JP3921809B2 - Method for producing martensitic stainless steel pipe with excellent low temperature toughness - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、低温靭性に優れたマルテンサイト系ステンレス鋼の製造方法に関するものである。
【０００２】
【従来の技術】
マルテンサイト系ステンレス鋼は、ＡＩＳＩ４２０鋼に代表されるように、強度、耐ＣＯ2腐食性に優れ比較的安価であることから１９８０年頃より油井管として適用されてきた。通常は製管後，焼き入れ・焼戻し処理して製造されるが、低温靭性が不十分であるため寒冷地での使用が制限されている。そこで，優れた低温靭性を得るための製造方法として、特開平３−７５３０８号公報などに見られるような、オーステナイト化後の冷却速度を大きくし粗大クロム炭化物の析出を抑制する製造方法や、特開平５−２６３１３４号公報などに見られるような、焼戻し後の冷却速度を大きくし粗大クロム炭化物の析出を抑制する製造方法や、特開平４−２１０４５３号公報などに見られるようなオーステナイト化時の昇温速度を大きくしかつ保定時間を短くしてオーステナイト粒径の粗大化を防止する製造方法や、特開昭６３−２３８２１７号公報や特開昭６３−２４１１１７号公報などに見られるように加工熱処理法を利用する製造方法などが提案されている。しかしながら、これらの策をとってもなお降伏応力が６５０ＭＰａを超える高強度材においては十分な低温靭性が得られていないのが現状である。
【０００３】
【発明が解決しようとする課題】
本発明は、上記したような問題点を解決しようとするものであって、降伏応力が６５０ＭＰａを超える高強度を有しかつ優れた低温靭性を有するマルテンサイト系ステンレス鋼の製造方法を提供することを目的とする。
【０００４】
【課題を解決するための手段】
本発明者らは、成分の異なる種々の素材に対して種々の熱処理を行い、低温靭性について研究を重ねた結果、Ｃを０．１０％以上０．１８％以下，Ｎｉを１％以上３％以下に調整した１３％Ｃｒ鋼を熱間圧延法により造管した後、Ａｃ 1 点以上Ａｃ 3 点以下の温度に加熱し続いて室温まで空冷以上の速度で冷却するとマルテンサイト母相中に残留オーステナイトが微細に分散した組織となり、これをＡｃ 1 点以下の温度で焼戻し処理すると低温靭性が大幅に向上することと、上記成分範囲内であれば熱間加工性を劣化させるδフェライトの析出を防止できることを知見した。
【０００５】
本発明はこのような知見に基づいて構成したものであり，その要旨とするところは、重量％で、
Ｃ ：０．１０〜０．１８％、 Ｓｉ：０．５％以下、
Ｍｎ：０．１〜１．５％以下、 Ｐ ：０．０２％以下、
Ｓ ：０．０１％以下、 Ｃｒ：１２〜１４％、
Ｎｉ：１〜３％、 Ａｌ：０．３以下％、
Ｎ ：０．００１〜０．０８％
を含有し、さらに，必要に応じて、
Ｍｏ：０．５％以下、 Ｃｕ：１．５％以下、
Ｔｉ：０．００１〜０．０５％、 Ｃａ：０．００１〜０．０１％
の１種または２種以上を含有し，残部がＦｅ及び不可避的不純物からなるマルテンサイト系ステンレス鋼を熱間圧延法により造管した後、必要に応じてＡｃ 3 点以上９５０℃以下の温度域に加熱し続いて室温まで空冷以上の速度で冷却し、Ａｃ 1 点以上Ａｃ 3 点以下の温度に加熱し続いて室温まで空冷以上の速度で冷却し、しかる後、Ａｃ 1 点以下の温度で焼戻し処理することを特徴とする低温靭性に優れたマルテンサイト系ステンレス鋼管の製造方法である。
【０００６】
【発明の実施の形態】
