WO2010032428A1 - 高強度厚鋼板およびその製造方法 - Google Patents
高強度厚鋼板およびその製造方法 Download PDFInfo
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- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
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- 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
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- 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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
Definitions
- the present invention is used for structural members of construction machinery and industrial machinery, and has excellent delayed fracture resistance, bending workability and weldability, high strength with yield strength of 1300 MPa or more and tensile strength of 1400 MPa or more, and plate thickness of 4.5 mm or more.
- the present invention relates to a high-strength thick steel plate that is 25 mm or less and a method for producing the same.
- Patent Document 1 discloses a method for producing a steel plate having a tensile strength of 1370 to 1960 N / mm 2 and excellent hydrogen embrittlement resistance. Yes.
- the technique of Patent Document 1 relates to a cold-rolled steel sheet having a thickness of 1.8 mm, and is premised on a high cooling rate of 70 ° C./sec or higher, and no consideration is given to weldability.
- Patent documents 2 and 3 are examples of the technology.
- the prior austenite crystal grain size needs to be 5 ⁇ m or less (Patent Document 2) to 7 ⁇ m or less (Patent Document 3).
- Patent Document 2 and Patent Document 3 are both techniques for refining the prior austenite crystal grain size by rapid heating before quenching.
- special heating equipment is required, so that the technology is difficult to realize.
- hardenability is reduced as crystal grains are refined, an extra alloy element is required to ensure strength. Therefore, excessive grain refinement is not preferable from the viewpoints of weldability and economy.
- Patent Document 4 and Patent Document 5 disclose wear-resistant steel having excellent delayed fracture resistance.
- the tensile strengths of Patent Document 4 and Patent Document 5 are 1400 MPa to 1500 MPa and 1450 MPa to 1600 MPa, respectively.
- neither Patent Document 4 nor Patent Document 5 describes the yield stress. Since hardness is an important factor for wear resistance, tensile strength affects wear resistance. However, since the yield strength does not significantly affect the wear resistance, the yield strength is usually not considered in the wear resistant steel. Therefore, it is thought that it is not suitable as a structural member for construction machinery or industrial machinery.
- Patent Document 6 improves the delayed fracture resistance of high-strength bolt steel materials with a yield strength of 1300 MPa class by elongation of prior austenite grains and rapid heating and tempering. However, since rapid heating and tempering is difficult with normal thick plate heat treatment equipment, application to thick steel plates is difficult.
- JP-A-7-90488 Japanese Patent Laid-Open No. 11-80903 JP 2007-302974 A JP-A-11-229075 Japanese Unexamined Patent Publication No. 1-149921 JP-A-9-263876
- An object of the present invention is to provide a high-strength thick steel plate for a structural member having a delayed fracture resistance, bending workability and weldability excellent in delayed fracture resistance, bending workability and weldability, and a tensile strength of 1400 MPa or more, which are used for structural members of construction machinery and industrial machinery. Is to provide a method.
- the most economical means for obtaining a high strength with a yield strength of 1300 MPa or more and a tensile strength of 1400 MPa or more is to make the steel material structure martensite by quenching heat treatment from a constant temperature.
- the hardenability and cooling rate of the steel must be appropriate.
- the plate thickness of thick steel plates used as structural members for construction machines and industrial machines is mostly 25 mm or less.
- the average cooling rate at the center of the plate thickness is 20 ° C./sec or more under water cooling conditions with a water density of about 1 m 3 / m 2 ⁇ min during quenching heat treatment using a normal steel plate cooling facility. is there.
- the martensite structure in the present invention is a structure that is considered to be substantially full martensite after quenching. Specifically, the martensite structure fraction is 90% or more, and the structure fraction other than martensite such as retained austenite, ferrite, and bainite is less than 10%. When the martensite structure fraction is low, an extra alloy element is required to obtain a certain strength.
- the inventor has developed y-type welding as defined in JIS Z 3158 for various steel sheets having a plate thickness of 25 mm, a prior austenite grain size number of 8 to 11, a yield strength of 1300 MPa or more and a tensile strength of 1400 MPa or more.
- a crack test was carried out to investigate the relationship between the weld crack sensitivity index Pcm and the preheating temperature. The result is shown in FIG. In order to reduce the welding load, it is desirable that the preheating temperature is as low as possible.
- the crack stop preheating temperature that is, the preheating temperature at which the root crack rate becomes 0 is set to 150 ° C. or less.
- the Pcm for the root crack rate to be completely 0 at a preheating temperature of 150 ° C. is 0.36% or less, and this Pcm was used as a guideline for the upper limit of the alloy addition amount.
- the weld crack is greatly influenced by the preheating temperature, and FIG. 1 shows the relationship between the weld crack and the preheating temperature.
- Pcm needs to be 0.36% or less.
- Pcm needs to be 0.34% or less.
- the delayed fracture resistance of martensitic steel is highly dependent on strength. If the tensile strength exceeds 1200 MPa, delayed fracture may occur. Furthermore, the sensitivity to delayed fracture increases as the strength increases.
- As a means for improving the delayed fracture resistance of martensitic steel there is a method of refining the prior austenite grain size as described above. However, since the hardenability decreases as the crystal grains become finer, a larger amount of alloy element is required to ensure the strength. Therefore, excessive crystal grain refinement is not preferable from the viewpoints of weldability and economy.
