JPH0625393B2

JPH0625393B2 - Hydrogen resistant low alloy steel for high temperature and high pressure

Info

Publication number: JPH0625393B2
Application number: JP60035929A
Authority: JP
Inventors: 靖男乙黒; 英明伊藤; 俊明斉藤; 勝邦橋本
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1985-02-25
Filing date: 1985-02-25
Publication date: 1994-04-06
Anticipated expiration: 2009-04-06
Also published as: JPS61195955A

Description

【発明の詳細な説明】（産業上の利用分野）本発明は高温高圧下で用いられる化学機器類の構成材料
の鋼材に関するものであり、特に高温高圧水素に対して
優れた抵抗性を有する化学プラント機器構成材料に適し
た高温高圧用耐水素低合金鋼にかかわるものである。TECHNICAL FIELD The present invention relates to a steel material as a constituent material of chemical equipment used under high temperature and high pressure, and particularly to a chemistry having excellent resistance to high temperature and high pressure hydrogen. It relates to hydrogen-resistant low-alloy steel for high-temperature and high-pressure, which is suitable for constituent materials of plant equipment.

（従来の技術および問題点）近年化学工業の発展はめざましく、石油化学精製、重質
油分解プロセスなど高温高圧水素雰囲気で使用される機
器は広範囲にわたり、そのプロセスも高温高圧化並びに
大型化の傾向があり、使用条件は苛酷なものになつてい
る。したがつて、その構成材料の選択に際しては耐水素
性を十分考慮する必要がある。(Prior art and problems) In recent years, the development of the chemical industry has been remarkable, and a wide range of equipment is used in high-temperature and high-pressure hydrogen atmospheres such as petrochemical refining and heavy oil cracking processes. However, the usage conditions are becoming severe. Therefore, it is necessary to fully consider the hydrogen resistance when selecting the constituent material.

特に溶接部の耐水素性は母材と比較して劣つており、十
分な対策が必要である。このような現状から、高温高圧
水素雰囲気中で脆化が生じ難く、耐水素性の高い低合金
鋼の開発が昨今特に要望されて来ている。In particular, the hydrogen resistance of the weld is inferior to that of the base metal, and sufficient measures are required. Under these circumstances, there has recently been a particular demand for the development of low-alloy steel that is resistant to embrittlement in a high-temperature high-pressure hydrogen atmosphere and has high hydrogen resistance.

そこで、従来かかる要望に応えるべく既に幾つかの提案
がなされており、例えば特公昭５０−７５２８号公報、
特公昭５７−１０９４７号公報等に記載の技術が知られ
ている。すなわち、これらの技術はいずれも鋼中に炭化
物生成元素を添加してＣの固定を計るものである。水素
脆化は、鋼中Ｃが外部の水素雰囲気から侵入拡散して来
る水素と反応してメタンガスを生成し、このメタンガス
の圧力が極めて高いために割れが発生することに起因す
るものと考えられ、したがつてＣを炭化物として固定す
ればかかるメタン反応によるガス生成反応は抑制できる
と言える。Therefore, some proposals have already been made in order to meet such a demand, for example, Japanese Patent Publication No. 50-7528.
The technique described in Japanese Patent Publication No. 57-10947 is known. That is, all of these techniques measure the fixation of C by adding a carbide-forming element to steel. Hydrogen embrittlement is considered to be due to the fact that C in steel reacts with hydrogen that has entered and diffused from the outside hydrogen atmosphere to generate methane gas, and cracks occur because the pressure of this methane gas is extremely high. Therefore, it can be said that if C is fixed as a carbide, the gas generation reaction by the methane reaction can be suppressed.

しかしながらこの手段は、Ｃを固定するためにはＷ、T
i、Zr、Nb、Ｖのような強炭化物生成元素を多量に添加
する必要があるという問題点がある。However, this means is to fix C, W, T
There is a problem that it is necessary to add a large amount of a strong carbide forming element such as i, Zr, Nb and V.

また、鋼中Ｃが外部の水素雰囲気から拡散して来る水素
と反応してメタンガスを生成する反応を少なくするには
鋼中Ｃを少なくすることも考えられるが、強度が低下す
るという欠点がある。Further, in order to reduce the reaction in which C in steel reacts with hydrogen diffused from the outside hydrogen atmosphere to generate methane gas, it is conceivable to reduce C in steel, but there is a drawback that strength is lowered. .

