JPS649392B2 - - Google Patents
Info
- Publication number
- JPS649392B2 JPS649392B2 JP18641783A JP18641783A JPS649392B2 JP S649392 B2 JPS649392 B2 JP S649392B2 JP 18641783 A JP18641783 A JP 18641783A JP 18641783 A JP18641783 A JP 18641783A JP S649392 B2 JPS649392 B2 JP S649392B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- solution treatment
- scc
- resistance
- corrosion resistance
- 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
- 230000007797 corrosion Effects 0.000 claims description 48
- 238000005260 corrosion Methods 0.000 claims description 48
- 229910052804 chromium Inorganic materials 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 10
- 229910052759 nickel Inorganic materials 0.000 claims description 9
- 229910000851 Alloy steel Inorganic materials 0.000 claims description 8
- 238000005336 cracking Methods 0.000 claims description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 229910052698 phosphorus Inorganic materials 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 33
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 16
- 230000000694 effects Effects 0.000 description 16
- 239000011651 chromium Substances 0.000 description 15
- 238000010438 heat treatment Methods 0.000 description 15
- 229910000831 Steel Inorganic materials 0.000 description 9
- 238000005097 cold rolling Methods 0.000 description 9
- 239000010959 steel Substances 0.000 description 9
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 8
- 230000006641 stabilisation Effects 0.000 description 6
- 238000011105 stabilization Methods 0.000 description 6
- 238000005098 hot rolling Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 229910052750 molybdenum Inorganic materials 0.000 description 5
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 4
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 239000011733 molybdenum Substances 0.000 description 4
- 229910052758 niobium Inorganic materials 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 238000005275 alloying Methods 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 229910000856 hastalloy Inorganic materials 0.000 description 2
- 229910001293 incoloy Inorganic materials 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 229910001629 magnesium chloride Inorganic materials 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- CADICXFYUNYKGD-UHFFFAOYSA-N sulfanylidenemanganese Chemical compound [Mn]=S CADICXFYUNYKGD-UHFFFAOYSA-N 0.000 description 2
