JPH04183842A - Low-carbon cr-mo steel sheet excellent in strength at high temperature and welding cracking resistance - Google Patents
Low-carbon cr-mo steel sheet excellent in strength at high temperature and welding cracking resistanceInfo
- Publication number
- JPH04183842A JPH04183842A JP31192690A JP31192690A JPH04183842A JP H04183842 A JPH04183842 A JP H04183842A JP 31192690 A JP31192690 A JP 31192690A JP 31192690 A JP31192690 A JP 31192690A JP H04183842 A JPH04183842 A JP H04183842A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- strength
- cracking resistance
- cracking
- steel sheet
- 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.)
- Granted
Links
- 238000005336 cracking Methods 0.000 title claims abstract description 53
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 51
- 239000010959 steel Substances 0.000 title claims abstract description 51
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 15
- 238000003466 welding Methods 0.000 title abstract description 6
- 229910052796 boron Inorganic materials 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 229910052802 copper Inorganic materials 0.000 claims abstract description 5
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 4
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 4
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 3
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 3
- 229910052804 chromium Inorganic materials 0.000 claims abstract 2
- 229910052760 oxygen Inorganic materials 0.000 claims abstract 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 12
- 238000000034 method Methods 0.000 abstract description 2
- 229910052758 niobium Inorganic materials 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 14
- 239000006104 solid solution Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 6
- 238000001556 precipitation Methods 0.000 description 4
- 238000005728 strengthening Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000003628 erosive effect Effects 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 239000010953 base metal Substances 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 150000003568 thioethers Chemical class 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、高温強度が高く、かつ、耐溶接割れ性に優れ
る低炭素Ｃｒ −Ｍｏ鋼板に関し、詳しくは、３００〜
５００°Ｃで高い引張強さを有するとともに、溶接時に
生じる低温割れおよびその後の応力除去焼鈍（以下、Ｓ
Ｒという）中に生じるＳＲ割れを防止した高温強度およ
び耐溶接割れ性に優れる低炭素Ｃｒ−Ｍｏ鋼板に関する
ものである。Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a low carbon Cr-Mo steel plate having high high temperature strength and excellent weld cracking resistance.
It has high tensile strength at 500°C, and is resistant to low-temperature cracking that occurs during welding and subsequent stress relief annealing (hereinafter referred to as S
The present invention relates to a low carbon Cr-Mo steel sheet that prevents SR cracking occurring in the steel (referred to as R) and has excellent high-temperature strength and weld cracking resistance.
（従来の技術）
従来から、Ｃｒ −Ｍｏ鋼板は、石油精製をはじめとす
る化学工業プラントや、発電プラントにおける中、高温
圧力容器や、タービンダイヤフラム材等の発電タービン
の構造部材として広く用いられている。(Prior art) Cr-Mo steel sheets have been widely used as structural members of power generation turbines, such as medium and high temperature pressure vessels in chemical industry plants such as oil refining, power generation plants, and turbine diaphragm materials. There is.
しかし、従来のＣｒ−Ｍｏ鋼板は、通常Ｃ含有量か０．
１５％程度と高いため、溶接割れ感受性か高く、低温割
れ防止のために、通常、１５０〜３５０ ’Ｃ程度の予
熱を必要とし、製造期間の長期化や熱エネルギの大量消
費等、製造コスト上昇の一因となっていた。However, conventional Cr-Mo steel sheets usually have a C content of 0.
As it is about 15% high, it is highly susceptible to weld cracking, and in order to prevent low temperature cracking, preheating of about 150 to 350'C is usually required, which increases production costs such as prolonging the production period and consuming a large amount of thermal energy. This was a contributing factor.
そこで、本発明者らは、Ｃｒ −Ｍｏ鋼板における耐低
温割れ性を改善するために、既に、特Ｕｎ平２−６１０
３５号公報に記載されているように、Ｃ量を著しく低減
する一方、微量ＢおよびＣｕ、 Ｎｉを複合添加するこ
とによって、低炭素鋼でありなからＣＭｃの多い従来の
Ｃｒ−Ｍｏ鋼板と同等の特性を存するＣｒ −Ｍｏ鋼板
を得ることかできることを見出している。Therefore, in order to improve the cold cracking resistance of Cr-Mo steel sheets, the present inventors have already developed
As described in Publication No. 35, by significantly reducing the amount of C and adding trace amounts of B, Cu, and Ni in combination, it is a low carbon steel that is equivalent to conventional Cr-Mo steel sheets with a high CMc content. It has been discovered that it is possible to obtain a Cr-Mo steel sheet having the following characteristics.
