CA2602076C - Steel excellent in toughness of weld heat affected zone - Google Patents
Steel excellent in toughness of weld heat affected zone Download PDFInfo
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- CA2602076C CA2602076C CA2602076A CA2602076A CA2602076C CA 2602076 C CA2602076 C CA 2602076C CA 2602076 A CA2602076 A CA 2602076A CA 2602076 A CA2602076 A CA 2602076A CA 2602076 C CA2602076 C CA 2602076C
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 62
- 239000010959 steel Substances 0.000 title claims abstract description 62
- 239000012535 impurity Substances 0.000 claims abstract description 11
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 11
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 8
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 8
- 229910052802 copper Inorganic materials 0.000 claims abstract description 7
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 7
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 7
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 4
- 229910052742 iron Inorganic materials 0.000 claims abstract description 3
- 239000004615 ingredient Substances 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims 1
- 239000000203 mixture Substances 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 17
- 230000000694 effects Effects 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 12
- 239000000463 material Substances 0.000 description 11
- 238000003466 welding Methods 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 7
- 238000001816 cooling Methods 0.000 description 7
- 238000005096 rolling process Methods 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 238000003303 reheating Methods 0.000 description 4
- 230000000930 thermomechanical effect Effects 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 238000004881 precipitation hardening Methods 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
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
-
- 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
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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
The present invention is a steel excellent in toughness of a weld heat affected zone characterized by containing, by mass%, C: 0.02 to 0.06%, Si: 0.05 to 0.30%, Mn: 1.7 to 2.7%, P: 0.015% or less, S: 0.010% or less, Ti: 0.005 to 0.015%, 0: 0.0010 to 0.0045, and N: 0.0020 to 0.0060% and comprising a balance of iron and unavoidable impurities, having an amount of intermixture of impurities limited to Al: 0.004% or less, Nb: 0.003% or less, and V: 0.030% or less, and having a CeH represented by formula (A) in the range of 0.04 or less: CeH = C+1/4Si-1/24Mn+1/48Cu+1/32Ni+1/0.4Nb+1/2V...(A) where, C, Si, Mn, Cu, Ni, Nb, and V show steel compositions (mass %) .
Description
DESCRIPTION
STEEL EXCELLENT IN TOUGHNESS OF WELD HEAT AFFECTED ZONE
TECHNICAL FIELD
The present invention relates to steel excellent in toughness of the weld heat affected zone (HAZ) in small heat input welding to medium heat input welding and a method of production thereof.
BACKGROUND ART
The HAZ toughness of a low alloy steel is governed by various factors such as (1) the size of the crystal grains, (2) the state of dispersion of hard phases such as high-carbon martensite (M*), upper bainite (Bu), and ferrite sideplate (FSP), (3) the state of precipitation hardening, (4) the presence of any intergranular embrittlement, and (5) the microsegregation of the elements. These factors are known to have a large effect on the toughness. Many technologies are being commercialized in order to improve the HAZ toughness.
It is safe to say that such toughness inhibiting factors are caused by additive elements. Reduction of the alloy element content increases the toughness. However, higher strength is always being sought in structural steel. Because of that, the addition of alloy elements is necessary. That is, the demands of strength and toughness are contradictory from the viewpoint of the alloy element content. Toughness increasing technology which does not depend on alloy elements has been sought.
As particularly excellent technology, it is known to use steel which does not substantially include any Al so as to make the microstructure finer and in addition correctly balance the Ti, 0, and N to suppress the precipitation of TiC and reduce precipitation hardening and thereby improve the toughness (Japanese Patent Publication (A) No. 5-247531). In this case, the toughness of the weld heat affected zone is determined by
STEEL EXCELLENT IN TOUGHNESS OF WELD HEAT AFFECTED ZONE
TECHNICAL FIELD
The present invention relates to steel excellent in toughness of the weld heat affected zone (HAZ) in small heat input welding to medium heat input welding and a method of production thereof.
BACKGROUND ART
The HAZ toughness of a low alloy steel is governed by various factors such as (1) the size of the crystal grains, (2) the state of dispersion of hard phases such as high-carbon martensite (M*), upper bainite (Bu), and ferrite sideplate (FSP), (3) the state of precipitation hardening, (4) the presence of any intergranular embrittlement, and (5) the microsegregation of the elements. These factors are known to have a large effect on the toughness. Many technologies are being commercialized in order to improve the HAZ toughness.
It is safe to say that such toughness inhibiting factors are caused by additive elements. Reduction of the alloy element content increases the toughness. However, higher strength is always being sought in structural steel. Because of that, the addition of alloy elements is necessary. That is, the demands of strength and toughness are contradictory from the viewpoint of the alloy element content. Toughness increasing technology which does not depend on alloy elements has been sought.
As particularly excellent technology, it is known to use steel which does not substantially include any Al so as to make the microstructure finer and in addition correctly balance the Ti, 0, and N to suppress the precipitation of TiC and reduce precipitation hardening and thereby improve the toughness (Japanese Patent Publication (A) No. 5-247531). In this case, the toughness of the weld heat affected zone is determined by
- 2 -the balance of the effects of the microstructure and the effects of the hardened layer which includes M*. In the prior art, this was solved by improving the toughness of the base material matrix by Ni and the like. However, the addition of large amounts of the Cu, Ni, and other expensive alloy elements necessary for the realization of this technology invited an increase in the production costs. This became an obstacle in producing high strength steel excellent in CTOD property.
The point of the steel according to this invention not substantially including any Al and Nb is made use of in the present invention as well. However, in this invention, the C content is high, so the problem of the drop in toughness when increasing the Mn content remains unsolved. Further, there was a concern over the impurities Nb and V having a detrimental effect on the toughness.
Further, Japanese Patent Publication (A) No. 2003-147484 follows the thinking of Japanese Patent Publication (A) No. No. 5-247531 and, while making use of Ti oxides, adds Nb and raises the Mn content. This causes the austenite-ferrite transformation start temperature to drop to thereby suppress the formation of the hard phases and simultaneously to obtain a suitable microstructure to thereby satisfy the -10 C CTOD property. However, the invention of this Japanese Patent Publication (A) No.