- the inventor examined in detail the influence of steel sheet strength, particularly tensile strength, and prior austenite grain size on delayed fracture resistance of martensitic steel. As a result, by controlling the tensile strength and the prior austenite grain size within a certain range, both the delayed fracture resistance and sufficient hardenability to ensure a martensite structure under the condition of suppressing the amount of alloying elements are achieved. I found out that I can do it. The specific control range will be described below.
- the delayed fracture resistance was evaluated by the “limit diffusible hydrogen content” which is the upper limit of the hydrogen content that does not break in the delayed fracture test. This method is disclosed in Iron and Steel, Vol. 83 (1997), p454. Specifically, after adding various amounts of diffusible hydrogen to a sample with a notch having the shape shown in FIG. 2 by round bar electrolytic hydrogen charging, the surface of the sample is plated to remove hydrogen. The scattering was prevented. The test piece was held under a predetermined load in the atmosphere, and the time until delayed fracture occurred was measured. The load stress in the delayed fracture test was 0.8 times the tensile strength of each steel material.
- FIG. 3 is an example of the relationship between the amount of diffusible hydrogen and the fracture time until delayed fracture.
- the time until delayed fracture increases. Also, if the amount of diffusible hydrogen is below a certain value, delayed fracture will not occur.
- the integrated value of the hydrogen amount measured by collecting the test piece immediately after the test and raising the temperature to 400 ° C. under a temperature rising condition of 100 ° C./hr by a gas chromatograph is defined as “diffusible hydrogen amount”. Further, the limit amount of hydrogen at which the test piece does not break is defined as “limit diffusible hydrogen amount Hc”.
- the amount of hydrogen that enters the steel from the environment also varies depending on the metallurgical factors of the steel.
- a corrosion acceleration test was conducted. In this test, a 5 mass% NaCl solution is used for 30 days in the cycle shown in FIG. After the test, the amount of hydrogen that has penetrated into the steel material is defined as “the amount of diffusible hydrogen that intrudes from the environment HE” as the integral value of the amount of hydrogen measured using a gas chromatograph under the same temperature rise conditions as the measurement of diffusible hydrogen. .
- the delayed fracture susceptibility is considered to be low.
- Hc / HE is greater than 3, it is evaluated that delayed fracture susceptibility is low and delayed fracture resistance is good.
- the prior austenite grain size was evaluated by the prior austenite grain size number.
- the result is shown in FIG. In FIG. 5, Hc / HE> 3 is indicated by ⁇ , and Hc / HE ⁇ 3 is indicated by ⁇ . From FIG. 5, it can be seen that delayed fracture susceptibility is well organized by tensile strength and prior austenite grain number (N ⁇ ). That is, it is shown that the delayed fracture resistance can be reliably improved by controlling the tensile strength and the prior austenite grain size together.
- miniaturization is effective in reducing delayed fracture susceptibility.
- the hardenability is lowered, and it becomes difficult to obtain a martensite structure (martensite). Therefore, more alloy elements are required to obtain a predetermined strength.
- the upper limit of Pcm is regulated from the viewpoint of ensuring the above-described weldability, when the austenite particle size is excessively refined, it is difficult to obtain martensite at this cooling rate.
- the inventor conducted various investigations on the relationship between the alloy amount, the prior austenite grain size, and the strength.
- the upper limit of the tensile strength is set to 1650 MPa.
- the strength of martensitic steel is greatly affected by the C content and the tempering temperature. Therefore, in order to obtain a yield strength of 1300 MPa or more and a tensile strength of 1400 MPa or more and 1650 MPa or less, it is necessary to appropriately select the amount of C and the tempering temperature. 6 and 7 show the influence of the C content and the tempering temperature on the yield strength and tensile strength of martensitic steel, respectively.
- the tempering heat treatment is not performed, that is, in the as-quenched state, the yield ratio of the martensite structure is low. Therefore, the tensile strength is high, but the yield strength is low.
- the C content needs to be about 0.24% or more.
- the inventor can easily and stably obtain polygonal sizing of the prior austenite grain size number satisfying the above (a) and (b) by the following production method.
- I got the knowledge that I can. That is, an appropriate amount of Nb is added to the steel sheet, and an appropriate controlled rolling is performed during hot rolling to introduce an appropriate working strain to the steel sheet before quenching. Thereafter, reheating and quenching is performed in a range where the reheating temperature is in the range of Ac3 transformation point + 20 ° C.
- FIG. 8 shows an example of the relationship between the quenching heating temperature (reheating temperature) and the prior austenite grain size. It should be noted that refinement of prior austenite is also effective for the bending workability of the steel sheet, and if the tensile strength and the prior austenite grain size number are within the scope of the present invention, good bendability is obtained.
- a steel plate having a yield strength of 1300 MPa or more and a tensile strength of 1400 MPa or more (preferably 1400 to 1650 MPa) and a thickness of 4.5 mm to 25 mm excellent in delayed fracture resistance, bending workability, and weldability is obtained. be able to.
- the gist of the present invention is as follows. (1) By mass%, C: 0.18% or more, 0.23% or less, Si: 0.1% or more, 0.5% or less, Mn: 1.0% or more, 2.0% or less, P : 0.020% or less, S: 0.010% or less, Ni: 0.5% or more, 3.0% or less, Nb: 0.003% or more, 0.10% or less, Al: 0.05% or more 0.15% or less, B: 0.0003% or more, 0.0030% or less, N: 0.006% or less, the balance being Fe and inevitable impurities, and [C], [Si], [Mn], [Cu], [Ni], [Cr], [Mo], [V], [B] are the concentrations of C, Si, Mn, Cu, Ni, Cr, Mo, V, and B, respectively.
