WO2016006232A1 - Corps moulé à la presse à chaud ainsi que procédé de fabrication de celui-ci, et tôle d'acier plaquée pour corps moulé à la presse à chaud - Google Patents

Corps moulé à la presse à chaud ainsi que procédé de fabrication de celui-ci, et tôle d'acier plaquée pour corps moulé à la presse à chaud Download PDF

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Publication number
WO2016006232A1
WO2016006232A1 PCT/JP2015/003426 JP2015003426W WO2016006232A1 WO 2016006232 A1 WO2016006232 A1 WO 2016006232A1 JP 2015003426 W JP2015003426 W JP 2015003426W WO 2016006232 A1 WO2016006232 A1 WO 2016006232A1
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Prior art keywords
steel sheet
plating
hot press
layer
hot
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PCT/JP2015/003426
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English (en)
Japanese (ja)
Inventor
泰明 沖田
池田　倫正
公一 谷口
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JFE Steel Corp
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JFE Steel Corp
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Priority to JP2015551289A priority Critical patent/JP6146482B2/ja
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/20—Deep-drawing
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C18/00—Alloys based on zinc
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C18/00—Alloys based on zinc
    • C22C18/04—Alloys based on zinc with aluminium as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on 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
    • 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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur

Definitions

  • the present invention relates to a hot press-formed body excellent in resistance spot weldability, a manufacturing method thereof, and a plated steel sheet for a hot press-formed body.
  • Patent Document 1 a material (steel plate) to be formed is preheated and softened so as to facilitate press working, and then the heated steel plate is formed using a die and a die and rapidly cooled at the same time.
  • hot press molding the process of heating and then molding and cooling at the same time is referred to as hot press molding
  • a molding technique that makes it easy to mold and achieve high strength is disclosed.
  • heating the steel plate to a high temperature of Ac3 or higher before forming is necessary to obtain high strength after press forming. For this reason, scale (iron oxide) is generated on the surface of the steel sheet, and the scale peels off during hot press forming, damaging the mold or damaging the surface of the compact after hot press forming. is there.
  • the scale remaining on the surface of the molded body not only causes poor appearance and poor paint adhesion, but also has high electrical resistance, which makes resistance spot welding mainly used in the assembly of car bodies difficult. There's a problem. For this reason, the scale on the surface of the molded body is usually removed by a treatment such as pickling or shot blasting, but this complicates the manufacturing process and causes a decrease in productivity.
  • an Al-based plated steel sheet As a conventional hot-pressed plated steel sheet, for example, as described in Patent Document 2, an Al-based plated steel sheet has been often used.
  • Fe rapidly diffuses into the plating layer when heated in the austenite region to form an alloy layer of Al and Fe, and resistance spot welding is performed without performing pickling or shot blasting. Is possible.
  • the Al—Fe alloy layer is hard and brittle, there are problems in that it is peeled off during processing to reduce processing productivity and shorten the mold life.
  • Patent Document 3 discloses a Zn—Fe-based compound that prevents corrosion and decarburization during heating when a steel sheet coated with Zn or a Zn-based alloy is formed into a hot press-formed body, and has a lubricating function. And a method for producing an alloy compound such as a Zn—Fe—Al based compound on the surface of a steel sheet. It has been shown that a member manufactured by this method, particularly a member using a steel sheet coated with Zn-50 to 55 mass% Al, can obtain an excellent corrosion prevention effect.
  • Patent Document 4 discloses a hot pressed member in which a plated layer containing a Fe—Zn solid solution phase is formed on the surface of the member after hot pressing using an alloyed hot-dip Zn plated steel sheet. It has been shown that this hot press member can provide excellent hot press workability (coating layer adhesion), corrosion resistance, and weldability.
  • the present invention provides a hot press-formed body excellent in resistance spot weldability that does not require a step of removing oxides by shot blasting or the like, a manufacturing method thereof, and a plated steel sheet for hot press. With the goal.