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 2
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- BIJOYKCOMBZXAE-UHFFFAOYSA-N chromium iron nickel Chemical compound [Cr].[Fe].[Ni] BIJOYKCOMBZXAE-UHFFFAOYSA-N 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000011376 self-consolidating concrete Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000011592 zinc chloride Substances 0.000 description 1
- 235000005074 zinc chloride Nutrition 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Description
本発明は耐食性及び耐応力腐食割れ性に優れた
合金鋼の製造方法に関する。
金属材料が使われる腐食環境は、近年その苛酷
度が増す傾向にあり、例えば、油井、ガス井や地
熱井等ではその深井戸化に伴い井戸底部での高
温、高圧化、塩化物の高濃度化が進み、加えて硫
化水素、炭酸ガス等も高濃度化しつつある。この
ような腐食環境条件の変化に対応し、そこで使用
される耐食性材料も従来の９％クロム鋼、13％ク
ロム鋼、18％クロム鋼或はSUS304，316クラス
の鉄鋼材料等から、例えばインコロイ、ハステロ
イ等で知られる高合金鋼の使用が検討されつつあ
る。ところで、このような苛酷化した腐食環境で
の高合金材料の腐食現象は、孔食や応力腐食割れ
（以下「SCC」と称す）のような局部腐食に代表
される。このような局部腐食に及ぼす合金元素の
影響として最も一般的に知られるものは、SCCに
対してはニツケル、孔食に対してはクロムとモリ
ブデンである。18％程度のクロムを含有するクロ
ム−ニツケル−鉄系合金の塩化マグネシウム溶液
中における耐SCC性は、８％ニツケルで最も劣
り、ニツケル添加量の減少或は高ニツケル化によ
り向上することが知られており、特にニツケル含
有量を45％以上にすることにより極めて高い耐
SCCが得られる。また耐孔食性はクロム含有量が
増すことによつて向上し、約22以上のクロム含有
量により耐孔食性が極めて高くなることが知られ
ている。さらにモリブデンは、クロムと同時添加
によりその効果を示し、クロムの1.5倍程度の効
力を示す。しかしながら、以上述べたような各成
分元素の影響は、主として着目成分濃度のみを変
動因子としており、成分元素相互の作用について
は、従来ほとんど検討されておらず、またSCC性
や耐食性を同時に検討した例もほとんどみられな
い。すなわち、耐食性高合金の成分設計は、耐
SCC性向上の為にニツケルの添加量を増し、耐孔
食性を高めるためクロムとモリブデンを増す傾向
にあるが、各々の合金元素の添加量は、個別元素
の個別現象への効果を基に定められており、耐
SCC性と耐孔食性向上のためにニツケル、クロ
ム、モリブデン等の相互最適バランスを定量的に
考慮した材料は末だ知られておらず、また、実際
の製品製造において、特に溶体化処理条件と耐
SCC性、耐孔食性との関係についても十分な解明
がなされていないのが現状である。
本発明はこのような現状に鑑み創案されたもの
で、耐SCC性及び耐孔食性に対する合金元素の相
互作用及びこれと溶体化（又は準溶体化）処理条
件との関係を解明し、従来の所謂インコロイやハ
ステロイよりも更に優れた耐孔食性と耐応力腐食
割れ性を有する高合金鋼を得ることに成功したも
のである。
即ち、本発明においては、Ｃ：0.015wt％以下、
Si：1wt％以下、Mn：1wt％以下、Ｐ：0.01wt％
以下、Ｓ：0.01wt％以下、Ni：60wt％超〜70wt
％、Cr：22〜35wt％、Mo：10wt％以下、Ｎ：
0.01wt％以下、Cu：1wt％以下、及び1wt％以下
のTi、1wt％以下のNb、0.1wt％以下のCaを１種
又は２種以上含有し、残部鉄及び不可避不純物か
らなる組成であつて、
Δ1＝〔Cr＋1.5Mo＋0.8Ti＋0.5Cu−100C〕
で求められるΔ1の値が25（％）以上である組成を
有する合金鋼を、950〜1250℃の温度範囲であつ
て且つ下式の条件を満たす温度Tfにて溶体化又
は準溶体化処理するようにしたものである。
Δ2＝Ni−〔｛（Cr＋1.5Mo−20）2／12｝
−35C−27N＋14〕
Tf60Δ2−550
以下本発明の成分組成及び熱処理条件の限定理
由を詳細に説明する。
本発明の成分組成の限定理由は以下の通りであ
る。
C′は粒内型SCCの抑制に対して有効との説もあ
るが、炭素含有量が高くなると粒界型SCCを起こ
し易くなり、特に炭素固溶度が減少する高Ni合
金でそのおそれが大きくなる。また炭化物の析出
物は孔食の起点になり易いという問題があり、こ
のようなことからＣはその上限が0.015wt％以下
に制限される。
Siは脱酸成分として必要であるが、熱間加工性