- Pcm [C] + [Si] / 30 + [Mn] / 20 + [Cu] / 20 + [Ni] / 60 + [Cr] / 20 + [Mo / 15 + [V] / 10 + 5 [B] weld crack susceptibility index Pcm calculated by having a component composition that meets the at most 0.36%; A c3 transformation point is at 830 ° C. or less, martensite The fraction is 90% or more, the yield strength is 1300 MPa or more, the tensile strength is 1400 MPa or more and 1650 MPa or less, and furthermore, using the tensile strength and the average number of crystal grains m per 1 mm 2 of the sample piece cross section.
- N ⁇ ⁇ 3 + log 2 m and the former austenite grain size number N ⁇ , when the tensile strength is [TS] (MPa) and the tensile strength is less than 1550 MPa, N ⁇ ⁇ ([TS] ⁇ 1400) ⁇ 0.004 + 8.0, N ⁇ ⁇ 11.0 is satisfied, and when the tensile strength is 1550 MPa or more, N ⁇ ⁇ ([TS] ⁇ 1550) 0.008 + 8.6, and satisfies the N ⁇ ⁇ 11.0; high strength steel plate, characterized in that.
- the plate thickness may be 4.5 mm or more and 25 mm or less.
- a steel slab or cast slab having the composition described in (1) or (2) above is heated to 1100 ° C. or higher; 930 ° C. so that the steel sheet has a thickness of 4.5 mm or more and 25 mm or less.
- hot rolling is performed in which the cumulative rolling reduction in the temperature range of 860 ° C. or higher is 30% or more and 65% or less and the rolling is finished at 860 ° C. or higher; after cooling, the steel sheet is subjected to Ac 3 transformation point + 20 ° C. Then, reheating to a temperature of 850 ° C. or lower; thereafter, accelerated cooling to 200 ° C. or lower under cooling conditions in which the average cooling rate at the plate thickness center portion of the steel sheet from 600 ° C.
- 300 ° C. is 20 ° C./sec or higher. And then performing a tempering heat treatment in a temperature range of 200 ° C. or higher and 300 ° C. or lower; and a method for producing a high-strength thick steel plate.
- a thick steel plate having a yield strength of 1300 MPa or more and a tensile strength of 1400 MPa or more, which is excellent in delayed fracture resistance, bending workability and weldability, used for a structural member of a construction machine or industrial machine. Can do.
- C is an important element that greatly affects the strength of the martensite structure.
- the C content is determined as an amount necessary for obtaining a yield strength of 1300 MPa or more and a tensile strength of 1400 MPa or more and 1650 MPa or less when the martensite structure fraction is 90% or more.
- the range of C content is 0.18% or more and 0.23% or less.
- the C content is less than 0.18%, the steel sheet does not have a predetermined strength.
- the amount of C exceeds 0.23%, the strength of the steel sheet is too high or the workability deteriorates.
- the lower limit of the C amount may be limited to 0.19% or 0.20%, and the upper limit of the C amount may be limited to 0.22%.
- Si acts as a deoxidizing material and a strengthening element, and its effect is recognized with addition of 0.1% or more.
- the Ac3 point Ac3 transformation point
- the upper limit of Si content is 0.5%.
- the upper limit of Si content may be limited to 0.40%, 0.32%, or 0.29%.
- Mn is an element effective for improving hardenability and improving strength, and also has an effect of lowering the Ac3 point. Therefore, at least 1.0% or more of Mn is added. However, if the amount of Mn exceeds 2.0%, segregation is promoted and toughness and weldability may be impaired. Therefore, 2.0% is made the upper limit of Mn addition. In order to secure the strength stably, even if the lower limit of the Mn amount is limited to 1.30%, 1.40% or 1.50%, and the upper limit of the Mn amount is limited to 1.89% or 1.79% Good.
- the P content is an inevitable impurity and a harmful element that lowers the bending workability. Therefore, the P content is suppressed to 0.020% or less. In order to improve the bending workability, the P content may be limited to 0.010% or less, 0.008% or less, or 0.005% or less.
- the S is also an unavoidable impurity and a harmful element that deteriorates delayed fracture resistance and weldability. Therefore, the S content is suppressed to 0.010% or less. In order to improve delayed fracture resistance and weldability, the amount of S may be limited to 0.006% or less or 0.003% or less.
- Ni is an extremely important element in the present invention because it has effects of improving hardenability and toughness and lowering the Ac3 point. Therefore, Ni is added at least 0.5% or more. However, since Ni is an expensive element, the addition amount is set to 3.0% or less. In order to improve toughness, the lower limit of the Ni amount may be limited to 0.8%, 1.0%, or 1.2%. Moreover, in order to suppress an increase in price, the upper limit of the Ni amount may be limited to 2.0%, 1.8%, or 1.5%.
- Nb has the effect of generating fine carbides during rolling to widen the non-recrystallization temperature range to enhance the controlled rolling effect and to introduce appropriate strain into the rolled structure before quenching.
- the pinning effect has the effect of suppressing austenite coarsening during quenching heating. Therefore, Nb is an essential element for obtaining the predetermined prior austenite grain size in the present invention. Therefore, Nb is added at 0.003% or more.
- the addition amount of Ni is set to 0.10% or less.
- the lower limit of the Nb amount may be limited to 0.008% and 0.012%.
- the upper limit of the Nb amount may be limited to 0.05%, 0.03%, or 0.02%.
