US20190382865A1 - Heavy-wall steel plate having 450mpa-grade tensile strength and excellent resistance to hydrogen induced cracking and method for manufacturing same - Google Patents

Heavy-wall steel plate having 450mpa-grade tensile strength and excellent resistance to hydrogen induced cracking and method for manufacturing same Download PDF

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US20190382865A1
US20190382865A1 US16/471,268 US201716471268A US2019382865A1 US 20190382865 A1 US20190382865 A1 US 20190382865A1 US 201716471268 A US201716471268 A US 201716471268A US 2019382865 A1 US2019382865 A1 US 2019382865A1
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steel plate
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heavy
wall steel
induced cracking
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Seong-Ung Koh
Yoen-Jung PARK
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Posco Holdings Inc
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Posco Co Ltd
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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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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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    • 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
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    • 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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    • C22C38/18—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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    • 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
    • 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
    • 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 disclosure relates to a heavy-wall steel plate having excellent resistance to hydrogen induced cracking, and a method for manufacturing the same, and, in particular, to a normalizing heat treated heavy-wall steel plate having a thickness of 40 mm or more and having a tensile strength of 450 MPa, and a method for manufacturing the same.
  • a heavy-wall steel plate for guaranteeing hydrogen induced cracking according to American Petroleum Institute (API) standard has been used for line pipe, process pipe, or the like, and the required properties and manufacturing process of a steel material has been used determined, depending on the usage environment.
  • API American Petroleum Institute
  • the manufacturing process of a steel material requires a heat treatment process such as a normalizing process, a quenching/tempering process, or the like.
  • a heat treatment steel plate requires a normalizing steel material.
  • the normalizing steel material is generally low in strength due to the characteristics of the air-cooling material, and when the content of the alloying elements such as C, Mn, and the like, increases in order to facilitate an increase in strength, the resistance to hydrogen induced cracking may decrease sharply.
  • the reason is that the content of pearlite in the steel plate increases with the addition of C, Mn, and the like, and the resistance to hydrogen induced cracking decreases sharply over a certain percentage of the pearlite fraction.
  • the resistance to hydrogen induced cracking is reduced after the tubing of the steel pipe due to the characteristics of the normalized steel material, the requirements for resistance to hydrogen induced cracking have become stricter in recent years.
  • Korean Patent Publication No. 2004-0021117 proposes a steel material for a pressure vessel having a tensile strength of 600 MPa, which is excellent in toughness and used for materials such as boilers of a power plant, pressure vessels, or the like.
  • the steel material for a pressure vessel proposed by the Patent Publication has a composition comprising, by weight, carbon (C): 0.08% to 0.16%, silicon (Si): 0.1% to 0.4%, manganese (Mn): 0.8% to 1.8%, molybdenum (Mo): 0.2% to 0.8%, nickel (Ni): 0.3% to 0.8%, boron (B): 0.0005% to 0.003%, titanium (Ti): 0.005% to 0.025%, aluminum (Al): 0.01% to 0.08%, phosphorus (P): 0.010% or less, sulfur (S): 0.010% or less, nitrogen (N): 0.010% or less, a balance of iron (Fe), and other unavoidable impurities.
  • the steel material is heat-treated at a temperature in a range of Ac3 to 930° C., and, then, forcibly cooled to room temperature at a cooling rate of 0.5 to 5° C./sec.
  • the Patent Publication relates to a steel material for a pressure vessel having a tensile strength of 600 MPa and a manufacturing method thereof.
  • Korean Patent No. 0833070 proposes a heavy-wall steel plate for a pressure vessel excellent in resistance to hydrogen induced cracking while satisfying a tensile strength of 500 MPa.
  • a steel material having a composition comprising, by weight, carbon (C): 0.1% to 0.30%, silicon (Si): 0.15% to 0.40%, manganese (Mn): 0.6% to 1.2%, phosphorus (P): 0.035% or less, sulfur (S): 0.020% or less, aluminum (Al): 0.001% to 0.05%, chromium (Cr): 0.35% or less, nickel (Ni): 0.5% or less, copper (Cu): 0.5% or less, molybdenum (Mo): 0.2% or less, vanadium (V): 0.05% or less, niobium (Nb): 0.05% or less, calcium (Ca): 0.0005% to 0.00
  • Equation 1 Cu+Ni+Cr+Mo ⁇ 1.5%
  • Equation 2 Cr+Mo ⁇ 0.4%
  • Equation 3 V+Nb ⁇ 0.1%
  • Equation 4 Ca/S>1.0, as relationships for components.
