JPH0218381B2 - - Google Patents
Info
- Publication number
- JPH0218381B2 JPH0218381B2 JP59251908A JP25190884A JPH0218381B2 JP H0218381 B2 JPH0218381 B2 JP H0218381B2 JP 59251908 A JP59251908 A JP 59251908A JP 25190884 A JP25190884 A JP 25190884A JP H0218381 B2 JPH0218381 B2 JP H0218381B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- strength
- drill collars
- stress corrosion
- toughness
- 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
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 41
- 239000010959 steel Substances 0.000 claims abstract description 41
- 230000007797 corrosion Effects 0.000 claims abstract description 28
- 238000005260 corrosion Methods 0.000 claims abstract description 28
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 229910052758 niobium Inorganic materials 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 239000000463 material Substances 0.000 abstract description 20
- 238000005336 cracking Methods 0.000 abstract description 13
- 239000000203 mixture Substances 0.000 abstract description 3
- 229910000851 Alloy steel Inorganic materials 0.000 abstract 3
- 230000035882 stress Effects 0.000 description 16
- 230000000694 effects Effects 0.000 description 10
- 150000001247 metal acetylides Chemical class 0.000 description 10
- 229910052719 titanium Inorganic materials 0.000 description 8
- 238000005096 rolling process Methods 0.000 description 6
- 238000005728 strengthening Methods 0.000 description 6
- 229910000765 intermetallic Inorganic materials 0.000 description 5
- 229910052720 vanadium Inorganic materials 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 4
- 230000032683 aging Effects 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 229910018487 Ni—Cr Inorganic materials 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 3
- 238000005553 drilling Methods 0.000 description 3
- 238000005242 forging Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229910052726 zirconium Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 239000003129 oil well Substances 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 229910000760 Hardened steel Inorganic materials 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical class [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000006757 chemical reactions by type Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- -1 chlorine ions Chemical class 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/16—Drill collars
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
Abstract
Description
〔産業上の利用分野〕
本発明は耐応力腐食割れ性にすぐれたドリルカ
ラー用非磁性鋼に関するものである。
〔従来の技術〕
近年、石油資源の枯渇化にともない、石油探査
はさらに深部あるいは海底油田等の厳しい環境条
