JPH09296249A - Chromium-molybdenum steel - Google Patents
Chromium-molybdenum steelInfo
- Publication number
- JPH09296249A JPH09296249A JP11145796A JP11145796A JPH09296249A JP H09296249 A JPH09296249 A JP H09296249A JP 11145796 A JP11145796 A JP 11145796A JP 11145796 A JP11145796 A JP 11145796A JP H09296249 A JPH09296249 A JP H09296249A
- Authority
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- Prior art keywords
- steel
- cracking
- strength
- reheat cracking
- cracking 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.)
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- Heat Treatment Of Steel (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は石油化学、石油精製
等の高温高圧水素環境下で使用される圧力容器等や、ボ
イラ等の発電プラント設備の高温高圧下で使用される大
径厚肉管等の用途に用いる、強度・靭性を確保した上で
溶接時の低温割れ性とその後の溶接後熱処理(以下PW
HTという)中に生じる再熱割れを改善したCr−Mo
鋼に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure vessel or the like used in a high temperature and high pressure hydrogen environment such as petrochemical and petroleum refining, or a large diameter thick wall tube used under high temperature and high pressure in a power plant facility such as a boiler. Used for such purposes as ensuring strength and toughness, cold cracking during welding and subsequent heat treatment after welding (hereinafter PW
Cr-Mo with improved reheat cracking that occurs in (HT)
Regarding steel.
【0002】[0002]
【従来の技術】圧力容器や大径厚肉管等用の2 1/4Cr
−1Mo鋼(JIS SCMV4等)に代表されるCr
−Mo鋼は、熱間圧延/あるいは熱間加工後、焼ならし
−焼戻し、または焼入れ−焼戻し、或は、熱間圧延/あ
るいは熱間加工後直後焼入れまたは空冷−焼もどしによ
り製造され、さらに冷間や温間、熱間加工等とも組み合
わされ、最終的に溶接に組み立てられ、その後PWHT
が施される。この鋼種では、溶接に際して、通常150
℃から250の予熱が必要であり、従来よりその負荷軽
減が望まれていた。2. Description of the Related Art 2 1/4 Cr for pressure vessels and large diameter thick tubes
Cr represented by -1Mo steel (JIS SCMV4 etc.)
-Mo steel is produced by hot rolling / or hot working, followed by normalization-tempering, or quenching-tempering, or immediately after hot rolling / or hot working or by air cooling-tempering. Combined with cold, warm, hot working etc., finally assembled into welding, then PWHT
Is applied. With this type of steel, it is usually 150 when welding.
Preheating from ℃ to 250 is required, and reduction of the load has been desired conventionally.
【0003】そこで、特公昭64-7128 号公報に開示され
ている如く、Ti、Bの添加とN含有量の規制の組み合
わせとV、Nb等の添加による析出強化の増大により強
度・靭性を確保した上でのC量の低減を可能にし、溶接
低温割れ性を改善する方法が提案されている。また、特
公昭64-7127 号公報や特公平1-29853 号公報では、さら
にCu、Ni等の添加や直接焼入れ−焼戻しの実施によ
っても強度・靭性の向上が図られることが述べられてい
る。Therefore, as disclosed in JP-B-64-7128, strength and toughness are secured by a combination of addition of Ti and B and regulation of N content and increase of precipitation strengthening by addition of V and Nb. In addition, a method has been proposed in which the C content can be reduced and the welding cold cracking property is improved. Further, JP-B-64-7127 and JP-B1-29853 describe that the strength and toughness can be improved by further adding Cu, Ni or the like or performing direct quenching-tempering.