  • the present inventors have intensively studied to solve the above problems. As a result, the following knowledge was obtained.
  • a hot press-molded body with plating obtained by heating a plated steel sheet to a temperature equal to or higher than the Ac3 transformation point of the plated steel sheet, and then simultaneously cooling the plated steel sheet using a mold.
  • On the surface of the plating there is an oxide layer having a network-like unevenness with an average roughness Ra of 2 ⁇ m or more and an average thickness of 3 ⁇ m or less, and under the oxide layer, A hot press-formed body having a plating layer having a melting point equal to or lower than the heating temperature.
  • the density of a plating layer is evaluated by the density of main components constituting the plating layer.
  • the main component means a component exceeding 50% by weight.
  • the density of the oxide layer refers to the density of the oxide formed from the main components constituting the plating layer.
  • a steel sheet having a plating layer used for a hot press-formed body is generically called a hot-press formed body plated steel sheet. Therefore, the plated steel sheet for hot press-formed bodies of the present invention has a plating layer regardless of whether or not the alloying treatment is performed after the plating treatment. That is, the plated steel sheet for hot press-formed body in the present invention is a hot dip galvanized steel sheet that has not been subjected to alloying treatment, an alloyed hot dip galvanized steel sheet that has been alloyed, It includes galvanized steel sheets, hot dip zinc-aluminum alloy plated steel sheets, aluminum plated steel sheets and the like.
  • the hot press molding excellent in resistance spot weldability which does not require the process of removing an oxide by shot blasting etc. is obtained.
  • processing can be performed without causing galling or breakage of the steel sheet, and it is not necessary to remove scale such as shot blasting. Cost reduction is possible.
  • FIG. 1 is a cross-sectional view of a plated layer of a hot press-formed body obtained by hot pressing at an inappropriate heating temperature using a Zn-based plated steel sheet.
  • FIG. 2 is a cross-sectional view of a plated layer of a hot press-formed body using a Zn-based plated steel sheet.
  • FIG. 3 is a cross-sectional view of a plating layer of a hot press-formed body using an Al-based plated steel sheet.
  • FIG. 4 is a diagram used for explaining the press molding method.
  • the hot press-formed body excellent in resistance spot weldability according to the present invention is obtained by heating a plated steel sheet to a temperature equal to or higher than the Ac3 transformation point of the plated steel sheet, and then forming it using a mold and cooling it at the same time. It is a hot press-molded product.
  • the surface of the plating has an oxide layer with mesh-like irregularities, and under the oxide layer, there is a plating layer whose melting point is equal to or lower than the heating temperature during hot press molding. It is characterized by.
  • the hot press-formed body of the present invention has a wide appropriate current range in resistance spot welding and is excellent in resistance spot weldability.
  • the plated steel sheet In oxide layer hot press forming with mesh-like irregularities, the plated steel sheet must be heated to 3 or more points (usually 800 ° C to 1000 ° C) on the plated steel plate, and plating oxide is formed on the plated surface. Is done.
  • Zn-based plating ZnO having a high electric resistance value is formed thick on the surface, and this is the cause, and when the obtained hot press-molded body is resistance spot welded, scattering is likely to occur.
  • the appropriate current range for spot welding may be narrow.
  • the heating temperature is lower than the melting point of Zn-Ni plating.
  • a flat ZnO layer is formed on the plating surface (Fig. 1), and even if resistance spot welding is performed on a plate assembly in which two hot press materials are stacked, the ZnO layer is energized between the steel plates. Path formation may be hindered and there may be no current flow.
  • the oxide formed on the plating surface of the hot press-molded body is an oxide exhibiting a high electrical resistance
  • resistance spot welding is performed when the oxide on the plating surface forms a mesh-like unevenness. It becomes possible. This is due to the following reason.