を劣化させる成分であり、このような問題を生じ
させないためその上限が１％と定められる。
MnはSiと同様脱酸作用がある。このMnは耐
SCC性にはほとんど影響を与えないが、１％を超
えるとマンガン硫化物等の析出物が孔食の起点と
なり易く、従つてその上限が１％と定められる。
不可避不純物としてのＰはSCC感受性を高める
作用があるため極力低減させる必要があり、この
ためその上限が0.01wt％と定められる。
不可避不純物としてのＳには熱間加工性を劣化
させる作用があり、マンガン硫化物等を作つて耐
孔食性を悪化するので、その上限が0.01wt％と定
められる。
Niは耐SCC性を向上させるのに有効な元素で
あり、20wt％以上の含有量でその効果が顕著に
なるが、Cr量を増すと耐SCC性は低下するので、
十分な耐食性を満足するCr量に対して優れた耐
SCC性を示すようにするには少なくとも60wt％
を超えて含有せしめることが必要であり、その下
限が60wt％超と定められる。また、他の成分、
特にCr量との関係で、70wt％が上限となる。
Crは高合金鋼の耐食性、特に不働態皮膜の強
化による耐食性向上に有効な元素である。十分な
耐食性を得るためには22wt％以上の含有量が必
要であるが、この含有量が35wt％を超えると熱
間加工性の劣化が避け難く、このためその含有量
は22〜35wt％と定められる。
Moは不働態皮膜の強化に対してCrの1.5倍程度
の効果があるが、その含有量が10wt％を超える
と熱間工程時に耐食性を劣化させるσ相を容易に
生成するようになり、このためその上限が10wt
％と定められる。
Ｎは耐孔食性を向上させるが、本発明鋼では窒
素成分がなくても十分な耐孔食性がある。逆にＮ
は0.01wt％を超えると耐SCC性に悪影響を与える
ものであり、このためその上限が0.01wt％と定め
られる。
Cuは材料の耐食性を向上させるのに役立つが、
1wt％を超えると熱間加工性の劣化を招き、この
ため1wt％が上限と定められる。
Ca，Ti，Nbの各成分は熱間加工性を向上させ
る作用があり、さらにTiとNbは炭素を固定し、
結果的に粒界SCCを抑制する効果をもつ。各々の
成分がこのような効果を発揮するのに、Caは
0.1wt％以下、Ti及びNbはそれぞれ1wt％以下で
あれば十分であり、この上限を超えて含有せしめ
てもそれ以上の効果は期待できない。これらの成
分は、その１種又は２種以上が含有せしめられ
る。
本発明では、以上のような成分元素の組成条件
に、さらに成分元素間での次のような条件を満足
させる必要があり、このような成分元素相互の関
係を満足させることによつて、本発明が目的とす
る優れた耐孔食性が得られる。すなわち、本発明
では、
Δ1＝〔Cr＋1.5Mo＋0.8Ti＋0.5Cu−100C〕
の式で定義されるΔ1値が25以上となるよう各成
分値が調整される必要がある。第１図は厳しい腐
食環境下での耐孔食性に関し、Δ1値と孔食速度
との関係を調べたものであり、Cr，Ni，Mo等の
含有量を変化させた合金について10％塩化第二鉄
系の孔食実験を行つた結果を示したものである。
同図から明らかなように、上記本発明の採用する
成分組成にあつてもΔ1＜25の範囲では耐孔食性
が大きく劣り、耐孔食性を十分満足させるには成
分元素の相互的な関係を満たすことが不可欠であ
ることが判る。
本発明では上記した成分条件の鋼を溶製した
後、熱間圧延以降の工程で所謂溶体化処理又は準
溶体化処理が行われる。ここで準溶体化処理と
は、完全とはいかないまでも組織中のカーバイト
の溶解が進行し成分元素の不均一が均一化される
状態となるような処理を指す。そして本発明で
は、まず、かかる熱処理を950〜1250℃の温度範
囲で行うことが条件とされる。ここで熱処理温度
が950℃未満では金属組成の均一化が必要とされ
る程度まで得られないため十分な耐SCC性が期待
できず、また、1250℃を超えた熱処理も耐SCC性
の低下をもたらすため好ましくない。成分組成に
よつて差はあるが、一般的にはこのような950〜
1250℃の温度範囲中、高温側での熱処理が溶体化
処理、低温側での熱処理が準溶体化処理となる。
本発明の熱処理は、このような温度範囲において
更に下式の条件を満たす温度Tfで行うことが条
件とされる。
Δ2＝Ni−〔｛（Cr＋1.5Mo−20）2／12｝
−35C−27N＋14〕
Tf60Δ2−550
温度Tfは成分元素相互の含有量に関係して求
められるΔ2値に基づき決定されるもので、この
ように成分元素の相互的な関係から決定される温
度で溶体化処理又は準溶体化処理を行うことによ
り、本発明の目的とする優れた耐SCC性が得られ
る。第２図は厳しい腐食環境下においてΔ2値と
熱処理温度Tfとの関係から耐SCC性を調べたも
のであり、具体的には、塩化マグネシウムより腐
食性が厳しい塩化亜鉛溶液中でSCC試験を行い
600時間の割れの有無で耐SCC性を判定したもの
である。同図からも明らかなように、950〜1250
℃の温度範囲であつても、Δ2値との関係からTf
＞60Δ2−550の範囲では耐応力腐食割れ性が劣
り、耐応力腐食割れ性を十分満足させるには成分
元素相互の関係で求められるΔ2の値に基づいた
温度で熱処理することが不可欠であることが判
る。なお、図中破線で示すように、本発明では実
質的にΔ2の値が少なくとも25以上であることが
必要とされる。
上記した溶体化処理又は準溶体化処理は、熱間
加工以降の種々の段階で行うことができ例えば、
