US20080283157A1 - Method of Production of Hot Dipped Hot Rolled Steel Strip - Google Patents

Method of Production of Hot Dipped Hot Rolled Steel Strip Download PDF

Info

Publication number
US20080283157A1
US20080283157A1 US11/887,176 US88717606A US2008283157A1 US 20080283157 A1 US20080283157 A1 US 20080283157A1 US 88717606 A US88717606 A US 88717606A US 2008283157 A1 US2008283157 A1 US 2008283157A1
Authority
US
United States
Prior art keywords
steel strip
hot
rolled steel
hot rolled
reduction
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US11/887,176
Other languages
English (en)
Inventor
Makoto Katsube
Masayuki Miyake
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Nippon Steel Engineering Co Ltd
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Assigned to NIPPON STEEL ENGINEERING CO., LTD., NIPPON STEEL CORPORATION reassignment NIPPON STEEL ENGINEERING CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KATSUBE, MAKOTO, MIYAKE, MASAYUKI
Publication of US20080283157A1 publication Critical patent/US20080283157A1/en
Assigned to NIPPON STEEL & SUMITOMO METAL CORPORATION reassignment NIPPON STEEL & SUMITOMO METAL CORPORATION MERGER (SEE DOCUMENT FOR DETAILS). Assignors: NIPPON STEEL CORPORATION
Abandoned legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • 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
    • 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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • 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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/561—Continuous furnaces for strip or wire with a controlled atmosphere or vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C23C2/003—Apparatus
    • C23C2/0038—Apparatus characterised by the pre-treatment chambers located immediately upstream of the bath or occurring locally before the dipping process
    • 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
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • 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
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
    • C23C2/0222—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating in a reactive atmosphere, e.g. oxidising or reducing atmosphere
    • 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
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
    • C23C2/0224—Two or more thermal pretreatments
    • 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
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/024—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by cleaning or etching
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment

Definitions

  • the present invention relates to a method of production of hot dipped plating hot rolled steel strip produced by the thin slab continuous casting process, hot rolling process and hot dipping plating process.
  • hot rolled steel strip produced by the thin slab continuous casting process is harder to improve in surface quality compared with hot rolled steel strip produced by a conventional continuous casting machine. For this reason, up until recently, the thin slab continuous casting process has not spread in use that widely. Further, there is very little information on hot rolled steel strip produced by the thin slab continuous casting process.
  • hot dip galvanizing this hot rolled steel strip the method used for hot rolled steel strip obtained by a conventional continuous casting machine has been used as it is.
  • non-oxidizing furnace method As the method for hot dip galvanization of hot rolled steel strip, in general a “non-oxidizing furnace method” is used. With this method, hot rolled steel strip is continuously run through a non-oxidizing furnace, reduction furnace (annealing furnace), and cooling furnace to heat it to a high temperature and oxidize and reduce it. By oxidizing hot rolled steel strip in the non-oxidizing furnace, then reducing it in the reduction furnace in this way, an Fe layer can be formed on the hot rolled steel strip surface. The FeO or other oxide film on the hot rolled steel strip surface is resistant to adherence by the hot melt, so removing this from the surface of the hot rolled steel strip has the effect of improving the plating wettability for hot dipping.
  • Such a conventional hot dipping facility is designed mainly for the purpose of processing cold rolled steel sheet, so the temperature elevation rate in the heating zone was about 10° C./s to 20° C./s in range. Further, when using this hot dipping facility to plate hot rolled steel strip, since general steel does not require recrystallization annealing, the maximum temperature at the time of annealing was usually adjusted to 640° C. to 660° C. or so.
  • the “flux method” is also known. With this method, the hot rolled steel strip surface is coated with a flux of zinc chloride, ammonium chloride, etc. to activate the hot rolled steel strip surface and improve the wettability for the hot dipping. However, this method is not generally used for the production of hot dipped steel strip in view of the difficulty of continuous production and plating adhesion.
  • the hot rolled steel strip produced using the thin slab continuous casting process is hot dip galvanized by the method of production of hot dipped steel strip using the above-mentioned “non-oxidizing furnace type plating facility”, nonplating defects are formed on the surface of the hot dip galvanized steel strip. This is believed to be partially due to the addition of Ca specific to the thin slab continuous casting process.
  • a thin slab continuous casting machine has a much narrower casting mold than a conventional continuous casting machine and has an injection nozzle of a special structure as well, so alumina easily clogs the nozzle. Therefore, to prevent this, in a thin slab continuous casting machine, Ca is added to the ladle to lower the melting point of the alumina.
  • a cast 50 mm to 80 mm or so thickness slab is sent directly to the rolling process while held at a high temperature and rolled.
  • This hot rolling mill is a hot rolling mill corresponding to a final rolling machine of a conventional hot rolling process and rolls a slab to a thickness of 1.2 mm to 4 mm or so to produce hot rolled steel strip.
  • a tunnel furnace with a long residence time is used, so a large amount of scale is formed on the slab surface before rolling.
  • the Ca added as explained above and remaining in the thin slab oxidizes in the scale and remains in the form of CaO.
  • the oxide CaO formed by this addition of Ca causes unevenness and pitting in the oxide film on the surface of the hot rolled steel strip when oxidized in the non-oxidizing furnace in the plating process, causes partial degradation of the plating wettability with the hot dip galvanization, and causes plating defects.
  • the hot rolled steel strip produced using the thin slab continuous casting process exhibits a greater amount of smut compared with a conventional continuous casting machine. This is because with the thin slab continuous casting process, the cast steel thin slab is directly sent to the rolling process and rolled while keeping it at a high temperature, so Fe 3 C and C easily remain on the steel strip surface in the separated state. If a lot of these Fe 3 C etc. remain on the surface of the hot rolled steel strip, when oxidized in the non-oxidizing furnace, the C reacts with the oxygen, the formation of an Fe oxide film is partially delayed, and unevenness and pitting are formed on the oxide film. These unevenness and pitting are considered to lower the plating wettability with zinc and cause plating defects.
  • the present invention was made in consideration of the above problems and in particular provides a means for preventing nonplating defects formed on a plate surface when hot dipping hot rolled steel strip produced by the thin slab continuous casting process.
  • a method of production of hot dipped hot rolled steel strip characterized by producing steel strip by casting by a thin slab continuous casting process and hot rolling, said steel strip containing, by mass %, C: 0.03% or more, Si: 0.02% or more, Mn: 0.15% or more, and Ca: 0.001% or more, heating it to a peak maximum steel strip temperature of 550° C. to less than 650° C. by a temperature elevation rate of 25° C./sec or more for 15 sec or more for oxidation, heating it to a peak maximum steel strip temperature of 700° C. to 760° C. so that the time when the steel strip temperature is 570° C. or more is 25 sec to 45 sec for reduction, then hot dipping it.
  • the hot dipping may be made hot dip galvanization.
  • a facility for production of hot dipped hot rolled steel strip which hot dips steel strip produced by casting by the thin slab continuous casting process and by hot rolling
  • which facility for production of hot dipped hot rolled steel strip is characterized by having a furnace used for oxidation and a furnace used for reduction and by a ratio of length between the furnace used for oxidation and the furnace used for reduction along a conveyance direction of the hot rolled steel strip being 0.5 to 0.9.