以下、本発明について詳細に説明する。マルテンサイト系ステンレス鋼の代表的鋼種であるＡＩＳＩ４２０鋼（０．２％Ｃ−１３％Ｃｒ）をＡｃ 1 点以上Ａｃ 3 点以下の温度に加熱すると逆変態オーステナイトが生成するが、続いて室温まで空冷以上の速度で冷却すると逆変態したオーステナイトはマルテンサイトに変態するため残留オーステナイトはほとんど生成しない。ところがＣ量を０．１８％以下に低減し、オーステナイト安定化元素であるＮｉを１％以上添加した成分の鋼をＡｃ 1 点以上Ａｃ 3 点以下の温度に加熱すると逆変態したオーステナイト相中にＮｉが濃化しオーステナイトの安定性が高くなるため、室温まで空冷以上の速度で冷却してもオーステナイトが保持される。すなわち、マルテンサイト母相中に残留オーステナイトが微細に分散した組織となる。これをＡｃ 1点以下の温度で焼戻し処理すると低温靭性が大幅に向上する。逆変態したオーステナイトの安定性を向上させるにはＮｉ量は多いほどよいが、多すぎると、Ａｃ 1 点が低下し強度調質可能範囲が制限されるので、Ｎｉ添加量の上限を３％とした。Ａｃ 1 点以上Ａｃ 3 点以下の温度に加熱して逆変態したマルテンサイトを室温まで冷却するときにマルテンサイト変態するのを防止するためにはＣ量は低いほどよいが、熱間加工性を劣化させるδフェライトの生成を防止するため下限を０．１％とした。
【０００７】
熱間圧延法により造管した後、Ａｃ 1 点以上Ａｃ 3 点以下の温度に加熱し続いて室温まで空冷以上の速度で冷却する熱処理を行う前に、Ａｃ 3 点以上９５０℃以下の温度域に加熱し続いて室温まで空冷以上の速度で冷却する熱処理を行うと、低温靭性を一層向上させることができる。これは、熱間圧延法により造管した後オーステナイトと未固溶炭化物の共存温度域に加熱し続いて室温まで空冷以上の速度で冷却すると、未固溶炭化物の粒界ピンニングによるオーステナイト粒成長の抑制効果によりオーステナイト粒径を細粒化することができ、また、固溶炭素が少ないので空冷以上の速度で冷却すると粒界への粗大クロム炭化物の析出を抑制できるからである。
【０００８】
必要に応じてＡｃ 3 点以上９５０℃以下の温度域に加熱し続いて室温まで空冷以上の速度で冷却し、Ａｃ 1 点以上Ａｃ 3 点以下の温度に加熱し続いて室温まで空冷以上の速度で冷却したマルテンサイトと残留オーステナイトの２相混合組織を、Ａｃ 1 点以下の温度で焼戻し処理すると所要の強度・靭性が得られるが、焼戻し温度がＡｃ 1 点を超えると降伏応力が急激に低下するため強度を安定的に造り込むことができない。それゆえ焼戻し温度をＡｃ 1 点以下とした。
【０００９】
本発明におけるマルテンサイト系ステンレス鋼管の成分限定理由は以下の通りである。
Ｃ：Ｃは０．１８％を超えると耐食性及び靭性の劣化が生じるので上限を０．１８％とした。また、０．１０％より少ないと熱間加工温度域でδフェライトが析出して熱間加工性を劣化させるので加減を０．１０％とした。
【００１０】
Ｓｉ：Ｓｉは製鋼工程において脱酸剤として添加されるものである。０．５％を越えて含有されると靭性が劣化することから、上限を０．５％とした。
【００１１】
Ｍｎ：Ｍｎはオーステナイト安定化元素であり、熱間加工時にδフェライトの析出を抑制することにより圧延疵防止に有効であるが、０．１％未満ではその効果は発現されず，１．５％を超えて添加すると粒界強度を低下させ靱性が劣化するので，最適添加範囲を０．１％〜１．５％とした。
【００１２】
Ｐ：Ｐは粒界に偏析して粒界強度を低下させ、靱性を劣化させる不純物元素であり、可及的低レベルが望ましいが、現状精錬技術の到達可能レベルとコストを考慮して、上限を０．０２％とした。
【００１３】
Ｓ：Ｓは熱間加工性及び靭性を劣化させる不純物元素であり、可及的低レベルが望ましいが、現状精錬技術の到達可能レベルとコストを考慮して、上限を０．０１％とした。
【００１４】
Ｃｒ：Ｃｒは耐食性向上の基本元素であり、十分な耐食性を得るには１２％以上の添加が必要であるが、フェライト安定化元素でもあり、多すぎると熱間加工時にδフェライトが析出して熱間加工性を劣化するため、上限を１４％とした。
【００１５】