そこで、本発明者らの一部は先に低炭化または炭化物生
成手段のほかに耐水素性を鋼に付与する新規な手段につ
いて検討した。その結果、そもそもメタン生成反応は固
溶Ｃおよび炭化物Ｃと水素との反応であるので、メタン
生成反応が活発化するのはＣの活量が大なるときであ
り、Ｃの活量を増大させる元素の量を減らすかあるいは
Ｃの活量を減少させる元素を添加すれば良いという結論
に達し、かかる元素の一つとしてSiを減少させるという
新規な提案を特開昭５９−６３５７号公報により行なつ
ている。Therefore, some of the inventors of the present invention previously investigated a new means for imparting hydrogen resistance to steel in addition to the low carbonization or carbide generation means. As a result, since the methanogenic reaction is a reaction of solid solution C and carbide C with hydrogen, the methanogenic reaction is activated when the activity of C becomes large and the activity of C is increased. We have come to the conclusion that it is only necessary to add an element that reduces the amount of element or that reduces the activity of C, and a new proposal to reduce Si as one of such elements is made in JP-A-59-6357. I'm running.

しかしながら、かかる技術においてもＣの活量を減少さ
せる元素を積極的に添加する点については未検討であ
り、この点においてさらに検討を進める必要があつた。However, even in such a technique, the point of positively adding an element that reduces the activity of C has not been studied, and it is necessary to further study in this respect.

そこで、本発明者らはその後もＣの活量を減少させる元
素について、すなわち耐水素性付与効果の大なる元素に
ついて検討を行なつた結果、特にMo系低合金鋼において
Si量を下げなくてもREM およびCaがかかる目的に最もか
なつた顕著な効果を示すという全く新規な知見を得るに
至つた。Therefore, the inventors of the present invention continued to study elements that reduce the activity of C, that is, elements that have a large effect of imparting hydrogen resistance, and as a result, particularly in Mo-based low alloy steels.
We have obtained a completely new finding that REM and Ca show the most outstanding effect for this purpose without lowering the Si content.

すなわち、本発明者らは耐水素性の実験を行なうために
第１表に示す成分範囲の各種試作鋼を溶製し、これから
寸法１２mmφ×６５mmの試験片を切り出し、熱サイクル
再現装置により溶接熱影響部を再現した試料を用いて高
温高圧水素中で促進試験を行なつた。第１表に試験条件
および結果を併記した。That is, the inventors of the present invention melted various trial steels having the compositional ranges shown in Table 1 in order to carry out an experiment of hydrogen resistance, cut out a test piece having a size of 12 mmφ × 65 mm from this, and used a heat cycle reproduction device to analyze the welding heat effect. Accelerated tests were carried out in high-temperature high-pressure hydrogen using a sample in which the parts were reproduced. The test conditions and the results are shown in Table 1.

促進試験の結果からその脆化度(％)とREM ，Caの関係を
示したのが第５図である。この場合、REM およびCa同時
添加鋼は図中のREM ％あるいはCa％の大きい方を表示し
た。なお脆化度とはで表わすものであり、ここにφ_Oは水素処理前の絞り
値、φは水素処理後の絞り値である。しかして、この式
は脆化度が大きいほど水素に対する抵抗性が小さいこと
を示している。 Fig. 5 shows the relationship between the degree of embrittlement (%) and REM and Ca from the results of the acceleration test. In this case, for REM and Ca simultaneous addition steel, the one with the larger REM% or Ca% in the figure is displayed. What is the degree of brittleness? Where φ _O is the aperture value before hydrogen treatment and φ is the aperture value after hydrogen treatment. Thus, this equation shows that the larger the degree of embrittlement, the smaller the resistance to hydrogen.