【0004】ところが、これらのCu、NiやTi、
B、Nb、Vの添加は溶接施工後のPWHT時に起こる
再熱割れ感受性を高めることがよく知られている。2 1
/4Cr−1Mo鋼は一般的に1 1/4Cr− 1/2Mo鋼や
1Cr− 1/2Mo鋼より再熱割れは起きにくいとされて
いるが、これらの元素が多量に添加されている場合、特
に、拘束条件の厳しい箇所では再熱割れが施工上の大き
な問題となることがある。However, these Cu, Ni and Ti,
It is well known that the addition of B, Nb and V enhances the susceptibility to reheat cracking that occurs during PWHT after welding. Two one
/ 4Cr-1Mo steel is generally said to be less prone to reheat cracking than 1 1 / 4Cr-1 / 2Mo steel and 1Cr-1 / 2Mo steel, but when a large amount of these elements is added, In particular, reheat cracking may become a serious problem in construction in places where the constraint conditions are severe.
【0005】そこで、低C−Cu、Ni、V添加Ti−
B系Cr−Mo鋼板の耐溶接低温割れ性および耐再熱割
れ性改善に関しては、特開平5-1351号公報に開示されて
いる通り、(Cu+Ni/2+V)/Cr量の規制と極
低Al化により耐再熱割れ性が改善されると述べられて
いる。また、特開平4-183842号公報では同鋼種に対し
て、V含有量がより高い場合(0.09〜0.50w
t.%)において、極低Al化により耐再熱割れ性が改
善されると述べられている。Therefore, low C-Cu, Ni, and V-added Ti-
Regarding the improvement of the weld cold cracking resistance and reheat cracking resistance of the B-based Cr-Mo steel sheet, as disclosed in JP-A-5-1351, (Cu + Ni / 2 + V) / Cr amount regulation and extremely low Al content It is said that the reheating cracking resistance is improved by the chemical conversion. Further, in Japanese Patent Laid-Open No. 4-184842, when the V content is higher than that of the same steel type (0.09 to 0.50w).
t. %), It is stated that the resistance to reheat cracking is improved by making extremely low Al.
【0006】[0006]
【発明が解決しようとする課題】ところが、特開平5-13
51号号公報および特開平4-183842号公報に開示されてい
る極低Alにすると、現状の製造方法では酸素レベルが
比較的高くなり易く、鋼の清浄性の低下や靭性の劣化が
問題となる。また、最近のプラントの高効率化の志向に
よる使用条件の高温高圧化や装置の大型化に伴い、鋼板
の板厚は厚肉化される傾向になるが、板厚が厚くなるほ
ど、一般的に、強度靭性の確保が困難であり、特開平5-
1351号公報では特に厚肉向けに成分設計された成分系と
は言えない。実際、特開平5-1351号公報で開示されてい
る実施例の板厚は25mmとなっている。また、V添加
量の0.09%未満に制限されており、Vを0.10%
以上含有した高強度鋼では十分な耐再熱割れ性が確保さ
れないことになっている。[Problems to be Solved by the Invention] However, JP-A-5-13
When the ultra-low Al disclosed in Japanese Patent No. 51 and Japanese Patent Application Laid-Open No. 4-183842 is used, the oxygen level tends to be relatively high in the current manufacturing method, and deterioration of steel cleanliness and deterioration of toughness are problems. Become. In addition, with the recent trend toward higher efficiency of plants and higher temperature and pressure of operating conditions and larger size of equipment, the thickness of steel sheets tends to become thicker. However, it is difficult to secure strength and toughness, and
In 1351 gazette, it cannot be said that the component system is designed specifically for thick wall. In fact, the plate thickness of the example disclosed in Japanese Patent Laid-Open No. 5-1351 is 25 mm. Also, it is limited to less than 0.09% of V addition amount, and V is 0.10%.
With the high strength steels contained above, sufficient reheat cracking resistance cannot be ensured.
【0007】一方、特開平4-183842号公報では、V含有
量が0.09〜0.50wt%と高く、厚肉材向けでは
あるが、特開平5-1351号公報と比べてみるとVがより多
いにも関わらず(Cu+Ni/2+V)/Cr量の規制
がなく、特開平5-1351号公報によるとこの成分系では再
熱割れ感受性は改善できないという矛盾がある。したが
って、V量が0.10%以上の厚肉用の成分系では再熱
割れ性を確保しているとは言えない。On the other hand, in Japanese Patent Application Laid-Open No. 4-183842, the V content is as high as 0.09 to 0.50 wt%, which is for thick materials, but when compared with Japanese Patent Application Laid-Open No. 5-1351. However, there is no regulation of the amount of (Cu + Ni / 2 + V) / Cr, but according to Japanese Patent Laid-Open No. 5-3511, there is a contradiction that the reheat cracking susceptibility cannot be improved by this component system. Therefore, it cannot be said that the reheat cracking property is secured in the component system for thick wall with the V content of 0.10% or more.
