WO2024063113A1 - Steel base material - Google Patents

Steel base material Download PDF

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Publication number
WO2024063113A1
WO2024063113A1 PCT/JP2023/034188 JP2023034188W WO2024063113A1 WO 2024063113 A1 WO2024063113 A1 WO 2024063113A1 JP 2023034188 W JP2023034188 W JP 2023034188W WO 2024063113 A1 WO2024063113 A1 WO 2024063113A1
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Prior art keywords
steel
base material
steel base
fire
yield strength
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PCT/JP2023/034188
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French (fr)
Japanese (ja)
Inventor
俊夫 村上
安英 岡
貴之 山本
美枝 橘
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株式会社神戸製鋼所
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Publication of WO2024063113A1 publication Critical patent/WO2024063113A1/en

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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
    • 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
    • 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
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon

Definitions

  • the present invention relates to steel base materials used in buildings.
  • Steel base materials are widely used in buildings, mainly as base materials for indoor ceilings and walls. Since steel base materials are used for general purposes, JIS A 6517:2010 specifies their properties such as shape, material, and strength as members. In this JIS standard, as the material for the steel base material, JIS G 3302:2019 “hot-dip galvanized steel sheets and steel strips” or JIS G 3321:2019 “hot-dip 55% aluminum-zinc alloy coated steel sheets and steel strips” are specified. It is stipulated that those that meet the requirements should be used.
  • the Building Standards Act stipulates the fire resistance required for each part of a building, such as non-damaging properties, heat shielding properties, and flame blocking properties.
  • a fire-resistant coating is attached to the steel base material to ensure fireproofing properties such as heat insulation and flame resistance.
  • a wall structure includes columns made of steel base material arranged at regular intervals and fireproof covering materials such as plasterboard attached to these columns.
  • the fire-resistant coating will protect the steel base material by blocking heat and flames, and ultimately protect the building. However, if the fire-resistant coating is damaged, such as cracked, the fire-resistant performance of the fire-resistant construction, such as its heat-insulating and flame-blocking properties, will be lost.
  • Patent Document 1 discloses a technique for preventing damage to the fireproof coating in a fireproof structure using such a steel base material and fireproof coating. Specifically, Patent Document 1 describes a steel frame column, a fireproof covering material in which plate-like bodies arranged to surround the steel frame column are connected to each other at corners to form a cylindrical body, and the fireproof coating material. a spacer disposed between the steel column and the fireproof coating to separate the fireproof coating and the steel column; the spacer contacts both the steel column and the fireproof coating, and the spacer contacts only one of them.
  • the steel frame is fixed to a steel frame, the steel frame column and the fireproof covering material are movable relative to each other in the axial direction of the steel frame column, and the steel frame is configured such that the steel column and the fireproof covering material do not follow a change in the length of both materials due to heating.
  • a dry fireproof construction of the column is disclosed.
  • Patent document 1 describes that the spacer is fixed to either the steel column or the fire-resistant covering material, and that the steel column and the fire-resistant covering material are capable of moving relative to each other in the axial direction of the steel column. This means that even if the steel column expands thermally, no stress is applied to the fire-resistant covering material, and there is no risk of damage caused by the thermal expansion of the steel column.
  • Patent Document 1 requires the introduction of spacers between the steel base material and the fire-resistant coating material, which requires leaving space for the spacers, thereby narrowing the living space of the building.
  • Non-Patent Document 1 describes that lightweight steel frames are used as base materials in partition wall specifications (non-load-bearing walls).
  • Non-Patent Document 2 describes that steel wall base materials are non-structural. For these reasons, it is believed that in the past, it was not necessary to guarantee non-damage related to the collapse of buildings in terms of fire resistance, and it was assumed that there would be no problem in terms of performance even if the strength was reduced during a fire. For this reason, the use of fire-resistant galvanized steel sheets with excellent high-temperature properties (e.g., Patent Document 2) as building steel base materials has not been considered in the past.
  • an object of the present invention is to provide a steel base material that is less likely to buckle at high temperatures.
  • a steel base material according to one aspect of the present invention includes a steel plate having a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C.
  • FIG. 1 is a graph showing the relationship between yield strength and temperature.
  • FIG. 2 is a graph showing the relationship between the heating time determined by FEM and the amount of strain in the length direction of the heating surface.
  • the present inventors have discovered that the steel base material and the fire-resistant cladding material can be used in the fire-resistant structure of buildings equipped with the steel base material and the fire-resistant cladding material. We have discovered that it is possible to ensure fire resistance performance without introducing a spacer between the two and even if the fire-resistant coating used is thin. Therefore, according to the present invention, it is possible to provide a steel base material that is less likely to buckle at high temperatures.
  • the steel base material of this embodiment has a steel plate with a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C.
  • architectural steel base materials are generally not used for load-bearing walls that are responsible for the structure of buildings, including wall structures and ceiling structures, but are applied only to non-load-bearing walls. Therefore, in the past, no consideration has been given to applying steel plates that can maintain strength even at high temperatures to building steel base materials.
  • the present inventors have developed a fire-resistant structure for a building equipped with a steel base material and a fire-resistant coating by using a steel plate that has sufficient high-temperature strength and is resistant to buckling at high temperatures as a steel base material. found that it is possible to ensure fireproof performance even if the fireproof coating used is thin.
  • the fire-resistant coating material used in the fire-resistant structure is the same as that used in fire-resistant structures that use conventional steel plates for the steel base material, so the time from the outbreak of a fire to the occurrence of buckling in the steel base material can be delayed compared to when conventional steel plates are used, improving fire resistance.
  • the fireproof coating used for the fireproof structure is made thinner or less than when a conventional steel plate is used for the steel base material.
  • the time from the outbreak of a fire to the occurrence of buckling in the steel base material can be made the same as when conventional steel plates are used.
  • fireproof performance equivalent to that of conventional systems can be ensured, thereby making it possible to reduce costs, reduce carbon emissions, and secure a larger living space.
  • the steel plate used for the steel base material according to this embodiment has a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C.
  • a steel plate having such a configuration as a steel base material it is possible to provide a steel base material that does not easily buckle at high temperatures.
  • the yield strength at 500°C is preferably 280 MPa or more, more preferably 300 MPa or more. Although the upper limit of the yield strength at 500° C. is not particularly determined, it is preferably 500 MPa or less as a realizable value.
  • the yield strength at 600°C is preferably 150 MPa or more, more preferably 175 MPa or more. Although the upper limit of the yield strength at 600° C. is not particularly determined, it is preferably 300 MPa or less as a realizable value.
