EP3633060B1 - Plaque d'acier et son procédé de fabrication - Google Patents

Plaque d'acier et son procédé de fabrication Download PDF

Info

Publication number
EP3633060B1
EP3633060B1 EP18922100.5A EP18922100A EP3633060B1 EP 3633060 B1 EP3633060 B1 EP 3633060B1 EP 18922100 A EP18922100 A EP 18922100A EP 3633060 B1 EP3633060 B1 EP 3633060B1
Authority
EP
European Patent Office
Prior art keywords
steel plate
less
middle portion
temperature
success
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
EP18922100.5A
Other languages
German (de)
English (en)
Other versions
EP3633060A1 (fr
EP3633060A4 (fr
Inventor
Fumitoshi Takamine
Hitoshi Furuya
Norimasa Kawabata
Takumi MIYAKE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Nippon Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Steel Corp filed Critical Nippon Steel Corp
Publication of EP3633060A1 publication Critical patent/EP3633060A1/fr
Publication of EP3633060A4 publication Critical patent/EP3633060A4/fr
Application granted granted Critical
Publication of EP3633060B1 publication Critical patent/EP3633060B1/fr
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
    • 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
    • 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
    • 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
    • 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
    • C21D8/0273—Final recrystallisation annealing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • 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
    • 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
    • C22C38/46—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
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron

Definitions

  • the present invention relates to a steel plate and a method of manufacturing the same.
  • a huge gear (gear) is used in a rotating mechanism of a large industrial machine represented by a rotary kiln.
  • the steel plate, which is to become a material is required to have hardness and toughness.
  • the steel plate which is to become the material is required to have HB 350 or more in the surface layer and in the thickness middle portion and satisfy vE- 20°C ⁇ 47 J in the thickness middle portion. This is because the properties of the thickness middle portion are important in order to manufacture a gear by machining the steel to the thickness middle portion.
  • Ceq is represented, for example, by Formula (1).
  • the element symbol included in Formula (1) shows the amount (mass%) of the corresponding element in the chemical composition of the steel.
  • Patent Document 1 aims to provide a thick steel plate having a plate thickness of more than 200 mm and a small hardness difference between the surface layer and the center, as a huge gear material used in a rotating mechanism of a large industrial machine, and a method of manufacturing the same, and provides a thick steel plate in which a three-point average of C-direction Charpy at -20°C is 20 J or more in the thickness middle portion, the hardness of the surface layer is 330 or more by HB, the hardness of the thickness middle portion is 300 or more by HB, and the hardness difference ⁇ HB between the surface layer and the thickness middle portion is 30 or less.
  • Patent Document 1 does not aim to stably cause the hardness of the thickness middle portion to be HB 350 or more.
  • the present invention provides a steel plate in which the plate thickness exceeds 200 mm, Ceq shown by the following Formula is 0.800% or less, and Ceq is 0.750% or more for the purpose of securing the hardness of the thickness middle portion, the hardness of the surface layer and the thickness middle portion is HB 350 or more, the absorbed energy of the thickness middle portion at -20°C is 47 J or more, and a method of manufacturing the same.
  • the present invention it is possible to provide a steel plate which is excellent in hardness of a surface layer and a thickness middle portion and impact absorbed energy performance of the thickness middle portion and suppresses Ceq to 0.800% or less even in a steel plate having a plate thickness of more than 200 mm, and the steel plate is applicable to a rotating mechanism of a large industrial machine represented by a rotary kiln.
  • a thickness middle portion 11 of a steel plate 1 is a region between a plane at a depth of 3/8 of a plate thickness T of the steel plate 1 from a rolled surface 13, which is the outermost surface of the steel plate 1, and a plane at a depth of 5/8 of the plate thickness T of the steel plate 1 from the rolled surface 13.
  • the center surface of the thickness middle portion 11 of the steel plate 1 and the center surface of the steel plate 1 are coincident with each other.
  • the surface layer 12 of the steel plate 1 is a region between a plane at a depth of 1 mm and a plane at a depth of 5 mm from the rolled surface 13 of the steel plate 1.
  • the region from the outermost surface of the steel plate 1 to the depth of 1 mm is excluded from the surface layer 12 of the steel plate 1 in the present embodiment. This is because the area corresponds to a decarburized layer and a portion to be removed during processing.
  • test pieces for a mechanical test, microstructure observation, and the like are to be collected from portions separated from the end portions of the steel plate in the length direction and the width direction by the plate thickness or more.
  • the following (1) to (7) have important meanings.
  • Composition Parameter Formula (3) and a precipitation treatment (5) are particularly important.
  • the amount of C needs to satisfy 0.16% to 0.20% as a composition (mass%) of the steel.
  • the amount of C In order to secure both the toughness and the hardness at the thickness middle portion of the steel plate having a plate thickness of more than 200 mm, it is necessary to suppress the formation of carbides, which become the brittle fracture origin.
  • the amount of C In order to suppress the formation of carbides and to achieve vE- 20°C (ave.) ⁇ 47 J at the thickness middle portion, as shown in FIG. 2 , the amount of C has to be 0.20% or less.
  • a decrease in the amount of C greatly reduces the hardness of the steel. Therefore, in order to cause the hardness of the middle portion to be HB 350 or more after tempering at 500°C or more, the amount of C needs to be 0.16% or more as shown in FIG. 2 .
  • Ceq calculated by Formula (1) needs to satisfy 0.750% or more after a precipitation treatment, which will be described later, is performed. This is to avoid the formation of ferrite, which is a soft structure, during quenching and to form a structure primarily containing bainite and martensite. From the viewpoint of achieving both the hardness and toughness of the middle portion, it is not necessary to determine the upper limit of Ceq. However, an increase in Ceq tends to cause weld cracking.
  • the element symbol included in Formula (1) shows the amount (mass%) of the corresponding element in the chemical composition of the steel plate.
  • the present inventors found that in the steel plate having a plate thickness of more than 200 mm, in a case where Ceq is less than 0.750%, the hardness of the thickness middle portion becomes less than HB 350 even if the precipitation treatment is performed. It is considered that the reason way the hardness of the thickness middle portion is insufficient in the case where Ceq is less than 0.750% that ferrite which is a soft structure is formed. Ceq may be 0.755% or more, 0.760% or more, or 0.770% or more. In addition, the steel in which the hardness of the thickness middle portion is insufficient even if Ceq is 0.750% or more is plotted in FIG. 3 . The reason why the hardness of the thickness middle portion in this steel is insufficient is that the precipitation treatment is not performed.
  • the parameter f defined by Formula (2) and the parameter g defined by Formula (3) need to satisfy a relationship in which 4 ⁇ f/g is 9.00 or more.
  • f 4 ⁇ C + Si + 2 ⁇ Mn + Ni + 2 ⁇ Cr + 5 ⁇ Mo:
  • g 2 ⁇ Cr + 3 ⁇ Mo + 5 ⁇ V:
  • the element symbol included in Formula (2) and Formula (3) shows the amount (mass%) of the corresponding element in the chemical composition of the steel plate.
  • the present inventors found that in the steel plate in which the plate thickness is more than 200 mm, Ceq ⁇ 0.800% is satisfied, and the hardness of the thickness middle portion is HB 350 or more, the toughness of the thickness middle portion cannot be secured in a case where 4 ⁇ f/g is less than 9.00.
  • the element related to the parameter f is an element that improves the hardenability of the steel plate by being solutionized in the matrix during quenching.
  • the element related to the parameter g is an element that reduces the toughness of the steel plate by forming precipitates during tempering. That is, while these elements improve the hardenability, they reduce the toughness by the formation of precipitates during tempering. A large 4 ⁇ f/g indicates that the hardenability is increased while reducing the elements precipitated during tempering.
  • 4 ⁇ f/g may be 9.20 or more, 9.50 or more, or 9.80 or more.
  • the upper limit of 4 ⁇ f/g need not be particularly defined, but may be, for example, 11.00, 10.70, 10.50, 10.00, or 9.90.
  • the Al content needs to be 0.050% or more, and Al ⁇ N (the product of the Al content (mass%) and the N content (mass%) of the steel plate) needs to be 2.0 ⁇ 10 -4 or more.
  • Al ⁇ N the product of the Al content (mass%) and the N content (mass%) of the steel plate
  • the amount of Al is less than 0.050% or Al ⁇ N is less than 2.0 ⁇ 10 -4 , the prior austenite grain size is coarsened, and the low temperature toughness of the middle portion of the steel plate is deteriorated. It is considered that this is because the total amount of AlN is insufficient.
  • AlN which acts as austenite pinning particles in the steel plate according to the present is too fine to be observed. Therefore, it is industrially unpractical to define the distribution state of AlN itself acting as the austenite pinning particles. From this, it is possible to understand the usefulness of controlling AlN acting as the austenite pinning particles by the parameter Al ⁇ N.
  • Al ⁇ N may be 2.2 ⁇ 10 -4 or more, 2.5 ⁇ 10 -4 or more, or 3.0 ⁇ 10 -4 or more.
  • the upper limit of Al ⁇ N need not be particularly defined, but 5.95 ⁇ 10 -4 which is the product of the upper limits of the Al content and the N content, which will be described later, may be used as the upper limit of Al ⁇ N.
  • Al ⁇ N may be 5.7 ⁇ 10 -4 or less, 5.5 ⁇ 10 -4 or less, 5.2 ⁇ 10 -4 or less, or 4.8 ⁇ 10 -4 or less.
  • a slab is heated to the AlN solid solution temperature Ts or more calculated by Formula (4). Hot rolling is performed after the solutionizing treatment.
  • a hot rolled steel plate is heated to a precipitation treatment temperature Tp, which is a temperature of more than 550°C and less than Ac1, and is retained at the precipitation treatment temperature Tp for a precipitation treatment time tp.
  • Ts 7400 / 1.95 ⁇ log 10 Al ⁇ N ⁇ 273 :
  • Ts in Formula (4) is the solid solution temperature (°C) of AIN
  • Al and N are the Al content and the N content, respectively.
  • Tp in the Formula (5) is the precipitation treatment temperature (°C)
  • tp is the precipitation treatment time (hour).
  • the precipitation treatment temperature Tp is defined as the average temperature of the steel plate of the thickness middle portion after the temperature of the thickness middle portion of the steel plate lastly exceeds "the maximum temperature of the thickness middle portion of the steel plate during the precipitation treatment - 40°C" until the steel plate is extracted from a heat treatment furnace.
  • the precipitation treatment temperature Tp is a value calculated by Formula (8).
  • the precipitation treatment time tp is defined as the time (that is, "t B -t A ") after the temperature of the thickness middle portion of the steel plate lastly exceeds "the maximum temperature of the thickness middle portion of the steel plate during the precipitation treatment - 40°C" until the steel plate is extracted from the heat treatment furnace. If the precipitation treatment temperature Tp obtained by applying the time history of the temperature during the precipitation treatment of the thickness middle portion of the steel plate to Formula (8) described above is more than 550°C and less than Ac1, and the precipitation treatment temperature Tp and the precipitation treatment time tp satisfy Formula (5), it is determined that a suitable precipitation treatment has been performed.
  • the present inventors measured vE- 20°C of a steel plate manufactured by applying various precipitation treatment times tp and precipitation treatment temperatures Tp to a steel having composition A4 of the Examples described below. The results are shown in FIG. 5 . It can be seen from FIG. 5 that in order to obtain the austenite pinning effect of AlN, it is necessary to perform the precipitation treatment at an appropriate precipitation treatment temperature Tp for a precipitation treatment time tp.
  • FIG. 5 plots steel plates with the horizontal axis representing the precipitation treatment temperature Tp of each of the steel plates and the vertical axis representing L0g 10 (tp) of each of the steel plates.
  • the unit of tp is time (Hr).
  • the steel plates plotted by X marks are those having a vE- 20°C of less than 47 J
  • the steel plates plotted by O marks are those having a vE- 20°C of 47 J or more. It can be seen from FIG. 5 that the toughness cannot be secured under the processing condition of L0g 10 (tp) + 0.012 ⁇ T ⁇ 8.7.
  • the hardness of the thickness middle portion in order to cause the hardness of the thickness middle portion to be HB 350 or more in the composition range of the steel plate according to the present embodiment, it is necessary to perform quenching under predetermined conditions after sufficient precipitation of AlN caused by the above-mentioned precipitation treatment. Specifically, it is necessary to reheat the hot rolled steel plate to a quenching retention temperature Tq of 900°C or more and 950°C or less, retain the hot rolled steel plate at this temperature for a quenching retention time tq (minute) or more represented by Formula (6), and then performing a quenching treatment by water cooling the hot rolled steel plate.
  • Tq quenching retention temperature
  • tq 0.033 ⁇ 950 ⁇ Tq 2 + 1.5 ⁇ f 2 / 10 :
  • Tq is the quenching retention temperature (°C)
  • f is a value obtained by Formula (2) described above.
  • the quenching retention temperature Tq indicates not the setting temperature of the heat treatment furnace but the temperature of the thickness middle portion of the steel plate.
  • the quenching retention temperature Tq is defined as the average temperature of the steel plate of the thickness middle portion after the temperature of the thickness middle portion of the steel plate lastly exceeds "the maximum temperature of the thickness middle portion of the steel plate during the quenching - 40°C" until the steel plate is extracted from a heat treatment furnace.
  • the quenching retention temperature Tq is a value calculated by Formula (9).
  • the quenching retention time of the steel plate as an actual value is defined as the time (that is, "t 2 -t 1 ") after the temperature of the thickness middle portion of the steel plate lastly exceeds "the maximum temperature of the thickness middle portion of the steel plate during the quenching - 40°C" until the steel plate is extracted from the heat treatment furnace.
