JPS61104056A - High-strength and high-toughness low-carbon cr-mo steel plate having excellent creep-resisting property as well as superior resistance to weld crack and erosion - Google Patents
High-strength and high-toughness low-carbon cr-mo steel plate having excellent creep-resisting property as well as superior resistance to weld crack and erosionInfo
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- JPS61104056A JPS61104056A JP22528084A JP22528084A JPS61104056A JP S61104056 A JPS61104056 A JP S61104056A JP 22528084 A JP22528084 A JP 22528084A JP 22528084 A JP22528084 A JP 22528084A JP S61104056 A JPS61104056 A JP S61104056A
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Abstract
Description
【発明の詳細な説明】
本発明は、主としてボイラ、圧力容器用として使用され
るＣ ｒ −Ｍ ｏ鋼に関し、詳しくは、耐エロージヨ
ン性及び耐クリープ特性にもすぐれる高・強度高靭性低
炭素Ｃｒ−Ｍｏ鋼板に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Cr-Mo steel mainly used for boilers and pressure vessels, and more specifically, it is a high-strength, high-toughness, low-carbon steel with excellent erosion resistance and creep resistance. This invention relates to a Cr-Mo steel plate.
従来より、１％Ｃｒ −０，５％Ｍｏ鋼板や１．２５お
。、］。、５工。鋼板、よ、ゎ油精製を、よ。いよする
化学工業プラントや、発電プラントにおける中・高温圧
力容器鋼板として広く用いられている。Conventionally, we have used 1%Cr-0.5%Mo steel sheets and 1.25%. , ]. , 5th construction. Steel plates, yo, oil refining, yo. It is widely used as medium- and high-temperature pressure vessel steel plates in industrial chemical plants and power plants.
しかし、これらの従来のＣｒ−Ｍｏ鋼板は、通常、Ｃ含
有量が０．１５％程度と高く、且つ、Ｃｒ、ＭＯ等の合
金成分を多量に含有しているために、溶接割れ感受性組
成ＰＣＩ’ｌが高く、その溶接施工にあたっては、低温
割れ防止のために、通常、１５０〜３５０℃程度での高
温の予熱を必要とし、製造期間の長期化や熱エネルギー
の大量消費等、製造コスト上昇の一因となっている。However, these conventional Cr-Mo steel sheets usually have a high C content of about 0.15% and contain large amounts of alloy components such as Cr and MO, so they have a weld cracking susceptibility composition PCI. 'l is high, and welding usually requires high-temperature preheating at about 150 to 350 degrees Celsius to prevent cold cracking, which increases manufacturing costs such as prolonging the manufacturing period and consuming a large amount of thermal energy. This is a contributing factor.
溶接性を改善するためには、ＰＣｏを低減すること、特
にＣ量を下げることが有効であることは既によく知られ
ている。しかし、ｃｌを低減すれば、強度の低下、耐エ
ロージヨン性の低下、高温クリ−１プ強度の低下等の問
題を生じるため、従来、低Ｃ化Ｃｒ−Ｍｏ鋼板は実用化
されていない。It is already well known that reducing PCo, particularly reducing the amount of C, is effective in improving weldability. However, reducing Cl causes problems such as a decrease in strength, a decrease in erosion resistance, and a decrease in high-temperature creep strength, so low-C Cr-Mo steel sheets have not been put to practical use so far.
一方、Ｂは、従来、焼入れ焼戻しを行なう調質鋼につい
ては広く利用されているが、一般に、焼ならし鋼乃至焼
ならし焼戻し鋼には、従来、殆ど添加されていな°いと
ころ、最近に至って、焼ならし鋼乃至焼ならし焼戻し鋼
にも微量のＢを添加することにより、鋼の焼入れ性の増
加を図り、強度を増加させる方法が実用化されるに至っ
ている。On the other hand, B has conventionally been widely used in tempered steel that undergoes quenching and tempering, but in general, it has rarely been added to normalized steel or normalized and tempered steel, but recently B As a result, a method has been put into practical use in which a small amount of B is added to normalized steel or even normalized and tempered steel to increase the hardenability and strength of the steel.