  • the steel strip can pass through the furnace used for oxidation in a time of 15 sec to 25 sec.
  • the present invention it is possible to prevent nonplating defects formed on the plated surface when hot dipping hot rolled steel strip produced by the thin slab continuous casting process. Further, it is also possible to perform the hot dipping without coil breakage.
  • FIG. 1 is a view of the configuration of a suitable hot dip galvanized hot rolled steel strip production facility according to the present invention.
  • FIG. 2 is a view explaining the temperature changes at a non-oxidizing furnace and annealing furnace of a suitable hot dip galvanized hot rolled steel strip production facility according to the present invention.
  • FIG. 3 gives views before and after oxidation of hot rolled steel strip produced by the thin slab continuous casting process.
  • (a) shows hot rolled steel strip before oxidation
  • (b) shows hot rolled steel strip after oxidation by the present invention
  • (c) shows hot rolled steel strip after oxidation by the prior art.
  • FIG. 4 gives views of the hot rolled steel strip oxidized in a non-oxidizing furnace before and after reduction.
  • (d) shows hot rolled steel strip before reduction
  • (e) shows hot rolled steel strip reduced without excess or shortage
  • (f) shows hot rolled steel strip which is insufficiently reduced
  • (g) shows hot rolled steel strip which is excessively reduced.
  • FIG. 5 is a view of the configuration of a washing apparatus in front of the hot dipping apparatus.
  • hot dip galvanized steel strip SGHC, SGH340, SGH400, SGH440, SGH540, etc. defined by JIS G 3302 are covered.
  • Hot rolled steel strip produced by casting and rolling steel containing, by mass %, C: 0.03% or more, Si: 0.02% or more, Mn: 0.15% or more, and Ca: 0.001% or more by the thin slab continuous casting process is used.
  • Ca is usually added in the steelmaking process by adding CaAl, CaSi, FeCa, or metallic Ca to the molten steel after deoxidation.
  • FIG. 1 is a view of the configuration of a suitable facility for production 1 of hot dip galvanized hot rolled steel strip according to the present invention.
  • This facility for production of hot dip galvanized hot rolled steel strip is comprised of a feeding reel 10 serving as the starting point of the hot dip galvanization process line, a coiling reel 11 serving as the end point, a preheating furnace (not shown) arranged between the reels 10 , 11 , a non-oxidizing furnace 12 , an annealing furnace 15 including a reduction zone 13 and cooling zone 14 , a hot dip galvanization tank 16 , a wiping apparatus 17 , and a cooling furnace 18 .
  • the feeding reel 10 is a reel on which is coiled hot rolled steel strip produced by casting steel containing, by mass %, C: 0.03% or more, Si: 0.02% or more, Mn: 0.15% or more, and Ca: 0.001% or more by the thin slab continuous casting process, then rolling it as is without lowering the temperature.
  • the non-oxidizing furnace 12 is known as a furnace for “slight” oxidation of the hot rolled steel strip fed out from the feeding reel and has a length in the conveyance direction of the steel strip of for example 15 m to 25 m.
  • the processing rate is 120 m/min, so the oxidation time of the hot rolled steel strip in the non-oxidizing furnace 12 is 7 sec to 12 sec.
  • the fuel-air ratio in the non-oxidizing furnace 12 is set to 0.9 to 0.98 or so.
  • the length in the conveyance direction of the non-oxidizing furnace 12 plus the preheating furnace is set to for example 30 m to 50 m.
  • the overall oxidation time (passage time) in the non-oxidizing furnace 12 and preheating furnace becomes 15 sec to 25 sec.
  • the annealing furnace 15 arranged right after the non-oxidizing furnace 12 is comprised of the reduction zone 13 for reducing the oxidized hot rolled steel strip and the cooling zone 14 for cooling the hot rolled steel strip and has a length in the conveyance direction of for example 70 m to 100 m.
  • the processing rate is 120 m/min, so the reduction time of the hot rolled steel strip in the annealing furnace 15 becomes for example 25 sec to 45 sec in the region of 570° C. or more where the reduction is relatively fast.
  • H 2 and N 2 etc. are made the atmosphere in the annealing furnace 15 .
  • the reduction zone in which reduction is mainly performed is comprised of a reduction furnace and soaking furnace or just a reduction furnace. Its length in the conveyance direction is for example set to 50 m to 70 m.
  • the hot dip galvanization tank 16 is a tank for treating hot rolled steel strip for deposition by hot dipping.
  • the wiping apparatus 17 is an apparatus for wiping off excessive molten melt adhered to the hot rolled steel strip by a gas.
  • the cooling furnace 18 is a furnace for then cooling the hot rolled steel strip.
  • FIG. 2 is a view showing the change in temperature of the steel strip surface when the hot rolled steel strip passes through the non-oxidizing furnace 12 , the reduction zone 13 , and the cooling zone 14 of the facility for production 1 of hot dip galvanized hot rolled steel strip.
  • FIG. 2 is a view showing the change in temperature of the steel strip surface when the hot rolled steel strip passes through the non-oxidizing furnace 12 , the reduction zone 13 , and the cooling zone 14 of the facility for production 1 of hot dip galvanized hot rolled steel strip.
  • the temperature point where the hot rolled steel strip enters the non-oxidizing furnace 12 is O
  • the temperature point where it leaves the non-oxidizing furnace 12 is P
  • the temperature point where it enters the reduction furnace of the reduction zone 13 is Q
  • the temperature point where it leaves the reduction furnace of the reduction zone 13 and enters the soaking furnace of the reduction zone 13 is S
  • the temperature point where it leaves the soaking furnace of the reduction zone 13 and enters the cooling zone 14 is T
  • the temperature point where it leaves the cooling zone 14 is V.
  • the hot rolled steel strip produced by the thin slab continuous casting process is fed out from the feeding reel 10 , proceeds on the line, passes through the preheating furnace, and enters the non-oxidizing furnace 12 .