  • the quenching retention time of the steel plate as the actual value defined as "t 2 -t 1 " below is described as "actual tq”.
  • the quenching retention temperature Tq may be controlled based on a value measured by inserting a thermocouple into the vicinity of the thickness middle portion of the steel plate, or the like, or this value may be controlled based on an estimated value obtained by heat conduction calculation based on the furnace temperature, the plate thickness, and the like.
  • a quenching retention temperature (target Tq) and a quenching retention time (target tq) as target values that satisfy Formula (6) are determined in advance.
  • the steel plate is inserted into the heat treatment furnace, the steel plate is heated to a temperature range within a target Tq ⁇ 20°C, and retained at the temperature.
  • a cooling treatment for quenching is performed.
  • the actual Tq is calculated by applying the time history T(t) of the actual temperature (measured value or estimated value) of the thickness middle portion of the steel plate to Formula (8) described above.
  • the time elapsed from the time t 1 at which the temperature of the thickness middle portion of the steel plate lastly exceeds "the maximum temperature of the thickness middle portion of the steel plate during the quenching - 40°C" to the time t 2 at which the steel plate is extracted from the heat treatment furnace is regarded as the actual tq.
  • the necessary tq is calculated by substituting the actual Tq into Tq of Formula (6). In a case where the actual tq is not smaller than the necessary tq (that is, in a case of the actual tq ⁇ the necessary tq), it is determined that an appropriate quenching treatment has been performed.
  • FIG. 6A shows the results of an experiment using a steel having composition A6 of the Examples described later
  • FIG. 6B shows the results of an experiment using a steel having composition A2 of the Examples described later.
  • the present inventors manufactured various steel plates by applying various temperature retention times (the time for which the temperature of the middle portion of the hot rolled steel plate is retained isothermally at the quenching retention temperature Tq) and the quenching retention temperature Tq to these steels and measured the middle portion hardness thereof.
  • FIGS. 6A and 6B plot the steel plates with the horizontal axis representing the quenching retention temperature Tq of each of the steel plates and the vertical axis representing the temperature retention time of each of the steel plates.
  • the steel plates plotted by X marks are those having a middle portion hardness of less than 350 HB
  • the steel plates plotted by O marks are those having a middle portion hardness of 350 HB or more.
  • the steel plates having a temperature retention time shorter than the quenching retention time tq represented by Formula (6) described above have a middle portion hardness of less than HB 350. It is considered that this is because alloys that improve the hardenability were not sufficiently solutionized in the matrix and the hardenability could not be secured.
  • the quenching retention time tq is a function of f because the larger the amount of alloys, the longer the time necessary for such solutionizing.
  • the tempering temperature needs to be 500°C or more.
  • the tempering temperature needs to be 500°C or more in order to secure the toughness of the steel plate by sufficiently tempering the structure.
  • the hardness may be rapidly reduced due to tempering at more than 550°C. From this, the tempering temperature needs to be 550°C or less. After this tempering, the steel plate is cooled to 150°C or less.
  • the total area ratio of martensite and bainite is 99% or more.
  • the remainder of the structure is not particularly defined, for example, ferrite, pearlite, and retained austenite can be considered.
  • Other structures are acceptable in an amount of less than 1 area%
  • the above structure is achieved by quenching under conditions under which ferrite is not formed and tempering at a sufficiently high temperature. Specifically, the structure is achieved by performing quenching on the steel plate having a composition of Ceq ⁇ 0.750% under the above conditions after the precipitation treatment under the above conditions and performing tempering thereon under the above conditions.
  • Ferrite is a factor that reduces the hardness of steel.
  • ferrite tends to be formed at the thickness middle portion where the quenching cooling rate is slow.
  • the amount of ferrite has to be as low as possible.
  • pearlite Although pearlite is effective in securing hardness, it becomes a brittle fracture origin because of its hardness. Therefore, the amount of pearlite has to be as low as possible. Pearlite is formed by the concentration of C discharged during ferrite precipitation. Therefore, the formation of pearlite is simultaneously suppressed by the avoidance of ferrite precipitation.
  • Retained austenite is a brittle fracture origin and reduces the toughness of steel. Therefore, the amount of retained austenite has to be as low as possible.
  • tempering is performed at a tempering temperature of 500°C or more, the formation of retained austenite is suppressed.
  • the unit "%" of the amount of an alloying element means mass%.
  • C increases the hardness of a hardened structure and is thus an element effective for improving the hardness.
  • 0.16% is set to the lower limit of the C content.
  • an excessive amount of C impairs the toughness of the steel plate and also becomes a factor of the hardness difference between the surface layer and the middle portion. Therefore, similarly based on the experimental results shown by FIG. 2 described above, the upper limit of the C content is set to 0.20%.
  • the C content may be 0.17% or more, 0.18% or more, or 0.19% or more.
  • the C content may be 0.19% or less, 0.18% or less, or 0.17% or less.
  • Si has a deoxidizing effect. Moreover, Si is an element also effective for improving the strength of a steel plate, and can improve hardenability without raising Ceq. Therefore, the Si content is 0.50% or more. However, a large amount of Si promotes temper embrittlement and reduces the toughness of the steel plate. Therefore, it is preferable to reduce the Si content, and the upper limit thereof is 1.00%.
  • the Si content may be 0.60% or more, 0.65% or more, or 0.70% or more.
  • the Si content may be 0.90% or less, 0.85% or less, or 0.80% or less.
  • Mn has a deoxidizing effect.
  • Mn is an element which improves hardenability and is effective in improving the strength of a steel plate. Therefore, the Mn content is 0.90% or more.
  • excessive Mn promotes temper embrittlement and lowers the toughness of the steel plate. Therefore, the upper limit of the Mn content is 1.50%.
  • the Mn content may be 1.00% or more, 1.05% or more, or 1.10% or more.
  • the Mn content may be 1.40% or less, 1.35% or less, or 1.30% or less.
  • P is an impurity element contained in steel.
  • P is a harmful element that promotes intergranular embrittlement and reduces the toughness of the steel plate. Therefore, the P content is preferably as small as possible. Therefore, the P content is reduced to 0.010% or less. Since P is not required by the steel plate according to the present embodiment, the lower limit of the P content is 0%. However, from the viewpoint of refining cost and productivity, the P content may be defined as 0.001% or more. The P content may be 0.002% or more, 0.003% or more, or 0.005% or more. The P content may be 0.008% or less, 0.007% or less, or 0.006% or less.
  • S is an impurity element contained in steel.
  • S is an element that reduces the toughness of a steel plate through segregation and formation of sulfides. Therefore, it is preferable that the S content is as small as possible. Therefore, the S content is reduced to 0.0020% or less. Since S is not required by the steel plate according to the present embodiment, the lower limit of the S content is 0%. However, from the viewpoint of refining cost and productivity, the S content may be 0.0004% or more.
  • the S content may be 0.0005% or more, 0.0006% or more, or 0.0007% or more.
  • the S content may be 0.0018% or less, 0.0015% or less, or 0.0010% or less.
  • Cu is an element that can increase the strength of steel without impairing low temperature toughness.
  • the upper limit of the Cu content is 0.40%.
  • Cu contributes to suppression of ferrite by raising Ceq
  • the lower limit of the Cu content is 0%.
  • the lower limit of the Cu content may be set to 0.01% or 0.02%.
  • the Cu content may be 0.03% or more, 0.05% or more, or 0.10% or more.
  • the Cu content may be 0.35% or less, 0.30% or less, or 0.20% or less.
  • Ni is an element effective in improving the strength and toughness of steel. Therefore, the Ni content is 0.20% or more. On the other hand, the effect is saturated even if the amount of Ni is excessive, and increasing the amount of Ni, which is an expensive alloy, causes the deterioration of the manufacturing cost. Therefore, the upper limit of the Ni content is 1.00%.
  • the Ni content may be 0.25% or more, 0.30% or more, or 0.40% or more.
  • the Ni content may be 0.90% or less, 0.80% or less, or 0.70% or less.
  • Cr and Mo have a function of improving hardenability and increasing the middle portion hardness. Moreover, Cr and Mo also have an effect of raising the hardness of the surface layer and the middle portion by precipitation quenching. Therefore, the amount of each of Cr and Mo is 0.60% or more. However, there is concern that excessive amounts of Cr and Mo may lower the toughness due to the formation of alloy carbides. Therefore, the upper limit of the Cr content is 0.99%, and the upper limit of the Mo content is 1.00%.
  • the Cr content may be 0.65% or more, 0.70% or more, or 0.75% or more.
  • the Cr content may be 0.95% or less, 0.90% or less, or 0.80% or less.
  • the Mo content may be 0.65% or more, 0.70% or more, or 0.75% or more.
  • the Mo content may be 0.95% or less, 0.90% or less, or 0.80% or less.
  • V 0% to 0.050%
  • V improves the base metal strength through the formation of carbides.
  • a large amount of V causes a reduction in toughness due to the formation of alloy carbides. Therefore, the upper limit of the V content is 0.050%.
  • V contributes to suppression of ferrite by raising Ceq, since V is an expensive alloying element and can be substituted with another alloy, V is not essential for the steel plate according to the present embodiment. Therefore, the lower limit of the V content is 0%.
  • the lower limit of the V content may be 0.003%.
  • the V content may be 0.005% or more, 0.010% or more, or 0.015% or more.
  • the V content may be 0.045% or less, 0.040% or less, or 0.035% or less.
  • Al is an element effective as a deoxidizing material. Furthermore, Al is bonded to N in steel to form AIN, which contributes to the refinement of the structure. In addition, Al forms AlN in the precipitation treatment and contributes to the decomposition of BN, thereby also having a function of stabilizing the hardenability exhibited by B. Therefore, the Al content is 0.050% or more. However, an excess of Al forms coarse AlN and causes a reduction in toughness and cracking in a cast piece. Therefore, the upper limit of the Al content is 0.085%. The Al content may be 0.055% or more, 0.060% or more, or 0.065% or more. The Al content may be 0.080% or less, 0.075% or less, or 0.070% or less.
  • the lower limit of the N content is set to 0.0020%.
  • the upper limit of the N content is set to 0.0070%.
  • the N content may be 0.0025% or more, 0.0030% or more, or 0.0035% or more.
  • the N content may be 0.0065% or less, 0.0060% or less, or 0.0050% or less.
  • Al ⁇ N (the product of the Al content and the N content) needs to be 2.0 ⁇ 10 -4 or more.
  • the purpose is to utilize the austenite pinning effect of AIN, which contributes to the refinement of the structure of the steel plate.
  • B is an element which improves the hardenability of steel and improves the strength. Therefore, the B content is 0.0005% or more. However, in a case where B is excessively contained, B forms carboborides and lowers the hardenability. Therefore, the upper limit of the B content is 0.0020%.
  • the B content may be 0.0007% or more, 0.0008% or more, or 0.0010% or more.
  • the B content may be 0.0018% or less, 0.0016% or less, or 0.0015% or less.
  • the amounts of the following elements that affect the toughness are specified as selective elements.
  • the lower limit of the amount of each of the selective elements is 0%.
  • Nb 0% to 0.050%
  • Nb is an element that contributes to the refinement of the internal structure of steel by forming carbonitrides, and affects the toughness. Therefore, 0.001% or more of Nb can be contained. However, coarse carbonitrides generated by a large amount of Nb rather lower the toughness. Therefore, the upper limit of the Nb content is 0.050%.
  • the Nb content may be 0.002% or more, 0.005% or more, or 0.008% or more.
  • the Nb content may be 0.045% or less, 0.040% or less, or 0.035% or less.
  • Ti is an element that contributes to the refinement of the structure by forming stable nitrides and affects the toughness. Therefore, 0.001% or more of Ti can be contained. However, an excess of Ti causes a reduction in toughness due to coarse nitrides. Therefore, the upper limit of the Ti content is 0.020%.
  • the Ti content may be 0.002% or more, 0.005% or more, or 0.008% or more.
  • the Ti content may be 0.018% or less, 0.016% or less, or 0.012% or less.
  • Ti/N may be 3.3 or less, 3.2 or less, or 3.0 or less. Although it is not necessary to define the lower limit of Ti/N, since the lower limit of the Ti content is 0%, the lower limit of Ti/N may be defined as 0%. Ti/N may be 0.2 or more, 0.5 or more, or 1.0 or more.