しかし、Ｃｒ−Ｍｏ鋼に関しては、従来、Ｂ添加は、耐
ＳＲ脆化特性の付与及び高強度高靭性化、熱間加工性の
改善等の目的に゛限られており、しかも、このようなＣ
ｒ−Ｍｏ鋼におけるＣ含有量は、従来鋼とほぼ同等であ
って、約０．１１％以上であるので、大幅な溶接性の改
善には至っていない。However, with regard to Cr-Mo steel, B addition has conventionally been limited to the purposes of imparting SR embrittlement resistance, increasing strength and toughness, and improving hot workability. C
The C content in r-Mo steel is approximately the same as that in conventional steel, and is about 0.11% or more, so weldability has not been significantly improved.
本発明者らは、Ｃｒ −Ｍ ｏ鋼における溶接性を改善
するために鋭意研究した結果、Ｃ量を著しく低減する一
方、適正量のＡｌ添加とＮ量の低減の下にＢを添加し、
更に、Ｃｕ及びＮｉを複合添加することにより、低Ｃ＠
でありながら、約０．１１〜０．２１％のようにＣ量の
多い従来のＣｒ−Ｍ。As a result of intensive research to improve the weldability of Cr-Mo steel, the present inventors have significantly reduced the amount of C while adding B while adding an appropriate amount of Al and reducing the amount of N.
Furthermore, by adding Cu and Ni in combination, low C@
However, conventional Cr-M has a large amount of C, about 0.11 to 0.21%.
鋼と比肩し得るすぐれた強度、靭性、耐エロージヨン性
、耐クリープ特性を有する新規なＣｒ−Ｍｏ鋼を得るこ
とができることを見出して、本発明に至ったものである
。The present invention was achieved by discovering that it is possible to obtain a new Cr-Mo steel that has excellent strength, toughness, erosion resistance, and creep resistance comparable to steel.
即ち、本発明は、耐溶接割れ性、耐エロージヨン性及び
耐クリープ特性にすぐれる高強度高靭性焼ならし焼戻し
型低炭素Ｃｒ−Ｍｏ鋼板を提供することを目的とする。That is, an object of the present invention is to provide a high-strength, high-toughness normalized and tempered low carbon Cr-Mo steel sheet that has excellent weld cracking resistance, erosion resistance, and creep resistance.
本発明によるかかるＣ ｒ −Ｍ ｏ 鋼の第１は、重
量％で
Ｃ０．０３〜０．１０％、
Ｓｉ０．０５〜１．００％、
Ｍｎ、０．３０〜０．９５％、
Ｐ ０．０２０％以下、
Ｓ ０．０１５％以下、
Ｃｕ ０．０５〜０．５０％、
Ｎｉ０．０５〜０．５０％、
Ｃｒ ０．４０〜１．７５％、
Ｍｏ ０．２０〜０．７５％、
Ｂ ０．０００３〜０．００２０％、ｓｏｌ Ａ１
０．００５〜０．１００％、Ｎ ０．００５％以下
、
残部鉄及び不可避的不純物よりなり、
で定義されるＰＣＭが０．２７％以下であり、且つ、そ
の主要組織がベイナイトであることを特徴とする。The first of such C r -Mo steels according to the invention have the following compositions in weight percent: C 0.03-0.10%, Si 0.05-1.00%, Mn, 0.30-0.95%, P 0. 020% or less, S 0.015% or less, Cu 0.05-0.50%, Ni 0.05-0.50%, Cr 0.40-1.75%, Mo 0.20-0.75%, B 0.0003-0.0020%, sol A1
0.005 to 0.100%, N 0.005% or less, balance iron and unavoidable impurities, PCM defined as 0.27% or less, and the main structure is bainite. Features.
また、本発明による第２のＣｒ−Ｍｏ鋼は、上記した化
学成分に加えて、
Ｎｂ ０．００５〜０．０７％、
−Ｖ ０．００５〜０．０７％、及びＣａ ０．
０００５〜０．００７０％よりなる群から選ばれる少な
くとも１種以上を含有することを特徴とする。In addition to the above-mentioned chemical components, the second Cr-Mo steel according to the present invention contains 0.005 to 0.07% Nb, 0.005 to 0.07% -V, and 0.07% Ca.
It is characterized by containing at least one kind selected from the group consisting of 0005 to 0.0070%.
以下に本発明について詳細に説明する。The present invention will be explained in detail below.
