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EP3943621A1 - Matériau de base destiné à de l'acier plaqué, acier plaqué et procédé de fabrication d'acier plaqué - Google Patents

Matériau de base destiné à de l'acier plaqué, acier plaqué et procédé de fabrication d'acier plaqué Download PDF

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Publication number
EP3943621A1
EP3943621A1 EP20772572.2A EP20772572A EP3943621A1 EP 3943621 A1 EP3943621 A1 EP 3943621A1 EP 20772572 A EP20772572 A EP 20772572A EP 3943621 A1 EP3943621 A1 EP 3943621A1
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EP
European Patent Office
Prior art keywords
clad steel
less
base metal
steel
clad
Prior art date
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EP20772572.2A
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German (de)
English (en)
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EP3943621A4 (fr
Inventor
Takashi Kawamura
Kenta NISHIMOTO
Daishiro SUZUKI
Kunihiko Hashi
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Japan Steel Works M&E Inc
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Japan Steel Works M&E Inc
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Publication of EP3943621A1 publication Critical patent/EP3943621A1/fr
Publication of EP3943621A4 publication Critical patent/EP3943621A4/fr
Pending legal-status Critical Current

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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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • 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
    • C21D2251/00—Treating composite or clad material
    • C21D2251/02—Clad material

Definitions

  • the present invention relates to a base metal for clad steel used for a clad material, a clad steel including the base metal for clad steel, and a method for producing the same.
  • Patent Literature 1 discloses a steel sheet which consists of martensite-austenite constituent with an area fraction of 2% to 15% and bainite structure of a base metal of a clad steel sheet by accelerated cooling from a temperature of Ar 3 -10°C or more to a cooling stop temperature of 500°C to 650°C at a cooling rate of 5°C/s or more after hot rolling, and then immediately performing reheating to 550°C to 750°C at a heating rate of 0.5°C/s or more.
  • Patent Literature 1 JP-A-2015-224376
  • Patent Literature 1 has a problem in that the yield ratio of the base metal of the clad steel sheet is increased by reheating after accelerated cooling. Furthermore, there is a problem in that cracking occurs during welding or weldability is deteriorated.
  • an object of the present invention is to provide a base metal for clad steel having excellent low-temperature toughness and a low yield ratio, and a clad steel including the base metal.
  • a base metal for clad steel includes a composition containing: in terms of mass%, C of 0.04% to 0.10%; Si of 0.10% to 0.30%; Mn of 1.30% to 1.60%; P of 0.015% or less; S of 0.005% or less; Ni of 0.10% to 0.50%; Cr of 0.10% or less; Cu of 0.05% or less; Mo of 0.05% to 0.40%; V of 0.02% to 0.06%; Nb of 0.03% or less; Ti of 0.005% to 0.025%; Al of 0.020% to 0.050%; N of 0.0030% to 0.0100%; and the balance being Fe and unavoidable impurities.
  • a carbon equivalent Ceq according to the following formula (1) is 0.400 or less, and a yield ratio Y.R. according to the following formula (2) is less than 0.80.
  • Ti/N which is a mass ratio of Ti content to N content, is in a range of 1.5 to 4.0.
  • the carbon equivalent according to the above formula (1) is 0.330 ⁇ Ceq ⁇ 0.400, and weld cracking sensitivity Pcm according to the following formula (3) is within a range of 0.200 or less.
  • Pcm C + Si / 30 + Mn / 20 + Ni / 60 + Cr / 20 + Cu / 20 + Mo / 15 + V / 10 mass %
  • a cladding material is cladded on the base metal for clad steel according to any one of the above embodiments.