  • the yield strength at room temperature of the steel plate used for the steel base material according to the present embodiment is preferably 250 MPa or more, and more preferably 300 MPa or more. In this embodiment, room temperature is 20°C. Although there is no particular upper limit to the yield strength at room temperature, it is preferably 1000 MPa or less as a realizable value.
  • the yield strength of the steel plate according to this embodiment is a value measured by a measuring method specified in JIS G 0567:2020.
  • the steel base material according to the present embodiment may include a steel plate as described above and metal plating formed on the surface of the steel plate.
  • metal plating can be formed on the surface of a steel sheet from the perspective of increasing corrosion resistance, but the yield strength of the steel sheet as described above at 500°C, 600°C, and room temperature does not change depending on the presence or absence of plating.
  • the plated steel sheet in which metal plating is formed on the surface of the steel sheet in this embodiment preferably has a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C. The yield strength at 500° C.
  • the yield strength of the plated steel sheet at 600°C is more preferably 150 MPa or more, still more preferably 175 MPa or more, and preferably 300 MPa or less.
  • the yield strength at room temperature is preferably 250 MPa or more, more preferably 300 MPa or more, and preferably 500 MPa or less.
  • the elements contained in the steel plate include C (carbon), Si (silicon), Mn (manganese), Cu (copper), Ni (nickel), Examples include Cr (chromium), Mo (molybdenum), Ti (titanium), Nb (niobium), V (vanadium), P (phosphorus), S (sulfur), N (nitrogen), and B (boron).
  • Examples of the metal plating formed on the surface of the steel plate in the steel base material according to the present embodiment include hot-dip galvanizing, alloyed hot-dip galvanizing, hot-dip 55% aluminum-zinc alloy plating, and hot-dip zinc-aluminum-magnesium alloy. Examples include plating.
  • the structure of the steel plate of the steel base material according to the present embodiment is not particularly limited, it is preferable that the area ratio of the recrystallized structure is less than 20%.
  • the area ratio of the recrystallized structure is less than 20%, the yield strength at high temperatures can be increased more reliably. More preferably, the area ratio of the recrystallized structure is less than 10%.
  • the lower limit of the area ratio of the recrystallized structure is not particularly limited, and the smaller the area ratio is, the more reliably the yield strength at high temperatures can be increased.
  • the area ratio of the recrystallized structure can be determined using a photograph of a steel plate portion in a cross section of a steel base material taken using an optical microscope.
  • the method for manufacturing the steel base material is performed by a general method for manufacturing cold-rolled steel sheets and a hot-dip galvanizing method. An example of a method for manufacturing a steel base material will be described below.
  • steel with a desired chemical composition is cast, the cast steel is hot rolled, pickled, and cold rolled, and then transferred to a continuous annealing line (CAL or CAPL) or a continuous hot-dip galvanizing line. (CGL) or the like, it is possible to obtain a steel plate having a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C.
  • CAL or CAPL continuous annealing line
  • CGL continuous hot-dip galvanizing line
  • the conditions for heat treatment of the cold rolled steel sheet are not particularly limited as they can be changed as appropriate depending on the chemical composition of the steel and the conditions of the cold rolling. It is preferable to heat to the annealing temperature and hold at the annealing temperature for 1 to 1800 seconds. By this annealing treatment, the area ratio of the recrystallized structure can be made less than 20% in the structure of the steel sheet.
  • the annealing temperature is preferably 680°C or higher, and preferably 880°C or lower.
  • the holding time at the annealing temperature is preferably 5 s or more, and preferably 1500 s or less.
  • the steel plate after the annealing treatment is preferably cooled to 600 to 400°C at a cooling rate of 3 to 100°C/s.
  • the steel base material according to one aspect of the present invention includes a steel plate having a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C.
  • the steel plate in the steel base material having the above structure may have a yield strength of 250 MPa or more at room temperature.
  • the steel base material having the above structure may further have metal plating formed on the surface of the steel plate.
  • Steel plates A and B which will be explained below, were used as samples.
  • Steel plate A is a comparative example, and is a commercially available hot-dip galvanized steel plate (SGCC) specified in JIS G 3302:2019, to which Nb (niobium), Ti (titanium), and V (vanadium) are not added. It is.
  • the steel plate B has a component composition of C (carbon): 0.06% by mass, Si (silicon): 0.02% by mass, Mn (manganese): 1.45% by mass, and Nb (niobium) 0.
  • the cold-rolled steel sheet contains 0.02% by mass, Ti (titanium): 0.04% by mass, and the remainder is Fe (iron) and unavoidable impurities, and was manufactured in a laboratory under the following manufacturing conditions, and meets the requirements of this embodiment.
  • Ti titanium
  • Fe iron
  • Manufacturing conditions - Hot rolling conditions, cold rolling conditions The slab was heated at 1200°C, rolled to 3.6 mm, inserted into a holding furnace at 550°C to simulate winding, held for 30 minutes, and then cooled in the furnace.
  • the front and back surfaces of the cooled hot-rolled steel plate were ground to 1.6 mm. This is a laboratory process to simulate 1.6 mm hot-rolled steel sheets in actual manufacturing equipment. Thereafter, the 1.6 mm hot rolled steel plate was cold rolled to 0.8 mm.
  • the cold rolled steel plate was held at 700°C for 60 seconds, cooled to 200°C or less at a cooling rate of 10°C/s, and then allowed to cool to obtain steel plate B.
  • Steel plate B was not coated in order to verify the ideal state of a galvanized steel plate in a laboratory.
  • the area ratio of the recrystallized structure of the manufactured steel sheet B was 0.5%.
  • the area ratio of the recrystallized structure of the steel sheet A was 100%.
  • the area ratio of the recrystallized structure was determined using a photograph of the steel plate taken using an optical microscope.
  • JIS 13B tensile test pieces specified in JIS Z 2241:2022 were taken from steel plates A and B, and tensile tests were conducted at various temperatures from 20°C to 750°C in accordance with JIS G 0567:2020 to determine the yield strength. was measured. At temperatures of 100° C. or higher, tensile tests were conducted after holding each temperature for 10 minutes. The tensile speed in the tensile tester was set at 0.004 min -1 up to yield strength.
  • FIG. 1 is a graph showing the relationship between yield strength and temperature.
  • the yield strength of steel plate A at 20°C is 159 MPa, the yield strength at 500°C is 123 MPa, and the yield strength at 600°C is 101 MPa.
  • the yield strength of steel plate B at 20°C is 901 MPa, the yield strength at 500°C is 382 MPa, and the yield strength at 600°C is 167 MPa. From FIG. 1, it can be seen that steel plate B has higher yield strength at each temperature than steel plate A, and is particularly excellent in yield strength at high temperatures of 500°C and 600°C.
  • FEM finite element analysis
  • FEM was also performed on a perfectly elastic body with no yield strength.
  • FIG. 2 is a graph showing the relationship between the heating time (seconds) and the amount of strain in the length direction of the heating surface, as determined by the FEM described above.
  • steel plate A of the comparative example started plastic deformation (buckling) about 600 seconds after the start of heating.
  • steel plate B of the present invention example started plastic deformation approximately 1800 seconds after the start of heating. From these facts, it can be seen that steel plate B has superior fire resistance performance compared to steel plate A. Note that from FIG. 2 it can be seen that no plastic deformation occurs in the perfectly elastic body of the reference example.

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Abstract

One aspect of the present invention relates to a steel base material including a steel plate that has a yield strength of 250 MPa or more at 500ºC and a yield strength of 125 MPa or more at 600ºC.

