WO2008075443A1 - 溶接熱影響部の靭性に優れた鋼 - Google Patents
溶接熱影響部の靭性に優れた鋼 Download PDFInfo
- Publication number
- WO2008075443A1 WO2008075443A1 PCT/JP2006/325984 JP2006325984W WO2008075443A1 WO 2008075443 A1 WO2008075443 A1 WO 2008075443A1 JP 2006325984 W JP2006325984 W JP 2006325984W WO 2008075443 A1 WO2008075443 A1 WO 2008075443A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- steel
- toughness
- less
- welding
- affected zone
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/50—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for welded joints
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
Definitions
- the present invention relates to a steel excellent in toughness of a weld heat affected zone (HAZ) in small heat input welding to medium heat input welding and a method for producing the same.
- HAZ weld heat affected zone
- the HA Z toughness of low alloy steels is: (1) grain size, (2) high carbon martensite (M *), upper vanite (Bu) and disperse of hardened phases such as ferrite side braid (FSP) State, (3) Precipitation Hardening state, (4) Presence / absence of grain boundary embrittlement, and (5) Elemental microsegregation.
- the microstructure of T i, ⁇ , N is optimized by refinement of the microstructure using Ti oxide in steel that does not substantially contain A 1, and in addition to that of Ti C It is known to suppress precipitation, reduce precipitation hardening, and improve toughness (Japanese Laid-Open Patent Publication No. 5-244753).
- the toughness of the heat affected zone is determined by This is determined by the balance of the effects of the hardened layer, and the conventional technology has been able to solve the problem by improving the toughness of the base material matrix using Ni.
- the addition of a large amount of expensive alloy elements such as Cu and Ni which are indispensable for the realization of this technology, leads to an increase in manufacturing cost and becomes an obstacle to manufacturing high-strength steel with excellent CTOD characteristics. It was.
- the steel according to the present invention does not substantially contain Al or Nb is also utilized in the present invention.
- the C content is high, the problem of reduced toughness when the Mn content is increased has not been solved.
- Nb and V as impurities would adversely affect toughness.
- Japanese Patent Laid-Open No. 2 0 3 -1 4 7 4 8 4 the idea of Japanese Patent Laid-Open No. 5-2 4 7 5 3 1 is followed, while using Ti oxide, Nb is added and Increase Mn content. As a result, the austenite-ferrite transformation start temperature is lowered to suppress the formation of the hardening phase, and at the same time, an appropriate microstructure is obtained, and the ⁇ 10 ° C C TO D characteristic is satisfied.
- the required C TO D characteristics of welded joints are not sufficiently satisfied at a stricter level of ⁇ 40 ° C. or lower. Disclosure of the invention
- the present invention provides a technique for inexpensively producing high-strength steel having excellent toughness in multilayer welding with small to medium heat input.
- the steel produced according to the present invention has extremely good CT0D characteristics of multi-layer welds with small to medium heat input, among the toughness of the heat affected zone.
- the gist of the present invention is as follows.
- a steel excellent in the toughness of the heat affected zone of welding characterized in that CeH represented by the formula (A) is in the range of 0.04 or less.
- C, S i, M n, C u, N i, N b, and V represent steel components (mass%), respectively.
- the toughness of the heat affected zone which is characterized by heat-treating a steel slab satisfying the steel composition described in (1) and C e H to a temperature of 110 ° C or lower and then heat treating it. Excellent steel manufacturing method.
- Fig. 1 shows the relationship between the cooling time from 800 to 500 ° C and the M * fraction.
- Figure 2 shows the relationship between C e H and CT OD characteristics.
- the local regions that have the greatest effect on C TOD characteristics are the hardened phases such as M * and ferrite side plates (FSP).
- M * and FSP ferrite side plates
- the feature of the present invention is that the following has been found, and it has been realized in HA Z tough steel.
- Figure 2 shows a steel plate made of 0.05% C—0.15% S i-1. 7 to 2.7% M n steel with 20 kg vacuum melting.
