JPH049847B2 - - Google Patents
Info
- Publication number
- JPH049847B2 JPH049847B2 JP60168619A JP16861985A JPH049847B2 JP H049847 B2 JPH049847 B2 JP H049847B2 JP 60168619 A JP60168619 A JP 60168619A JP 16861985 A JP16861985 A JP 16861985A JP H049847 B2 JPH049847 B2 JP H049847B2
- Authority
- JP
- Japan
- Prior art keywords
- prior austenite
- austenite grain
- steel
- less
- tempering
- 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.)
- Expired - Lifetime
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 57
- 239000010959 steel Substances 0.000 claims description 57
- 229910001566 austenite Inorganic materials 0.000 claims description 40
- 238000010791 quenching Methods 0.000 claims description 21
- 230000000171 quenching effect Effects 0.000 claims description 20
- 238000005496 tempering Methods 0.000 claims description 20
- 238000005096 rolling process Methods 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 17
- 230000009466 transformation Effects 0.000 claims description 14
- 238000004519 manufacturing process Methods 0.000 claims description 13
- 229910000734 martensite Inorganic materials 0.000 claims description 9
- 239000012535 impurity Substances 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 239000000463 material Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000001953 recrystallisation Methods 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- 229910000851 Alloy steel Inorganic materials 0.000 description 2
- 229910006639 Si—Mn Inorganic materials 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 229910006295 Si—Mo Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 239000012047 saturated solution Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Description
（産業上の利用分野）
本発明は直接焼入れ焼戻しによる耐硫化物応力
腐食割れ特性（以下耐SSCC特性と称す）の優れ
た鋼を製造する方法に関するものである。
（従来の技術とその問題点）
近年、サワーガス、サワーオイルのガス田、油
田が多く開発されるようになり、これに伴つて耐
SSCC特性の優れた油井管用鋼材が求められてい
る。
降伏強度50〜80Kg／mm2級のこの種鋼材として、
従来では、Ｃ−Si−Mn鋼もしくはＣ−Si−Mn−
Cr−Mo鋼を焼入れ焼戻し処理することにより製
造されているが、これらの鋼材は、現在において
も次のような問題があつた。
Ｃ−Si−Mo鋼では、降伏強度60〜80Kg／mm2
級の高強度鋼において充分な耐SSCC特性が得
られていない。
Ｃ−Si−Mn−Cr−Mo鋼はＣ−Si−Mn鋼よ
り高い耐SSCC特性が得られているが、添加
Cr、Mo量が多いため、製造コスト高となるの
を避けられない。
サワーガス、サワーオイルにおける腐食環境
条件はますます厳しくなりつつあり、Ｃ−Si−
Mn−Cr−Mo鋼においてもより高い耐SSCC特
性が求められているが、これに十分に答えるこ
とができない。
（問題点を解決するための手段）
本発明は上記のような実情から研究を重ねて創
案されたもので、その目的とするところは、低合
金鋼の範囲において、直接焼入れプロセスによる
組織制御を利用して従来と同強度水準を確保しつ
つしかもより優れた耐SSCC特性を持つ鋼を提供
することにある。
この目的を達成するため、本発明は所定成分の
鋼を熱間加工後、直接焼入れ焼戻しした焼戻しマ
ルテンサイト組織の旧オーステナイト粒展伸度に
着目しこれを規定したもので、すなわち、Ｃ：
0.15〜0.35wt％、Si：0.01〜0.50wt％、Mn：0.4
〜2.0wt％、SolAl：0.001〜0.10wt％の基本組成
を有し、残部Feおよび不可避的不純物からなる
鋼をAc3変態点以上で熱間加工後直接焼入れし、
その後Ac1変態点以下で焼戻しすることによつて
得られる焼戻しマルテンサイト組織において、Ｒ
＝（圧延方向の旧オーステナイト粒径dL）／（肉
厚方向の旧オーステナイト粒径dZ）によつて示さ
れる旧オーステナイト粒展伸度を２以上とするこ