Ｎｉ：Ｎｉはオーステナイト安定化元素であり、圧延疵につながるδフェライトの生成を抑止するとともに、マルテンサイト母相中に残留オーステナイトを微細分散させ靭性を向上させるのに有効であるが、１％未満ではその効果は発現されず、３％を超えて添加するとＡｃ 1 点が低下し強度調質可能範囲が制限されることから，最適添加量を１％〜３％とした。
【００１６】
Ａｌ：Ａｌは製鋼工程において脱酸及び脱硫を促進させるために添加される。０．３％を超えて含有されると靭性が劣化することから、上限を０．３％とした。
【００１７】
Ｎ：Ｎは窒化物を形成し結晶粒粗大化を抑制する効果があるが，０．００１％未満ではその効果は発現されず、０．０８％を超えて添加すると靭性が劣化するため，最適添加量を０．００１％〜０．０８％とした。
【００１８】
Ｍｏ：ＭｏはＰの粒界偏析を抑制し靭性向上に有効な元素であり，必要に応じて添加するが、フェライト安定化元素でもあり、多すぎると熱間加工時にδフェライトが析出して熱間加工性を劣化するため、上限を０．５％とした。
【００１９】
Ｃｕ：ＣｕはＮｉと同様に耐腐食性向上に有効な元素であるとともに、オーステナイト安定化元素でありδフェライトの生成を抑止し圧延疵防止に有効であるため，必要に応じて添加するが、１．５％を越えて添加すると粒界に過剰に偏析して粒界強度を低下させるため熱間加工性が著しく劣化するため、上限を１．５％とした。
【００２０】
Ｔｉ：ＴｉはＳによる熱間加工性劣化を抑制するものであり、必要に応じて添加するが、０．００１％未満ではその効果が発現されず、０．０５％を超えて添加してもその効果は飽和し，逆に粗大な窒化物を析出して靭性を低下させるため、最適添加量を０．００１％〜０．０５％とした。
【００２１】
Ｃａ：ＣａはＳによる熱間加工性劣化を抑制するものであり、必要に応じて添加するが、０．００１％未満ではその効果が発現されず、０．０１％を越えて添加するとＣａ系介在物が増加して耐硫化物応力割れ性が劣化するので、最適添加量を０．００１％〜０．０１％とした。
【００２２】
本発明鋼は、主にマンネスマン方式の熱間圧延法によって継目無管に造管される。ここでいうマンネスマン方式の圧延法とは矩形断面もしくは丸断面の管材を用い、プレスロース穿孔法あるいはマンネスマン穿孔法により穿孔した後、必要に応じて傾斜圧延機（エロンゲータ）により延伸し、さらにプラグミルあるいはマンドレルミルにより造管していくプロセスを意味する。
【００２３】
【実施例】
表１に示す成分の外径１７７．８ｍｍ，肉厚１１．５ｍｍの熱間圧延ままの鋼管に表１に示す条件で熱処理を施して６５０ＭＰａを超える高強度に調質し、Ｖノッチシャルピー衝撃試験（JIS Z 2242，フルサイズ，Ｌ方向）を行い破面遷移温度を求めた。また、降伏応力を引張試験（JIS Z 2241）により求めた。結果を表１に示す。表１において２相域処理とはＡｃ 1 点以上Ａｃ 3点以下の温度に加熱し続いて室温まで冷却する熱処理を意味する。
【００２４】
本発明（Ｎｏ．１〜Ｎｏ．１０）によれば降伏応力が６５０ＭＰａを超える高強度を有しかつ破面遷移温度が−３０℃以下の良好な低温靭性が得られることが明らかである。特に、Ａｃ 1 点以上Ａｃ 3点以下の２相域温度に加熱する熱処理を行う前に、Ａｃ 3点以上９５０℃以下の温度域に加熱し続いて室温まで空冷以上の速度で冷却する熱処理を行うと、いっそう優れた低温靭性が得られることが明らかである（本発明Ｎｏ．９，１０）。一方、比較例（Ｎｏ．１１〜Ｎｏ．１８）ではいずれも破面遷移温度が０℃以上であり良好な低温靭性は得られていない。
【００２５】
【表１】
【発明の効果】
以上のように本発明によれば，降伏応力が６５０ＭＰａを超える高強度を有しかつ優れた低温靭性を有するマルテンサイト系ステンレス鋼管の製造方法を提供する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing martensitic stainless steel having excellent low temperature toughness.