  • the hot rolled steel strip entering the non-oxidizing furnace 12 is heated so that the peak maximum steel strip temperature becomes 550° C. to less than 600° C. at a temperature elevation rate of 25° C./sec or more for a period of 15 sec to 25 sec, whereby the surface of the hot rolled steel strip is oxidized.
  • the “oxidation time” means the time of passage through the preheating zone and non-oxidizing furnace.
  • FIG. 3( a ) shows the hot rolled steel strip before oxidation
  • FIG. 3( b ) shows the hot rolled steel strip after oxidation by the present invention
  • FIG. 3( c ) shows the hot rolled steel strip after oxidation by the prior art.
  • the temperature elevation rate in the section I of FIG. 2 By setting the temperature elevation rate in the section I of FIG. 2 to 25° C./sec or more, which is higher than the above-mentioned conventional temperature elevation rate, the effect of preventing the formation of nonplating defects is obtained. As opposed to this, if setting the temperature elevation rate in the section I at less than 25° C./sec, the oxide CaO and calcium aluminate formed by the addition of Ca and the smut Fe 3 C etc. cause the formation of nonplating defects. The reason why setting the temperature elevation rate at 25° C./sec or more prevents nonplating defects will be explained below.
  • Fe oxide film on the hot rolled steel strip surface is formed by the Fe atoms of the Fe layer moving to the surface layer and reacting with oxygen. Further, when an Fe oxide film is formed, the Si and Mn present in the steel strip are oxidized in the same way as Fe, so SiO 2 and MnO and other secondary oxide films are formed under the Fe oxide film.
  • the formation of an Fe oxide film will be inhibited and the pits 19 shown in FIG. 3( c ) will end up being formed.
  • the temperature elevation rate is set to a high value of 25° C./sec or more and the rate of formation of an Fe oxide film is made large.
  • the concentration of oxygen inside the Fe oxide film of the surface becomes smaller the more to the inside from the surface, so under the Fe 2 O 3 , Fe 3 O 4 (magnetite) is formed at 570° C. or less while FeO (wüstite) is formed at 570° C. or more. These Fe 3 O 4 and FeO grow due to outward diffusion of Fe ions. Therefore, at 570° C. or more, Fe 2 O 3 is formed at the extreme surface of the hot rolled steel strip, Fe 3 O 4 is formed below that, and FeO is formed below that. At less than 570° C., Fe 2 O 3 is formed at the extreme surface and Fe 3 O 4 is formed below that.
  • the properties of the steel strip surface after the end of the temperature elevation process become as follows: As shown in FIG. 3( b ), from the inside, the surface is comprised of Fe (hot rolled steel strip), a secondary oxide film comprised of Si or Mn oxides or Si and Mn composite oxides, and an oxide film comprised of Fe 3 O 4 and FeO or FeO over that. CaO, Fe 3 C are present at the surface. There are pits under the CaO, Fe 3 C, but there is the FeO layer.
  • the peak maximum steel strip temperature in the non-oxidizing furnace is set to 550° C. or more, the effect is obtained that an oxide layer is uniformly formed and the CaO, Fe 3 C, etc. present at the surface part of the oxide film can be easily removed. This effect is not obtained if the peak maximum steel strip temperature is made less than 550° C.
  • the peak maximum steel strip temperature in the non-oxidizing furnace is set to less than 600° C., excessive formation of an oxide film is prevented. If the peak maximum steel strip temperature inside the non-oxidizing furnace is made 600° C. or more, the oxide film will be excessively produced and oxide film will end up remaining in the subsequent reduction.
  • the time for holding the temperature elevation rate at 25° C./sec or more is made 15 sec or more. If less than 15 sec, a sufficient oxide film thickness is not possessed, so as a result, the secondary oxide films comprised of Si or Mn oxides or Si and Mn composite oxides will end up being exposed at the surface without being covered by the FeO film.
  • the oxidized hot rolled steel strip proceeds on the line and enters the reduction zone 13 of the annealing furnace 15 .
  • the strip is heated in the reduction zone 13 to give a peak maximum steel strip temperature of 700° C. to 760° C., then proceeds to the cooling zone 14 where it is cooled.
  • the hot rolled steel strip is reduced in the reduction zone 13 and the cooling zone 14 in the annealing furnace in a state holding the steel strip temperature at 570° C. or more for a period of 25 sec to 45 sec. That is, in FIG. 2 , the time from the temperature point R where the steel strip temperature is 570° C. to the temperature point U is set to 25 sec to 45 sec.
  • the reason for limiting the temperature of the reduction to the region of a temperature of 570° C. or more is as follows: That is, above 570° C., FeO becomes the main Fe oxide and is reduced, while at less than 570° C., Fe 3 O 4 becomes the main Fe oxide and is reduced. FeO, compared with Fe 3 O 4 , is easier to reduce due in part to the high processing temperature. Therefore, the method of reducing FeO is easier to control than reduction of Fe 3 O 4 .
  • the hot rolled steel strip surfaces before and after the above reduction are shown in FIG. 4 .
  • the hot rolled steel strip before reduction is (d)
  • the hot rolled steel strip reduced without excess or shortage is (e)
  • the hot rolled steel strip which is insufficiently reduced is (f)
  • the hot rolled steel strip which is excessively reduced is (g).
  • the CaO and Fe 3 C shown in FIG. 3 are not shown, but these CaO and Fe 3 C are blown away from the steel strip surface by the flow or the reduction atmosphere H 2 , N 2 , and the like when passing through the annealing furnace 13 etc.
  • the secondary oxide films comprised of Si or Mn oxides or Si and Mn composite oxides formed on the Fe (steel strip) are described simply as “SiO 2 , MnO” in FIG. 4 as well.
  • the oxide film in the state of FIG. 3( b ) is suitably reduced and, as shown in FIG. 4( e ), the structure becomes, from the inside, Fe (steel strip), a secondary oxide film comprised of Si or Mn oxides or Si and Mn composite oxides, and a film of Fe above that. Pits where CaO and Fe 3 C had been present remain on the surface, but there is an Fe layer at the bottom.