【0008】本発明は、上記事情に鑑みてなされたもの
で、Cr−Mo鋼の厚肉材において、強度・靭性を確保
しつつ、耐溶接低温割れを大幅に改善するとともに、耐
再熱割れ性も併せて改善することを目的とする。The present invention has been made in view of the above circumstances, and in a thick-walled Cr-Mo steel material, while securing strength and toughness, the cold cracking resistance to welding is significantly improved and the reheat cracking resistance is also improved. The purpose is also to improve sex.
【0009】[0009]
【課題を解決するための手段】すなわち本発明は、重量
%で、C:0.03〜0.08%、Si:0.01〜
0.8%、Mn:0.05〜1%、P:≦0.015
%、S:≦0.003%、Cu:0.05〜1%、N
i:0.05〜1%、Cr:2.0〜3.5%、Mo+
1/2W:0.5〜1.5%、V:0.05〜0.5
%、Ti:0.005〜0.03%、B:0.0003
〜0.003%、Al:0.003〜0.035%、
N:≦0.006%、O:≦0.005%、Ca:0.
0005〜0.005%を含有し、更に、必要によりN
b:≦0.10%を含有し、かつ0.5<Cu%+Ni
%<1.2,及び1<Ca%/S%<10の関係を満足
し、残部は不可避的不純物及び鉄からなることを特徴と
する耐溶接低温割れ性及耐再熱割れ性に優れたCr−M
o鋼である。That is, according to the present invention, in% by weight, C: 0.03 to 0.08%, Si: 0.01 to.
0.8%, Mn: 0.05 to 1%, P: ≤ 0.015
%, S: 0.003%, Cu: 0.05 to 1%, N
i: 0.05 to 1%, Cr: 2.0 to 3.5%, Mo +
1 / 2W: 0.5-1.5%, V: 0.05-0.5
%, Ti: 0.005 to 0.03%, B: 0.0003
~ 0.003%, Al: 0.003 to 0.035%,
N: ≦ 0.006%, O: ≦ 0.005%, Ca: 0.
0005 to 0.005%, and if necessary N
b: contains ≦ 0.10% and 0.5 <Cu% + Ni
% Welding cold cracking resistance and reheat cracking resistance, which are characterized by satisfying the relationships of% <1.2 and 1 <Ca% / S% <10, and the balance consisting of inevitable impurities and iron. Cr-M
o Steel.
【0010】[0010]
【発明の実施の形態】以下に本発明について詳しく説明
する。BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
【0011】本発明の基本的な構成は下記の通りであ
る。The basic structure of the present invention is as follows.
【0012】(1)極低C化により、厚肉材においても
溶接低温割れ性を大幅に改善する。(1) The extremely low carbon content greatly improves the weld cold cracking property even in thick-walled materials.