  • the above patent relates to a method for manufacturing the steel material having a tensile strength of 500 MPa, as described above, comprising: reheating the steel material at 1050° C. to 1250° C.; performing a recrystallization controlled rolling operation of hot-rolling the reheated steel material at a temperature not lower than a non-recrystallization temperature; and performing a normalizing operation of heat treating the hot-rolled steel material at a temperature of 850° C. to 950° C. at 1.3 ⁇ t+(10-30 minutes) (where t denotes a thickness (mm) of a steel material).
  • the present disclosure is made to solve the above problems of the prior art, and it is an object of the present disclosure to optimize components in steel, a microstructure of the steel, a rolling operation, a cooling operation, and a heat treatment operation, to provide a normalizing heat treated heavy-wall steel plate having excellent resistance to hydrogen induced cracking, having a thickness of 40 mm or more and having a tensile strength of 450 MPa.
  • the heat treatment operation is performed at a temperature higher than that of a conventional normalizing heat treatment operation without including expensive precipitation-type elements such as Cr, Mo, V, etc., to provide a normalizing heat treated heavy-wall steel plate having excellent resistance to hydrogen induced cracking, and having a tensile strength of 450 MPa.
  • a heavy-wall steel plate having excellent resistance to hydrogen induced cracking includes, by weight, carbon (C): 0.03% to 0.06%, silicon (Si): 0.2% to 0.4%, manganese (Mn): 1.0% to 1.6%, phosphorus (P): 0.03% or less, sulfur (S): 0.003% or less, aluminum (Al): 0.06% or less, nitrogen (N): 0.01% or less, copper (Cu): 0.05% to 0.4%, nickel (Ni): 0.05% to 0.5%, calcium (Ca): 0.0005% to 0.003%, a balance of iron (Fe), and other unavoidable impurities, wherein a thickness of the heavy-wall steel plate is 40 mm or more, and tensile strength of the heavy-wall steel plate is 450 MPa or more.
  • the heavy-wall steel plate may further include niobium (Nb): 0.005% to 0.05% and titanium (Ti): 0.005% to 0.03%.
  • the heavy-wall steel plate may be a microstructure having a composite structure of ferrite and pearlite, and an area fraction of the pearlite may be less than 10%.
  • the heavy-wall steel plate may further include Al—Ca-based inclusions, and a minimum distance between Al—Ca-based inclusions having a diameter of 2 ⁇ m or more may be 100 ⁇ m or more in a rolling direction.
  • a method for manufacturing a heavy-wall steel plate having 450 MPa-grade tensile strength and excellent resistance to hydrogen induced cracking includes:
  • a slab having a composition comprising, by weight, carbon (C): 0.03% to 0.06%, silicon (Si): 0.2% to 0.4%, manganese (Mn): 1.0% to 1.6%, phosphorus (P): 0.03% or less, sulfur (S): 0.003% or less, aluminum (Al): 0.06% or less, nitrogen (N): 0.01% or less, copper (Cu): 0.05% to 0.4%, nickel (Ni): 0.05% to 0.5%, calcium (Ca): 0.0005% to 0.003%, a balance of iron (Fe), and other unavoidable impurities;
  • a steel plate having excellent resistance to hydrogen induced cracking having a thickness of 40 mm or more, and having a tensile strength of 450 MPa, at relatively low manufacturing costs.
  • FIG. 1 is a graph illustrating distribution of tensile strengths according to normalizing temperatures of Comparative Examples 5 to 10, having the same components as those of Inventive Example 1.
  • FIG. 2 is a photograph showing Al—Ca-based inclusions in a hydrogen induced cracking fracture surface of Comparative Example 7 (low-temperature rolled material).
  • the present inventors have found that Cr, Mo, V, and the like, which are commonly used in conventional normalized steels, have no effect on strength improvement, while alloying elements such as C, Si, Mn, Cu, and the like have a great influence on the strength improvement of normalized steel.
  • alloying elements such as C, Si, Mn, Cu, and the like have a great influence on the strength improvement of normalized steel.