件下に移行しつつある。かかる石油探査のために
高強度非磁性鋼製のドリルカラーが使用される。
このドリルカラーとはビツト（油井掘さく用のき
りに相当する部品）の直上に取り付けられビツト
に荷重を加え掘進効率を高めるための厚肉鋼管
で、その寸法の一例は外径250mm、肉厚70mm、長
さ10ｍといつたもので、しかもかなりの強度・靭
性が要求され、一般的なドリルカラー用鋼材とし
て機械的性質は耐力ほぼ60Kgｆ／mm2〜80Kgｆ／mm2
程度、伸びほぼ25％以上程度が要求されるもので
あるが、探査環境の苛酷化にともない塩素イオン
による応力腐食割れ等の問題が生じている。即
ち、深井戸になると地層中の塩化物量も増し、ま
た温度も高くなることから高温塩素イオン環境に
さらされることになり、前記の問題を考慮する必
要がある。
所で、これまで高強度非磁性鋼として高Mn鋼
及びNi―Cr鋼が、たとえばDIN規格の
X50MnCrV2014（1.3819）等により知られてい
る。これら内、まず高Mn鋼は、その耐食性がCr
を添加することにより改善されるが、Ni―Cr鋼
に比べる耐食性はかなり劣る。とくにMnは塩素
イオン環境下での耐応力腐食割れ性を劣化させる
ことから標記用途には適しない。さらに高Mn鋼
は主に炭化物による析出強化を利用しているた
め、ドリルカラー素材となる丸鋼（直径約200mm）
の溶体化処理に際しては丸鋼内部は冷却速度が遅
くなることから冷却中に炭化物が析出する。した
がつてその後の時効処理による強化が半径方向で
変化することになり、材質の均質性の点に問題が
ある。
一方高強度Ni―Crオーステナイト鋼としては
古くから析出強化型オーステナイトステンレス鋼
が知られている。例えば金属間化合物γ′：〔Ni3
（Al，Ti）〕の析出強化を利用したA286
（AISI660）がある。しかしCr量が15％程度であ
るため十分な耐食性が得られない。さらにこの鋼
はＣ量を0.05％程度含有しているため、Tiの炭化
物が生成し易く、とくにドリルカラー素材の丸鋼
（直径約200mm）サイズでは鋼塊あるいは鋳片凝固
段階で粗大なTi炭化物として存在し、これらは
その後の加熱及び圧延工程でも完全に消滅させる
ことはできない。これらの粗大Ti炭化物は破壊
の起点となり、またクラツクの伝播を助長するこ
とから、材料の延性及び靭性を損うことになる。
さらに材料特性に悪影響を及ぼす粗大Ti炭化物
の分布は丸鋼の半径方向あるいは長手方向にも変
化することから、十分に均質な素材丸鋼を得るこ
とが困難になる。
〔発明が解決しようとする問題点〕
以上のように従来の高強度非磁性鋼では耐食性
とくに耐応力腐食割れ性あるいは延性，靭性が十
分でなく、また材質の均質性の点でも不十分であ
り、ドリルカラーの寿命及び信頼性の点に問題が
あつた。
〔問題点を解決するための手段〕
以上のように従来鋼は耐食性とくに耐応力腐食
割れ性が十分でなく、また延性・靭性も不足して
おり、さらに丸鋼材質の均質性にも問題がある。
そこで本発明者らはこれらの点につき種々検討を
行なつた結果、耐応力腐食割れ性についてはCr
及びNi量を十分確保することにより解決できる
ことが明らかになつた。つぎに延性，靭性の改善
及び材質の均質化については、Ti，Cr，Mo，
Nb，Ｖ，等の炭化物あるいは窒化物形成元素と
化合物を作り易いＣとＮを極めて低く制限するこ
とにより、延性・靭性及び均質性を大巾に改善す
ることができるという新たな知見を得た。
本発明は以上のような知見に基いてなされたも
のであつてその要旨とする所は、重量％でSi≦
2.0％，Mn≦2.0％，Ni25〜40％，Cr18〜30％，
Al0.1〜1.5％，Ti1.5〜3.0％，Ca0.0005〜0.020％
を含有し、Ｃ≦0.015％，Ｎ≦0.010％に制限し、
又はこれにさらにMo≦30％あるいはZr≦0.5％，
Nb≦0.5％，Ｖ≦0.5％の１種又は２種以上を含有
し、残部がFe及び不可避不純物からなることを
特徴とする高耐食性高強度ドリルカラー用非磁性
鋼にある。
以下に本発明を詳細に説明する。
先ず本発明の成分系において、Si及びMnはい
ずれも脱酸剤として必要であるが、Siは過剰に存
在すると熱間加工性を損うこと、またMnは2.0％
を超えると耐応力腐食割れ性を劣化させることか
ら、これらの元素はいずれも2.0％以下にする。
次にNi及びCrは本発明の基本となる元素であ
る。まずNiは後述のCrと共存して非磁性の前提
となる安定オーステナイト相を確保するための主
要成分である。本発明鋼は時効処理により金属間
化合物γ′相：Ni3（Al，Ti）を析出させ高強度化
した、いわゆる析出硬化鋼であるため、Niは強
化元素としての作用を有する。さらには深井戸用
のドリルカラーで問題となる塩素イオン環境下で
の耐応力腐食割れ性を確保するため25％以上を必
要とする。しかし耐応力腐食割れ性の改善効果は
40％で飽飽和することから上限を40％とした。又
Crは耐食性を確保するため18％以上必要である。
しかし、30％を超えると熱間加工性を損い、また
オーステナイト相を不安定にすることから上限を
30％とした。
これらNi及びCrの適正範囲は次のような実験
に基いて決められた。即ち、第１図は応力腐食破
断時間に及ぼすCr量及びNi量の影響を示す図で
あつて、これらはC0.010％，Si0.5％，Mn1.2％，
Al0.5％，Ti2.0％，Ca0.0010％，N0.005％を基本
成分とし、Niを30％としてCr量を種々変化させ
たもの、及びCrを20％としてNi量を種種変化さ
せたものについて、平行部直径６mmの試験片を用
い飽和食塩水・沸騰条件下で応力80Kgｆ／mm2で定
荷重型応力腐食割れ試験を行なつた結果を示すも
のである。同図から明らかなようにCr18％以上
及びNi25％以上でいずれも応力腐食破断時間が
飛躍的に向上することが判る。なおこの効果は
Niにおいては40％ですでに飽和することが明ら
かである。一方Crについては30％を超えてもそ
の効果はなお増大するが、前述の通り熱間加工性
を損うのでCrの上限は30％と定められた。