Description

鋼製下地材Steel base material
　本発明は、建築物に使用される鋼製下地材に関する。 The present invention relates to steel base materials used in buildings.
　建築物において、主に屋内の天井や壁の下地材として、鋼製下地材が広く用いられている。鋼製下地材は、汎用的に使用されるため、ＪＩＳ　Ａ　６５１７：２０１０に形状、材料および部材としての強度等の特性が規定されている。このＪＩＳ規格では、鋼製下地材の材料として、ＪＩＳ　Ｇ　３３０２：２０１９の「溶融亜鉛めっき鋼板及び鋼帯」またはＪＩＳ　Ｇ　３３２１：２０１９の「溶融５５％アルミニウム－亜鉛合金めっき鋼板及び鋼帯」を満たすものを使用することが規定されている。 Steel base materials are widely used in buildings, mainly as base materials for indoor ceilings and walls. Since steel base materials are used for general purposes, JIS A 6517:2010 specifies their properties such as shape, material, and strength as members. In this JIS standard, as the material for the steel base material, JIS G 3302:2019 "hot-dip galvanized steel sheets and steel strips" or JIS G 3321:2019 "hot-dip 55% aluminum-zinc alloy coated steel sheets and steel strips" are specified. It is stipulated that those that meet the requirements should be used.
　また、建築物については、火災発生時において被害の拡大を防止するために建築基準法によって、部位ごとに必要な耐火性能、例えば非損傷性、遮熱性、遮炎性が定められている。 Additionally, in order to prevent the spread of damage in the event of a fire, the Building Standards Act stipulates the fire resistance required for each part of a building, such as non-damaging properties, heat shielding properties, and flame blocking properties.
　建築用鋼製下地材を用いた間仕切り壁や外壁、天井では、耐火性能のうち、遮熱性、遮炎性を担保するため、鋼製下地材に耐火被覆材を取り付け、耐火構造としている。例えば、壁構造では、一定間隔で配置した鋼製下地材で作製された柱と、これらの柱に貼り付けられた石膏ボードなどの耐火被覆材とを備えるものとしている。 For partition walls, exterior walls, and ceilings that use architectural steel base materials, a fire-resistant coating is attached to the steel base material to ensure fireproofing properties such as heat insulation and flame resistance. For example, a wall structure includes columns made of steel base material arranged at regular intervals and fireproof covering materials such as plasterboard attached to these columns.
　このような耐火構造を有する建築物で火災が発生した場合、耐火被覆材が熱や炎を遮ることで鋼製下地材を保護し、ひいては建築物を保護する。しかしながら、火災によって耐火被覆材が割れるなど損傷した場合には、遮熱性や遮炎性といった耐火構造の耐火性能が失われる。 If a fire breaks out in a building with such fire-resistant construction, the fire-resistant coating will protect the steel base material by blocking heat and flames, and ultimately protect the building. However, if the fire-resistant coating is damaged, such as cracked, the fire-resistant performance of the fire-resistant construction, such as its heat-insulating and flame-blocking properties, will be lost.
　そこで、建築用鋼製下地材を用いた壁構造の耐火性能を評価した際に、耐火被覆材が割れる要因について検討した結果、次のように考えられることが明らかになってきた。火災発生初期には耐火構造において熱が耐火被覆材により遮られるため、建築用鋼製下地材は常温に保たれる。しかし、火災発生から時間が経過するに従って徐々に耐火被覆材から鋼製下地材に熱が伝導し、鋼製下地材が加熱され、熱膨張が生じる。建築物において鋼製下地材は両端が他の部材に拘束されているため、この熱膨張によって他の部材から鋼製下地材が座屈により変形し、鋼製下地材に貼り付けられた耐火被覆材に応力が加わって割れが生じると考えられる。 Therefore, when evaluating the fire-resistance performance of wall structures using architectural steel base materials, we investigated the factors that cause the fire-resistance coating to crack, and as a result, we found the following possible causes. In the early stages of a fire, the heat is blocked by the fireproof sheathing in the fireproof structure, so the steel base material for construction is kept at room temperature. However, as time passes after a fire occurs, heat is gradually conducted from the fireproof coating to the steel base material, heating the steel base material and causing thermal expansion. In buildings, both ends of the steel base material are restrained by other members, so this thermal expansion causes the steel base material to buckle and deform from the other members, causing the fireproof coating attached to the steel base material to deform. It is thought that cracks occur due to stress being applied to the material.
　このような鋼製下地材および耐火被覆材を用いた耐火構造において耐火被覆材の損傷を防ぐ技術が特許文献１に開示されている。具体的に特許文献１には、鉄骨柱と、該鉄骨柱を囲むように配置された板状体が角部で互いに連結されて筒状体となった耐火被覆材と、該耐火被覆材と前記鉄骨柱との間に配置され前記耐火被覆材と前記鉄骨柱とを離隔するスペーサとを備え、該スペーサは、前記鉄骨柱と前記耐火被覆材の両者に接触すると共に両者のいずれか一方のみに固定され、前記鉄骨柱と前記耐火被覆材が前記鉄骨柱の軸方向に相対移動可能であり、加熱による両者の材長変化に該両者が追従しないようになっていることを特徴とする鉄骨柱の乾式耐火構造が開示されている。 Patent Document 1 discloses a technique for preventing damage to the fireproof coating in a fireproof structure using such a steel base material and fireproof coating. Specifically, Patent Document 1 describes a steel frame column, a fireproof covering material in which plate-like bodies arranged to surround the steel frame column are connected to each other at corners to form a cylindrical body, and the fireproof coating material. a spacer disposed between the steel column and the fireproof coating to separate the fireproof coating and the steel column; the spacer contacts both the steel column and the fireproof coating, and the spacer contacts only one of them. The steel frame is fixed to a steel frame, the steel frame column and the fireproof covering material are movable relative to each other in the axial direction of the steel frame column, and the steel frame is configured such that the steel column and the fireproof covering material do not follow a change in the length of both materials due to heating. A dry fireproof construction of the column is disclosed.
　特許文献１には、該スペーサは、前記鉄骨柱又は前記耐火被覆材のいずれか一方のみに固定され、前記鉄骨柱と前記耐火被覆材が前記鉄骨柱の軸方向に相対移動可能になっていることにより、鉄骨柱が熱膨張した場合にも、耐火被覆材には応力が作用することがなく、鉄骨柱の熱膨張に起因する損傷の危険がないことが記載されている。 Patent document 1 describes that the spacer is fixed to either the steel column or the fire-resistant covering material, and that the steel column and the fire-resistant covering material are capable of moving relative to each other in the axial direction of the steel column. This means that even if the steel column expands thermally, no stress is applied to the fire-resistant covering material, and there is no risk of damage caused by the thermal expansion of the steel column.
　一方で、特許文献１に記載の技術では、鋼製下地材と耐火被覆材との間にスペーサを導入しているため、スペーサ分の空間を設ける必要があり、建築物の居住空間を狭めることとなる。 On the other hand, the technology described in Patent Document 1 requires the introduction of spacers between the steel base material and the fire-resistant coating material, which requires leaving space for the spacers, thereby narrowing the living space of the building.
　また、鋼製下地材および耐火被覆材を備えた耐火構造については、コストの低減という経済的観点、および近年注目されている炭素排出量の削減という環境的観点から、使用する素材の量の低減が要求されている。そのため、耐火構造の防火・耐火性能を、より薄い断熱材で確保することができれば、経済的にも環境的にも有利であると考えられる。 Furthermore, for fire-resistant structures that have steel base materials and fire-resistant coating materials, there is a demand to reduce the amount of materials used from the economic perspective of reducing costs, and from the environmental perspective of reducing carbon emissions, which has been attracting attention in recent years. Therefore, if the fire prevention and fire resistance performance of fire-resistant structures can be ensured with thinner insulation materials, it is considered to be advantageous both economically and environmentally.