  • C and Mn are the most influential elements for deterioration of resistance to hydrogen induced cracking
  • Si and Cu are the most influential elements for deterioration of resistance to hydrogen induced cracking
  • the additional effect of Si and Cu may improve soft matrix structure, which is vulnerable to hydrogen induced cracking of low strength steel materials by strengthening the ferrite matrix phase.
  • the present inventors have found that hydrogen induced cracking generated in low strength steel has a close relationship to distribution of inclusions contained in the steel, and consequently, a method of restricting the distribution of inclusions has been envisaged.
  • the normalized steel material has been subjected to high-temperature general rolling in terms of manufacturing cost, but has a characteristic that the finishing rolling temperature decreases as the thickness of the steel material decreases. Also, as a thickness of the steel material is reduced or a thickness of the slab is increased, the total thickness of the steel material for securing the product thickness may increase.
  • the finishing rolling temperature is limited to a certain level or more, and the slab thickness before the slab reheating is optimized, to limit the total rolling reduction thickness, on the basis of the findings that, as the finish rolling temperature decreases or the total rolling reduction thickness increases, resistance to hydrogen induced cracking of the normalized steel material is reduced.
  • a method of refining the austenite grains is generally used in which the content of C, Mn, and the like is added or the normalizing temperature is decreased.
  • the content is added, resistance to hydrogen induced cracking may decrease, and a sufficient increase in strength may not be expected only through decreasing the normalizing temperature.
  • a normalizing temperature of at least the general level is proposed to maximize the effect of increasing quenchability due to grain coarsening, based on the fact that austenite grains are coarsened by increasing the normalizing temperature.
  • C is closely related to the manufacturing method together with other components.
  • C has a greatest influence on the characteristics of the steel material.
  • the content of C is less than 0.03 wt %, it may be difficult to secure sufficient strength, and a welding heat-affected zone may be softened more than necessary.
  • the content of C is more than 0.06 wt %, the resistance to hydrogen induced cracking of the steel plate may be decreased, and weldability may be deteriorated. Therefore, it is preferable to limit the content of C to 0.03-0.06 wt %.
  • Si not only acts as a deoxidizer in a steel manufacturing process, but also serves to raise the strength of the steel material.
  • the content of Si is less than 0.2 wt %, it may be difficult to secure sufficient strength.
  • the content of Si is more than 0.4 wt %, weldability is lowered, and scale peelability is caused upon rolling. Therefore, it is preferable to limit the content to 0.2 wt to 0.4 wt %.
  • Mn may be an element for improving the strength of the steel by lowering the ferrite transformation temperature until a certain amount is added, without impairing impact toughness, and is preferably added in an amount of 1.0 wt % or more. When it is added in an amount exceeding 1.6% by weight, there is a problem that center segregation may occur to decrease the resistance to hydrogen induced cracking sharply. Therefore, the content thereof is preferably limited to 1.0 wt % to 1.6 wt %.
  • P is an impurity element, and when the content is more than 0.03 wt %, weldability is significantly decreased, and also impact toughness is decreased, and thus, it is preferable to limit the content to 0.03 wt % or less. In particular, 0.01 wt % or less is more preferable in terms of low-temperature impact toughness.
  • S is also an impurity element, and when the content is more than 0.003 wt %, the ductility, impact toughness, and weldability of steel are decreased. Therefore, it is preferable to limit the content to 0.003 wt % or less. In particular, since S is bonded to Mn to form a MnS inclusion, and decrease the low-temperature impact toughness of steel, 0.002 wt % or less is more preferable.
  • Al may serve as a deoxidizer which reacts with oxygen present in molten steel to remove oxygen. Therefore, it is general to add Al in an amount to provide a steel material with sufficient deoxidation ability. When added more than 0.06 wt %, a large amount of an oxide-based inclusion is formed to inhibit the impact toughness of a material, and thus, the content is limited to 0.06 wt % or less.
  • N Since it is difficult to industrially completely remove N from steel, the upper limit thereof is 0.01 wt % which may be allowed in a manufacturing process. N may form nitrides with Al, Ti, Nb, V, etc., to inhibit austenite crystal grin growth, and to help toughness and strength improvement, however, when the content thereof exceeds 0.01%, N is present in a solid-soluble state and N in a solid-soluble state has an adverse influence on low temperature toughness. Therefore, it is preferable to limit the content thereof to 0.01% or less.