実験結果から明らかなように、Mo系の低合金鋼において
はＣの活量増大元素であるSiを減らすことなく、Ｃの活
量抑制元素であるREM 、Caの単独または複合添加により
Ｃの活量が減少し、これによつてメタン生成反応が抑制
される結果、高温高圧水素雰囲気中での鋼材の水素脆化
が防止できるという従来全く例を見なかつた技術思想に
基いて本発明がなされたのである。As is clear from the experimental results, in the Mo-based low alloy steel, the activity of C can be increased by adding REM and Ca, which are the activity suppressing elements of C, alone or in combination without reducing Si, which is the activity increasing element of C. The present invention has been made based on the technical idea that the hydrogen embrittlement of a steel material in a high-temperature high-pressure hydrogen atmosphere can be prevented as a result of the decrease in the amount and the suppression of the methane production reaction by this. It was.

（問題点を解決するための手段、作用）本発明の要旨は、重量％でＣ：0.05〜0.25％、Si：0.01
5〜0.70％、Mn：0.2〜1.5％、Mo：0.3〜1.5％を含有
し、REM ：0.01〜0.10％およびCa：0.001〜0.010％の一
方または両方を含有し、かつSiとREM との関係は第１図
ＡＢＣＤＥに囲まれる範囲、SiとCaとの関係は第２図Ａ
ＢＣＤＥに囲まれる範囲、またSi，REM およびCa三者の
関係は第３図ＡＢＣＤＥＦＧＨＩＪに囲まれる範囲をお
のおの満足し、さらに第４図ＡＢＣＤＥに囲まれる範囲
のSolAlとＮを含有し、残部Feおよび不可避的不純物か
らなることを特徴とする高温高圧用耐水素低合金鋼にあ
る。(Means and Actions for Solving Problems) The gist of the present invention is that C: 0.05 to 0.25% and Si: 0.01% by weight.
5 to 0.70%, Mn: 0.2 to 1.5%, Mo: 0.3 to 1.5%, REM: 0.01 to 0.10% and Ca: 0.001 to 0.010%, or both, and the relationship between Si and REM Is the range surrounded by ABCDE in Fig. 1, and the relationship between Si and Ca is in Fig. 2A.
The range surrounded by BCDE, and the three-way relationship between Si, REM and Ca, each satisfy the range surrounded by ABCDEFGHIJ in FIG. 3, and further contains SolAl and N in the range surrounded by ABCDE in FIG. It is a hydrogen-resistant low-alloy steel for high temperature and high pressure, which is characterized by comprising unavoidable impurities.

ただし第１図においてSi％、REM ％はＡ（0.015，0.01），Ｂ（0.10，0.01），Ｃ（0.70，0.0
3），Ｄ（0.70，0.10），Ｅ（0.015，0.10）第２図においてSi％、Ca％はＡ（0.015，0.001），Ｂ（0.10，0.001），Ｃ（0.70，
0.007），Ｄ（0.70，0.010），Ｅ（0.015，0.010），第３図においてSi％、REM ％、Ca％はＡ（0.015，0.01，0.001），Ｂ（0.015，0.01，0.010）
Ｃ（0.015，0.10，0.010），Ｄ（0.015，0.10，0.001）
Ｅ（0.70，0.10，0.001），Ｆ（0.70，0.10，0.010），
Ｇ（0.70，0.01，0.010），Ｈ（0.70，0.01，0.007）Ｉ
（0.70，0.03，0.001），Ｊ（0.10，0.01，0.001）第４図においてSolAl％、Ｎ％はＡ（0.010，0.003），Ｂ（0.010，0.005），Ｃ（0.01
6，0.008），Ｄ（0.06，0.008），Ｅ（0.06，0.003）で
ある。However, in Fig. 1, Si% and REM% are A (0.015, 0.01), B (0.10, 0.01), C (0.70, 0.0).
3), D (0.70, 0.10), E (0.015, 0.10) In Fig. 2, Si% and Ca% are A (0.015, 0.001), B (0.10, 0.001), C (0.70,
0.007), D (0.70, 0.010), E (0.015, 0.010), Si%, REM%, Ca% in Fig. 3 are A (0.015, 0.01, 0.001), B (0.015, 0.01, 0.010)
C (0.015, 0.10, 0.010), D (0.015, 0.10, 0.001)
E (0.70, 0.10, 0.001), F (0.70, 0.10, 0.010),
G (0.70, 0.01, 0.010), H (0.70, 0.01, 0.007) I
(0.70, 0.03, 0.001), J (0.10, 0.01, 0.001) SolAl% and N% in Fig. 4 are A (0.010, 0.003), B (0.010, 0.005), C (0.01
6, 0.008), D (0.06, 0.008), E (0.06, 0.003).