2003-147484 did not sufficiently satisfy the required CTOD property of weld joints at the much tougher level of -40 C or less.
DISCLOSURE OF THE INVENTION
The present invention provides technology which inexpensively produces high strength steel excellent in toughness in multi-layer welding of small to medium heat input. The steel produced by the present invention is extremely good in the CTOD property of multi-layer weld zones of small to medium heat input among the levels of weld heat affected zone toughness. The gist of the
The point of the steel according to this invention not substantially including any Al and Nb is made use of in the present invention as well. However, in this invention, the C content is high, so the problem of the drop in toughness when increasing the Mn content remains unsolved. Further, there was a concern over the impurities Nb and V having a detrimental effect on the toughness.
Further, Japanese Patent Publication (A) No. 2003-147484 follows the thinking of Japanese Patent Publication (A) No. No. 5-247531 and, while making use of Ti oxides, adds Nb and raises the Mn content. This causes the austenite-ferrite transformation start temperature to drop to thereby suppress the formation of the hard phases and simultaneously to obtain a suitable microstructure to thereby satisfy the -10 C CTOD property. However, the invention of this Japanese Patent Publication (A) No.
2003-147484 did not sufficiently satisfy the required CTOD property of weld joints at the much tougher level of -40 C or less.
DISCLOSURE OF THE INVENTION
The present invention provides technology which inexpensively produces high strength steel excellent in toughness in multi-layer welding of small to medium heat input. The steel produced by the present invention is extremely good in the CTOD property of multi-layer weld zones of small to medium heat input among the levels of weld heat affected zone toughness. The gist of the
- 3 -present invention is as follows.
(1) A steel excellent in toughness of a weld heat affected zone characterized by containing, by mass%, C:
0.02 to 0.06%, Si: 0.05 to 0.30%, Mn: 1.7 to 2.7%, P:
0.015% or less, S: 0.010% or less, Ti: 0.005 to 0.015%, 0: 0.0010 to 0.0045, and N: 0.0020 to 0.0060% and comprising a balance of iron and unavoidable impurities, having an amount of intermixture of impurities limited to Al: 0.004% or less, Nb: 0.003% or less, and V: 0.030% or less, and having a CeH represented by formula (A) in the range of 0.04 or less:
CeH = C+1/4Si-1/24Mn+1/48Cu+1/32Ni+1/0.4Nb+1/2V...(A) where, C, Si, Mn, Cu, Ni, Nb, and V show steel compositions (mass%).
(2) A steel excellent in toughness of a weld heat affected zone as set forth in (1), characterized in that the CeH is in the range of 0.01 or less.
(3) A steel excellent in toughness of a weld heat affected zone as set forth in (1) or (2), characterized by further containing, by mass%, one type or two types of Cu: 0.25% or less and Ni: 0.50% or less.
(1) A steel excellent in toughness of a weld heat affected zone characterized by containing, by mass%, C:
0.02 to 0.06%, Si: 0.05 to 0.30%, Mn: 1.7 to 2.7%, P:
0.015% or less, S: 0.010% or less, Ti: 0.005 to 0.015%, 0: 0.0010 to 0.0045, and N: 0.0020 to 0.0060% and comprising a balance of iron and unavoidable impurities, having an amount of intermixture of impurities limited to Al: 0.004% or less, Nb: 0.003% or less, and V: 0.030% or less, and having a CeH represented by formula (A) in the range of 0.04 or less:
CeH = C+1/4Si-1/24Mn+1/48Cu+1/32Ni+1/0.4Nb+1/2V...(A) where, C, Si, Mn, Cu, Ni, Nb, and V show steel compositions (mass%).
(2) A steel excellent in toughness of a weld heat affected zone as set forth in (1), characterized in that the CeH is in the range of 0.01 or less.
(3) A steel excellent in toughness of a weld heat affected zone as set forth in (1) or (2), characterized by further containing, by mass%, one type or two types of Cu: 0.25% or less and Ni: 0.50% or less.
(4) A method of production of steel excellent in toughness of a weld heat affected zone characterized by heating a slab satisfying the steel ingredients and CeH
of (1) or (g) to a temperature of 1100 C or less, then treating it by thermo-mechanical control process.
of (1) or (g) to a temperature of 1100 C or less, then treating it by thermo-mechanical control process.
(5) A method of production of steel excellent in toughness of a weld heat affected zone characterized by heating a slab satisfying the steel ingredients and CeH
of (3) to a temperature of 1100 C or less, then treating it by thermo-mechanical control process.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view showing the relationship of a cooling time of 800 to 500 C and an M* fraction.
FIG. 2 is a view showing the relationship of the CeH
and CTOD properties.
BEST MODE FOR CARRYING OUT THE INVENTION
According to the research of the present inventors, the CTOD property of the HAZ at the time of small to medium heating input (1.5 to 6.0 kJ/mm with a sheet thickness of 50 mm) welding (CTOD property at temperature of -40 C or less) is governed by the toughness of extremely local regions. Control of the microstructure of this portion and reduction of the embrittlement elements are important. In other words, the CTOD property is not the average property of the material, but is governed by the local embrittlement zones. If there are regions which cause embrittlement, even in just parts of the steel material, the CTOD property of the steel sheet will be remarkably impaired.
Specifically, the local regions which exert the greatest effects on the CTOD property are the M*, ferrite sideplate (FSP), and other hard phases. In order to suppress the formation of this kind of hard phase, in the past it had been necessary to keep the hardenability of the steel low. This became a factor inhibiting higher strength.
