WO2017105109A1 - Matériau en acier à haute résistance ayant d'excellentes propriétés au choc par vieillissement par contrainte à basse température et son procédé de fabrication - Google Patents

Matériau en acier à haute résistance ayant d'excellentes propriétés au choc par vieillissement par contrainte à basse température et son procédé de fabrication Download PDF

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WO2017105109A1
WO2017105109A1 PCT/KR2016/014734 KR2016014734W WO2017105109A1 WO 2017105109 A1 WO2017105109 A1 WO 2017105109A1 KR 2016014734 W KR2016014734 W KR 2016014734W WO 2017105109 A1 WO2017105109 A1 WO 2017105109A1
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steel
less
strength
strain aging
aging impact
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Korean (ko)
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엄경근
김우겸
이홍주
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Posco Holdings Inc
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Posco Co Ltd
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Priority to EP16876051.0A priority Critical patent/EP3392367B1/fr
Priority to JP2018528629A priority patent/JP6616002B2/ja
Priority to CN201680073003.5A priority patent/CN108368593B/zh
Priority to US16/061,160 priority patent/US20180363111A1/en
Publication of WO2017105109A1 publication Critical patent/WO2017105109A1/fr
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Priority to US18/537,245 priority patent/US20240110267A1/en
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
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    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties of ferrous metals or ferrous alloys 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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    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties of ferrous metals or ferrous alloys 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 of ferrous metals or ferrous alloys 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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    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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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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    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • 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
    • 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
    • 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
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • 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
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • 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
    • C21D2211/002—Bainite
    • 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
    • C21D2211/005—Ferrite
    • 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
    • C21D2211/009—Pearlite