【0013】(2)厚肉材での強度・靭性を確保するた
め、微量Bを添加し、Nを低く規制しかつTi添加によ
り焼ならしあるいは焼入れ時に固溶Bを確保し、焼入性
を確保する。 (3)V(またはこれに加えて微量Nb)を適量添加し
て耐再熱割れ性を劣化させることなく、炭窒化物を微細
に析出させ強度を上昇させる。 (4)適量のCu+Ni添加(0.5%〜1.2%)に
より耐再熱割れ性を劣化させることなく焼入性を向上さ
せ、強度を上昇させる。 (5)S低く抑えると共にCaを添加し固溶Sを固定
し、且つ、酸化物系介在物の形態の制御により再熱割れ
性を改善する。ここで、Caの後者の効果を最大限に引
き出すため、酸素レベルは低く抑えるとともに、Al添
加量を制御する。 上記目的のため、本発明の化学成分を以下のように限定
する。(2) In order to secure the strength and toughness of thick-walled materials, a trace amount of B is added, N is regulated to a low level, and Ti is added to secure solid solution B during normalization or quenching. Secure. (3) V (or a small amount of Nb in addition thereto) is added in an appropriate amount to finely precipitate the carbonitride and increase the strength without deteriorating the reheat cracking resistance. (4) By adding an appropriate amount of Cu + Ni (0.5% to 1.2%), the hardenability is improved and the strength is increased without deteriorating the reheat cracking resistance. (5) S is suppressed to a low level, Ca is added to fix the solid solution S, and the reheat cracking property is improved by controlling the form of oxide inclusions. Here, in order to maximize the latter effect of Ca, the oxygen level is kept low and the amount of Al added is controlled. For the above purpose, the chemical components of the present invention are limited as follows.
【0014】C:Cは強度確保の点から0.03%以上
必要であるが、増加に伴い溶接低温割れ性は増大するた
め、上限を0.08%とする。C: C is required to be 0.03% or more from the viewpoint of securing the strength, but since the weld cold cracking property increases with the increase, the upper limit is made 0.08%.
【0015】Si:Siは強度の確保及び耐酸化性の向
上に有効であるが、同時に靭性劣化及び焼戻し脆化感受
性を増大させるため、0.01%≦Si≦0.8%とす
る。Si: Si is effective for securing strength and improving oxidation resistance, but at the same time increases toughness deterioration and susceptibility to temper embrittlement, so 0.01% ≤Si≤0.8%.
【0016】Mn:Mnは強度・靭性を上昇させるのに
有効であるが、同時に約戻し脆化感受性を増大させるた
め、0.05%≦Mn≦1%とする。Mn: Mn is effective in increasing the strength and toughness, but at the same time increases the back embrittlement susceptibility, so that 0.05% ≦ Mn ≦ 1%.
【0017】P:Pは焼戻し脆性を助長し靭性を損ねる
と共に再熱割れ感受性を高めるため、0.015%以下
とする。P: P is 0.015% or less in order to promote temper embrittlement, impair toughness and enhance reheat cracking susceptibility.
【0018】S:Sは再熱割れ感受性を高めるため、
0.003%以下とする。S: S enhances reheat cracking susceptibility,
It is made 0.003% or less.
【0019】Cu:Cuは焼入性を高め、また、固溶強
化元素として強度を高めるので0.05%以上添加する
が、過剰に添加すると再熱割れ性を高め、またクリープ
延性や熱間加工性を低下させるので、上限を1%とす
る。Cu: Cu enhances hardenability and strengthens as a solid solution strengthening element, so 0.05% or more is added. However, if added in excess, reheat crackability is enhanced, and creep ductility and hot workability are increased. Since the workability is reduced, the upper limit is 1%.
【0020】Ni:Niは焼入性を向上させると共に靭
性を改善に有効であるので0.05%以上添加するが、
過剰に添加すると再熱割れ感受性を高めるので、上限を
1%とする。Ni: Ni is effective in improving hardenability and toughness, so 0.05% or more is added.
If added excessively, reheat cracking susceptibility is increased, so the upper limit is made 1%.
【0021】さらに、本発明においては低C化された厚
肉材での強度・靭性を確保するため、Cu+Ni量を
0.5%以上とし、上限は再熱割れ感受性当への悪影響
から1.2%以下に制限する。Further, in the present invention, in order to secure the strength and toughness of a thick material having a low carbon content, the amount of Cu + Ni is set to 0.5% or more, and the upper limit is 1. Limit to 2% or less.