さらに、Ｂの焼入れ性向上効果を有効に活用するため、
ＴｉでＮを固定し、鋼中のＳｏｌ、Ａｌ量を０．００５
％未満とすることによって、ＳＲ割れ感受性を従来鋼板
と同等な水準に抑える点も見い出している。Furthermore, in order to effectively utilize the hardenability improvement effect of B,
Fix N with Ti and reduce the amount of Sol and Al in the steel to 0.005
It has also been found that by setting the SR cracking sensitivity to less than %, the SR cracking susceptibility can be suppressed to the same level as conventional steel sheets.
（発明か解決しようとする課題）
しかしながら、最近は、これらＣｒ−Ｍｏ鋼板か使用さ
れるプラントにおいても、効率化のため操業条件を高温
、高圧化する傾向にあり、高温強度の優れたＣｒ−Ｍｏ
鋼板に対する要求は非常に強まっている。(Problem to be solved by the invention) However, recently, even in plants where these Cr-Mo steel plates are used, there is a trend to increase the operating conditions at high temperatures and pressures in order to improve efficiency. Mo
Demand for steel sheets has become extremely strong.
高温強度を高めるためには、析出強化型元素の添加か有
効て、特開昭５１−６９４２２号、特開昭６０−２３８
４５１号、特開昭６０−２３８４５２号公報には■およ
び／またはＮｂの添加か示されている。しかし、Ｖ、Ｎ
ｂは炭窒化物を形成し析出強化を呈するか故に、溶接性
や靭性を劣化させる。したかって、単にこれらの元素を
添加するだけでは溶接性、靭性に問題を生じる。特開昭
６０−２３８４５１号、特開昭６０−２３８４５２号公
報においては、Ｓｌの低減および固溶Ｓの低減により、
耐ＳＲ割れ特性、靭性は改善されているが、耐低温割れ
特性については触れられていない。In order to increase high-temperature strength, it is effective to add precipitation-strengthening elements.
No. 451 and Japanese Unexamined Patent Publication No. 60-238452 disclose the addition of (1) and/or Nb. However, V, N
Since b forms carbonitrides and exhibits precipitation strengthening, it deteriorates weldability and toughness. Therefore, simply adding these elements causes problems in weldability and toughness. In JP-A-60-238451 and JP-A-60-238452, by reducing Sl and solid solution S,
Although the SR cracking resistance and toughness have been improved, there is no mention of cold cracking resistance.
本発明は、上記の問題点を解決するためになされたもの
であり、■の添加により高温強度を確保し、Ｓｏｌ、Ａ
ｌ量の規制によりＳＲ割れを防止し、さらに、 Ｂを有
効に活用することにより母材強度および高温強度を確保
して、３００〜５００℃で高い引張強さを有するととも
に、溶接時に生じる低温割れおよびＳＲ割れを防止した
高温強度および耐溶接割れ性に優れる低炭素Ｃｒ−Ｍｏ
鋼板を提供することを目的とするものである。The present invention was made in order to solve the above problems, and it ensures high temperature strength by adding (2), and
By regulating the amount of B, SR cracking is prevented, and by effectively utilizing B, base metal strength and high temperature strength are ensured, and it has high tensile strength at 300 to 500℃, and it also prevents low temperature cracking that occurs during welding. and low carbon Cr-Mo with excellent high-temperature strength and weld cracking resistance that prevents SR cracking.
The purpose is to provide steel plates.
（課題を解決するための手段）
そこで、本発明者らは、３００〜５００℃で高い引張強
さを有し、耐低温割れ特性、耐ＳＲ割れ特性に優れる低
炭素Ｃｒ −Ｍｏ鋼板を得るために、低炭素Ｃｒ−Ｍｏ
鋼板を基本に鋭意研究を行い、下記の知見を得た。(Means for Solving the Problem) Therefore, the present inventors aimed to obtain a low carbon Cr-Mo steel sheet that has high tensile strength at 300 to 500°C and has excellent cold cracking resistance and SR cracking resistance. In, low carbon Cr-Mo
We conducted intensive research based on steel plates and obtained the following knowledge.
０３００〜５００°Ｃにおける引張強さをさらに上昇さ
せるには、■を添加し、炭化物を微細に析出させるのか
有効である。In order to further increase the tensile strength at 0300 to 500°C, it is effective to add (2) to cause fine precipitation of carbides.