　さらに、上述したように、耐火被覆材が損傷する要因としては、高温において鋼製下地材が変型し、鋼製下地材に貼り付けられた耐火被覆材に応力が加わって割れが生じることだと考えられるが、鋼製下地材についてＪＩＳ　Ａ　６５１７：２０１０では高温における特性は規定されていない。つまり、当該ＪＩＳ規格を満たしているだけでは、鋼製下地材の変型を抑制することはできない。ここで、建築用鋼製下地材は、一般に、壁構造、天井構造ともに建築物の構造を担う耐力壁には用いられず、非耐力壁にのみ適用される。例えば、非特許文献１には、間仕切壁の仕様（非耐力壁）における下地として軽量鉄骨が用いられることが記載されている。また、非特許文献２には、鋼製壁下地材が非構造体であることが記載されている。このような理由により、従来は、耐火性能において、建物の倒壊に関わる非損傷性を担保する必要がなく、火災時に強度が低下しても性能面で問題がないと想定されていたと考えられる。そのため、建材用途で、高温特性に優れた耐火用亜鉛めっき鋼板（例えば、特許文献２など）を建築用鋼製下地材へ適用することは、従来検討されていなかった。 Furthermore, as mentioned above, it is believed that the cause of damage to fireproof coating materials is that the steel base material deforms at high temperatures, and stress is applied to the fireproof coating material attached to the steel base material, causing cracks. However, JIS A 6517:2010 does not specify the characteristics of steel base materials at high temperatures. In other words, simply meeting the JIS standard does not prevent the deformation of the steel base material. Here, architectural steel base materials are generally not used for load-bearing walls that support the structure of buildings, both in wall structures and ceiling structures, but are only applied to non-load-bearing walls. For example, Non-Patent Document 1 describes that lightweight steel frames are used as base materials in partition wall specifications (non-load-bearing walls). In addition, Non-Patent Document 2 describes that steel wall base materials are non-structural. For these reasons, it is believed that in the past, it was not necessary to guarantee non-damage related to the collapse of buildings in terms of fire resistance, and it was assumed that there would be no problem in terms of performance even if the strength was reduced during a fire. For this reason, the use of fire-resistant galvanized steel sheets with excellent high-temperature properties (e.g., Patent Document 2) as building steel base materials has not been considered in the past.
　そこで、本発明は、高温において座屈を生じにくい鋼製下地材を提供することを目的とする。 Therefore, an object of the present invention is to provide a steel base material that is less likely to buckle at high temperatures.
特許第６９７０３８１号公報Patent No. 6970381 特許第３２６７３２４号公報Patent No. 3267324
　本発明の一局面に係る鋼製下地材は、５００℃における降伏強度が２５０ＭＰａ以上、かつ、６００℃における降伏強度が１２５ＭＰａ以上である鋼板を有する。 A steel base material according to one aspect of the present invention includes a steel plate having a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C.
図１は、降伏強度と温度との関係を示すグラフである。FIG. 1 is a graph showing the relationship between yield strength and temperature. 図２は、ＦＥＭによって求めた加熱時間と加熱面の長さ方向の歪み量との関係を示すグラフである。FIG. 2 is a graph showing the relationship between the heating time determined by FEM and the amount of strain in the length direction of the heating surface.
　本発明者らは、鋼製下地材として高温において座屈を生じにくいものを使用することにより、鋼製下地材および耐火被覆材を備える建築物の耐火構造において、鋼製下地材と耐火被覆材との間にスペーサを導入することなく、かつ使用する耐火被覆材が薄くても耐火性能を確保することが可能であることを知見した。そのため、本発明によれば、高温において座屈を生じにくい鋼製下地材を提供することができる。 By using a steel base material that is resistant to buckling at high temperatures, the present inventors have discovered that the steel base material and the fire-resistant cladding material can be used in the fire-resistant structure of buildings equipped with the steel base material and the fire-resistant cladding material. We have discovered that it is possible to ensure fire resistance performance without introducing a spacer between the two and even if the fire-resistant coating used is thin. Therefore, according to the present invention, it is possible to provide a steel base material that is less likely to buckle at high temperatures.
　以下、本発明の一実施形態に係る鋼製下地材について説明する。 Hereinafter, a steel base material according to an embodiment of the present invention will be described.
　本実施形態に係る鋼製下地材は、５００℃における降伏強度が２５０ＭＰａ以上、かつ、６００℃における降伏強度が１２５ＭＰａ以上である鋼板を有する。 The steel base material of this embodiment has a steel plate with a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C.
　このような構成によれば、高温において座屈を生じにくい鋼製下地材を提供することができる。 According to such a configuration, it is possible to provide a steel base material that does not easily buckle at high temperatures.
　上述したように、建築用鋼製下地材は、一般に、壁構造、天井構造ともに建築物の構造を担う耐力壁には用いられず、非耐力壁にのみ適用される。そのため、従来は、建材用途において、高温でも強度を確保できる鋼板を建築用鋼製下地材へ適用することは検討されていなかった。本発明者らは、十分な高温強度を有し、高温での座屈を生じにくい鋼板を、鋼製下地材として使用することにより、鋼製下地材および耐火被覆材を備える建築物の耐火構造において、使用する耐火被覆材が薄くても耐火性能を確保することが可能であることを見出した。さらには、高温でも鋼製下地材の座屈に起因する耐火被覆材の割れを抑制できることから、鋼製下地材と耐火被覆材との間にスペーサを導入する必要がないため、建築物の居住空間をより広くできるという利点があることも明らかにした。 As mentioned above, architectural steel base materials are generally not used for load-bearing walls that are responsible for the structure of buildings, including wall structures and ceiling structures, but are applied only to non-load-bearing walls. Therefore, in the past, no consideration has been given to applying steel plates that can maintain strength even at high temperatures to building steel base materials. The present inventors have developed a fire-resistant structure for a building equipped with a steel base material and a fire-resistant coating by using a steel plate that has sufficient high-temperature strength and is resistant to buckling at high temperatures as a steel base material. found that it is possible to ensure fireproof performance even if the fireproof coating used is thin. Furthermore, cracking of the fire-resistant sheathing material caused by buckling of the steel base material can be suppressed even at high temperatures, so there is no need to introduce a spacer between the steel base material and the fire-resistant sheathing material, making it possible to prevent buildings from becoming occupied. It was also revealed that it has the advantage of making the space more spacious.
　その理由については以下のように考える。建築物で火災が発生した場合において、耐火構造を構成する鋼製下地材が加熱されると熱膨張が生じる。このとき、建築物において鋼製下地材は他の部材に両端部が拘束されているため、熱膨張により他の部材から鋼製下地材に圧縮力が作用する。火災の発生から時間が経過して、鋼製下地材に作用する圧縮力が降伏強度を超えると、鋼製下地材が座屈により変形する。この鋼製下地材の変形により、鋼製下地材に貼り付けられた耐火被覆材に応力が加わって割れが生じると、耐火構造の耐火性能が失われる。ここで、本実施形態に係る鋼板は、従来の鋼板に比べて５００℃および６００℃という高温における降伏強度が高いため、加熱されても座屈が生じにくい。そのため、建築物の耐火構造において、本実施形態に係る鋼製下地材と耐火被覆材との間にスペーサを導入しなくても、耐火被覆材の割れ等の損傷の発生を火災発生後長時間にわたって抑制することができる。これにより、耐火性能を確保しつつ建築物の居住空間をより広く確保することができる。 I think the reason is as follows. When a fire occurs in a building, thermal expansion occurs when the steel base material that makes up the fireproof structure is heated. At this time, since both ends of the steel base material are restrained by other members in the building, compressive force is applied from the other members to the steel base material due to thermal expansion. When the compressive force acting on the steel base material exceeds its yield strength after a period of time has elapsed since the fire broke out, the steel base material deforms due to buckling. When this deformation of the steel base material causes stress to be applied to the fireproof covering material attached to the steel base material and cracks occur, the fireproof performance of the fireproof structure is lost. Here, since the steel plate according to the present embodiment has a higher yield strength at high temperatures of 500° C. and 600° C. than conventional steel plates, buckling is less likely to occur even when heated. Therefore, in the fire-resistant structure of a building, even without introducing a spacer between the steel base material and the fire-resistant sheathing material according to this embodiment, damage such as cracks in the fire-resistant sheathing material can be prevented for a long time after a fire occurs. can be suppressed over a period of time. Thereby, it is possible to secure a wider living space in the building while ensuring fire resistance performance.