[0002]
[Prior art]
Martensitic stainless steel has been applied as an oil well pipe since about 1980 because it is excellent in strength and CO 2 corrosion resistance and is relatively inexpensive, as represented by AISI 420 steel. Usually, after pipe making, it is manufactured by quenching and tempering, but its low-temperature toughness is insufficient, so its use in cold regions is limited. Therefore, as a production method for obtaining excellent low-temperature toughness, a production method for suppressing precipitation of coarse chromium carbide by increasing the cooling rate after austenitization as seen in JP-A-3-75308, etc. A production method that suppresses the precipitation of coarse chromium carbide by increasing the cooling rate after tempering, as seen in Kaihei 5-263134, etc., and at the time of austenitization as seen in JP-A-4-210453, etc. A manufacturing method in which the rate of temperature increase is increased and the holding time is shortened to prevent coarsening of the austenite grain size, as shown in JP-A-63-238217, JP-A-63-241117, etc. A manufacturing method using a heat treatment method has been proposed. However, even if these measures are taken, the present situation is that sufficient low-temperature toughness has not been obtained in high strength materials whose yield stress exceeds 650 MPa .
[0003]
[Problems to be solved by the invention]
The present invention is intended to solve the above-described problems, and provides a method for producing martensitic stainless steel having high strength with yield stress exceeding 650 MPa and excellent low-temperature toughness. For the purpose.
[0004]
[Means for Solving the Problems]
As a result of conducting various heat treatments on various materials having different components and researching low temperature toughness, the present inventors have found that C is 0.10% or more and 0.18% or less, Ni is 1% or more and 3%. After the 13% Cr steel prepared as described below is formed by hot rolling, it is heated to a temperature of Ac 1 point or more and Ac 3 point or less and then cooled to room temperature at a rate higher than air cooling. Austenite becomes a finely dispersed structure, and when this is tempered at a temperature of Ac 1 point or less, low-temperature toughness is greatly improved, and precipitation of δ ferrite that degrades hot workability is within the above component range. It was found that it can be prevented.
[0005]
The present invention is configured based on such knowledge, the gist of which is weight%,
C: 0.10 to 0.18%, Si: 0.5% or less,
Mn: 0.1 to 1.5% or less, P: 0.02% or less,
S: 0.01% or less, Cr: 12-14%,
Ni: 1-3%, Al: 0.3% or less,
N: 0.001 to 0.08%
And, if necessary,
Mo: 0.5% or less, Cu: 1.5% or less,
Ti: 0.001-0.05%, Ca: 0.001-0.01%
After forming a martensitic stainless steel containing one or more of the following, and the balance consisting of Fe and inevitable impurities by hot rolling, a temperature range of Ac 3 to 950 ° C as required And then cooled to room temperature at a rate of air cooling or more, heated to a temperature of Ac 1 point or more and Ac 3 point or less, and then cooled to room temperature at a rate of air cooling or more , and then at a temperature of Ac 1 point or less. A method for producing a martensitic stainless steel pipe excellent in low temperature toughness characterized by tempering.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail. When heated to a martensitic stainless steel of representative steels and is AISI420 steel (0.2% C-13% Cr ) a Ac 1 point or more Ac 3 point or less of the inverse temperature austenite is generated, followed by room temperature When cooled at a rate higher than air cooling, reversely transformed austenite is transformed into martensite, so that hardly any retained austenite is formed. However, when the amount of C is reduced to 0.18% or less and a steel having a component added with 1% or more of Ni, which is an austenite stabilizing element, is heated to a temperature of Ac 1 point or more and Ac 3 point or less, the steel is reversely transformed into the austenite phase. Since Ni is concentrated and the stability of austenite is increased, austenite is retained even when cooled to room temperature at a rate higher than air cooling. That is, it becomes a structure in which retained austenite is finely dispersed in the martensite matrix. When this is tempered at a temperature of Ac 1 point or less, the low temperature toughness is greatly improved. Although better Ni amount is large in order to improve the stability of the reverse transformed austenite, when too large, since Ac 1 point is restricted decreased strength tempering range, and 3% the upper limit of the Ni content did. In order to prevent martensite transformation at the temperature of Ac 1 point or more and Ac 3 point or less and reversely transformed martensite to cool to room temperature, the lower the amount of C , the better. In order to prevent the formation of δ ferrite which deteriorates, the lower limit was made 0.1%.