■低炭素系の成分系においては、Ｓｉは強度を確保する
上て有効である。(2) In low carbon component systems, Si is effective in ensuring strength.
■■の添加による耐ＳＲ割れ特性の劣化を防止するには
、Ｓｏｌ、Ａｌ量を０．００３％未満に抑えるとか有効
である。In order to prevent the deterioration of the SR cracking resistance due to the addition of ■■, it is effective to suppress the amounts of Sol and Al to less than 0.003%.
■さらに、０を低く抑えることにより、Ｓｉ酸化物系の
介在物量を低く抑えることか可能であり、耐低温割れ特
性、耐ＳＲ割れ特性の低下および靭性の低下を防止する
のに有効である■上記の効果を最大限に得るには、焼き
ならしし時にフェライトの生成を抑えることか重要であ
り、このために、焼入れ性の向上に有効な固溶Ｂを活用
する。■Furthermore, by keeping 0 low, it is possible to keep the amount of Si oxide-based inclusions low, which is effective in preventing a decrease in cold cracking resistance, SR cracking resistance, and toughness.■ In order to maximize the above effects, it is important to suppress the formation of ferrite during normalizing, and for this purpose solid solution B, which is effective in improving hardenability, is utilized.
本発明は、これら５点の知見に基づいてなされたもので
、その第１発明は、Ｃ：０．０３〜０．１２％、Ｓｉ：
０．１５〜１．００％、Ｍｎ ：０．２０〜１．００％
、Ｐ：０．０２０％以下、Ｓ：０．００９％以下、Ｃｕ
：０．０５〜０．５０％、Ｎｌ：０．０５〜０．５０％
、Ｃｒ：０．４０〜３．５０％、Ｍｏ ：０．２０〜１
゜２５％、Ｖ：０．０９〜０．５０％、Ｓｏｌ、 ＡＩ
＋０．００３％未満、０・０、００３５％以下、Ｔｉ
：０．０１０〜０．０３０％、Ｂ：０．０００３〜０
、００２０％を含有し、残部Ｆｅおよび不可避不純物か
らなり、かつ、上記Ｔｉ、 Ｂか下記の式を満足する高
温強度および耐溶接割れ性に優れる低炭素Ｃｒ −Ｍｏ
鋼板である。The present invention has been made based on these five findings, and the first invention consists of C: 0.03-0.12%, Si:
0.15-1.00%, Mn: 0.20-1.00%
, P: 0.020% or less, S: 0.009% or less, Cu
: 0.05-0.50%, Nl: 0.05-0.50%
, Cr: 0.40-3.50%, Mo: 0.20-1
゜25%, V: 0.09-0.50%, Sol, AI
+0.003% or less, 0.0, 0035% or less, Ti
:0.010~0.030%, B:0.0003~0
, 0020%, with the balance consisting of Fe and unavoidable impurities, and which has excellent high temperature strength and weld cracking resistance and satisfies the above Ti, B or the following formula.
It is a steel plate.
０、２３Ｔｉ ＋Ｂ −０，７９Ｎ≧０．００（１３（
％）なお、Ｎは鋼中のＮ％を示す。0,23Ti +B -0,79N≧0.00(13(
%) Note that N indicates N% in the steel.
第２発明は、Ｎｂ：０．０１〜０．１０％、Ｃａ：０．
０００５〜０、０１００％の内から選んだ１種または２
種を含有する請求項（１）の高温強度および耐溶接割れ
性に優れる低炭素Ｃｒ −Ｍｏ鋼板である。The second invention has Nb: 0.01 to 0.10%, Ca: 0.
1 or 2 selected from 0005-0, 0100%
The low carbon Cr-Mo steel sheet of claim (1) contains seeds and has excellent high-temperature strength and weld cracking resistance.
６一 （作用） ６以下に、本発明について詳しく説明する。61 (effect) 6 The present invention will be explained in detail below.
まず、本発明の化学成分の限定理由について説明する。First, the reason for limiting the chemical components of the present invention will be explained.