  • All of Ca, Mg, and REM are bonded to harmful impurities such as S to form harmless inclusions. Accordingly, all of Ca, Mg, and REM can improve mechanical properties such as the toughness of steel. Therefore, the amount of each of Ca, Mg, and REM can be 0.0001% or more. However, when the amounts of Ca, Mg, and REM become excessive, not only is the effect saturated, but also the erosion of refractory materials such as casting nozzles is promoted. Therefore, the upper limit of the amount of each of Ca, Mg, and REM is 0.0030%. The amount of each of Ca, Mg, and REM may be 0.0002% or more, 0.0005% or more, or 0.0010% or more.
  • the amount of each of Ca, Mg, and REM may be 0.0025% or less, 0.0020% or less, or 0.0015% or less.
  • the term "REM” refers to a total of 17 elements consisting of Sc, Y, and lanthanoids, and "amount of REM” means the total amount of these 17 elements.
  • the remainder of the chemical composition of the steel plate according to the present embodiment contains iron and impurities.
  • Impurities are components which are incorporated due to various factors of the raw material such as ore or scrap, or a manufacturing process in the industrial production of steel.
  • the average value of the prior austenite grain size in the thickness middle portion of the steel plate according to the present embodiment is less than 80 ⁇ m. In a case where the prior austenite grain size in the thickness middle portion is less than 80 ⁇ m, the thickness middle portion has high toughness.
  • the prior austenite grain size of the thickness middle portion may be 76 ⁇ m or less, 73 ⁇ m or less, 70 ⁇ m or less, or 68 ⁇ m or less.
  • the refinement of the prior austenite grain size in the thickness middle portion of the steel plate according to the present embodiment is achieved mainly by the austenite pinning effect of fine AlN, as described above.
  • the plate thickness of the steel plate according to the present embodiment is more than 200 mm. Since a steel plate having a thickness of more than 200 mm can be used as a material of a huge gear used in a rotating mechanism of a large industrial machine represented by a rotary kiln, the steel plate has high industrial applicability. However, the steel plate according to the present embodiment has good hardness and low temperature toughness even when the plate thickness is 200 mm or less.
  • the thickness of the steel plate may be 205 mm or more, 210 mm or more, or 220 mm or more.
  • the upper limit of the plate thickness of the steel plate is not particularly limited, but the plate thickness may be 250 mm or less, 240 mm or less, or 230 mm or less.
  • the -20°C Charpy absorbed energy (vE- 20°C ) measured in the C direction of the thickness middle portion of the steel plate according to the present embodiment is 47 J or more.
  • the Charpy absorbed energy is a three-point average of values measured according to American Society for Testing and Materials (ASTM) A370-2017a.
  • vE- 20°C measured in the C direction is vE- 20°C obtained using a Charpy impact test piece collected along the C direction (direction perpendicular to the rolling direction and the plate thickness direction).
  • a steel plate that satisfies the above requirements with respect to Charpy absorbed energy has high low temperature toughness even in the thickness middle portion where it is usually difficult to control mechanical properties.
  • the -20°C Charpy absorbed energy measured in the C direction at the thickness middle portion of the steel plate according to the present embodiment may be 50 J or more, 55 J or more, or 60 J or more. Although it is not necessary to define the upper limit of the -20°C Charpy absorbed energy measured in the C direction at the thickness middle portion of the steel plate according to the present embodiment, for example, the upper limit may be defined as 400 J, 380 J, or 350 J.
  • the hardness of the surface layer and the thickness middle portion of the steel plate according to the present embodiment is HB 350 or more.
  • the hardness of the steel plate according to the present embodiment is a five-point average of HBW 10/3000 (indenter diameter 10 mm, test force 3000 kgf) defined in JIS Z 2243-1:2018.
  • the steel plate that satisfies the above requirements in terms of hardness does not have excessive hardness at the surface layer while having high hardness in the thickness middle portion where it is usually difficult to secure high hardness, and is thus highly applicable as steel for machine structural use.
  • the hardness of the surface layer of the steel plate according to the present embodiment may be HB 360 or more, HB 370 or more, or HB 380 or more.
  • the hardness of the thickness middle portion of the steel plate according to the present embodiment may be HB 360 or more, HB 370 or more, or HB 380 or more.
  • the upper limit of the hardness of the surface layer of the steel plate according to the present embodiment need not be defined, but may be defined as, for example, HB 450, HB 420, or HB 400.
  • the upper limit of the hardness of the thickness middle portion of the steel plate according to the present embodiment need not be defined, but may be defined as, for example, HB 450, HB 420 or HB 400.
  • the composition of the steel plate is measured according to a known method at a 1/4T portion of the steel plate (a position at a depth of 1/4 of the thickness T of the steel plate from the rolled surface of the steel plate and the vicinity thereof) in order to exclude the effects of surface layer decarburization and segregation. Based on the measured values, Ceq, Al ⁇ N, Ti/N, and 4 ⁇ f/g of the steel plate are calculated. If the molten steel analysis value of a slab which is the material of the steel plate is known, the analysis value may be regarded as the chemical composition of the steel plate.
  • the -20°C Charpy absorbed energy (vE- 20°C ) measured in the C direction of the thickness middle portion is measured according to ASTM A370-2017a.
  • Test pieces are V-notch test pieces. Three test pieces are collected from the thickness middle portion of the steel plate. During the collection of the test pieces, the longitudinal direction of the test pieces and the C direction of the steel plate (the direction perpendicular to the rolling direction and the plate thickness direction) are caused to be coincident with each other. The average value of vE- 20°C of these three test pieces is taken as the -20°C Charpy absorbed energy measured in the C direction at the thickness middle portion of the steel plate.
  • the hardness of the surface layer of the steel plate and the hardness of the thickness middle portion of the steel plate are measured based on JIS Z 2243-1:2018.
  • HBW 10/3000 is obtained by setting the indenter diameter to 10 mm and the test force to 3000 kgf.
  • the measurement of the surface layer hardness is performed by pressing an indenter against the surface formed by removing the area from the rolled surface of the steel plate to a depth of at least 1 mm.
  • the average value of the measurement results of the surface layer hardness at five points is taken the hardness of the surface layer of the steel plate.
  • the hardness of the thickness middle portion of the steel plate is measured by pressing an indenter against a portion corresponding to the thickness middle portion in a section formed by cutting the steel plate parallel to the rolled surface.
  • the average value of the measurement results of the hardness of the thickness middle portion at five points is taken as the hardness of the thickness middle portion of the steel plate.
  • a method of measuring the area ratios of martensite and bainite in the thickness middle portion is as follows.
  • An observed section is a surface parallel to the rolling direction of the steel plate, and is subjected to polishing and nital etching.
  • the observed section is observed with an optical microscope at a magnification of 500-fold. Based on the optical micrograph, the sum of the area ratios of martensite and bainite can be measured.
  • the total area of the observed visual field is 0.300 mm 2 or more.
  • a method of measuring the average value of the prior austenite particle size in the thickness middle portion is as follows.
  • An observed section is a surface parallel to the rolling direction of the steel plate, and is subjected to polishing and picric acid etching.
  • the average section length is measured by a section method, and the average section length is taken as the average prior ⁇ particle size.
  • the section length at the time of measurement is 1000 ⁇ m (1 mm) or more.
  • it is not necessary to particularly determine the upper limit of the section length it is not necessary to measure a section with a length of more than 2000 ⁇ m (2 mm), and the upper limit thereof may be 2000 ⁇ m (2 mm).
  • the steel plate according to the present embodiment can be obtained according to the manufacturing conditions described below. However, even a steel plate obtained by conditions other than the manufacturing conditions described below corresponds to the steel plate according to the present embodiment as long as the above-described requirements are satisfied.
  • the method of manufacturing the steel plate according to the present embodiment includes, as shown in FIG. 7 , a step S1 of heating a slab, a step S2 of hot rolling the slab to obtain a steel plate, a step S3 of cooling the steel plate, and a step S4 of performing a precipitation treatment on the steel plate, a step S5 of performing a quenching treatment on the steel plate, and a step S6 of tempering the steel plate.
  • the manufacturing conditions in these steps are as shown in the following table.
  • the slab is heated to a temperature equal to or more than the AlN solid solution temperature Ts calculated by Formula (4) described above.
  • the technical significance of the AlN solid solution temperature Ts is as described above.
  • the composition of the slab not only be the upper and lower limits of each of the alloying elements satisfied, but also it is necessary, as in the steel plate, Ceq is 0.750% to 0.800%, Al ⁇ N is 2.0 ⁇ 10 -4 or more, Ti/N is 3.4 or less, and 4 ⁇ f/g is 9.00 or more.
  • Preferable numerical ranges of the amount of each alloying element, Ceq, Al ⁇ N, Ti/N, and 4 ⁇ f/g are the same as those of the steel plate. In a case where the molten steel analysis value of the slab is known, that value may be regarded as the chemical composition of the slab.
  • the step S2 of hot rolling the heated slab is not particularly limited. Since the present embodiment aims to manufacture a steel plate having a thickness of more than 200 mm, the thickness of the steel plate (hot-rolled steel plate) obtained by the hot rolling is more than 200 mm.
  • step S3 of cooling the steel plate it is preferable to complete the transformation from austenite in the structure of the steel plate to other structures by cooling the steel plate to 500°C or less, and preferably 150°C or less.
  • step S4 of performing the precipitation treatment on the steel plate the steel plate is heated to the precipitation treatment temperature Tp, and the temperature is retained at this temperature T.
  • the precipitation treatment temperature Tp is a temperature of more than 550°C and less than Ac1, and is regarded as satisfying Formula (5) described above.
  • the precipitation treatment time tp is also regarded as satisfying Formula (5) described above.
  • the technical significance of the precipitation treatment conditions is as described above.
  • the steel plate may be cooled to 500°C or less, and preferably 150°C or less (for example, room temperature), or may be heated as it is for subsequent quenching.
  • the steel plate is heated to the quenching retention temperature Tq (°C) of 900°C or more and 950°C or less, is subjected to temperature retention for the quenching retention time tq (minute) or more represented by Formula (6), and is then subjected to water cooling.
  • Tq quenching retention temperature
  • tq quenching retention time
  • the technical significance of the quenching retention temperature Tq and the quenching retention time tq is as described above.
  • means for cooling the steel plate after the completion of the temperature retention is water cooling or one that can achieve a cooling rate equivalent to this.
  • the quenching finishing temperature is, for example, 150°C or less.
  • the steel plate is tempered at a tempering temperature of 500°C or more and 550°C or less and is then cooled to 150°C or less.
  • the technical significance of the tempering temperature is as described above.
  • the hardness of the surface layer of the steel plate and the hardness of the thickness middle portion of the steel plate were measured based on JIS Z 2243-1:2018.
  • HBW 10/3000 was obtained by setting the indenter diameter to 10 mm and the test force to 3000 kgf.
  • the measurement of the surface layer hardness was performed by pressing the indenter against the surface formed by removing the area from the rolled surface of the steel plate to a depth of at least 1 mm.
  • the average value of the measurement results of the surface layer hardness at five points was taken as the hardness of the surface layer of the steel plate (Table 4 "HB surface layer").
  • the hardness of the thickness middle portion of the steel plate was measured by pressing the indenter against a portion corresponding to the thickness middle portion in a surface formed by cutting the steel plate parallel to the rolled surface.
  • the average value of the measurement results of the thickness middle portion hardness at five points was taken as the hardness of the thickness middle portion of the steel plate (Table 4 "HB middle portion").