とを特徴とするものである。
以上の鋼の製造方法のうち該鋼の組成について
は、上記基本組成の他、1wt％以下のCu、1wt％
以下のNiのうち１種又は２種を含んだり、2wt％
以下のCr、2wt％以下のMo、0.2wt％以下のＶの
うち１種又は２種を含んだり、0.1wt％以下の
Nb、0.1wt％以下のTiのうち１種又は２種を含
有したり、0.1wt％以下のREM、0.1wt％以下の
Caのうち１種又は２種を含有したり、或いはこ
れらを組合せて複合添加する場合に、各種特性の
より優れたものが得られることになる。
以下本発明を詳述する。
まず本発明者らは、耐SSCC特性を向上させる
治金的因子の一つとして、結晶粒（焼入れ焼戻し
処理を受けた低合金鋼の場合旧オーステナイト
粒）の形状に注目した。そして、旧オーステナイ
ト粒の形状の耐SSCC特性に及ぼす影響を見るた
め、熱間加工条件を変化させることにより旧オー
ステナイト粒形状を制御できる直接焼入れ−焼戻
し処理を施した鋼材の耐SSCC特性について検討
した。
第１図は0.21C−0.22Si−1.32Mn鋼（YS＝74〜
76Kg／mm2）について、圧延仕上り後15秒後直接焼
入れを行つた場合の耐SSCC特性に及ぼす未再結
晶温度領域の圧下率を示すものである。
この第１図から明らかなように、直接焼入れ焼
戻し条件において、未再結晶温度領域の圧下率を
30％以上とすると、旧オーステナイト粒径の展伸
度Ｒ（圧延方向の旧オーステナイト粒径dL／肉厚
方向の旧オーステナイト粒径dZ）が２以上とな
り、この領域で耐SSCC特性（この場合、0.5％酢
酸のH2S飽和溶液中の三点曲げ試験における割れ
発生限界応力Sc値）が向上している。
一方、未再結晶域圧下率を30％未満にすると、
旧オーステナイト粒径の展伸度が２未満となり、
Sc値の向上は余り大きくない。
本発明はこの知見に基づくもので、旧オーステ
ナイト粒の展伸化により耐SSCC特性の改善され
るのは、鋼材表面で発生した割れの肉厚方向への
伝播が圧延方向に展伸した旧オーステナイト粒界
に沿つてそらされやすいことに帰因してしてお
り、旧オーステナイト展伸度Ｒが２未満では耐
SSCC特性の向上に有効でない。
しかして、耐SSCC特性向上に有効な旧オース
テナイト粒の展伸は、微量のNbやTiの添加によ
つて促進される。第２図は0.2C−0.2Si−1.3Mn−
Nb鋼（YS＝74〜76Kg／mm2）において、Nb添加
の影響を検討した結果を示すもので、耐SSCC特
性は、同一の熱間圧延−直接焼入れ焼戻し条件に
おいても、微量Nb添加により顕著に改善されて
いる。
すなわち、Nb無添加鋼では、圧延条件（900
℃以下の圧下率70％、圧延仕上り温度870℃）の
ときだけ展伸度Ｒ＞２となり、圧延条件（1000
℃以下の圧下率70％、圧延仕上り温度920℃）で
はＲ＜２となる。これに対し、Nb添加鋼では、
両圧延条件ともＲ＞２となり、そのような条件に
おいて耐SSCC特性はいずれも顕著に改善される
ことがわかる。
このような旧オーストナイト粒の展伸化による
耐SSCC特性の改善効果は、後述する実施例に示
すように、Ｃ−Si−Mn−Cr−Mo鋼（例えば、
0.3C−0.2Si−0.5Mn−1Cr−0.5Mo鋼）において
も得られることはもとよりである。
以上のような点から、本発明は先に述べたよう
な構成を採用したもので、その限定理由を以下に
述べる。
Ｃは直接焼入れによつて完全硬化組織を得るに
は、0.15wt％以上必要であり、また、直接焼入れ
によつて焼割れを防止するには0.35wt％以下であ
る必要があるためである。
Siは溶鋼の脱酸を完全にするためには、0.01wt
％以上必要であるが、0.5wt％以上の含有は鋼材
の延靭性を害するためである。
Mnは鋼材の焼入性確保の観点より0.4wt％以
上が必要であるが、2wt％以上の含有は鋼材の延
靭性および耐SSCC特性を損うため規定した。
SolAlは溶鋼の脱酸を完全にするためには
0.001wt％以上必要であるが、0.1wt％以上の含有
は鋼材の延靭性を損うためである。
Cu、Niはそれぞれ1wt％以下の添加により耐
SSCC特性を損わず焼入性を向上すると共に、固
溶強化により材料強度を高めることができるが、
限定値を越える添加は製造コストの観点から望し
くない。
Cr、Moも夫々2wt％以下の添加により耐SSCC
特性を損なわずに焼入性を向上すると共に、析出
強化により材料強度を高めることができるが、限
定値を越える添加は製造コストの観点から望まし
くない。
Ｖは0.2wt％以下の添加により、耐SSCC特性
を損なわずに焼入性を向上すると共に、析出強化
を通して材料強度を高めるが、0.2wt％以上の添
加は製造コストの観点から望ましくない。
Nb、Tiは既述のように旧オーステナイト粒の
展伸化を促進するのに有効な元素であるが、
0.1wt％を超える添加は効果が飽和となるため上
限を規定した。
REM、Caは0.1wt％以下の添加によりMnS介
在物の形態を球状化し、鋼材の延靭性を改善する
が、限定値以上の添加はかえつて延靭性を害し、
また、耐SSCC特性に対しては影響を与えないか
らである。
本発明は上記の限定された組成の鋼を直接焼入
れプロセスにより組織制御し、焼戻しマルテンサ
イト組織において、旧オーステナイト粒展伸度Ｒ
＝dL／dZ＞２とする。この理由は既述のとおりで
あるが、付言するならば、未再結晶領域の熱間加
工によつて得られる展伸した旧オーステナイト粒
は、直接焼入れ処理によつて始めて保存されるも
のであり、再加熱焼入れ処理によつては展伸した
旧オーステナイト粒は得られない。
（実施例）
次に本発明の具体的な実施例を比較例と共に示
す。
まず、本発明法の実施により得られた鋼（以下
本発明鋼という）と比較鋼の化学成分を第１表に
示す。