【0022】Cr:Crは高温用鋼にとって重要な性能
である高温強度、耐水素アタック性、耐酸化性に対して
有効であり、2.0%以上含有させることが必要である
が、一方、コスト及び溶接性の観点から3.5%を上限
とする。Cr: Cr is effective for high temperature strength, hydrogen attack resistance and oxidation resistance, which are important performances for high temperature steel, and it is necessary to contain Cr in an amount of 2.0% or more. From the viewpoint of cost and weldability, the upper limit is 3.5%.
【0023】MoおよびW:MoおよびWは安定的に炭
化物を生成するためにCrと同様に高温強度、クリープ
強度、耐水素アタック性に対して有効であるが、極端な
添加は溶接性を害し経済性を損なうため、0.5%≦M
o+ 1/2W≦1.5%とする。ここでWはMoの2倍の
原子量を有することから、MoとW/2は等価であると
考えられる。Mo単独でもW単独でも、高温強度等に有
効であるが、Wの割合の高い方がより効果は大きい。Mo and W: Mo and W are effective in high temperature strength, creep strength and hydrogen attack resistance like Cr because they stably form carbides, but extreme addition impairs weldability. 0.5% ≦ M to impair economy
o + 1 / 2W ≦ 1.5%. Here, since W has twice the atomic weight of Mo, it is considered that Mo and W / 2 are equivalent. Although Mo alone and W alone are effective for high temperature strength and the like, the higher the W content, the greater the effect.
【0024】V:Vは炭化物生成元素であり強度を上昇
させることができるが、過剰に添加した場合、再熱割れ
感受性を高めるので、0.05%≦V≦0.5%とす
る。V: V is a carbide-forming element and can increase the strength, but when it is added in excess, it increases the reheat cracking susceptibility, so 0.05% ≤V≤0.5%.
【0025】Ti:Tiは強窒化物生成元素であり、N
を固定することによりBの焼入向上効果を高めるが、過
剰に存在すると靭性を低下させるため0.005%≦T
i≦0.05%とする。Ti: Ti is a strong nitride forming element, and N
The effect of improving the quenching of B is enhanced by fixing B. However, if it is present excessively, the toughness decreases, so 0.005% ≦ T
i ≦ 0.05%.
【0026】S.Al:S.Alは低く抑えることによ
り、再熱割れ感受性を改善するが0.005%未満にす
ると靭性を損なうばかりでなく、Caの再熱割れ性を改
善する効果を小さくさせるため、0.005%以上とす
る。また、過剰に添加すると、再熱割れ感受性を高める
とともに高温強度を低下させるので上限を0.035%
とする。S. Al: S. By suppressing Al to a low level, the reheat cracking susceptibility is improved, but if it is less than 0.005%, not only the toughness is impaired, but also the effect of improving the reheat cracking property of Ca is reduced, so 0.005% or more. To do. Further, if added excessively, the reheat cracking susceptibility is increased and the high temperature strength is lowered, so the upper limit is 0.035%.
And
【0027】N:NはBと結び付きやすく固溶B量を減
少させ焼入れ性を低下させるので0.006%以下に低
く抑える。N: N easily binds to B, reduces the amount of solid solution B, and deteriorates hardenability, so it is kept to 0.006% or less.
【0028】O:Oは酸化物系介在物の生成による延靭
性や溶接性の低下を防止し、また、Caの酸化物系介在
物の制御による再熱割れ性改善の効果を最大限に引き出
すため、0.005%以下と低く抑える。O: O prevents deterioration of ductility and weldability due to the formation of oxide inclusions, and maximizes the effect of improving reheat cracking resistance by controlling oxide inclusions of Ca. Therefore, it is kept low at 0.005% or less.
【0029】Nb:Nbは安定は炭窒化物生成元素であ
り強度を上昇させることができるが、過剰に含有させる
と靭性や溶接性を損ねるとともに、再熱割れ感受性を高
めるので、0.005%≦Nb≦0.10%とする。Nb: Nb is a carbonitride-forming element that is stable and can increase the strength. However, if it is contained excessively, the toughness and weldability are impaired, and the reheat cracking susceptibility is increased. ≦ Nb ≦ 0.10%.