熱間圧延−冷間圧延−溶体化処理又は準溶体化
処理、熱間圧延−溶体化処理又は準溶体化処理
−冷間圧延、等の各工程を採ることができる。ま
た、溶体化処理（若しくは準溶体化処理）後、固
溶Ｃを過飽和の状態から飽和状態にして組織の安
定化を図るための熱処理、所謂安定化処理を行う
ことができ、この場合には、例えば、熱間圧延
−溶体化処理−冷間圧延−安定化処理、熱間圧
延−溶体化処理−安定化処理−冷間圧延、熱間
圧延−冷間圧延−溶体化処理−冷間圧延−安定化
処理、等の各工程を採ることができる。ここで上
記準溶体化処理は、組織中のカーバイドの溶解を
ある程度進行せしめ、これによつて成分元素の均
一化（ミクロ的な成分濃度の均一化を含む）が図
られるようにした熱処理であることは前述した通
りであり、このようにして得られる組織は溶体化
処理−安定化処理を経て均一化、安定化された組
織に近いものとなる。なお、上記した、で示
すような工程では、溶体化処理と安定化処理の工
程間で冷間圧延が行われ、この冷間圧延によつて
NbC、TiC等の析出が促進されるため、より安定
化した組織を得ることができる。
〔実施例〕
第１表に本発明鋼（Ｃ−１〜Ｃ−11）及び比較
鋼（Ｄ−１〜Ｄ−８）の化学成分を示す。これら
はいずれも通常のステンレス鋼の製造ラインで製
造されたもので、熱間圧延−焼鈍−冷間圧延後、
950〜1250℃の温度範囲で10〜30分間加熱して急
冷する溶体化処理又は準溶体化処理を行つた。な
お、いくつかの条件では上記焼鈍工程に相当する
段階で溶体化処理又は準溶体化処理を行い、冷間
圧延後の熱処理を省略した。工程上における熱処
理の位置或いは当該熱処理における保持時間は結
果に影響を与えないので、それらの項目は省略し
た。各供試鋼の耐孔食性及び耐SCC性に関する試
験結果を第１表に併せて示した。
The present invention relates to a method for manufacturing alloy steel having excellent corrosion resistance and stress corrosion cracking resistance. The corrosive environments in which metal materials are used have tended to become more severe in recent years. For example, as oil wells, gas wells, and geothermal wells become deeper, the bottoms of the wells are exposed to higher temperatures, higher pressures, and higher concentrations of chlorides. In addition, the concentration of hydrogen sulfide, carbon dioxide, etc. is increasing. In response to these changes in corrosive environmental conditions, the corrosion-resistant materials used have changed from the conventional 9% chromium steel, 13% chromium steel, 18% chromium steel, or SUS304, 316 class steel materials to, for example, Incoloy, The use of high-alloy steels such as Hastelloy is being considered. Incidentally, corrosion phenomena of high alloy materials in such a severe corrosive environment are typified by localized corrosion such as pitting corrosion and stress corrosion cracking (hereinafter referred to as "SCC"). The most commonly known effects of alloying elements on such localized corrosion are nickel for SCC and chromium and molybdenum for pitting. It is known that the SCC resistance of a chromium-nickel-iron alloy containing about 18% chromium in a magnesium chloride solution is the worst at 8% nickel, and can be improved by reducing the amount of nickel added or increasing the nickel content. In particular, by increasing the nickel content to 45% or more, extremely high durability can be achieved.