Definitions

  • the present invention relates to steel materials used as materials for pressure vessels, offshore structures, and more particularly, to high-strength steels having excellent low-temperature strain aging impact characteristics and a method of manufacturing the same.
  • the steel used for this purpose is required to have excellent low temperature toughness in order to secure high strength and facility stability in order to reduce weight.
  • Mechanisms for reducing toughness by strain aging are as follows.
  • the toughness of the steel measured by the Charpy impact test is explained by the correlation between the yield strength and the fracture strength at the test temperature. If the yield strength of the steel at the test temperature is greater than the fracture strength, the steel will be brittle without fracture. While the impact energy value is inferior, when the yield strength is less than the fracture strength, the steel is deformed to be ductile and hardened and absorbs the impact energy as it is hardened, but when the yield strength reaches the fracture strength, it is changed to brittle fracture. In other words, as the difference between the yield strength and the fracture strength increases, the amount of deformation of the steel to ductility increases, so that the impact energy absorbed increases. Therefore, when cold deformation of steel for the production of steel pipes or other complex structures, the yield strength of the steel increases as the deformation continues, resulting in a decrease in impact toughness due to a small difference between the fracture strength.
  • Non-Patent Document 1 Effect of Ti on Deformation Aging of Low Carbon Steel Wires (Ochiaikuo, Obahiroshi, Iron and Steel 75th Year (1989) No. 4, P. 642 ⁇ )
  • Non-Patent Document 2 The effect of processing variables on the mechanical properties and strain ageing of high-strength low-alloy V and VN steels (VK Heikkinen and JD Boyd, CANADIAN METALLURGICAL QUARTERLY Volume 15 Number 3 (1976), P. 219 To)
  • One aspect of the present invention can minimize the increase in strength due to cold deformation to provide a steel material and a method of manufacturing the same can be suitably applied as a material for pressure vessels, offshore structures, etc. It is.
  • carbon (C) 0.04 ⁇ 0.14%
  • silicon (Si) 0.05 ⁇ 0.60%
  • manganese (Mn) 0.6 ⁇ 1.8%
  • soluble aluminum (Sol.Al) 0.005 ⁇ 0.06%
  • niobium (Nb) 0.005 to 0.05%
  • vanadium (V) 0.01% or less (excluding 0%)
  • titanium (Ti) 0.001 to 0.015%
  • Chromium (Cr) 0.01-0.2%
  • Molybdenum (Mo) 0.001-0.3%
  • Phosphorus (P) 0.02% or less (excluding 0%)
  • sulfur (S) 0.003% or less (excluding 0%)
  • residual Fe and other unavoidable impurities
  • High-strength steel material containing fine mixed ferrite, pearlite, bainite and MA (Martensite-Austenitic composite phase) as a microstructure, and having excellent low-temperature strain aging impact properties with a fraction of 3.5% or less (excluding 0%) of the MA phase.
  • the step of reheating the steel slab that satisfies the above-described component composition in the temperature range of 1080 ⁇ 1250 °C Manufacturing the hot-rolled steel sheet by rolling the reheated slab to a rolling end temperature of 780 ° C. or more; Cooling the hot rolled steel sheet by air cooling or water cooling; And it provides a method of manufacturing a high strength steel excellent in low temperature strain aging impact characteristics comprising the step of normalizing heat treatment in the temperature range of 850 ⁇ 960 °C after the cooling.
  • 1 is a graph showing the lower yield strength and tensile strength in the tensile curve of the steel according to an aspect of the present invention.
  • the inventors have continued to increase the cold deformation amount of steels used as materials for pressure vessels, offshore structures, etc., while deeply developing steels having high strength and high toughness while preventing toughness of steels from deformation aging.
  • the steel material having a microstructure advantageous for securing the above-described physical properties can be provided from the optimization of the steel component composition and manufacturing conditions, and thus, the present invention has been completed.
  • the steel material of the present invention is to minimize the MA phase (martensite-austenite composite phase) in the range of securing the toughness of the steel by optimizing the content of the elements affecting the formation of the MA phase in the steel composition toughness by strain aging The fall can be effectively prevented.
  • MA phase martensite-austenite composite phase
  • the high-strength steel having excellent low-temperature strain aging impact characteristics in weight%, carbon (C): 0.04 ⁇ 0.14%, silicon (Si): 0.05 ⁇ 0.60%, manganese (Mn): 0.6 ⁇ 1.8 %, Soluble Aluminum (Sol.Al): 0.005-0.06%, Niobium (Nb): 0.005-0.05%, Vanadium (V): 0.01% or less (excluding 0%), Titanium (Ti): 0.001-0.015%, Copper (Cu): 0.01-0.4%, Nickel (Ni): 0.01-0.6%, Chromium (Cr): 0.01-0.2%, Molybdenum (Mo): 0.001-0.3%, Calcium (Ca): 0.0002-0.0040%, Nitrogen (N): 0.001 to 0.006%, phosphorus (P): 0.02% or less (excluding 0%), sulfur (S): 0.003% or less (excluding 0%)
  • the content of each component means weight%.
  • Carbon (C) is an advantageous element for securing the strength of steel, and is a major element for securing tensile strength by being present as carbon and nitride in combination with pearlite, niobium (Nb), nitrogen (N), and the like. If the C content is less than 0.04%, the tensile strength on the matrix may be lowered, which is undesirable. On the other hand, if the content exceeds 0.14%, the pearlite may be excessively formed to deteriorate the strain aging impact characteristics at low temperatures. There is a risk of making.
  • the content of C in the present invention is preferably limited to 0.04 ⁇ 0.14%.
  • Silicon (Si) is an element added for the purpose of strengthening solid solution with deoxidation and desulfurization of steel, and is preferably added at 0.05% or more to secure yield strength and tensile strength. However, if the content exceeds 0.60%, the weldability and low temperature impact characteristics are deteriorated, and the steel surface is easily oxidized, so that an oxide film may be severely formed, which is not preferable.
  • the content of Si in the present invention is preferably limited to 0.05 ⁇ 0.60%.
  • Manganese (Mn) is preferably added at least 0.6% because the strength increase effect by solid solution strengthening.
  • MnS Manganese
  • the MnS inclusions generated in the center portion are stretched by rolling, and as a result, there is a problem of significantly inhibiting low-temperature toughness and resistance to lamella tear, so it is preferable to control the Mn content to 1.8% or less.
  • the content of Mn in the present invention is preferably limited to 0.6 ⁇ 1.8%.
  • Soluble aluminum (Sol.Al) is used as a strong deoxidizer in the steelmaking process together with Si, and it is preferable to add at least 0.005% at the time of single or complex deoxidation.