次に、Alは本発明鋼を強化する析出物、即ち
金属間化合物γ′：Ni3（Al，Ti）を形成する元素
である。また延性及び靭性に有害な作用を有する
粒界反応型析出物であるη相の析出を抑制する効
果をもつ。しかし過剰に添加するとオーステナイ
ト相とγ′との整合歪を減少させるため析出硬化作
用を弱めることになる。したがつてAlの含有量
を0.1％から1.5％とした。また、Tiは金属間化合
物γ′：Ni3（Al，Ti）を形成する主要元素であり
Ti量とともに強度は上昇する。ドリルカラーは
地圧に耐える必要があり、そのため高強度である
ことが要件であるが、その高強度を確保するため
にはTiは最低1.5％必要である。しかし３％を超
えて添加すると著しく熱間加工性を損うことか
ら、その含有量を1.5％から３％とした。
さらにCaは熱間加工性を向上させる元素とし
て0.0005％以上を必要とするが、0.020％を超え
ると逆に熱間加工性を劣化させる。したがつて
Caの含有量を0.0005〜0.020％とした。
次に本発明においてはＣ及びＮの量を制限する
ことによつて、Ti，Cr，Mo，Nb，Zr，Ｖ等の
炭化物あるいは窒化物の発生を抑制し、これによ
つてドリルカラー用鋼材として必要な、延性・靭
性及び均質性を確保するものである。まずＣは鋼
の凝固過程でTiと化合し粗大なTi炭化物を形成
する。この粗大炭化物はその後の加熱・圧延ある
いは溶体化熱処理工程での固溶が困難である。一
方ドリルカラーは掘さく中にトルクの変化あるい
は地層の変化にともなう衝撃力を受けるので、こ
れらによる破壊を防ぐため延性・靭性及び材質の
均質性が必要となるが、前述した未固溶の粗大炭
化物は延性・靭性を損うのみならず材質を不均質
化する。このような粗大炭化物の残留を防止する
ためにはＣ量を0.015％以下に制限する要がある。
ＮはＣよりもさらにTiと結合して粗大なTi窒
化物を形成し易い元素であることから、上記のＣ
の場合と同様ドリルカラー用としての必要特性で
ある延性，靭性及び均質性を損うため制限する必
要がある。ＮはＣよりTiと化合物を形成し易い
ことからＣより低く上限を0.010％としなければ
ならない。これらＣ及びＮの適正範囲は次のよう
な効果に基いて定められたものである。即ち第２
図は機械的性質に及ぼすＣとＮの影響を示す図で
あつて、これらはSi0.5％，Mn1.2％，Cr20％，
Ni34％，Al0.5％，Ti2％，Ca0.0010％を基本成
分としＮを0.006％としＣ量を変化させたもの、
及びＣを0.010％としＮ量を変化させたものにつ
いて、夫々溶解後圧延あるいは鍛造により150φ
mmの丸鋼に成形後、溶体化処理及び時効処理を行
ない、しかるのち第２図中に記入した図に示す試
験片採取位置から、JIS4号引張試験片を採取し、
JIS Z2241により引張試験を行ない耐力及び伸び
を測定した結果を示すものである。同図から明ら
かな如く、Ｃが0.015％以下、Ｎが0.010％以下に
おいていずれも高い耐力と十分な伸びを示し、か
ついずれの採取位置もほぼ同じ耐力及び伸び値を
有し材質も均質であり、さらにこれらの機械的性
質は耐力70Kgｆ／mm2以上、及び伸び25％以上とい
ずれも充分満足なものであることが明らかであ
る。これはＣ及びＮが夫々上記の値を超えると、
前述の通りTi等との炭窒化物を形成し、延性，
靭性を損うためである。このようにして、Ｃ及び
Ｎの上限値を前述の如く制限した。
以上が本発明における基本成分系であるが、本
発明においては、さらに高強度のドリルカラー用
として耐力の向上をはかるために、Moあるいは
Zr，Nb，Ｖの１種または２種以上を所定の範囲
内で含有せしめることが有効である。
まずMoは固溶強化作用のある元素であり、耐
力を高めるために有効な元素であるが、３％以上
添加すると熱間変形抵抗を著しく高めるため圧延
あるいは鍛造が困難になる。したがつて含有量は
3.0％以下とした。
さらにZr，Nb及びＶは析出強化をもたらす金
属間化合物γ′の中に固溶するため、これら元素の
添加はγ′の析出量を増加させることになり、結果
として耐力を高めることになる。しかし過剰の添
加は延性，靭性を損うことから上限をそれぞれ
0.5％とした。
以上の如き成分組成を有する本発明鋼は、各種
電気炉等による製鋼を行なつた後、造塊・分塊圧
延あるいは連続鋳造により鋼片とした後、圧延あ
るいは鍛造により丸鋼とし、しかる後溶体化処理
及び時効処理を施しドリルカラー素材とすること
が出来る。
以下に本発明の効果を実施例に基いてさらに具
体的に示す。
〔実施例〕
第１表に本発明鋼と比較鋼の化学成分及び形状
を示す。第２表は第１表の鋼について、丸鋼表層
から20mm及び60mm下の位置での材料特性を示した
ものである。これら特性調査結果から明らかなよ
うに、本発明鋼は比較鋼に比べ耐応力腐食割れ性
及び材質の均質性においてすぐれたものである。
[Industrial Field of Application] The present invention relates to a non-magnetic steel for drill collars that has excellent stress corrosion cracking resistance. [Prior Art] In recent years, with the depletion of petroleum resources, petroleum exploration is moving deeper into the ocean or under severe environmental conditions, such as in offshore oil fields. Drill collars made of high strength non-magnetic steel are used for such oil exploration.