  • the surface of the hot rolled steel strip shown in FIG. 4( d ) is reduced without excess or shortage in the annealing furnace 15 .
  • the Fe oxide film formed by the non-oxide film is reduced and becomes a completely Fe layer. Further, this Fe layer completely covers the SiO 2 , MnO, and other secondary oxide films formed by the oxidation and reduction as well. The SiO 2 , MnO, and other secondary oxide films degrading the plating wettability with the hot dip galvanization are completely covered, so the plating wettability becomes extremely good, and nonplating defects do not occur.
  • the reduction in the annealing furnace 15 becomes excessive.
  • the Fe oxide film is sufficiently reduced and an Fe layer is formed.
  • Si and Mn have a stronger oxidizing power than Fe, so even when the Fe oxide film is reduced by the annealing furnace 15 , secondary oxide layers of SiO 2 and MnO excessively grow and end up appearing at the steel strip surface. As explained above, SiO 2 and MnO degrade the plating wettability of hot rolled steel strip, so nonplating defects end up being formed.
  • the reduced hot rolled steel strip proceeds on the line from the annealing furnace 15 to a hot dip galvanization tank 16 heated to a predetermined temperature where it is dipped and hot dip galvanized.
  • the hot dip galvanized hot rolled steel strip proceeds on the line and the deposition of the hot dip galvanization on the hot rolled steel strip is adjusted to a predetermined amount by a wiping apparatus 17 .
  • the hot rolled steel strip proceeds on the line and is cooled in the cooling furnace 18 .
  • the hot rolled steel strip entering the non-oxidizing furnace 12 is heated to give a peak maximum steel strip temperature of 550° C. to less than 600° C. at a temperature elevation rate of 25° C./sec or more over a period of 15 sec to 25 sec for oxidation.
  • a peak maximum steel strip temperature of 550° C. to less than 600° C. at a temperature elevation rate of 25° C./sec or more over a period of 15 sec to 25 sec for oxidation.
  • the oxidized hot rolled steel strip is heated to give a peak maximum steel strip temperature of 700° C. to 760° C. while holding the steel strip temperature at 570° C. or more for 25 sec to 45 sec to reduce it, whereby the Fe oxide film on the hot rolled steel strip surface is reduced without excess or shortage. Further, no secondary oxide layers of SiO 2 and MnO appear on the surface either. Therefore, the formation of nonplating defects can be prevented.
  • the length in the conveyance direction of the furnace used for oxidation was set to 30 m to 50 m, while the length in the conveyance direction of the furnace used for reduction (reduction zone 13 ) was set to 50 m to 70 m. From experiments, it reveals that if the ratio of lengths along the conveyance direction of the furnace used for oxidation and the furnace used for reduction is 0.5 to 0.9, a good plating state can be obtained. In the present embodiment, by setting the ratio of lengths along the conveyance direction of the furnace used for oxidation and the furnace used for reduction to be 0.5 to 0.9, the formation of nonplating defects can be prevented. Further, the furnace used for oxidation and the furnace used for reduction are set to suitable lengths without excess or shortage, so the investment in capital cost are optimized.
  • the hot rolled steel strip was fed out from a feeding reel, but it is also possible to directly connect it to a line performing thin slab continuous casting.
  • the hot rolled steel strip was fed out from a feeding reel to the non-oxidizing furnace, but it may also be treated by pickling, surface scrubbing, etc. before being fed out to the non-oxidizing furnace.
  • the hot rolled steel strip was fed out from a feeding reel to the inside of the non-oxidizing furnace, but it is also possible to provide an apparatus for pickling, surface scrubbing, and other processing before oxidation.
  • an annealing furnace including a reduction zone and cooling zone was used, but it is also possible to use separate furnaces such as a reduction furnace and a cooling furnace.
  • hot dip galvanization was used, but aluminum, lead, tin, etc. may also be used other than zinc.
  • the present invention is particularly effective in hot rolled steel strip.
  • the reason is believed to be that the surface of hot rolled steel strip has coarser grain boundaries, larger surface areas, easier oxidation and reduction, and larger growth rate of the oxide layer.
  • the conventional formulas for estimating the amount of oxidation and amount of reduction of cold rolled steel sheet are applied to hot rolled steel strip giving a good plating state under the oxidation and reduction conditions of the present invention so as to calculate the amount of oxidation and amount of reduction of hot rolled steel strip.
  • the formula for estimating the amount of oxidation of cold rolled steel sheet estimates the amount of oxidation from the two variables of time stayed in the preheating furnace and non-oxidizing furnace and the peak temperature of the cold rolled steel sheet.
  • the formula for estimating the amount of reduction of cold rolled steel sheet estimates the amount of reduction from the two variables of time stayed in the reduction furnace and the peak temperature of the cold rolled steel sheet.
  • the amount of reduction in the case of a temperature of the reduction furnace of 570° C. or more and the amount of reduction in the case of less than 570° C. are separately calculated and the sum of the two is estimated as the amount of reduction.
  • the specific forms of the formulas for estimation of the amount of oxidation and amount of reduction are not shown, but can be derived from experiments.
  • Hot rolled steel strips obtained by hot rolling cast slabs obtained by a thin slab casting machine were oxidized and reduced under suitable oxidation and reduction conditions defined by the present invention.
  • the values of the amounts of oxidation and amounts of reduction were found by the above formulas for estimating the amount of oxidation and amount of reduction.
  • the amounts of oxidation were 0.12 to 0.2 mg/m 2 or so, and the amounts of reduction were 0.2 to 0.35 mg/m 2 or so. These values are smaller compared with the amounts of oxidation of 0.1 to 0.8 mg/m 2 and amounts of reduction of 0.45 to 1 mg/m 2 of cold rolled steel sheet obtained by the same formulas.