  • the content exceeds 0.06%, the above-mentioned effect is saturated, and the fraction of Al 2 O 3 in the oxidative inclusions produced by the deoxidation of the deoxidation increases more than necessary and its size is coarse to remove during refining. It is not easy, which is undesirable since it will eventually greatly reduce the low temperature toughness.
  • the content of Sol.Al in the present invention is preferably limited to 0.005 ⁇ 0.06%.
  • Niobium (Nb) is dissolved in austenite during slab reheating to increase the hardenability of austenite, and precipitates as fine carbon nitride (Nb, Ti) (C, N) during hot rolling to suppress recrystallization during rolling or cooling.
  • the effect of finely forming the final microstructure is great.
  • the amount of Nb added increases the strength by promoting bainite or MA formation, but when the content exceeds 0.05%, excessive MA formation and coarse precipitates are formed in the center of the thickness direction. Since it becomes easy and there exists a problem to inhibit the low-temperature toughness of the center part of steel materials, it is unpreferable.
  • the content of Nb in the present invention is preferably limited to 0.005 ⁇ 0.05%, more preferably 0.02% or more, even more advantageously limited to 0.022% or more.
  • V 0.01% or less (except 0%)
  • V Vanadium
  • V is almost completely reused upon slab reheating, and thus hardly increases the strength due to precipitation or solid solution in the state after rolling and normalizing heat treatment.
  • V has a problem of causing a cost increase when a large amount of V is added as an expensive element, it is preferable to add V to 0.01% or less.
  • Titanium (Ti) exists as a hexagonal precipitate mainly in the form of TiN at high temperature, or forms carbon / nitride (Nb, Ti) (C, N) precipitates such as Nb to suppress grain growth of the weld heat affected zone. have.
  • Nb, Ti carbon / nitride
  • C, N carbon / nitride precipitates
  • the content of Ti in the present invention is preferably limited to 0.001 ⁇ 0.015%.
  • Copper (Cu) is an element that can greatly improve the strength by solid solution and precipitation, and does not significantly deteriorate the strain aging impact characteristics, but if excessively added, it causes cracks on the steel surface and is an expensive element. In consideration of this, it is preferable to limit the content to 0.01 ⁇ 0.4%.
  • Nickel (Ni) has little effect of increasing strength, but is effective in improving the strain aging impact characteristics at low temperatures, and particularly, in the case of adding Cu, suppresses surface cracks due to selective oxidation generated during reheating of the slab. To this end, it is preferable to add Ni to 0.01% or more, but it is preferable to limit the content to 0.6% or less in consideration of economical efficiency as an expensive element.
  • Chromium (Cr) has a small effect of increasing yield strength and tensile strength due to solid solution, but has an effect of preventing a drop in strength by slowing down the decomposition rate of cementite during tempering or heat treatment after welding. To this end, it is preferable to add Cr in an amount of 0.01% or more, but if the content exceeds 0.2%, not only the manufacturing cost increases but also the problem of inhibiting low temperature toughness of the weld heat affected zone is not preferable.
  • Molybdenum (Mo) has the effect of delaying transformation in the cooling process after heat treatment and consequently increasing the strength, and also effective in preventing the strength drop during heat treatment after tempering or welding like Cr, and grain boundary segregation of impurities such as P It is effective in preventing the fall of toughness by.
  • the content of Ca in the present invention is preferably limited to 0.0002 ⁇ 0.0040%.
  • N Nitrogen
  • Nb, Ti, Al and the like Nitrogen (N) combines with added Nb, Ti, Al and the like to form a precipitate to refine the crystal grains of the steel to improve the strength and toughness of the base metal, but if the content is excessive, N remaining atoms after forming the precipitate It is known as the most representative element that exists in the state and causes aging after cold deformation, thereby reducing low-temperature toughness.
  • N Nitrogen
  • the content of N it is preferable to limit the content of N to 0.001 ⁇ 0.006%.
  • Phosphorus (P) has the effect of increasing the strength when added, but in the heat-treated steel of the present invention, it is preferable to manage as low as possible as it is an element that significantly deteriorates low-temperature toughness due to grain boundary segregation as compared to the strength increase effect. However, since excessive cost is required to remove excessively P in the steelmaking process, it is preferable to limit it to a range that does not affect physical properties, that is, 0.02% or less.
  • S Sulfur
  • MnS inclusions in the thickness direction of the steel sheet by combining with Mn. Therefore, in order to secure the strain aging impact characteristics at low temperature, it is preferable to manage the content of S as low as possible, but it takes considerable cost to remove such S excessively, so that it does not affect the physical properties, that is, 0.003 Preferably limited to% or less.
  • the remaining component of the present invention is iron (Fe).
  • iron Fe
  • impurities which are not intended from raw materials or the surrounding environment may be inevitably mixed, and thus cannot be excluded. Since these impurities are known to those skilled in the art of ordinary steel manufacturing, not all of them are specifically mentioned herein.
  • the high-strength steel of the present invention that satisfies the above-described alloy component composition preferably includes a mixed structure of ferrite, pearlite, bainite, and MA (martensite-austenite composite phase) as a microstructure.
  • ferrite is the most important structure that enables the soft deformation of the steel, and it is preferable to include such ferrite as a main phase and to finely control the average size to 15 ⁇ m or less.
  • ferrite grains fine, it is possible to increase the grain boundary to suppress the propagation of cracks, improve the basic toughness of the steel, and minimize the increase in strength due to the effect of lowering the work hardening rate during cold deformation.
  • the strain aging impact characteristics can also be improved at the same time.
  • Hard phases including the pearlite, bainite, MA, etc., except for the ferrite, are advantageous for increasing the tensile strength of the steel to secure high strength, but due to the high hardness, the hardening phase becomes a starting point of failure or a propagation path and thus has a deformation aging impact characteristic. There is a problem to inhibit. Therefore, it is desirable to control the fraction, and it is preferable to limit the sum of the fractions of the hard phases to 18% or less (excluding 0%).