- Al is added in an amount of 0.05% or more for the purpose of fixing N in order to secure free B necessary for improving hardenability.
- excessive addition of Al may reduce toughness, so the upper limit of Al content is 0.15%. Since excessive addition of Al has a concern of deteriorating the cleanliness of the steel, the upper limit of the Al amount may be limited to 0.11% or 0.08%.
- B is an essential element effective for enhancing hardenability.
- the amount of B needs to be 0.0003% or more.
- the B amount is set to 0.0003% or more and 0.0030% or less.
- the lower limit of the B amount may be limited to 0.0005% or 0.0008%.
- the upper limit of B may be limited to 0.0021% or 0.0016%.
- the toughness is lowered and BN is formed to inhibit the effect of improving the hardenability of B. Therefore, the N content is suppressed to 0.006% or less.
- a steel containing the above elements and the balance being Fe and inevitable impurities is the basic composition of the steel of the present invention. Furthermore, in this invention, 1 or more types can be added among Cu, Cr, Mo, V other than the said component.
- Cu is an element that can improve strength without reducing toughness by solid solution strengthening. Therefore, 0.05% or more of Cu may be added. However, even if a large amount of Cu is added, the strength improvement effect is limited, and Cu is an expensive element. Therefore, the addition of Cu is 0.5% or less. In order to further reduce the cost, the amount of Cu may be limited to 0.32% or less or 0.25% or less.
- Cr improves the hardenability and is effective for improving the strength. Therefore, you may add 0.05% or more of Cr. However, excessive addition of Cr may reduce toughness. Therefore, the addition of Cr is 1.5% or less. In order to prevent toughness deterioration, the upper limit of the Cr content may be limited to 1.0%, 0.7%, or 0.4%.
- Mo improves hardenability and is effective for improving strength. Therefore, you may add 0.03% or more of Mo.
- the effect of precipitation strengthening cannot be expected under the production conditions of the present invention having a low tempering temperature, the effect of improving the strength is limited even if a large amount of Mo is added.
- Mo is also an expensive element. Therefore, the addition of Mo is 0.5% or less.
- the upper limit of the Mo amount may be limited to 0.31% or 0.24%.
- V also improves hardenability and is effective in improving strength. Therefore, you may add 0.01% or more of V.
- V since the effect of precipitation strengthening cannot be expected under the production conditions of the present invention having a low tempering temperature, the effect of improving the strength is limited even if a large amount of V is added.
- V is also an expensive element. Therefore, the addition of V is set to 0.10% or less. If necessary, the V amount may be limited to 0.07% or 0.04%.
- the component composition in order to ensure weldability as described above, is limited so that Pcm represented by the following formula (1) is 0.36% or less. In order to further improve the weldability, it may be 0.35% or less or 0.34% or less.
- the carbon equivalent Ceq represented by the following formula (2) may be 0.80 or less.
- Ceq [C] + [Si] / 24 + [Mn] / 6 + [Ni] / 40 + [Cr] / 5 + [Mo] / 4 + [V] / 14 (2)
- hot rolling is performed by heating a steel slab or slab having the above steel composition.
- the heating temperature is 1100 ° C. or higher so that Nb is sufficiently dissolved.
- appropriate particle size control is performed in the range of prior austenite particle size numbers 8-11. Therefore, it is necessary to perform appropriate controlled rolling at the time of hot rolling, introduce an appropriate working strain to the steel sheet before quenching, and set the quenching heating temperature within the range of Ac3 transformation point + 20 ° C. to 850 ° C. It is.
- rolling is performed such that the cumulative reduction ratio in the temperature range of 930 ° C. or less and 860 ° C.
- the rolling is finished at 860 ° C. or more, and the sheet thickness is 4 A thick steel plate of 5 mm to 25 mm.
- the purpose of this controlled rolling is to introduce an appropriate working strain into the steel sheet before reheating and quenching.
- the said temperature range of controlled rolling is a non-recrystallization temperature range of the steel of the present invention in which an appropriate amount of Nb is contained. If the cumulative rolling reduction in this non-recrystallization temperature region is less than 30%, the processing strain is insufficient. Therefore, the austenite at the time of reheating becomes coarse. Further, if the cumulative rolling reduction in the non-recrystallization temperature region exceeds 65% or the rolling end temperature is 860 ° C.
- the working strain becomes excessive.
- the austenite at the time of heating may become a mixed grain structure. Therefore, even if the quenching heating temperature is within the following appropriate range, a sized structure having a prior austenite grain size number of 8 to 11 may not be obtained.
- the steel sheet After hot rolling, the steel sheet is cooled, reheated to a temperature not lower than Ac3 transformation point + 20 ° C. and not higher than 850 ° C., and then subjected to quenching heat treatment for accelerated cooling to 200 ° C. or lower.
- the quenching heating temperature must naturally be higher than the Ac3 transformation point. However, if the heating temperature is just above the Ac3 transformation point, the structure becomes mixed and appropriate particle size control may not be possible. Polygonal (isotropic) sizing cannot be reliably obtained unless the quenching heating temperature is higher than the Ac3 transformation point + 20 ° C. Therefore, in order to set the quenching heating temperature to 850 ° C. or less, the Ac 3 transformation point of the steel material needs to be 830 ° C.
- the steel sheet In the quenching heat treatment cooling, the steel sheet is acceleratedly cooled to 200 ° C. or lower under the condition that the average cooling rate from 600 ° C. to 300 ° C. at the center of the plate thickness is 20 ° C./sec or higher.