以下、本発明を詳細に説明する。Hereinafter, the present invention will be described in detail.

まず、Ｃは焼き入れ性と強度を高めるために少なくとも
0.05％以上必要とし、また多量になると靭性、溶接性を
害することと耐水素性に対する悪影響を考慮してその上
限を0.25％とした。First, C is at least to improve hardenability and strength.
The upper limit is set to 0.25% in consideration of the need for 0.05% or more, and the adverse effects on hydrogen resistance and toughness and weldability when a large amount is used.

次に、Siは脱酸剤として少なくとも0.015％必要であ
り、また引張り強さを増大させる効果があるが、多量に
含有すると靭性を害するのでその上限を0.70％に限定し
た。Next, Si needs to be at least 0.015% as a deoxidizing agent and has an effect of increasing the tensile strength, but if contained in a large amount, it impairs toughness, so the upper limit was set to 0.70%.

また、Mnは脱酸元素として使われているが、焼き入れ性
を増し、強度および靭性を高める元素である。しかし、
0.2％未満ではその効果が十分でなく、1.5％を超えると
耐水素性を減ずるので、その範囲は0.2〜1.5％が効果的
である。Mn, which is used as a deoxidizing element, is an element that enhances hardenability and strength and toughness. But,
If it is less than 0.2%, the effect is not sufficient, and if it exceeds 1.5%, the hydrogen resistance is reduced, so that the range is 0.2 to 1.5%.

さらに、Moは高温強度を高め、かつ耐水素性を向上させ
るために0.3％以上必要である。しかし、1.5％を超える
添加は靭性を低下させるために、その範囲を0.3〜1.5％
とした。Further, Mo is required to be 0.3% or more in order to increase high temperature strength and hydrogen resistance. However, addition of more than 1.5% lowers toughness, so the range is 0.3-1.5%.
And

さらに、本発明においてはＣの活量を減少させるため、
すなわち耐水素性付与効果を大とする理由でREM および
Caの一方または両方を添加する。Further, in the present invention, since the activity of C is decreased,
In other words, REM and
One or both of Ca is added.

まず、REM は原子番号５７〜７１の希土類元素の１種ま
たは２種以上であつて、REM ：0.01〜0.10％含有する。
これはＣの活量を抑制する効果があるが、0.01％未満で
は効果がなく、0.10％を超えると応力除去焼鈍後の靭性
が低下するため、その範囲を0.01〜0.10％とした。First, REM is one or more kinds of rare earth elements having atomic numbers of 57 to 71 and contains REM: 0.01 to 0.10%.
This has the effect of suppressing the activity of C, but if it is less than 0.01%, it has no effect, and if it exceeds 0.10%, the toughness after stress relief annealing decreases, so the range was made 0.01 to 0.10%.

また、Caは0.001〜0.010％含有するものであり、REM 同
様にＣの活量を抑制する効果がある。0.001％未満では
その効果がなく、0.010％を超えると応力除去焼鈍後の
靭性が低下すると同時にMo系低合金鋼に固溶させること
は困難となるため、その範囲を0.001〜0.010％とした。Further, Ca is contained in an amount of 0.001 to 0.010% and has an effect of suppressing the activity of C similarly to REM. If it is less than 0.001%, there is no effect, and if it exceeds 0.010%, the toughness after stress relief annealing decreases, and it becomes difficult to form a solid solution in a Mo-based low alloy steel, so the range was made 0.001 to 0.010%.