  • the MA phase since the MA phase has the highest strength and transforms into brittle martensite by deformation, it is the factor that most significantly inhibits low-temperature toughness. Therefore, it is preferable to limit the fraction of MA phase to 3.5% or less (except 0%), and more preferably to 1.0 to 3.5%.
  • the high-strength steel of the present invention having the microstructure as described above includes carbon and nitride produced by Nb, Ti, Al, etc. of the added elements, the carbon nitride is grain growth during the rolling, cooling, heat treatment process Suppresses and plays an important role to make finer.
  • the reheating temperature is preferably controlled to 1080 ⁇ 1250 °C, if the reheating temperature is less than 1080 °C it becomes difficult to re-use the carbide generated in the slab during the performance. Therefore, it is preferable to carry out above the temperature at which Nb added in the present invention can be re-used at least 50%.
  • the temperature exceeds 1250 °C, the austenite grain size is too coarse, there is a problem that the mechanical properties such as strength and toughness of the final steel is greatly reduced.
  • the reheating temperature in the present invention is preferably limited to 1080 ⁇ 1250 °C.
  • finishing rolling process is controlled rolling, and it is preferable to control the rolling end temperature to 780 ° C or higher.
  • the end temperature of rolling is about 820 ⁇ 1000 °C, but when it is lowered below 780 °C, the hardenability is lowered in the region where Mn is not segregated during rolling, so that ferrite is formed during rolling. As is generated, C and solute are segregated into the residual austenite region and concentrated. Accordingly, the region where C or the like is concentrated during cooling after rolling is transformed into bainite, martensite, or MA phase to produce a strong layered structure composed of ferrite and hardened structure.
  • the hardened structure of the layer where C and the like are concentrated has not only high hardness but also a large increase in the fraction of the MA phase. As described above, since the low-temperature toughness is reduced by increasing the hardened structure and the arrangement in the layered structure, it is preferable to control the rolling end temperature to 780 ° C or higher.
  • the hot rolled steel sheet obtained by control rolling may be cooled by air cooling or water cooling, and then normalized heat treatment at a predetermined temperature range may produce a steel material having target properties.
  • the normalizing heat treatment is preferably maintained in a temperature range of 850 ⁇ 960 °C for a predetermined time and then cooled in the air. If the normalizing heat treatment temperature is less than 850 ° C., re-use of cementite and MA in pearlite and bainite is difficult to re-use, so that the amount of dissolved C decreases, making it difficult to secure strength and finally remaining hardened phase remains coarse. Aging impact toughness is also greatly worsened. On the other hand, when the temperature exceeds 960 °C grain growth occurs there is a problem that inhibits the strain aging impact characteristics.
  • the high-strength steel obtained as described above is not only excellent in strength and toughness, but also can effectively prevent a decrease in toughness due to strain aging during cold deformation.
  • the yield ratio after heat treatment (YS (lower yield strength) / TS (tensile strength)) can be secured to 0.65 ⁇ 0.80.
  • the steel slab having the composition of the following Table 1 was subjected to reheating, hot rolling and normalizing heat treatment under the conditions shown in Table 2 below to produce a hot rolled steel sheet having a final thickness of 6 mm or more.
  • the microstructure fraction, size and carbon and nitride fraction and size were measured.
  • the Charpy impact transition temperature was measured by aging at 250 ° C. for 1 hour after cold deformation 5% tensile strength, which can represent the strength (tensile strength and lower yield strength) and deformation aging impact characteristics of each hot rolled steel sheet. Shown in
  • each hot-rolled steel sheet is polished by mirror surface of steel sheet and then etched with Nital or Lepera according to the purpose, and a certain area of the specimen is 100 ⁇ 500 times magnified by optical or scanning electron microscope. After measuring the fraction of each phase from the measured image using an image analyzer (image analyzer). In order to obtain statistically significant values, the same specimens were repositioned and repeatedly measured, and their average values were obtained.
  • image analyzer image analyzer
  • the fraction of fine carbon and nitride with an average size of 300 mm or less was measured by the extraction residue method.
  • Tensile characteristic values were measured from the nominal strain-nominal stress curves obtained by the normal tensile test, respectively, and the lower yield strength, tensile strength, and yield ratio (lower yield strength / tensile strength) were measured. , 5% and 8% were added in advance, and the stretched specimens were aged at 250 ° C. for 1 hour and then measured by Charpy V-notch impact test.
  • the said hardening phase fraction (%) is shown including the carbon-nitride fraction (%).
  • the hot-rolled steel sheets of Inventive Examples 1 to 3 satisfying both the composition of the composition and the manufacturing conditions of the present invention are not only high strength, but also have excellent low-temperature toughness even after cold deformation, thereby increasing the size and complexity. Suitable for pressure vessels, offshore structures, etc.
  • Comparative Examples 3 to 7 is a case in which the manufacturing conditions satisfy the present invention, but the steel composition does not satisfy the present invention, it can be confirmed that the strength is low or the low-temperature toughness deteriorated.
  • Comparative Example 3 is a case where the content of C is not sufficient, ferrite grains are coarsened during rolling and heat treatment, and sufficient strength cannot be secured.
  • Comparative Example 4 is a case where the content of C is excessive, the hardening phase fraction is more than 18%, the yield ratio is lowered as the fraction of the MA phase is also significantly increased, and eventually the impact transition temperature after 5% cold deformation was high.
  • Comparative Example 5 is a case in which the content of Ti is excessive, in which excessively added Ti is formed as a coarse TiN precipitate compared to the added N, which acts as a starting point of the crack during impact after 5% cold deformation, thereby increasing the impact transition temperature. The result was obtained.
  • Comparative Example 7 is a case in which the Cu content is excessive, such Cu increases the solubility of austenite C during cooling after normalizing heat treatment, thereby increasing the fraction of MA phase after the final transformation, thereby lowering the yield ratio and 5% cold The result was to increase the impact transition temperature after deformation.