  • the oxidation rate and the reduction rate are faster than the case of cold rolled steel sheet, so it can be estimated that the calculated values of the suitable amount of oxidation and amount of reduction when hot dip galvanizing hot rolled steel strip would give smaller values than the values in the case of cold rolled steel sheet.
  • the oxidation time and reduction time can be shortened. Further, the length of the furnaces for the oxidation and reduction can be shortened and therefore the hot dip galvanization facility can be reduced in size.
  • an alkali washing system comprised of an alkali spray tank 20 , alkali scrubber tank 21 , warm water rinse tank 22 , and hot air drier 23 and not using electrolytic washing and an alkali scrubber using nylon brushes 24 are arranged.
  • the reason why the generally used electrolytic washing is not used is that when using a thin slab continuous casting machine and a hot rolling mill connected with it to produce hot rolled steel strip, the thin slab is hot rolled, then the hot rolled steel strip surface is pickled and coated with a rust preventative.
  • the time from the pickling to the hot dipping is 2 days or less or so, therefore the amount of the rust preventative coated may be made smaller from the usual circumstances.
  • the steel strip surface has a small amount of rust preventative and rust preventative and Fe 3 C etc. present on it, so the alkali washing system not using electrolytic washing is used to wash off the rust preventative, Fe 3 C, etc. adhering to the surface, then an alkali scrubber using nylon brushes is used to remove the rust preventative, Fe 3 C, etc.
  • This washing removes the rust preventative usually burned off in a heating furnace.
  • the oxygen in the atmosphere is used to stabilize the oxidation of the hot rolled steel strip surface. Therefore, the amount of formation of oxide film is stable, so this is a good condition for preventing nonplating defects.
  • the suitable ratio of the amount of oxidation and amount of reduction when dealing with hot rolled steel strip obtained by hot rolling a cast slab obtained by a thin slab casting machine was found by experiments to be 0.4 to 0.55 or so. As opposed to this, in the case of conventional cold rolled steel sheet, it was 0.2 to 1.2 or so, i.e., the values fluctuated.
  • the usual processing rate in the current art is 90 mpm to 180 mpm, so it is possible to apply the present invention to newly establish or modify hot dipping facilities having this range of rates.
  • the upper limit of the processing rate of a hot dipping facility is, in the current art, 180 mpm or so. However, even if a hot dipping facility with an even higher processing rate is developed, the present technology can be applied. Further, the lower limit of the processing rate may be any rate so long as the conditions of the present invention can be realized.
  • Some hot dip galvanization facilities are limited in terms of economic ton/hr of the furnaces. In such a case, if the strip becomes thicker, the processing rate is reduced, so the time for passage through the oxidation furnace becomes longer and as a result the average temperature elevation rate becomes smaller. In this case, the facility may also be operated so that part of the temperature elevation process satisfies the temperature elevation rate of the present invention.
  • the amount of coating of the hot dip galvanization was in the range of 80 to 120 g/m 2 (one side).
  • the Data Nos. 1 to 4 are examples satisfying all of the conditions defined in the present invention.
  • the surfaces of the produced hot dip galvanized hot rolled steel strips were extremely good in terms of plating state.
  • the Data No. 3 and 4 shown in Table 4 had lengths of preheating furnaces fixed at 17 m and lengths of non-oxidizing furnaces fixed at 21 m, had different cooling conditions, and had lengths of reduction zones adjusted to become pseudo 41 m and 78 m.
  • the reduction time is the value calculated from a processing rate of 120 m/min.
  • Data No. 1 and 2 are examples where the ratio of the total length of the preheating furnace and non-oxidizing furnace and the length of the reduction zone satisfies the condition of being in the range of 0.5 to 0.9 defined in the present invention.
  • the surfaces of the produced hot dip galvanized hot rolled steel strips were extremely good in terms of plating state.
  • the Data No. 3 and 4 shown in Table 4 are comparative examples where the ratio of the total length of the preheating furnace and non-oxidizing furnace and the length of the reduction zone is outside of the range of 0.5 to 0.9 defined in the present invention.
  • the surfaces of the produced hot dip galvanized hot rolled steel strips had nonplating defects and other plating defects.
  • the present invention is worked in the range of processing rate shown in the examples.
  • the upper limit of the processing rate is, with current technology, 180 mpm or so.
  • the present technology can be applied.
  • the lower limit of the processing rate may be any rate so long as the conditions of the present invention can be realized.
  • the usual processing rate in current technology is 90 mpm to 180 mpm, so some hot dip galvanization facilities are limited in terms of economic ton/hr of the furnaces. In such a case, if the hot rolled steal strip becomes thicker, the processing rate is reduced, so the time for passage through the oxidation furnace becomes longer and as a result the temperature elevation rate becomes smaller. In this case, the facility may also be operated so that part of the temperature elevation process satisfies the temperature elevation rate of the present invention.
  • the present invention is effective for preventing nonplating defects from occurring on plated surfaces when hot dip galvanizing hot rolled steel strip produced by the thin slab continuous casting process.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Coating With Molten Metal (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Steel (AREA)
US11/887,176 2005-03-30 2006-03-27 Method of Production of Hot Dipped Hot Rolled Steel Strip Abandoned US20080283157A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2005-097390 2005-03-30
JP2005097390 2005-03-30
PCT/JP2006/306987 WO2006106999A1 (ja) 2005-03-30 2006-03-27 溶融めっき熱延鋼板の製造方法