  • a plate assembly in which a hot press-molded body in which the oxide on the plating surface forms a mesh-like unevenness is sandwiched between at least one of the two or more superposed steel sheets is sandwiched between a pair of electrodes, and the pressure is applied. Resistance spot welding is performed while adding. In this case, at the position where the electrode pressing force is applied, the conductive layer is formed by the collapse of the uneven oxide layer, and resistance spot welding becomes possible. From the above, in the present invention, the surface of the plating has an oxide layer having a mesh-like unevenness.
  • the oxide layer having mesh-like irregularities has an average roughness Ra of 2 ⁇ m or more and an average thickness of 3 ⁇ m or less.
  • Ra is less than 2 ⁇ m, the unevenness is small and the oxide layer does not collapse sufficiently even when pressed by an electrode, so that it is difficult to secure an energization path.
  • Further preferable Ra is 3 ⁇ m or more.
  • the average thickness of the oxide layer exceeds 3 ⁇ m, even if there is an unevenness with Ra of 2 ⁇ m or more, the thickness of the oxide layer is too thick. It becomes difficult to ensure.
  • the oxide layer having mesh-like irregularities is formed on the surface of the plating while heating the plated steel sheet.
  • the oxide layer formed during this heat treatment is subjected to a high load by subsequent molding.
  • unevenness exists on the surface of the oxide layer, the unevenness partially collapses due to this load to form a discontinuous oxide layer, and an energization path during resistance spot welding is secured.
  • scattering is less likely to occur, a wide appropriate current range can be obtained, and resistance spot weldability is further improved. Therefore, it is preferable that a discontinuous oxide layer is present on the plating surface.
  • the oxide layer having such network-like irregularities uses, for example, plating in which the density of the main component constituting the plating layer is higher than the density of the oxide formed from the main component constituting the plating layer, and It can be formed by heating the heating temperature of the hot press to a temperature higher than the melting point of the plating layer.
  • the density of Zn is the 7.14 g / cm 3 (room temperature), 600 density of 6.81 g / cm 3, ZnO in the molten state of °C is 5.61 g / cm 3 (room temperature) .
  • ZnO network-like irregularities are formed on the plating surface. Is done.
  • the Al density is 2.70 g / cm 3 (room temperature) and the Al 2 O 3 density is 3.95 g / cm 3 (room temperature).
  • the plating no mesh-like irregularities like Zn-based are formed.
  • a plating layer whose melting point is lower than the heating temperature during hot press forming has a plating layer that is lower than the heating temperature under the oxide layer without being lost due to oxidation during the heat treatment or diffusion to the steel sheet. If the plating layer melts in the initial stage of resistance spot welding, the oxide layer with high electrical resistance formed on the plating layer collapses, and further collapses from the pressurized part with the molten plating. The oxide layer thus discharged is discharged, and a stable wide energization path is formed. As a result, scattering does not easily occur and a wide appropriate current range can be obtained.
  • having a plating layer means observing the cross section of the plating layer of any 10 fields of view with a SEM backscattered electron image at a magnification of 500 times, and the plating layer is present on 50% or more of the steel sheet surface excluding the oxide layer. Suppose you are.
  • an oxide layer having irregularities can be formed by using plating in which the density of the main component constituting the plating layer is higher than the density of the oxide formed from the main component constituting the plating layer. it can. From this point, Zn plating is preferable as the plating. In the case of Zn-based plating, the sacrificial corrosion resistance of Zn to Fe can also have excellent corrosion resistance. In the case where the remainder of the plating layer other than Zn contains components such as Al and Mg, the density of Al and Mg is lower than the density of oxides such as Al and Mg, and there is a tendency to ionize Al and Mg.
  • the components such as Al and Mg are present in a small amount in the plating phase.
  • Al is preferably 10% or less. More preferably, Al is 0.1% or less.
  • Inevitable impurities are acceptable if Mg: less than 1.0% and Si: less than 1.0%. In this way, Mg: less than 1.0%, Si: less than 1.0%, the adhesion of dross is reduced, the occurrence of cracks in the plating layer during hot press molding is reduced, and the advantage of excellent workability There is.
  • the plating that can be suitably used is a plating containing Al: 10% or less and Fe: 20% or less in mass%, with the balance being made of Zn and inevitable impurities.
  • Another plating that can be suitably used is a plating containing Ni: 10 to 25%, with the balance being Zn and inevitable impurities.
  • the adhesion amount is preferably 10 to 90 g / m 2 .
  • Any of Ni 2 Zn 11 , ZiZn 3 , and Zi 5 Zn 21 is contained in the component contained in the balance other than Zn by containing Ni that has an ionization tendency lower than that of Zn and does not inhibit the formation of irregularities on the surface of the plating layer.
  • a gamma phase having a crystal structure of 1 and a very high melting point of 881 ° C. is formed. Thereby, excessive zinc oxide formation on the plating layer surface in the heating process can be suppressed.
  • the zinc oxide layer Even if the zinc oxide layer has irregularities, it will hinder the energization path in resistance spot welding, so it is preferable that the zinc oxide layer is thin, and the energization path is more effective by suppressing excessive zinc oxide formation. Secured. Furthermore, since the plating layer remains as a ⁇ phase even after hot press forming is completed, it exhibits excellent perforated corrosion resistance due to the sacrificial anticorrosive effect of Zn, and the ⁇ phase melts at the initial stage of energization of resistance spot welding. Contributes to the expansion and stabilization of routes.
  • the formation of the ⁇ phase at a Ni content of 10 to 25% does not necessarily match the equilibrium diagram of the Ni—Zn alloy, but this is a non-equilibrium progress of the plating layer formation reaction performed by electroplating or the like. It is thought to do.
  • the coating layer I has an adhesion amount of 0.01-5 g / m 2 and 10-25% Ni. It is preferable that the plating layer has a structure in which the balance is made of Zn and inevitable impurities, and the plating layer II has an adhesion amount of 10 to 90 g / m 2 . If the amount of Ni in the plating layer I is less than 60%, it is not possible to sufficiently suppress the diffusion of Zn in the plating layer into the underlying steel sheet, so that excellent perforated corrosion resistance may not be obtained.
  • the Ni content of the plating layer I is 60% or more, the diffusion of Zn in the plating layer to the underlying steel sheet is suppressed, and many ⁇ phases remain after hot press forming, contributing to the expansion of the appropriate current range for resistance spot welding. To do.
  • the amount of Ni in the plating layer I is preferably 100%. In the case of less than 100%, the balance is Zn and an unavoidable impurity having a sacrificial anticorrosive effect.
  • the adhesion amount per one side of the plating layer I is less than 0.01 g / m 2 , the effect of suppressing the diffusion of Zn into the underlying steel sheet is not sufficiently exhibited. If it exceeds 5 g / m 2 , the effect will be saturated and the cost will increase. Therefore, 0.01 to 5 g / m 2 is set.
  • the plating layer II is a plating layer containing 10 to 25% of Ni and the balance of Zn and inevitable impurities.
  • a ⁇ phase having a high melting point of 881 ° C. having a crystal structure of Ni 2 Zn 11 , NiZn 3 , or Ni 5 Zn 21 is formed.
  • Excessive zinc oxide formation on the plating layer surface during the heating process can be suppressed. Even if the zinc oxide layer has irregularities, it will hinder the energization path in resistance spot welding, so it is preferable that the zinc oxide layer is thin, and the energization path is more effective by suppressing excessive zinc oxide formation. Secured.
  • the plating layer II remains as a ⁇ phase even after the hot press forming is completed, excellent perforated corrosion resistance is exhibited due to the sacrificial anticorrosive effect of Zn.
  • the formation of the ⁇ phase when the Ni content is 10 to 25% by mass does not necessarily match the equilibrium diagram of the Ni—Zn alloy. This is probably because the formation reaction of the plating layer performed by electroplating or the like proceeds in a non-equilibrium manner.
  • the adhesion amount per one side of the plating layer II is less than 10 g / m 2 , the sacrificial anticorrosive effect of Zn is not sufficiently exhibited. If it exceeds 90 g / m 2 , the effect is saturated and the cost is increased. Therefore, it is set to 10 to 90 g / m 2 .
  • the method for forming such plating layer I and plating layer II is not particularly limited. Known electroplating methods are preferred.
  • the ⁇ phase of Ni 2 Zn 11 , NiZn 3 , and Ni 5 Zn 21 can be confirmed by an X-ray diffraction method or an electron beam diffraction method using TEM (Transmission Electron Microscopy). Further, although the ⁇ phase is formed as described above by setting the Ni content of the plating layer II to 10 to 25 mass%, some ⁇ phase may be mixed depending on the conditions of electroplating. At this time, in order to minimize the zinc oxide formation reaction on the surface of the plating layer during the heating process, the amount of ⁇ phase is preferably 5% by mass or less. The amount of the ⁇ phase is defined by the mass ratio of the ⁇ phase to the total mass of the plating layer II, and can be quantified by, for example, the anodic dissolution method.
  • the plated steel sheet for hot press-formed bodies of the present invention preferably has a plated layer on the steel sheet surface, and the density of the plated layer is preferably higher than the density of the oxide formed from the main components constituting the plated layer.
  • the plating layer preferably contains, by mass%, Al: 10% or less, Fe: 20% or less, and the balance of Zn and inevitable impurities.
  • Ni: 10 to 25% is contained, the balance is made of Zn and inevitable impurities, and the adhesion amount is 10 to 90 g / m 2 .
  • the plating layer contains, in order from the steel plate surface, in mass%, Ni: 60% or more, the balance consisting of Zn and unavoidable impurities, and an adhesion amount of 0.01 to 5 g / m 2 and mass. It is preferable to have a plating layer II containing Ni: 10 to 25%, the balance being Zn and inevitable impurities, and having an adhesion amount of 10 to 90 g / m 2 .
  • Hot-rolled steel sheets and cold-rolled steel sheets can be used as the plated steel sheets for hot press-formed bodies.
  • Component composition is mass%, C: 0.15-0.5%, Si: 0.05-2.0%, Mn: 0.5-3%, P: 0.1% or less, S: 0.05% or less, Al: 0.1% or less, N: 0.01 % Or less, with the balance being Fe and inevitable impurities.
  • it contains at least one selected from Cr: 0.01 to 1%, Ti: 0.2% or less, and B: 0.0005 to 0.08%, or Sb: 0.003 to 0.03% by mass.
  • the tensile strength (henceforth TS may be called) 980 Mpa or more can be provided to a hot press molding.
  • C 0.15-0.5% C is an element that improves the strength of the steel.
  • the C content needs to be 0.15% or more.
  • the amount of C exceeds 0.5%, the blanking workability of the steel plate as the material will be significantly reduced. Therefore, the C content is 0.15 to 0.5%.
  • Si 0.05-2.0% Si, like C, is an element that improves the strength of steel.
  • the Si amount needs to be 0.05% or more.
  • the amount of Si exceeds 2.0%, the occurrence of surface defects called red scale during hot rolling significantly increases, the rolling load increases, and the ductility of the hot-rolled steel sheet deteriorates.
  • the Si content exceeds 2.0%, the plating processability may be adversely affected when a plating process for forming a plating film mainly composed of Zn or Al on the steel sheet surface is performed. Therefore, the Si content is 0.05 to 2.0%.
  • Mn 0.5-3.0%
  • Mn is an element effective for suppressing the ferrite transformation and improving the hardenability.
  • the Ac3 transformation point is lowered, it is an effective element for lowering the heating temperature before hot pressing.
  • the amount of Mn needs to be 0.5% or more.