　また、本実施形態に係る鋼製下地材によれば、耐火構造に使用する耐火被覆材を、鋼製下地材に従来の鋼板を使用した耐火構造と同じものを使用することで、火災の発生から鋼製下地材における座屈の発生までの時間を従来の鋼板を使用した場合よりも遅らせることができ、耐火性能を向上させることができる。 In addition, with the steel base material according to this embodiment, the fire-resistant coating material used in the fire-resistant structure is the same as that used in fire-resistant structures that use conventional steel plates for the steel base material, so the time from the outbreak of a fire to the occurrence of buckling in the steel base material can be delayed compared to when conventional steel plates are used, improving fire resistance.
　さらに、本実施形態に係る鋼製下地材によれば、耐火構造に使用する耐火被覆材を、鋼製下地材に従来の鋼板を使用した場合よりも薄くしたり、少なくしたりしても、火災の発生から鋼製下地材における座屈の発生までの時間を従来の鋼板を使用した場合と同等とすることができる。すなわち耐火被覆材が少なくても従来と同等の耐火性能を確保することができ、これにより、コストの低減、炭素排出量の削減、およびより広い居住空間の確保を実現することができる。 Furthermore, according to the steel base material according to this embodiment, even if the fireproof coating used for the fireproof structure is made thinner or less than when a conventional steel plate is used for the steel base material, The time from the outbreak of a fire to the occurrence of buckling in the steel base material can be made the same as when conventional steel plates are used. In other words, even with less fireproof coating material, fireproof performance equivalent to that of conventional systems can be ensured, thereby making it possible to reduce costs, reduce carbon emissions, and secure a larger living space.
　〈鋼板〉
　本実施形態に係る鋼製下地材に用いられる鋼板は、５００℃における降伏強度が２５０ＭＰａ以上、かつ、６００℃における降伏強度が１２５ＭＰａ以上である。このような構成の鋼板を鋼製下地材として用いることによって、高温において座屈を生じにくい鋼製下地材を提供することができる。 <Steel plate>
The steel plate used for the steel base material according to this embodiment has a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C. By using a steel plate having such a configuration as a steel base material, it is possible to provide a steel base material that does not easily buckle at high temperatures.
　５００℃における降伏強度は、好ましくは２８０ＭＰａ以上であり、より好ましくは３００ＭＰａ以上である。５００℃における降伏強度の上限は特に定めないが、実現可能な数値として、好ましくは５００ＭＰａ以下である。 The yield strength at 500°C is preferably 280 MPa or more, more preferably 300 MPa or more. Although the upper limit of the yield strength at 500° C. is not particularly determined, it is preferably 500 MPa or less as a realizable value.
　６００℃における降伏強度は、好ましくは１５０ＭＰａ以上であり、より好ましくは１７５ＭＰａ以上である。６００℃における降伏強度の上限は特に定めないが、実現可能な数値として、好ましくは３００ＭＰａ以下である。 The yield strength at 600°C is preferably 150 MPa or more, more preferably 175 MPa or more. Although the upper limit of the yield strength at 600° C. is not particularly determined, it is preferably 300 MPa or less as a realizable value.
　また、本実施形態に係る鋼製下地材に用いられる鋼板の室温での降伏強度は、好ましくは２５０ＭＰａ以上であり、より好ましくは３００ＭＰａ以上である。本実施形態において、室温とは２０℃である。室温における降伏強度の上限は特に定めないが、実現可能な数値として、好ましくは１０００ＭＰａ以下である。 Further, the yield strength at room temperature of the steel plate used for the steel base material according to the present embodiment is preferably 250 MPa or more, and more preferably 300 MPa or more. In this embodiment, room temperature is 20°C. Although there is no particular upper limit to the yield strength at room temperature, it is preferably 1000 MPa or less as a realizable value.
　本実施形態に係る鋼板の降伏強度は、ＪＩＳ　Ｇ　０５６７：２０２０に規定される測定方法によって測定された値である。 The yield strength of the steel plate according to this embodiment is a value measured by a measuring method specified in JIS G 0567:2020.
　また、本実施形態に係る鋼製下地材は、上述したような鋼板と、その鋼板の表面に形成された金属めっきを有してもよい。なお、一般的に耐食性を上げるといった観点から、鋼板の表面に金属めっきを形成することができるが、上述したような鋼板の５００℃、６００℃、室温における降伏強度はめっきの有無によっては変わらない。つまり、本実施形態における鋼板の表面に金属めっきが形成されためっき鋼板は、５００℃における降伏強度が２５０ＭＰａ以上、かつ、６００℃における降伏強度が１２５ＭＰａ以上であることが好ましい。めっき鋼板の５００℃における降伏強度は、より好ましくは２８０ＭＰａ以上であり、さらに好ましくは３００ＭＰａ以上であり、５００ＭＰａ以下が好ましい。また、めっき鋼板の６００℃における降伏強度は、より好ましくは１５０ＭＰａ以上であり、さらに好ましくは１７５ＭＰａ以上であり、３００ＭＰａ以下が好ましい。室温での降伏強度は、好ましくは２５０ＭＰａ以上であり、より好ましくは３００ＭＰａ以上であり、５００ＭＰａ以下が好ましい。 Further, the steel base material according to the present embodiment may include a steel plate as described above and metal plating formed on the surface of the steel plate. Generally, metal plating can be formed on the surface of a steel sheet from the perspective of increasing corrosion resistance, but the yield strength of the steel sheet as described above at 500°C, 600°C, and room temperature does not change depending on the presence or absence of plating. . That is, the plated steel sheet in which metal plating is formed on the surface of the steel sheet in this embodiment preferably has a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C. The yield strength at 500° C. of the plated steel sheet is more preferably 280 MPa or more, still more preferably 300 MPa or more, and preferably 500 MPa or less. Further, the yield strength of the plated steel sheet at 600°C is more preferably 150 MPa or more, still more preferably 175 MPa or more, and preferably 300 MPa or less. The yield strength at room temperature is preferably 250 MPa or more, more preferably 300 MPa or more, and preferably 500 MPa or less.
　本実施形態に係る鋼板の化学組成は、特に定めないが、前記鋼板に含まれる元素としては、Ｃ（炭素）、Ｓｉ（ケイ素）、Ｍｎ（マンガン）、Ｃｕ（銅）、Ｎｉ（ニッケル）、Ｃｒ（クロム）、Ｍｏ（モリブデン）、Ｔｉ（チタン）、Ｎｂ（ニオブ）、Ｖ（バナジウム）、Ｐ（リン）、Ｓ（硫黄）、Ｎ（窒素）、Ｂ（ボロン）等が挙げられる。 Although the chemical composition of the steel plate according to this embodiment is not particularly defined, the elements contained in the steel plate include C (carbon), Si (silicon), Mn (manganese), Cu (copper), Ni (nickel), Examples include Cr (chromium), Mo (molybdenum), Ti (titanium), Nb (niobium), V (vanadium), P (phosphorus), S (sulfur), N (nitrogen), and B (boron).
　〈金属めっき〉
　本実施形態に係る鋼製下地材において鋼板の表面に形成される金属めっきとしては、例えば、溶融亜鉛めっき、合金化溶融亜鉛めっき、溶融５５％アルミニウム－亜鉛合金めっき、溶融亜鉛－アルミニウム－マグネシウム合金めっき等が挙げられる。 <Metal plating>
Examples of the metal plating formed on the surface of the steel plate in the steel base material according to the present embodiment include hot-dip galvanizing, alloyed hot-dip galvanizing, hot-dip 55% aluminum-zinc alloy plating, and hot-dip zinc-aluminum-magnesium alloy. Examples include plating.
　〈組織〉
　本実施形態に係る鋼製下地材の鋼板の組織は、特に限定されないが、再結晶組織の面積率が２０％未満であることが好ましい。再結晶組織の面積率が２０％未満であることにより、高温における降伏強度をより確実に高めることができる。再結晶組織の面積率は１０％未満であることがより好ましい。また、再結晶組織の面積率の下限値は特に限定されず、面積率が小さいほど、高温における降伏強度をより確実に高めることができる。再結晶組織の面積率は、光学顕微鏡を用いて撮影した鋼製下地材の断面における鋼板部分の写真を使用して求めることができる。 <Organization>