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Abstract

La présente invention concerne un matériau en acier pour des récipients sous pression, des installations au large des côtes et autres et, plus précisément, un matériau en acier à haute résistance, ayant d'excellentes propriétés au choc par vieillissement par contrainte à basse température, et un procédé de fabrication de celui-ci, le matériau en acier à haute résistance comprenant 0,04 à 0,14 % en poids de carbone (C), 0,05 à 0,60 % en poids de silicium (Si), 0,6 à 1,8 % en poids de manganèse (Mn), 0,005 à 0,06 % en poids d'aluminium soluble (Al sol.), 0,005 à 0,05 % en poids de niobium (Nb), 0,01 % en poids ou moins (0 % en poids n'étant pas inclus) de vanadium (V), 0,001 à 0,015 % en poids de titane (Ti), 0,01 à 0,4 % en poids de cuivre (Cu), 0,01 à 0,6 % en poids de nickel (Ni), 0,01 à 0,2 % en poids de chrome (Cr), 0,001 à 0,3 % en poids de molybdène (Mo), 0,0002 à 0,0040 % en poids de calcium (Ca), 0,001 à 0,006 % en poids d'azote (N), 0,02 % en poids ou moins de phosphore (P) (0 % en poids n'étant pas inclus) et 0,003 % en poids ou moins de soufre (S) (0 % en poids n'étant pas inclus), le reste étant du Fe et les impuretés inévitables, et comportant une structure mixte de ferrite, de perlite, de bainite et d'un composite de martensite-austénite (MA) en tant que microstructure, la fraction du composite de MA étant inférieure ou égale à 3,5 % (0 % n'étant pas inclus).
PCT/KR2016/014734 2015-12-15 2016-12-15 Matériau en acier à haute résistance ayant d'excellentes propriétés au choc par vieillissement par contrainte à basse température et son procédé de fabrication Ceased WO2017105109A1 (fr)