【0030】Ca:Caは強硫化物生成元素であり、鋼
中の固溶Sを固定し再熱割れ感受性を改善する。さら
に、後で述べるようにS.Al量との適正化により酸化
物系介在物を制御し、再熱割れ性を改善する。この場
合、後者の効果が非常に大きい。そこで0.0005%
≦Ca≦0.005%とする。Ca: Ca is a strong sulfide-forming element, which fixes solid solution S in steel and improves reheat cracking susceptibility. Furthermore, as will be described later, S. By adjusting the amount of Al appropriately, oxide inclusions are controlled and reheat cracking property is improved. In this case, the latter effect is very large. 0.0005%
≦ Ca ≦ 0.005%.
【0031】Ca/S:Caの再熱割れ性改善効果を十
分に得るため、Ca/Sの比を1以上10以下とする。
すなわち、本発明者らは、Ca、S、S.Alの関係に
ついて検討した。その結果を図1に示す。図中、○で囲
まれた数字はCa/Sの値を示し,斜線の範囲はy割れ
試験による再熱割れ率が10%以下を示す。図1から,
S.Al含有量とCa含有量が所定範囲にあり,かつ、
1<Ca/S<10において,y割れ試験による再熱割
れ率を10%以下にすることができることを見いだし
た。ここで,再熱割れ率は,JIS Z3158に規定
するy形溶接割れ試験を行い、再熱割れの起こりやすい
温度である620℃×12hの厳しい条件でPWHTを
行い、その後の断面割れ率で評価した。Ca / S: In order to sufficiently obtain the effect of improving the reheat cracking resistance of Ca, the ratio of Ca / S is set to 1 or more and 10 or less.
That is, the present inventors have found that Ca, S, S. The relationship of Al was examined. The result is shown in FIG. In the figure, the numbers circled indicate the values of Ca / S, and the shaded areas indicate that the reheat cracking rate in the y cracking test is 10% or less. From Figure 1
S. Al content and Ca content are within a predetermined range, and
It was found that in 1 <Ca / S <10, the reheat cracking ratio by the y cracking test can be made 10% or less. Here, the reheat cracking rate is determined by performing a y-type weld cracking test specified in JIS Z3158, performing PWHT under severe conditions of 620 ° C. × 12 h, which is a temperature at which reheat cracking easily occurs, and then evaluating the cross-sectional cracking rate. did.
【0032】本発明によるCr−Mo鋼を製造するに
は、必要とする機械的性質に応じて熱間圧延および/あ
るいは熱間加工後焼ならしあるいは焼入れを行い焼戻し
を行うか、あるいは熱間圧延または熱間加工後直接焼入
れまたは空冷し焼戻しを行えばよい。In order to produce the Cr-Mo steel according to the present invention, depending on the required mechanical properties, hot rolling and / or hot working is followed by normalizing or quenching to perform tempering, or hot rolling. After rolling or hot working, direct quenching or air cooling and tempering may be performed.
【0033】その他Sn、As、Sb等の不純物元素は
再熱割れ感受性およびクリープ脆化感受性を増大させる
ため0.01以下と低くすることが好ましい。Other impurity elements such as Sn, As, and Sb increase the susceptibility to reheat cracking and the susceptibility to creep embrittlement, and are therefore preferably set to 0.01 or less.
【0034】[0034]
【実施例】以下,本発明の実施例を説明する。EXAMPLES Examples of the present invention will be described below.