  • the test pieces of the steel plate were collected from portions separated from the end portions of the steel plate in the length direction and the width direction by the plate thickness or more.
  • the -20°C Charpy absorbed energy (vE- 20°C ) measured in the C direction of the thickness middle portion was measured according to ASTM A370-2017a. Three test pieces were collected from the thickness middle portion of the steel plate.
  • a method of measuring the area ratios of martensite and bainite in the thickness middle portion is as follows. An observed section was a surface parallel to the rolling direction of the steel plate, and was subjected to polishing and nital etching. The observed section is observed with an optical microscope at a magnification of 500-fold. Based on the optical micrograph, the sum of the area ratios of martensite and bainite was measured. The total area of the observed visual field was 0.300 mm 2 or more.
  • a method of measuring the average value of the prior-austenite particle size in the thickness middle portion was as follows. An observed section was a surface parallel to the rolling direction of the steel plate, and was subjected to polishing and picric acid etching. The average section length was measured by a section method (section length: 1000 ⁇ m or more and 2000 ⁇ m or less), and the average section length was taken as the average value of the prior austenite grain size of the thickness middle portion (Table 4 "prior ⁇ grain size").
  • compositions are shown in Tables 2-1 and 2-2, manufacturing methods are shown in Tables 3-1 to 3-3, and materials, evaluation and the like are shown in Table 4.
  • the "precipitation treatment temperature Tp" described in the tables is a value obtained by applying the thermal history at the time of the precipitation treatment to Formula (8).
  • the "precipitation treatment time tp” described in the tables is the time after the temperature of the thickness middle portion of the steel plate lastly exceeds "the maximum temperature of the thickness middle portion of the steel plate during the precipitation treatment - 40°C" until the steel plate is extracted from the heat treatment furnace.
  • the “quenching retention temperature Tq” described in the tables is a value obtained by applying the thermal history at the time of the quenching treatment to Formula (9).
  • the "actual quenching retention time” described in the tables means is the time after the temperature of the thickness middle portion of the steel plate lastly exceeds "the maximum temperature of the thickness middle portion of the steel plate during the quenching - 40°C" until the steel plate is extracted from the heat treatment furnace (that is, actual tq).
  • the "quenching retention time tq” described in the tables is a value obtained by substituting the quenching retention temperature Tq and f described in the tables into the Formula (6) described above.
  • 2.2E-04 means 2.2 ⁇ 10 -4 .
  • Precipitation treatment time threshold 10 ⁇ 0.012 ⁇ Tp + 8.7 : [Table 2-1] Composition C Si Mn Cu Ni Cr Mo V Al N B P S Nb Ti Ca Mg REM A1 0.19 0.54 1.02 0.32 0.94 0.74 0.86 0.003 0.060 0.0036 0.0007 0.0082 0.0004 A2 0.18 0.95 1.39 0.02 0.40 0.90 0.89 0.004 0.072 0.0034 0.0015 0.0027 0.0020 0.0025 A3 0.16 0.73 1.30 0.06 0.82 0.89 0.90 0.025 0.081 0.0041 0.0006 0.0091 0.0019 0.010 A4 0.18 0.51 1.42 0.10 0.61 0.76 0.77 0.038 0.056 0.0055 0.0019 0.0092 0.0014 0.0018 0.0011 A5 0.18 0.89 1.41 0.40 0.30 0.74 0.75 0.015 0.084 0.0050 0.0014 0.0035 0.0016 0.0022 A6 0.19 0.85 0.96 0.26 0.85 0.95 0.73 0.0
  • Test Nos. 1 to 10 satisfy the chemical composition range of the present invention and suitable manufacturing conditions.
  • the total area ratio of martensite and bainite is 99% or more in all the steels, the average value of the prior austenite grain size in the middle portion is 80 ⁇ m or less, and the surface layer hardness, the middle portion hardness, the middle portion impact absorbed energy satisfy the targets.
  • Test Nos. 11 and 12 C deviates from the chemical composition range of the present invention.
  • C is insufficient, and the hardness at the time of quenching is insufficient, so that the hardness cannot satisfy the target value even after tempering.
  • Test No. 12 is an example in which C is excessive, and the impact absorbed energy is low due to the influence of precipitation of hard carbides which are fracture origins.
  • Test Nos. 13 and 14 Si deviates from the chemical composition range of the present invention.
  • Si is insufficient, and the hardenability cannot be secured, so that the middle portion hardness cannot satisfy the target value.
  • Test No. 14 is an example in which Si is excessive, and although the hardness is sufficient, the impact absorbed energy does not satisfy the target due to the promotion of temper embrittlement by Si.
  • Test Nos. 15 and 16 Mn deviates from the chemical composition range of the present invention.
  • Mn is insufficient, and the hardness at the time of quenching is insufficient, so that the middle portion hardness cannot satisfy the target value even after tempering.
  • Test No. 16 is an example in which Mn is excessive, and the impact absorbed energy does not satisfy the target value due to the promotion of temper embrittlement.
  • the P content is high outside the chemical composition range of the present invention, and although the hardness is sufficient, the impact absorbed energy does not satisfy the target due to the embrittlement caused by P.
  • the Ni content is low outside the chemical composition range of the present invention, and does not satisfy the amount that improves the toughness. Therefore, in Test No. 20, the impact absorbed energy does not satisfy the target.
  • Test Nos. 21 and 22 are examples in which Cr deviates from the chemical composition range of the present invention.
  • Cr is insufficient, and sufficient hardenability and precipitation strengthening action are not obtained. From this, in the test No. 21, the middle portion hardness does not satisfy the target, and furthermore, the impact absorbed energy does not achieve the target.
  • Cr was excessive, and the influence of precipitation of coarse Cr carbides was significant. As a result, in Test No. 22, the impact absorbed energy does not satisfy the target.
  • Test Nos. 23 and 24 are examples in which Mo deviates from the chemical composition range of the present invention.
  • Mo is insufficient, and sufficient hardenability and precipitation strengthening action are not obtained. From this, in Test No. 23, the middle portion hardness does not satisfy the target, and the impact absorbed energy does not achieve the target.
  • Mo was excessive, and the influence of precipitation of coarse Mo carbides was significant. Accordingly, in Test No. 24, the impact absorbed energy does not satisfy the target value.
  • V was high outside the chemical composition range of the present invention, and coarse carbides and nitrides of V and the like became the brittle fracture origin. From this, in Test No. 25, the impact absorbed energy does not satisfy the target.
  • Test Nos. 26 and 27 are examples in which Al deviates from the chemical composition range of the present invention.
  • Test No. 26 is an example in which Al is insufficient, AlN effective for austenite pinning could not be secured, and an excess of N was bonded B, so that the effect of improving the hardenability was reduced. For this reason, in Test No. 26, the structures other than martensite and bainite were excessive, and the grain size of retained austenite was coarsened. As a result, in Test No. 26, the middle portion hardness and the impact absorbed energy cannot satisfy the targets.
  • Test No. 27 is an example in which Al is excessive, and AlN was excessively coarsened and became a brittle fracture origin. Therefore, in Test No. 27, the impact absorbed energy cannot satisfy the target.
  • Test Nos. 28 and 29 are examples in which N deviates from the chemical composition range of the present invention.
  • Test No. 28 is an example in which N is insufficient and Al ⁇ N is less than a predetermined range, and the amount of nitrides, carbonitrides, and the like formed was insufficient, so that the austenite pinning effect was weak and grain coarsening had occurred.
  • Test No. 29 is an example in which N is excessive, and excessive coarsening of nitrides, carbonitrides, and the like occurs. As a result, in Test No. 29, the impact absorbed energy cannot satisfy the target.
  • Test Nos. 30 and 31 B deviates from the chemical composition range of the present invention.
  • Test No. 30 is an example in which B was insufficient, and the amount of solute B necessary for hardenability could not be secured.
  • Test No. 30 the structures other than martensite and bainite are excessive, and the middle portion hardness and impact absorbed energy cannot satisfy the targets.
  • Test No. 31 is an example in which B is excessively contained, and carboborides of metal elements are precipitated, so that the impact absorbed energy cannot satisfy the target.
  • Test No. 32 although the composition range of each alloying element is within the range of the present invention, Ceq is low outside the suitable scope of the present invention. In Test No. 32, as a result of the formation of ferrite in the structure due to the decrease in hardenability, the middle portion hardness and impact absorbed energy cannot satisfy the targets.
  • Test No. 35 although various indexes derived from the composition range of each alloying element and the chemical composition are within the ranges of the present invention, the heating temperature before rolling is less than the solid solution temperature Ts. In Test No. 35, undissolved coarse AlN remained and became a brittle fracture origin. Therefore, in Test No. 35, the prior austenite grain size is coarsened, and the absorbed energy cannot satisfy the target.
  • Test Nos. 36 and 37 although various indexes derived from the composition range of each alloying element and the chemical composition are within the ranges of the present invention, the precipitation treatment temperature deviates from the suitable range of the present invention.
  • Test No. 36 is an example in which the precipitation treatment temperature was low, and AlN was not sufficiently precipitated, so that AIN effective for austenite pinning could not be secured. From this, in Test No. 36, the prior austenite grain size is coarsened, and the absorbed energy cannot satisfy the target.
  • Test No. 37 is an example in which the precipitation treatment temperature exceeded Ac1, and the coarsening of AlN had occurred locally due to the retention in the ⁇ - ⁇ dual region. Therefore, in Test No. 37, the absorbed energy cannot satisfy the target.
  • Test No. 38 is an example in which, although various indexes derived from the composition range of each alloying element and the chemical composition were within the ranges of the present invention, the temperature and time of the precipitation treatment did not satisfy Formula (5), which is a suitable range of the present invention.
  • Formula (5) which is a suitable range of the present invention.
  • AIN was not sufficiently precipitated, so that AlN effective for austenite pinning could not be secured. From this, in Test No. 38, the prior austenite grain size is coarsened, and the absorbed energy cannot satisfy the target.
  • Test No. 39 is an example in which, although various indexes derived from the composition range of each alloying element and the chemical composition are within the ranges of the present invention, the quenching temperature is less than the suitable range of the present invention.
  • solutionizing of the alloying elements was not sufficiently performed, so that the hardenability was low and ferrite was excessively formed. Accordingly, in Test No. 39, the middle portion hardness and the absorbed energy cannot satisfy the targets.
  • Test No. 40 is an example in which, although various indexes derived from the composition range of each alloying element and the chemical composition are within the ranges of the present invention, the quenching retention temperature Tq exceeds the suitable range of the present invention. Test No. 40 resulted in excessive coarsening of grains. From this, in Test No. 40, the prior austenite grain size is coarsened, and the absorbed energy cannot satisfy the target.
  • Test No. 41 is an example in which, although various indexes derived from the composition range of each alloying element and the chemical composition are within the ranges of the present invention, the actual quenching retention time is less than the quenching retention time tq, which is the suitable range of the present invention, and solutionizing of the alloying elements was not sufficiently performed. From this, in Test No. 41, the hardenability was low and ferrite was excessively formed. As a result, in Test No. 41, the middle portion hardness and the absorbed energy cannot satisfy the targets.
  • Test No. 42 is an example in which, although various indexes derived from the composition range of each alloying element and the chemical composition are within the ranges of the present invention, the tempering temperature is less than the suitable range. In Test No. 42, temper embrittlement had occurred. From this, in Test No. 42, the absorbed energy cannot satisfy the target.
  • Test No. 43 is an example in which, although various indexes derived from the composition range of each alloying element and the chemical composition are within the ranges of the present invention, the tempering temperature is more than the suitable range. In Test No. 43, the precipitation quenching effect of the alloy carbides was reduced. Therefore, in Test No. 43, the middle portion hardness does not satisfy the target.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Claims (3)