  • Cu may be an element for improving the strength of ferrite through solid solution strengthening, and should be added in an amount of 0.05% or more. Since Cu is an element which causes cracks on the surface during a hot-rolling operation to hinder the surface quality, it is preferable to restrict the upper limit thereof to 0.4%.
  • Ni may be an element which improves the toughness of steel, and is preferably added in an amount of 0.05% or more, to reduce surface cracks generated during a hot-rolling operation of Cu-added steel.
  • the Ni content of 0.5% or more may increase price of the steel material. Therefore, it is preferable to restrict the upper limit thereof to 0.5%.
  • Ca may serve to spheroidize MnS inclusions.
  • MnS an inclusion having a relatively low melting point, produced in the central portion, may be stretched upon rolling to be present as a stretched inclusion in the central portion of steel.
  • MnS is present in a relatively large amount and partially dense, it may serve to decrease elongation when stretched in a thickness direction.
  • the added Ca may react with MnS to surround MnS, thereby interfering with the stretching of MnS.
  • Ca should be added in an amount 0.0005 wt % or more. Since Ca has high volatility and thus, has a relatively low yield, considering the load produced in the steel manufacturing process, it is preferable to restrict the upper limit thereof to 0.003 wt % or less.
  • the steel plate of the present disclosure may further include Nb and Ti optionally in addition to the above-mentioned composition.
  • Nb may be solid-solubilized when reheating a slab, and may inhibit austenite crystal grain growth during a hot rolling operation, and, then, may be precipitated to improve the strength of steel to 0.005% or more.
  • Nb When Nb is added in an excess amount exceeding 0.05%, it is precipitated together with Ti in the central portion to induce hydrogen induced cracking, such that the upper limit of Nb is limited to 0.05% in the present disclosure.
  • Ti may be an element effective in inhibiting the growth of austenite crystal grains by being bonded to N when reheating the slab to form TiN.
  • the upper limit of Ti is limited to 0.03% in the present disclosure. From the viewpoint of low-temperature toughness, it is more preferable to add 0.01% or less.
  • the steel plate of the present disclosure may further include Fe and unavoidable impurities, and does not exclude the addition of other components in addition to the above-described components.
  • the steel plate of the present disclosure may additionally include other components in addition to the above-mentioned components in the composition of steel.
  • the steel having the above composition may have different microstructures depending on the contents of the elements, rolling operations, cooling conditions, and heat treatment conditions, and may affect strength and resistance to hydrogen induced cracking depending on the microstructure even with the same composition.
  • a microstructure of a normalized steel material of the present disclosure having excellent resistance to hydrogen induced cracking, having a thickness of 40 mm or more, and having a tensile strength of 450 MPa, will be described.
  • the steel plate having excellent resistance to hydrogen induced cracking may be a steel plate having a thickness of 40 mm or more, and may be a steel plate having excellent in resistance to hydrogen induced cracking while maintaining a relatively high strength of 450 MPa or more in tensile strength, regardless of its thickness.
  • a normalized steel has two phases of ferrite and pearlite as its matrix structure without adding excessive components.
  • a pearlite fraction in the matrix structure is 10% or more, since resistance to hydrogen induced cracking is lowered, the pearlite fraction in the present disclosure may be limited to less than 10%.
  • the Al—Ca-based inclusions may be a factor deteriorating the resistance to hydrogen induced cracking of low strength steel.
  • the minimum distance between Al—Ca-based inclusions having a diameter of 2 ⁇ m or more in a rolling direction is less than 100 ⁇ m, the resistance to hydrogen induced cracking may be deteriorated. It is preferable that a lower limit in the minimum distance between the Al—Ca-based inclusions having a diameter of 2 ⁇ m or more be limited to 100 ⁇ m.
  • a steel slab having the above-mentioned composition may be prepared, and, then, may be reheated in a temperature range of 1100° C. to 1300° C.
  • the reheating process is an operation of heating the steel slab to a relatively high temperature, to hot-roll the steel slab.
  • the reheating temperature is higher than the upper limit of 1300° C. defined by the present disclosure, the austenite crystal grains may be excessively coarsened to lower the strength of steel, and to generate scale defects.
  • the reheating temperature is less than 1100° C., re-solid soluble ratio of the alloying elements may decrease. Accordingly, in the present disclosure, the range of the reheating temperature is preferably limited to 1100° C. to 1300° C., and more preferably 1100° C. to 1180° C. in terms of strength and toughness.
