JPH0480967B2 - - Google Patents
Info
- Publication number
- JPH0480967B2 JPH0480967B2 JP60195345A JP19534585A JPH0480967B2 JP H0480967 B2 JPH0480967 B2 JP H0480967B2 JP 60195345 A JP60195345 A JP 60195345A JP 19534585 A JP19534585 A JP 19534585A JP H0480967 B2 JPH0480967 B2 JP H0480967B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- steel plate
- steel
- strength
- diameter welded
- 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 41
- 239000010959 steel Substances 0.000 claims description 41
- 238000000034 method Methods 0.000 claims description 15
- 238000001816 cooling Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 238000005098 hot rolling Methods 0.000 claims description 3
- 238000005260 corrosion Methods 0.000 claims description 2
- 230000007797 corrosion Effects 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 230000000694 effects Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000005496 tempering Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
Landscapes
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Description
産業上の利用分野
本発明は、大径溶接鋼管用鋼板の製造方法に関
するものである。
従来の技術
大径溶接鋼管用鋼板ASTM規格A387Gr9（以下
9Cr−1Mo鋼という）は圧延後Ac3点以上に加熱
してから空冷の焼ならし処理を行なつた後焼戻し
処理を施し、該鋼板を例えばUOE方式（Ｕ型、
Ｏ型、継目をサブマージアーク溶接Ｅ）、UO方
式、プレスベント方式等により大径溶接鋼管を製
造するのが一般的である。先行技術としては例え
ば、特開昭56−35722号公報に開示されている如
くＢ添加により焼入れ性を向上させた鋼板を用い
て厚肉高張力大径鋼管を製造する方法もあるが、
本発明とは鋼種も技術思想も全く異にするもので
ある。
発明が解決しようとする問題点
9Cr−1Mo鋼からなる大径溶接鋼管用鋼板は圧
延後、焼純＋焼戻し、焼ならし＋焼戻し、の
２方法で熱処理されるが、の方法では、プレー
ト強度については問題がないが、焼純処理の際、
Ac3点上から常温まで炉冷せねばならず、長時間
かかり非能率的である。
の方法においても、焼ならし処理の際、Ac3
点以上に加熱してから空冷するのが常であり、板
厚50tでも600℃／Hr以上の冷却速度となる。該
冷却速度では大半がマルテンサイトと若干のベー
ナイトから成る非常に硬化した鋼板組織である。
該組織を靱性回復および強度低下の目的で焼戻
し、処理しても充分な値が得られないため必然的
に後工程の鋼管の製造可能範囲は薄肉大径溶接鋼
管に限定される。
このような薄肉大径溶接鋼管においてすら形状
が悪く、プレス後の残留応力も多大なため溶接時
の熱間ワレを助長することがある。ましてや厚肉
大径溶接鋼管の製造は困難であつた。そのため、
このような用途の鋼板には加工性、特に低降伏比
が要求される。つまり適当な引張強さと降伏強さ
が要求される他に、両者の適当なバランスが同時
に要求されるのである。これらの問題を解決する
ために従来は鋼板の焼戻しに多大な時間を要して
いた。
問題点を解決するための手段
本発明者等は、上記問題点を解決するために長
年にわたり試験を重ねた結果、Ｃ：0.15％以下、
Si：1.00％以下、Mn：0.30〜0.60％、Ｐ：0.030
％以下、Ｓ：0.030％以下、Cr：8.00〜10.00％、
Mo：0.90〜1.10％、残部：Feおよび不可避的不