SCC is obtained. It is also known that pitting corrosion resistance is improved by increasing the chromium content, and that pitting corrosion resistance becomes extremely high with a chromium content of about 22 or more. Furthermore, molybdenum exhibits its effect when added simultaneously with chromium, and exhibits an effect that is approximately 1.5 times that of chromium. However, the influence of each component element as described above mainly has only the concentration of the component of interest as a variable factor, and the interaction of the component elements has hardly been studied in the past, and SCC properties and corrosion resistance have not been studied at the same time. There are very few examples. In other words, the composition design of highly corrosion-resistant alloys
There is a tendency to increase the amount of nickel added to improve SCC properties, and to increase chromium and molybdenum to improve pitting corrosion resistance, but the amount of each alloying element added is determined based on the effect of each element on individual phenomena. It has been
There are still no known materials that quantitatively consider the optimal balance of nickel, chromium, molybdenum, etc. to improve SCC properties and pitting corrosion resistance. Endurance
At present, the relationship between SCC property and pitting corrosion resistance has not been fully elucidated. The present invention was devised in view of the current situation, and aims to elucidate the interaction of alloying elements with respect to SCC resistance and pitting corrosion resistance and the relationship between this and solution treatment (or quasi-solution treatment) treatment conditions, thereby improving the conventional method. This work has succeeded in producing a high-alloy steel that has even better pitting corrosion resistance and stress corrosion cracking resistance than so-called Incoloy and Hastelloy. That is, in the present invention, C: 0.015wt% or less,
Si: 1wt% or less, Mn: 1wt% or less, P: 0.01wt%
Below, S: 0.01wt% or less, Ni: more than 60wt% ~ 70wt
%, Cr: 22-35wt%, Mo: 10wt% or less, N:
0.01wt% or less, Cu: 1wt% or less, and one or more types of Ti, 1wt% or less Nb, and 0.1wt% or less Ca, with the balance consisting of iron and unavoidable impurities. Then, an alloy steel having a composition in which the value of Δ 1 determined by Δ 1 = [Cr + 1.5 Mo + 0.8 Ti + 0.5 Cu − 100 C] is 25 (%) or more is heated in the temperature range of 950 to 1250 °C and below. Solution treatment or quasi-solution treatment is performed at a temperature Tf that satisfies the conditions of the formula. Δ 2 =Ni− [{(Cr+1.5Mo−20) 2 /12} −35C−27N+14] Tf60Δ 2 −550 The reasons for limiting the component composition and heat treatment conditions of the present invention will be explained in detail below. The reasons for limiting the component composition of the present invention are as follows. There is a theory that C' is effective in suppressing intragranular SCC, but as the carbon content increases, grain boundary SCC is more likely to occur, especially in high-Ni alloys where carbon solid solubility decreases. growing. Further, there is a problem that carbide precipitates tend to become a starting point for pitting corrosion, and for this reason, the upper limit of C is limited to 0.015 wt% or less. Although Si is necessary as a deoxidizing component, it is a component that deteriorates hot workability, and its upper limit is set at 1% to avoid such problems. Like Si, Mn has a deoxidizing effect. This Mn is
Although it has little effect on SCC properties, if it exceeds 1%, precipitates such as manganese sulfide tend to become a starting point for pitting corrosion, so the upper limit is set at 1%. Since P as an unavoidable impurity has the effect of increasing SCC sensitivity, it must be reduced as much as possible, and therefore the upper limit is set at 0.01 wt%. S as an unavoidable impurity has the effect of deteriorating hot workability and creates manganese sulfide, etc., which deteriorates pitting corrosion resistance, so the upper limit of S is set at 0.01 wt%. Ni is an effective element for improving SCC resistance, and its effect becomes noticeable when the content is 20wt% or more, but as the amount of Cr increases, SCC resistance decreases.
Excellent resistance to the amount of Cr that satisfies sufficient corrosion resistance.