The present invention is characterized by the following discoveries and their embodiment in a steel of a high HAZ toughness. Specifically, 1) In a small to medium heat input welded HAZ, generally the cooling time after welding is within 60 seconds. The inventors discovered that under such cooling conditions, if the C content is sufficiently low, by adequately controlling other embrittlement elements, even if adding Mn to 27%, the M* which exerts a negative effect on toughness is no longer formed. FIG. 1 shows the M* fraction when changing the amount of.Mn from 1.7% to 2.7% with 0.05%C-0.15% Si. It is learned that even if the Mn content changes, if the cooling time of 800 to 500 C is within 60 seconds or so, the M* fraction becomes very small. As a result, it becomes possible to raise the content of Mn for which addition in a large quantity had been thought to be impossible in the past due to causing deterioration of the toughness.
2) The inventors discovered that the steel ingredients could be made suitable in an Al-less based steel.
3) The inventors eliminated the unexpected factors reducing toughness by limiting the Al, Nb, and V present as impurities in the steel to certain limits or less.
That is, by employing Al-less based steel, it became possible to reliably form TiO and effectively improve the toughness.
By combining these three points, it became possible to realize a good CTOD property under difficult temperature conditions of -20 C or less in a small to medium heat input welded HAZ which could not be achieved until now.
Even when very little M* is formed, control of the embrittlement elements C, Si, Cu, Ni, Nb, V, and the like is essential. Specifically, it is essential to control the value (CeH) of C+1/4Si-1/24Mn+1/48Cu+1/32Ni+1/0.4Nb+1/2V to a predetermined range.
FIG. 2 shows the results when producing 20 kg of steel of the steel ingredients of 0.05% C-0.15aSi-1.7 to 2.7%Mn by vacuum melting, rolling it to steel sheet, imparting a heat history of an actual welded joint three times by a simulated thermal cycle device, then running a CTOD test.
TSc 0.1 (670.9 CeH-67.6) is the temperature when the lowest value of three CTOD test values at different test temperatures is 0.1 mm. There is a clear trend for the TSc 0.1 (CTOD property) to excellent substantially linearly as the CeH drops. If the CeH drops to around 0.01, it is learned that the T8c 0.1 reaches -60 C.
That is, by satisfying the requirements of the
of (3) to a temperature of 1100 C or less, then treating it by thermo-mechanical control process.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view showing the relationship of a cooling time of 800 to 500 C and an M* fraction.
FIG. 2 is a view showing the relationship of the CeH
and CTOD properties.
BEST MODE FOR CARRYING OUT THE INVENTION
According to the research of the present inventors, the CTOD property of the HAZ at the time of small to medium heating input (1.5 to 6.0 kJ/mm with a sheet thickness of 50 mm) welding (CTOD property at temperature of -40 C or less) is governed by the toughness of extremely local regions. Control of the microstructure of this portion and reduction of the embrittlement elements are important. In other words, the CTOD property is not the average property of the material, but is governed by the local embrittlement zones. If there are regions which cause embrittlement, even in just parts of the steel material, the CTOD property of the steel sheet will be remarkably impaired.
Specifically, the local regions which exert the greatest effects on the CTOD property are the M*, ferrite sideplate (FSP), and other hard phases. In order to suppress the formation of this kind of hard phase, in the past it had been necessary to keep the hardenability of the steel low. This became a factor inhibiting higher strength.
The present invention is characterized by the following discoveries and their embodiment in a steel of a high HAZ toughness. Specifically, 1) In a small to medium heat input welded HAZ, generally the cooling time after welding is within 60 seconds. The inventors discovered that under such cooling conditions, if the C content is sufficiently low, by adequately controlling other embrittlement elements, even if adding Mn to 27%, the M* which exerts a negative effect on toughness is no longer formed. FIG. 1 shows the M* fraction when changing the amount of.Mn from 1.7% to 2.7% with 0.05%C-0.15% Si. It is learned that even if the Mn content changes, if the cooling time of 800 to 500 C is within 60 seconds or so, the M* fraction becomes very small. As a result, it becomes possible to raise the content of Mn for which addition in a large quantity had been thought to be impossible in the past due to causing deterioration of the toughness.
2) The inventors discovered that the steel ingredients could be made suitable in an Al-less based steel.
3) The inventors eliminated the unexpected factors reducing toughness by limiting the Al, Nb, and V present as impurities in the steel to certain limits or less.
That is, by employing Al-less based steel, it became possible to reliably form TiO and effectively improve the toughness.
By combining these three points, it became possible to realize a good CTOD property under difficult temperature conditions of -20 C or less in a small to medium heat input welded HAZ which could not be achieved until now.
Even when very little M* is formed, control of the embrittlement elements C, Si, Cu, Ni, Nb, V, and the like is essential. Specifically, it is essential to control the value (CeH) of C+1/4Si-1/24Mn+1/48Cu+1/32Ni+1/0.4Nb+1/2V to a predetermined range.
FIG. 2 shows the results when producing 20 kg of steel of the steel ingredients of 0.05% C-0.15aSi-1.7 to 2.7%Mn by vacuum melting, rolling it to steel sheet, imparting a heat history of an actual welded joint three times by a simulated thermal cycle device, then running a CTOD test.
TSc 0.1 (670.9 CeH-67.6) is the temperature when the lowest value of three CTOD test values at different test temperatures is 0.1 mm. There is a clear trend for the TSc 0.1 (CTOD property) to excellent substantially linearly as the CeH drops. If the CeH drops to around 0.01, it is learned that the T8c 0.1 reaches -60 C.
That is, by satisfying the requirements of the
- 6 -present invention steel and controlling the CeH, the intended CTOD property can be obtained. With the present invention steel, control of the value of CeH according to the required CTOD property is one of the characterizing features of the invention. In addition to the control of the value of CeH, rectifying the contents of the other alloy elements is required for realizing steel provided with both high strength and a superior CTOD property.
Below, the ranges of limitation and the reasons will be explained.
C has to be 0.02% or more in order to obtain strength, but if over 0.06%, it degrades the toughness of the welding HAZ and does not allow satisfaction of a good CTOD property, so 0.06% is made the upper limit.
Si inhibits the HAZ toughness, so a smaller amount is preferable in order to obtain a good HAZ toughness.
However, with the invention steel, no Al is added, so addition of 0.05% or more is necessary for deoxidation.