純物よりなる9Cr−1Mo鋼板を熱間圧延後Ac3点
以上に加熱し、引き続きAc3〜Ac1の間を70℃／
Hr〜300℃／Hrの冷却速度で冷却することによ
つて鋼板の焼戻しに多大な時間を要することなく
加工しやすい高強度耐熱耐食性の優れた大径溶接
鋼管用鋼板の製造方法を提供するものである。
次に本発明の限定理由を説明する。
Ｃ：0.15％以上では 溶接性が悪化する。
Si：1.00％以上では 〃
Mn：0.30％未満では 強度および靱性値が
確保できない。
0.60％以上では 溶接性が劣化し材質
の異方性が増加し、パイプ母材板厚方向延性の低
下となる。
P.S：0.030％以上では 靱性が悪くなる。
Cr：8.00％未満では 強度が規格を満足しな
い。
10.00％以上では 強度が高くなりすぎ
経済的でない。
Mo：0.90％未満では 強度が規格を満足し
ない。
1.10％以上では 強度が高くなりすぎ
経済的でない。
又、Ac3〜Ac1の間の冷却速度が70℃／Hr未満
では鋼板のYS値（降伏強さ）が規格値206N／mm2
（30Ksi）を満足しない。
301℃／Hr以上となると鋼板のTS値（引張強
さ）が586N／mm2（85Ksi）以上となり、後工程の
製管時の加工性が悪化し、プレス加工後の残留応
力が大となり溶接時の熱間ワレを助長するので
300℃／Hr以下とした。これらの結果を表示した
のが第１図である。従つて冷却時間やエネルギー
消費量および鋼板の強度バランス等を考慮すれば
本発明においては、100℃／Hr〜200℃／Hrの冷
却速度が最も好ましい範囲といえる。本発明の鋼
板の厚さは一般に５mm〜50.8mm程度が多用され
る。該鋼板を用いて製造される製管の外径につい
ては、16inch〜42inch程度が多い。
又、本発明でいう9Cr−1Mo鋼板を用いる製管
方法にはUOE方式の他にUO方式、プレスベント
方式等がある。更に本発明でいうAc3とは約870
℃、Ac1とは約820℃のことをいい、冷却後必要
に応じて焼戻しすることもある。
作 用
9Cr−1Mo鋼を熱間圧延して鋼板とした後、
Ac3点以上に加熱し Ac1点までの温度範囲を70
℃／Hr〜300℃／Hrの冷却速度で冷却するので、
該鋼板の強度は低下し、かつプレス後の残留応力
も低くなり大径溶接鋼管の加工がしやすくなつ
た。
発明の効果
以上の作用に基づく本発明の効果としては、第
２図に示す如く、該処理を施した鋼板は加工がし
やすくなつたために鋼管外径16inch以上における
鋼管肉厚は最高1inchまでしか製管出来なかつた
が、該範囲に加えて鋼管肉厚が最高2inchまで
（第２図斜線部分）に製管範囲が拡大され大径溶
接鋼管の適用範囲は従来にも増して輸送配管分野
にまで拡がり製造原価の低減という大きなメリツ
トを生んだ。
実施例
以下に本発明の実施例を示す。
表−１の組成を有する9Cr−1Mo鋼の鋼板（厚
さ2inch）を用いてAc3点以上に加熱した後、Ac3
〜Ac1間を表−２の条件で熱処理を施した後、
UOE方式で外径40inchの管を製造し、その機械
的性質も併せて表示した。
INDUSTRIAL APPLICATION FIELD The present invention relates to a method of manufacturing a steel plate for large diameter welded steel pipes. Conventional technology Steel plate for large diameter welded steel pipes ASTM standard A387Gr9 (hereinafter
9Cr-1Mo steel) is heated to Ac 3 or above after rolling, air-cooled, normalized, and then tempered.
It is common to manufacture large diameter welded steel pipes using O type, submerged arc welding (E), UO method, press bent method, etc. As a prior art, for example, there is a method of manufacturing a thick-walled, high-tensile, large-diameter steel pipe using a steel plate whose hardenability has been improved by adding B, as disclosed in JP-A No. 56-35722.