本発明においては、REM およびCaの一方または両方を含
有するにあたり、Ｃの活量を減少させるため、すなわち
耐水素性付与効果を大とする日的としてSiとの関連にお
いてREM およびCaの含有量を規定したところに重要な骨
子がある。すなわち、REM またはCaのいずれか一方を含
有する場合には、SiとREM またはCaとの関係が第１図ま
たは第２図のおのおのＡＢＣＤＥに囲まれる範囲を満足
し、さらにREM およびCaの両方を含有する場合にはSi，
REM およびCa三者の関係が第３図ＡＢＣＤＥＦＧＨＩＪ
に囲まれる範囲を満足しなければならない。ただし、第
１図においては、Ａ，Ｂ，Ｃ，Ｄ，Ｅの各座標点はSi
％、REM ％がＡ（0.015，0.01）、Ｂ（0.10，0.01）、Ｃ（0.70，0.0
3）Ｄ（0.70，0.10）Ｅ（0.015，0.10）であり、第２図
においてはＡ，Ｂ，Ｃ，Ｄ，Ｅの各座標点はSi％、Ca％
がＡ（0.015，0.001）、Ｂ（0.10，0.001），Ｃ（0.7
0，0.007）、Ｄ（0.70，0.010）、Ｅ（0.015，0.010）
であり、第３図においてはＡ，Ｂ，Ｃ，Ｄ，Ｅ，Ｆ，
Ｇ，Ｈ，Ｉ，Ｊの各座標点はSi％、REM ％、Ca％がＡ
（0.015，0.01，0.001）、Ｂ（0.015，0.01，0.010）、
Ｃ（0.015，0.10，0.010），Ｄ（0.015，0.10，0.00
1），Ｅ（0.70，0.10，0.001），Ｆ（0.70，0.10，0.01
0），Ｇ（0.70，0.01，0.010）Ｈ（0.70，0.01，0.00
7），Ｉ（0.70，0.03，0.001），Ｊ（0.10，0.01，0.00
1）である。In the present invention, when one or both of REM and Ca are contained, the content of REM and Ca in relation to Si is reduced in order to reduce the activity of C, that is, as a day to maximize the hydrogen resistance imparting effect. There is an important skeleton in the prescribed place. That is, when either REM or Ca is contained, the relationship between Si and REM or Ca satisfies the range surrounded by ABCDE in each of FIG. 1 and FIG. If contained, Si,
The relationship between REM and Ca is shown in Fig. 3. ABCDEFGHIJ
Must satisfy the range surrounded by. However, in FIG. 1, the coordinate points A, B, C, D, and E are Si.
%, REM% is A (0.015, 0.01), B (0.10, 0.01), C (0.70, 0.0)
3) D (0.70, 0.10) E (0.015, 0.10), and in FIG. 2, the coordinate points A, B, C, D and E are Si% and Ca%.
Is A (0.015, 0.001), B (0.10, 0.001), C (0.7
0, 0.007), D (0.70, 0.010), E (0.015, 0.010)
And in FIG. 3, A, B, C, D, E, F,
For each coordinate point of G, H, I and J, Si%, REM% and Ca% are A
(0.015, 0.01, 0.001), B (0.015, 0.01, 0.010),
C (0.015, 0.10, 0.010), D (0.015, 0.10, 0.00)
1), E (0.70, 0.10, 0.001), F (0.70, 0.10, 0.01)
0), G (0.70, 0.01, 0.010) H (0.70, 0.01, 0.00)
7), I (0.70, 0.03, 0.001), J (0.10, 0.01, 0.00)
1).

まず、SiとREM との関係については、Ｃの活量を減少さ
せるため、すなわち耐水素性付与効果を大とさせる検討
の結果、第１図のごとき関係を得た。同図中線ＡＢはRE
M の下限0.01％を、線ＥＤはREM の上限0.10％をおのお
の示し、また線ＡＥはSiの下限0.015％を、線ＣＤはSi
の上限0.70％をおのおの示す。斜線ＢＣはＣの活量を増
大させる、すなわち耐水素性付与効果を小とするSiの含
有量に対して、REM によるＣの活量を減少させる、すな
わち耐水素性付与効果を大とさせるに必要な含有量の平
衡関係を示す。First, regarding the relationship between Si and REM, as a result of examination to reduce the activity of C, that is, to enhance the hydrogen resistance imparting effect, the relationship as shown in FIG. 1 was obtained. In the figure, line AB is RE
The lower limit of M is 0.01%, the line ED shows the upper limit of REM 0.10%, the line AE shows the lower limit of Si 0.015%, and the line CD shows Si.
The upper limit of 0.70% is shown for each. The hatched line BC is necessary to increase the activity of C, that is, to reduce the activity of C due to REM, that is, to increase the effect of imparting hydrogen resistance, with respect to the Si content that reduces the effect of imparting hydrogen resistance. The equilibrium relationship of content is shown.