  • the heated slab may be hot-rolled such that the total rolling reduction thickness is less than 200 mm at a finish rolling temperature of 900° C. or higher, so as to prepare a hot-rolled steel plate.
  • the finish rolling temperature is lower than 900° C.
  • large Al—Ca-based inclusions may be divided in the rolling direction, such that a minimum distance between Al—Ca-based inclusions having a diameter of 2 ⁇ m or more is less than 100 ⁇ m. Therefore, since the resistance to hydrogen induced cracking in the steel may be rapidly deteriorated, it is preferable to hot-roll the heated slab that the total rolling reduction thickness in the present disclosure is limited to be less than 200 mm.
  • the crystal grains may be finer and the low-temperature toughness may be improved.
  • the total rolling reduction thickness of the slab is 200 mm or more, the Al—Ca-based inclusions of a normalizing steel material may be easily divided in the rolling direction during a rolling operation, such that a minimum distance between Al—Ca-based inclusions having a diameter of 2 ⁇ m or more is less than 100 ⁇ m. Therefore, since the resistance to hydrogen induced cracking in the steel may be rapidly deteriorated, it is preferable to hot-roll the heated slab that the total rolling reduction thickness in the present disclosure is limited to be 200 mm or less.
  • the hot-rolled steel plate may be cooled, preferably by air cooling. Since the steel material to be provided is subjected to a heat treatment after rolling, the cooling process is not an important process variable, but when the steel plate is water cooled from a relatively high temperature, it may cause shape deformation and productivity resistance of the steel plate.
  • the hot-rolled steel plate is subjected to a normalizing treatment in a temperature range of 1000° C. to 1100° C.
  • the normalizing temperature refers to a temperature at which the cooled steel plate is reheated to the austenite region at a certain temperature or more after the hot-rolling operation, and an air cooling operation may perform after the heating operation.
  • the normalizing temperature may be performed directly on the Ar3 temperature. Since the normalizing temperature range proposed in this study is aimed at coarsening crystal grain through the austenite crystal grain growth, it may deviate from the normal normalizing temperature.
  • the austenite crystal grains when the normalizing temperature is less than 1000° C., the austenite crystal grains may be not sufficiently coarsened. Therefore, no sufficient quenchability may be secured at the time of the air cooling operation, and ferrite and pearlite formed at the time of the air cooling operation may not be completely transformed into austenite phase.
  • the normalizing temperature exceeds 1100° C., the austenite crystal grains may be excessively coarsened. Therefore, the low-temperature toughness may deteriorate and a high-temperature scale may be caused on the surface of the steel.
  • the range of the normalizing reheating temperature is preferably limited to 1000° C. to 1100° C.
  • the steel types illustrated in the following Table 1 were prepared to produce steel plates according to the manufacturing process conditions illustrated in the following Table 2. Specifically, the steel slab having the composition illustrated in the following Table 1 was heated to the heating temperature illustrated in the following Table 2, rolled to the finish rolling temperature and the total rolling reduction thickness illustrated in the following Table 2, reheated to the reheating temperature illustrated in the following Table 2, and then air-cooled.
  • a pearlite area fraction, a distance between the Al—Ca-based inclusions, tensile strength, and a hydrogen induced cracking sensitivity, e.g., a crack length ratio (CLR) were measured for the thus prepared steel plate, and the results are illustrated in the following Table 3.
  • the pearlite area fraction and the distance between the Al—Ca-based inclusions were obtained by observing the microstructure of the steel plate, and the hydrogen induced cracking sensitivity (CLR) was tested according to the method specified by a National Association of Corrosion Engineers (NACE), and percentage of the length of the hydrogen induced cracking generated with respect to the entire length of the specimen.
  • CLR hydrogen induced cracking sensitivity
  • Comparative Examples 1 to 4 are comparative examples in which the components having steel composition and the manufacturing process conditions fail to satisfy the ranges according to an aspect of the present disclosure
  • Comparative Examples 5 to 10 are comparative examples in which the components having steel composition satisfy the ranges according to an aspect of the present disclosure, but the manufacturing process conditions fail to satisfy the ranges according to an aspect of the present disclosure.