The steel type and technical idea are completely different from the present invention. Problems to be Solved by the Invention After rolling, steel plates for large-diameter welded steel pipes made of 9Cr-1Mo steel are heat-treated by two methods: quenching + tempering and normalizing + tempering. There is no problem with this, but during the sintering process,
The furnace must be cooled from above the Ac 3 point to room temperature, which takes a long time and is inefficient. In this method, Ac 3
It is customary to heat the material above a point and then air cool it, and even with a thickness of 50 tons, the cooling rate is over 600°C/Hr. At this cooling rate, the steel sheet has a very hardened structure consisting mostly of martensite and some bainite.
Even if the structure is tempered and treated for the purpose of recovering toughness and reducing strength, sufficient values cannot be obtained, so the range of steel pipes that can be manufactured in the subsequent process is inevitably limited to thin-walled, large-diameter welded steel pipes. Even such thin-walled, large-diameter welded steel pipes have poor shapes and have a large amount of residual stress after pressing, which may promote hot cracking during welding. Furthermore, it was difficult to manufacture thick-walled, large-diameter welded steel pipes. Therefore,
Steel sheets for such uses are required to have workability, especially a low yield ratio. In other words, in addition to requiring appropriate tensile strength and yield strength, an appropriate balance between the two is also required. Conventionally, in order to solve these problems, it took a long time to temper the steel plate. Means for Solving the Problems As a result of many years of repeated tests to solve the above problems, the inventors have found that C: 0.15% or less;
Si: 1.00% or less, Mn: 0.30-0.60%, P: 0.030
% or less, S: 0.030% or less, Cr: 8.00-10.00%,
A 9Cr-1Mo steel sheet consisting of Mo: 0.90~1.10%, balance: Fe and unavoidable impurities is heated to Ac 3 or higher after hot rolling, and then heated at 70℃/ac between Ac 3 and Ac 1 .
To provide a method for producing a steel plate for large-diameter welded steel pipes, which is easy to process and has high strength, excellent heat resistance, and corrosion resistance, by cooling at a cooling rate of Hr to 300°C/Hr without requiring a large amount of time for tempering the steel plate. It is. Next, the reasons for the limitations of the present invention will be explained. C: At 0.15% or more, weldability deteriorates. Si: 1.00% or more, Mn: less than 0.30%, strength and toughness values cannot be secured. If it exceeds 0.60%, weldability deteriorates, the anisotropy of the material increases, and the ductility of the pipe base material in the thickness direction decreases. PS: Toughness deteriorates at 0.030% or more. If Cr: is less than 8.00%, the strength will not meet the standard. If it exceeds 10.00%, the strength becomes too high and it is not economical. If Mo: less than 0.90%, the strength will not meet the standard. If it exceeds 1.10%, the strength becomes too high and it is not economical. Also, if the cooling rate between Ac 3 and Ac 1 is less than 70℃/Hr, the YS value (yield strength) of the steel plate will be the standard value of 206N/mm 2
(30Ksi) is not satisfied. If the temperature exceeds 301℃/Hr, the TS value (tensile strength) of the steel plate will exceed 586N/mm 2 (85Ksi), which will deteriorate workability during pipe manufacturing in the subsequent process, and increase residual stress after press forming, making it difficult to weld. Because it promotes hot cracking during
The temperature was set to 300℃/Hr or less. FIG. 1 shows these results. Therefore, in consideration of the cooling time, energy consumption, strength balance of the steel plate, etc., in the present invention, a cooling rate of 100° C./Hr to 200° C./Hr is the most preferable range. The thickness of the steel plate of the present invention is generally about 5 mm to 50.8 mm. The outer diameter of pipes manufactured using the steel plate is often about 16 inches to 42 inches. In addition, the pipe manufacturing method using the 9Cr-1Mo steel plate referred to in the present invention includes the UO method, the press bend method, etc. in addition to the UOE method. Furthermore, Ac 3 in the present invention is approximately 870
℃, Ac 1 refers to approximately 820℃, and may be tempered if necessary after cooling. Action After hot rolling 9Cr-1Mo steel into a steel plate,
Heating to AC 3 points or more and temperature range up to AC 1 point 70
Since it cools at a cooling rate of ℃/Hr to 300℃/Hr,
The strength of the steel plate was lowered, and the residual stress after pressing was also lower, making it easier to process large-diameter welded steel pipes. Effects of the Invention As shown in Figure 2, the effect of the present invention based on the above-mentioned effects is that the treated steel plate is easier to work with, so that the wall thickness of steel pipes with an outer diameter of 16 inches or more can only reach a maximum of 1 inch. However, in addition to this range, the pipe manufacturing range has been expanded to a maximum wall thickness of 2 inches (shaded area in Figure 2), and the scope of application of large-diameter welded steel pipes has expanded to the field of transportation piping. This has led to the great benefit of reducing manufacturing costs. Examples Examples of the present invention are shown below. After heating a 9Cr-1Mo steel plate (2 inch thick) having the composition shown in Table 1 to Ac 3 points or more, Ac 3
After heat treatment between ~ Ac 1 under the conditions shown in Table 2,
A tube with an outer diameter of 40 inches was manufactured using the UOE method, and its mechanical properties were also displayed.