Ｃは、鋼の強度および耐エロージヨン性を確保するため
に、本発明においては、０．０３％以上を添加すること
か必要であるか、その反面、Ｃ量の増加とともに、溶接
性および靭性か低下するのて、添加量の上限は０．１２
％とする。したかって、Ｃの添加量は０．０３〜０．１
２％の範囲とする。In order to ensure the strength and erosion resistance of steel, in the present invention, it is necessary to add 0.03% or more of C. On the other hand, as the amount of C increases, weldability and toughness decrease. The upper limit of the amount added is 0.12.
%. Therefore, the amount of C added is 0.03 to 0.1
The range shall be 2%.
Ｓｉは、強度の確保および耐酸化性の向上に有効である
ため、０．１５％以上添加するが、過剰に添加すると、
焼戻し脆化感受性を高めるので、添加量の上限は１．０
０％とする。したかって、Ｓｌの添加量は０．１５〜１
．００％の範囲とする。Si is effective in securing strength and improving oxidation resistance, so it is added in an amount of 0.15% or more, but if added in excess,
The upper limit of the amount added is 1.0 because it increases the susceptibility to tempering embrittlement.
Set to 0%. Therefore, the amount of Sl added is 0.15 to 1
．． 00% range.
Ｍｎは、鋼の強度と延性を高めるのに有効であるか、過
剰に添加すると溶接性か低下するので、添加量は０．２
０〜ｌ、００％の範囲とする。Is Mn effective in increasing the strength and ductility of steel? Excessive addition reduces weldability, so the amount added is 0.2
The range is 0 to l, 00%.
Ｐは、鋼中に不純物として含有されるが、靭性および溶
接性を損なうばかりでなく、焼戻し脆化感受性およびＳ
Ｒ割れ感受性を高めるため、低減することか望ましい。P is contained as an impurity in steel, but it not only impairs toughness and weldability, but also increases temper embrittlement susceptibility and S
It is desirable to reduce it in order to increase the sensitivity to R cracking.
したかって、本発明においては、Ｐの含有量は０．０２
０％以下とする。Therefore, in the present invention, the P content is 0.02
0% or less.
Ｓは、Ｐと同様に、鋼中に不純物として含有されるか、
鋼の靭性を著しく損ない、また、ＳＲ割れ感受性をも高
めるので、低減することが望ましく、したがって、Ｓの
含有量は０．００９％以下とする。Is S contained as an impurity in steel like P?
Since S significantly impairs the toughness of the steel and also increases the SR cracking susceptibility, it is desirable to reduce the S content. Therefore, the content of S is set to 0.009% or less.
Ｃｕは、固溶強化および析出強化による強度上昇に有効
な元素であり、かつ、耐エロージヨン性の向上にも効果
がある。このような効果を有効に発揮させるためには、
Ｃｕは少なくとも０．０５％以上を添加する必要がある
。一方、０．５０％を超えて過剰に添加すると、熱間加
工性が劣化する。したがって、Ｃｕの添加量は０．０５
〜０．５０％の範囲とする。Cu is an element effective in increasing strength through solid solution strengthening and precipitation strengthening, and is also effective in improving erosion resistance. In order to effectively demonstrate this effect,
It is necessary to add at least 0.05% of Cu. On the other hand, when added in excess of more than 0.50%, hot workability deteriorates. Therefore, the amount of Cu added is 0.05
The range is 0.50%.
Ｎｉは、鋼の焼入れ性を増し、また、耐エロージヨン性
の向上にも効果があり、さらに、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。このような効果を有効に発揮させるため
には、Ｎｉは０．０５％以上を添加する必要かあるか、
高価な元素であるので実用的な観点から、その添加量は
０．０５〜０．５０％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. Is it necessary to add 0.05% or more of Ni in order to effectively exhibit such an effect?
Since it is an expensive element, from a practical point of view, the amount added is in the range of 0.05 to 0.50%.
Ｃｒは、耐酸化性、焼戻し軟化抵抗を高め、強度を確保
するのに有効であるか、過剰に添加すると溶接性か劣化
する。したがって、Ｃｒの添加量は０゜４０〜３．５０
％の範囲とする。Cr is effective in increasing oxidation resistance and temper softening resistance and ensuring strength, but if added in excess, weldability deteriorates. Therefore, the amount of Cr added is 0°40~3.50
% range.
＾（０は、鋼の焼入れ性、特にＢと共存した場合の焼き
ならし時の焼入れ性を高めるのに不可欠な元素である。^(0 is an essential element for improving the hardenability of steel, especially the hardenability during normalizing when coexisting with B.
