JPS6353246B2 - - Google Patents
Info
- Publication number
- JPS6353246B2 JPS6353246B2 JP55166611A JP16661180A JPS6353246B2 JP S6353246 B2 JPS6353246 B2 JP S6353246B2 JP 55166611 A JP55166611 A JP 55166611A JP 16661180 A JP16661180 A JP 16661180A JP S6353246 B2 JPS6353246 B2 JP S6353246B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- free
- stress relief
- cracking
- relief annealing
- 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
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 20
- 239000010959 steel Substances 0.000 claims description 20
- 238000005336 cracking Methods 0.000 claims description 13
- 238000000137 annealing Methods 0.000 claims description 10
- 229910052684 Cerium Inorganic materials 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 description 7
- 238000003466 welding Methods 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
Description
本発明は溶接継手部が応力除去焼なまし割れ感
受性の低いＢ―Ｖ含有鋼の製造法に関するもので
ある。
溶接継手部には、溶接時の温度により応力が発
生し、冷却後に大きな応力を残留する。残留応力
は、継手形状，溶接入熱，母材の大きさなど多く
の因子に影響され、溶接部に割れを誘発する。特
にＢで焼入強化をはかりＶで焼戻強化をはかつた
80キロ級高張力鋼のＢ―Ｖ含有鋼は、溶接部の残
留応力を緩和するため、溶接後応力除去焼なまし
が行なわれている。しかしながらＢ―Ｖ含有鋼に
おいて応力除去焼なましは、残留応力を緩和させ
る良い方法ではあるが、溶接時高温度で溶解した
ＢおよびＶの析出物が粒界に析出して割れ起点を
形成し、割れ感受性を著しく低下せしめる方法で
はなかつた。また継手溶接した後溶接止端部を溶
接や機械加工によつて滑らかにして応力の集中を
防止する仕上方法が採用されているが、この方法
も充分な対策ではなく、しばしば問題を発生して
いた。
本発明者らはこのような問題に鑑み種々検討し
た結果、CaおよびCeの硫化物形成元素を添加す
ることが、Ｂ―Ｖ含有鋼の応力除去焼なまし感受
性を著しく低めることを知見した。本発明はこの
知見に基いて構成したもので、その要旨はＢ―Ｖ
含有鋼にCaまたはCeあるいはその両方を添加し
てＳ量（Sfree）を〔Ｓ−（Ca（％）／1.25＋Ce（％）
／4.38）〕
なる式で20ppm以下にすることにある。
以下、本発明について詳明に説明する。
転炉，電気炉等の溶解炉で溶製されたＢ：
0.0005〜0.0050％，Ｖ：0.01〜0.10％を含有した
80キロ級高張力鋼、さらにNb，Mo，Cr，Niな
どの強靫化成分を選択して添加した高張力高靫性
Ｂ―Ｖ含有鋼の如きＢ―Ｖ含有鋼に、硫化物形成
元素のCaまたはCeあるいはその両者を添加して
Sfree量を、Sfree＝〔Ｓ−（Ca（％）／1.25＋Ce（％）
／4.38）〕な
る式で20ppm以下にする。20ppm以下のSfreeは、
Ｓ成分の周りに析出して粒界割れの起点となるＢ
およびＶ析出物を減少せしめると同時に、粒界割
れを伝播し助長するSfreeを減少せしめて応力除去
焼なまし割れ性を低める効果がある。図は鋼ベー
ス成分（Ｃ：0.10％，Si：0.25％，Mn：1.0％，
Cu：0.21％，Cr：0.70％，Mo：0.41％）のＢ
（0.0010％）添加鋼，Ｖ（0.04％）添加鋼およびＢ
―Ｖ添加鋼の応力除去焼なまし割れにSfreeが及ぼ
す影響を示したものである。すなわちSfreeの低減
化による割れ率の減少はＢ―Ｖ含有鋼において有
効であり、その量は特に20ppm以下で応力除去焼
なまし割れ感受性を低減する。
このような成分組成に調整された溶鋼は、造塊
分塊法あるいは連続鋳造法を経て鋼片となし、続
いて熱間圧延あるいは必要によつては熱処理工程
を行う通常の鋼板製造工程と製造条件で、鋼板製
品が製造される。
次に本発明の実施例について説明する。
転炉で溶製した溶鋼を連続鋳造，熱間圧延さら
に調質処理を施して製造した鋼を継手溶接し、次
いで応力除去焼鈍（温度575℃で１時間加熱）し
た。その時の供試鋼の成分および応力除去割れ性
を第１表に示した。
上記の結果から明らかなように本発明は比較鋼
に較べ割れ率が著しく小さく、応力除去焼なまし
割れ感受性が極めて低い。
The present invention relates to a method for producing BV-containing steel in which welded joints have low stress relief annealing cracking susceptibility. Stress is generated in the welded joint due to the temperature during welding, and large stress remains after cooling. Residual stress is influenced by many factors such as joint shape, welding heat input, and base metal size, and can induce cracks in the weld. In particular, B strengthened by quenching, and V strengthened by tempering.