【表】【table】
第１図は鋼板強度とAc3〜Ac1の冷却速度の関
係を示す図、第２図は鋼管肉厚と鋼管外径の関係
を示す図である。
FIG. 1 is a diagram showing the relationship between the steel plate strength and the cooling rate of Ac 3 to Ac 1 , and FIG. 2 is a diagram showing the relationship between the steel pipe wall thickness and the steel pipe outer diameter.
Claims (1)
〜0.60％、Ｐ：0.030％以下、Ｓ：0.030％以下、
Cr：8.00〜10.00％、Mo：0.90〜1.10％、残部：
Feおよび不可避的不純物よりなる鋼板を熱間圧
延後Ac3点以上に加熱し、引き続きAc3〜Ac1の
間を70℃／Hr〜300℃／Hrの冷却速度で冷却す
ることを特徴とする加工しやすい高強度耐熱耐食
性の優れた大径溶接鋼管用鋼板の製造方法。1 C: 0.15% or less, Si: 1.00% or less, Mn: 0.30
~0.60%, P: 0.030% or less, S: 0.030% or less,
Cr: 8.00~10.00%, Mo: 0.90~1.10%, balance:
A steel plate consisting of Fe and inevitable impurities is heated to Ac 3 or more after hot rolling, and then cooled between Ac 3 and Ac 1 at a cooling rate of 70°C/Hr to 300°C/Hr. A method for manufacturing large-diameter welded steel plates for large-diameter welded pipes that are easy to process, have high strength, and have excellent heat and corrosion resistance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19534585A JPS6256530A (en) | 1985-09-04 | 1985-09-04 | Manufacture of steel sheet for welded steel pipe of large diameter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19534585A JPS6256530A (en) | 1985-09-04 | 1985-09-04 | Manufacture of steel sheet for welded steel pipe of large diameter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6256530A JPS6256530A (en) | 1987-03-12 |
| JPH0480967B2 true JPH0480967B2 (en) | 1992-12-21 |
Family
ID=16339623
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19534585A Granted JPS6256530A (en) | 1985-09-04 | 1985-09-04 | Manufacture of steel sheet for welded steel pipe of large diameter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6256530A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3825634C2 (en) * | 1988-07-28 | 1994-06-30 | Thyssen Stahl Ag | Process for the production of hot baths or heavy plates |
| WO1996002678A1 (en) * | 1994-07-18 | 1996-02-01 | Nippon Steel Corporation | Process for producing steel material and steel pipe excellent in corrosion resistance and weldability |
| KR100516515B1 (en) * | 2001-12-22 | 2005-09-26 | 주식회사 포스코 | A method for heat treating the laying head pipe having superior wear resistance |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5839891A (en) * | 1981-09-04 | 1983-03-08 | シヨ−ボンド建設株式会社 | Pipe joint |
-
1985
- 1985-09-04 JP JP19534585A patent/JPS6256530A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6256530A (en) | 1987-03-12 |
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