However, if the content is over 0.30%, the HAZ toughness is harmed, so 0.30% is made the upper limit.
Mn is an inexpensive element with a large effect of rectifying the microstructure and lowers the CeH, so addition does not harm the HAZ toughness of small to medium heat input, therefore it is desirable to make the content large to and obtain a high strength. However, if over 2.7%, it promotes the segregation of the slab and facilitates formation of Bu harmful to toughness, so the content was made to an upper limit of 2.7%. Further, if less than 1.7%, the effect is small, so the lower limit was made 1.7%. Note that from the viewpoint of toughness, over 2.0% is more preferable.
P and S should both be small in amount from the viewpoints of base material toughness and HAZ toughness, but there are limits to their reduction in industrial production. 0.015% and 0.010%, preferably 0.008% and 0.005%, were therefore made the upper limits.
Al is not deliberately added in the present
Below, the ranges of limitation and the reasons will be explained.
C has to be 0.02% or more in order to obtain strength, but if over 0.06%, it degrades the toughness of the welding HAZ and does not allow satisfaction of a good CTOD property, so 0.06% is made the upper limit.
Si inhibits the HAZ toughness, so a smaller amount is preferable in order to obtain a good HAZ toughness.
However, with the invention steel, no Al is added, so addition of 0.05% or more is necessary for deoxidation.
However, if the content is over 0.30%, the HAZ toughness is harmed, so 0.30% is made the upper limit.
Mn is an inexpensive element with a large effect of rectifying the microstructure and lowers the CeH, so addition does not harm the HAZ toughness of small to medium heat input, therefore it is desirable to make the content large to and obtain a high strength. However, if over 2.7%, it promotes the segregation of the slab and facilitates formation of Bu harmful to toughness, so the content was made to an upper limit of 2.7%. Further, if less than 1.7%, the effect is small, so the lower limit was made 1.7%. Note that from the viewpoint of toughness, over 2.0% is more preferable.
P and S should both be small in amount from the viewpoints of base material toughness and HAZ toughness, but there are limits to their reduction in industrial production. 0.015% and 0.010%, preferably 0.008% and 0.005%, were therefore made the upper limits.
Al is not deliberately added in the present
- 7 -invention, but inclusion as an impurity in the steel is unavoidable. This forms Al oxides which inhibit the formation of Ti oxides, so a smaller content is desirable, but there are limits to its reduction in industrial production. 0.004% is therefore the upper limit.
Ti forms Ti oxides and makes the microstructure finer, so greatly contributes to improvement of the toughness, but if the content is too great, it forms TiC.
This degrades the HAZ toughness, so 0.005 to 0.015% is a suitable range.
0 is necessary for the formation of a large amount of oxides of Ti. If less than 0.0010%, the effect is small, while if over 0.0045%, it forms coarse Ti oxides and sharply degrades the toughness, so the range of content was made 0.0010 to 0.0045%.
N is necessary to form fine Ti nitrides and improve the base material toughness and HAZ toughness, but if less than 0.002%, the effect is small, while if over 0.006%, surface defects are formed at the time of billet production, so the upper limit was made 0.006%.
Further, Nb and V are inherently embrittlement elements. As shown by the large coefficient in formula (A), their presence causes the CeH to greatly rise and made the HAZ toughness remarkably fall, so these are not deliberately added in the present invention. Even when included as impurities in the steel, to secure toughness, Nb has to be limited to 0.003% or less. Further, V has to be limited to 0.030% or less, preferably 0.020% or less.
Cu and Ni result in little deterioration of the HAZ
toughness due to their addition, have the effect of increasing the strength of the base material, and are effective for the further improvement of the properties, but increase the production costs, so the upper limits of the contents when added were made Cu: 0.25% and Ni:
0.500.
Even if limiting the ingredients of the steel in the
Ti forms Ti oxides and makes the microstructure finer, so greatly contributes to improvement of the toughness, but if the content is too great, it forms TiC.
This degrades the HAZ toughness, so 0.005 to 0.015% is a suitable range.
0 is necessary for the formation of a large amount of oxides of Ti. If less than 0.0010%, the effect is small, while if over 0.0045%, it forms coarse Ti oxides and sharply degrades the toughness, so the range of content was made 0.0010 to 0.0045%.
N is necessary to form fine Ti nitrides and improve the base material toughness and HAZ toughness, but if less than 0.002%, the effect is small, while if over 0.006%, surface defects are formed at the time of billet production, so the upper limit was made 0.006%.
Further, Nb and V are inherently embrittlement elements. As shown by the large coefficient in formula (A), their presence causes the CeH to greatly rise and made the HAZ toughness remarkably fall, so these are not deliberately added in the present invention. Even when included as impurities in the steel, to secure toughness, Nb has to be limited to 0.003% or less. Further, V has to be limited to 0.030% or less, preferably 0.020% or less.
Cu and Ni result in little deterioration of the HAZ
toughness due to their addition, have the effect of increasing the strength of the base material, and are effective for the further improvement of the properties, but increase the production costs, so the upper limits of the contents when added were made Cu: 0.25% and Ni:
0.500.
Even if limiting the ingredients of the steel in the
- 8 -above way, if not forming a suitable structure by a suitable method of production, the desired effects cannot be exhibited. Due to this, the production conditions also have to be considered.
The present invention steel is preferably produced industrially by continuous casting. The reasons are that the solidification cooling rate of the molten steel is fast and it is possible to form fine Ti oxides and Ti nitrides in large amounts in the slab. When rolling the slab, the reheating temperature has to be made 1100 C or less. If the reheating temperature exceeds 1100 C, the Ti nitrides becomes coarser, the toughness of the base material decreases, and the effect of improvement of the HAZ toughness cannot be expected.
Next, the method of production after reheating requires treatment by thermo-mechanical control process.
The reason is that even if a superior HAZ toughness is obtained, if the toughness of the base material is inferior, the steel product is insufficient. As methods of treatment by thermo-mechanical control process, 1) controlled rolling, 2) control rolling-accelerated cooling, 3) direct quenching-tempering after rolling, etc. can be mentioned, but the preferred methods are controlled rolling-accelerated cooling and the direct quenching-tempering after rolling.