- a martensitic structure having a structure fraction of 90% or more can be obtained in a steel sheet having a thickness of 4.5 mm or more and 25 mm or less. Since the cooling rate at the center of the plate thickness cannot be directly measured, it is calculated by heat transfer calculation from the plate thickness, surface temperature, and cooling conditions.
- the martensitic structure in the as-quenched state has a low yield ratio. Therefore, tempering heat treatment is performed in a temperature range of 200 ° C.
- the tempering heat treatment is performed at 200 ° C. or higher and 300 ° C. or lower.
- the time for the tempering heat treatment may be about 15 minutes or more.
- Steel pieces A to AE having the composition shown in Tables 1 and 2 were melted to obtain steel pieces. From these steel slabs, steel sheets having a thickness of 4.5 to 25 mm were produced according to the production conditions of Examples 1 to 15 of the present invention shown in Table 3 and Comparative Examples of 16 to 46 shown in Table 5. . These steel sheets were evaluated for yield strength, tensile strength, prior austenite grain number, martensite structure fraction, weld crackability, bending workability, delayed fracture resistance, and toughness. Table 4 shows the results of Examples 1 to 15 of the present invention, and Table 6 shows the results of Comparative Examples 16 to 46. Further, the Ac3 transformation point was measured.
- the yield strength and the tensile strength were measured by taking a No. 1A tensile test piece specified in JIS Z 2201 and performing a tensile test specified in JIS Z 2241.
- the yield strength passed 1300 MPa or more, and the tensile strength passed 1400-1650 MPa.
- the prior austenite particle size number was measured by the method of JIS G 0551 (2005), and it was considered acceptable when the tensile strength and the prior austenite particle size number satisfy the above (a) and (b).
- five fields of 20 ⁇ m ⁇ 30 ⁇ m range were observed with a transmission electron microscope using a sample collected from the vicinity of the center of the plate thickness with a transmission electron microscope.
- the area of the martensite structure in each field of view was measured, and the martensite structure fraction was calculated from the average value of each area.
- the martensite structure has a high dislocation density, and very little cementite is produced by tempering heat treatment at 300 ° C. or lower. Therefore, the martensite structure can be distinguished from the bainite structure.
- the y-type weld cracking test specified in JIS Z 3158 was used. The thicknesses of the steel plates used for evaluation were all 25 mm except for Examples 2, 4, 9, and 11, and CO 2 welding with a heat input of 15 kJ / cm was performed.
- JIS Z 2248 For the evaluation of bending workability, the method specified in JIS Z 2248, using a JIS No. 1 test piece (the length direction of the test piece is the direction perpendicular to the rolling direction of the steel plate) is 3 times the plate thickness. Bending was performed 180 degrees so as to obtain a bending radius (3 t). After the bending test, the case where no cracks or other defects occurred on the outside of the curved portion was regarded as acceptable. In order to evaluate delayed fracture resistance, “limit diffusible hydrogen amount Hc” and “diffusible hydrogen amount HE invading from the environment” of each steel sheet were measured. When Hc / HE exceeded 3, it was evaluated that the delayed fracture resistance was good. In order to evaluate toughness, JIS Z 2201 No.
- Examples 1 to 15 of the present invention shown in Tables 3 and 4 the yield strength, tensile strength, prior austenite grain number, martensite structure fraction, weld crackability, bending workability, delayed fracture resistance, toughness All target values are satisfied.
- Comparative Examples 16 to 33 in Tables 5 and 6 the chemical components indicated by the underline in the table depart from the range limited by the present invention. Therefore, in Comparative Examples 16 to 33, yield strength, tensile strength, prior austenite grain size number, martensite structure fraction, weld crackability, bending workability, delayed fracture resistance, despite being within the range of the production conditions of the present invention. One or more of characteristics and toughness does not meet the target value.
- Comparative Example 34 the steel component composition is within the range of the present invention, but the Pcm value deviates from the range of the present invention, so the weld crackability is unacceptable.
- Comparative Example 35 the steel component composition is within the range of the present invention, but the Ac3 point deviates from the range of the present invention, so the quenching heating temperature cannot be lowered. Therefore, refinement
- Comparative Examples 36-46 the steel chemical composition, Pcm values, also A c3 point are all be within the scope the present invention, does not satisfy the production conditions of the present invention.
- At least one of yield strength, tensile strength, prior austenite grain size number, martensite structure fraction, weld crackability, bending workability, delayed fracture resistance, and toughness does not meet the target value. That is, in Comparative Example 36, since the heating temperature is low and Nb does not dissolve, the austenite is not sufficiently refined. Therefore, Comparative Example 36 is unacceptable in bending workability and delayed fracture resistance. In Comparative Example 37, since the cumulative rolling reduction at 930 ° C. or lower and 860 ° C. or higher is low, the austenite is not sufficiently refined. Therefore, the comparative example 37 is unacceptable for delayed fracture resistance. In Comparative Example 38, since the quenching heating temperature is less than 800 ° C., austenite becomes too fine.
- Comparative Example 38 has a low yield strength and is unacceptable.
- Comparative Example 39 since the quenching heating temperature exceeds 850 ° C., the austenite is not sufficiently refined. Therefore, the delayed fracture resistance is unacceptable.
- Comparative Example 40 since the cooling rate from 600 ° C. to 300 ° C. is small, a martensite structure fraction of 90% or more cannot be obtained. Therefore, yield strength is low and it is unacceptable. Since the comparative example 41 is not tempered, the yield strength is low and it is not acceptable. Since the tempering temperature exceeds 300 degreeC, the comparative example 42 has low toughness and is disqualified.