本発明によるＣｒ−Ｍｏ鋼において、Ｂは、オーステナ
イト中に固溶し、結晶粒界に偏析して、フェライト変態
を抑制するため、鋼の焼入れ性を向上させる。しかし、
他方において、Ｂは、鋼中のＮと結合しやすい。従って
、ＢがＢＮを生成すると、鋼中におけるＢの有効量が減
少し、焼入れ性を低下させる。従って、本発明において
は、鋼の焼入れ性を向上させるべく、Ｂの有効量を確保
するために、鋼中のＮ量を低減すると共に、ＡＮによっ
てＮを固定する。しかし、Ｂを過多に添加するときは、
オーステナイト粒界にＢ化合物が析出し、却って焼入れ
性を低下させるので、本発明においては、Ｂを適正量を
添加することが必要である。In the Cr-Mo steel according to the present invention, B dissolves in solid solution in austenite, segregates at grain boundaries, and suppresses ferrite transformation, thereby improving the hardenability of the steel. but,
On the other hand, B easily combines with N in steel. Therefore, when B forms BN, the effective amount of B in the steel decreases, reducing the hardenability. Therefore, in the present invention, in order to improve the hardenability of the steel and ensure an effective amount of B, the amount of N in the steel is reduced and N is fixed by AN. However, when adding too much B,
In the present invention, it is necessary to add an appropriate amount of B, since the B compound precipitates at the austenite grain boundaries and actually reduces the hardenability.
しかし、本発明鋼のように、低Ｃ鋼においては、Ｂの焼
入れ性向上効果を利用するだけでは、強度、靭性ほか目
的とする望ましい特性を得ることは困難である。ここに
おいて、本発明者らは、研究を重ねた結果、低Ｃ鋼にお
いて、Ｂを適正量添加して、その焼入性効果を利用する
と共に、Ｃｕ及びＮｉを複合添加することにより、鋼の
焼入れ性を 。However, in a low C steel like the steel of the present invention, it is difficult to obtain desired properties such as strength and toughness just by utilizing the hardenability improving effect of B. Here, as a result of repeated research, the present inventors have found that in low C steel, by adding an appropriate amount of B to utilize its hardenability effect, and by adding Cu and Ni in combination, the steel can be improved. Hardenability.
一層向上させると同時に、Ｂの焼入れ性向上効果との相
乗効果によって、鋼の主要組織をヘイナイトとし、かく
して、強度を上昇させ得ると同時に、耐エロージヨン性
及び耐クリープ特性をも従来鋼と同等以上に改善できる
ことを見出したのである。At the same time, due to the synergistic effect with the hardenability improvement effect of B, the main structure of the steel becomes haynite, thus increasing the strength, and at the same time, the erosion resistance and creep resistance properties are also higher than those of conventional steel. They found that improvements could be made.
次に、本発明によるＣｒ−Ｍｏ鋼における化学成分の限
定理由について説明する。Next, the reason for limiting the chemical composition of the Cr-Mo steel according to the present invention will be explained.
Ｃは、鋼の強度及び耐エロージヨン性を確保するために
、本発明鋼においては、０．０３％以上を添加すること
が必要であるが、反面、ｃｌの増加と共に溶接性、靭性
が低下するので、添加量の上限は０．１０％とする。In order to ensure the strength and erosion resistance of the steel, it is necessary to add 0.03% or more of C to the steel of the present invention, but on the other hand, weldability and toughness decrease as Cl increases. Therefore, the upper limit of the amount added is 0.10%.
Ｓｉは、強度の確保及び耐酸化性の向上のために有効で
あり、０．０５％以上を含有させるが、しかし、過多に
含有させるときは、焼戻し脆化感受性を高めるので、含
有量の上限は１．００％とする。Si is effective for securing strength and improving oxidation resistance, and is contained in an amount of 0.05% or more. However, when it is contained in an excessive amount, it increases the susceptibility to tempering embrittlement, so the upper limit of the content is shall be 1.00%.
Ｍｎは、鋼の強度と延性を高めるのに有効であるが、過
多に添加すると、溶接性が低下するので、添加量は０．
３０％〜０．９５％の範囲とする。Mn is effective in increasing the strength and ductility of steel, but if added in excess, weldability decreases, so the amount added is 0.
The range is 30% to 0.95%.
′ Ｐは、鋼中に不純物として含有されるが、靭性及び
溶接性を損なうばかりでなく、焼戻し脆化感受性を高め
るため、極力低減することが望ましい。'P is contained as an impurity in steel, but it not only impairs toughness and weldability, but also increases susceptibility to temper embrittlement, so it is desirable to reduce it as much as possible.