  • the amount of Mn exceeds 3.0%, segregation occurs and the uniformity of the properties of the raw steel plate and hot press-formed product decreases. Therefore, the Mn content is 0.5 to 3.0%.
  • the P content is 0.1% or less. More preferably, in order to improve the cross tensile strength of the resistance spot welded portion, the P content is 0.02% or less.
  • Al 0.1% or less
  • the Al content is 0.1% or less.
  • N 0.01% or less
  • the balance is Fe and inevitable impurities.
  • Cr 0.01 to 1%
  • Ti 0.2% or less
  • B 0.0005 to 0.08% and / or Sb: 0.003 to 0.03%
  • Cr 0.01-1%
  • the Cr content is preferably 0.01% or more.
  • the upper limit of the Cr content is preferably 1%.
  • Ti 0.2% or less Ti is an element effective for strengthening steel and improving toughness by refining. It is also an element effective for forming a nitride in preference to B and exhibiting the effect of improving the hardenability by the solid solution B. However, if the amount of Ti exceeds 0.2%, the rolling load during hot rolling is extremely increased, and the toughness of the hot press-formed product is reduced, so the upper limit of the amount of Ti is preferably 0.2%. .
  • B 0.0005-0.08%
  • B is an element effective for improving the hardenability during hot pressing and toughness after hot pressing.
  • the B content is preferably 0.0005% or more.
  • the upper limit is preferably 0.08%.
  • Sb has an effect of suppressing a decarburized layer generated in the surface layer portion of the steel plate after the steel plate is heated until the steel plate is cooled by a series of hot press processes.
  • the amount of Sb is preferably 0.003% or more.
  • the upper limit of the Sb amount is preferably 0.03%.
  • Hot press-formed hot press with excellent resistance spot weldability by heating the plated steel sheet for hot press-formed body composed of the above at a temperature equal to or higher than the Ac3 transformation point of the plated steel sheet and then forming using a mold.
  • a shaped body is produced.
  • Heating is preferably performed at an average temperature increase rate of 50 ° C./s or more. More preferably, the average rate of temperature increase is 100 ° C./s or more, and still more preferably 110 ° C./s or more.
  • the average rate of temperature increase is the average rate of temperature increase from room temperature (20 ° C.) to the heating temperature, ((heating temperature) ⁇ room temperature (20 ° C.)) / (Temperature increasing time). Can be sought.
  • the heating is performed at a temperature higher than the Ac3 transformation point is to form a hard phase such as a martensite phase by rapid cooling during hot pressing and to increase the strength of the hot press-formed body.
  • the reason why the plating layer is heated to the melting point or higher is to melt the plating layer and form irregularities in the oxide of the plating layer formed on the surface.
  • the heating temperature exceeds 1000 ° C, a large amount of oxide layer is formed on the surface of the plating layer, and even if unevenness is formed on the oxide layer, it is a very thick oxide that hinders the formation of a current path during resistance spot welding Layers may be formed. Therefore, the upper limit of the heating temperature is preferably 1000 ° C.
  • the heating temperature here means the highest temperature reached of the steel sheet.
  • the holding time at the maximum plate temperature is not particularly limited. In order to suppress the formation of the oxide layer, a shorter time is preferable, preferably 300 s or less, more preferably 60 s or less, and still more preferably 10 s or less.
  • the heating method examples include heating by an electric furnace or a gas furnace, flame heating, energization heating, high frequency heating, induction heating, and the like.
  • energization heating, high-frequency heating, induction heating, and the like are suitable for setting the average temperature rising rate to 50 ° C./s or more.
  • the hot press molded product can be taken out from the mold and cooled using a liquid or a gas.
  • C 0.23%, Si: 0.25%, Mn: 1.2%, P: 0.01%, S: 0.01%, Al: 0.03%, N: 0.005%, Cr: 0.2%, Ti: A cold-rolled steel sheet containing 0.02%, B: 0.0022%, Sb: 0.008%, the balance being composed of Fe and inevitable impurities, an Ac3 transformation point of 820 ° C, and a sheet thickness of 1.2 mm was used. .
  • alloyed hot-dip Zn plating is about 670 ° C.
  • the melting point of hot-dip Zn plating (GI) and electric pure Zn plating (EG) is about 420 ° C.
  • electric Zn alloy plating (Zn -Ni) has a melting point of about 800 ° C to 880 ° C
  • Zn-Al plating (Zn-Al) has a melting point of about 380 ° C to 400 ° C
  • Zn-Al-Si plating (Zn-Al-Si) has a melting point of about 570
  • the melting point of Al—Si plating (Al—Si) is about 660 ° C., which is about 660 ° C. because it is alloyed with Fe during heating.
  • the above steel sheet was heated to 900 ° C. in the atmosphere for 180 seconds, removed from the furnace without being held at 900 ° C., air-cooled to 700 ° C. in the atmosphere, and immediately shown in FIG.
  • a hot press-molded body was produced by drawing using a press molding method as shown in FIG. The punch width when drawing was 70 mm and the processing height was 30 mm.
  • the presence or absence of mesh-like irregularities on the surface of the plating layer was determined by observing the surface with an SEM. The case where there was unevenness was marked as ⁇ , and the case where there was no unevenness was marked as x.
  • the average roughness of the plating layer was measured at 10 appropriate locations using a surface roughness measuring instrument.
  • the average average roughness was defined as “ ⁇ ” when 3 ⁇ m or more, “ ⁇ ” when 2 ⁇ m or more but less than 3 ⁇ m, and “x” when less than 2 ⁇ m.
  • the thickness of the oxide layer was determined by cross-sectional SEM observation of the plating layer.
  • the reflected electron image was photographed by SEM at 10 times with 1500 magnifications, and the average value of the thickness of the oxide layer formed on the outermost surface was determined from the photographed image.
  • the case where 3 ⁇ m or less is “ ⁇ ” and the case where it exceeds 3 ⁇ m is “ ⁇ ”.
  • the presence or absence of the plating layer was confirmed from the image.
  • the product in which the plating layer remained on 50% or more of the steel sheet surface excluding the oxide layer was indicated as “ ⁇ ”, and the case where it was less than 50% was indicated as “X”.
  • a welding test was performed on the hot press-formed body obtained as described above.
  • an inverter DC resistance spot welder was used, and welding was performed with a chrome-copper DR electrode (electrode tip diameter: 6 mm) at a pressure of 450 kgf and an energization time of 340 msec.
  • the nugget diameter was 4 ⁇ t (t: plate thickness)
  • the appropriate current range defined from the current value (mm) to the occurrence of scattering was determined.
  • An appropriate current range of 1 kA or more was indicated as “good”, and “1.5” or higher was indicated as “ ⁇ ”, indicating an even better weldability.
  • An appropriate current range of less than 1 kA is indicated as “x”.
  • C 0.23%, Si: 0.25%, Mn: 1.2%, P: 0.01%, S: 0.01%, Al: 0.03%, N: 0.005%, Cr: 0.2%, Ti: A cold-rolled steel sheet containing 0.02%, B: 0.0022%, Sb: 0.008%, the balance being composed of Fe and inevitable impurities, an Ac3 transformation point of 820 ° C, and a sheet thickness of 1.2 mm was used. .
  • the surface of this cold-rolled steel sheet is electroplated in a plating bath containing 200 g / L nickel sulfate hexahydrate and 0-50 g / L zinc sulfate heptahydrate at a pH of 3.0 and a temperature of 50 ° C.
  • a plating layer I having an Ni content of 100% (mass%) and an adhesion amount of 0.05 g / m 2 was formed.
  • electroplating was performed in a plating bath containing 200 g / L nickel sulfate hexahydrate and 10 to 100 g / L zinc sulfate heptahydrate at a pH of 1.5 and a temperature of 50 ° C.
  • a plating layer II having a content of 12% and an adhesion amount of 60 g / m 2 was formed.