- Comparative Example 43 Since the comparative example 43 has higher tempering temperature than the comparative example 42, intensity
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Abstract
Description
本願は、2008年9月17日に、日本に出願された特願2008-237264号に基づき優先権を主張し、その内容をここに援用する。
溶接割れは、予熱温度の影響が大きく、図1には、溶接割れと予熱温度との関係を示している。前述のように150℃の予熱温度においてルート割れが完全に0となるためには、Pcmが0.36%以下であることが必要である。125℃の予熱温度においてルート割れが完全に0となるためには、Pcmが0.34%以下であることが必要である。
(a):引張強度が1400MPa以上、1550MPa未満では、Nγ≧([TS]-1400)×0.004+8.0、かつNγ≦11.0
(b):引張強度が1550MPa以上、1650MPa以下では、Nγ≧([TS]-1550)×0.008+8.6、かつNγ≦11.0
ここで、[TS]は、引張強度(MPa)、Nγは、旧オーステナイト結晶粒度番号である。(a)、(b)を満たす範囲は、図5中の太線で囲まれた領域で示される。
焼戻し熱処理をしない場合、すなわち焼入れたままの状態では、マルテンサイト組織の降伏比は低い。そのため、引張強度は高い反面、降伏強度が低くなる。降伏強度を1300MPa以上とするためには、C量は、およそ0.24%以上が必要である。しかしながら、このC量では引張強度1650MPa以下を満たすことが難しい。
一方、450℃以上で焼戻し熱処理されたマルテンサイト組織では、降伏比は増加するが、引張強度が大きく低下する。1400MPa以上の引張強度を確保するには、C量をおよそ0.35%以上とする必要がある。しかしながら、このC量では、溶接性を確保するためにPcmを0.36%以下とすることは困難である。
マルテンサイト組織鋼を200℃以上、300℃以下の低温で焼戻し熱処理することにより、引張強度をあまり低下させないで降伏比を高めることができる。この場合には、上記の降伏強度1300MPa以上、かつ引張強度1400MPa以上1650MPa以下の条件を満たすことが可能となる。
また、マルテンサイト組織鋼を300℃超、450℃未満程度の温度で焼戻した場合、いわゆる低温焼戻し脆化により靭性が低下する問題がある。しかしながら、焼戻し温度が200℃以上、300℃以下であれば、この焼戻し脆化は生じないので、靭性低下は問題とならない。
以上のことから、適切なC量と合金元素を含有するマルテンサイト組織鋼を200℃以上300℃以下の低温で焼き戻すことにより、靭性低下を伴うことなく降伏比を上昇させることができ、1300MPa以上の降伏強度と、1400MPa以上、1650MPa以下の引張強度を両立させ得るという知見を得るに至った。
(1)質量%で、C:0.18%以上、0.23%以下、Si:0.1%以上、0.5%以下、Mn:1.0%以上、2.0%以下、P:0.020%以下、S:0.010%以下、Ni:0.5%以上、3.0%以下、Nb:0.003%以上、0.10%以下、Al:0.05%以上、0.15%以下、B:0.0003%以上、0.0030%以下、N:0.006%以下を含み、残部がFeおよび不可避的不純物からなり、かつ[C]、[Si]、[Mn]、[Cu]、[Ni]、[Cr]、[Mo]、[V]、[B]を、それぞれ、C、Si、Mn、Cu、Ni、Cr、Mo、V、Bの濃度(質量%)とした場合に、Pcm=[C]+[Si]/30+[Mn]/20+[Cu]/20+[Ni]/60+[Cr]/20+[Mo]/15+[V]/10+5[B]により算出される溶接割れ感受性指標Pcmが0.36%以下であることを満たす成分組成を有し;Ac3変態点が830℃以下であり、マルテンサイト組織分率が90%以上であり、降伏強度が1300MPa以上であり、引張強度が1400MPa以上かつ1650MPa以下であり、さらに、引張強度と、試料片断面の1mm2当りの平均結晶粒数mを用いて、Nγ=-3+log2mにより算出される旧オーステナイト結晶粒度番号Nγとが、前記引張り強度を[TS](MPa)とした場合に、前記引張強度が1550MPa未満では、Nγ≧([TS]-1400)×0.004+8.0、かつNγ≦11.0を満たし、前記引張強度が1550MPa以上では、Nγ≧([TS]-1550)×0.008+8.6、かつNγ≦11.0を満たす;ことを特徴とする高強度厚鋼板。
まず、本発明の鋼成分の限定理由を述べる。
Cは、マルテンサイト組織の強度に大きく影響する重要な元素である。本発明において、C含有量は、マルテンサイト組織分率が90%以上であるときに、1300MPa以上の降伏強度と、1400MPa以上、1650MPa以下の引張強度とを得るために必要な量として決定される。C量の範囲は、0.18%以上0.23%以下である。C量が0.18%未満では、鋼板は、所定の強度を有さない。また、C量が0.23%超では、鋼板の強度が出過ぎるか、加工性が劣化する。強度を安定して確保するためには、C量の下限を0.19%または0.20%に、C量の上限を0.22%に制限してもよい。
Cuは、固溶強化により靭性を低下させないで強度を向上させ得る元素である。そのため、Cuを0.05%以上添加してもよい。しかしながら、Cuを多量に添加しても強度向上効果には限りがあり、Cuは、高価な元素でもある。そのため、Cuの添加は、0.5%以下とする。よりコストを抑えるために、Cu量を0.32%以下または0.25%以下に制限してもよい。
Pcm=[C]+[Si]/30+[Mn]/20+[Cu]/20+[Ni]/60+[Cr]/20+[Mo]/15+[V]/10+5[B]・・・(1)