[0007]
After tube forming by hot rolling method, before performing heat treatment that is heated to a temperature of Ac 1 point or more and Ac 3 point or less and then cooled to room temperature at a rate higher than air cooling, a temperature range of Ac 3 point or more and 950 ° C. or less If heat treatment is subsequently performed followed by cooling to room temperature at a rate higher than air cooling, the low temperature toughness can be further improved. This is because the austenite grain growth is caused by grain boundary pinning of the insoluble carbide when it is formed in the hot rolling method and then heated to the coexisting temperature range of austenite and insoluble carbide and then cooled to room temperature at a rate higher than air cooling. This is because the austenite grain size can be reduced by the suppressing effect, and since precipitation of coarse chromium carbide at the grain boundaries can be suppressed by cooling at a rate higher than that of air cooling because there is less solid solution carbon.
[0008]
If necessary, heat to a temperature range of Ac 3 points or more and 950 ° C or less, then cool to room temperature at a rate of air cooling or higher, heat to temperatures of Ac 1 point or more and Ac 3 points or less, and then cool to room temperature or higher than air cooling rate The required strength and toughness can be obtained by tempering the two-phase mixed structure of martensite and retained austenite cooled at a temperature below Ac 1 point. However, when the tempering temperature exceeds Ac 1 point, the yield stress decreases rapidly. Therefore, strength cannot be built stably. Therefore, the tempering temperature was set to Ac 1 point or less.
[0009]
The reasons for limiting the components of the martensitic stainless steel pipe in the present invention are as follows.
C: When C exceeds 0.18%, deterioration of corrosion resistance and toughness occurs, so the upper limit was made 0.18%. On the other hand, if the content is less than 0.10%, δ ferrite precipitates in the hot working temperature range and deteriorates the hot workability.
[0010]
Si: Si is added as a deoxidizer in the steelmaking process. If the content exceeds 0.5%, the toughness deteriorates, so the upper limit was made 0.5%.
[0011]
Mn: Mn is an austenite stabilizing element, and is effective for preventing rolling flaws by suppressing precipitation of δ ferrite during hot working. However, if it is less than 0.1%, the effect is not manifested, and 1.5% If added beyond the range, the grain boundary strength is lowered and the toughness deteriorates, so the optimum addition range was set to 0.1% to 1.5%.
[0012]
P: P is an impurity element that segregates at the grain boundary to lower the grain boundary strength and deteriorates toughness, and is preferably as low as possible. However, the upper limit is considered in consideration of the reachable level and cost of current refining technology. Was 0.02%.
[0013]
S: S is an impurity element that deteriorates hot workability and toughness, and is preferably as low as possible. However, the upper limit is set to 0.01% in consideration of the reachable level and cost of the current refining technology.
[0014]
Cr: Cr is a basic element for improving corrosion resistance. To obtain sufficient corrosion resistance, addition of 12% or more is necessary, but it is also a ferrite stabilizing element. If it is too much, δ ferrite precipitates during hot working. In order to deteriorate hot workability, the upper limit was made 14%.
[0015]
Ni: Ni is an austenite stabilizing element, and is effective in suppressing the formation of δ ferrite leading to rolling defects and finely dispersing retained austenite in the martensite matrix to improve toughness, but less than 1% In this case, the effect is not manifested, and if the addition exceeds 3%, the Ac 1 point is lowered and the range in which the strength can be tempered is limited.