また、Ｍｏは焼戻し軟化抵抗を高め、高温強度の向上に
も有効であって、このためには、０．２０％以上添加す
る必要かあるか、高価な元素であるので、その添加量は
０．２０〜１．２５％の範囲とする。Furthermore, Mo is effective in increasing temper softening resistance and improving high-temperature strength, and for this purpose, it is necessary to add 0.20% or more, or since it is an expensive element, the amount added is 0. The range is .20 to 1.25%.
■は、微細な炭化物を析出することにより、高温強度を
高めるために最低０．０９％の添加か必要であるか、過
剰に添加すると溶接性や靭性を劣化させるのて、上限を
０．５０％とする。したかって、■の添加量は１０９〜
０．５０％の範囲とする。(2) is necessary to add a minimum of 0.09% to increase high-temperature strength by precipitating fine carbides, or to increase the upper limit to 0.50% because excessive addition deteriorates weldability and toughness. %. Therefore, the amount of addition of ■ is 109 ~
The range is 0.50%.
Ｓｏｌ、ＡＩは、従来、Ｂ添加鋼において、Ｂを有効に
活用するために、Ｎを固定する目的で添加されてきたが
、この方法は粒界に細かく連なった硫化物を生成させる
ため、耐ＳＲ割れ特性を低下させることになる。このた
め、Ｓｏｌ、ＡＩの添加量は０．００３％未満とする。Sol and AI have traditionally been added to B-added steel for the purpose of fixing N in order to effectively utilize B, but this method produces finely connected sulfides at grain boundaries, making it difficult to maintain durability. This will reduce the SR cracking characteristics. Therefore, the amount of Sol and AI added is less than 0.003%.
０は、Ｓｉを添加して、Ｓｏｌ、 ＡＩ量を低く抑えた
本発明鋼においては、Ｓｉ酸化物系の介在物を生成し、
耐低温割れ特性および耐ＳＲ割れ特性を低下させるとと
もに、靭性をも損なう。したかって、これらを防止する
ために、０の含有量は０．００３５％以下とする。0, in the steel of the present invention in which Si is added and the amounts of Sol and AI are kept low, Si oxide-based inclusions are generated,
It lowers cold cracking resistance and SR cracking resistance, and also impairs toughness. Therefore, in order to prevent these, the content of 0 is set to 0.0035% or less.
Ｂは、焼き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
添加することが必要である。しかし、Ｂは０．００２０
％を超えて過剰に添加するときは、焼きならし時にＢ化
合物を生成し、焼入れ性を低下させると同時に、耐ＳＲ
割れ性および靭性の劣化を伴う。したかって、Ｂの添加
量は０．０００３〜ｏ、 ｏ０２゜％の範囲とする。Since B improves the hardenability during normalizing and is effective in increasing strength, it is necessary to add 0.0003% or more in the steel of the present invention. However, B is 0.0020
If it is added in excess of more than
Accompanied by deterioration of crackability and toughness. Therefore, the amount of B added is in the range of 0.0003 to 0.02%.
Ｔ１は、強力な窒化物生成元素として、Ｎを固定＝１０
−
し、ＢかＮと反応するのを防ぎ、Ｂを固溶Ｂとすること
により、Ｂの焼入れ性向上効果を発現させる。本発明に
おいては、３００〜５００°Ｃにおける高温強度を確保
するため、焼きならし時にフェライトの生成を抑える必
要かあり、焼入れ性を高める固溶Ｂ量を確保する目的で
Ｔｉを添加する。T1 is a strong nitride-forming element with N fixed = 10
- By preventing B from reacting with N and making B a solid solution, the effect of improving the hardenability of B is exhibited. In the present invention, in order to ensure high-temperature strength at 300 to 500°C, it is necessary to suppress the formation of ferrite during normalizing, and Ti is added for the purpose of ensuring the amount of solid solution B that improves hardenability.
さらに、ＴｉはＳと結合して安定な硫化物を生成するこ
とによって、結晶粒界の固溶Ｓ量を低減して、耐ＳＲ割
れ特性を高める。このような効果を得るためには、Ｔ１
は０．０１０％以上添加する必要かあるが、０．０３０
％を超えて添加してもその効果か飽和するので、Ｔｉの
添加量は０．０１０〜０．０３０％の範囲とする。Furthermore, Ti combines with S to form stable sulfides, thereby reducing the amount of solid solution S at grain boundaries and improving SR cracking resistance. In order to obtain such an effect, T1
It is necessary to add 0.010% or more, but 0.030%
The effect of Ti is saturated even if it is added in an amount exceeding 0.010% to 0.030%.