ここで、[C]、[Si]、[Mn]、[Cu]、[Ni]、[Cr]、[Mo]、[V]、[B]は、それぞれ、C、Si、Mn、Cu、Ni、Cr、Mo、V、Bの質量%である。
Ceq=[C]+[Si]/24+[Mn]/6+[Ni]/40+[Cr]/5+[Mo]/4+[V]/14・・・(2)
まず、上記の鋼成分組成の鋼片または鋳片を加熱して熱間圧延を行う。加熱温度は、Nbが十分固溶するように、1100℃以上とする。
さらに、旧オーステナイト粒度番号8~11の範囲への適度な粒径制御を行う。そのため、熱間圧延時に適度な制御圧延を行って、焼入れ前の鋼板に適度な加工歪を導入し、焼入れ加熱温度をAc3変態点+20℃以上、かつ850℃以下の範囲とすることが必要である。
熱間圧延時の制御圧延では、930℃以下、860℃以上の温度範囲における累積圧下率が30%以上、65%以下となるように圧延し、860℃以上で圧延を終了して板厚4.5mm以上25mm以下の厚鋼板とする。この制御圧延の目的は、再加熱焼入れ前の鋼板に適度な加工歪を導入することにある。また、制御圧延の上記温度範囲は、Nbが適量含有された本発明鋼の未再結晶温度域である。この未再結晶温度域での累積圧下率が30%未満では、加工歪が不十分である。そのため、再加熱時のオーステナイトが粗大になる。また、未再結晶温度域での累積圧下率が65%超であったり、圧延終了温度が860℃以下であったりすると、加工歪が過剰になる。この場合には、加熱時のオーステナイトが混粒組織となることがある。そのため、焼入れ加熱温度が下記の適正範囲であっても、旧オーステナイト粒度番号8~11の整粒組織が得られないことがある。
焼入れたままの状態のマルテンサイト組織は、降伏比が低い。そのため、降伏強度を上昇させることを目的として、200℃以上、300℃以下の温度範囲で焼戻し熱処理を行う。焼戻し温度が200℃未満では、降伏強度上昇効果が得られない。逆に、焼戻し温度が300℃を越えると、焼戻し脆化のため靭性が低下する。そのため、焼戻し熱処理は、200℃以上、300℃以下とする。焼戻し熱処理の時間は、15分程度以上あればよい。
これらの鋼板について、降伏強度、引張強度、旧オーステナイト粒度番号、マルテンサイト組織分率、溶接割れ性、曲げ加工性、耐遅れ破壊特性、靭性を評価した。表4に1~15の本発明の実施例の結果を、表6に16~46の比較例の結果を示している。また、Ac3変態点を実測した。
旧オーステナイト粒度番号は、JIS G 0551(2005)の方法で測定し、引張強度と旧オーステナイト粒度番号とが、前記(a)、(b)を満たす場合に合格とした。
マルテンサイト組織分率の評価のために、板厚中心部付近から採取したサンプルを用いて、透過型電子顕微鏡により、倍率5000倍で20μm×30μmの範囲を5視野観察した。それぞれの視野におけるマルテンサイト組織の面積を測定し、それぞれの面積の平均値からマルテンサイト組織分率を算出した。この際、マルテンサイト組織は、転位密度が高く、300℃以下の焼戻し熱処理ではセメンタイトはごくわずかしか生成しない。そのため、マルテンサイト組織をベイナイト組織などと区別できる。
溶接割れ性の評価のために、JIS Z 3158に規定のy型溶接割れ試験で評価を行った。評価に供する鋼板の板厚は、実施例2、4、9、11を除きすべて25mmであり、入熱15kJ/cmのCO2溶接を行った。試験の結果、予熱温度150℃でルート割れ率が0であれば合格と評価した。また、板厚が25mm未満の実施例2、4、9、11の鋼板については、溶接性は同一成分の実施例1、3、8、12と同じであると考えられるため、y型溶接割れ試験を省略した。
耐遅れ破壊特性の評価のために、それぞれの鋼板の「限界拡散性水素量Hc」および「環境から侵入する拡散性水素量HE」を測定した。Hc/HEが3を超える場合に、耐遅れ破壊特性が良好であると評価した。
靱性の評価のために、JIS Z 2201 4号シャルピー試験片を板厚中心部から圧延方向に対して直角に採取し、3本の試験片に対し-20℃においてシャルピー衝撃試験を行った。それぞれの試験片の吸収エネルギーの平均値を計算し、その平均値が27J以上であることを目標とした。なお、板厚が9mmの鋼板(実施例9)については5mmサブサイズのシャルピー試験片、板厚が4.5mmの鋼板(実施例2)については3mmサブサイズのシャルピー試験片を用いた。サブサイズのシャルピー試験片に対しては、4号シャルピー試験片の板幅であると仮定した場合(すなわち、板幅10mm)の吸収エネルギー値が27J以上であることを目標値とした。
尚、Ac3変態点は、富士電波工機製Formastor-FIIを用いて、2.5℃/分での昇温速度条件で熱膨張測定により測定した。
Claims (4)
- 質量%で、
C:0.18%以上、0.23%以下、
Si:0.1%以上、0.5%以下、
Mn:1.0%以上、2.0%以下、
P:0.020%以下、
S:0.010%以下、
Ni:0.5%以上、3.0%以下、
Nb:0.003%以上、0.10%以下、
Al:0.05%以上、0.15%以下、
B:0.0003%以上、0.0030%以下、
N:0.006%以下
を含み、残部がFeおよび不可避的不純物からなり、かつ[C]、[Si]、[Mn]、[Cu]、[Ni]、[Cr]、[Mo]、[V]、[B]を、それぞれ、C、Si、Mn、Cu、Ni、Cr、Mo、V、Bの濃度(質量%)とした場合に、Pcm=[C]+[Si]/30+[Mn]/20+[Cu]/20+[Ni]/60+[Cr]/20+[Mo]/15+[V]/10+5[B]により算出される溶接割れ感受性指標Pcmが0.36%以下であることを満たす成分組成を有し;