従って、本発明においては、Ｐの含有量は０．０２０％
以下とする。Therefore, in the present invention, the P content is 0.020%
The following shall apply.
Ｓも鋼中に不純物として含有されるが、鋼の靭 〜
性を著しく損なうので、極力低減することが望ましく、
含有量は０．０１５％以下とする。S is also contained as an impurity in steel, but the toughness of steel
It is desirable to reduce it as much as possible as it significantly impairs the
The content shall be 0.015% or less.
Ｃｕは、固溶強化及び析出強化に有効な成分であり、且
つ、耐エロージヨン性の向上にも効果がある。かかる効
果を有効に発揮させるためには、少なくとも０．０５％
を添加する必要がある。一方、０．５０％を越えて過多
に添加すると、熱間加工性が劣化するので、Ｃｕの添加
量は０．０５〜０．５０％の範囲とする。Cu is an effective component for solid solution strengthening and precipitation strengthening, and is also effective for improving erosion resistance. In order to effectively exhibit this effect, at least 0.05%
need to be added. On the other hand, if added in excess of 0.50%, hot workability deteriorates, so the amount of Cu added is in the range of 0.05 to 0.50%.
Ｎｉは、鋼の焼入れ性を増し、また、耐エロージヨン性
の向上に効果があり、更に、高温におけるオーステナイ
ト粒界へのＣｕの析出による亀甲割れを防止するのに有
効である。かがる効果を有効に発現させるためには、０
．０５％以上を添加する必要があるが、しかし、高価な
元素であるので、実用的な観点からその添加量は０．０
５〜０．５０％の範囲とする。Ni is effective in increasing the hardenability of steel and improving erosion resistance, and is also effective in preventing hexagonal cracking due to precipitation of Cu at austenite grain boundaries at high temperatures. In order to effectively express the darning effect, 0
．． It is necessary to add more than 0.05%, but since it is an expensive element, from a practical point of view, the amount added is less than 0.05%.
The range is 5% to 0.50%.
Ｃｒは、高温における耐食性と強度を確保するのに有効
であるので、少なくとも０．４０％を添加する。しかし
、過度に添加すると溶接性が劣化するので、その添加量
の上°限は１．７５％とする。Since Cr is effective in ensuring corrosion resistance and strength at high temperatures, at least 0.40% is added. However, if excessively added, weldability deteriorates, so the upper limit of the amount added is set at 1.75%.
ＭＯは、鋼の焼入れ性、特にＢと共存した場合の焼なら
し時の焼入れ性を高めるのに不可欠な元素である。また
、焼戻し軟化抵抗を高め、高温強度の向上にも有効であ
るので、０．２０％以上の添加を必要とするが、高価な
元素であるので、その添加量は０．２０〜０．７５％の
範囲とする。MO is an essential element for improving the hardenability of steel, especially when coexisting with B, the hardenability during normalizing. In addition, since it is effective in increasing temper softening resistance and improving high temperature strength, it is necessary to add 0.20% or more, but since it is an expensive element, the amount added is 0.20 to 0.75%. % range.
Ｂは、前記したように、焼ならし時の焼入れ性を高め、
強度上昇に有効であるので、本発明鋼においては、０．
０００３％以上を添加することが必要である。しかし、
０．００２０％を越えて過剰に添加するときは、焼なら
し時にＢ化合物を生成し、焼入れ性を低下させると同時
に靭性の劣化を伴う。As mentioned above, B increases the hardenability during normalizing,
Since it is effective in increasing the strength, in the steel of the present invention, 0.
It is necessary to add 0,003% or more. but,
When added in excess of more than 0.0020%, a B compound is generated during normalization, resulting in a decrease in hardenability and deterioration in toughness.
従って、添加量の上限は０．００２０％とする。Therefore, the upper limit of the amount added is 0.0020%.
５ｏｌＡ１は、前記したように、Ｎを固定し、また、組
織を微細化する作用があるが、その含有量がｏ、 ｏ
ｏ ｓ％よりも少ないときは、上記の効果が期待できず
、一方、含有量が０．１０％を越えると、鋼塊表面割れ
の原因となることから、その含有量は０．００５〜０．
１０％の範囲とする。As mentioned above, 5olA1 has the effect of fixing N and refining the structure, but when its content is o, o
If the content is less than 0.0s%, the above effects cannot be expected, and on the other hand, if the content exceeds 0.10%, it may cause surface cracking of the steel ingot, so the content should be 0.005 to 0. ．．
The range is 10%.