Although the structure of the steel plate of the steel base material according to the present embodiment is not particularly limited, it is preferable that the area ratio of the recrystallized structure is less than 20%. When the area ratio of the recrystallized structure is less than 20%, the yield strength at high temperatures can be increased more reliably. More preferably, the area ratio of the recrystallized structure is less than 10%. Further, the lower limit of the area ratio of the recrystallized structure is not particularly limited, and the smaller the area ratio is, the more reliably the yield strength at high temperatures can be increased. The area ratio of the recrystallized structure can be determined using a photograph of a steel plate portion in a cross section of a steel base material taken using an optical microscope.
　〈製造方法〉
　鋼製下地材の製造方法は、一般的な冷延鋼板の製造方法および溶融亜鉛めっき方法により行われる。鋼製下地材の製造方法の一例について以下に説明する。 <Production method>
The method for manufacturing the steel base material is performed by a general method for manufacturing cold-rolled steel sheets and a hot-dip galvanizing method. An example of a method for manufacturing a steel base material will be described below.
　例えば、まず、所望の化学組成を有する鋼を鋳造し、鋳造した鋼を熱間圧延し、酸洗、冷間圧延を施した後、連続焼鈍ライン（ＣＡＬまたはＣＡＰＬ）、または連続溶融亜鉛めっきライン（ＣＧＬ）等のプロセスで熱処理を施し、５００℃における降伏強度が２５０ＭＰａ以上、かつ、６００℃における降伏強度が１２５ＭＰａ以上である鋼板を得ることができる。また、前記連続焼鈍ライン（ＣＡＬまたはＣＡＰＬ）等のプロセスで熱処理を施した後、溶融亜鉛めっきラインもしくは電気めっきラインで亜鉛めっきを付与、または、前記連続溶融亜鉛めっきライン（ＣＧＬ）のプロセスで熱処理及び溶融亜鉛めっきを付与することによって、５００℃における降伏強度が２５０ＭＰａ以上、かつ、６００℃における降伏強度が１２５ＭＰａ以上である亜鉛めっき鋼板を得ることができる。得られた鋼板及び亜鉛めっき鋼板を所定の大きさ、形状に加工して、鋼板下地材として用いることができる。 For example, first, steel with a desired chemical composition is cast, the cast steel is hot rolled, pickled, and cold rolled, and then transferred to a continuous annealing line (CAL or CAPL) or a continuous hot-dip galvanizing line. (CGL) or the like, it is possible to obtain a steel plate having a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C. In addition, after heat treatment is performed in a process such as the continuous annealing line (CAL or CAPL), galvanization is applied in a hot-dip galvanizing line or electroplating line, or heat treatment is carried out in the process of the continuous hot-dip galvanizing line (CGL). By applying hot-dip galvanizing, it is possible to obtain a galvanized steel sheet having a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C. The obtained steel sheet and galvanized steel sheet can be processed into a predetermined size and shape and used as a steel sheet base material.
　前記冷延鋼板の熱処理の条件は、前記鋼の化学組成や、前記冷間圧延の条件により適宜変更することができるため、特に限定されないが、例えば、冷延鋼板を常温から６５０～９００℃の焼鈍温度まで加熱し、焼鈍温度で１～１８００ｓ保持することが好ましい。この焼鈍処理により、鋼板の組織において、再結晶組織の面積率を２０％未満とすることができる。焼鈍温度は、好ましくは６８０℃以上であり、また、好ましくは８８０℃以下である。また、焼鈍温度での保持時間（焼鈍時間）は、好ましくは５ｓ以上であり、また、好ましくは１５００ｓ以下である。 The conditions for heat treatment of the cold rolled steel sheet are not particularly limited as they can be changed as appropriate depending on the chemical composition of the steel and the conditions of the cold rolling. It is preferable to heat to the annealing temperature and hold at the annealing temperature for 1 to 1800 seconds. By this annealing treatment, the area ratio of the recrystallized structure can be made less than 20% in the structure of the steel sheet. The annealing temperature is preferably 680°C or higher, and preferably 880°C or lower. Further, the holding time at the annealing temperature (annealing time) is preferably 5 s or more, and preferably 1500 s or less.
　焼鈍処理後の鋼板は、６００～４００℃まで、冷却速度３～１００℃／ｓで冷却することが好ましい。 The steel plate after the annealing treatment is preferably cooled to 600 to 400°C at a cooling rate of 3 to 100°C/s.
　本明細書は、上述したように様々な態様の技術を開示しているが、そのうち主な技術を以下にまとめる。 This specification discloses techniques in various aspects as described above, and the main techniques are summarized below.
　上述したように、本発明の一局面に係る鋼製下地材は、５００℃における降伏強度が２５０ＭＰａ以上、かつ、６００℃における降伏強度が１２５ＭＰａ以上である鋼板を有する。 As described above, the steel base material according to one aspect of the present invention includes a steel plate having a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C.
　このような構成の鋼板を鋼製下地材として用いることによって、鋼製下地材および耐火被覆材を備える建築物の耐火構造において、使用する耐火被覆材が少なくても耐火性能を確保することが可能な鋼製下地材を提供することができる。 By using a steel plate with this structure as a steel base material, it is possible to ensure fire resistance performance even if less fire-resistant sheathing is used in the fire-resistant structure of a building that has a steel base material and fire-resistant sheathing material. It is possible to provide a steel base material with a high quality.
　上記構成の鋼製下地材における前記鋼板は、室温での降伏強度が２５０ＭＰａ以上であってもよい。 The steel plate in the steel base material having the above structure may have a yield strength of 250 MPa or more at room temperature.
　このような構成の鋼板を鋼製下地材として用いることによって、耐火性能を確保するだけでなく、室温においてより十分な強度も確保することが可能な鋼製下地材を提供することができる。 By using a steel plate with such a configuration as a steel base material, it is possible to provide a steel base material that not only ensures fire resistance but also ensures sufficient strength at room temperature.
　上記構成の鋼製下地材は、さらに、前記鋼板の表面に形成された金属めっきを有してもよい。 The steel base material having the above structure may further have metal plating formed on the surface of the steel plate.
　〈試料〉
　試料は、以下に説明する鋼板Ａと鋼板Ｂを使用した。鋼板Ａは、比較例であり、ＪＩＳ　Ｇ　３３０２：２０１９に規定されている市販の溶融亜鉛めっき鋼板（ＳＧＣＣ）で、Ｎｂ（ニオブ）、Ｔｉ（チタン）、Ｖ（バナジウム）が添加されていないものである。また、鋼板Ｂは、その成分組成として、Ｃ（炭素）：０．０６質量％、Ｓｉ（ケイ素）：０．０２質量％、Ｍｎ（マンガン）：１．４５質量％、Ｎｂ（ニオブ）０．０２質量％、Ｔｉ（チタン）：０．０４質量％を含み、残部がＦｅ（鉄）及び不可避的不純物であり、下記の製造条件でラボ作製した冷延鋼板であり、本実施形態の要件を満たす本発明例である。 <sample>
Steel plates A and B, which will be explained below, were used as samples. Steel plate A is a comparative example, and is a commercially available hot-dip galvanized steel plate (SGCC) specified in JIS G 3302:2019, to which Nb (niobium), Ti (titanium), and V (vanadium) are not added. It is. Further, the steel plate B has a component composition of C (carbon): 0.06% by mass, Si (silicon): 0.02% by mass, Mn (manganese): 1.45% by mass, and Nb (niobium) 0. The cold-rolled steel sheet contains 0.02% by mass, Ti (titanium): 0.04% by mass, and the remainder is Fe (iron) and unavoidable impurities, and was manufactured in a laboratory under the following manufacturing conditions, and meets the requirements of this embodiment. This is an example of the present invention that satisfies the above requirements.
　製造条件
　・熱延条件、冷延条件
　スラブを１２００℃で加熱し、３．６ｍｍまで圧延し、巻取りを模擬するため５５０℃の保持炉に挿入し、３０分保持後、炉冷した。冷却した熱延鋼板の表裏面を研削して１．６ｍｍとした。これは実際の製造設備で、１．６ｍｍの熱延鋼板を模擬するためのラボ上のプロセスである。その後、１．６ｍｍの熱延鋼板を０．８ｍｍまで冷間圧延した。 Manufacturing conditions - Hot rolling conditions, cold rolling conditions The slab was heated at 1200°C, rolled to 3.6 mm, inserted into a holding furnace at 550°C to simulate winding, held for 30 minutes, and then cooled in the furnace. The front and back surfaces of the cooled hot-rolled steel plate were ground to 1.6 mm. This is a laboratory process to simulate 1.6 mm hot-rolled steel sheets in actual manufacturing equipment. Thereafter, the 1.6 mm hot rolled steel plate was cold rolled to 0.8 mm.