Note that after producing the steel, even if reheating to a temperature of the Ar3 transformation point or more for the purpose of dehydrogenation etc., the characterizing features of the present invention are not impaired.
Further, the above method is one example of a method of production of the present invention steel. The method of production of the present invention steel is not limited to the above method.
EXAMPLES
Thick-gauge steel sheet of various steel ingredients were produced by the converter-continuous casting-thick-
The present invention steel is preferably produced industrially by continuous casting. The reasons are that the solidification cooling rate of the molten steel is fast and it is possible to form fine Ti oxides and Ti nitrides in large amounts in the slab. When rolling the slab, the reheating temperature has to be made 1100 C or less. If the reheating temperature exceeds 1100 C, the Ti nitrides becomes coarser, the toughness of the base material decreases, and the effect of improvement of the HAZ toughness cannot be expected.
Next, the method of production after reheating requires treatment by thermo-mechanical control process.
The reason is that even if a superior HAZ toughness is obtained, if the toughness of the base material is inferior, the steel product is insufficient. As methods of treatment by thermo-mechanical control process, 1) controlled rolling, 2) control rolling-accelerated cooling, 3) direct quenching-tempering after rolling, etc. can be mentioned, but the preferred methods are controlled rolling-accelerated cooling and the direct quenching-tempering after rolling.
Note that after producing the steel, even if reheating to a temperature of the Ar3 transformation point or more for the purpose of dehydrogenation etc., the characterizing features of the present invention are not impaired.
Further, the above method is one example of a method of production of the present invention steel. The method of production of the present invention steel is not limited to the above method.
EXAMPLES
Thick-gauge steel sheet of various steel ingredients were produced by the converter-continuous casting-thick-
- 9 -gauge sheet process. The base material strength was determined and a CTOD test of the weld joints was run.
The welding was performed by the submerged arc welding (SAW) method, generally used for test welding, with a welding heat input of 4.5 to 5.0 kJ/mm at the K groove so that the weld fusion line (FL) became perpendicular. The CTOD test was run by a sheet of a size of t (sheet thickness) x 2t notched by introducing a 50% fatigue crack in the FL location. Table 1 shows examples of the present invention and comparative examples.
The steel sheet produced by the present invention (Invention Steels 1 to 20) had yield strengths (YS) of 430 N/mm2 or more and exhibited good breaking toughness of CTOD values at -20 C, -40 C, and -60 C all of 0.27 mm or more.
As opposed to this, Comparative Steels 21 to 26 had strengths and CTOD values inferior to the invention steels and did not possess the properties necessary as steel sheet used under harsh environments. Comparative Steel 21 had Nb added, therefore the Nb content of the steel sheet became too great. The value of CeH also became high, so the CTOD value was a low value.
Comparative Steel 22 had too great a C content and also too great a value of CeH, so the CTOD value was a low value. Comparative Steels 23 and 24 had low CeH's, but the Al content was too high, Ti oxides were insufficiently formed, and the microstructure was not sufficiently made finer. Comparative Steel 25 had a CeH
of about the same extent as the invention steel, but the C was too low and the 0 was too great, so the base material strength was low and the CTOD value was a low value. Comparative Steel 26 had an excessively large amount of Nb mixed in as an impurity, so despite CeH
being low, the base material strength and CTOD value were low values.
The welding was performed by the submerged arc welding (SAW) method, generally used for test welding, with a welding heat input of 4.5 to 5.0 kJ/mm at the K groove so that the weld fusion line (FL) became perpendicular. The CTOD test was run by a sheet of a size of t (sheet thickness) x 2t notched by introducing a 50% fatigue crack in the FL location. Table 1 shows examples of the present invention and comparative examples.
The steel sheet produced by the present invention (Invention Steels 1 to 20) had yield strengths (YS) of 430 N/mm2 or more and exhibited good breaking toughness of CTOD values at -20 C, -40 C, and -60 C all of 0.27 mm or more.
As opposed to this, Comparative Steels 21 to 26 had strengths and CTOD values inferior to the invention steels and did not possess the properties necessary as steel sheet used under harsh environments. Comparative Steel 21 had Nb added, therefore the Nb content of the steel sheet became too great. The value of CeH also became high, so the CTOD value was a low value.
Comparative Steel 22 had too great a C content and also too great a value of CeH, so the CTOD value was a low value. Comparative Steels 23 and 24 had low CeH's, but the Al content was too high, Ti oxides were insufficiently formed, and the microstructure was not sufficiently made finer. Comparative Steel 25 had a CeH
of about the same extent as the invention steel, but the C was too low and the 0 was too great, so the base material strength was low and the CTOD value was a low value. Comparative Steel 26 had an excessively large amount of Nb mixed in as an impurity, so despite CeH
being low, the base material strength and CTOD value were low values.
- 10 -Ol r M~O .-1 .-/ 00 .--1 N ~O Ol V' N =-i M u) V' (N M M e=-I N N - N O O r O O IA Ol OD r C' N N aD O O
O O O O O O O O O O O O O O O O O N.-- N~-I N fM N O r-I
= O = O O = O O O O O O = O
Ql O O O O O O O O O O O O . O U I i I I I I I I I O= I 1 I O O I O O O O O O
O O I O
M~!) IO M ri r N M OD O OD N4 a0 if) M 10 N O N O OD a0 N N N N M N N("1 .N N
M N M N NN N N(') t+l -, M O N
O O O o O O O O O O O O O o O O O o O O O O o O O
O O O O O O O O O O O O O O O O O O O O O O O O O
O O O O O O O O O O O O O O O OO O O O O O O O O O
N tn c") L11 m l0 (D C~1 .-1 M f'1 u) LC).~ OO M N--I m~o M.-i .-I
r (=') M M C M = ('=1 M N f=1 = f=l M ' = m M M f='1 M
O O O O O O O O O O O O O O O O O O O O O O O O O
O O O O O O O O O O O O O O O O O O O O O O O O O
O O O. . . . . O O O O O O
c+'1 a= C7 N c'1 M C M N M M N(''1 M v f'l N M M N(V M c.-/ M M
O O O O O O O O O O O O O O O O O O O O O O N M O O
O O O O O O O O O O O O
. O O O. . O O O O O O O O O O O.