  • a method for producing a clad steel according to one embodiment of the present invention includes: melting an alloy steel for a base metal for clad steel to form a steel ingot; subjecting the steel ingot to clad rolling with a cladding material; quenching the clad steel from an austenitizing temperature range of 900°C to 980°C; and not tempering the clad steel, in which the base metal for clad steel includes a composition containing: in terms of mass%, C of 0.04% to 0.10%; Si of 0.10% to 0.30%; Mn of 1.30% to 1.60%; P of 0.015% or less; S of 0.005% or less; Ni of 0.10% to 0.50%; Cr of 0.10% or less; Cu of 0.05% or less; Mo of 0.05% to 0.40%; V of 0.02% to 0.06%; Nb of 0.03% or less; Ti of 0.005% to 0.025%; Al of 0.020% to 0.050%; N of 0.0030% to 0.0100%
  • a base metal for clad steel having excellent low-temperature toughness and a low yield ratio can be obtained.
  • the base metal for clad steel can be produced, for example, only by quenching after hot rolling, and a low yield ratio can be achieved.
  • large-scale equipment such as controlled rolling is not required, and economic efficiency can be improved.
  • FIG. 1 is a schematic view showing a clad steel 10 according to an embodiment of the present invention, a base metal 11 for clad steel according to the embodiment of the present invention and a cladding material 12 which constitute the clad steel 10.
  • a base metal 11 for clad steel constitutes a clad steel 10 together with a cladding material 12.
  • the base metal for clad steel will be described.
  • a base metal for clad steel includes a composition containing: in terms of mass%, C: 0.04% to 0.10%; Si: 0.10% to 0.30%; Mn: 1.30% to 1.60%; P: 0.015% or less; S: 0.005% or less; Ni: 0.10% to 0.50%; Cr: 0.10% or less; Cu: 0.05% or less; Mo: 0.05% to 0.40%; V: 0.02% to 0.06%; Nb: 0.03% or less; Ti: 0.005% to 0.025%; Al: 0.020% to 0.050%; N: 0.0030% to 0.0100%; and the balance being Fe and unavoidable impurities.
  • a carbon equivalent Ceq according to the following formula (1) is 0.400 or less, and a yield ratio (Y.R.) according to the following formula (2) is less than 0.80.
  • Ceq C + Mn / 6 + Ni + Cu / 15 + Cr + Mo + V / 5 mass %
  • Y . R . Y . S . MPa ; 0.5 % Under load / T . S . MPa
  • compositions and the like of the base metal for clad steel according to one embodiment of the present invention will be described.
  • “%” in the composition range means “mass%”.
  • a lower limit of the content of C in the base metal for clad steel is 0.04%.
  • the lower limit is preferably 0.045%, and more preferably 0.05%.
  • an upper limit of the content of C in the base metal for clad steel is 0.10%.
  • the upper limit is preferably 0.08%, and more preferably 0.07%.
  • Si has a deoxidizing action at the time of melting steel, and needs to be contained in a predetermined amount or more in order to obtain sound steel.
  • Si is an element necessary for ensuring strength. Therefore, a lower limit of the content of Si in the base metal for clad steel is 0.10%. The lower limit is preferably 0.11%, and more preferably 0.12%.
  • an upper limit of the content of Si in the base metal for clad steel is 0.30%.
  • the upper limit is preferably 0.20%, and more preferably 0.18%.
  • Mn is useful as a deoxidizing element similarly to Si, and contributes to improvement in hardenability of steel.
  • a lower limit of the content of Mn in the base metal for clad steel is 1.30%.
  • the lower limit is preferably 1.35%, and more preferably 1.40%.
  • an upper limit of the content of Mn in the base metal for clad steel is 1.60%.
  • the upper limit is preferably 1.57%, and more preferably 1.55%.
  • P is preferably contained as an impurity in a smaller amount in the base metal for clad steel, but an upper limit thereof is 0.015% which can be industrially realized.
  • the upper limit is preferably 0.013%, and more preferably 0.012%.
  • S is preferably contained as an impurity in a smaller amount in the base metal for clad steel, but an upper limit thereof is 0.005% which can be industrially realized.
  • the upper limit is preferably 0.003% or less, and more preferably 0.002%.
  • Ni is an element necessary for securing strength by improving hardenability, and low-temperature toughness. Therefore, a lower limit of the content of Ni in the base metal for clad steel is 0.10%. For the same reason, the lower limit is preferably 0.15%, and more preferably 0.20%.