なお、Ｔｉの添加量は下記式を満足しなければならない
。Note that the amount of Ti added must satisfy the following formula.
０．２３Ｔｉ＋Ｂ−０，７９Ｎ≧０．０００３ （％）
ただし、Ｎは鋼中のＮ％を示す。0.23Ti+B-0,79N≧0.0003 (%)
However, N indicates N% in the steel.
式中のＴｉは、添加Ｂ量から固溶Ｂ量を０．０００３％
以上確保するために、鋼中のＮを固定するに必要なＴｉ
量を示す。Ti in the formula is 0.0003% of the amount of solid solution B from the amount of added B.
In order to ensure the above, the amount of Ti necessary to fix N in the steel is
Indicate quantity.
本発明によるＣｒ −Ｍｏ鋼板は、上記の元素に加えて
Ｎｂ、 Ｃａを含有することかできる。The Cr-Mo steel sheet according to the present invention may contain Nb and Ca in addition to the above elements.
Ｎｂは、安定な炭窒化物を析出することにより、強度の
上昇に有効に作用する。このような効果を得るためには
、Ｎｂは０．０１％以上添加する必要があるか、０．１
０％を超えて添加しても効果か飽和するため、Ｎｂの添
加量は０．０１〜０．１０％の範囲とする。Nb effectively acts to increase strength by precipitating stable carbonitrides. In order to obtain such an effect, it is necessary to add Nb by 0.01% or more, or 0.1% or more.
Since the effect is saturated even if added in excess of 0%, the amount of Nb added is set in the range of 0.01 to 0.10%.
Ｃａは、結晶粒を微細化する効果を有するとともに、硫
化物を生成して、結晶粒界における固溶Ｓ景を低減させ
るため、耐ＳＲ割れ特性を一層高める。この効果を有効
に得るためには、Ｃａは０．０００５％以上添加するこ
とが必要であるか、過剰に添加するときは、非金属介在
物の量が増して、延性を低下させるので、上限は０．０
１００％とする。したがって、Ｃａの添加量は０．００
０５〜０．０１００％の範囲とする。Ca has the effect of refining crystal grains and also generates sulfide to reduce solid solution S formation at grain boundaries, thereby further enhancing the SR cracking resistance. In order to effectively obtain this effect, it is necessary to add 0.0005% or more of Ca, or if it is added in excess, the amount of nonmetallic inclusions increases and the ductility decreases, so the upper limit is is 0.0
Set to 100%. Therefore, the amount of Ca added is 0.00
The range is 0.05 to 0.0100%.
なお、Ｓｂ、 Ｓｎ、 Ａｓ等の不純物元素は、従来か
ら耐ＳＲ割れ特性を劣化させることが知られている。し
たがって、本発明においても、これらの元素は、それぞ
れ０．０１％以下とすることが好ましい。Note that impurity elements such as Sb, Sn, and As have been known to degrade SR cracking resistance. Therefore, also in the present invention, it is preferable that each of these elements be 0.01% or less.
本発明によるＣｒ−Ｍｏ鋼板を製造するには、本発明で
限定する化学成分を含有する鋼片を、常法にしたかって
製造し、これを熱間圧延し、その後、引き続いて熱処理
を行えばよい。In order to produce the Cr-Mo steel sheet according to the present invention, a steel billet containing the chemical components defined in the present invention is produced in a conventional manner, hot rolled, and then heat treated. good.
（実施例）
以下に実施例を挙げて本発明を説明するか、本発明はこ
れら実施例により何ら限定されるものではない。(Examples) The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way.
第１表に示す化学成分を含有する本発明鋼および比較鋼
の機械的性質、耐低温割れ特性および耐ＳＲ割れ特性を
第２表に示す。耐低温割れ特性および耐ＳＲ割れ特性は
、板厚２５ｍｍの斜めＹ形溶接割れ試験片を用いて求め
たものである。Table 2 shows the mechanical properties, cold cracking resistance, and SR cracking resistance of the invention steel and comparative steel containing the chemical components shown in Table 1. The cold cracking resistance and the SR cracking resistance were determined using a diagonal Y-shaped weld cracking test piece with a plate thickness of 25 mm.