次に、SiとCaとの関係については、Ｃの活量を減少させ
るため、すなわち耐水素性付与効果を大とさせる検討の
結果、第２図のごとき関係を得た。同図中線ＡＢはCaの
下限0.001％を、線ＥＤはCaの上限0.010％をおのおの示
し、また線ＡＥはSiの下限0.015％を、線ＣＤはSiの上
限0.70％をおのおの示す。斜線ＢＣはＣの活量を増大さ
せる、すなわち耐水素性付与効果を小とするSiの含有量
に対して、CaによるＣの活量を減少させる、すなわち耐
水素性付与効果を大とさせるに必要な含有量の平衡関係
を示す。Next, regarding the relationship between Si and Ca, as a result of a study for reducing the activity of C, that is, for enhancing the hydrogen resistance imparting effect, the relationship as shown in FIG. 2 was obtained. In the figure, the line AB indicates the lower limit of Ca of 0.001%, the line ED indicates the upper limit of Ca of 0.010%, the line AE indicates the lower limit of Si of 0.015%, and the line CD indicates the upper limit of Si of 0.70%. The shaded line BC is necessary to increase the activity of C, that is, to reduce the activity of C due to Ca, that is, to increase the effect of imparting hydrogen resistance with respect to the content of Si that reduces the effect of imparting hydrogen resistance. The equilibrium relationship of content is shown.

さらに、REM およびCaの両方を複合添加した場合につい
ては、Siとの関係が第３図のＡＢＣＤＥＦＧＨＩＪの範
囲内にあることが必要である。同図中平面ＡＢＧＨＪは
REM の下限0.01％を、平面ＣＤＥＦはREM の上限0.10％
をおのおの示し、また平面ＡＤＥＩＪＢはCaの下限0.00
1％を、平面ＢＣＦＧはCaの上限0.010％をおのおの示
し、さらに平面ＡＢＣＤはSiの下限0.015％を、平面Ｅ
ＦＧＨＩはSiの上限0.70％をおのおの示す。平面ＨＩＪ
はＣの活量を増大させる、すなわち耐水素性付与効果を
小とするSiの含有量に対して、REM 、CaによるＣの活量
を減少させる、すなわち耐水素性付与効果を大とさせる
に必要な含有量の平衡関係を示す。Furthermore, in the case of adding both REM and Ca in combination, the relationship with Si must be within the range ABCDEFGHIJ in FIG. The plane ABGHJ in the figure is
The lower limit of REM is 0.01%, and the upper limit of REM is 0.10% for planar CDEF.
, And the plane ADEIJB is the lower limit of Ca of 0.00
1%, plane BCFG shows the upper limit of Ca of 0.010%, and plane ABCD shows the lower limit of 0.015% of Si.
FGHI shows the upper limit of Si of 0.70%. Plane HIJ
Is necessary to increase the activity of C, that is, to reduce the activity of C due to REM and Ca, that is, to increase the effect of imparting hydrogen resistance with respect to the content of Si that reduces the effect of imparting hydrogen resistance. The equilibrium relationship of content is shown.

また、本発明においては前記のごとくSiとREM ，Caの一
方または両方との関係の規定に加えて、SolAlとＮとの
関係を第４図ＡＢＣＤＥに囲まれる範囲に規定すること
によつて前記成分系の鋼におけるγ粒の粒度を制御し、
これによつて耐水素性および靭性を向上せしめることを
計つている。すなわち、第４図の関係は、高温高圧用耐
水素低合金鋼としてＣ：0.05〜0.25％、Si：0.015〜0.7
0％、Mn：0.2〜1.5％、Mo：0.3〜1.5％、それにREM ：
0.01〜0.10％、Ca：0.001〜0.010％の一方または両方を
含有させた鋼に種々SolAl およびＮを変化せしめて添加
して検討した結果得られたものである。In the present invention, in addition to the definition of the relationship between Si and one or both of REM and Ca as described above, the relationship between SolAl and N is defined within the range surrounded by ABCDE in FIG. Controls the grain size of γ grains in the component steel,
This is intended to improve hydrogen resistance and toughness. That is, the relationship of FIG. 4 is as follows: C: 0.05-0.25%, Si: 0.015-0.7 as hydrogen-resistant low alloy steel for high temperature and high pressure.
0%, Mn: 0.2-1.5%, Mo: 0.3-1.5%, and REM:
It was obtained as a result of examination by adding various SolAl and N while changing them to steel containing one or both of 0.01 to 0.10% and Ca: 0.001 to 0.010%.