[0016]
Al: Al is added to promote deoxidation and desulfurization in the steel making process. If the content exceeds 0.3%, the toughness deteriorates, so the upper limit was made 0.3%.
[0017]
N: N has the effect of suppressing the formation of nitrides by forming nitrides, but if less than 0.001%, the effect is not manifested, and if added over 0.08%, the toughness deteriorates. The addition amount was set to 0.001% to 0.08%.
[0018]
Mo: Mo is an element that suppresses grain boundary segregation of P and is effective in improving toughness. It is added as necessary, but it is also a ferrite stabilizing element. If too much, δ ferrite precipitates during hot working and heat In order to deteriorate the inter-workability, the upper limit was made 0.5%.
[0019]
Cu: Cu is an element effective for improving the corrosion resistance like Ni, and is an austenite stabilizing element. It suppresses the formation of δ ferrite and is effective for preventing rolling flaws. If added over 1.5%, it segregates excessively at the grain boundary and lowers the grain boundary strength, so the hot workability is remarkably deteriorated, so the upper limit was made 1.5%.
[0020]
Ti: Ti suppresses hot workability deterioration due to S, and is added as necessary. However, if it is less than 0.001%, the effect is not exhibited, and even if it exceeds 0.05%, Ti is added. The effect is saturated, and on the contrary, coarse nitrides are precipitated to lower the toughness. Therefore, the optimum addition amount is set to 0.001% to 0.05%.
[0021]
Ca: Ca suppresses hot workability deterioration due to S, and is added as necessary. However, if less than 0.001%, the effect is not expressed, and if added over 0.01%, Ca type is added. Since the inclusions increase and the resistance to sulfide stress cracking deteriorates, the optimum addition amount is set to 0.001% to 0.01%.
[0022]
The steel of the present invention is formed into a seamless pipe mainly by a Mannesmann hot rolling method. The Mannesmann rolling method used here is a tube having a rectangular or round cross section, and after being drilled by the press-loose drilling method or the Mannesmann drilling method, it is stretched by an inclined rolling mill (an elongator) as necessary, and further, plug mill or It means the process of pipe making by mandrel mill.
[0023]
【Example】
A steel pipe as hot rolled with an outer diameter of 177.8 mm and a wall thickness of 11.5 mm having the components shown in Table 1 is heat treated under the conditions shown in Table 1 and tempered to a high strength exceeding 650 MPa , and a V-notch Charpy impact A test (JIS Z 2242, full size, L direction) was performed to determine the fracture surface transition temperature. Further, the yield stress was determined by a tensile test (JIS Z 2241). The results are shown in Table 1. In Table 1, the two-phase region treatment means a heat treatment in which heating is performed at a temperature not lower than Ac 1 point and not higher than Ac 3 point, and subsequently cooled to room temperature.
[0024]
According to the present invention (No. 1 to No. 10), it is clear that good low temperature toughness having a high strength with a yield stress exceeding 650 MPa and a fracture surface transition temperature of −30 ° C. or less can be obtained. In particular, before performing heat treatment to heat to a two-phase region temperature of Ac 1 point or more and Ac 3 point or less, heat treatment to a temperature region of Ac 3 point or more and 950 ° C. or less and then cooling to room temperature at a rate higher than air cooling is performed. It is apparent that even better low-temperature toughness can be obtained (Invention Nos. 9 and 10). On the other hand, in all the comparative examples (No. 11 to No. 18), the fracture surface transition temperature is 0 ° C. or higher, and good low temperature toughness is not obtained.
[0025]
[Table 1]
【The invention's effect】
As described above, according to the present invention, there is provided a method for producing a martensitic stainless steel pipe having a high strength with yield stress exceeding 650 MPa and excellent low temperature toughness.