Ｎは、その含有量が０． ’００５％を越えるときは、
ＢＮを生成しやすくなり、その結果、焼入れ性に有効な
り量が減少し、鋼板の焼入れ性が低下するので、含有量
は０．００５％以下とする。N has a content of 0. When it exceeds '005%,
Since BN becomes easier to generate, and as a result, the amount effective for hardenability decreases, and the hardenability of the steel sheet deteriorates, the content is set to 0.005% or less.
前記ＦＦ ＣＭは、よく知られているように、溶接時の
低温割れ感受性を示す指標であり、溶接施工時の予熱温
度をより低くするためには、この値を極力低く抑える必
要がある。予熱温度を約１００ ’Ｃにしても割れを生
じないようにするため、本発明Ｃｒ −Ｍ ｏ鋼におい
ては、Ｐ６．４を０．２７％以下とする。更に、予熱温
度を約５０℃以下とするためには、ＰＣＭを０．２３％
以下とすることが好ましい。As is well known, the FF CM is an index indicating cold cracking susceptibility during welding, and in order to lower the preheating temperature during welding, it is necessary to keep this value as low as possible. In order to prevent cracks from occurring even when the preheating temperature is about 100'C, in the Cr-Mo steel of the present invention, P6.4 is set to 0.27% or less. Furthermore, in order to keep the preheating temperature below about 50°C, PCM should be added at 0.23%.
The following is preferable.
本発明によれば、第２の発明によるＣｒ−Ｍ。According to the invention, Cr-M according to the second invention.
鋼は、前記した元素に加えて、Ｎｂ、■及びＣａよりな
る群から選ばれる少なくとも１種以上の元素を含有する
。In addition to the above-described elements, the steel contains at least one element selected from the group consisting of Nb, (2), and Ca.
Ｎｂ、Ｖは共に、結晶粒を微細化して強度を向上させる
のに有効であるが、それぞれ０．００５％未満ではその
効果が期待できず、一方、それぞれ０．０７％を越える
ときは、靭性及び溶接性を劣化させるのみならず、経済
性の点からも好ましくない。従って、その添加量は、そ
れぞれｏ、 ｏ ｏ ｓ〜０．０７％の範囲とする。Both Nb and V are effective in refining crystal grains and improving strength, but if each is less than 0.005%, the effect cannot be expected, while if each exceeds 0.07%, the toughness This not only deteriorates weldability but also is unfavorable from an economic point of view. Therefore, the amounts added are in the range of o, o o s to 0.07%, respectively.
Ｃａは、靭性を改善し、溶接継手、ボンド部の靭性を向
上させ、更に、板厚方向の特性を改善する。かかる効果
を有効に発揮させるには、少なくとも０．０００５％を
添加することが必要である。Ca improves toughness, improves the toughness of welded joints and bond parts, and further improves properties in the thickness direction. In order to effectively exhibit this effect, it is necessary to add at least 0.0005%.
しかし、０．００７０％を越えて過多に添加するときは
、非金属介在物の量が増して、延性を低下させる。従っ
て、本発明鋼においては、その添加量をｏ、 ｏ ｏ
ｏ ｓ〜０．００７０％の範囲とする。However, when added in excess of 0.0070%, the amount of nonmetallic inclusions increases and ductility decreases. Therefore, in the steel of the present invention, the addition amount is o, o o
The range is from os to 0.0070%.
上記Ｎｂ、■及びＣａは必要に応じて適当に組み合わせ
て使用されるが、■を添加する場合も、ＰＧＭを０．２
７％以下に抑える必要がある。The above Nb, ■, and Ca are used in appropriate combinations as necessary, but when adding ■, PGM is added by 0.2
It is necessary to keep it below 7%.
本発明によるＣｒ−Ｍｏ鋼を製造するには、常法に従い
、本発明による化学成分を存する鋼片を熱間圧延し引続
いて熱処理を行なえばよい。しがしながら、かかる方法
による製造においても、操作的にＢの焼入れ性向上効果
を最大限に発揮させることが望ましい。即ち、ＮをＡ１
で固定する場合、厚板の製品圧延時、鋼片の加熱温度が
１１５０℃を越えると、Ａ６Ｎの固溶が促進され、固溶
Ｎが増加する。このとき、オーステナイト粒界にＢＮを
析出するので、次に実施する焼ならし処理時におけるＢ
の焼入れ性向上効果が完全に発揮されない。従って、Ｂ
の焼入性向上効果を最大限に活用するためには、鋼片の
加熱温度を１２００℃以下とすることが望ましい。In order to produce the Cr-Mo steel according to the present invention, a steel billet having the chemical composition according to the present invention may be hot rolled and subsequently heat treated according to a conventional method. However, even in the production by such a method, it is desirable to maximize the hardenability improvement effect of B. That is, N is A1
In the case of fixing at , if the heating temperature of the steel billet exceeds 1150° C. during rolling of a thick plate product, the solid solution of A6N is promoted and the solid solution N increases. At this time, BN is precipitated at the austenite grain boundaries, so the B
The effect of improving hardenability is not fully exhibited. Therefore, B
In order to make the most of the hardenability improvement effect, it is desirable that the heating temperature of the steel slab be 1200°C or less.
また、焼ならし時に加速冷却を実施するごとにより、本
発明鋼の特性は大きく改善される。Further, the properties of the steel of the present invention are greatly improved by performing accelerated cooling during normalization.
実施例
第１表に示す化学組成を有する本発明によるＣｒ−Ｍａ
ｉｌ （Ｈｖ＝１７６）及び従来鋼Ｃｒ−Ｍ ｏ鋼２
（Ｈｖ＝１７８） 、及び比較＠３（Ｈｖ＝１３６）の
それぞれの耐エロージヨン性を第１図に示す。従来鋼は
Ｃ量が高く、比較鋼は本発明鋼においてＣｕ及びＮｉを
除いた化学成分組成を有する。Example Cr-Ma according to the present invention having the chemical composition shown in Table 1
il (Hv=176) and conventional steel Cr-Mo steel 2
(Hv=178) and Comparison@3 (Hv=136), respectively, are shown in FIG. 1. The conventional steel has a high C content, and the comparative steel has the chemical composition of the steel of the present invention except for Cu and Ni.
耐エローシコン性は、それぞれ表面を研摩した直径１０
龍の試験片の中心部に高圧で１５０℃の水を流速５ｍ／
秒で５００時間衝突させた後、試験片の腐食減電量を測
定して、評価した。The resistance to erosion is determined by a diameter of 10 mm with a polished surface.
Water at a temperature of 150°C was flowed at a flow rate of 5 m/m under high pressure into the center of the dragon test piece.
After colliding for 500 hours in seconds, the amount of electrical loss due to corrosion of the test piece was measured and evaluated.
比較鋼は、従来鋼と比較して耐エロージヨン性は低下し
ているが、Ｃｕ及びＮｉを複合添加した本発明鋼は、従
来鋼よりすぐれた耐エロージヨン性を有している。これ
は、Ｃｕ及びＮｉの複合添加によって、鋼の耐食性自体
が向上していること、また、焼入れ性向上により全体の
硬度が上昇していること、並びに低Ｃ化により、炭化物
の析出が少なく、結晶粒界及び粒内の強度差が小さいた
めに、局部的な腐食が起こり難くなっていることによる
。The comparative steel has lower erosion resistance than the conventional steel, but the steel of the present invention with a composite addition of Cu and Ni has better erosion resistance than the conventional steel. This is because the corrosion resistance of the steel itself has improved due to the combined addition of Cu and Ni, the overall hardness has increased due to improved hardenability, and due to the lower carbon content, there is less precipitation of carbides. This is because the difference in strength between grain boundaries and within grains is small, making it difficult for local corrosion to occur.
第２図に本発明によるＣ ｒ −Ｍ ｏ鋼１及び従来の
Ｃｒ−Ｍｏ鋼の高温クリープ破断強度を示す。FIG. 2 shows the high temperature creep rupture strength of the Cr-Mo steel 1 according to the present invention and the conventional Cr-Mo steel.
横軸（Ｐ）はＬａｒｓｏｎ−Ｍｉ １ｌｅｒパラメータ
を示し、Ｔは試験温度（Ｋ） 、ｔは破断時間（ｈ）で
ある。The horizontal axis (P) shows the Larson-Miler parameters, T is the test temperature (K), and t is the rupture time (h).
本発明鋼の破断強度は、従来鋼のそれと比較して同等以
上である。これは、本発明鋼によれば、クリープ温度域
において、ボイド発生の核となる結晶粒界上の炭化物の
析出が少ないうえに、粒界と粒内の強度差が小さいため
、粒界に歪の集中が起こり難いことによるものである。The breaking strength of the steel of the present invention is equal to or higher than that of conventional steel. This is because, according to the steel of the present invention, in the creep temperature range, there is less precipitation of carbides on the grain boundaries, which become the core of void generation, and the difference in strength between the grain boundaries and the grain interior is small, so the grain boundaries are strained. This is due to the fact that it is difficult to concentrate.
次に、第１表に示す化学成分を有する本発明鋼Ａ−Ｇ及
び比較鋼Ｈ−Ｋからなる鋼板の熱処理条件１．その機械
的特性及び溶接性をそれぞれ示す。Next, heat treatment conditions 1 for steel plates made of the invention steels A-G and comparative steels H-K having the chemical components shown in Table 1. Its mechanical properties and weldability are shown respectively.
本発明鋼は、比較鋼に比べてＣ量を大幅に低減している
ために、ＰＣＭが０．２７％以下であって、比較鋼より
低い。そのために、本発明鋼の斜めＹ形溶接割れ試験に
おけるルート割れ防止予熱温度は、比較鋼の場合、１０
０℃以上であるのに対して、本発明鋼によれば１００℃
以下である。また、同時に、本発明鋼の０℃における吸
収エネルギーｖＥｏは、比較鋼が１０．Ｏｋｇｆ−ｍで
あるのに対して、本発明鋼によれば、ｌ０．Ｏｋｇｆ−
ｍ以上である。更に、破面遷移温度ｖＴｒｓも、比較鋼
はＯに
℃以上であるが、本発明鋼によれば０℃以下である。こ
のように、本発明鋼は、耐溶接割れ性、耐エロージヨン
性及び耐クリープ特性にすぐれ且つ、高強度高靭性を有
している。Since the steel of the present invention has a significantly reduced C content compared to the comparative steel, the PCM is 0.27% or less, which is lower than the comparative steel. Therefore, the preheating temperature for preventing root cracking in the diagonal Y-shaped weld cracking test for the steel of the present invention is 10
0°C or higher, whereas according to the steel of the present invention, the temperature is 100°C
It is as follows. At the same time, the absorbed energy vEo at 0°C of the steel of the present invention is 10. Okgf-m, whereas according to the steel of the present invention, l0. Okgf-
m or more. Further, the fracture surface transition temperature vTrs is also 0°C or higher in the comparative steel, but is 0°C or lower in the steel of the present invention. As described above, the steel of the present invention has excellent weld cracking resistance, erosion resistance, and creep resistance, and has high strength and high toughness.
第１図は本発明鋼、比較鋼及び従来鋼の耐エロージヨン
性を示すグラフ、第２図は本発明鋼及び従来鋼のクリー
プ破断強度を示すグラフである。
３Ｃ
第１図
手続補正書（自発）
昭和５９年１１月２４日FIG. 1 is a graph showing the erosion resistance of the inventive steel, comparative steel, and conventional steel, and FIG. 2 is a graph showing the creep rupture strength of the inventive steel and the conventional steel. 3C Figure 1 procedural amendment (voluntary) November 24, 1982
Claims (2)
Ｃｒ）／（２０）＋（Ｎｉ）／（６０）で定義されるＰ
＿Ｃ＿Ｍが０．２７％以下であり、且つ、その主要組織
がベイナイトであることを特徴とする耐溶接割れ性、耐
エロージョン性及び耐クリープ特性にすぐれる高強度高
靭性焼ならし焼戻し型低炭素Ｃｒ−Ｍｏ鋼板。(1) C0.03-0.10% by weight, Si0.05-1.00%, Mn0.30-0.95%, P0.020% or less, S0.015% or less, Cu0.05-0 .50%, Ni0.05-0.50%, Cr0.40-1.75%, Mo0.20-0.75%, B0.0003-0.0020%, solAl0.005-0.100%, N0 .005% or less, the balance consists of iron and unavoidable impurities, P_C_M=C+(Si)/(30)+(Mn+Cu+
P defined as Cr)/(20)+(Ni)/(60)
A high-strength, high-toughness, normalized and tempered low carbon steel with excellent weld cracking resistance, erosion resistance, and creep resistance, characterized in that _C_M is 0.27% or less and its main structure is bainite. Cr-Mo steel plate.