  • Inventive Examples 1 and 2 satisfying the steel composition and the manufacturing process conditions according to an aspect of the present disclosure have a tensile strength of 450 MPa or more and a hydrogen induced cracking sensitivity (CLR) of 1% or less, and, thus, it can be seen that resistance to hydrogen induced cracking thereon is excellent.
  • CLR hydrogen induced cracking sensitivity
  • Comparative Examples 1 to 10 which fail to satisfy one of the component system, component range, and process conditions according to an aspect of the present disclosure, have a tensile strength of less than 450 MPa, or a hydrogen induced cracking sensitivity (CLR) exceeding 1%, and, thus, it can be seen that resistance to hydrogen induced cracking thereon was not sufficient.
  • CLR hydrogen induced cracking sensitivity
  • a steel plate having excellent resistance to hydrogen induced cracking having a thickness of 40 mm or more, and having a tensile strength of 450 MPa, may be obtained by manufacturing the steel plate according to the composition and manufacturing process of the present disclosure.

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114737027A (zh) * 2022-04-15 2022-07-12 首钢集团有限公司 抗氢致开裂性能优异的345MPa级容器钢及其制备方法

Family Cites Families (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH075968B2 (ja) * 1990-02-13 1995-01-25 新日本製鐵株式会社 耐水素誘起割れ性、耐硫化物応力腐食割れ性および低温靭性に優れた鋼板の製造方法
JP4123597B2 (ja) * 1998-09-30 2008-07-23 住友金属工業株式会社 強度と靱性に優れた鋼材の製造法
JP3633515B2 (ja) * 2001-06-12 2005-03-30 住友金属工業株式会社 耐水素誘起割れ性に優れた熱延鋼板およびその製造方法
JP3758581B2 (ja) * 2002-02-04 2006-03-22 住友金属工業株式会社 低炭素快削鋼
KR100928796B1 (ko) 2002-09-02 2009-11-25 주식회사 포스코 인성이 우수한 인장강도 600ＭＰａ급 압력용기용 강의제조방법
WO2004022807A1 (ja) * 2002-09-04 2004-03-18 Jfe Steel Corporation 大入熱溶接用鋼材およびその製造方法
CN100420758C (zh) * 2002-10-01 2008-09-24 住友金属工业株式会社 具有优异抗氢致开裂性的高强度无缝钢管及其制备方法
JP4725437B2 (ja) * 2006-06-30 2011-07-13 住友金属工業株式会社 厚鋼板用連続鋳造鋳片及びその製造方法並びに厚鋼板
KR100833070B1 (ko) 2006-12-13 2008-05-27 주식회사 포스코 내ｈｉｃ특성이 우수한 인장강도 500㎫급 압력용기용 강판및 그 제조 방법
JP5423323B2 (ja) * 2009-02-12 2014-02-19 新日鐵住金株式会社 耐水素誘起割れ性に優れた高強度ラインパイプ用鋼板及び高強度ラインパイプ用鋼管
KR101271954B1 (ko) * 2009-11-30 2013-06-07 주식회사 포스코 저온인성 및 수소유기균열 저항성이 우수한 압력용기용 강판 및 그 제조방법
JP5853661B2 (ja) * 2011-12-15 2016-02-09 Ｊｆｅスチール株式会社 高強度耐サワーラインパイプ用鋼板、その素材及び高強度耐サワーラインパイプ用鋼板の製造方法
CN104024461B (zh) * 2012-03-30 2016-04-06 新日铁住金株式会社 抗氢诱发裂纹性优良的高强度管道用钢管和其所使用的高强度管道用钢板、以及它们的制造方法
KR20140002256A (ko) * 2012-06-28 2014-01-08 현대제철 주식회사 비조질강 및 그 제조 방법
JP5928405B2 (ja) * 2013-05-09 2016-06-01 Ｊｆｅスチール株式会社 耐水素誘起割れ性に優れた調質鋼板及びその製造方法
CN103276293A (zh) * 2013-06-07 2013-09-04 南京钢铁股份有限公司 一种优异抗氢致开裂性管线钢板的生产方法
KR20160078844A (ko) * 2014-12-24 2016-07-05 주식회사 포스코 수소유기균열 저항성이 우수한 후판 강재 및 그 제조방법

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114737027A (zh) * 2022-04-15 2022-07-12 首钢集团有限公司 抗氢致开裂性能优异的345MPa级容器钢及其制备方法

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