  1. Plaque d'acier comprenant, en tant que composition chimique, en % en masse :
    C : 0,16 % à 0,20 % ;
    Si : 0,50 % à 1,00 % ;
    Mn : 0,90 % à 1,50 % ;
    P : 0,010 % ou moins ;
    S : 0,0020 % ou moins ;
    Cu : 0 % à 0,40 % ;
    Ni : 0,20 % à 1,00 % ;
    Cr : 0,60 % à 0,99 % ;
    Mo : 0,60 % à 1,00 % ;
    V : 0 % à 0,050 % ;
    Al : 0,050 % à 0,085 % ;
    N : 0,0020 % à 0,0070 % ;
    B : 0,0005 % à 0,0020 % ;
    Nb : 0 % à 0,050 % ;
    Ti : 0 % à 0,020 % ;
    Ca : 0 % à 0,0030 % ;
    Mg : 0 % à 0,0030 % ;
    REM : 0 % à 0,0030 % ; et
    un reste comprenant du Fe et des impuretés,
    dans laquelle un rapport de surface totale de martensite et de baïnite dans une partie médiane de l'épaisseur est de 99 % ou plus, la partie médiane étant la région comprise entre un plan à une profondeur de 3/8 d'une épaisseur de plaque de la plaque d'acier à partir d'une surface laminée, qui est la surface la plus externe de la plaque d'acier, et un plan à une profondeur de 5/8 de l'épaisseur de plaque de la plaque d'acier à partir de la surface laminée,
    une valeur moyenne de taille de grain d'austénite antérieur dans la partie médiane de l'épaisseur est inférieure à 80 µm,
    Ceq représenté par la formule (1) est de 0,750 % à 0,800 %,
    Al × N est 2,0 × 10-4 ou plus,
    Ti/N est 3,4 ou moins,
    une valeur f représentée par la formule (2) et une valeur g représentée par la formule (3) satisfont à 4 × f/g ≥ 9,00,
    une énergie absorbée Charpy à -20°C mesurée dans une direction C dans la partie médiane de l'épaisseur, qui est déterminée conformément à la description, est de 47 J ou plus,
    les duretés d'une couche de surface et de la partie médiane de l'épaisseur, qui sont déterminées conformément à la description, sont de HB 350 ou plus, et
    une épaisseur de plaque de la plaque d'acier est supérieure à 200 mm, Ceq = C + Mn / 6 + Cu + Ni / 15 + Cr + Mo + V / 5 :
    Figure imgb0031
     f = 4 × C + Si + 2 × Mn + Ni + 2 × Cr + 5 × Mo:
    Figure imgb0032
     g = 2 × Cr + 3 × Mo + 5 × V:
    Figure imgb0033
    où chaque symbole d'élément décrit dans chacune des formules désigne une quantité d'un élément correspondant au symbole d'élément en % d'unité de masse.
  2. Procédé de fabrication de la plaque d'acier selon la revendication 1, ladite méthode comprenant :
    le chauffage d'une brame ;
    le laminage à chaud de la brame pour obtenir une plaque d'acier ayant une épaisseur de plaque supérieure à 200 mm ;
    le refroidissement de la plaque d'acier ;
    la réalisation d'un traitement par précipitation sur la plaque d'acier ;
    la recuisson de la plaque d'acier ; et
    la trempe de la plaque d'acier,
    où la brame comprend, en tant que composition chimique, en % d'unité de masse, C : 0,16 % à 0,20 %, Si : 0,50 % à 1,00 %, Mn : 0,90 % à 1,50 %, P : 0,010 % ou moins, S : 0,0020 % ou moins, Cu : 0 % à 0,40 %, Ni : 0,20 % à 1,00 %, Cr : 0,60 % à 0,99 %, Mo : 0,60 % à 1,00 %, V : 0 % à 0,050 %, Al : 0,050 % à 0,085 %, N : 0,0020 % à 0,0070 %, B : 0,0005 % à 0,0020 %, Nb : 0 % à 0,050 %, Ti : 0 % à 0,020 %, Ca : 0 % à 0,0030 %, Mg : 0 % à 0,0030 %, REM : 0 % à 0,0030 %, et un restant comprenant du Fe et des impuretés, Ceq représenté par la formule (1) de la brame va de 0,750 % à 0,800 %, Al × N de la brame est 2,0 × 10-4 ou plus, Ti/N de la brame est 3,4 ou moins, et une valeur f de la brame représentée par la formule (2) et une valeur g de la brame représentée par la formule (3) satisfont à 4 × f/g ≥ 9,00,
    une température de chauffage de brame lors du chauffage de la brame est égale ou supérieure à une température en solution solide d'AlN Ts (°C) calculée selon la formule (4),
    le traitement par précipitation est réalisé sur la plaque d'acier en chauffant la plaque d'acier à une température de traitement par précipitation Tp (°C) supérieure à 550°C et inférieure à Ac1 et en maintenant la plaque d'acier à cette température pendant un temps de traitement par précipitation tp (heure), la température de traitement par précipitation Tp (°C) et le temps de traitement par précipitation tp (heure) répondent à la formule (5), et Ac1 est représenté par la formule (7),
    la recuisson est réalisée sur la plaque d'acier en chauffant la plaque d'acier à une température de maintien de recuisson Tq (°C) de 900°C à 950°C, en maintenant la plaque d'acier à ladite température pendant un temps de maintien de recuisson tq (minute) ou plus, représenté par la formule (6), et refroidissement à l'eau de la plaque d'acier, et
    la trempe est réalisée sur la plaque d'acier en chauffant la plaque d'acier à une température de trempe de 500°C à 550°C et en refroidissant la plaque d'acier à 150°C ou moins, Ceq = C + Mn / 6 + Cu + Ni / 15 + Cr + Mo + V / 5 :
    Figure imgb0034
     f = 4 × C + Si + 2 × Mn + Ni + 2 × Cr + 5 × Mo:
    Figure imgb0035
     g = 2 × Cr + 3 × Mo + 5 × V:
    Figure imgb0036
     Ts = 7400 / 1,95 − log 10 Al × N − 273 :
    Figure imgb0037
     Log 10 tp + 0,012 × Tp ≥ 8,7 :
    Figure imgb0038
     tq = 0,033 × 950 − Tq 2 + 1,5 × f 2 / 10 :
    Figure imgb0039
     Ac 1 = 750 − 25 × C + 22 × Si − 40 × Mn − 30 × Ni + 20 × Cr + 25 × Mo:
    Figure imgb0040
    où chaque symbole d'élément décrit dans chacune des formules désigne une quantité d'un élément correspondant au symbole d'élément en % d'unité de masse.
  3. Procédé de fabrication de la plaque d'acier selon la revendication 2, dans laquelle une température de refroidissement de finition lors du refroidissement de la plaque d'acier est de 150°C ou moins.
EP18922100.5A 2018-08-20 2018-08-20 Plaque d'acier et son procédé de fabrication Active EP3633060B1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2018/030676 WO2020039485A1 (fr) 2018-08-20 2018-08-20 Tôle d'acier et son procédé de production