- CT OD test was conducted by applying the thermal history of the actual welded joint three times with a reproducible thermal cycle device.
- ⁇ ⁇ c 0. 1 (6 7 0. 9 C e ⁇ -6 7. 6) is the temperature at which the minimum value of the three CTO D test values is 0.1 mm at each test temperature. It is clear that TS c 0.1 (C TOD characteristics) tends to improve almost linearly as e H decreases. It can be seen that T ⁇ 5 c 0. 1 reaches 1600 ° C when C e H decreases to about 0.0 1.
- M n is an inexpensive element that has a large effect on optimizing the Miku mouth structure, and because it lowers CeH, it does not impair the HAZ toughness of small to medium heat input, so it is intended to increase the strength. It is preferable to increase the content. However, if it exceeds 2.7%, segregation of the slab is promoted, and it is easy to generate Bu harmful to toughness. Therefore, the upper limit is 2.7%. Also, since the effect is small at less than 1.7%, the lower limit was set at 1.7%. In addition, from the viewpoint of toughness, it is more preferable to exceed 2.0%.
- P and S should be less in terms of base material toughness and HAZ toughness, but the reduction is also due to industrial production constraints. 0.0 1 5%, 0.0 1 0%, preferably 0 The upper limit was 0 0 8 '% and 0. 0 0 5%.
- a 1 is not intentionally added in the present invention, but it cannot be avoided that it is mixed into the steel as an impurity. A smaller amount is preferable because it forms an A 1 oxide and inhibits the generation of T i oxide, but the reduction is limited in terms of industrial production, and 0.04% is the upper limit.
- T i greatly contributes to the improvement of toughness by generating Ti oxide and making the microstructure finer.
- 0 0 5 to 0. 0 1 5% is the appropriate range.
- O is necessary for the mass production of Ti oxides, and if less than 0.0 0 10%, the effect is small, while if it exceeds 0.0 04.5%, coarse Ti oxides are produced and the toughness is extremely deteriorated. Therefore, the content range was set to 0.0 0 1 0—0.0 04 5%.
- N is necessary to improve the base metal toughness and HAZ toughness by forming fine Ti nitrides.
- N is less effective if it is less than 0.02%, and steel is more than 0.06%.
- the upper limit was set to 0.0 0 6% because surface flaws occurred during the production of the piece.
- Nb and V are essentially embrittlement elements, and as shown by the large coefficient in equation (A), their presence greatly increases Ce H and significantly reduces HA Z toughness. Not intentionally added. Even when mixed into steel as an impurity, Nb must be limited to 0.0 3% or less to ensure toughness. V should be limited to 0.0 30% or less, preferably 0.0 20% or less.
- Cu and Ni have little HAZ toughness deterioration due to addition and have the effect of improving the strength of the base metal, which is effective for further improvement of properties.However, in order to increase the manufacturing cost, the content of the additive when added The upper limit was set to Cu: 0.25% and Ni: 0. '50%.
- the steel of the present invention is industrially desirably produced by a continuous forging method.
- the reason is that the solidification cooling rate of the molten steel is fast, and a large amount of fine Ti oxide and Ti nitride can be generated in the slab.
- the reheating temperature should be 1 100 and below. This is because when the reheating temperature exceeds 1100 ° C, the Ti nitride becomes coarse, and the toughness deterioration of the base metal and the HAZ toughness improvement effect cannot be expected.
- the heat treatment is essential for the manufacturing method after reheating. The reason is that even though excellent HAZ toughness can be obtained, if the toughness of the base metal is inferior, it is insufficient as a steel material.
- thermomechanical treatment methods include 1) controlled rolling, 2) controlled rolling and accelerated cooling, and 3) direct quenching and tempering after rolling. Preferred methods are controlled rolling and accelerated cooling, and after rolling. It is a direct quenching and tempering method.