同図中線ＡＢはSolAlの下限0.01％を、線ＤＥはSolAl
の上限0.06％を示す。SolAlが0.01％未満ではγ粒が粗
大化するため焼きもどし脆化を起しやすく、また脆化度
が大きくなり、さらに靭性が低下する。また0.06％を超
えるとγ粒は混粒となり、靭性が低下する。また、線Ａ
ＥはＮの下限0.003％を、線ＣＤはＮの上限0.008％を示
す。Ｎが0.003％未満ではγ粒が粗大化するため焼きも
どし脆化を起しやすく、また脆化度が大きくなり、さら
に靭性が低下する。また0.008％を超えるとγ粒は微細
化し、靭性、焼き入れ性および強度が低下する。In the figure, the line AB indicates the lower limit of 0.01% for SolAl, and the line DE indicates SolAl.
Indicates an upper limit of 0.06%. If the content of SolAl is less than 0.01%, the γ grains are coarsened, so that tempering embrittlement easily occurs, the degree of embrittlement increases, and the toughness further decreases. On the other hand, if it exceeds 0.06%, the γ grains become mixed grains, and the toughness decreases. Also, line A
E indicates a lower limit of N of 0.003%, and line CD indicates an upper limit of N of 0.008%. If N is less than 0.003%, the γ grains become coarse, so that tempering embrittlement easily occurs, and the degree of embrittlement increases, and the toughness further decreases. On the other hand, if it exceeds 0.008%, the γ grains become finer, and the toughness, hardenability and strength deteriorate.

さらに、線ＢＣはSolAl とＮの量が化学量論的に１：１
の関係を示す。SolAl とＮとの関係は、この線より上側
においてはγ粒が微細化し、靭性、焼き入れ性および強
度が低下する。Furthermore, the line BC shows that the amount of SolAl and N is stoichiometrically 1: 1.
Shows the relationship. Regarding the relationship between SolAl and N, γ grains become finer above this line, and the toughness, hardenability and strength decrease.

次に、本発明の効果を実施例によりさらに詳細に述べ
る。Next, the effects of the present invention will be described in more detail by way of examples.

（実施例）第２表に供試材の化学成分を示した。NO.１，３，５，
７，９，10，11，12，13，14は本発明に係る鋼、NO.
２，４，６，８，15は比較鋼である。(Example) Table 2 shows the chemical composition of the test material. NO.1, 3, 5,
7, 9, 10, 11, 12, 13, 14 are steels according to the present invention, NO.
2, 4, 6, 8 and 15 are comparative steels.

供試材の耐水素性を比較するため、溶接熱影響部を再現
した試料を用いて高温高圧水素雰囲気中で１００時間加
熱した後の引張り特性を第２表に合わせて示した。その
結果、本発明鋼はこの高温高圧水素処理において水素脆
化せず、比較鋼に比べて著しく高い特性を示すが、比較
鋼は高温高圧水素処理によつて引張り強さが低下し、か
つ絞りが著しく低下していることが分る。In order to compare the hydrogen resistance of the test materials, the tensile properties after heating for 100 hours in a high-temperature high-pressure hydrogen atmosphere using a sample in which the weld heat affected zone was reproduced are also shown in Table 2. As a result, the steel of the present invention does not undergo hydrogen embrittlement in this high-temperature high-pressure hydrogen treatment, and exhibits significantly higher properties than the comparative steel, but the comparative steel has a reduced tensile strength due to the high-temperature high-pressure hydrogen treatment, and has a reduced drawing It can be seen that is significantly reduced.