  • an upper limit of the Ni content in the base metal for clad steel is 0.50%.
  • the upper limit is preferably 0.35%, and more preferably 0.33%.
  • an upper limit of the Cr content in the base metal for clad steel is 0.10%.
  • the upper limit is preferably 0.05%, and more preferably 0.03%.
  • a lower limit is not particularly limited, but is, for example, 0.01%.
  • an upper limit of the content of Cu in the base metal for clad steel is 0.05%.
  • the upper limit is preferably 0.03%, and more preferably 0.02%.
  • a lower limit is not particularly limited, but is, for example, 0.005%.
  • Mo is an element that improves the hardenability and improves the strength of the base metal after quenching, but when Mo is less than 0.05%, the effect cannot be sufficiently obtained. Therefore, a lower limit of the content of Mo in the base metal for clad steel is 0.05%. For the same reason, the lower limit is preferably 0.08%, and more preferably 0.10%.
  • an upper limit of the content of Mo in the base metal for clad steel is 0.40%.
  • the upper limit is preferably 0.20%, and more preferably 0.18%.
  • V 0.02% to 0.06%
  • V is an important element for ensuring the strength of steel.
  • V has an effect of securing T.S. to be described later, contributes to refinement of crystal grains, and has an effect of securing impact characteristics without tempering.
  • a lower limit of the content of V in the base metal for clad steel is 0.02%.
  • the lower limit is preferably 0.023%, and more preferably 0.025%.
  • an upper limit of the content of V in the base metal for clad steel is 0.06%.
  • the upper limit is preferably 0.05%, and more preferably 0.04%.
  • Nb is effective in preventing coarsening of austenite grains and in improving refinement of crystal grains and strength by uniformly dispersing fine Nb carbides and the like in a base metal when steel is heated to a quenching temperature.
  • an upper limit of the Nb content in the base metal for clad steel is 0.03%.
  • the upper limit is preferably 0.028%, and more preferably 0.027%.
  • a lower limit is not particularly limited, but is, for example, 0.005%.
  • Ti has an effect of forming carbides and nitrides finely dispersed in steel and refining austenite grains.
  • nitride formed by bonding with N has an effect of preventing coarsening of crystal grains in a heat-affected zone at the time of welding. Therefore, when the content of Ti is less than 0.005%, the above effect is small. When the content of Ti exceeds 0.025%, the toughness is greatly deteriorated due to a notch effect due to aggregation and coarsening of carbides and nitrides.
  • a lower limit of the Ti content in the base metal for clad steel is 0.005%.
  • the lower limit is preferably 0.010%, and more preferably 0.012%.
  • An upper limit of the Ti content in the base metal for clad steel is 0.025%.
  • the upper limit is preferably 0.020%, and more preferably 0.018%.
  • Al is an element effective as a deoxidizing agent. Precipitated AlN prevents coarsening of austenite grains during quenching, but when Al is less than 0.020%, the effect cannot be sufficiently obtained. Therefore, a lower limit of the content of Al in the base metal for clad steel is 0.020%. For the same reason, the lower limit is preferably 0.023%, and more preferably 0.025%.
  • an upper limit of the Al content in the base metal for clad steel is 0.050%.
  • the upper limit is preferably 0.040%, and more preferably 0.035%.
  • N reacts with Ti and precipitates as TiN in steel, which is effective for refinement of crystal grains. Since TiN has high solute temperature and stably exists even at a relatively high temperature, it is very effective to prevent coarsening of crystal grains in the heat-affected zone and improve the toughness of the heat-affected zone. On the other hand, when the addition amount is too small, a sufficient effect cannot be obtained. Therefore, a lower limit of the content of N in the base metal for clad steel is 0.0030%. For the same reason, the lower limit is preferably 0.0035%, and more preferably 0.0040%.
  • an upper limit of the content of N in the base metal for clad steel is 0.0100%.
  • the upper limit is preferably 0.0080%, and more preferably 0.0070%.