　・焼鈍条件
　冷延鋼板を、７００℃において６０ｓ保持し、冷却速度１０℃／ｓで２００℃以下まで冷却し、その後、放冷し、鋼板Ｂを得た。鋼板Ｂは亜鉛めっき鋼板の理想的な状態をラボで検証するために、めっきを付与していない。 - Annealing conditions The cold rolled steel plate was held at 700°C for 60 seconds, cooled to 200°C or less at a cooling rate of 10°C/s, and then allowed to cool to obtain steel plate B. Steel plate B was not coated in order to verify the ideal state of a galvanized steel plate in a laboratory.
　なお、製造した鋼板Ｂの再結晶組織の面積率は０．５％であった。なお、鋼板Ａにおける鋼板の再結晶組織の面積率は１００％であった。再結晶組織の面積率は、光学顕微鏡を用いて撮影した鋼板の写真を使用して求めた。 Note that the area ratio of the recrystallized structure of the manufactured steel sheet B was 0.5%. In addition, the area ratio of the recrystallized structure of the steel sheet A was 100%. The area ratio of the recrystallized structure was determined using a photograph of the steel plate taken using an optical microscope.
　〈評価〉
　鋼板Ａ、鋼板Ｂから、ＪＩＳ　Ｚ　２２４１：２０２２で規定されるＪＩＳ１３Ｂ号の引張試験片を採取し、ＪＩＳ　Ｇ　０５６７：２０２０に準じて２０℃～７５０℃の各温度で引張試験を行い、降伏強度を測定した。１００℃以上の温度では、各温度で１０分間保持した後、引張試験を行った。引張試験機での引張速度は降伏強度まで０．００４ｍｉｎ－１とした。 <evaluation>
JIS 13B tensile test pieces specified in JIS Z 2241:2022 were taken from steel plates A and B, and tensile tests were conducted at various temperatures from 20°C to 750°C in accordance with JIS G 0567:2020 to determine the yield strength. was measured. At temperatures of 100° C. or higher, tensile tests were conducted after holding each temperature for 10 minutes. The tensile speed in the tensile tester was set at 0.004 min -1 up to yield strength.
　図１は、降伏強度と温度との関係を示すグラフである。鋼板Ａの２０℃における降伏強度は１５９ＭＰａであり、５００℃における降伏強度は１２３ＭＰａであり、６００℃における降伏強度は１０１ＭＰａである。鋼板Ｂの２０℃における降伏強度は９０１ＭＰａであり、５００℃における降伏強度は３８２ＭＰａであり、６００℃における降伏強度は１６７ＭＰａである。図１より、鋼板Ｂの方が、鋼板Ａに比べて各温度における降伏強度が高く、特に５００℃および６００℃の高温における降伏強度に優れることがわかる。 FIG. 1 is a graph showing the relationship between yield strength and temperature. The yield strength of steel plate A at 20°C is 159 MPa, the yield strength at 500°C is 123 MPa, and the yield strength at 600°C is 101 MPa. The yield strength of steel plate B at 20°C is 901 MPa, the yield strength at 500°C is 382 MPa, and the yield strength at 600°C is 167 MPa. From FIG. 1, it can be seen that steel plate B has higher yield strength at each temperature than steel plate A, and is particularly excellent in yield strength at high temperatures of 500°C and 600°C.
　次に、鋼板Ａ、鋼板Ｂを鋼製下地材として用いたときの加熱による変型挙動について、有限要素解析（ＦＥＭ）によるシミュレーションを行った。ＦＥＭには、上記の測定値に加え、鋼板Ａ、鋼板Ｂの縦弾性率、横弾性率および線膨張係数を使用した。 Next, a simulation was performed using finite element analysis (FEM) to examine the deformation behavior caused by heating when steel plates A and B were used as steel base materials. In addition to the above measured values, the longitudinal elastic modulus, transverse elastic modulus, and linear expansion coefficient of steel plates A and B were used for the FEM.
　ＦＥＭによるシミュレーションの条件は、以下の通りとした。加熱面を四角筒形状の鋼製下地材の１つの面のみとしたのは、火災時の加熱状態を模したものだからである。
　鋼製下地材の寸法、形状
　・板厚：０．８ｍｍ
　・断面：一辺の長さ４５ｍｍの正方形
　・長さ：２０００ｍ
　・加熱面：４つの側面のうち１つのみ
　・拘束条件：鋼製下地材の長手方向両端を拘束
　・加熱開始時間からの時間ｔ（ｍｉｎ）における各面の温度Ｔ（℃）
　・加熱面：Ｔ（ｔ）＝９００×ｌｏｇ１０（１＋０．０８ｔ）
　・加熱面に対向する面：Ｔ（ｔ）＝９００×ｌｏｇ１０（１＋０．０４５（ｔ－５））、ただし、加熱開始から５分までは室温（２０℃）
　・温度Ｔ（℃）における鋼板Ａおよび鋼板Ｂの縦弾性率Ｅ（ｋｇｆ／ｃｍ２）および横弾性率Ｇ（ｋｇｆ／ｃｍ２）
　・縦弾性率Ｅ：Ｅ＝２．１４×１０６×ｅｘｐ（－０．０００３７４Ｔ）
　・横弾性率Ｇ：Ｇ＝８．３０×１０６×ｅｘｐ（－０．０００４０９Ｔ）
　・鋼板Ａ、Ｂの線膨張係数α(１／℃）：α＝０．００００１２ The conditions for the FEM simulation were as follows. The reason why the heating surface was only one surface of the rectangular cylindrical steel base material was to simulate the heating state during a fire.
Dimensions and shape of steel base material ・Plate thickness: 0.8mm
・Cross section: square with side length 45mm ・Length: 2000m
・Heating surface: Only one of the four sides ・Restriction condition: Both ends of the steel base material in the longitudinal direction are restrained ・Temperature T (°C) of each surface at time t (min) from the heating start time
・Heating surface: T(t)=900×log 10 (1+0.08t)
・Surface facing the heating surface: T(t)=900×log 10 (1+0.045(t-5)), but at room temperature (20°C) for 5 minutes from the start of heating
・Longitudinal elastic modulus E (kgf/cm 2 ) and transverse elastic modulus G (kgf/cm 2 ) of steel plate A and steel plate B at temperature T (°C)
・Longitudinal elastic modulus E: E=2.14×10 6 ×exp (-0.000374T)
・Transverse elastic modulus G: G=8.30×10 6 ×exp (-0.000409T)
・Linear expansion coefficient α (1/℃) of steel plates A and B: α=0.000012
　また、参考例として、降伏強度がない完全弾性体についてもＦＥＭを行った。 Additionally, as a reference example, FEM was also performed on a perfectly elastic body with no yield strength.
　図２は、上記ＦＥＭによって求めた、加熱時間（秒）と加熱面の長さ方向の歪み量との関係を示すグラフである。図２によると、比較例の鋼板Ａは、加熱開始後約６００ｓで塑性変形（座屈）を開始した。一方、本発明例の鋼板Ｂは、加熱開始後約１８００ｓで塑性変形を開始した。これらのことから、鋼板Ｂは、鋼板Ａに比べて耐火性能に優れていることがわかる。なお、図２から、参考例の完全弾性体では、塑性変形は生じていないことがわかる。 FIG. 2 is a graph showing the relationship between the heating time (seconds) and the amount of strain in the length direction of the heating surface, as determined by the FEM described above. According to FIG. 2, steel plate A of the comparative example started plastic deformation (buckling) about 600 seconds after the start of heating. On the other hand, steel plate B of the present invention example started plastic deformation approximately 1800 seconds after the start of heating. From these facts, it can be seen that steel plate B has superior fire resistance performance compared to steel plate A. Note that from FIG. 2 it can be seen that no plastic deformation occurs in the perfectly elastic body of the reference example.
　この出願は、２０２２年９月２２日に出願された日本国特許出願特願２０２２－１５１２７１号を基礎とするものであり、その内容は、本願に含まれるものである。 This application is based on Japanese Patent Application No. 2022-151271 filed on September 22, 2022, and its contents are included in the present application.
　本発明を表現するために、前述において具体例や図面等を参照しながら実施形態を通して本発明を適切かつ十分に説明したが、当業者であれば前述の実施形態を変更及び／又は改良することは容易になし得ることであると認識すべきである。したがって、当業者が実施する変更形態又は改良形態が、請求の範囲に記載された請求項の権利範囲を離脱するレベルのものでない限り、当該変更形態又は当該改良形態は、当該請求項の権利範囲に包括されると解釈される。 In order to express the present invention, the present invention has been appropriately and fully explained through the embodiments above with reference to specific examples, drawings, etc., but those skilled in the art will be able to modify and/or improve the above-described embodiments. It should be recognized that this can be done easily. Therefore, unless the modification or improvement carried out by a person skilled in the art does not leave the scope of the claims stated in the claims, such modifications or improvements do not fall outside the scope of the claims. It is interpreted as encompassing.
　本発明は、建築物に使用される鋼製下地材に関する技術分野において、広範な産業上の利用可能性を有する。