Publications (3)

Publication Number Publication Date
EP3633060A1 EP3633060A1 (fr) 2020-04-08
EP3633060A4 EP3633060A4 (fr) 2020-05-06
EP3633060B1 true EP3633060B1 (fr) 2021-12-29

Family

ID=65999146

Family Applications (1)

Application Number Title Priority Date Filing Date
EP18922100.5A Active EP3633060B1 (fr) 2018-08-20 2018-08-20 Plaque d'acier et son procédé de fabrication

Country Status (6)

Country Link
EP (1) EP3633060B1 (fr)
JP (1) JP6493645B1 (fr)
KR (1) KR102115277B1 (fr)
CN (1) CN111083928B (fr)
AU (1) AU2018430608B2 (fr)
WO (1) WO2020039485A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110129720A (zh) * 2019-04-28 2019-08-16 徐州箱桥机械有限公司 一种变速箱齿轮在稀土渗碳设备上的热处理方法
CN114645182B (zh) * 2022-03-23 2022-10-14 承德建龙特殊钢有限公司 一种齿轮钢及其制备方法与应用

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01279709A (ja) * 1988-05-06 1989-11-10 Kobe Steel Ltd 直接焼入れによるプラスチック金型用プレハードン鋼の製造方法
JP4897125B2 (ja) * 2010-05-14 2012-03-14 新日本製鐵株式会社 高強度鋼板とその製造方法
JP5136609B2 (ja) * 2010-07-29 2013-02-06 Ｊｆｅスチール株式会社 成形性および耐衝撃性に優れた高強度溶融亜鉛めっき鋼板およびその製造方法
JP5804229B1 (ja) * 2014-01-28 2015-11-04 Ｊｆｅスチール株式会社 耐摩耗鋼板およびその製造方法
JP6398576B2 (ja) * 2014-10-10 2018-10-03 新日鐵住金株式会社 靭性に優れた鋼板およびその製造方法
JP5979338B1 (ja) * 2014-11-18 2016-08-24 Ｊｆｅスチール株式会社 材質均一性に優れた厚肉高靭性高張力鋼板およびその製造方法
AU2016322190B2 (en) * 2015-09-17 2019-05-23 Jfe Steel Corporation Steel structure for hydrogen gas with excellent hydrogen embrittlement resistance in high pressure hydrogen gas and method of producing the same
JP6762868B2 (ja) * 2016-03-31 2020-09-30 株式会社神戸製鋼所 高強度鋼板およびその製造方法
JP6733269B2 (ja) 2016-04-04 2020-07-29 日本製鉄株式会社 表層と板厚中心部の硬度に優れ、かつ表層と中心の硬度差の小さい板厚２００ｍｍ超の厚鋼板およびその製造方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Also Published As

Publication number Publication date
AU2018430608A1 (en) 2020-03-05
AU2018430608B2 (en) 2021-02-04
CN111083928A (zh) 2020-04-28
KR20200022387A (ko) 2020-03-03
JPWO2020039485A1 (ja) 2020-08-27
CN111083928B (zh) 2020-11-20
EP3633060A1 (fr) 2020-04-08
EP3633060A4 (fr) 2020-05-06
WO2020039485A1 (fr) 2020-02-27
JP6493645B1 (ja) 2019-04-03
KR102115277B1 (ko) 2020-05-26

Similar Documents

Publication Publication Date Title
EP2980250B1 (fr) Plaque d'acier résistant à l'abrasion ayant une excellente ténacité à basse température et son procédé de fabrication
EP2942415B1 (fr) Tôle d'acier résistant à l'abrasion qui présente une excellente ténacité à basse température ainsi qu'une certaine résistance à la fragilisation par l'hydrogène, et procédé de fabrication de cette dernière
KR102130949B1 (ko) 내마모 강판 및 내마모 강판의 제조 방법
TWI404808B (zh) 淬火性優異之硼添加鋼板及製造方法
KR102122193B1 (ko) 내마모 강판 및 내마모 강판의 제조 방법
KR20180125540A (ko) 내마모 강판 및 내마모 강판의 제조 방법
KR20180125541A (ko) 내마모 강판 및 내마모 강판의 제조 방법
KR20090098909A (ko) 내지연 파괴 특성이 우수한 고장력 강재 그리고 그 제조 방법
KR20170118879A (ko) 산세성 및 담금질 템퍼링 후의 내지연파괴성이 우수한 볼트용 선재, 및 볼트
CN108315637B (zh) 高碳热轧钢板及其制造方法
WO2006022053A1 (fr) PRODUIT EN ACIER À HAUTE RÉSISTANCE, EXCELLENT EN TERMES DE SOUDABILITÉ ET DE TÉNACITÉ ET AYANT UNE RÉSISTANCE À LA TRACTION DE CLASSE 550 MPa OU PLUS, ET PROCÉDÉ DE PRODUCTION CORRESPONDANT
JP7211530B2 (ja) 耐摩耗鋼板および耐摩耗鋼板の製造方法
KR20130108403A (ko) 열간 단조용 압연 봉강 또는 선재
JP7226598B2 (ja) 耐摩耗鋼板およびその製造方法
JPH11335777A (ja) 冷間加工性と低浸炭歪み特性に優れた肌焼鋼とその製造方法
JP6798557B2 (ja) 鋼
EP3633060B1 (fr) Plaque d'acier et son procédé de fabrication
JP5489497B2 (ja) 焼入性に優れたボロン鋼鋼板の製造方法
WO2022153790A1 (fr) Matériau en acier inoxydable à base de martensite et son procédé de production
JP2001279383A (ja) 高温浸炭特性に優れた高温浸炭用鋼ならびに高温浸炭用熱間鍛造部材
EP3467130B1 (fr) Plaque d'acier à haute résistance à la traction présentant une excellente ténacité à basse température
JP7063420B1 (ja) 耐摩耗鋼板および耐摩耗鋼板の製造方法
JP7063419B1 (ja) 耐摩耗鋼板および耐摩耗鋼板の製造方法
WO2021240740A1 (fr) Fil d'acier à ressort, ressort et procédé de production associé
EP4363628A1 (fr) Acier super-bainitique, objet comprenant ledit acier et procédé de fabrication dudit objet