. . . . . . . . . . . . . . . . . . O.
~
Q,' O O O O O O O O O O O o O O O O O O O O O O O O O
0 m rl rl 01 . .-' 01 r-I rl N O M 00 O 01 1-1 0 Ol O O.-1 M - O O
r-I O r-1 r1 O O rl O r-I rl -4 '=I -4 O r-I 0 r-1 .-1 0 r-I -I -4 ri O V r-1 O. O. . O O O O O O O O. . . O O O O O O O O O O O O O O O O
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E O O O O O O O O O O O O O O O O O O O O. . O O O O o.
O
r-I
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O O O O O N O O O N O O O N O O O N.- O N
= O O = O = O O O
O O O O O = O O O= = O O O = O O O = O
> V V V V V O V V V O V V V O V V V O O V 0 .1 r-1 r-I r-1 ~i r-1 ~
.-i O
O O N M O r-I N O M.-1 O N ~O ~f) o~ h c O~ 0 O d' N~~-I =- O
= O O = O = O O = O = O O = O O = O O = O O O O O O
z v o o~'1v No v o.I of-Iv ON= V O
o = O = o = o o = = o o o V O O V O O= o V o 0 0 0 0 0 N c' O Ln N
C N M M
z o 0 0 0 0 a ln t!l M M
N =--~ ~-I N .-1 U o 0 o O o N M M N OD N M V= 'fl M r N."~ N.-i N f'9 OD N M - C' V' N V' Y' O O O. O O O O O O O O O O O O O O O O O O O O O O O
. . . . . . . . . . . . . . . . . . . .
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O O O O O O.-i O O O O'i O O O O O O O O O O O O O O
O O O O O O O O. . O O O O O O O O O O O O O O O O O O
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~O If) V' M M f~ N N.1 =-I O O~ 01 aD OD U~ r r r OD OD .=i .--1 N O
N N N N N N (A N N N N N=-~ .--I .--I =-I .--1 A .--1 4 1-4 -I N N N N
M 0 -N 01 .=-I N NLr) W rl O .1 O1 N r1 01 ('1 C' Nw.--~ m v' O .=-1 .--I .-~ .--1 O .-i ri r-1 .-I .-1 .--1 .-i .--1 .--~ .-i . . . . . . . . . . . . . . . . . . . . . .
.=.I
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1-=1 M N ul r-1 N~O r N O O f''1 V' Lfl m 00 0 a' h 'n .--1 V= t!) (''1 'D m N N N N(=')(='1 M M M V~ R~ V= V= C vC' N 1) v1 N ul 01 d' v rl d' O O O O O O O O O O O O O O O O O O O O O O O O O O
. . . . . . . . . . . . . . . . . . . . . .
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Ql O O O O O O O O O O O O . O U I i I I I I I I I O= I 1 I O O I O O O O O O
O O I O
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M N M N NN N N(') t+l -, M O N
O O O o O O O O O O O O O o O O O o O O O O o O O
O O O O O O O O O O O O O O O O O O O O O O O O O
O O O O O O O O O O O O O O O OO O O O O O O O O O
N tn c") L11 m l0 (D C~1 .-1 M f'1 u) LC).~ OO M N--I m~o M.-i .-I
r (=') M M C M = ('=1 M N f=1 = f=l M ' = m M M f='1 M
O O O O O O O O O O O O O O O O O O O O O O O O O
O O O O O O O O O O O O O O O O O O O O O O O O O
O O O. . . . . O O O O O O
c+'1 a= C7 N c'1 M C M N M M N(''1 M v f'l N M M N(V M c.-/ M M
O O O O O O O O O O O O O O O O O O O O O O N M O O
O O O O O O O O O O O O
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. . . . . . . . . . . . . . . . . . O.
~
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0 m rl rl 01 . .-' 01 r-I rl N O M 00 O 01 1-1 0 Ol O O.-1 M - O O
r-I O r-1 r1 O O rl O r-I rl -4 '=I -4 O r-I 0 r-1 .-1 0 r-I -I -4 ri O V r-1 O. O. . O O O O O O O O. . . O O O O O O O O O O O O O O O O
. . . . . . .
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O
r-I
r-1 1-1 rl rf 14 8 '-1 .-i r=1 -4 O O O O O O O O O u) O O O O O O O r ul O M
O O O O O N O O O N O O O N O O O N.- O N
= O O = O = O O O
O O O O O = O O O= = O O O = O O O = O
> V V V V V O V V V O V V V O V V V O O V 0 .1 r-1 r-I r-1 ~i r-1 ~
.-i O
O O N M O r-I N O M.-1 O N ~O ~f) o~ h c O~ 0 O d' N~~-I =- O
= O O = O = O O = O = O O = O O = O O = O O O O O O
z v o o~'1v No v o.I of-Iv ON= V O
o = O = o = o o = = o o o V O O V O O= o V o 0 0 0 0 0 N c' O Ln N
C N M M
z o 0 0 0 0 a ln t!l M M
N =--~ ~-I N .-1 U o 0 o O o N M M N OD N M V= 'fl M r N."~ N.-i N f'9 OD N M - C' V' N V' Y' O O O. O O O O O O O O O O O O O O O O O O O O O O O
. . . . . . . . . . . . . . . . . . . .