- said method is an example of the manufacturing method of this invention steel, and the manufacturing method of this invention steel is not limited to said method.
- Steel sheets manufactured according to the present invention (present steels 1 to 20) have a yield strength (YS) of 4 3 0 N / mm 2 or more, — 2 0, — 40 ° C, — 6 0 ⁇ CT OD values However, both showed good fracture toughness of 0.27 mm or more.
- the comparative steels 21 to 26 are inferior in strength and C TOD values to the steels of the present invention, and do not have the characteristics required for steel sheets used in harsh environments.
- Comparative Steel 21 had a low CTOD value because Nb was added and the Nb content of the steel sheet was too high and the CeH value was also high. Since comparative steel 2 2 has too much C content and too much C e H, C T ⁇ D value was low. In Comparative Steels 2 3 and 2.4, CeH was low, but the A 1 content was too high, Ti oxide was not sufficiently generated, and the structure of the mouth was insufficient.
- Comparative Steel 25 CeH is similar to that of the invented steel, but C is too low and O is too much, so the base metal strength is low and the CTOD value is also low.
- Comparative Steel 26 the amount of Nb mixed in as an impurity was excessive, so that the base metal strength and CTOD value were both low despite the low CeH.
- Thermomechanical processing CR controlled rolling (rolling in a temperature range optimal for strength and toughness)
- the steel produced according to the present invention has high strength and excellent toughness with extremely good C T O D characteristics of the FL part where the toughness deteriorates most during welding. This made it possible to produce high-strength steel materials used in harsh environments such as offshore structures and earthquake-resistant buildings.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
Description
Claims
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP06843367A EP2060643B1 (en) | 2006-12-20 | 2006-12-20 | Steel excelling in toughness at region affected by welding heat |
CN200680006614A CN100594250C (zh) | 2006-12-20 | 2006-12-20 | 焊接热影响区的韧性优良的钢 |
CA2602076A CA2602076C (en) | 2006-12-20 | 2006-12-20 | Steel excellent in toughness of weld heat affected zone |
BRPI0607524A BRPI0607524B1 (pt) | 2006-12-20 | 2006-12-20 | aço e método de sua produção |
KR1020077019771A KR100940617B1 (ko) | 2006-12-20 | 2006-12-20 | 용접 열영향부의 인성이 우수한 강 |
PCT/JP2006/325984 WO2008075443A1 (ja) | 2006-12-20 | 2006-12-20 | 溶接熱影響部の靭性に優れた鋼 |
NO20074370A NO343351B1 (no) | 2006-12-20 | 2007-08-28 | Stål med utmerket seighet i sveisevarmepåvirket sveisesone og fremgangsmåte for fremstilling derav |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2006/325984 WO2008075443A1 (ja) | 2006-12-20 | 2006-12-20 | 溶接熱影響部の靭性に優れた鋼 |
Publications (1)
Publication Number | Publication Date |
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WO2008075443A1 true WO2008075443A1 (ja) | 2008-06-26 |
Family
ID=39536082
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2006/325984 WO2008075443A1 (ja) | 2006-12-20 | 2006-12-20 | 溶接熱影響部の靭性に優れた鋼 |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP2060643B1 (ja) |
KR (1) | KR100940617B1 (ja) |