(Industrial Application Field) The present invention relates to a method for producing steel with excellent sulfide stress corrosion cracking resistance (hereinafter referred to as SSCC resistance) by direct quenching and tempering. (Conventional technology and its problems) In recent years, many gas fields and oil fields for sour gas and sour oil have been developed, and along with this, the
There is a need for steel materials for oil country tubular goods with excellent SSCC properties. As this type of steel material with yield strength of 50-80Kg/mm grade 2 ,
Conventionally, C-Si-Mn steel or C-Si-Mn-
Although manufactured by quenching and tempering Cr-Mo steel, these steel materials still have the following problems. C-Si-Mo steel has a yield strength of 60-80Kg/ mm2
Sufficient SSCC resistance properties have not been obtained in high-strength steels of this grade. C-Si-Mn-Cr-Mo steel has higher SSCC resistance than C-Si-Mn steel, but
Since the amounts of Cr and Mo are large, high manufacturing costs are unavoidable. Corrosive environmental conditions in sour gas and sour oil are becoming increasingly severe, and C-Si-
Mn-Cr-Mo steel is also required to have higher SSCC resistance, but this cannot be satisfactorily met. (Means for Solving the Problems) The present invention was devised through repeated research in view of the above-mentioned circumstances, and its purpose is to achieve microstructural control by a direct quenching process in the range of low-alloy steels. The objective is to utilize this technology to provide steel that maintains the same strength level as conventional steel but also has superior SSCC resistance properties. In order to achieve this object, the present invention focuses on and defines the prior austenite grain elongation of a tempered martensitic structure obtained by directly quenching and tempering steel of a predetermined composition after hot working, that is, C:
0.15~0.35wt%, Si: 0.01~0.50wt%, Mn: 0.4
A steel with a basic composition of ~2.0wt%, SolAl: 0.001~0.10wt%, and the balance consisting of Fe and unavoidable impurities is directly quenched after hot working above the Ac3 transformation point,
In the tempered martensitic structure obtained by subsequently tempering below the Ac 1 transformation point, R
It is characterized in that the prior austenite grain expansion elongation expressed by = (prior austenite grain size d L in the rolling direction)/(prior austenite grain size d Z in the wall thickness direction) is 2 or more. Regarding the composition of the steel in the above steel manufacturing method, in addition to the above basic composition, Cu of 1wt% or less, 1wt%
Contains one or two of the following Ni or 2wt%
Contains one or two of the following Cr, 2wt% or less Mo, 0.2wt% or less V, or contains 0.1wt% or less
Contains one or two of Nb, 0.1wt% or less of Ti, 0.1wt% or less of REM, 0.1wt% or less of Ti.