（以下余白）
第２表に示すように、本発明による鋼板Ａ〜Ｅ′は、３
００〜５００°Ｃの高温において、高い引張強さを有し
テイル。例えば、ＡＳＭＥ ５ＥＣＴ［ＯＮ ＭＩ［
ＤＩＶ［５ＩＯＮ １の最大許容応力の４倍（３００℃
て５０．２ｋｇｆ／ｍｍ２．４００°Ｃて４８．４ｋｇ
ｆ／ｍｍ”、５００°Ｃて３５．７ｋｇｆ／ｍｍ２）を
上回る値が得られている。さらに、鋼板Ａ〜Ｅは、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１
００°Ｃ以下であり、また、ＳＲ割れ率も６％以下であ
る。(Hereinafter, blank space) As shown in Table 2, the steel plates A to E' according to the present invention are 3
Tail with high tensile strength at high temperatures of 00-500°C. For example, ASME 5ECT[ON MI[
DIV[5ION 4 times the maximum allowable stress of 1 (300℃
50.2kgf/mm2.48.4kg at 400°C
f/mm", and 35.7 kgf/mm2 at 500°C.Furthermore, for steel plates A to E, the root crack prevention preheating temperature in the diagonal Y-shaped weld cracking test was 1.
00°C or less, and the SR cracking rate is also 6% or less.
これに対して、比較鋼Ｆは、従来から知られているＣ量
０．１４％の鋼板であり、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１７５°Ｃてあって、低炭
素鋼板に比較して高い予熱温度を必要とする。比較鋼Ｇ
は、■を含有しない低炭素鋼板であり、３００〜５００
°Ｃにおける高温強度が低い値となっている。同様に、
比較鋼Ｈは、Ｓｌを低く抑えているため十分な高温強度
が得られない。比較鋼■は、Ｓｏｌ、ＡＩ量か高い場合
の例であり、高温強度、耐低温割れ特性に関しては十分
な特性か得られているが、耐ＳＲ割れ特性が劣っている
。比軟鋼Ｊは、Ｔｉ、 Ｂの添加量か不適切で、式
０．２３Ｔｉ＋８−０．７９Ｎ≧０．０００３ （％）
を満足しない場合の例である。したがって、Ｂの焼入れ
性向上効果を活用できず、焼きならし時にフェライトか
析出するため、常温、高温ての強度か低い。On the other hand, Comparative Steel F is a conventionally known steel plate with a C content of 0.14%, and the preheating temperature for preventing root cracking in the diagonal Y-shaped weld cracking test is 175°C. Requires higher preheating temperature compared to Comparative steel G
is a low carbon steel plate that does not contain ■, and has a carbon content of 300 to 500
The high temperature strength at °C is a low value. Similarly,
Comparative Steel H does not have sufficient high-temperature strength because the Sl content is kept low. Comparative steel (3) is an example in which the Sol and AI contents are high, and although sufficient properties are obtained in terms of high temperature strength and cold cracking resistance, the SR cracking resistance is poor. Specific mild steel J has an inappropriate addition amount of Ti and B, and the formula
0.23Ti+8-0.79N≧0.0003 (%)
This is an example of a case where the following is not satisfied. Therefore, the hardenability improving effect of B cannot be utilized, and ferrite precipitates during normalization, resulting in low strength at room temperature and high temperature.
比較鋼には、０量か高いため、耐低温割れ特性および耐
ＳＲ割れ特性か劣るとともに、靭性も低くなっている。Since the comparative steel has a high content of 0, it has poor cold cracking resistance and SR cracking resistance, as well as low toughness.
（発明の効果） 以上説明したように、本発明は、低炭素Ｃｒ −Ｍ。(Effect of the invention) As explained above, the present invention is directed to low carbon Cr-M.
鋼板において、Ｓｏｌ、ＡＩ量を０．００３％未満に、
０量を０．００３５％以下に規制することによって、Ｓ
Ｒ割れを防止し、さらに、Ｔｉの添加により固溶Ｂを存
効に活用して、母材および高温強度を確保し、かつ、Ｓ
ｉ、 Ｃｕ、 Ｎｉ、 Ｖを複合添加することにより
高温強度を確保するもので、本発明によれば、３００〜
５００°Ｃて高い引張強さを有するとともに、溶接時に
生じる低温割れおよびＳＲ割れを防止した高温強度およ
び耐溶接割れ性に優れる低炭素Ｃｒ−ＭＯ鋼板を得るこ
とができる。In the steel plate, the amount of Sol and AI is less than 0.003%,
By regulating the amount of 0.0035% or less, S
It prevents R cracking, and also makes effective use of solid solution B by adding Ti to ensure the base metal and high temperature strength.