【0035】(製造条件) 板厚:50mm 圧延条件:1200℃加熱−1000℃仕上げ(圧延後
空冷) 焼ならし:冷却速度をコントロール(150mm空冷材の
1/2 tの冷却速度) 焼戻し:720℃ 本発明鋼1のみ焼ならしを省略したTMCP−Tタイプ
も併せて実施した。 溶接後熱処理(PWHT):700℃×24h(母材特
性) 620℃×12h(再熱割れ試験) (試験条件) 再熱割れ試験方法 JIS Z3158(y形溶接割れ試験)に準拠 50mm厚 テストビード→PWHT→割れ観察(断面割れ) 再熱割れ試験はy割れタイプの拘束条件の厳しい試験片
で行い、PWHT条件は徐加熱を行い、最も再熱割れの
起こりやすい温度(600〜650℃)で保持してい
る。保持時間はこれ以上長くしても、HAZの軟化のた
め、割れは進展しない。これは非常に厳しい試験条件で
ある。本発明鋼および比較鋼の組成を表1〜3に,試験
条件,試験結果を表4〜表7に示す。(Manufacturing conditions) Plate thickness: 50 mm Rolling conditions: 1200 ° C. heating-1000 ° C. finishing (air cooling after rolling) Normalizing: Cooling rate controlled (150 mm of air-cooled material)
Cooling rate of 1/2 t) Tempering: 720 ° C. A TMCP-T type in which only normalizing of the invention steel 1 was omitted was also performed. Post-weld heat treatment (PWHT): 700 ° C. × 24 h (base material properties) 620 ° C. × 12 h (reheat cracking test) (test conditions) Reheat cracking test method According to JIS Z3158 (y-type weld cracking test) 50 mm thick test bead → PWHT → Observation of cracks (cross-section crack) The reheat cracking test is performed on a y-crack type test piece with severe restraint conditions, and the PWHT condition is gradual heating at the temperature (600 to 650 ° C) where reheat cracking is most likely keeping. Even if the holding time is made longer than this, the HAZ is softened and the crack does not progress. This is a very stringent test condition. The compositions of the present invention steel and comparative steel are shown in Tables 1 to 3, and the test conditions and test results are shown in Tables 4 to 7.
【0036】[0036]
【表1】 [Table 1]
【0037】[0037]
【表2】 [Table 2]
【0038】[0038]
【表3】 [Table 3]
【0039】[0039]
【表4】 [Table 4]
【0040】[0040]
【表5】 [Table 5]
【0041】[0041]
【表6】 [Table 6]
【0042】[0042]
【表7】 [Table 7]
【0043】[0043]
【発明の効果】以上の結果から明らかなように,本発明
によれば、Cr−Mo鋼材において、強度・靭性を確保
しつつ、耐溶接低温割れを大幅に改善するとともに、耐
再熱割れ性も併せて改善することができ,石油化学、石
油精製等の高温高圧水素環境下で使用される圧力容器等
や、ボイラ等の発電プラント設備の高温高圧下で使用さ
れる大径厚肉管等の用途に極めて有効である。As is clear from the above results, according to the present invention, in the Cr-Mo steel material, while the strength and toughness are secured, the welding cold crack resistance is greatly improved and the reheat crack resistance is improved. In addition, it can also be improved. Pressure vessels, etc. used in high-temperature and high-pressure hydrogen environments such as petrochemical and petroleum refining, and large-diameter thick-walled tubes used under high-temperature and high-pressure in power plant facilities such as boilers. It is extremely effective for
【図1】Ca、S、S.Alの添加量とy割れ試験タイ
プの再熱割れ試験による断面割れ率との関係を示す図。FIG. 1 shows Ca, S, S. The figure which shows the relationship between the amount of addition of Al, and the cross-section cracking rate by the reheat cracking test of a y-cracking test type.
Claims (2)
Si:0.01〜0.8%、Mn:0.05〜1%、
P:≦0.015%、S:≦0.003%、Cu:0.
05〜1%、Ni:0.05〜1%、Cr:2.0〜
3.5%、Mo+1/2W:0.5〜1.5%、V:0.
05〜0.5%、Ti:0.005〜0.05%、B:
0.0003〜0.003%、Al:0.005〜0.
035%、N:≦0.006%、O:≦0.005%、
Ca:0.0005〜0.005%を含有し、かつ0.
5<Cu%+Ni%<1.2,及び1<Ca%/S%<
10の関係を満足し、残部は不可避的不純物及び鉄から
なることを特徴とする耐溶接低温割れ性及び耐再熱割れ
性に優れたCr−Mo鋼。1. C: 0.03 to 0.08% by weight,
Si: 0.01 to 0.8%, Mn: 0.05 to 1%,
P: ≤ 0.015%, S: ≤ 0.003%, Cu: 0.
05-1%, Ni: 0.05-1%, Cr: 2.0-
3.5%, Mo + 1 / 2W: 0.5-1.5%, V: 0.
05-0.5%, Ti: 0.005-0.05%, B:
0.0003 to 0.003%, Al: 0.005 to 0.
035%, N: ≤ 0.006%, O: ≤ 0.005%,
Ca: 0.0005 to 0.005% is contained, and 0.
5 <Cu% + Ni% <1.2, and 1 <Ca% / S% <
Cr-Mo steel satisfying the relationship of 10 and being excellent in weld cold cracking resistance and reheat cracking resistance, characterized in that the balance consists of inevitable impurities and iron.
Si:0.01〜0.8%、Mn:0.05〜1%、
P:≦0.015%、S:≦0.003%、Cu:0.
05〜1%、Ni:0.05〜1%、Cr:2.0〜
3.5%、Mo+1/2W:0.5〜1.5%、V:0.
05〜0.5%、Ti:0.005〜0.03%、B:
0.0003〜0.003%、Al:0.003〜0.
035%、N:≦0.006%、O:≦0.005%、
Ca:0.0005〜0.005%を含有し、更に、N
b:≦0.10%を含有し、かつ0.5<Cu%+Ni
%<1.2,及び1<Ca%/S%<10の関係を満足
し、残部は不可避的不純物及び鉄からなることを特徴と
する耐溶接低温割れ性及耐再熱割れ性に優れたCr−M
o鋼。2. C: 0.03 to 0.08% by weight,
Si: 0.01 to 0.8%, Mn: 0.05 to 1%,
P: ≤ 0.015%, S: ≤ 0.003%, Cu: 0.
05-1%, Ni: 0.05-1%, Cr: 2.0-
3.5%, Mo + 1 / 2W: 0.5-1.5%, V: 0.
05-0.5%, Ti: 0.005-0.03%, B:
0.0003 to 0.003%, Al: 0.003 to 0.
035%, N: ≤ 0.006%, O: ≤ 0.005%,
Ca: 0.0005 to 0.005% is contained, and further N
b: contains ≦ 0.10% and 0.5 <Cu% + Ni
% Welding cold cracking resistance and reheat cracking resistance, which are characterized by satisfying the relationships of% <1.2 and 1 <Ca% / S% <10, and the balance consisting of inevitable impurities and iron. Cr-M
o steel.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11145796A JPH09296249A (en) | 1996-05-02 | 1996-05-02 | Chromium-molybdenum steel |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11145796A JPH09296249A (en) | 1996-05-02 | 1996-05-02 | Chromium-molybdenum steel |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH09296249A true JPH09296249A (en) | 1997-11-18 |
Family
ID=14561724
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP11145796A Pending JPH09296249A (en) | 1996-05-02 | 1996-05-02 | Chromium-molybdenum steel |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH09296249A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2006112428A1 (en) * | 2005-04-18 | 2006-10-26 | Sumitomo Metal Industries, Ltd. | Low alloy steel |
KR100837967B1 (en) * | 2006-04-26 | 2008-06-13 | 가부시키가이샤 고베 세이코쇼 | Weld metal excellent in toughness and sr cracking resistance |
-
1996
- 1996-05-02 JP JP11145796A patent/JPH09296249A/en active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2006112428A1 (en) * | 2005-04-18 | 2006-10-26 | Sumitomo Metal Industries, Ltd. | Low alloy steel |
JPWO2006112428A1 (en) * | 2005-04-18 | 2008-12-11 | 住友金属工業株式会社 | Low alloy steel |
JP4561834B2 (en) * | 2005-04-18 | 2010-10-13 | 住友金属工業株式会社 | Low alloy steel |
KR100837967B1 (en) * | 2006-04-26 | 2008-06-13 | 가부시키가이샤 고베 세이코쇼 | Weld metal excellent in toughness and sr cracking resistance |
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