When one type or two types of Ca are contained, or when these are added in combination, products with more excellent various properties can be obtained. The present invention will be explained in detail below. First, the present inventors focused on the shape of crystal grains (prior austenite grains in the case of low alloy steel subjected to quenching and tempering) as one of the metallurgical factors that improve SSCC resistance. In order to examine the influence of the shape of prior austenite grains on SSCC resistance, we investigated the SSCC resistance of steel materials subjected to direct quenching and tempering treatment, in which the shape of prior austenite grains can be controlled by changing hot working conditions. . Figure 1 shows 0.21C-0.22Si-1.32Mn steel (YS=74~
76Kg/mm 2 ), it shows the rolling reduction ratio in the non-recrystallization temperature range that affects the SSCC resistance properties when directly quenched 15 seconds after finishing rolling. As is clear from Fig. 1, under direct quenching and tempering conditions, the reduction rate in the non-recrystallization temperature region is
When it is 30% or more, the elongation degree R of the prior austenite grain size (prior austenite grain size d L in the rolling direction / prior austenite grain size d Z in the wall thickness direction) becomes 2 or more, and in this region, the SSCC resistance property (this In this case, the critical cracking stress Sc value in a three-point bending test in a 0.5% acetic acid H 2 S saturated solution has been improved. On the other hand, if the reduction rate in the non-recrystallized area is less than 30%,
The degree of elongation of the prior austenite grain size is less than 2,
The improvement in Sc value is not very large. The present invention is based on this knowledge, and the reason why the SSCC resistance is improved by elongation of prior austenite grains is that the propagation of cracks that occur on the steel surface in the thickness direction causes prior austenite that is elongated in the rolling direction. This is due to the fact that it is easily deflected along grain boundaries, and if the prior austenite elongation R is less than 2, the
Not effective in improving SSCC characteristics. Therefore, the elongation of prior austenite grains, which is effective in improving SSCC resistance, is promoted by the addition of a small amount of Nb or Ti. Figure 2 is 0.2C−0.2Si−1.3Mn−
This shows the results of examining the effect of Nb addition on Nb steel (YS = 74 to 76 Kg/mm 2 ).Even under the same hot rolling-direct quenching and tempering conditions, the SSCC resistance was significantly improved by adding a small amount of Nb. has been improved. In other words, for Nb-free steel, rolling conditions (900
Only when the rolling reduction rate is 70% below ℃, and the finishing temperature of rolling is 870℃), the degree of elongation becomes R>2, and the rolling conditions (1000
When the rolling reduction is 70% and the finishing temperature is 920°C), R<2. On the other hand, in Nb-added steel,
It can be seen that R>2 under both rolling conditions, and the SSCC resistance properties are significantly improved under such conditions. The improvement effect of SSCC resistance due to elongation of prior austonite grains can be seen in C-Si-Mn-Cr-Mo steels (e.g.,
Of course, it can also be obtained with 0.3C-0.2Si-0.5Mn-1Cr-0.5Mo steel). In view of the above points, the present invention adopts the configuration described above, and the reasons for the limitations will be described below. This is because C needs to be at least 0.15 wt% to obtain a completely hardened structure by direct quenching, and 0.35 wt% or less to prevent quench cracking by direct quenching. Si must be 0.01wt to completely deoxidize molten steel.
% or more is necessary, but if the content is 0.5wt% or more, it will impair the ductility and toughness of the steel material. Mn is required to be at least 0.4 wt% from the perspective of ensuring the hardenability of the steel material, but it was specified because the content of 2 wt% or more would impair the ductility and SSCC resistance of the steel material. SolAl is required to completely deoxidize molten steel.
It is necessary to contain 0.001wt% or more, but this is because the content of 0.1wt% or more impairs the ductility and toughness of the steel material. Cu and Ni are resistant by adding less than 1wt% each.
Hardenability can be improved without impairing SSCC properties, and material strength can be increased through solid solution strengthening.
Addition exceeding the limited value is undesirable from the viewpoint of manufacturing costs. SSCC resistance is achieved by adding Cr and Mo at 2wt% or less each.
Although it is possible to improve hardenability without impairing properties and increase material strength through precipitation strengthening, addition in excess of a limited value is undesirable from the viewpoint of manufacturing costs. Addition of 0.2 wt% or less of V improves hardenability without impairing SSCC resistance, and increases material strength through precipitation strengthening, but addition of 0.2 wt% or more is undesirable from the viewpoint of manufacturing cost. As mentioned above, Nb and Ti are effective elements for promoting elongation of prior austenite grains, but
Addition of more than 0.1 wt% results in saturation of the effect, so an upper limit was defined. When REM and Ca are added in an amount of 0.1wt% or less, the morphology of MnS inclusions becomes spheroidized and the ductility of the steel material is improved. However, when added in an amount exceeding a limited value, the ductility and toughness are adversely affected.
Further, this is because it does not affect the SSCC resistance characteristics. The present invention controls the structure of steel with the above-mentioned limited composition through a direct quenching process, and in the tempered martensitic structure, the prior austenite grain expansion elongation R
=d L /d Z >2. The reason for this has already been mentioned, but it should be added that the expanded prior austenite grains obtained by hot working in the non-recrystallized region can only be preserved by direct quenching. , expanded prior austenite grains cannot be obtained by reheating and quenching. (Example) Next, specific examples of the present invention will be shown together with comparative examples. First, Table 1 shows the chemical components of the steel obtained by implementing the method of the present invention (hereinafter referred to as the steel of the present invention) and comparative steel.