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: UNKNOWN

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20191219

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

A4 Supplementary search report drawn up and despatched

Effective date: 20200406

RIC1 Information provided on ipc code assigned before grant

Ipc: C21D 1/18 20060101ALI20200331BHEP

Ipc: C22C 38/04 20060101ALI20200331BHEP

Ipc: C21D 1/02 20060101ALI20200331BHEP

Ipc: C22C 38/40 20060101ALI20200331BHEP

Ipc: C21D 8/02 20060101ALI20200331BHEP

Ipc: C22C 38/02 20060101ALI20200331BHEP

Ipc: C22C 38/00 20060101AFI20200331BHEP

Ipc: C22C 38/18 20060101ALI20200331BHEP

Ipc: C22C 38/54 20060101ALI20200331BHEP

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

RIC1 Information provided on ipc code assigned before grant

Ipc: C22C 38/02 20060101ALI20201123BHEP

Ipc: C22C 38/54 20060101ALI20201123BHEP

Ipc: C22C 38/44 20060101ALI20201123BHEP

Ipc: C22C 38/18 20060101ALN20201123BHEP

Ipc: C21D 8/02 20060101ALI20201123BHEP

Ipc: C22C 38/46 20060101ALN20201123BHEP

Ipc: C22C 38/00 20060101ALI20201123BHEP

Ipc: C22C 38/22 20060101ALN20201123BHEP

Ipc: C22C 38/04 20060101ALI20201123BHEP

Ipc: C22C 38/50 20060101ALN20201123BHEP

Ipc: C21D 1/18 20060101ALI20201123BHEP

Ipc: C21D 1/02 20060101AFI20201123BHEP

Ipc: C22C 38/40 20060101ALN20201123BHEP

Ipc: C22C 38/06 20060101ALI20201123BHEP

RIC1 Information provided on ipc code assigned before grant

Ipc: C22C 38/00 20060101ALI20201203BHEP

Ipc: C22C 38/22 20060101ALN20201203BHEP

Ipc: C21D 1/02 20060101AFI20201203BHEP

Ipc: C22C 38/46 20060101ALN20201203BHEP

Ipc: C22C 38/44 20060101ALI20201203BHEP

Ipc: C22C 38/50 20060101ALN20201203BHEP

Ipc: C21D 8/02 20060101ALI20201203BHEP

Ipc: C22C 38/02 20060101ALI20201203BHEP

Ipc: C22C 38/06 20060101ALI20201203BHEP

Ipc: C22C 38/54 20060101ALI20201203BHEP

Ipc: C22C 38/18 20060101ALN20201203BHEP

Ipc: C22C 38/40 20060101ALN20201203BHEP

Ipc: C22C 38/04 20060101ALI20201203BHEP

Ipc: C21D 1/18 20060101ALI20201203BHEP

RIC1 Information provided on ipc code assigned before grant

Ipc: C22C 38/04 20060101ALI20201209BHEP

Ipc: C22C 38/50 20060101ALN20201209BHEP

Ipc: C21D 1/02 20060101AFI20201209BHEP

Ipc: C21D 1/18 20060101ALI20201209BHEP

Ipc: C22C 38/40 20060101ALN20201209BHEP

Ipc: C22C 38/54 20060101ALI20201209BHEP

Ipc: C22C 38/02 20060101ALI20201209BHEP

Ipc: C22C 38/06 20060101ALI20201209BHEP

Ipc: C22C 38/44 20060101ALI20201209BHEP

Ipc: C22C 38/18 20060101ALN20201209BHEP

Ipc: C21D 8/02 20060101ALI20201209BHEP

Ipc: C22C 38/46 20060101ALN20201209BHEP

Ipc: C22C 38/22 20060101ALN20201209BHEP

Ipc: C22C 38/00 20060101ALI20201209BHEP

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
INTG Intention to grant announced

Effective date: 20201221

GRAJ Information related to disapproval of communication of intention to grant by the applicant or resumption of examination proceedings by the epo deleted

Free format text: ORIGINAL CODE: EPIDOSDIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

INTC Intention to grant announced (deleted)
REG Reference to a national code

Ref country code: DE

Ref legal event code: R079

Ref document number: 602018028984

Country of ref document: DE

Free format text: PREVIOUS MAIN CLASS: C22C0038000000

Ipc: C21D0001020000

RIC1 Information provided on ipc code assigned before grant

Ipc: C21D 1/02 20060101AFI20210420BHEP

Ipc: C21D 1/18 20060101ALI20210420BHEP

Ipc: C22C 38/02 20060101ALI20210420BHEP

Ipc: C22C 38/04 20060101ALI20210420BHEP

Ipc: C22C 38/06 20060101ALI20210420BHEP

Ipc: C21D 8/02 20060101ALI20210420BHEP

Ipc: C22C 38/00 20060101ALI20210420BHEP

Ipc: C22C 38/44 20060101ALI20210420BHEP

Ipc: C22C 38/54 20060101ALI20210420BHEP

Ipc: C22C 38/18 20060101ALN20210420BHEP

Ipc: C22C 38/22 20060101ALN20210420BHEP

Ipc: C22C 38/40 20060101ALN20210420BHEP

Ipc: C22C 38/46 20060101ALN20210420BHEP

Ipc: C22C 38/50 20060101ALN20210420BHEP

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

RIC1 Information provided on ipc code assigned before grant

Ipc: C21D 1/02 20060101AFI20210520BHEP

Ipc: C21D 1/18 20060101ALI20210520BHEP

Ipc: C22C 38/02 20060101ALI20210520BHEP

Ipc: C22C 38/04 20060101ALI20210520BHEP

Ipc: C22C 38/06 20060101ALI20210520BHEP

Ipc: C21D 8/02 20060101ALI20210520BHEP

Ipc: C22C 38/00 20060101ALI20210520BHEP

Ipc: C22C 38/44 20060101ALI20210520BHEP

Ipc: C22C 38/54 20060101ALI20210520BHEP

Ipc: C22C 38/18 20060101ALN20210520BHEP

Ipc: C22C 38/22 20060101ALN20210520BHEP

Ipc: C22C 38/40 20060101ALN20210520BHEP

Ipc: C22C 38/46 20060101ALN20210520BHEP

Ipc: C22C 38/50 20060101ALN20210520BHEP

INTG Intention to grant announced

Effective date: 20210601

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE PATENT HAS BEEN GRANTED

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 602018028984

Country of ref document: DE

REG Reference to a national code

Ref country code: AT

Ref legal event code: REF

Ref document number: 1458702

Country of ref document: AT

Kind code of ref document: T

Effective date: 20220115

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: LT

Ref legal event code: MG9D

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: RS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: LT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: BG

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20220329

REG Reference to a national code

Ref country code: NL

Ref legal event code: MP

Effective date: 20211229

REG Reference to a national code

Ref country code: AT

Ref legal event code: MK05

Ref document number: 1458702

Country of ref document: AT

Kind code of ref document: T

Effective date: 20211229

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: NO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20220329

Ref country code: LV

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: HR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20220330

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SM

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: SK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: RO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: PT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20220429

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: EE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: CZ

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: PL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: AT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20220429

REG Reference to a national code

Ref country code: DE

Ref legal event code: R097

Ref document number: 602018028984

Country of ref document: DE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

Ref country code: AL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20220930

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MC

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20220820

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20220831

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20220831

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20220820

REG Reference to a national code

Ref country code: BE

Ref legal event code: MM

Effective date: 20220831

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20220820

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20220831

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20220820

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20230627

Year of fee payment: 6

Ref country code: FR

Payment date: 20230703

Year of fee payment: 6

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: HU

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT; INVALID AB INITIO

Effective date: 20180820

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: CY

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20211229