Claims (4)
Ｃ ：０．１０〜０．１８％、
Ｓｉ：０．５％以下、
Ｍｎ：０．１〜１．５％、
Ｐ ：０．０２％以下、
Ｓ ：０．０１％以下、
Ｃｒ：１２〜１４％、
Ｎｉ：１〜３％、
Ａｌ：０．３％以下、
Ｎ ：０．００１〜０．０８％
を含有し、残部がＦｅ及び不可避的不純物からなるマルテンサイト系ステンレス鋼を熱間圧延法により造管した後、Ａｃ 1 点以上Ａｃ 3 点以下の温度に加熱し続いて室温まで空冷以上の速度で冷却し、しかる後、Ａｃ 1 点以下の温度で焼戻し処理することを特徴とする低温靭性に優れたマルテンサイト系ステンレス鋼管の製造方法。% By weight
C: 0.10 to 0.18%,
Si: 0.5% or less,
Mn: 0.1 to 1.5%
P: 0.02% or less,
S: 0.01% or less,
Cr: 12-14%,
Ni: 1-3%
Al: 0.3% or less,
N: 0.001 to 0.08%
After forming a martensitic stainless steel containing Fe and the inevitable impurities by hot rolling, the steel is heated to a temperature of Ac 1 point or more and Ac 3 point or less, and then cooled to room temperature at a rate higher than air cooling. A method for producing a martensitic stainless steel pipe excellent in low-temperature toughness, characterized by cooling at room temperature and then tempering at a temperature of Ac 1 point or less.
Ｃ ：０．１０〜０．１８％、
Ｓｉ：０．５％以下、
Ｍｎ：０．１〜１．５％、
Ｐ ：０．０２％以下、
Ｓ ：０．０１％以下、
Ｃｒ：１２〜１４％、
Ｎｉ：１〜３％、
Ａｌ：０．３％以下、
Ｎ ：０．００１〜０．０８％
を含有し、さらに、
Ｍｏ：０．５％以下、
Ｃｕ：１．５％以下、
Ｔｉ：０．００１〜０．０５％、
Ｃａ：０．００１〜０．０１％
の１種または２種以上を含有し、残部がＦｅ及び不可避的不純物からなるマルテンサイト系ステンレス鋼を熱間圧延法により造管した後、Ａｃ 1 点以上Ａｃ 3 点以下の温度に加熱し続いて室温まで空冷以上の速度で冷却し、しかる後、Ａｃ 1 点以下の温度で焼戻し処理することを特徴とする低温靭性に優れたマルテンサイト系ステンレス鋼管の製造方法。% By weight
C: 0.10 to 0.18%,
Si: 0.5% or less,
Mn: 0.1 to 1.5%
P: 0.02% or less,
S: 0.01% or less,
Cr: 12-14%,
Ni: 1-3%
Al: 0.3% or less,
N: 0.001 to 0.08%
In addition,
Mo: 0.5% or less,
Cu: 1.5% or less,
Ti: 0.001 to 0.05%,
Ca: 0.001 to 0.01%
After forming a martensitic stainless steel containing one or more of the following, with the balance consisting of Fe and unavoidable impurities by hot rolling, heating to a temperature of Ac 1 point or more and Ac 3 point or less A method for producing a martensitic stainless steel pipe excellent in low-temperature toughness, characterized by cooling to room temperature at a rate higher than air cooling and then tempering at a temperature of Ac 1 point or less.
Ｃ ：０．１０〜０．１８％、
Ｓｉ：０．５以％下、
Ｍｎ：０．１〜１．５％以下、
Ｐ ：０．０２％以下、
Ｓ ：０．０１％以下、
Ｃｒ：１２〜１４％、
Ｎｉ：１〜３％、
Ａｌ：０．３％以下、
Ｎ ：０．００１〜０．０８％
を含有し、残部がＦｅ及び不可避的不純物からなるマルテンサイト系ステンレス鋼を熱間圧延法により造管した後、Ａｃ 3 点以上９５０℃以下の温度域に加熱し続いて室温まで空冷以上の速度で冷却し、Ａｃ 1 点以上Ａｃ 3 点以下の温度に加熱し続いて室温まで空冷以上 の速度で冷却し、しかる後、Ａｃ 1点以下の温度で焼戻し処理することを特徴とする低温靭性に優れたマルテンサイト系ステンレス鋼管の製造方法。% By weight
C: 0.10 to 0.18%,
Si: 0.5% or less,
Mn: 0.1 to 1.5% or less,
P: 0.02% or less,
S: 0.01% or less,
Cr: 12-14%,
Ni: 1-3%
Al: 0.3% or less,
N: 0.001 to 0.08%
After forming a martensitic stainless steel containing Fe and the inevitable impurities by hot rolling, the steel is heated to a temperature range of Ac 3 to 950 ° C. and then cooled to room temperature at a rate higher than air cooling. To low temperature toughness, characterized by heating to a temperature of Ac 1 point or more and Ac 3 point or less, followed by cooling to room temperature at a rate of air cooling or more , and then tempering at a temperature of Ac 1 point or less. An excellent method for producing martensitic stainless steel pipes.
Ｃ ：０．１０〜０．１８％、
Ｓｉ：０．５％以下、
Ｍｎ：０．１〜１．５％以下、
Ｐ ：０．０２％以下、
Ｓ ：０．０１％以下、
Ｃｒ：１２〜１４％、
Ｎｉ：１〜３％、
Ａｌ：０．３％以下、
Ｎ ：０．００１〜０．０８％
を含有し、さらに、
Ｍｏ：０．５％以下、
Ｃｕ：１．５％以下、
Ｔｉ：０．００１〜０．０５％、
Ｃａ：０．００１〜０．０１％
の１種または２種以上を含有し，残部がＦｅ及び不可避的不純物からなるマルテンサイト系ステンレス鋼を熱間圧延法により造管した後、Ａｃ 3 点以上９５０℃以下の温度域に加熱し続いて室温まで空冷以上の速度で冷却し、Ａｃ 1 点以上Ａｃ 3 点以下の温度に加熱し続いて室温まで空冷以上の速度で冷却し、しかる後、Ａｃ 1 点以下の温度で焼戻し処理することを特徴とする低温靭性に優れたマルテンサイト系ステンレス鋼管の製造方法。% By weight
C: 0.10 to 0.18%,
Si: 0.5% or less,
Mn: 0.1 to 1.5% or less,
P: 0.02% or less,
S: 0.01% or less,
Cr: 12-14%,
Ni: 1-3%
Al: 0.3% or less,
N: 0.001 to 0.08%
In addition,
Mo: 0.5% or less,
Cu: 1.5% or less,
Ti: 0.001 to 0.05%,
Ca: 0.001 to 0.01%
After forming a martensitic stainless steel containing one or more of the following, with the balance consisting of Fe and inevitable impurities by hot rolling, it is heated to a temperature range of Ac 3 to 950 ° C. Cooling to room temperature at a rate higher than air cooling, heating to a temperature of Ac 1 point or more and Ac 3 points or less, then cooling to room temperature at a rate higher than air cooling, and then tempering at a temperature of Ac 1 point or less. A method for producing a martensitic stainless steel pipe excellent in low temperature toughness characterized by
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|---|---|---|---|
| JP12065098A JP3921809B2 (en) | 1998-04-30 | 1998-04-30 | Method for producing martensitic stainless steel pipe with excellent low temperature toughness |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12065098A JP3921809B2 (en) | 1998-04-30 | 1998-04-30 | Method for producing martensitic stainless steel pipe with excellent low temperature toughness |
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| Publication Number | Publication Date |
|---|---|
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| JP3921809B2 true JP3921809B2 (en) | 2007-05-30 |
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| JP4144283B2 (en) * | 2001-10-18 | 2008-09-03 | 住友金属工業株式会社 | Martensitic stainless steel |
| JP2003129190A (en) * | 2001-10-19 | 2003-05-08 | Sumitomo Metal Ind Ltd | Martensitic stainless steel and manufacturing method therefor |
| KR100545093B1 (en) * | 2001-11-05 | 2006-01-24 | 주식회사 포스코 | method of manufacturing a 12Cr hot rolled stainless steel |
| JP4952708B2 (en) * | 2008-12-19 | 2012-06-13 | 住友金属工業株式会社 | Martensitic stainless steel and method for producing the same |
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| CN102605258A (en) * | 2011-01-25 | 2012-07-25 | 宝山钢铁股份有限公司 | Martensitic stainless steel and manufacturing method thereof |
| CN102605258B (en) * | 2011-01-25 | 2014-05-07 | 宝山钢铁股份有限公司 | Martensitic stainless steel and manufacturing method thereof |
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