【表】【table】
【表】
第２表は第１表に示す各鋼の熱間圧延、熱処理
条件と旧オーステナイト粒の展伸度、降伏強さ及
び耐SSCC特性の検討結果を示すものである。[Table] Table 2 shows the hot rolling and heat treatment conditions of each steel shown in Table 1, as well as the study results of the degree of elongation of prior austenite grains, yield strength, and SSCC resistance properties.
【表】
上記第１表及び第２表から、本発明鋼において
は、Nb添加の有無にかかわらず、旧オーステナ
イト粒展伸度が２以上となつているが、比較鋼は
いずれも旧オーステナイト粒展伸度が２未満とな
つている。そして、本発明鋼はいずれもそれぞれ
対応する比較鋼に比べ、略強度的に同等であつ
て、しかも優れた耐SSCC特性が得られている。
（発明の効果）
以上説明した本発明によるときには、必要な強
度水準を保ちつつ、しかも優れた耐SSCC特性を
備えた鋼を製造することができ、ことに低合金鋼
の範囲において優れた耐SSCC特性の鋼材とする
ことができるため、サワーガス、サワーオイルの
ガス田、油田等における油井管用鋼材として好適
なものを提供できるものである。[Table] From Tables 1 and 2 above, in the steel of the present invention, the prior austenite grain expansion elongation is 2 or more regardless of the presence or absence of Nb addition, but in all comparative steels, the prior austenite grain The degree of elongation is less than 2. All of the steels of the present invention have approximately the same strength as the corresponding comparative steels, and also have excellent SSCC resistance. (Effects of the Invention) According to the present invention as described above, it is possible to manufacture steel that has excellent SSCC resistance while maintaining the necessary strength level, and particularly has excellent SSCC resistance in the range of low alloy steel. Since it can be made into a steel material with special characteristics, it can be provided as a steel material suitable for oil country tubular goods in gas fields, oil fields, etc. for sour gas and sour oil.
第１図は耐SSCC特性に及ぼす未再結晶温度領
域の圧下率の影響を示すグラフ、第２図は耐
SSCC特性に及ぼすNb添加の影響を示すグラフ
である。
Figure 1 is a graph showing the influence of rolling reduction in the non-recrystallization temperature range on SSCC resistance characteristics, and Figure 2 is a graph showing the influence of rolling reduction in the non-recrystallization temperature range on SSCC resistance characteristics.
3 is a graph showing the influence of Nb addition on SSCC characteristics.
Claims (1)
Mn：0.4〜2.0wt％、SolAl：0.001〜0.10wt％の
基本組成を有し、残部Feおよび不可避的不純物
からなる鋼を、Ac3変態点以上で熱間加工後直接
焼入れし、その後Ac1変態点以下で焼戻しするこ
とによつて得られる焼戻しマルテンサイト組成に
おいて、Ｒ＝（圧延方向の旧オーステナイト粒径
dL）／（肉厚方向の旧オーステナイト粒径dZ）に
よつて示される旧オーステナイト粒展伸度を２以
上とすることを特徴とする直接焼入れ焼戻しによ
る耐SSCC特性の優れた鋼の製造方法。 ２ Ｃ：0.15〜0.35wt％、Si：0.01〜0.50wt％、
Mn：0.4〜2.0wt％、SolAl：0.001〜0.10wt％の
基本組成を有するとともに、1wt％以下のCu、
1wt％以下のNiのうち１種又は２種を添加し、残
部Feおよび不可避的不純物からなる鋼を、Ac3変
態点以上で熱間加工後直接焼入れし、その後Ac1
変態点以下で焼戻しすることによつて得られる焼
戻しマルテンサイト組成において、Ｒ＝（圧延方
向の旧オーステナイト粒径dL）／（肉厚方向の旧