CN (1) | CN100594250C (ja) |
BR (1) | BRPI0607524B1 (ja) |
CA (1) | CA2602076C (ja) |
WO (1) | WO2008075443A1 (ja) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008169429A (ja) * | 2007-01-11 | 2008-07-24 | Nippon Steel Corp | 溶接熱影響部のctodが優れた鋼およびその製造方法 |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2218800B1 (en) | 2007-12-07 | 2012-05-16 | Nippon Steel Corporation | Steel with weld heat-affected zone having excellent ctod properties and process for producing the steel |
US8668784B2 (en) | 2009-05-19 | 2014-03-11 | Nippon Steel & Sumitomo Metal Corporation | Steel for welded structure and producing method thereof |
TWI365915B (en) * | 2009-05-21 | 2012-06-11 | Nippon Steel Corp | Steel for welded structure and producing method thereof |
KR101360737B1 (ko) | 2009-12-28 | 2014-02-07 | 주식회사 포스코 | 취성 균열 발생 저항성이 우수한 고강도 강판 및 그 제조방법 |
JP2011246804A (ja) * | 2010-04-30 | 2011-12-08 | Nippon Steel Corp | 電子ビーム溶接継手及び電子ビーム溶接用鋼材とその製造方法 |
US9403242B2 (en) | 2011-03-24 | 2016-08-02 | Nippon Steel & Sumitomo Metal Corporation | Steel for welding |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000080437A (ja) * | 1998-04-17 | 2000-03-21 | Nippon Steel Corp | 溶接熱影響部の靱性に優れた鋼板 |
JP2006124759A (ja) * | 2004-10-27 | 2006-05-18 | Kobe Steel Ltd | 大入熱溶接継手靭性に優れた厚鋼板 |
JP2007002271A (ja) * | 2005-06-21 | 2007-01-11 | Nippon Steel Corp | 溶接熱影響部の破壊靭性に優れた鋼及びその製造方法 |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS624826A (ja) * | 1985-07-01 | 1987-01-10 | Kobe Steel Ltd | 不安定延性破壊伝播停止特性にすぐれた高強度高靭性ラインパイプ用鋼板の製造方法 |
JPH093597A (ja) * | 1995-06-21 | 1997-01-07 | Nippon Steel Corp | 溶接熱影響部靱性の優れた低温用鋼材およびその製造方法 |
CA2231985C (en) * | 1997-03-26 | 2004-05-25 | Sumitomo Metal Industries, Ltd. | Welded high-strength steel structures and methods of manufacturing the same |
JP4268317B2 (ja) * | 2000-06-09 | 2009-05-27 | 新日本製鐵株式会社 | 溶接部の低温靱性に優れた超高強度鋼管及びその製造方法 |
-
2006
- 2006-12-20 CN CN200680006614A patent/CN100594250C/zh active Active
- 2006-12-20 EP EP06843367A patent/EP2060643B1/en active Active
- 2006-12-20 BR BRPI0607524A patent/BRPI0607524B1/pt active IP Right Grant
- 2006-12-20 KR KR1020077019771A patent/KR100940617B1/ko active IP Right Grant
- 2006-12-20 CA CA2602076A patent/CA2602076C/en active Active
- 2006-12-20 WO PCT/JP2006/325984 patent/WO2008075443A1/ja active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000080437A (ja) * | 1998-04-17 | 2000-03-21 | Nippon Steel Corp | 溶接熱影響部の靱性に優れた鋼板 |
JP2006124759A (ja) * | 2004-10-27 | 2006-05-18 | Kobe Steel Ltd | 大入熱溶接継手靭性に優れた厚鋼板 |
JP2007002271A (ja) * | 2005-06-21 | 2007-01-11 | Nippon Steel Corp | 溶接熱影響部の破壊靭性に優れた鋼及びその製造方法 |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008169429A (ja) * | 2007-01-11 | 2008-07-24 | Nippon Steel Corp | 溶接熱影響部のctodが優れた鋼およびその製造方法 |
Also Published As
Publication number | Publication date |
---|---|
EP2060643A4 (en) | 2010-12-01 |
KR100940617B1 (ko) | 2010-02-05 |
CA2602076A1 (en) | 2008-06-20 |
KR20080067957A (ko) | 2008-07-22 |
CN100594250C (zh) | 2010-03-17 |
CA2602076C (en) | 2012-07-10 |
BRPI0607524A2 (pt) | 2010-03-23 |
EP2060643B1 (en) | 2012-04-18 |
EP2060643A1 (en) | 2009-05-20 |
CN101292055A (zh) | 2008-10-22 |
BRPI0607524B1 (pt) | 2016-01-19 |
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