At least 60wt% to exhibit SCC properties
The lower limit is set at more than 60wt%. In addition, other ingredients,
Especially in relation to the Cr content, the upper limit is 70wt%. Cr is an effective element for improving the corrosion resistance of high alloy steel, especially by strengthening the passive film. In order to obtain sufficient corrosion resistance, a content of 22wt% or more is required, but if this content exceeds 35wt%, it is difficult to avoid deterioration of hot workability, so the content is limited to 22 to 35wt%. determined. Mo is about 1.5 times as effective as Cr in strengthening the passive film, but if its content exceeds 10wt%, it easily forms a σ phase that deteriorates corrosion resistance during hot processing. Therefore, the upper limit is 10wt
%. Although N improves pitting corrosion resistance, the steel of the present invention has sufficient pitting corrosion resistance even without a nitrogen component. On the contrary, N
If it exceeds 0.01wt%, it will have an adverse effect on SCC resistance, and therefore the upper limit is set at 0.01wt%. Although Cu helps improve the corrosion resistance of materials,
If it exceeds 1wt%, hot workability deteriorates, and for this reason, 1wt% is set as the upper limit. Each component of Ca, Ti, and Nb has the effect of improving hot workability, and Ti and Nb also fix carbon,
As a result, it has the effect of suppressing grain boundary SCC. Although each component exerts such an effect, Ca
It is sufficient if the content of Ti and Nb is 0.1 wt% or less, and each of Ti and Nb is 1 wt% or less, and even if the content exceeds this upper limit, no further effect can be expected. One or more of these components may be contained. In the present invention, it is necessary to satisfy the compositional conditions of the component elements as described above, as well as the following conditions between the component elements. The excellent pitting corrosion resistance aimed at by the invention can be obtained. That is, in the present invention, each component value needs to be adjusted so that the Δ 1 value defined by the formula Δ 1 = [Cr+1.5Mo+0.8Ti+0.5Cu−100C] becomes 25 or more. Figure 1 shows the relationship between the Δ1 value and pitting corrosion rate regarding pitting corrosion resistance under severe corrosive environments. This shows the results of a ferric iron pitting corrosion experiment.
As is clear from the figure, even with the component composition adopted by the present invention, the pitting corrosion resistance is greatly inferior in the range of Δ 1 < 25, and the mutual relationship between the component elements is necessary to fully satisfy the pitting corrosion resistance. It turns out that it is essential to satisfy the following. In the present invention, after the steel having the above-mentioned compositional conditions is melted, so-called solution treatment or semi-solution treatment is performed in the steps after hot rolling. Here, the quasi-solution treatment refers to a treatment in which the dissolution of carbide in the structure progresses, although not completely, and the non-uniformity of the component elements becomes uniform. In the present invention, first, it is a condition that such heat treatment is performed at a temperature range of 950 to 1250°C. If the heat treatment temperature is less than 950°C, sufficient SCC resistance cannot be expected because the metal composition cannot be made uniform to the required degree, and heat treatment at temperatures exceeding 1250°C may also cause a decrease in SCC resistance. undesirable because it causes Although there are differences depending on the ingredient composition, generally 950 ~
In the temperature range of 1250°C, heat treatment on the high temperature side is solution treatment, and heat treatment on the low temperature side is quasi-solution treatment.
The heat treatment of the present invention is conditioned to be performed at a temperature Tf that further satisfies the condition of the following formula within such a temperature range. Δ 2 = Ni− [{(Cr+1.5Mo−20) 2 /12} −35C−27N+14] Tf60Δ 2 −550 Temperature Tf is determined based on the Δ 2 value determined in relation to the content of each component element. By performing solution treatment or quasi-solution treatment at a temperature determined from the mutual relationship of the component elements, the excellent SCC resistance that is the object of the present invention can be obtained. Figure 2 shows the investigation of SCC resistance from the relationship between Δ 2 value and heat treatment temperature Tf in a severe corrosive environment. Specifically, the SCC test was conducted in a zinc chloride solution, which is more corrosive than magnesium chloride. conduct