オーステナイト粒径dZ）によつて示される旧オー
ステナイト粒展伸度を２以上とすることを特徴と
する直接焼入れ焼戻しによる耐SSCC特性の優れ
た鋼の製造方法。 ３ Ｃ：0.15〜0.35wt％、Si：0.01〜0.50wt％、
Mn：0.4〜2.0wt％、SolAl：0.001〜0.10wt％の
基本組成を有するとともに、2wt％以下のCr、
2wt％以下のMo、0.2wt％以下のＶのうち１種又
は２種以上を添加し、残部Feおよび不可避的不
純物からなる鋼を、Ac3変態点以上で熱間加工後
直接焼入れし、その後Ac1変態点以下で焼戻しす
ることによつて得られる焼戻しマルテンサイト組
成において、Ｒ＝（圧延方向の旧オーステナイト
粒径dL）／（肉厚方向の旧オーステナイト粒径
dZ）によつて示される旧オーステナイト粒展伸度
を２以上とすることを特徴とする直接焼入れ焼戻
しによる耐SSCC特性の優れた鋼の製造方法。 ４ Ｃ：0.15〜0.35wt％、Si：0.01〜0.50wt％、
Mn：0.4〜2.0wt％、SolAl：0.001〜0.10wt％の
基本組成を有するとともに、0.1wt％以下のNb、
0.1wt％以下のTiのうち１種又は２種を添加し、
残部Feおよび不可避的不純物からなる鋼を、Ac3
変態点以上で熱間加工後直接焼入れし、その後
Ac1変態点以下で焼戻しすることによつて得られ
る焼戻しマルテンサイト組成において、Ｒ＝（圧
延方向の旧オーステナイト粒径dL）／（肉厚方向
の旧オーステナイト粒径dZ）によつて示される旧
オーステナイト粒展伸度を２以上とすることを特
徴とする直接焼入れ焼戻しによる耐SSCC特性の
優れた鋼の製造方法。 ５ Ｃ：0.15〜0.35wt％、Si：0.01〜0.50wt％、
Mn：0.4〜2.0wt％、SolAl：0.001〜0.10wt％の
基本組成を有するとともに、0.1wt％以下の
REM、0.1wt％以下のCaのうち１種又は２種を
添加し、残部Feおよび不可避的不純物からなる
鋼を、Ac3変態点以上で熱間加工後直接焼入れ
し、その後Ac1変態点以下で焼戻しすることによ
つて得られる焼戻しマルテンサイト組成におい
て、Ｒ＝（圧延方向の旧オーステナイト粒径
dL）／（肉厚方向の旧オーステナイト粒径dZ）に
よつて示される旧オーステナイト粒展伸度を２以
上とすることを特徴とする直接焼入れ焼戻しによ
る耐SSCC特性の優れた鋼の製造方法。 ６ Ｃ：0.15〜0.35wt％、Si：0.01〜0.50wt％、
Mn：0.4〜2.0wt％、SolAl：0.001〜0.10wt％の
基本組成を有するとともに、2wt％以下のCr、
2wt％以下のMo、0.2wt％以下のＶのうち１種又
は２種以上、0.1wt％以下のNb、0.1wt％以下の
Tiのうち１種又は２種を添加し、残部Feおよび
不可避的不純物からなる鋼を、Ac3変態点以上で
熱間加工後直接焼入れし、その後Ac1変態点以下
で焼戻しすることによつて得られる焼戻しマルテ
ンサイト組成において、Ｒ＝（圧延方向の旧オー
ステナイト粒径dL）／（肉厚方向の旧オーステナ
イト粒径dZ）によつて示される旧オーステナイト
粒展伸度を２以上とすることを特徴とする直接焼
入れ焼戻しによる耐SSCC特性の優れた鋼の製造
方法。[Claims] 1 C: 0.15 to 0.35 wt%, Si: 0.01 to 0.50 wt%,
A steel having a basic composition of Mn: 0.4 to 2.0 wt%, SolAl: 0.001 to 0.10 wt%, and the balance consisting of Fe and unavoidable impurities is directly quenched after hot working above the Ac 3 transformation point, then Ac 1 In the tempered martensite composition obtained by tempering below the transformation point, R = (prior austenite grain size in the rolling direction)
Production of steel with excellent SSCC resistance by direct quenching and tempering, characterized by having a prior austenite grain expansion elongation expressed by d L )/(prior austenite grain size in the thickness direction d Z ) of 2 or more. Method. 2 C: 0.15-0.35wt%, Si: 0.01-0.50wt%,
It has a basic composition of Mn: 0.4 to 2.0 wt%, SolAl: 0.001 to 0.10 wt%, and Cu of 1 wt% or less,
A steel containing one or two types of Ni in an amount of 1 wt% or less and the balance consisting of Fe and unavoidable impurities is directly quenched after hot working above the Ac 3 transformation point, and then directly quenched to Ac 1.