80 kg class high tensile strength steel containing BV is subjected to stress relief annealing after welding to relieve residual stress in the welded area. However, although stress relief annealing is a good method for relieving residual stress in B-V containing steels, precipitates of B and V melted at high temperatures during welding precipitate at grain boundaries and form crack initiation points. However, this method did not significantly reduce cracking susceptibility. Furthermore, finishing methods have been adopted in which the weld toe is smoothed by welding or machining after the joint is welded to prevent stress concentration, but this method is not a sufficient countermeasure and often causes problems. Ta. The present inventors conducted various studies in view of these problems and found that addition of sulfide-forming elements such as Ca and Ce significantly lowers the stress relief annealing sensitivity of BV-containing steel. The present invention was constructed based on this knowledge, and its gist is B-V
By adding Ca or Ce or both to the containing steel, the amount of S (S free ) is increased [S-(Ca(%)/1.25+Ce(%))
/4.38)] The aim is to reduce the amount to 20ppm or less using the following formula. The present invention will be explained in detail below. B melted in a melting furnace such as a converter or electric furnace:
Contained 0.0005-0.0050%, V: 0.01-0.10%
Sulfide forming element by adding Ca or Ce or both
The amount of S free is calculated as follows: S free = [S - (Ca (%) / 1.25 + Ce (%))
/4.38)] below 20ppm. S free below 20ppm is
B precipitates around the S component and becomes the starting point of intergranular cracking.
This has the effect of reducing stress relief annealing cracking by reducing S free , which propagates and promotes intergranular cracking, as well as reducing V precipitates. The figure shows the steel base components (C: 0.10%, Si: 0.25%, Mn: 1.0%,
Cu: 0.21%, Cr: 0.70%, Mo: 0.41%) B
(0.0010%) additive steel, V (0.04%) additive steel and B
- This shows the influence of S free on stress relief annealing cracking of V-added steel. In other words, reducing the cracking rate by reducing S free is effective in steels containing BV, and the stress relief annealing cracking susceptibility is reduced especially when the amount is 20 ppm or less. Molten steel adjusted to such a chemical composition is made into steel billets through an ingot blooming method or continuous casting method, followed by hot rolling or, if necessary, a heat treatment process, which is the normal steel plate manufacturing process. Steel plate products are manufactured under these conditions. Next, examples of the present invention will be described. The molten steel produced in a converter was continuously cast, hot-rolled, and tempered. The steel was joint-welded and then stress-relieving annealed (heated at 575°C for 1 hour). Table 1 shows the composition and stress relief cracking properties of the test steel. As is clear from the above results, the cracking rate of the present invention is significantly lower than that of the comparative steel, and the stress relief annealing cracking susceptibility is extremely low.
【表】【table】
図面は応力除去焼なまし割れにSfreeが及ぼす影
響を示すグラフである。
The figure is a graph showing the influence of S free on stress relief annealing cracking.
Claims (1)
方を添加しかつSfree量を下記の式で20ppm以下に
することを特徴とする応力除去焼なまし割れ感受
性の低いＢ―Ｖ含有鋼の製造法。 Sfree＝〔Ｓ−（Ca（％）／1.25＋Ce（％）／4.38）〕[Claims] 1. A B with low stress relief annealing cracking susceptibility, characterized by adding Ca or Ce or both to B-V containing steel and setting the S free amount to 20 ppm or less according to the following formula. -Production method of V-containing steel. S free = [S-(Ca(%)/1.25+Ce(%)/4.38)]
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16661180A JPS5792125A (en) | 1980-11-28 | 1980-11-28 | Production of b-v-containing steel of low stress relief annealing crack sensitivity |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16661180A JPS5792125A (en) | 1980-11-28 | 1980-11-28 | Production of b-v-containing steel of low stress relief annealing crack sensitivity |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5792125A JPS5792125A (en) | 1982-06-08 |
| JPS6353246B2 true JPS6353246B2 (en) | 1988-10-21 |
Family
ID=15834510
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16661180A Granted JPS5792125A (en) | 1980-11-28 | 1980-11-28 | Production of b-v-containing steel of low stress relief annealing crack sensitivity |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5792125A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH067772B2 (en) * | 1989-04-26 | 1994-02-02 | 日東電工株式会社 | Microporous film for agricultural product cultivation and agricultural product cultivation method using the same |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59110765A (en) * | 1982-12-16 | 1984-06-26 | Kawasaki Steel Corp | Cr-mo steel for pressure container excellent in hydrogen corrosion resistant characteristics and sr crack-resistant |
| JPS60238451A (en) * | 1984-05-14 | 1985-11-27 | Kawasaki Steel Corp | High strength cr-mo steel for pressure vessel |
| JPS6156268A (en) * | 1984-08-24 | 1986-03-20 | Nippon Steel Corp | High toughness and high tensile steel and its manufacture |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52144318A (en) * | 1976-05-28 | 1977-12-01 | Nippon Steel Corp | Production of high tensile strength steel excllent in weldability and sr brittleness resistance |
-
1980
- 1980-11-28 JP JP16661180A patent/JPS5792125A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52144318A (en) * | 1976-05-28 | 1977-12-01 | Nippon Steel Corp | Production of high tensile strength steel excllent in weldability and sr brittleness resistance |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH067772B2 (en) * | 1989-04-26 | 1994-02-02 | 日東電工株式会社 | Microporous film for agricultural product cultivation and agricultural product cultivation method using the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5792125A (en) | 1982-06-08 |
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