U) ID a= u) i() t0 N- t0 On U) 0 rkO c t0 l0 U) t0 - - OD r t0 - OD
O O O O O O.-i O O O O'i O O O O O O O O O O O O O O
O O O O O O O O. . O O O O O O O O O O O O O O O O O O
. . . . . . . . . . . . . . . . . . . 99 0 , o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o O O o 0 0 0 ~!) r r 01 00 o r m~ M~D M v' Ol r Lf) O- aD Ma) OD m.--I O O
~O If) V' M M f~ N N.1 =-I O O~ 01 aD OD U~ r r r OD OD .=i .--1 N O
N N N N N N (A N N N N N=-~ .--I .--I =-I .--1 A .--1 4 1-4 -I N N N N
M 0 -N 01 .=-I N NLr) W rl O .1 O1 N r1 01 ('1 C' Nw.--~ m v' O .=-1 .--I .-~ .--1 O .-i ri r-1 .-I .-1 .--1 .-i .--1 .--~ .-i . . . . . . . . . . . . . . . . . . . . . .
.=.I
V) O O O O O O O O. O. O O O O. O O 000 O O O O O O. O O
1-=1 M N ul r-1 N~O r N O O f''1 V' Lfl m 00 0 a' h 'n .--1 V= t!) (''1 'D m N N N N(=')(='1 M M M V~ R~ V= V= C vC' N 1) v1 N ul 01 d' v rl d' O O O O O O O O O O O O O O O O O O O O O O O O O O
. . . . . . . . . . . . . . . . . . . . . .
U O O O C. O O O O O O O O O O O 0 0 O O O O 0 0 O O O
~--I y O r-I N M C tn l0 r OD 01 O r-1 N f='7 a' ul 'O
(p .-1 N M C ul l0 I~ OD O~ .--1 r-I e--I .-- r1 r-1 r1 .-~ N N N N N N N
N U
i--~ ~
.~ W
E'I V1 H~.'~ = Cl X U 0 ~ I]. W X
- 11 -~
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O
N b ~ o rl W 1-1 mID ('1 Ol ao ko e-V l0 C O O] r Ifl V' ~ V' V' N tn C' C' M O .-I
~
o 0 0 0 0 o O o 0 0 0 0 0 0 o 4J
a-) q ~ U
{ m y~
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O C ~
ro t_-n o N 01 M r r O~n N v M~ aD O1 ~ U
r-1 O ~ V' ~n ~o M M v O O O O O 0 o g o 0 0 0 0 0 0 0 0 0 0 0 0 ~ ~
C C
l~ 10 0 tr ~
C C
Ol N o H m O
+1 C
N 4) N t1 0 N
tli ro H 0 .('. W O M M -4 O M OD N 01 N O~f1 Vl r N d' M OD .-~ r r~D (N M 01 -4 0 -,{
C ~I' V' r 1f) l0 lD L!) lfl M C' 10 10 O] Ol -4 N1f7 v' lO C C' rl lG N 44 CT
E+ ~-- 10 ~A V1 tn N ul Vl ~ u1 ln LA u Ln 1n ul kO V1 Lfl N u=I l0 if) C' 171 y --I H
ro 41 -.-1 H
~ 0 b H
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ro N o ~
m ''' v -,~ ,d ~ b+ U) a~
+, ro u H v W ~ a' (N O M Ul lf) -i r o N~ 01 V' 1f1 l0 w r ln l0 M O N- 01 f''1 H
.'F. Cl Lfl If1 t' 01 tD O1 r~O N C u 1 r ~O 01 01 M M ifl v' l0 C' M N r O M O
a. ?4 "-' ~n v~ m<r c c v~ c va c vc a c U-) a c vc In c c M r~ u H
H 4J 3 ~
a N rtf 0 =.i ~ H ro ro a x Ia, tDl 0 H U
a) -4 1~ i H
N r O G) J-) 0 L
a==) rt1 u 4-4 v 1, ro y O b) H
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O
" a v N ~ bl -H 41 ~ p ri 0 a ~ ~ r u .I
=
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ro x ro r H U! U U U U U U U U U U U U U U U U U U U U U U U 4' (D
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+s~aaoaaaaaaaavaaaaoaaaaaaaaa~~~
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b 4-1 u a) o a 0 cC =H
v U O
~~ f.. 11 U
tl r1 O
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T7 A R. o o 0 0 0 0 o 0 0 o 0 0 0 0 o 0 o o 0 0 o 0 0 o 0 o N
o ro ~LnLnooLn no~nooun Lnoun v~oLnouioLnooLnoo H.1 N O O.-i -1 O O.-1 O-1 --1 O O r-1 O O O O ri 0 -1 ~~~~~~ p a cn l) ,~ ,-1 ,~ 1-4 ,~ 1-1 1-4 1i ~ 1-4 .-~ ,~ r-V r-1 1-1 r-I r-I ,~ ri ,-4 r-I -, 1-4 1-4 ,~ .r., +-, ~
a ~
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ro O e--1 N M JJW r 40 T O~-1 N M V' N'D
H
.A [LLL JNICOICD .-/ 'i -I 14 H -I r-1 .--1 .-i r1 N N N N N N N
(N
m ai m .C
a) u o+
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N b ~ o rl W 1-1 mID ('1 Ol ao ko e-V l0 C O O] r Ifl V' ~ V' V' N tn C' C' M O .-I
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o 0 0 0 0 o O o 0 0 0 0 0 0 o 4J
a-) q ~ U
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ro t_-n o N 01 M r r O~n N v M~ aD O1 ~ U
r-1 O ~ V' ~n ~o M M v O O O O O 0 o g o 0 0 0 0 0 0 0 0 0 0 0 0 ~ ~
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l~ 10 0 tr ~
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Ol N o H m O
+1 C
N 4) N t1 0 N
tli ro H 0 .('. W O M M -4 O M OD N 01 N O~f1 Vl r N d' M OD .-~ r r~D (N M 01 -4 0 -,{
C ~I' V' r 1f) l0 lD L!) lfl M C' 10 10 O] Ol -4 N1f7 v' lO C C' rl lG N 44 CT
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a. ?4 "-' ~n v~ m<r c c v~ c va c vc a c U-) a c vc In c c M r~ u H
H 4J 3 ~
a N rtf 0 =.i ~ H ro ro a x Ia, tDl 0 H U
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- 12 -INDUSTRIAL APPLICABILITY
The steel produced by the present invention is high in strength, has an extremely good CTOD property of the FL part where the toughness degrades the most at the time of welding, and exhibits superior toughness. Due to this, production of a high strength steel product that can be used in offshore structures, earthquake resistant buildings, and other harsh environments became possible.