In the tempered martensite composition obtained by tempering below the transformation point, the prior austenite grain size expressed by R = (prior austenite grain size in the rolling direction d L )/(prior austenite grain size in the wall thickness direction d Z ) A method for producing steel with excellent SSCC resistance by direct quenching and tempering, characterized in that the austenite grain elongation is 2 or more. 3 C: 0.15-0.35wt%, Si: 0.01-0.50wt%,
It has a basic composition of Mn: 0.4 to 2.0 wt%, SolAl: 0.001 to 0.10 wt%, and Cr of 2 wt% or less,
Steel containing one or more of 2wt% or less Mo and 0.2wt% or less V, with the remainder Fe and unavoidable impurities, is directly quenched after hot working at the Ac 3 transformation point or higher, and then In the tempered martensite composition obtained by tempering below the Ac 1 transformation point, R = (prior austenite grain size in the rolling direction d L )/(prior austenite grain size in the thickness direction)
A method for producing steel with excellent SSCC resistance by direct quenching and tempering, characterized in that the prior austenite grain elongation indicated by dZ ) is 2 or more. 4 C: 0.15-0.35wt%, Si: 0.01-0.50wt%,
It has a basic composition of Mn: 0.4 to 2.0 wt%, SolAl: 0.001 to 0.10 wt%, and Nb of 0.1 wt% or less,
Adding one or two types of Ti at 0.1wt% or less,
Steel consisting of balance Fe and unavoidable impurities is Ac 3
Directly quenched after hot working above the transformation point, then
In the tempered martensite composition obtained by tempering below the Ac 1 transformation point, R = (prior austenite grain size in the rolling direction d L )/(prior austenite grain size in the thickness direction d Z ). A method for producing steel with excellent SSCC resistance by direct quenching and tempering, characterized in that the prior austenite grain expansion elongation is 2 or more. 5 C: 0.15-0.35wt%, Si: 0.01-0.50wt%,
It has a basic composition of Mn: 0.4-2.0wt%, SolAl: 0.001-0.10wt%, and 0.1wt% or less
REM, steel containing one or two types of Ca added up to 0.1wt% and the balance Fe and unavoidable impurities is directly quenched after hot working at a temperature above the Ac 3 transformation point, and then directly quenched at a temperature below the Ac 1 transformation point. In the tempered martensite composition obtained by tempering at
Production of steel with excellent SSCC resistance by direct quenching and tempering, characterized by having a prior austenite grain expansion elongation expressed by d L )/(prior austenite grain size in the thickness direction d Z ) of 2 or more. Method. 6 C: 0.15-0.35wt%, Si: 0.01-0.50wt%,
It has a basic composition of Mn: 0.4 to 2.0 wt%, SolAl: 0.001 to 0.10 wt%, and Cr of 2 wt% or less,
2wt% or less Mo, 0.2wt% or less of V, one or more of them, 0.1wt% or less Nb, 0.1wt% or less
By adding one or two types of Ti, and directly quenching the steel consisting of Fe and unavoidable impurities above the Ac 3 transformation point after hot working, and then tempering it below the Ac 1 transformation point. In the tempered martensite composition obtained, the prior austenite grain expansion elongation represented by R = (prior austenite grain size d L in the rolling direction) / (prior austenite grain size d Z in the wall thickness direction) is set to 2 or more. A method for manufacturing steel with excellent SSCC resistance characteristics by direct quenching and tempering.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16861985A JPS6230849A (en) | 1985-08-01 | 1985-08-01 | Directly quenched and tempered steel having superior sscc resistance characteristic |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16861985A JPS6230849A (en) | 1985-08-01 | 1985-08-01 | Directly quenched and tempered steel having superior sscc resistance characteristic |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6230849A JPS6230849A (en) | 1987-02-09 |
| JPH049847B2 true JPH049847B2 (en) | 1992-02-21 |
Family
ID=15871416
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16861985A Granted JPS6230849A (en) | 1985-08-01 | 1985-08-01 | Directly quenched and tempered steel having superior sscc resistance characteristic |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6230849A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4765168A (en) * | 1987-07-27 | 1988-08-23 | Tools For Bending, Inc. | Method and apparatus for bending tubing |
| JP2733807B2 (en) * | 1991-06-07 | 1998-03-30 | 株式会社日本製鋼所 | Welded structural steel with excellent sulfide stress corrosion cracking resistance and low-temperature toughness |