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EP16876051.0A EP3392367B1 (fr) 2015-12-15 2016-12-15 Matériau en acier à haute résistance ayant d'excellentes propriétés au choc par vieillissement par contrainte à basse température et son procédé de fabrication
JP2018528629A JP6616002B2 (ja) 2015-12-15 2016-12-15 低温歪み時効衝撃特性に優れた高強度鋼材及びその製造方法
CN201680073003.5A CN108368593B (zh) 2015-12-15 2016-12-15 具有优异的低温应变时效冲击特性的高强度钢材及其制造方法
US16/061,160 US20180363111A1 (en) 2015-12-15 2016-12-15 High-strength steel material having excellent low-temperature strain aging impact properties and method for manufacturing same
US18/537,245 US20240110267A1 (en) 2015-12-15 2023-12-12 High-strength steel material having excellent low-temperature strain again impact properties and method for manufacturing same

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WO2019037749A1 (fr) * 2017-08-23 2019-02-28 宝山钢铁股份有限公司 Acier pour utilisation dans une cuve sous pression à basse température et son procédé de fabrication
EP3719162A4 (fr) * 2017-12-01 2020-11-18 Posco Matériau en acier à haute résistance ayant une excellente résistance à la fissuration induite par l'hydrogène et une ténacité à l'impact à basse température et son procédé de fabrication
US11136653B2 (en) 2015-12-15 2021-10-05 Posco High-strength steel material having excellent low-temperature strain aging impact properties and welding heat-affected zone impact properties and method for manufacturing same
US20210395867A1 (en) * 2018-11-30 2021-12-23 Posco Steel plate for pressure vessel having excellent hydrogen induced cracking resistance and method of manufacturing same
US20220282352A1 (en) * 2019-08-23 2022-09-08 Posco Thin steel plate having excellent low-temperature toughness and ctod properties, and method for manufacturing same

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WO2021256590A1 (fr) * 2020-06-19 2021-12-23 현대제철 주식회사 Barre d'armature et procédé de fabrication correspondant
KR20230089767A (ko) * 2021-12-14 2023-06-21 주식회사 포스코 고강도 및 충격인성이 우수한 강재 및 그 제조방법
KR20230090416A (ko) * 2021-12-14 2023-06-22 주식회사 포스코 수소유기균열 저항성 및 저온 충격인성이 우수한 강재 및 그 제조방법

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US11136653B2 (en) 2015-12-15 2021-10-05 Posco High-strength steel material having excellent low-temperature strain aging impact properties and welding heat-affected zone impact properties and method for manufacturing same
WO2019037749A1 (fr) * 2017-08-23 2019-02-28 宝山钢铁股份有限公司 Acier pour utilisation dans une cuve sous pression à basse température et son procédé de fabrication
EP3719162A4 (fr) * 2017-12-01 2020-11-18 Posco Matériau en acier à haute résistance ayant une excellente résistance à la fissuration induite par l'hydrogène et une ténacité à l'impact à basse température et son procédé de fabrication
JP2021504582A (ja) * 2017-12-01 2021-02-15 ポスコＰｏｓｃｏ 耐水素誘起割れ性及び低温衝撃靭性に優れた高強度鋼材及びその製造方法
JP7197582B2 (ja) 2017-12-01 2022-12-27 ポスコ 耐水素誘起割れ性及び低温衝撃靭性に優れた高強度鋼材及びその製造方法
US20210395867A1 (en) * 2018-11-30 2021-12-23 Posco Steel plate for pressure vessel having excellent hydrogen induced cracking resistance and method of manufacturing same
US12227826B2 (en) * 2018-11-30 2025-02-18 Posco Co., Ltd Steel plate for pressure vessel having excellent hydrogen induced cracking resistance and method of manufacturing same
US20220282352A1 (en) * 2019-08-23 2022-09-08 Posco Thin steel plate having excellent low-temperature toughness and ctod properties, and method for manufacturing same
US12559813B2 (en) * 2019-08-23 2026-02-24 Posco Thin steel plate having excellent low-temperature toughness and CTOD properties, and method for manufacturing same

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JP6616002B2 (ja) 2019-12-04
CN108368593A (zh) 2018-08-03
EP3392367B1 (fr) 2021-10-27
EP3392367A1 (fr) 2018-10-24
US20240110267A1 (en) 2024-04-04
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CN108368593B (zh) 2020-10-02
EP3392367A4 (fr) 2019-02-27
KR20170071639A (ko) 2017-06-26

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