  • the plated steel sheet was heated under the conditions shown in Table 2 by electric heating or furnace heating, and molded and cooled under the same conditions as in Example 1 to produce a hot press-formed body.
  • Example 2 a welding test was performed on the hot press-formed body obtained as described above under the same conditions as in Example 1.
  • the evaluation criteria were expressed as “ ⁇ ” with an appropriate current range of 1 kA or more as “good” weldability, “ ⁇ ” when 1.5 kA or more was further improved as weldability, and “ ⁇ ” when 2.0 kA or more was further improved as weldability.
  • An appropriate current range of less than 1 kA is indicated as “x”. The same as in the first embodiment.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
  • Coating With Molten Metal (AREA)

Abstract

L'invention fournit un corps moulé à la presse à chaud ainsi que son procédé de fabrication, et une tôle d'acier plaquée pour presse à chaud. Le corps moulé à la presse à chaud ne nécessite pas d'étape de retrait d'oxyde à l'aide d'une grenailleuse, ou similaire, et présente une excellente aptitude au soudage par points par résistance. Le corps moulé à la presse à chaud doté d'un placage est obtenu par moulage à l'aide d'une matrice et simultanément refroidissement, après chauffage de la tôle d'acier plaquée à une température supérieure ou égale à son point de transformation Ac3. À la surface dudit placage, se trouve une couche d'oxyde qui possède des creux et reliefs sous forme de réseau dont la rugosité moyenne Ra est supérieure ou égale à 2µm, et la valeur moyenne de l'épaisseur est inférieure ou égale à 3µm. Enfin, sous cette couche d'oxyde, l'objet de l'invention possède une couche de placage dont le point de fusion est inférieur ou égal à ladite température de chauffage.
PCT/JP2015/003426 2014-07-10 2015-07-07 Corps moulé à la presse à chaud ainsi que procédé de fabrication de celui-ci, et tôle d'acier plaquée pour corps moulé à la presse à chaud Ceased WO2016006232A1 (fr)

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JP2021108370A (ja) * 2019-12-27 2021-07-29 三星電子株式会社Ｓａｍｓｕｎｇ Ｅｌｅｃｔｒｏｎｉｃｓ Ｃｏ．，Ｌｔｄ． 可変抵抗メモリ素子
JP2023027518A (ja) * 2021-08-17 2023-03-02 Ｊｆｅスチール株式会社 Ｚｎ－Ａｌ－Ｍｇ系合金めっき鋼板およびその製造方法
JP2024137398A (ja) * 2023-03-24 2024-10-07 Ｊｆｅスチール株式会社 高強度鋼部材およびその製造方法

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JP2021108370A (ja) * 2019-12-27 2021-07-29 三星電子株式会社Ｓａｍｓｕｎｇ Ｅｌｅｃｔｒｏｎｉｃｓ Ｃｏ．，Ｌｔｄ． 可変抵抗メモリ素子
JP7662262B2 (ja) 2019-12-27 2025-04-15 三星電子株式会社 可変抵抗メモリ素子
US12408566B2 (en) 2019-12-27 2025-09-02 Samsung Electronics Co., Ltd. Variable resistance memory device
JP2023027518A (ja) * 2021-08-17 2023-03-02 Ｊｆｅスチール株式会社 Ｚｎ－Ａｌ－Ｍｇ系合金めっき鋼板およびその製造方法
JP7739833B2 (ja) 2021-08-17 2025-09-17 Ｊｆｅスチール株式会社 Ｚｎ－Ａｌ－Ｍｇ系合金めっき鋼板およびその製造方法
JP2024137398A (ja) * 2023-03-24 2024-10-07 Ｊｆｅスチール株式会社 高強度鋼部材およびその製造方法
JP7794159B2 (ja) 2023-03-24 2026-01-06 Ｊｆｅスチール株式会社 高強度鋼部材およびその製造方法

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