  • the balance other than the above elements is Fe and unavoidable impurities.
  • the unavoidable impurities include O and H.
  • the mass ratio of Ti/N is adjusted as desired.
  • a lower limit of the mass ratio of Ti/N is 1.5, a sufficient effect of preventing coarsening of crystal grains can be obtained.
  • the lower limit is more preferably 1.7, and still more preferably 2.0.
  • an upper limit of the mass ratio of Ti/N is 4.0, it is possible to prevent a decrease in the toughness of the base metal due to excessive precipitation of TiN and coarsening of TiN.
  • the upper limit is more preferably 3.9, and still more preferably 3.85.
  • the base metal for clad steel according to the present embodiment has a carbon equivalent Ceq: 0.400 or less. The reason why the carbon equivalent is limited will be described below.
  • Alloy elements are added in order to improve the hardenability of steel and provide desired strength, toughness, and other properties.
  • it is necessary to increase the amount of alloy elements to be added.
  • an increase in the amount of alloy elements to be added is effective for increasing the strength, in the heat treatment, when the carbon equivalent is too high, the strength becomes too high and the yield ratio is increased. Therefore, an upper limit of the carbon equivalent (Ceq) represented by the following formula (1) is 0.400.
  • Ceq C + Mn / 6 + Ni + Cu / 15 + Cr + Mo + V / 5 mass %
  • a lower limit of the carbon equivalent is preferably 0.330. That is, it is preferable to satisfy 0.330 ⁇ Ceq ⁇ 0.400.
  • the lower limit of the carbon equivalent (Ceq) is more preferably 0.335, and still more preferably 0.340.
  • An upper limit of the carbon equivalent (Ceq) is preferably 0.390, and more preferably 0.385.
  • the yield ratio Y.R. is less than 0.80 (yield ratio Y.R. ⁇ 0.80). The reason why the yield ratio Y.R. is limited will be described below.
  • the yield ratio is represented by a ratio of T.S. (tensile strength) to Y.S. (MPa; 0.5% Under load) (yield strength), as shown in the following formula (2).
  • T.S. tensile strength
  • Y.S. means 0.5% under load (0.5% under load proof stress), that is, a stress when a total elongation is 0.5% with respect to an elongation gauge length.
  • the yield ratio Y.R. is less than 0.80.
  • Y . R . Y . S . MPa ; 0.5 % Under load / T . S . MPa
  • a lower limit of the yield ratio Y.R is usually 0.60.
  • the T.S (tensile strength) and Y.S (yield strength) can be measured by performing a tensile test at room temperature in accordance with JIS Z2241: 2011 using a No. 10 round bar test piece. Specifically, a test is performed on a test piece having a parallel portion diameter of 12.5 mm and a gauge length of the test piece of 50 mm, and the T.S and Y.S can be obtained from a stress-strain curve.
  • the weld cracking sensitivity Pcm is preferably within a range of 0.200 or less (Pcm ⁇ 0.200). The reason why the weld cracking sensitivity Pcm is limited will be described below.
  • Alloy elements are added in order to improve the hardenability of steel and provide desired strength, toughness, and other properties.
  • it is necessary to increase the amount of the alloy elements to be added.
  • An increase in the amount of the alloy element to be added is effective in increasing the strength, but causes hardening of the heat-affected zone during welding, resulting in occurrence of weld cracking and deterioration of weldability. Therefore, it is preferable to define a component range by the weld cracking sensitivity (Pcm) represented by the following formula (3).
  • Pcm C + Si / 30 + Mn / 20 + Ni / 60 + Cr / 20 + Cu / 20 + Mo / 15 + V / 10 mass %
  • the weld cracking sensitivity Pcm is more preferably 0.195 or less, and still more preferably 0.190 or less.
  • a lower limit is not particularly limited, and is, for example, 0.100.
  • the base metal for clad steel according to the present embodiment is obtained by quenching as described later. The reason why a quenching temperature is limited will be described below.