The steel produced by the present invention is high in strength, has an extremely good CTOD property of the FL part where the toughness degrades the most at the time of welding, and exhibits superior toughness. Due to this, production of a high strength steel product that can be used in offshore structures, earthquake resistant buildings, and other harsh environments became possible.
Claims (3)
1. A steel excellent in toughness of a weld heat affected zone characterized by containing, by mass%, C:0.02 to 0.06%, Si:0.05 to 0.30%, Mn:l.7 to 2.7%, P:0.015% or less, S:0.0100 or less, Ti:0.005 to 0.015%, 0:0.0010 to 0.0045%, N:0.0020 to 0.0060%, Cu:0.25% or less, and Ni:0.50% or less, and comprising a balance of iron and unavoidable impurities, having an amount of intermixture of impurities limited to Al:0.004% or less, Nb:0.003% or less, and V:0.030% or less, and having a CeH
represented by formula (A) in the range of 0.04 or less:
CeH = C+1/4Si-1/24Mn+1/48Cu+1/32Ni+1/0.4Nb+1/2V...(A) wherein, C, Si, Mn, Cu, Ni, Nb, and V show steel ingredients (mass%).
represented by formula (A) in the range of 0.04 or less:
CeH = C+1/4Si-1/24Mn+1/48Cu+1/32Ni+1/0.4Nb+1/2V...(A) wherein, C, Si, Mn, Cu, Ni, Nb, and V show steel ingredients (mass%).
2. A steel excellent in toughness of a weld heat affected zone as set forth in claim 1, characterized in that the CeH is in the range of 0.01 or less.
3. A steel excellent in toughness of a weld heat affected zone as set forth in claim 1 or 2, characterized by further containing, by mass%, one type or two types of Cu: 0.25% or less and Ni: 0.50% or less.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP2006/325984 WO2008075443A1 (en) | 2006-12-20 | 2006-12-20 | Steel excelling in toughness at region affected by welding heat |
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| Publication Number | Publication Date |
|---|---|
| CA2602076A1 CA2602076A1 (en) | 2008-06-20 |
| CA2602076C true CA2602076C (en) | 2012-07-10 |
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| CA2602076A Active CA2602076C (en) | 2006-12-20 | 2006-12-20 | Steel excellent in toughness of weld heat affected zone |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP2060643B1 (en) |
| KR (1) | KR100940617B1 (en) |
| CN (1) | CN100594250C (en) |
| BR (1) | BRPI0607524B1 (en) |
| CA (1) | CA2602076C (en) |
| WO (1) | WO2008075443A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4751341B2 (en) * | 2007-01-11 | 2011-08-17 | 新日本製鐵株式会社 | Steel excellent in CTOD of weld heat affected zone and method for producing the same |
| 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 (en) | 2009-12-28 | 2014-02-07 | 주식회사 포스코 | High strength steel plate having excellent resistance to brittle crack initiation and method for manufacturing the same |
| JP2011246804A (en) * | 2010-04-30 | 2011-12-08 | Nippon Steel Corp | Electronic-beam welding joint and steel for electronic-beam welding, and manufacturing method therefor |
| US9403242B2 (en) | 2011-03-24 | 2016-08-02 | Nippon Steel & Sumitomo Metal Corporation | Steel for welding |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS624826A (en) * | 1985-07-01 | 1987-01-10 | Kobe Steel Ltd | Manufacture of high strength and toughness steel plate for line pipe superior in characteristic for stopping unstable ductility fracture propagation |
| JPH093597A (en) * | 1995-06-21 | 1997-01-07 | Nippon Steel Corp | Steel for low temperature use excellent in toughness of weld heat affected zone and its production |
| CA2231985C (en) * | 1997-03-26 | 2004-05-25 | Sumitomo Metal Industries, Ltd. | Welded high-strength steel structures and methods of manufacturing the same |
| JP3522564B2 (en) * | 1998-04-17 | 2004-04-26 | 新日本製鐵株式会社 | Steel plate with excellent toughness in weld heat affected zone |
| JP4268317B2 (en) * | 2000-06-09 | 2009-05-27 | 新日本製鐵株式会社 | Ultra-high-strength steel pipe excellent in low temperature toughness of welded portion and manufacturing method thereof |
| JP4311740B2 (en) * | 2004-10-27 | 2009-08-12 | 株式会社神戸製鋼所 | Thick steel plate with high heat input welded joint toughness |
| JP4303703B2 (en) * | 2005-06-21 | 2009-07-29 | 新日本製鐵株式会社 | Steel excellent in fracture toughness of weld heat affected zone and method for producing the same |
-
2006
- 2006-12-20 CN CN200680006614A patent/CN100594250C/en active Active
- 2006-12-20 EP EP06843367A patent/EP2060643B1/en active Active
- 2006-12-20 BR BRPI0607524A patent/BRPI0607524B1/en active IP Right Grant
- 2006-12-20 KR KR1020077019771A patent/KR100940617B1/en active IP Right Grant
- 2006-12-20 CA CA2602076A patent/CA2602076C/en active Active
- 2006-12-20 WO PCT/JP2006/325984 patent/WO2008075443A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| EP2060643A4 (en) | 2010-12-01 |
| KR100940617B1 (en) | 2010-02-05 |
| CA2602076A1 (en) | 2008-06-20 |
| KR20080067957A (en) | 2008-07-22 |
| CN100594250C (en) | 2010-03-17 |
| WO2008075443A1 (en) | 2008-06-26 |
| BRPI0607524A2 (en) | 2010-03-23 |
| EP2060643B1 (en) | 2012-04-18 |
| EP2060643A1 (en) | 2009-05-20 |
| CN101292055A (en) | 2008-10-22 |
| BRPI0607524B1 (en) | 2016-01-19 |
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