  INDUSTRIAL APPLICATION This invention has wide industrial applicability in the technical field regarding the steel base material used for a building.

Claims (3)

  1. 　５００℃における降伏強度が２５０ＭＰａ以上、かつ、６００℃における降伏強度が１２５ＭＰａ以上である鋼板を有する、鋼製下地材。 A steel base material having a steel plate having a yield strength of 250 MPa or more at 500°C and a yield strength of 125 MPa or more at 600°C.
  2. 　前記鋼板は、室温での降伏強度が２５０ＭＰａ以上である、請求項１に記載の鋼製下地材。 The steel base material according to claim 1, wherein the steel plate has a yield strength of 250 MPa or more at room temperature.
  3. 　さらに、前記鋼板の表面に形成された金属めっきを有する、請求項１または請求項２に記載の鋼製下地材。

          The steel base material according to claim 1 or 2, further comprising metal plating formed on the surface of the steel plate.
PCT/JP2023/034188 2022-09-22 2023-09-21 Steel base material WO2024063113A1 (en)

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JP2007056348A (en) * 2005-08-26 2007-03-08 Nippon Steel Corp Steel plate easily processed for bending by linear heating, and method for producing the same
CN103334061A (en) * 2013-06-18 2013-10-02 上海大学 Die-casting die steel with high heat conductivity and large section and preparation and heat treatment method thereof

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Publication number Priority date Publication date Assignee Title
JPH04193907A (en) * 1990-11-27 1992-07-14 Kobe Steel Ltd Production of 50kgf/mm2 class refractory steel plate for construction use
JPH04350120A (en) * 1991-05-29 1992-12-04 Kobe Steel Ltd Production of high strength refractory steel plate for construction use
JPH08104965A (en) * 1994-10-03 1996-04-23 Nisshin Steel Co Ltd Production of hot-dip zinc aluminum alloy plated steel sheet for fire-resistant structure excellent in corrosion resistance
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JP2007056348A (en) * 2005-08-26 2007-03-08 Nippon Steel Corp Steel plate easily processed for bending by linear heating, and method for producing the same
CN103334061A (en) * 2013-06-18 2013-10-02 上海大学 Die-casting die steel with high heat conductivity and large section and preparation and heat treatment method thereof

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