |
Family
ID=14418929
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP10586882A Granted JPS58224155A (en) | 1982-06-19 | 1982-06-19 | Seamless two-phase stainless steel pipe and its manufacture |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS58224155A (en) |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2565999A1 (en) * | 1984-06-13 | 1985-12-20 | Nippon Kokan Kk | TWO PHASE STAINLESS STEEL HAVING IMPROVED IMPACT RESISTANCE CHARACTERISTICS |
JPS60262946A (en) * | 1984-06-11 | 1985-12-26 | Kawasaki Steel Corp | Two-phase stainless steel with superior hot workability |
JPS63157838A (en) * | 1986-12-18 | 1988-06-30 | Kawasaki Steel Corp | Two-phase stainless steel excellent in crevice corrosion resistance |
JPS63255322A (en) * | 1987-04-13 | 1988-10-21 | Kawasaki Steel Corp | Manufacture of seamless two-phase stainless steel tube |
JPH03180427A (en) * | 1989-12-08 | 1991-08-06 | Sumitomo Metal Ind Ltd | Tube making for duplex stainless steel |
EP0529943A2 (en) * | 1991-08-22 | 1993-03-03 | Kawasaki Steel Corporation | Mandrel mill for seamless steel tubes |
WO1995027090A1 (en) * | 1994-04-05 | 1995-10-12 | Sumitomo Metal Industries, Ltd. | Two-phase stainless steel |
US5513511A (en) * | 1991-08-22 | 1996-05-07 | Kawasaki Steel Corporation | Method of producing seamless steel tube by using mandrel mill |
WO1996018751A1 (en) * | 1994-12-16 | 1996-06-20 | Sumitomo Metal Industries, Ltd. | Duplex stainless steel excellent in corrosion resistance |
JP2007270265A (en) * | 2006-03-31 | 2007-10-18 | Sumitomo Metal Ind Ltd | Method for manufacturing duplex stainless steel seamless pipe |
WO2013048181A3 (en) * | 2011-09-28 | 2013-05-23 | 주식회사 포스코 | Low-alloy duplex stainless steel having outstanding corrosion resistance and hot working properties |
JP2016117944A (en) * | 2014-12-18 | 2016-06-30 | Jfeスチール株式会社 | Method of producing two-phase stainless seamless steel tube |
JP2016164288A (en) * | 2015-03-06 | 2016-09-08 | Jfeスチール株式会社 | Method for producing high strength stainless seamless steel pipe for oil well |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5446117A (en) * | 1977-09-21 | 1979-04-11 | Nippon Stainless Steel Co | Twoophase stainless steel having good hot working property |
-
1982
- 1982-06-19 JP JP10586882A patent/JPS58224155A/en active Granted
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5446117A (en) * | 1977-09-21 | 1979-04-11 | Nippon Stainless Steel Co | Twoophase stainless steel having good hot working property |
Cited By (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS60262946A (en) * | 1984-06-11 | 1985-12-26 | Kawasaki Steel Corp | Two-phase stainless steel with superior hot workability |
JPH0119465B2 (en) * | 1984-06-11 | 1989-04-11 | Kawasaki Steel Co | |
FR2565999A1 (en) * | 1984-06-13 | 1985-12-20 | Nippon Kokan Kk | TWO PHASE STAINLESS STEEL HAVING IMPROVED IMPACT RESISTANCE CHARACTERISTICS |
JPS63157838A (en) * | 1986-12-18 | 1988-06-30 | Kawasaki Steel Corp | Two-phase stainless steel excellent in crevice corrosion resistance |
JPS63255322A (en) * | 1987-04-13 | 1988-10-21 | Kawasaki Steel Corp | Manufacture of seamless two-phase stainless steel tube |
JPH03180427A (en) * | 1989-12-08 | 1991-08-06 | Sumitomo Metal Ind Ltd | Tube making for duplex stainless steel |
JPH0689398B2 (en) * | 1989-12-08 | 1994-11-09 | 住友金属工業株式会社 | Duplex Stainless Steel Pipe Making Method |
US5513511A (en) * | 1991-08-22 | 1996-05-07 | Kawasaki Steel Corporation | Method of producing seamless steel tube by using mandrel mill |
EP0529943A2 (en) * | 1991-08-22 | 1993-03-03 | Kawasaki Steel Corporation | Mandrel mill for seamless steel tubes |
WO1995027090A1 (en) * | 1994-04-05 | 1995-10-12 | Sumitomo Metal Industries, Ltd. | Two-phase stainless steel |
US5849111A (en) * | 1994-04-05 | 1998-12-15 | Sumitomo Metal Industries, Ltd. | Duplex stainless steel |
WO1996018751A1 (en) * | 1994-12-16 | 1996-06-20 | Sumitomo Metal Industries, Ltd. | Duplex stainless steel excellent in corrosion resistance |
US5672215A (en) * | 1994-12-16 | 1997-09-30 | Sumitomo Metal Industries, Ltd. | Duplex stainless steel excellent in corrosion resistance |
JP2007270265A (en) * | 2006-03-31 | 2007-10-18 | Sumitomo Metal Ind Ltd | Method for manufacturing duplex stainless steel seamless pipe |
US8613817B2 (en) | 2006-03-31 | 2013-12-24 | Nippon Steel & Sumitomo Metal Corporation | Method for producing duplex stainless steel seamless pipe |
WO2013048181A3 (en) * | 2011-09-28 | 2013-05-23 | 주식회사 포스코 | Low-alloy duplex stainless steel having outstanding corrosion resistance and hot working properties |
US10280491B2 (en) | 2011-09-28 | 2019-05-07 | Posco | Low-alloy duplex stainless steel having outstanding corrosion resistance and hot working properties |
JP2016117944A (en) * | 2014-12-18 | 2016-06-30 | Jfeスチール株式会社 | Method of producing two-phase stainless seamless steel tube |
JP2016164288A (en) * | 2015-03-06 | 2016-09-08 | Jfeスチール株式会社 | Method for producing high strength stainless seamless steel pipe for oil well |
Also Published As
Publication number | Publication date |
---|---|
JPS612743B2 (en) | 1986-01-27 |
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