SCC resistance was determined based on the presence or absence of cracks after 600 hours. As is clear from the figure, 950 to 1250
Even in the temperature range of ℃, Tf
In the range >60Δ 2 -550, stress corrosion cracking resistance is poor, and in order to fully satisfy stress corrosion cracking resistance, it is essential to heat treat at a temperature based on the Δ 2 value determined from the relationship between the component elements. It turns out that there is something. Note that, as shown by the broken line in the figure, the present invention substantially requires that the value of Δ 2 be at least 25 or more. The solution treatment or quasi-solution treatment described above can be performed at various stages after hot working, and for example,
Each process such as hot rolling-cold rolling-solution treatment or quasi-solution treatment, hot rolling-solution treatment or quasi-solution treatment-cold rolling, etc. can be adopted. Furthermore, after the solution treatment (or quasi-solution treatment), a so-called stabilization treatment can be performed, which is a heat treatment to stabilize the structure by changing the solid solution C from a supersaturated state to a saturated state. , for example, hot rolling - solution treatment - cold rolling - stabilization treatment, hot rolling - solution treatment - stabilization treatment - cold rolling, hot rolling - cold rolling - solution treatment - cold rolling. - It is possible to take various steps such as stabilization treatment. Here, the quasi-solution treatment is a heat treatment that progresses the dissolution of carbide in the structure to a certain extent, thereby achieving uniformity of component elements (including uniformity of microscopic component concentration). This is as described above, and the structure obtained in this manner becomes similar to a homogenized and stabilized structure through solution treatment and stabilization treatment. In addition, in the process shown above, cold rolling is performed between the solution treatment and stabilization treatment, and this cold rolling
Since the precipitation of NbC, TiC, etc. is promoted, a more stable structure can be obtained. [Example] Table 1 shows the chemical components of the invention steels (C-1 to C-11) and comparative steels (D-1 to D-8). All of these were manufactured on a normal stainless steel production line, and after hot rolling, annealing, and cold rolling,
Solution treatment or quasi-solution treatment was performed by heating in a temperature range of 950 to 1250°C for 10 to 30 minutes and rapidly cooling. Note that under some conditions, solution treatment or quasi-solution treatment was performed at a stage corresponding to the annealing step, and heat treatment after cold rolling was omitted. Since the position of the heat treatment in the process or the holding time in the heat treatment do not affect the results, these items were omitted. Test results regarding pitting corrosion resistance and SCC resistance of each sample steel are also shown in Table 1.
【表】【table】
【表】
(注) ＊…孔食試験結果：○良、●不良
＊＊…応力腐食割れ試験結果(600時間後)：
○破断せず、●破断
同表からも明らかなように、本発明鋼は耐孔食
性と耐SCC性を同時に満足させた優れた性質を有
しているのに対し、比較鋼では耐孔食性と耐SCC
性のいずれか一方、又は双方に悪影響を生じてい
ることが判る。
以上述べたように本発明によれば、耐孔食性及
び耐応力腐食割れ性と成分組成及びそれらの相互
関係、さらにはかかる成分条件と熱処理条件との
関係を解明し、それらを特定の範囲に選定するこ
とにより、従来にない優れた耐孔食性と耐SCC性
の合金鋼の製造を可能ならしめたものであつて、
この種合金鋼に関する工業的な効果の大きい発明
である。[Table] (Note) *…Pitting corrosion test results: ○Good, ●Poor **…Stress corrosion cracking test results (after 600 hours):
○ No fracture, ● Fracture As is clear from the table, the steel of the present invention has excellent properties that satisfy both pitting corrosion resistance and SCC resistance, whereas the comparative steel has poor pitting corrosion resistance. and SCC resistance
It can be seen that there is an adverse effect on one or both sexes. As described above, according to the present invention, the pitting corrosion resistance, stress corrosion cracking resistance, component composition, and their mutual relationship, as well as the relationship between such component conditions and heat treatment conditions, are clarified, and they are adjusted to a specific range. By selecting this material, it is possible to manufacture alloy steel with unprecedented pitting corrosion resistance and SCC resistance.
This invention has great industrial effects regarding this type of alloy steel.
第１図はΔ1値と孔食速度（耐孔食性）との関
係を示すものである。第２図はΔ2値と溶体化処
理（又は準溶体化処理）との関係を示すものであ
る。
FIG. 1 shows the relationship between the Δ1 value and the pitting corrosion rate (pitting corrosion resistance). FIG. 2 shows the relationship between the Δ 2 value and solution treatment (or quasi-solution treatment).