鉄及び不可避的不純物よりなり、 Ｐ＿Ｃ＿Ｍ＝Ｃ＋（Ｓｉ）／（３０）＋（Ｍｎ＋Ｃｕ＋
Ｃｒ）／（２０）＋（Ｎｉ）／（６０）＋（Ｍｏ）／（
１５）＋（Ｖ）／（１０）＋５Ｂ（％）で定義されるＰ
＿Ｃ＿Ｍが０．２７％以下であり、且つ、その主要組織
がベイナイトであることを特徴とする耐溶接割れ性、耐
エロージョン性及び耐クリープ特性にすぐれる高強度高
靭性焼ならし焼戻し型低炭素Ｃｒ−Ｍｏ鋼板。(2) In weight% (a) C0.03-0.10%, Si0.05-1.00%, Mn0.30-0.95%, P0.020% or less, S0.015% or less, Cu0. 05~0.50%, Ni0.05~0.50%, Cr0.40~1.75%, Mo0.20~0.75%, B0.0003~0.0020%, solAl0.005~0.100 %, N0.005%, and (b) at least one member selected from the group consisting of Nb0.005-0.07%, V0.005-0.07%, and Ca0.0005-0.0070%. Above, and the balance consists of iron and unavoidable impurities, P_C_M=C+(Si)/(30)+(Mn+Cu+
Cr)/(20)+(Ni)/(60)+(Mo)/(
P defined as 15)+(V)/(10)+5B(%)
A high-strength, high-toughness, normalized and tempered low carbon steel with excellent weld cracking resistance, erosion resistance, and creep resistance, characterized in that _C_M is 0.27% or less and its main structure is bainite. Cr-Mo steel plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22528084A JPS61104056A (en) | 1984-10-25 | 1984-10-25 | High-strength and high-toughness low-carbon cr-mo steel plate having excellent creep-resisting property as well as superior resistance to weld crack and erosion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22528084A JPS61104056A (en) | 1984-10-25 | 1984-10-25 | High-strength and high-toughness low-carbon cr-mo steel plate having excellent creep-resisting property as well as superior resistance to weld crack and erosion |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61104056A true JPS61104056A (en) | 1986-05-22 |
| JPH0368100B2 JPH0368100B2 (en) | 1991-10-25 |
Family
ID=16826855
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22528084A Granted JPS61104056A (en) | 1984-10-25 | 1984-10-25 | High-strength and high-toughness low-carbon cr-mo steel plate having excellent creep-resisting property as well as superior resistance to weld crack and erosion |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61104056A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61186453A (en) * | 1985-02-13 | 1986-08-20 | Kobe Steel Ltd | High strength and high toughness quenched and tempered low-carbon steel plate for boiler or pressure vessel having superior resistance to weld crack, erosion and creep |
| JPS62146247A (en) * | 1985-12-20 | 1987-06-30 | Kobe Steel Ltd | Cr-mo steel plate for multilayer vessel |
| JPH01316419A (en) * | 1988-06-14 | 1989-12-21 | Nippon Steel Corp | Production of pressure-vessel steel with no need for heat treatment after welding |
| JPH02254133A (en) * | 1989-03-28 | 1990-10-12 | Sumitomo Metal Ind Ltd | Steel material for steel-frame construction having little lowering of elastic modulus at high temperature and its manufacture |
-
1984
- 1984-10-25 JP JP22528084A patent/JPS61104056A/en active Granted
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61186453A (en) * | 1985-02-13 | 1986-08-20 | Kobe Steel Ltd | High strength and high toughness quenched and tempered low-carbon steel plate for boiler or pressure vessel having superior resistance to weld crack, erosion and creep |
| JPS62146247A (en) * | 1985-12-20 | 1987-06-30 | Kobe Steel Ltd | Cr-mo steel plate for multilayer vessel |
| JPH01316419A (en) * | 1988-06-14 | 1989-12-21 | Nippon Steel Corp | Production of pressure-vessel steel with no need for heat treatment after welding |
| JPH0635618B2 (en) * | 1988-06-14 | 1994-05-11 | 新日本製鐵株式会社 | Method for manufacturing pressure vessel steel that does not require heat treatment after welding |
| JPH02254133A (en) * | 1989-03-28 | 1990-10-12 | Sumitomo Metal Ind Ltd | Steel material for steel-frame construction having little lowering of elastic modulus at high temperature and its manufacture |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0368100B2 (en) | 1991-10-25 |
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