  • the quenching temperature is a temperature at which a precipitate of a cladding material described later is sufficiently dissolved in solid, and corresponds to a quenchable temperature of the base metal.
  • the lower limit thereof is preferably 900°C.
  • the lower limit is more preferably 910°C, and still more preferably 920°C.
  • an upper limit of the quenching temperature is preferably 980°C in order to prevent the crystal grains of the base metal from becoming coarse and the impact characteristics from deteriorating.
  • the upper limit is more preferably 977°C, and still more preferably 975°C.
  • a heat treatment at the time of producing is only quenching, and tempering is not performed, so that the formation of precipitates by tempering is reduced, and an increase in Y.S. (yield strength) is prevented, thereby realizing a low yield ratio.
  • Y.S. yield strength
  • the clad steel 10 according to the embodiment of the present invention is obtained by cladding the following cladding material 12 on the base metal 11 for clad steel described above.
  • the cladding material is not limited to a specific material.
  • a steel standardized by ISO, JIS, or ASTM is applied.
  • austenitic stainless steels SUS304L, 316L, and 317L, Ni-based alloys Alloy 625 and Alloy 825, and the like can be used.
  • an alloy steel for a base metal for clad steel that includes the following composition is melted to obtain a steel ingot, and then a hot-rolled slab is produced. That is, an alloy steel for a base metal for clad steel is melted by a traditional method to obtain a steel ingot, and a hot-rolled slab is produced, in which the base metal for clad steel contains, in terms of mass%, C: 0.04% to 0.10%, Si: 0.10% to 0.30%, Mn: 1.30% to 1.60%, P: 0.015% or less, S: 0.005% or less, Ni: 0.10% to 0.50%, Cr: 0.10% or less, Cu: 0.05% or less, Mo: 0.05% to 0.40%, V: 0.02% to 0.06%, Nb: 0.03% or less, Ti: 0.005% to 0.025%, Al: 0.020% to 0.050%, N: 0.0030% to 0.0100%, and the balance being Fe and unavoidable impurities.
  • the obtained hot-rolled slab and the cladding material are cladding-rolled.
  • the method of clad rolling is not particularly limited, and any known traditional method can be used.
  • the materials described above can be used as the cladding material.
  • clad rolling and quenching described later can be performed in two overlapped hot-rolled slabs.
  • the conditions for the clad rolling are not particularly limited.
  • the hot-rolled plate is heated to a temperature range of 900°C to 980°C and quenched from an austenite temperature range.
  • the austenite temperature range means a range exceeding a temperature at which a microstructure of steel is an austenite single phase, that is, a temperature at which ferrite transformation starts at the time of cooling.
  • a rising temperature at the time of quenching is not particularly limited.
  • the cooling is preferably performed by water quenching. When a method having a cooling rate lower than that of water quenching, such as oil quenching or FAN cooling, is selected as the cooling method, ferrite may be generated during cooling, and desired strength characteristics may not be obtained.
  • the base metal for clad steel and the clad steel including the base metal for clad steel are obtained.
  • the obtained base metal for clad steel has the yield ratio of Y.R. ⁇ 0.80.
  • a base metal for clad steel according to an embodiment of the present invention was produced as follows.
  • a cladding material is not used, but the presence or absence of the cladding material does not affect the material property evaluation described later, and thus there is no problem in the evaluation of the base metal for clad steel.
  • slabs (steel type A and steel type B) including a composition (mass%, the balance is Fe and other unavoidable impurities) shown in Table 1 were produced by continuous casting, and hot rolling was performed to produce a steel sheet having a thickness of 24 mm on the assumption that the steel sheet was used as a base metal for clad steel. Thereafter, each of the steel sheets obtained from the steel types A and B was quenched at 975°C for 30 minutes to obtain base metals for clad steel in Examples 1 and 2. As a comparative example, after quenching the steel sheet obtained from the steel type A, tempering was performed at three temperatures of 400°C, 500°C, and 580°C for 2 hours to obtain base metals for clad steel in Comparative Examples 1 to 3.