This drill collar is a thick-walled steel pipe that is attached directly above the bit (a part equivalent to a drill bit for oil well drilling) to add load to the bit and increase drilling efficiency.One example of its dimensions is an outer diameter of 250 mm, and a wall thickness of 250 mm. 70mm and 10m in length, it requires considerable strength and toughness, and as a general steel material for drill collars, the mechanical properties are approximately 60Kgf/mm 2 ~ 80Kgf/mm 2
However, as the exploration environment becomes more severe, problems such as stress corrosion cracking due to chlorine ions are occurring. That is, as the well becomes deeper, the amount of chloride in the stratum increases and the temperature also rises, meaning that the well is exposed to a high-temperature chlorine ion environment, and it is necessary to take the above-mentioned problems into consideration. By the way, high Mn steel and Ni-Cr steel have been used as high-strength non-magnetic steels, for example, according to DIN standards.
It is known as X50MnCrV2014 (1.3819) etc. Among these, high Mn steel has a high corrosion resistance due to Cr.
However, the corrosion resistance is considerably inferior to that of Ni-Cr steel. In particular, Mn deteriorates stress corrosion cracking resistance in a chloride ion environment, so it is not suitable for the above-mentioned applications. Furthermore, since high Mn steel mainly utilizes precipitation strengthening by carbides, round steel (approximately 200 mm in diameter) is used as the material for drill collars.
During solution treatment, the cooling rate inside the round steel is slow, so carbides precipitate during cooling. Therefore, the strengthening caused by the subsequent aging treatment changes in the radial direction, which poses a problem in terms of the homogeneity of the material. On the other hand, precipitation-strengthened austenitic stainless steel has been known for a long time as a high-strength Ni-Cr austenitic steel. For example, intermetallic compound γ′: [Ni 3
A286 using precipitation strengthening of (Al, Ti)]
(AISI660). However, since the Cr content is about 15%, sufficient corrosion resistance cannot be obtained. Furthermore, since this steel contains about 0.05% C, Ti carbides are likely to form, and especially in round steel (approximately 200 mm in diameter), which is the material for drill collars, coarse Ti carbides form during the solidification stage of the steel ingot or slab. These cannot be completely eliminated even in the subsequent heating and rolling process. These coarse Ti carbides serve as starting points for fractures and promote crack propagation, thereby impairing the ductility and toughness of the material.
Furthermore, the distribution of coarse Ti carbides that adversely affect material properties also changes in the radial or longitudinal direction of the round steel, making it difficult to obtain a sufficiently homogeneous round steel material. [Problems to be solved by the invention] As described above, conventional high-strength nonmagnetic steels do not have sufficient corrosion resistance, especially stress corrosion cracking resistance, ductility, and toughness, and are also insufficient in terms of material homogeneity. However, there were problems with the lifespan and reliability of the drill collar. [Means for solving the problems] As mentioned above, conventional steels do not have sufficient corrosion resistance, especially stress corrosion cracking resistance, and also lack ductility and toughness.Furthermore, there are problems with the homogeneity of the round steel material. be.
Therefore, the present inventors conducted various studies on these points, and as a result, the stress corrosion cracking resistance of Cr
It has become clear that this problem can be solved by ensuring a sufficient amount of Ni. Next, regarding improvement of ductility and toughness and homogenization of material, Ti, Cr, Mo,
We obtained new knowledge that ductility, toughness, and homogeneity can be greatly improved by limiting C and N, which easily form compounds with carbide- or nitride-forming elements such as Nb and V, to extremely low levels. . The present invention was made based on the above knowledge, and its gist is that Si ≦
2.0%, Mn≦2.0%, Ni25~40%, Cr18~30%,
Al0.1~1.5%, Ti1.5~3.0%, Ca0.0005~0.020%
Contains, limited to C≦0.015%, N≦0.010%,
Or in addition to this, Mo≦30% or Zr≦0.5%,
A highly corrosion-resistant, high-strength non-magnetic steel for drill collars containing one or more of Nb≦0.5% and V≦0.5%, with the remainder consisting of Fe and inevitable impurities. The present invention will be explained in detail below. First, in the component system of the present invention, both Si and Mn are necessary as deoxidizing agents, but excessive presence of Si impairs hot workability, and Mn is 2.0%.
If the content of these elements exceeds 2.0%, stress corrosion cracking resistance deteriorates, so the content of each of these elements should be 2.0% or less. Next, Ni and Cr are the basic elements of the present invention. First, Ni is a main component that coexists with Cr, which will be described later, to ensure a stable austenite phase, which is a prerequisite for nonmagnetism. The steel of the present invention is a so-called precipitation-hardened steel in which the intermetallic compound γ' phase: Ni 3 (Al, Ti) is precipitated through aging treatment to increase its strength, so Ni acts as a strengthening element. Furthermore, in order to ensure stress corrosion cracking resistance in a chlorine ion environment, which is a problem with drill collars for deep wells, a content of 25% or more is required. However, the effect of improving stress corrosion cracking resistance is
Since saturation occurs at 40%, the upper limit was set at 40%. or
Cr is required to be at least 18% to ensure corrosion resistance.
However, if it exceeds 30%, hot workability will be impaired and the austenite phase will become unstable, so the upper limit has to be set.
It was set at 30%. These appropriate ranges for Ni and Cr were determined based on the following experiments. That is, Figure 1 is a diagram showing the influence of Cr content and Ni content on stress corrosion rupture time, and these are C0.010%, Si0.5%, Mn1.2%,
The basic components are Al0.5%, Ti2.0%, Ca0.0010%, N0.005%, Ni is 30% and the amount of Cr is varied, and Cr is 20% and the amount of Ni is varied. This figure shows the results of a constant load stress corrosion cracking test using a test piece with a parallel part diameter of 6 mm under boiling conditions in saturated saline at a stress of 80 Kgf/mm 2 . As is clear from the figure, the stress corrosion rupture time is dramatically improved when Cr is 18% or more and Ni is 25% or more. Furthermore, this effect is
It is clear that Ni is already saturated at 40%. On the other hand, the effect of Cr still increases even if it exceeds 30%, but as mentioned above, it impairs hot workability, so the upper limit of Cr was set at 30%. Next, Al is an element that forms a precipitate that strengthens the steel of the present invention, that is, an intermetallic compound γ':Ni 3 (Al, Ti). It also has the effect of suppressing the precipitation of η phase, which is a grain boundary reaction type precipitate that has a detrimental effect on ductility and toughness. However, if it is added in excess, it will reduce the matching strain between the austenite phase and γ', thereby weakening the precipitation hardening effect. Therefore, the Al content was set from 0.1% to 1.5%. Additionally, Ti is the main element that forms the intermetallic compound γ′:Ni 3 (Al, Ti).
The strength increases with the amount of Ti. Drill collars need to withstand earth pressure, so they must have high strength, and to ensure that high strength, a minimum of 1.5% Ti is required. However, since adding more than 3% significantly impairs hot workability, the content was changed from 1.5% to 3%. Further, Ca is an element that improves hot workability, and requires a content of 0.0005% or more, but if it exceeds 0.020%, it deteriorates hot workability. Therefore
The Ca content was set to 0.0005 to 0.020%. Next, in the present invention, by limiting the amount of C and N, the generation of carbides or nitrides such as Ti, Cr, Mo, Nb, Zr, V, etc. is suppressed, and thereby steel materials for drill collars are This ensures the necessary ductility, toughness, and homogeneity. First, C combines with Ti during the solidification process of steel to form coarse Ti carbides. This coarse carbide is difficult to dissolve in the subsequent heating/rolling or solution heat treatment process. On the other hand, drill collars are subjected to impact forces due to changes in torque or changes in the strata during drilling, so ductility, toughness, and homogeneity of material are required to prevent damage caused by these forces. Carbides not only impair ductility and toughness but also make the material inhomogeneous. In order to prevent such coarse carbides from remaining, it is necessary to limit the amount of C to 0.015% or less. Since N is an element that is more likely than C to combine with Ti and form coarse Ti nitrides, the above C
As in the case of , it is necessary to limit this because it impairs ductility, toughness, and homogeneity, which are necessary properties for drill collars. Since N forms a compound with Ti more easily than C, it must be lower than C, with an upper limit of 0.010%. These appropriate ranges of C and N are determined based on the following effects. That is, the second
The figure shows the influence of C and N on mechanical properties; these are Si0.5%, Mn1.2%, Cr20%,
The basic components are Ni34%, Al0.5%, Ti2%, Ca0.0010%, N is 0.006%, and the amount of C is varied.
150φ by rolling or forging after melting and for those with C of 0.010% and N content varied.
After forming into a mm round steel, it was subjected to solution treatment and aging treatment, and then a JIS No. 4 tensile test piece was collected from the test piece collection position shown in the diagram in Figure 2.
This shows the results of tensile strength and elongation measurements conducted in accordance with JIS Z2241. As is clear from the figure, high yield strength and sufficient elongation are exhibited when C is 0.015% or less and N is 0.010% or less, and the yield strength and elongation values are almost the same at all sampling locations, and the material is homogeneous. Furthermore, it is clear that these mechanical properties are sufficiently satisfactory, with a yield strength of 70 Kgf/mm 2 or more and an elongation of 25% or more. This means that when C and N exceed the above values,
As mentioned above, carbonitrides are formed with Ti etc., which increases ductility and
This is because it impairs toughness. In this way, the upper limits of C and N were limited as described above. The above is the basic component system of the present invention, but in the present invention, in order to further improve the yield strength for high strength drill collars, Mo or
It is effective to contain one or more of Zr, Nb, and V within a predetermined range. First, Mo is an element that has a solid solution strengthening effect and is an effective element for increasing yield strength, but if it is added in an amount of 3% or more, the hot deformation resistance increases significantly, making rolling or forging difficult. Therefore, the content is
It was set to 3.0% or less. Furthermore, since Zr, Nb, and V are dissolved in the intermetallic compound γ' that causes precipitation strengthening, the addition of these elements increases the amount of γ' precipitated, resulting in an increase in yield strength. However, excessive addition impairs ductility and toughness, so the upper limit is set for each.
It was set at 0.5%. The steel of the present invention having the above-mentioned composition is produced by manufacturing steel using various electric furnaces, etc., and then forming into billets by ingot-forming, blooming rolling, or continuous casting, and then forming into round steel by rolling or forging. It can be made into drill collar material by solution treatment and aging treatment. The effects of the present invention will be shown in more detail below based on Examples. [Example] Table 1 shows the chemical composition and shape of the steel of the present invention and comparative steel. Table 2 shows the material properties of the steels in Table 1 at positions 20 mm and 60 mm below the surface layer of the round steel. As is clear from these property investigation results, the steel of the present invention is superior in stress corrosion cracking resistance and material homogeneity compared to comparative steels.
【表】【table】
【表】【table】
【表】【table】
以上述べたごとく、本発明鋼は耐食性とくに耐
応力耐食割れ性に優れ、しかも材質の均質性を確
保した材料となつており、環境条件の厳しい油井
用の高性能ドリルカラー用素材として工業的にき
わめて有効なものである。
As mentioned above, the steel of the present invention has excellent corrosion resistance, particularly stress corrosion and cracking resistance, and has a homogeneous material, and can be used industrially as a material for high-performance drill collars for oil wells under severe environmental conditions. It is extremely effective.
第１図は応力腐食破断時間に及ぼすCr量及び
Ni量の影響を示す図、第２図は機械的性質に及
ぼすＣとＮの影響を示す図である。
Figure 1 shows the effects of Cr content and stress corrosion rupture time.
FIG. 2 is a diagram showing the influence of the amount of Ni, and FIG. 2 is a diagram showing the influence of C and N on mechanical properties.
Claims (1)
％，Cr18〜30％，Al0.1〜1.5％，Ti1.5〜3.0％，
Ca0.0005〜0.020％を含有し、Ｃ≦0.015％，Ｎ≦
0.010％に制限し、残部がFe及び不可避不純物か
らなることを特徴とする高耐食性高強度ドリルカ
ラー用非磁性鋼。 ２ 重量％でSi≦2.0％，Mn≦2.0％，Ni25〜40
％，Cr18〜30％，Al0.1〜1.5％，Ti1.5〜3.0％，
Ca0.0005〜0.020％を含有し、Ｃ≦0.015％，Ｎ≦
0.010％に制限し、さらにMo≦3.0％を含有し、
残部がFe及び不可避不純物からなることを特徴
とする高耐食性高強度ドリルカラー用非磁性鋼。 ３ 重量％でSi≦2.0％，Mn≦2.0％，Ni25〜40
％，Cr18〜30％，Al0.1〜1.5％，Ti1.5〜3.0％，
Ca0.0005〜0.020％を含有し、Ｃ≦0.015％，Ｎ≦
0.010％に制限し、さらにZr≦0.5％，Nb≦0.5％，
Ｖ≦0.5％の１種または２種以上を含有し、残部
がFe及び不可避不純物からなることを特徴とす
る高耐食性高強度ドリルカラー用非磁性鋼。[Claims] 1. Si≦2.0%, Mn≦2.0%, Ni25-40 in weight%
%, Cr18~30%, Al0.1~1.5%, Ti1.5~3.0%,
Contains Ca0.0005-0.020%, C≦0.015%, N≦
A highly corrosion-resistant, high-strength non-magnetic steel for drill collars, limited to 0.010%, with the remainder consisting of Fe and unavoidable impurities. 2 Weight% Si≦2.0%, Mn≦2.0%, Ni25~40
%, Cr18~30%, Al0.1~1.5%, Ti1.5~3.0%,
Contains Ca0.0005-0.020%, C≦0.015%, N≦
Limited to 0.010%, further containing Mo≦3.0%,
A non-magnetic steel for use in drill collars with high corrosion resistance and high strength, characterized in that the remainder consists of Fe and unavoidable impurities. 3 Si≦2.0%, Mn≦2.0%, Ni25-40 by weight%
%, Cr18~30%, Al0.1~1.5%, Ti1.5~3.0%,
Contains Ca0.0005-0.020%, C≦0.015%, N≦
Limited to 0.010%, and further Zr≦0.5%, Nb≦0.5%,
A highly corrosion-resistant, high-strength non-magnetic steel for drill collars containing one or more of V≦0.5%, with the remainder consisting of Fe and unavoidable impurities.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59251908A JPS61130464A (en) | 1984-11-30 | 1984-11-30 | Non-magnetic steel for drill collar having superior corrosion resistance and high strength |
| DE8585308615T DE3572696D1 (en) | 1984-11-30 | 1985-11-27 | Non-magnetic steel having high corrosion resistance and high strength for use as material of drill collar, and drill collar made of the steel |
| EP85308615A EP0183536B1 (en) | 1984-11-30 | 1985-11-27 | Non-magnetic steel having high corrosion resistance and high strength for use as material of drill collar, and drill collar made of the steel |
| AT85308615T ATE45991T1 (en) | 1984-11-30 | 1985-11-27 | NON-MAGNETIC STEEL WITH HIGH CORROSION RESISTANCE AND HIGH STRENGTH FOR USE IN SAILBAR AND SAILBAR MADE OF THIS MATERIAL. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59251908A JPS61130464A (en) | 1984-11-30 | 1984-11-30 | Non-magnetic steel for drill collar having superior corrosion resistance and high strength |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61130464A JPS61130464A (en) | 1986-06-18 |
| JPH0218381B2 true JPH0218381B2 (en) | 1990-04-25 |
Family
ID=17229743
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59251908A Granted JPS61130464A (en) | 1984-11-30 | 1984-11-30 | Non-magnetic steel for drill collar having superior corrosion resistance and high strength |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0183536B1 (en) |
| JP (1) | JPS61130464A (en) |
| AT (1) | ATE45991T1 (en) |
| DE (1) | DE3572696D1 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0246092A3 (en) * | 1986-05-15 | 1989-05-03 | Exxon Research And Engineering Company | Alloys resistant to stress corrosion cracking |
| DE3907564A1 (en) * | 1989-03-09 | 1990-09-13 | Vdm Nickel Tech | NICKEL CHROME IRON ALLOY |
| CN1038353C (en) * | 1993-09-11 | 1998-05-13 | 中国科学院金属研究所 | Steel for high-strength non-magnetic drill collar |
| JP2963842B2 (en) * | 1994-06-15 | 1999-10-18 | 大同特殊鋼株式会社 | Alloy for exhaust valve |
| US6012744A (en) * | 1998-05-01 | 2000-01-11 | Grant Prideco, Inc. | Heavy weight drill pipe |
| US6372181B1 (en) | 2000-08-24 | 2002-04-16 | Inco Alloys International, Inc. | Low cost, corrosion and heat resistant alloy for diesel engine valves |
| US7651575B2 (en) | 2006-07-07 | 2010-01-26 | Eaton Corporation | Wear resistant high temperature alloy |
| CN103206175A (en) * | 2013-03-15 | 2013-07-17 | 山西北方风雷工业集团有限公司 | Drill collar with high fatigue resistance |
| CN103820736A (en) * | 2014-01-09 | 2014-05-28 | 马鞍山市恒毅机械制造有限公司 | Alloy steel material for tap hole drilling bit and preparation method of alloy steel material |
| CN115011858B (en) * | 2022-06-23 | 2023-03-17 | 沈阳航空航天大学 | High-strength high-plasticity CoCrNiAlTi multi-principal-element alloy and preparation method thereof |
| CN115466838A (en) * | 2022-09-21 | 2022-12-13 | 河南中原特钢装备制造有限公司 | Cooling method for controlling steel precipitate for non-magnetic drill collar |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2803539A (en) * | 1954-08-24 | 1957-08-20 | Jessop William & Sons Ltd | Fe-cr-ni alloys |
| AT214466B (en) * | 1959-06-04 | 1961-04-10 | Schoeller Bleckmann Stahlwerke | Steel alloys for the manufacture of drill collars for deep drill rods |
| AT308793B (en) * | 1968-12-02 | 1973-07-25 | Schoeller Bleckmann Stahlwerke | Austenitic chrome-nickel-nitrogen-steel alloy for non-magnetizable drill collar and rod parts |
| DE2117233B2 (en) * | 1971-04-08 | 1973-03-15 | Vereinigte Deutsche Metallwerke Ag, 6000 Frankfurt | USE OF A STABLE AUSTENITIC STEEL ALLOY FOR THE MANUFACTURING OF THE ARGONARE PROCESS WITHOUT ADDITIONAL MATERIALS WELDED WITHOUT WARM Cracks |
-
1984
- 1984-11-30 JP JP59251908A patent/JPS61130464A/en active Granted
-
1985
- 1985-11-27 DE DE8585308615T patent/DE3572696D1/en not_active Expired
- 1985-11-27 AT AT85308615T patent/ATE45991T1/en active
- 1985-11-27 EP EP85308615A patent/EP0183536B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0183536A2 (en) | 1986-06-04 |
| JPS61130464A (en) | 1986-06-18 |
| DE3572696D1 (en) | 1989-10-05 |
| EP0183536A3 (en) | 1987-05-13 |
| ATE45991T1 (en) | 1989-09-15 |
| EP0183536B1 (en) | 1989-08-30 |
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