High temperature strength is ensured by adding i, Cu, Ni, and V in a composite manner, and according to the present invention, the strength is 300~
It is possible to obtain a low carbon Cr-MO steel sheet that has high tensile strength at 500°C, and has excellent high-temperature strength and weld cracking resistance that prevents low-temperature cracking and SR cracking that occur during welding.
Claims (2)
．００％、Ｍｎ：０．２０〜１．００％、Ｐ：０．０２
０％以下、Ｓ：０．００９％以下、Ｃｕ：０．０５〜０
．５０％、Ｎｉ：０．０５〜０．５０％、Ｃｒ：０．４
０〜３．５０％、Ｍｏ：０．２０〜１．２５％、Ｖ：０
．０９〜０．５０％、Ｓｏｌ．Ａｌ：０．００３％未満
、Ｏ：０．００３５％以下、Ｔｉ：０．０１０〜０．０
３０％、Ｂ：０．０００３〜０．００２０％を含有し、
残部Ｆｅおよび不可避不純物からなり、かつ、上記Ｔｉ
、Ｂが下記の式を満足することを特徴とする高温強度お
よび耐溶接割れ性に優れる低炭素Ｃｒ−Ｍｏ鋼板。 ０．２３Ｔｉ＋Ｂ−０．７９Ｎ≧０．０００３（％）た
だし、Ｎは鋼中のＮ％を示す。(1) C: 0.03-0.12%, Si: 0.15-1
．． 00%, Mn: 0.20-1.00%, P: 0.02
0% or less, S: 0.009% or less, Cu: 0.05-0
．． 50%, Ni: 0.05-0.50%, Cr: 0.4
0-3.50%, Mo: 0.20-1.25%, V: 0
．． 09-0.50%, Sol. Al: less than 0.003%, O: 0.0035% or less, Ti: 0.010 to 0.0
30%, B: 0.0003 to 0.0020%,
The remainder consists of Fe and unavoidable impurities, and the above Ti
A low carbon Cr-Mo steel sheet having excellent high-temperature strength and weld cracking resistance, characterized in that , B satisfy the following formula. 0.23Ti+B-0.79N≧0.0003(%) However, N indicates N% in the steel.
５〜０．０１００％の内から選んだ１種または２種を含
有することを特徴とする請求項（１）の高温強度および
耐溶接割れ性に優れる低炭素Ｃｒ−Ｍｏ鋼板。(2) Nb: 0.01-0.10%, Ca: 0.000
The low carbon Cr-Mo steel sheet having excellent high-temperature strength and weld cracking resistance according to claim 1, characterized in that it contains one or two selected from 5 to 0.0100%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31192690A JP2857248B2 (en) | 1990-11-16 | 1990-11-16 | Low carbon Cr-Mo steel sheet with excellent high temperature strength and weld crack resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31192690A JP2857248B2 (en) | 1990-11-16 | 1990-11-16 | Low carbon Cr-Mo steel sheet with excellent high temperature strength and weld crack resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04183842A true JPH04183842A (en) | 1992-06-30 |
| JP2857248B2 JP2857248B2 (en) | 1999-02-17 |
Family
ID=18023096
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31192690A Expired - Lifetime JP2857248B2 (en) | 1990-11-16 | 1990-11-16 | Low carbon Cr-Mo steel sheet with excellent high temperature strength and weld crack resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2857248B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008510037A (en) * | 2004-08-11 | 2008-04-03 | イー・アイ・デュポン・ドウ・ヌムール・アンド・カンパニー | Removal of fluorosurfactants from aqueous fluoropolymer dispersions using sorbent pouches |
-
1990
- 1990-11-16 JP JP31192690A patent/JP2857248B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008510037A (en) * | 2004-08-11 | 2008-04-03 | イー・アイ・デュポン・ドウ・ヌムール・アンド・カンパニー | Removal of fluorosurfactants from aqueous fluoropolymer dispersions using sorbent pouches |
| JP4838799B2 (en) * | 2004-08-11 | 2011-12-14 | イー・アイ・デュポン・ドウ・ヌムール・アンド・カンパニー | Removal of fluorosurfactants from aqueous fluoropolymer dispersions using sorbent pouches |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2857248B2 (en) | 1999-02-17 |
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