  • a tensile test and a Charpy impact test were performed as the evaluation of the material properties of the obtained base metals for clad steel in Examples and Comparative Examples. Both tests were performed twice for each test material. Test pieces were sampled such that a longitudinal direction of the test pieces was perpendicular to a rolling direction in both the tensile test and the Charpy impact test.
  • the tensile test was performed at room temperature using a No. 10 round bar test piece in accordance with JIS Z2241: 2011.
  • the Charpy impact test was evaluated according to JIS Z2242: 2018 using a test machine having a pendulum hammer with a radius of 2 mm by using a V-notch test piece. Specifically, two tests were performed at -60°C in order to determine the impact characteristics (J) at -60°C by using a V-notch Charpy impact test piece having a square cross section with a length of 55 mm and a side of 10 mm and provided with a V-groove having a notch angle of 45°, a notch depth of 2 mm, and a notch bottom radius of 0.25 mm at a center of the length of the test piece.
  • Example 1 A Only quenching at 975°C 454 575 0.79 375 446 572 0.78 342
  • Example 2 B Only quenching at 975°C 447 590 0.76 485 446 589 0.76 481 Comparative Example 1 A Quenching at 975°C + tempering at 400°C 450 546 0.82 378 449 545 0.82 396 Comparative Example 2 Quenching at 975°C + tempering at 500°C 454 536 0.85 385 449 536 0.84 382 Comparative Example 3 Quenching at 975°C + tempering at 580°C 454 546 0.86 397 449 544 0,85 395
  • Example 1 in which only quenching was performed, the low-temperature toughness was substantially equal to that in the case of performing quenching and tempering treatment, which was good, whereas the yield ratio (Y.R.) could be maintained in a low state of less than 0.80.
  • the present invention relates to a clad steel sheet suitably usable for a pipeline for natural gas transportation.

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EP20772572.2A 2019-03-18 2020-03-17 Matériau de base destiné à de l'acier plaqué, acier plaqué et procédé de fabrication d'acier plaqué Pending EP3943621A4 (fr)

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JP2019049681A JP7281314B2 (ja) 2019-03-18 2019-03-18 クラッド鋼用母材、クラッド鋼およびクラッド鋼の製造方法
PCT/JP2020/011681 WO2020189672A1 (fr) 2019-03-18 2020-03-17 Matériau de base destiné à de l'acier plaqué, acier plaqué et procédé de fabrication d'acier plaqué

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JPS6043433A (ja) * 1983-08-19 1985-03-08 Nippon Kokan Kk <Nkk> 耐食性および靭性に優れたクラツド鋼板の製造方法
JP3699077B2 (ja) * 2002-10-29 2005-09-28 株式会社日本製鋼所 溶接熱影響部の低温靭性に優れたクラッド鋼板用母材および該クラッド鋼板の製造方法
JP4484123B2 (ja) * 2008-02-08 2010-06-16 株式会社日本製鋼所 高強度かつ溶接熱影響部靭性に優れたクラッド鋼板用母材およびその製造方法
KR101301994B1 (ko) * 2011-11-16 2013-09-03 삼성중공업 주식회사 선박용 클래드강 제조 방법
JP6128057B2 (ja) 2014-05-29 2017-05-17 Ｊｆｅスチール株式会社 低ｙｒクラッド鋼板及びその製造方法
US10112254B2 (en) * 2014-08-21 2018-10-30 Huntington Alloys Corporation Method for making clad metal pipe
JP6168131B2 (ja) * 2014-12-09 2017-07-26 Ｊｆｅスチール株式会社 ステンレスクラッド鋼板
JP6648736B2 (ja) * 2017-06-27 2020-02-14 Ｊｆｅスチール株式会社 母材低温靱性とｈａｚ靱性に優れたクラッド鋼板およびその製造方法
JP6861131B2 (ja) 2017-09-12 2021-04-21 Hoya株式会社 内視鏡用対物レンズユニット及び内視鏡

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WO2020189672A1 (fr) 2020-09-24

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