| WO1996036742A1 (en) * | 1995-05-15 | 1996-11-21 | Sumitomo Metal Industries, Ltd. | Process for producing high-strength seamless steel pipe having excellent sulfide stress cracking resistance |
Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5471714A (en) * | 1977-11-21 | 1979-06-08 | Nippon Kokan Kk <Nkk> | Manufacture of control-rolled high tensile steel with no separation |
| JPS54119324A (en) * | 1978-03-08 | 1979-09-17 | Kawasaki Steel Co | Production of steel pipe for oil well |
| JPS54124817A (en) * | 1978-03-23 | 1979-09-28 | Nippon Kokan Kk <Nkk> | Steel of excellent sulfide resistance and excellent corrosion crack resistance |
| JPS5613463A (en) * | 1979-07-10 | 1981-02-09 | Sumitomo Metal Ind Ltd | Line pipe steel with superior hydrogen sulfide crack resistance |
| JPS5613462A (en) * | 1979-07-10 | 1981-02-09 | Sumitomo Metal Ind Ltd | Line pipe steel with superior hydrogen sulfide crack resistance |
| JPS56119759A (en) * | 1980-02-28 | 1981-09-19 | Nippon Kokan Kk <Nkk> | High tensile steel with superior sulfide corrosion crack resistance |
| JPS589919A (en) * | 1981-07-09 | 1983-01-20 | Kawasaki Steel Corp | Production of high tensile hot rolled steel strip of superior low temperature toughness |
| JPS5858252A (en) * | 1981-10-02 | 1983-04-06 | Kawasaki Steel Corp | Steel for steel pipe for oil well |
| JPS58107476A (en) * | 1981-12-19 | 1983-06-27 | Kawasaki Steel Corp | High tensile steel excellent sulfide stress corrosion cracking resistance |
| JPS58199818A (en) * | 1982-05-17 | 1983-11-21 | Nippon Steel Corp | Manufacture of high strength steel pipe for oil well |
| JPS58204159A (en) * | 1982-05-24 | 1983-11-28 | Japan Steel Works Ltd:The | Sulfide crack resistant thick steel with superior weldability |
| JPS5913052A (en) * | 1982-02-19 | 1984-01-23 | Kawasaki Steel Corp | Stainless steel material with high strength and superior resistance to corrosion, stress corrosion cracking and cracking due to sulfide and its manufacture |
| JPS6067620A (en) * | 1983-09-21 | 1985-04-18 | Kobe Steel Ltd | Preparation of steel plate |
| JPS6096718A (en) * | 1983-10-31 | 1985-05-30 | Kobe Steel Ltd | Manufacture of steel sheet excellent in resistances to hydrogen inducing cracking and stress corrosion crcking |
-
1985
- 1985-08-01 JP JP16861985A patent/JPS6230849A/en active Granted
Patent Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5471714A (en) * | 1977-11-21 | 1979-06-08 | Nippon Kokan Kk <Nkk> | Manufacture of control-rolled high tensile steel with no separation |
| JPS54119324A (en) * | 1978-03-08 | 1979-09-17 | Kawasaki Steel Co | Production of steel pipe for oil well |
| JPS54124817A (en) * | 1978-03-23 | 1979-09-28 | Nippon Kokan Kk <Nkk> | Steel of excellent sulfide resistance and excellent corrosion crack resistance |
| JPS5613463A (en) * | 1979-07-10 | 1981-02-09 | Sumitomo Metal Ind Ltd | Line pipe steel with superior hydrogen sulfide crack resistance |
| JPS5613462A (en) * | 1979-07-10 | 1981-02-09 | Sumitomo Metal Ind Ltd | Line pipe steel with superior hydrogen sulfide crack resistance |
| JPS56119759A (en) * | 1980-02-28 | 1981-09-19 | Nippon Kokan Kk <Nkk> | High tensile steel with superior sulfide corrosion crack resistance |
| JPS589919A (en) * | 1981-07-09 | 1983-01-20 | Kawasaki Steel Corp | Production of high tensile hot rolled steel strip of superior low temperature toughness |
| JPS5858252A (en) * | 1981-10-02 | 1983-04-06 | Kawasaki Steel Corp | Steel for steel pipe for oil well |
| JPS58107476A (en) * | 1981-12-19 | 1983-06-27 | Kawasaki Steel Corp | High tensile steel excellent sulfide stress corrosion cracking resistance |
| JPS5913052A (en) * | 1982-02-19 | 1984-01-23 | Kawasaki Steel Corp | Stainless steel material with high strength and superior resistance to corrosion, stress corrosion cracking and cracking due to sulfide and its manufacture |
| JPS58199818A (en) * | 1982-05-17 | 1983-11-21 | Nippon Steel Corp | Manufacture of high strength steel pipe for oil well |
| JPS58204159A (en) * | 1982-05-24 | 1983-11-28 | Japan Steel Works Ltd:The | Sulfide crack resistant thick steel with superior weldability |
| JPS6067620A (en) * | 1983-09-21 | 1985-04-18 | Kobe Steel Ltd | Preparation of steel plate |
| JPS6096718A (en) * | 1983-10-31 | 1985-05-30 | Kobe Steel Ltd | Manufacture of steel sheet excellent in resistances to hydrogen inducing cracking and stress corrosion crcking |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6230849A (en) | 1987-02-09 |
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