Claims (1)
1wt％以下、Ｐ：0.01wt％以下、Ｓ：0.01wt％以
下、Ni：60wt％超〜70wt％、Cr：22〜35wt％、
Mo：10wt％以下、Ｎ：0.01wt％以下、Cu：1wt
％以下、さらにこれらに加えて1wt％以下のTi、
1wt％以下のNb、0.1wt％以下のCaのうちの１種
又は２種以上を含有し、残部鉄及び不可避不純物
からなる組成であつて、 Δ1＝〔Cr＋1.5Mo＋0.8Ti＋0.5Cu−100C〕 で求められるΔ1の値が25以上である組成を有す
る合金鋼を、950〜1250℃の温度範囲であつて且
つ下式の条件を満たす温度Tfにて溶体化又は準
溶体化処理することを特徴とする耐食性及び耐応
力腐食割れ性に優れた合金鋼の製造方法。 Δ2＝Ni−〔｛（Cr＋1.5Mo−20）2／12｝ −35C−27N＋14〕 Tf60Δ2−550[Claims] 1 C: 0.015wt% or less, Si: 1wt% or less, Mn:
1wt% or less, P: 0.01wt% or less, S: 0.01wt% or less, Ni: more than 60wt% to 70wt%, Cr: 22 to 35wt%,
Mo: 10wt% or less, N: 0.01wt% or less, Cu: 1wt
% or less, and in addition to these, Ti of 1wt% or less,
A composition containing one or more of Nb of 1wt% or less and Ca of 0.1wt% or less, and the balance consisting of iron and inevitable impurities, Δ 1 = [Cr + 1.5Mo + 0.8Ti + 0.5Cu - 100C ] Solution treatment or quasi-solution treatment of alloy steel having a composition in which the value of Δ 1 determined by A method for producing alloy steel with excellent corrosion resistance and stress corrosion cracking resistance. Δ 2 = Ni− [{(Cr+1.5Mo−20) 2 /12} −35C−27N+14] Tf60Δ 2 −550
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18641783A JPS6077916A (en) | 1983-10-05 | 1983-10-05 | Manufacture of alloy steel having superior resistance to corrosion and stress corrosion cracking |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18641783A JPS6077916A (en) | 1983-10-05 | 1983-10-05 | Manufacture of alloy steel having superior resistance to corrosion and stress corrosion cracking |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6077916A JPS6077916A (en) | 1985-05-02 |
| JPS649392B2 true JPS649392B2 (en) | 1989-02-17 |
Family
ID=16188055
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18641783A Granted JPS6077916A (en) | 1983-10-05 | 1983-10-05 | Manufacture of alloy steel having superior resistance to corrosion and stress corrosion cracking |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6077916A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0689426B2 (en) * | 1985-07-06 | 1994-11-09 | バブコツク日立株式会社 | Nickel base alloy |
-
1983
- 1983-10-05 JP JP18641783A patent/JPS6077916A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6077916A (en) | 1985-05-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4652315A (en) | Precipitation-hardening nickel-base alloy and method of producing same | |
| US4295769A (en) | Copper and nitrogen containing austenitic stainless steel and fastener | |
| JP5225855B2 (en) | High-strength corrosion-resistant alloy for oil patch application and method for producing the same | |
| JP2007284799A (en) | Corrosion-resistant austenitic stainless steel | |
| DE69506537T2 (en) | STAINLESS STEEL TWO-PHASE STEEL | |
| US5288347A (en) | Method of manufacturing high strength and high toughness stainless steel | |
| CA1149646A (en) | Austenitic stainless corrosion-resistant alloy | |
| US4371394A (en) | Corrosion resistant austenitic alloy | |
| JPS649391B2 (en) | ||
| JP4207137B2 (en) | High hardness and high corrosion resistance stainless steel | |
| US4502886A (en) | Austenitic stainless steel and drill collar | |
| JPH02217445A (en) | Improved austenite fe-cr-ni alloy for oil well field tube products | |
| JPH0726350A (en) | Austenitic stainless steel excellent in pitting corrosion resistance and its production | |
| JPS6048582B2 (en) | Stainless steel for razor blades with high heat treatment hardness | |
| JPS625986B2 (en) | ||
| JPS61119641A (en) | Highly corrosion-resistant ni-base alloy and its production | |
| JPH0114992B2 (en) | ||
| JPS649392B2 (en) | ||
| JPS62158849A (en) | Highly corrosion resistant ni-base alloy excellent in toughness | |
| JPH01215491A (en) | Covered arc welding electrode for cr-mo low alloy steel | |
| JPS602653A (en) | Production of precipitation hardening type nickel-base alloy | |
| KR100215727B1 (en) | Super duplex stainless steel with high wear-resistance | |
| JPS5980755A (en) | Chrome-molybdenum steel having superior temper embrittlement resistance at weld heat-affected zone | |
| JPH0352527B2 (en) | ||
| JPS6240345A (en) | High tension steel pipe for oil well having superior delayed fracture resistance |