Publications (1)

Publication Number Publication Date
US20080283157A1 true US20080283157A1 (en) 2008-11-20

Family

ID=37073549

Family Applications (1)

Application Number Title Priority Date Filing Date
US11/887,176 Abandoned US20080283157A1 (en) 2005-03-30 2006-03-27 Method of Production of Hot Dipped Hot Rolled Steel Strip

Country Status (5)

Country Link
US (1) US20080283157A1 (zh)
JP (1) JP4619404B2 (zh)
CN (2) CN101994073B (zh)
BR (1) BRPI0607715B1 (zh)
WO (1) WO2006106999A1 (zh)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100193081A1 (en) * 2007-06-29 2010-08-05 Arcelormittal France Process for manufacturing a galvannealed steel sheet by dff regulation
US20110076477A1 (en) * 2007-12-20 2011-03-31 Voestalpine Stahl Gmbh Method for producing coated and hardened components of steel and coated and hardened steel strip therefor
EP3138931A1 (en) * 2014-07-02 2017-03-08 JFE Steel Corporation Method for manufacturing high-strength hot-dip galvanized steel sheet

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103978035B (zh) * 2014-04-28 2016-09-07 雷光瑞 热轧钢的加工方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3730758A (en) * 1970-10-29 1973-05-01 Bethlehem Steel Corp Method of protecting ferrous strip in hot-dip processes
US4615749A (en) * 1984-02-18 1986-10-07 Kawasaki Steel Corporation Cold rolled dual-phase structure steel sheet having an excellent deep drawability and a method of manufacturing the same
US5137586A (en) * 1991-01-02 1992-08-11 Klink James H Method for continuous annealing of metal strips
US20030047257A1 (en) * 2000-05-31 2003-03-13 Chikara Kami Cold-rolled steel sheet having excellent strain aging hardening properties and method for producing the same
US6537398B1 (en) * 1998-12-18 2003-03-25 Avestapolarit Ab (Publ) Method for manufacturing of strips of stainless steel and integrated rolling mill line

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3520155B2 (ja) * 1996-05-27 2004-04-19 新日本製鐵株式会社 高歪速度時の変形抵抗に優れた自動車用高張力合金化溶融亜鉛めっき熱延鋼板およびその製造方法
JP3882679B2 (ja) * 2002-05-23 2007-02-21 Ｊｆｅスチール株式会社 めっき外観の良好な深絞り性に優れた複合組織型高張力溶融亜鉛めっき冷延鋼板の製造方法
JP4119804B2 (ja) * 2003-08-19 2008-07-16 新日本製鐵株式会社 密着性の優れた高強度合金化溶融亜鉛めっき鋼板及びその製造方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3730758A (en) * 1970-10-29 1973-05-01 Bethlehem Steel Corp Method of protecting ferrous strip in hot-dip processes
US4615749A (en) * 1984-02-18 1986-10-07 Kawasaki Steel Corporation Cold rolled dual-phase structure steel sheet having an excellent deep drawability and a method of manufacturing the same
US5137586A (en) * 1991-01-02 1992-08-11 Klink James H Method for continuous annealing of metal strips
US6537398B1 (en) * 1998-12-18 2003-03-25 Avestapolarit Ab (Publ) Method for manufacturing of strips of stainless steel and integrated rolling mill line
US20030047257A1 (en) * 2000-05-31 2003-03-13 Chikara Kami Cold-rolled steel sheet having excellent strain aging hardening properties and method for producing the same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100193081A1 (en) * 2007-06-29 2010-08-05 Arcelormittal France Process for manufacturing a galvannealed steel sheet by dff regulation
US20110076477A1 (en) * 2007-12-20 2011-03-31 Voestalpine Stahl Gmbh Method for producing coated and hardened components of steel and coated and hardened steel strip therefor
US9090951B2 (en) 2007-12-20 2015-07-28 Voestalpine Stahl Gmbh Method for producing coated and hardened components of steel and coated and hardened steel strip therefor
EP3138931A1 (en) * 2014-07-02 2017-03-08 JFE Steel Corporation Method for manufacturing high-strength hot-dip galvanized steel sheet
EP3138931A4 (en) * 2014-07-02 2017-05-03 JFE Steel Corporation Method for manufacturing high-strength hot-dip galvanized steel sheet