Ac3変態点が830℃以下であり、マルテンサイト組織分率が90%以上であり、降伏強度が1300MPa以上であり、引張強度が1400MPa以上かつ1650MPa以下であり、さらに、引張強度と、試料片断面の1mm2当りの平均結晶粒数mを用いて、Nγ=-3+log2mにより算出される旧オーステナイト結晶粒度番号Nγとが、前記引張り強度を[TS](MPa)とした場合に、前記引張強度が1550MPa未満では、Nγ≧([TS]-1400)×0.004+8.0、かつNγ≦11.0を満たし、前記引張強度が1550MPa以上では、Nγ≧([TS]-1550)×0.008+8.6、かつNγ≦11.0を満たす;
ことを特徴とする高強度厚鋼板。 - 質量%で、さらに、
Cu:0.05%以上、0.5%以下、
Cr:0.05%以上、1.5%以下、
Mo:0.03%以上、0.5%以下、
V:0.01%以上、0.10%以下
のうちの1種以上を含むことを特徴とする、請求項1に記載の高強度厚鋼板。 - 板厚が4.5mm以上25mm以下であることを特徴とする、請求項1または請求項2に記載の高強度厚鋼板。
- 請求項1または請求項2に記載の成分組成を有する鋼片または鋳片を1100℃以上に加熱し;
板厚が4.5mm以上、25mm以下の鋼板となるように、930℃以下、860℃以上の温度範囲での累積圧下率が30%以上、65%以下であり、860℃以上で圧延を終了する熱間圧延を行い;
冷却後、前記鋼板をAc3変態点+20℃以上、かつ850℃以下の温度に再加熱し;
その後、600℃から300℃までの前記鋼板の板厚中心部における平均冷却速度が20℃/sec以上となる冷却条件で200℃以下まで加速冷却を行い;
さらにその後、200℃以上、300℃以下の温度範囲で焼戻し熱処理を行う;
ことを特徴とする高強度厚鋼板の製造方法。
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EP (1) | EP2267177B1 (ja) |
JP (1) | JP4538094B2 (ja) |
KR (1) | KR101011072B1 (ja) |
CN (1) | CN101835918B (ja) |
AU (1) | AU2009294126B2 (ja) |
BR (2) | BRPI0905362B1 (ja) |
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- 2009-09-14 JP JP2010503308A patent/JP4538094B2/ja active Active
- 2009-09-14 TW TW098130926A patent/TWI340170B/zh not_active IP Right Cessation
- 2009-09-14 WO PCT/JP2009/004583 patent/WO2010032428A1/ja active Application Filing
- 2009-09-14 CN CN200980100797XA patent/CN101835918B/zh not_active Expired - Fee Related
- 2009-09-14 BR BR122017002730-1A patent/BR122017002730B1/pt not_active IP Right Cessation
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Cited By (4)
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JP2014029004A (ja) * | 2011-09-30 | 2014-02-13 | Jfe Steel Corp | 溶接性および耐遅れ破壊特性に優れた高張力鋼板の製造方法 |
JP2014029003A (ja) * | 2011-09-30 | 2014-02-13 | Jfe Steel Corp | 耐遅れ破壊特性に優れた高張力鋼板の製造方法 |
JP2021172838A (ja) * | 2020-04-22 | 2021-11-01 | Jfeスチール株式会社 | 高強度鋼板およびその製造方法 |
JP7287334B2 (ja) | 2020-04-22 | 2023-06-06 | Jfeスチール株式会社 | 高強度鋼板およびその製造方法 |
Also Published As
Publication number | Publication date |
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AU2009294126A1 (en) | 2010-03-25 |
KR101011072B1 (ko) | 2011-01-25 |
US8216400B2 (en) | 2012-07-10 |
BRPI0905362A2 (pt) | 2015-06-30 |
BR122017002730B1 (pt) | 2018-02-06 |
AU2009294126B2 (en) | 2011-03-10 |
US20100230016A1 (en) | 2010-09-16 |
JPWO2010032428A1 (ja) | 2012-02-02 |
CN101835918A (zh) | 2010-09-15 |
EP2267177B1 (en) | 2013-01-23 |
KR20100060020A (ko) | 2010-06-04 |
EP2267177A4 (en) | 2011-06-22 |
JP4538094B2 (ja) | 2010-09-08 |
CN101835918B (zh) | 2011-12-21 |
EP2267177A1 (en) | 2010-12-29 |
BRPI0905362B1 (pt) | 2017-07-04 |
TWI340170B (en) | 2011-04-11 |
TW201016863A (en) | 2010-05-01 |
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