（発明の効果）以上のとおり、本発明のMo系低合金鋼は高温高圧下水素
雰囲気中において水素脆化が有利に防止でき、かつ強度
低下のない優れた性質を有し、その工業的価値は極めて
大きいものである。 (Effects of the Invention) As described above, the Mo-based low alloy steel of the present invention has excellent properties in which hydrogen embrittlement can be advantageously prevented in a hydrogen atmosphere under high temperature and high pressure, and strength does not decrease, and its industrial value Is extremely large.

【図面の簡単な説明】第１図は本発明におけるSiとREM との関係の適正範囲を
示す図、第２図は本発明におけるSiとCaとの関係の適正
範囲を示す図、第３図は本発明におけるSiとREM とCaと
の関係の適正範囲を示す図、第４図は本発明におけるSo
lAlとＮとの関係の適正範囲を示す図、第５図はREM お
よびCaと脆化度との関係を示す図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an appropriate range of the relationship between Si and REM in the present invention, FIG. 2 is a diagram showing an appropriate range of the relationship between Si and Ca in the present invention, and FIG. Is a diagram showing an appropriate range of the relationship between Si, REM, and Ca in the present invention, and FIG. 4 is a diagram showing So in the present invention.
FIG. 5 is a diagram showing an appropriate range of the relation between lAl and N, and FIG. 5 is a diagram showing the relation between REM and Ca and the degree of embrittlement.

───────────────────────────────────────────────────── フロントページの続き (72)発明者橋本勝邦神奈川県相模原市淵野辺５−10―１新日本製鐵株式会社第二技術研究所内 (56)参考文献特開昭58−1059（ＪＰ，Ａ) 特開昭57−73162（ＪＰ，Ａ) 特開昭55−38901（ＪＰ，Ａ) 特開昭54−31020（ＪＰ，Ａ) 特公昭57−10947（ＪＰ，Ｂ２) 特公昭50−7528（ＪＰ，Ｂ２) ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsukuni Hashimoto 5-10-1 Fuchinobe, Sagamihara-shi, Kanagawa Nippon Steel Corporation Second Technical Research Institute (56) Reference JP-A-58-1059 (JP , A) JP 57-73162 (JP, A) JP 55-38901 (JP, A) JP 54-31020 (JP, A) JP 57-10947 (JP, B2) JP 50-7528 (JP, B2)

Claims

[Claims]

1. By weight%, C: 0.05 to 0.25%, Si: 0.015 to 0.70%, Mn: 0.2 to 1.5%, Mo: 0.3 to 1.5. %, REM: 0.01 to 0.10% and Ca: 0.00
1 to 0.010% of one or both, and the relationship between Si and REM is the range surrounded by ABCDE in FIG. 1, the relationship between Si and Ca is the range surrounded by ABCDE in FIG.
The relationship between Ca and Ca satisfies each range surrounded by ABCDEFGHIJ in Fig. 3, and further, in Fig. 4 ABCDE
A hydrogen-resistant low-alloy steel for high-temperature and high-pressure use, characterized by containing SolAl and N in the range surrounded by, and the balance Fe and unavoidable impurities. However, in Fig. 1, Si% and REM% are A (0.015, 0.01), B (0.10, 0.01), C (0.70, 0.0).
3), D (0.70, 0.10), E (0.015, 0.10), Si% and Ca% in Fig. 2 are A (0.015, 0.001), B (0.10, 0.001), C (0.70,
0.007), D (0.70, 0.010), E (0.015, 0.010), Si%, REM%, Ca% in Fig. 3 are A (0.015, 0.01, 0.001), B (0.015, 0.01, 0.01)
0), C (0.015, 0.10, 0.010), D (0.015, 0.10, 0.
001), E (0.70, 0.10, 0.001), F (0.70, 0.10, 0.
010), G (0.70, 0.01, 0.010), H (0.70, 0.01, 0.
007), I (0.70, 0.03, 0.001), J (0.10, 0.01, 0.
001), SolAl% and N% in Fig. 4 are A (0.010, 0.003), B (0.010, 0.005), C (0.01
6, 0.008), D (0.06, 0.008), E (0.06, 0.003).