Also Published As

Publication number Publication date
CN101155935B (zh) 2011-08-03
CN101994073B (zh) 2012-06-27
JP4619404B2 (ja) 2011-01-26
JPWO2006106999A1 (ja) 2008-09-25
WO2006106999A1 (ja) 2006-10-12
BRPI0607715B1 (pt) 2014-12-16
CN101155935A (zh) 2008-04-02
CN101994073A (zh) 2011-03-30
BRPI0607715A2 (pt) 2009-10-06

Similar Documents

Publication Publication Date Title
EA010615B1 (ru) Способ и устройство для удаления окалины с металлической полосы
JP2010525174A (ja) Ａｈｓｓまたはｕｈｓｓストリップ材料の溶融亜鉛めっき方法、及びそのような材料
US20080283157A1 (en) Method of Production of Hot Dipped Hot Rolled Steel Strip
KR100985349B1 (ko) 연속용융도금설비 및 방법
JP3176843B2 (ja) 溶融亜鉛めっき鋼板の製造方法および製造設備
JP2964911B2 (ja) Ｐ添加高張力鋼材の合金化溶融亜鉛めっき方法
JPS6056418B2 (ja) 溶融亜鉛メツキ鋼板の製造法
JPH07216524A (ja) 高張力熱延鋼板の溶融めっき方法
JP5386772B2 (ja) 合金化溶融亜鉛メッキ鋼帯の製造方法
JP2007291445A (ja) 濡れ性、ふくれ性に優れた高張力溶融亜鉛めっき熱延鋼板の製造方法
JPH10330900A (ja) 熱延鋼板の溶融めっき方法
KR101748975B1 (ko) 강 시트의 열 처리 방법 및 이를 실시하기 위한 디바이스
KR100985370B1 (ko) 열연강대의 연속용융도금설비 및 도금방법
JP2001262303A (ja) 溶融めっき性に優れた溶融亜鉛めっき鋼板および合金化溶融亜鉛めっき鋼板の製造方法
KR940000872B1 (ko) 가공성 및 도금밀착성이 우수한 용융아연 열연강판의 제조방법
JP3219010B2 (ja) 熱延鋼板の溶融めっき設備および溶融めっき鋼板の製造方法
KR20000045512A (ko) 도금밀착성이 우수한 고강도 열연용융아연 도금강판의 제조방법
JPH04247829A (ja) 表面性状と成形性に優れた熱延鋼板の製造方法
RU2403315C2 (ru) Способ покрытия стального плоского проката из высокопрочной стали
JP2000204462A (ja) 溶融亜鉛めっき鋼板及び合金化溶融亜鉛めっき鋼板の製造方法
JPH03281764A (ja) 表面外観の優れた深絞り用合金化溶融亜鉛めっき鋼板の製造方法
JPH10140311A (ja) 熱延鋼板の溶融めっき方法および溶融めっき設備
JPH1046307A (ja) 溶融めっき鋼板の製造方法
JPH04304357A (ja) 溶融Ｚｎ−Ａｌ系合金めっき熱延鋼帯の製造方法
JPH05279829A (ja) 高張力合金化溶融亜鉛めっき鋼板の製造方法

Legal Events

Date Code Title Description
AS Assignment

Owner name: NIPPON STEEL CORPORATION, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KATSUBE, MAKOTO;MIYAKE, MASAYUKI;REEL/FRAME:020187/0391

Effective date: 20071019

Owner name: NIPPON STEEL ENGINEERING CO., LTD., JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KATSUBE, MAKOTO;MIYAKE, MASAYUKI;REEL/FRAME:020187/0391

Effective date: 20071019

AS Assignment

Owner name: NIPPON STEEL & SUMITOMO METAL CORPORATION, JAPAN

Free format text: MERGER;ASSIGNOR:NIPPON STEEL CORPORATION;REEL/FRAME:029866/0762

Effective date: 20121001

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION